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The Sun · Sunlight Matters

• 0:00
  Bob: Increasingly, I realized in over nearly 10 years of doing this, most of modern science is so siloed, so narrow, uh that people rarely get the chance to look at the big picture.
• 0:11
  Bob: And so I kind of became a big picture person.
• 0:14
  Bob: And I realized that the result of this siloing in these subjects, especially biology, meant that people were working on fantastic things, you know, the movement of electrons in mitochondria from one place to another in intricate detail, wonderful stuff, but nobody saw the big picture.
• 0:33
  Bob: And it turns out the activation energy, which has been determined by biologists over all life forms from bacteria to the blue whale, is around 0.7 electron volts.
• 0:43
  Bob: Almost exactly the same as the peak photon flux coming from the sun.
• 0:48
  Bob: I thought, that's not an accident.
• 0:49
  Bob: The structures that you have to maintain your homeostasis are tuned to an energy source which allows can allow you to overcome these barriers, but in a controlled manner.
• 1:00
  Bob: Well, there's a word for this.
• 1:01
  Bob: It's called hometis.
• 1:02
  Bob: You have to stress yourself in order to remain healthy.
• 1:06
  Bob: You give yourself small doses of stress, like the toxic chemicals and so on.
• 1:11
  Bob: You need to get your body to react to um difficulty.
• 1:18
  Bob: It forces you to build the complexity.
• 1:23
  Speaker: Welcome to Sunlight Matters, the podcast that reconnects us with the sun.
• 1:28
  Speaker: Join us as we explore the power and influence of our star, the force at the heart of everything.
• 1:33
  Speaker: Each episode, we speak with leading experts to uncover the ways sunlight shapes our world.
• 1:41
  Dave: Welcome to today's episode of Sunlight Matters.
• 1:44
  Dave: Joining Gail and I is uh an incredible person, Bob Fosbury.
• 1:50
  Dave: So welcome to the show, Bob.
• 1:52
  Dave: I I wonder, could you do a brief introduction to yourself?
• 1:57
  Dave: Uh and then, you know, let's get on with talking about some of the big themes that we want to talk to you about.
• 2:04
  Bob: Okay, right.
• 2:05
  Bob: Um I'm interested in interdisciplinarity.
• 2:08
  Bob: I mean, I'm an astrophysicist.
• 2:10
  Bob: I worked for 50 years on an astronomical career.
• 2:13
  Bob: I'm still doing it, actually.
• 2:14
  Bob: I'm still doing it in the background.
• 2:16
  Bob: But um, so I I grew up in British astronomy initially through the Royal Greenwich Observatory, where I did my D Phil at Sussex.
• 2:25
  Bob: Uh, then I went to Australia to work on the Anglo-Australian Telescope, and then I worked a bit on the La Palma telescopes.
• 2:33
  Bob: Uh and then I uh received a phone call inviting me to join the European Space Agency to work on the Hubble Space Telescope program, uh, which I started doing in 1985, uh, five years before launch.
• 2:48
  Bob: And I worked on that program for I think 26 years.
• 2:51
  Bob: Wow.
• 2:52
  Bob: Both as an astrophysicist working with data and so on.
• 2:55
  Bob: And uh but I was hosted by the European Southern Observatory in Munich, in Germany, and uh so I lived there for a very long time.
• 3:03
  Bob: And um uh I had a very, very exciting astronomical career using the major telescopes around the world, Hawaii, uh, Chile, and so on.
• 3:16
  Bob: I was involved with many projects.
• 3:18
  Bob: I was chairman of the ESO faculty, which was the largest faculty of uh um astronomers, I think, in the world at the time, 80 PhD astronomers and so on.
• 3:28
  Bob: So I I had a I had a sort of mixed academic and operational role in helping ESA with the uh uh their their collaboration with NASA on Hubble, and also a little bit on the development of the James Webb Space Telescope.
• 3:43
  Bob: I was involved uh in a relatively small way with the development of the early development of the instrumentation for the James Webb Space Telescope.
• 3:52
  Bob: When I retired from ESA in the end of 2010, I didn't really want to follow many of my colleagues who, when they retired, just continued doing astronomy, uh, just continued doing exactly what they were doing before, but not being paid for it.
• 4:07
  Bob: And I uh I accidentally came in contact with Glenn Jeffrey, I mean, completely accidentally, when I was in Durham on a fellowship.
• 4:16
  Bob: And uh we worked on reindeer vision, which turned out to be very interesting and all to do with photonics, um, photonic crystals in in life and so on.
• 4:26
  Bob: And um, you know, his main project at the time was working on the effect of infrared light on vision and uh slowing macular degeneration by um uh by making sure that the eye was bathed in infrared light occasionally.
• 4:42
  Bob: And uh, well, I won't go into the details of that, but basically I got very interested in this whole question of the interaction of light with biology and uh you know realized that there's not very much known.
• 4:56
  Bob: And uh increasingly I realized in over over nearly 10 years of doing this, most of modern science is so siloed, uh so narrow, uh that people rarely get the chance to look at the big picture.
• 5:14
  Bob: And so I kind of became a big picture person, and I was in a great position to do that, because of course I spent my whole career doing astronomy.
• 5:23
  Bob: I I published papers in the Journal of Solar Physics, and also published papers on the edge of the universe and the properties of black holes and so on.
• 5:32
  Bob: So I had this enormous perspective just by virtue of where I was and what I was doing.
• 5:38
  Bob: And uh, you know, I'm not trained in chemistry or biology to any significant level, but you know, I was trained in physics.
• 5:47
  Bob: And I realized that the result of this siloing in these subjects, especially biology, meant that people were working on fantastic things, you know, the movement of electrons in mitochondria from one place to another in intricate detail, wonderful stuff.
• 6:06
  Bob: But nobody saw the big picture.
• 6:08
  Bob: And then when I came across this, I mean I found in the literature, I found the early literature on this topic of uh uh uh scaling factors in in biology, and I looked at the original papers and I thought, golly, you know, this is this is really important stuff.
• 6:26
  Bob: And of course, Jeffrey West, who wrote this book, was a particle physicist.
• 6:30
  Bob: He was trained in high-energy physics.
• 6:33
  Bob: He was involved with the development of the detectors, well, what was going to become the superconducting supercollider.
• 6:41
  Bob: So he was working at Los Alamos, he was head of one of the detector uh teams on for the hadron for the collider.
• 6:48
  Bob: And uh when he you know kind of lost his job because they cancelled the collider, um, he he moved into biology because he wanted to understand death.
• 6:59
  Bob: What what's what what determines your lifespan?
• 7:03
  Bob: And this is how he got into the scaling law.
• 7:06
  Bob: And the scaling law that came out was absolutely he didn't discover the scaling law.
• 7:10
  Bob: This is actually discovered by Kleiber in in in the 30s.
• 7:14
  Bob: And um but but they figured it out.
• 7:17
  Bob: He and James Brown and a student at Enquist, they sorted all this out in the in the late 90s and early 2000s, and uh it was revolutionary for biology, but it seems to me that most biologists didn't notice this.
• 7:30
  Bob: And it's incredibly important for ecology and uh you know how animals work in different environments and so on.
• 7:36
  Bob: So, you know, the the what I've been doing over the last year or so is trying to understand this interface between the biological, the mathematical biology, you know, the scaling laws between different properties of life, and what that implied for the energy flow into biology.
• 7:59
  Bob: So what we're doing is bioenergetics.
• 8:02
  Bob: You know, biology has been dominated by genetics for the last 50 years.
• 8:08
  Bob: And uh, you know, there's some obviously some people working on bioenergetics.
• 8:14
  Bob: Nick Lane is one of them, very well known.
• 8:17
  Bob: Um, but uh, you know, the energetics of life is absolutely crucial.
• 8:23
  Bob: And it just turns out, and this has only happened to me over the last few months, I must say, the last few months have been just an amazing intellectual storm for me to suddenly realize that all these big pieces of jigsaw that we were jostling around trying to fit together, suddenly they all came together.
• 8:42
  Bob: And it was an extraordinary experience.
• 8:44
  Bob: And I I did one plot just a few weeks ago when I was on holiday, and I I plotted two points on a diagram, and I thought, gosh, you know, that's that's what we're talking about.
• 8:56
  Bob: The whole process of metabolism is to do with sunlight.
• 9:01
  Bob: And of course, we know sunlight is crucial for photosynthesis.
• 9:04
  Bob: We've known this for a long time.
• 9:06
  Bob: You know, it's only recently it's really been understood at sort of quantum mechanical level, uh, and not completely understood yet, I'm sure, but um photosynthesis is is crucial because it basically drives life on Earth.
• 9:21
  Bob: I mean, not all life, completely all life, but pretty much everything we know about is driven by photosynthesis.
• 9:28
  Bob: And then we gradually realized that there was a parallel process going on to photosynthesis, which was its inverse.
• 9:34
  Bob: You produce the food, but then how do you metabolize the food to drive your cells?
• 9:40
  Bob: How do you create ATP, this currency that that cells use to energize themselves?
• 9:47
  Bob: How do you how do you generate ATP?
• 9:50
  Bob: And the reason we made these discoveries, and I think this is very important, is that what we did in lighting over the last 50 years, all life on Earth has evolved under thermal light sources, i.e., things that radiate because they're hot.
• 10:10
  Bob: Sunlight is a you know perfect example, and sunlight is the obvious.
• 10:14
  Bob: But you know, you think of all the other ways life has interacted with light.
• 10:18
  Bob: Fires, you know, in the early days of human civilization, candles, oil lamps, they're all thermal sources of radiation.
• 10:27
  Bob: And that thermal sources of radiation have a very broad spectrum.
• 10:31
  Bob: And we, at this time, we were getting fussed about using energy, and so we were trying to design very clever light bulbs that only produce visible light.
• 10:41
  Bob: And so we could save energy.
• 10:43
  Bob: And the fluorescent tube, you know, obviously was a and these compact fluorescent tubes and so on, they were all doing this.
• 10:49
  Bob: There was very little broad spectrum light.
• 10:52
  Bob: Most of the light comes out in the visible.
• 10:54
  Bob: And then this wonderful idea of the blue LED, which would excite phosphors to make white LED lights, got the Nobel Prize, for goodness sake.
• 11:03
  Bob: Fantastic idea.
• 11:04
  Bob: Now we can light the world.
• 11:06
  Bob: And so for the last decade or so, we've been lighting the world with this wonderfully efficient LED light, which is killing us.
• 11:14
  Bob: And I'm not being, you know, I'm not exaggerating about this.
• 11:18
  Bob: White light on its own, white LED light, we now have the evidence.
• 11:23
  Bob: Glenn and Glenn and people are working on a paper about this.
• 11:27
  Bob: It's not only um not good for us, but it actually damages.
• 11:33
  Bob: Uh uh, it it damages mitochondrial function.
• 11:37
  Bob: And so, you know, if we live in the built environment now, which most people do for most of the time, they're sitting in a building that has white LED lights.
• 11:47
  Bob: There's one of them here on my desk.
• 11:49
  Bob: Actually, this light is a is a 60-watt tungsten filament lamp dimmed with a dimmer.
• 11:54
  Bob: And that keeps me alive.
• 11:56
  Bob: And this one allows this this one allows me to see.
• 12:02
  Dave: So they dual function, okay?
• 12:05
  Dave: But I mean, it it's uh it's amazing.
• 12:08
  Dave: It's amazing.
• 12:10
  Bob: Um But it's so obvious in retrospect.
• 12:12
  Bob: It's so obvious in retrospect.
• 12:14
  Bob: And what they're doing in buildings now, and they have to do this, if you build a skyscraper, you have to reject the infrared, otherwise your skyscraper would fry everybody because of you know thermal imbalance and so on.
• 12:25
  Bob: So the glass manufacturers are proudly making glass now that only admits visible light into buildings.
• 12:32
  Bob: And the combination of that and the white LEDs, mean if if you live in if you're a if you're somebody in Saudi Arabia living in a skyscraper and you've got plenty of money, you never go into sunlight.
• 12:46
  Bob: You go from your skyscraper to your air-conditioned car with infrared rejecting windows and it and LED lights.
• 12:55
  Bob: So you're living entirely under LED lights, which is what the astronauts in the space station do.
• 13:01
  Bob: And I think, and we've written, the Guy Foundation has written a report to the space agencies about this.
• 13:07
  Bob: The reason astronauts come back fit sick from the space station is at least partly, and I think predominantly, because they're living under white LED lights and they never get infrared light.
• 13:21
  Dave: So that's if Elon wants to go to Mars, he definitely needs a few incandescent lights in the uh in the spaceship.
• 13:30
  Dave: Bob he can he can figure that out.
• 13:32
  Dave: Yeah.
• 13:32
  Dave: Well, absolutely.
• 13:34
  Dave: But Bob, I I mean, utterly amazing.
• 13:37
  Dave: I think the fact that you've gone from astrophysics into biology is and you've kind of done the silo busting along the way, and you're starting to figure all of this stuff out, I think is is incredible.
• 13:52
  Dave: And I I think that was a it was a tremendous introduction.
• 13:57
  Dave: Um, and it kind of sets the scene.
• 14:00
  Dave: But I think one of the things I was keen to do was for you to replay a bit of the presentation that you did the other day, which was about the origins of the universe.
• 14:09
  Dave: So taking you back to Hubble and the James Webb experience that you had, where you peered back in time.
• 14:16
  Dave: And I think the reason it's important is because it sets the scene for life today.
• 14:25
  Dave: Like without what happened in the Big Bang, and from what you said, without what happened in the Big Bang and the subsequent steps that happened along the way, we we couldn't be where we are doing what we're doing.
• 14:40
  Dave: And so I was keen for you to do that.
• 14:42
  Dave: And then I was also keen to spend a bit of time demystifying the sun, because the sun is like for us, is is is the the kind of main the main giver of life in terms of in in terms of many things.
• 14:58
  Dave: It but it I guess a lot of people don't really understand what's going on in the sun, how big it is, so some of the fundamentals as well.
• 15:06
  Georg: So it's our boss, so it's really crucially uh yeah.
• 15:10
  Dave: So if we could start by by going through that sort of the a brief history of time, that would be brilliant.
• 15:17
  Bob: Yeah, okay.
• 15:18
  Bob: Well, uh I in fact I I I wrote an essay on um the life universe and everything seen in colour uh for the Bath Royal Literary and Scientific Institution.
• 15:27
  Bob: And I gave that lecture in 2017, and it's on Flickr, the website Flickr.
• 15:33
  Bob: And actually it's my it's my most popular Flickr post.
• 15:36
  Bob: It's a photographic website, but I've got I've got about 10 pages of text in there.
• 15:42
  Bob: And it's being viewed, I think, 25,000 times now, uh, which is for Flickr, is quite a large number.
• 15:48
  Bob: So I can I can actually I can send you that essay, and that covers my view of that, you know, some years ago now.
• 15:55
  Bob: So it doesn't include any of the more recent stuff, but it certainly includes the idea of the big picture of what's going on in the universe.
• 16:03
  Bob: But what I did in the talk, I started off with the idea of um showing what the history of the universe in in the way that I showed it on a sort of logarithmic time scale, uh, right from the very beginning.
• 16:18
  Bob: And the first event that we can see clearly now is the cosmic microwave background, which happened about 380,000 years after the Big Bang.
• 16:31
  Bob: This is known quite precisely from the studies of the background itself.
• 16:36
  Bob: And uh that was the moment when the the the Big Bang fireball, if you like to call it that, became transparent, and huge numbers of photons were uh set uh uh was set free to flow through outer space.
• 16:52
  Bob: And they're still the dominant form of the dominant source of photons in the universe at the moment by a large factor.
• 16:59
  Bob: It's the cosmic microwave background.
• 17:01
  Bob: Now the thing is when that started, when the cosm when that when those photons were emitted, they were emitted at a much higher temperature than they are now, because the universe has expanded by a factor of uh uh a thousand or more than a thousand since then.
• 17:17
  Bob: So the photons emitted were a perfect black body at 3,000 Kelvins, which is the temperature of a hot tungsten filament lamp, incidentally, and that's a coincidence, which I like to I like to use.
• 17:33
  Bob: So, you know, we we're we're struggling to get back to to the first light in the universe in our rooms, and failing at the moment.
• 17:42
  Bob: Except I'm I'm not failing, I've got one here.
• 17:45
  Bob: But this was the first light that was emitted into the universe.
• 17:48
  Bob: And the reason I included that in the talk was because we see that we see that light all around us on the sky.
• 17:57
  Bob: It's it's all around the sky.
• 17:59
  Bob: And it's very, very uniform.
• 18:01
  Bob: It's almost exactly the same temperature all over the sky.
• 18:04
  Bob: The deviations from that 3,000 Kelvin black body are tiny.
• 18:11
  Bob: They're about one part in a hundred thousand.
• 18:14
  Bob: And these are the maps you see from these satellites.
• 18:16
  Bob: I'm sure you've seen the Planck map of the all-sky Planck map, which is this mottled red and blue structure.
• 18:23
  Bob: Those those fluctuations represented by the red and blue are tiny.
• 18:27
  Bob: They're, you know, one part in, I say a few parts in a hundred thousand.
• 18:31
  Bob: But they were absolutely crucial because they were the inhomogeneities in the universe which allowed gravity to collapse it in a non-uniform way.
• 18:42
  Georg: I mean, so this is what there would just be a gas cloud, right?
• 18:46
  Georg: There would be no.
• 18:47
  Bob: That was a g- yeah, it's a just a huge gas cloud, but slightly inhomogeneous.
• 18:51
  Bob: And of course, gravity acting on that uh will collapse certain the the the denser parts quicker than the uh the less dense parts.
• 18:59
  Bob: And so this was what started to form the structure in the universe.
• 19:03
  Bob: And after a couple of hundred million years, not a very long time, this formed the first stars.
• 19:10
  Bob: And this is what we're trying to see with the James Webb Space Telescope at the moment.
• 19:13
  Bob: That was one of its goals, was to see the first stars.
• 19:17
  Georg: Can I ask a little a quick question, right?
• 19:19
  Georg: Yeah.
• 19:19
  Georg: At this point, I think it makes sense.
• 19:21
  Georg: Um, when we think about this cosmic dust initially that then eventually formed stars, did this at the same time um form planets, or did the planets emerge from prior star structures?
• 19:34
  Bob: Um that's an interesting question to uh to address.
• 19:38
  Bob: I mean, of course, the the the material that was collapsing at that time was essentially pure hydrogen and helium.
• 19:46
  Bob: Because those were the only two elements that were formed in the Big Bang processes.
• 19:51
  Georg: It's not the only planet consists of, right?
• 19:54
  Bob: So you couldn't form a planet at that time, no.
• 19:56
  Bob: There's no way of uh forming a planet at that time.
• 19:59
  Bob: But the point was the hydrogen and helium was formed by by by by during the cooling of the universe, and this was a time which was between one and two minutes in the history of the universe.
• 20:15
  Bob: It was a very short time, of just a couple of minutes in the history of the universe, when the kinetic temperature was high enough to to actually fuse uh hydrogen into helium.
• 20:27
  Bob: And so there wasn't enough time.
• 20:30
  Bob: Then it then it cooled too much, and there wasn't enough time.
• 20:33
  Bob: And people thought originally that the all the elements were forged in the in the Big Bang, but that's not true.
• 20:38
  Bob: And George Gamoff actually was studying this at the time in the 40s, and uh realized that there wasn't enough time to form all the chemical elements.
• 20:48
  Bob: So the first stars had to form out of hydrogen and helium only, a little bit of lithium perhaps.
• 20:55
  Bob: Uh, but it's quite hard to form a star without the heavier elements, because the heavier elements allow the stars to cool as they collapse.
• 21:03
  Bob: You know, the bicycle pump effect.
• 21:05
  Bob: As you collapse a star, it gets hotter and hotter and hotter, and eventually it gets hot enough in the core to trigger nuclear fusion, which generates the energy uh which radiates as and eventually radiates as starlight.
• 21:18
  Bob: So there's a process here where you have to cool the star without the heavy elements, and it's difficult and slow.
• 21:26
  Bob: And that the consequence of that was it seems that most of the stars, or perhaps all the stars that formed first of all, were very, very massive and very, very bright, and emitted almost all of their energy in the ultraviolet, very little in the visible.
• 21:40
  Bob: It was all in the far ultraviolet, because the stars were so hot.
• 21:44
  Bob: Instead of being 6,000 Kelvins like the sun, they were 100,000 Kelvins.
• 21:50
  Bob: So they're really, really hot.
• 21:53
  Dave: So that's what the James Webb telescope is trying to find these stars, is it?
• 21:57
  Bob: It's trying to find these stars, and I think that we we probably won't see them directly.
• 22:01
  Bob: It's very hard to see them directly because at that time the universe was neutral.
• 22:06
  Bob: The hydrogen had electrons with it, and that was opaque to ultraviolet radiation.
• 22:11
  Bob: So all these forming stars were being shrouded in a mist, which we can't see through.
• 22:16
  Bob: But there's a peculiar, there's a peculiar process that goes on here which allows us to see these photons coming from these early stars, one step removed from their emission.
• 22:29
  Bob: They're radiated by the photosphere of these very hot stars, but we can't see them directly because the uh the intervening uh universe is opaque.
• 22:40
  Bob: And most of those photons will interact with the hydrogen atoms in the in the surrounding medium, and they will scatter off the hydrogen atoms.
• 22:50
  Bob: So it means that all of the most of the light that's coming out of the stars ends up as the fundamental line in in the hydrogen atom from the sec from the first excited level level to the ground state.
• 23:04
  Bob: And that line is called Lyman Alpha, after the guy who discovered the Lyman series.
• 23:08
  Bob: You maybe have heard the of the Barmer series of hydrogen lines in the visible spectrum, or the Lyman series of hydrogen lines is in the ultraviolet.
• 23:17
  Bob: So all these Lyman alpha photons, they bounce around and they eventually escape.
• 23:21
  Bob: They maybe bounce thousands of times before they get out of the mist.
• 23:24
  Bob: And then we see them, and we see Lyman alpha emission around these forming stars.
• 23:29
  Bob: But actually, they can't they can get out more quickly, and they do this by exciting the hydrogen atom up to the first excited state.
• 23:42
  Bob: And there is a way that that that hydrogen atom in in one of its forms of the first excited state, the most common form, cannot transition back to the ground state because of a quantum mechanical selection rule.
• 23:58
  Bob: Um, so you're going from a singlet state of hydrogen to another singlet state of hydrogen, and it doesn't work.
• 24:04
  Bob: But very occasionally uh you can break the rules of quantum mechanics, and that and that that excited hydrogen atom can decay by emitting two photons instead of one.
• 24:17
  Bob: And it's called two photon emission, and we can observe that with telescopes, the James Webb.
• 24:25
  Bob: We observe that with the telescope now, and that's we see that light coming out, and that's probably light that was emitted by the very, very young stars, which we may never see directly, but it's the most direct method we have of seeing the light coming from the first stars.
• 24:41
  Bob: And we can see that very clearly with the James Webb now, and we can characterize it and then.
• 24:46
  Bob: Yeah, yeah.
• 24:52
  Bob: It's uh yes, it's a it's it's a well it's a well-known process which was discovered in the 20s, I think, uh 1920s.
• 24:59
  Bob: It is a, you know, it's one of these many ways in which there's strict quantum mechanical selection rules don't always work strictly because you can get around them in other ways.
• 25:09
  Bob: And by emitting two photons, and these two photons, uh, the s the sum of energies of these two photons is exactly the same as the energy that the single photon would have if it if it were able to escape.
• 25:22
  Bob: Anyway, that's uh that's a bit of a detail, but it's but it's quite an interesting thing.
• 25:26
  Bob: And it brings us to the you know the whole question of the origin of the first stars and how they start populating the periodic table.
• 25:34
  Bob: And they will start doing this very, very quickly because these stars are so luminous that they run out of life, they run out of their nuclear fuel in perhaps just a few million years, not 10 billion years like the sun.
• 25:50
  Bob: It happens very quickly.
• 25:51
  Bob: So these stars go off like flash bulbs in the early universe.
• 25:54
  Bob: And when they explode as supernovae at the end of their lives, they distribute their fusion products into the surrounding medium.
• 26:03
  Bob: And this this goes into the generation uh into the formation of the next generation of stars.
• 26:08
  Bob: So gradually you build up the abundance of the heavier elements as you cycle through generations of stars through the history of the universe.
• 26:18
  Bob: And of course, there are many generations of stars going on now.
• 26:23
  Georg: And so this is stars in the future, like in the very distance future, who are very different than our current stars, like exposed.
• 26:29
  Georg: Well, basically process.
• 26:32
  Dave: If you're enjoying Sunlight Matters, make sure to subscribe and leave us a review on your favourite podcast platform.
• 26:39
  Dave: You can also search Sunlight Matters on Google to find more episodes, guest information, and further insights about sunlight analysis, solar exposure, and the way light shapes our spaces.
• 26:54
  Bob: Well, the universe will end up with everything being an iron because it's the most stable element.
• 26:59
  Bob: But that'll take a very, very long time.
• 27:02
  Bob: But the point about the generation of stars, it happened, it happened very quickly in the early universe.
• 27:08
  Bob: So these these stars mostly live very short times, so there were many cycles per unit time in the early universe.
• 27:15
  Bob: And so very quickly, uh the abundance of the heavier elements, carbon, nitrogen, oxygen, silicon, magnesium, iron, all those things, the heavier the the elements heavier than iron are different, slightly different story, but you know, all part of the same process, but a slightly different story.
• 27:33
  Bob: So even the very earliest stars that we see, if they're not absolutely the first generation of stars, those early stars will contain these common elements, oxygen, carbon, nitrogen, magnesium, and so on, neon.
• 27:51
  Bob: We see these.
• 27:52
  Bob: All the spectra of the early stars we observe with the James Webb Space Telescope, and could indeed do with Hubble, they contain these elements.
• 28:00
  Bob: They may be only at 1% of the level they are in our current universe, but they're easy to see, so we can see them.
• 28:09
  Bob: So we can we can map the we can map the development of the periodic table by looking at the spectra of these very early stars, or at least the nebulae around them.
• 28:20
  Bob: And so what happens is that the these stars are you know going through their generations, they're emitting lots and lots of starlight, and the amount of starlight they emit is intimately associated with the abundance of the elements they're producing.
• 28:40
  Bob: So it takes nuclear fusion to produce the periodic table, and it's the same nuclear fusion that generates the starlight.
• 28:48
  Bob: So there's essentially a one-to-one correspondence between the growth of the amount of starlight in the universe and the growth in the abundance of the elements.
• 28:57
  Bob: And I I showed this cartoon, which actually showed these lines overlapping.
• 29:01
  Bob: I mean, it's meaningless in the way that they overlap, but you know, they they they develop in in in concept with one another.
• 29:08
  Bob: And of course, the the the starlight is the starlight is what allows these stars to remain stable while they're burning nuclear fuel.
• 29:19
  Bob: Because if they just burn nuclear fuel and they couldn't get rid of all this energy they were producing, uh they would blow up.
• 29:26
  Bob: And so it's the starlight which uh migrates from the core where the temperatures are very high, you know, millions and millions of degrees, these photons uh they they they they transition through the whole body of the star and eventually reach the surface.
• 29:43
  Bob: They don't reach the surface as the same photons, because obviously around the middle they're gamma ray photons, they're very energetic.
• 29:49
  Bob: But as they as the energy um seeps through the the star to reach the surface and get radiated, uh you get lower and lower energy electrons.
• 29:59
  Bob: Uh uh photons, sorry.
• 30:01
  Bob: And so the photons that are radiated that are radiated from the surface of the star are the waste energy uh from the nuclear fusion in the core.
• 30:13
  Bob: So, and this is where I try and introduce the concept of entropy, because entropy is is basically the waste energy that you have to produce if you organize anything.
• 30:24
  Bob: And you have to organize your bodies into what we call homeostasis in order to keep yourselves alive.
• 30:31
  Bob: And the energy you use to build that order in your body is the energy that you ingest from food.
• 30:40
  Bob: In a star, it's the energy you you get from nuclear fusion in the cure, in the core, but in your body, it's the food that you eat.
• 30:48
  Bob: And most of the food that you eat generates waste heat.
• 30:53
  Bob: So if you eat, if you eat 2,000 calories a day, you'll generate about 90 watts of waste heat.
• 31:02
  Bob: And only about 5% of that will be used as useful energy to allow you to think and move around and so on.
• 31:08
  Bob: So most of the food you eat ends up as waste heat, which you have to get rid of by sweating or radiating or whatever, uh lying on a cold sheet of metal or something, whatever, to take your waste entropy away.
• 31:22
  Bob: Now, this is when I realized, and other people have realized this as well, but the the the close analogy between the basic energetics of a star and the basic energetics of a living being, anything on in the biosphere.
• 31:36
  Bob: And that is you you need a source of energy.
• 31:39
  Bob: In a star, that's nuclear fusion.
• 31:42
  Bob: In a life form, it's the food that you eat.
• 31:46
  Bob: In the sun, uh in photosynthesis, of course, photosynthesis plants have to generate their bodies, and they do this in their mitochondria in the way that animals do.
• 32:00
  Bob: So they have an animal component in them as well.
• 32:03
  Bob: Uh but they they they produce the food as well in plants by photosynthesis.
• 32:08
  Bob: But you know, if you have a so if you have a star, you have energy coming in, you have starlight going out as your waste product.
• 32:19
  Bob: Now, for a life form, that starlight is actually a highly ordered nutrient for you.
• 32:28
  Bob: It's a very powerful nutrient, and you know, the the the products of photosynthesize attest to that.
• 32:35
  Bob: And we're arguing that we need to uh absorb this starlight as well to metabolize our food, not only to generate it in plants, but also to metabolize it in animals and fungi and so on.
• 32:48
  Bob: So there's a very close analogy between the energy flow through a star, it's producing waste heat, which we call waste entropy, uh, which I'll explain in a bit in a moment, but uh uh uh and in in a in a body, in your body, uh you're ingesting food, which is allowing you to maintain the order in your body, which allows you to live.
• 33:14
  Bob: If you didn't have that order, you come into thermodynamic equilibrium with your surroundings, which would be mean you were dead.
• 33:21
  Bob: So you you eat and you eat in order to maintain your order inside your body.
• 33:26
  Bob: And this was Schrdinger's famous statement.
• 33:29
  Bob: You eat order in order to maintain the order in your body.
• 33:33
  Bob: This is why you need highly ordered foods.
• 33:36
  Bob: And incidentally, and I'm not going down this route, incidentally, ultra-processed foods have no order.
• 33:44
  Bob: Low order.
• 33:46
  Bob: They have very low order.
• 33:48
  Bob: No, they have very high order.
• 33:49
  Bob: They have no they're completely disordered.
• 33:51
  Bob: Sorry.
• 33:52
  Bob: They have they have very low state of uh order.
• 33:55
  Bob: Yeah, and this is where we this is the common confusion we get we're talking about entropy.
• 34:00
  Bob: Schrdinger introduced the concept of negative entropy, which means highly ordered.
• 34:05
  Bob: Lots of entropy means you're completely disordered.
• 34:08
  Dave: Yeah, yeah, yeah.
• 34:08
  Dave: No, that's which is which is f- I mean, I presume like I I picked a couple of apples off my tree um this morning.
• 34:16
  Dave: I presume an apple is a very highly ordered thing.
• 34:19
  Bob: Yes, exactly, exactly.
• 34:20
  Bob: Structure.
• 34:21
  Bob: The structure is very important, the cellular structure, the fact that it contains things like amino acids, an ultra-processed food, doesn't contain anything that's structured.
• 34:30
  Bob: It's just pure chemicals.
• 34:31
  Bob: So it's it we call it maximum entropy food.
• 34:34
  Bob: You couldn't make it more useless as food if you tried.
• 34:38
  Georg: And isn't it like that?
• 34:39
  Georg: These like very natural foods are just carrier of starlight and and you ingest it and then you bring that back of that light.
• 34:48
  Bob: Yes, they're they're carriers of order.
• 34:49
  Bob: And the sugars you produce are highly ordered because they they're very energy rich.
• 34:54
  Bob: So they're highly ordered foodstuffs.
• 34:56
  Dave: So I'm I mean, really very, very interesting.
• 35:00
  Dave: I mean, the other point that you made in your presentation was about the cooling universe and how you know the the reality is is we need that cool universe in order to get rid of the heat.
• 35:14
  Bob: Exactly, yes.
• 35:15
  Bob: I mean, that's what that that that that's really the point of me showing this cosmic microwave background, because at the moment uh the cosmic microwave background has moved from being 3,000 Kelvins to being 2.75 Kelvins.
• 35:30
  Bob: So it's very cold.
• 35:32
  Bob: And that cold, that coldness surrounding us is absolutely crucial because if we didn't have that cold surface or volume to radiate into, we couldn't use energy to create order in our lives because there would be no way to get rid of the waste heat.
• 35:53
  Bob: And incidentally, this is a good way of introducing the idea of being inside.
• 35:58
  Bob: Now, we're all sitting in a room where I guess the temperature of the walls is around 20, 21, 22 centigrade, and the energy of our bodies, internal energy of our bodies, the internal temperature of our bodies is 37 degrees.
• 36:15
  Bob: So there's not a very big difference between the temperature of our surroundings and the temperature inside our bodies.
• 36:22
  Bob: And the result of that is that we can only ever produce, when we're in a room like this, about 5% of our ingested food energy.
• 36:32
  Bob: We can only ever produce about 5%, which is useful, which is what allows us to do stuff.
• 36:39
  Bob: The rest is waste heat we have to get rid of.
• 36:42
  Bob: And getting rid of waste heat from 37 degrees to 22 degrees is not very efficient.
• 36:49
  Bob: If our room was at 5 centigrade, we would probably be able to get, well, we would be able to generate about twice as much energy from our food than we can.
• 36:59
  Bob: And what happens if you if you walk outside from, if I walk outside now, I mean some of the sky is blue, if I walk out under a blue sky and I point a radiative thermometer, I have one here, one of these radiated thermometers, if I point that at a clear blue sky in the zenith, it'll read minus 40 or minus 50 centigrade.
• 37:22
  Bob: So much, much colder than your surroundings in a room or on the ground, or normally on the ground.
• 37:32
  Bob: So this is why uh one of the reasons why it's so important to get outside is to expose yourself to some part of your environment which is cold, because it gives you much more energy.
• 37:46
  Bob: And I think, in a way, you asked about going broad and deep.
• 37:50
  Bob: You know, all the development, the Industrial Revolution development happened at mid-latitudes.
• 37:57
  Bob: We know that happened in Britain, mid-latitudes.
• 38:00
  Bob: And think of these navies that went to build the canals and to build the railways.
• 38:06
  Bob: They were eating something like 8,000 calories a day, and they were producing huge amounts of energy to shovel dirt uphill and so on to build embankments and dig canals and so on.
• 38:16
  Bob: They would not have been able to do that in the tropics.
• 38:19
  Bob: You could not have had an industrial revolution like that in the tropics, because you could never have used people to produce enough energy to do that.
• 38:27
  Bob: So having cold surroundings is enormously beneficial.
• 38:31
  Bob: And I mean, I've noticed this absolutely viscerally.
• 38:35
  Bob: We've had a very hot summer, and you know, when it's really hot, you go for a walk outside and you get exhausted.
• 38:41
  Bob: But yeah, over the last few days, when it's been quite cool outside, you bounce outside and you walk around thinking this is great.
• 38:48
  Bob: And this is pure thermodynamics.
• 38:50
  Bob: It's simply the Carnot cycle.
• 38:53
  Bob: You know, the the efficiency of uh you've muted yourself, Dave.
• 38:58
  Bob: The efficiency of generating energy in your body is dependent on the temperature difference with your surroundings.
• 39:08
  Dave: And it it's it's it's I mean, uh it it it is amazing to think.
• 39:13
  Dave: I mean what what one I I mean I'm bouncing here, but the imp that what you see is that there is a definite order to like the way that the universe started, what then happened, and you can almost draw a straight line, and you've you've you've done this actually, you've to life as well.
• 39:36
  Dave: There's a straight line.
• 39:38
  Dave: So we we are there was a a map of order, which immediately makes me think that well, we can't then be the only things that have ended up like living th we can't be the only living things in the universe because there's a straight line to all that that we're we're part of this line.
• 40:01
  Dave: I mean, I'm I'm sorry, it's just a very random thought that I have.
• 40:04
  Bob: No, it's uh I I'll focus that thought slightly and say, yes, in my opinion, um the the the things we're talking about at the moment will be true of any at least Earth-like planet which has carbon-based life on it.
• 40:20
  Bob: All of these scaling laws will be the same.
• 40:23
  Bob: Because they're related, they're so closely related to the properties of the star and uh and and the properties of the of the elements that form the periodic table.
• 40:34
  Bob: And so I think with the the the picture we're painting at the moment would essentially apply to any planet in the universe which had um biological life on it.
• 40:48
  Dave: So that biological life is m probably going to be similar to biological life on Earth because it's like it just it sort of feels like there's a a map, there's a map there.
• 41:02
  Bob: Well, this is the this is the common scaling law, yes, which applies to all of life on the planet and uh would apply to all life on on any planet, I think.
• 41:12
  Bob: It's uh it's physics.
• 41:14
  Bob: It's just physics.
• 41:15
  Bob: It's nothing to do with DNA and biology.
• 41:18
  Bob: So it's physics.
• 41:20
  Bob: It's energy flow.
• 41:22
  Dave: I and I'm sorry, I just I just had that thought and was w, you know, bounced around on.
• 41:28
  Dave: I I really would like to go back and talk about our sun, though, because you know what what what what how big is our you know, you know, just some basics about the sun.
• 41:40
  Dave: Like how does it compare to other suns out there?
• 41:44
  Dave: Um it's obviously very special to us because you know top ten of best stars in the closing.
• 41:52
  Dave: I'd say top top top one of best stars in our solar system.
• 41:56
  Dave: So I mean, and it and it uh I I saw Brian Cox did a brilliant program on the planets, but he just one of the things that really fascinated me was just the sheer scale of influence of the sun on the solar system.
• 42:12
  Dave: He he he basically he had to drive for kilometers.
• 42:16
  Dave: You you know, he sort of said, assume I take two steps and that's two from a rock and that's the earth.
• 42:24
  Dave: He then had to drive for almost kilometers before he said this is the end of the impact of the sun on the solar system.
• 42:32
  Dave: So that's just it was just you, you know, because we've got you here, a good chance to get some basic facts on the sun.
• 42:39
  Bob: Well, that's uh I won't do numerical facts because I unless unless they're necessary, because people can easily look those up, okay?
• 42:46
  Bob: But I'll I'll paint the story.
• 42:48
  Bob: The thing is, when you form a star out of an interstellar medium, you have this chaotic molecular cloud around you, which contains molecules and atoms and so on, and it's floating around in in interstellar space, and there will be some effect which triggers some part of that cloud to collapse into a star.
• 43:08
  Bob: And you often collapse stars into clusters because you collapse many stars more or less at the same time.
• 43:14
  Bob: And it's gravity, of course, that pulls these stars together and and and fragments them into individual stars.
• 43:22
  Bob: As the gas cloud collapses, there'll be some turbulence in the gas cloud.
• 43:27
  Bob: There'll be motions, you know, flows and and motions, small, small motions, but they'll they'll they'll they'll be there.
• 43:34
  Bob: And as you collapse down to having a what you would recognize as a forming star, uh a dense collapsing gas cloud, um the the motions, the random motions will assert themselves as a net angular momentum.
• 43:54
  Bob: So the star will start to spin with a particular axis as it as it collapses.
• 44:01
  Bob: And like a ballet dancer uh spinning round, you know, if you as it collapses, the spin speeds up.
• 44:10
  Bob: Because you you have to conserve angular momentum, and the only way you can certain can conserve angular momentum if you start off in a large scale and you're getting to a small scale is to rotate faster.
• 44:23
  Bob: And so all stars will end up with an excess of angular momentum, which hasn't which is not able to form in it fall into the star.
• 44:32
  Bob: It's got too much momentum.
• 44:34
  Bob: So it forms a disk around like a like Saturn's disk.
• 44:38
  Bob: It forms a disk around the star.
• 44:40
  Bob: And we call this a protoplanetary disk.
• 44:43
  Bob: And we see these now.
• 44:45
  Bob: We can we can m we can we can image these.
• 44:48
  Bob: Hard to do with optical telescopes, uh, much easier to do with some millimeter telescopes working at longer wavelengths where the star is very dim, so you don't get this enormously bright light source in the middle.
• 45:00
  Bob: And I showed in my talk, I showed you a number of images of these protoplanetary disks.
• 45:06
  Bob: And those disks contain um the less volatile uh elements.
• 45:13
  Bob: The uh, I mean, that the hydrogen will probably escape as soon as it warms up a bit.
• 45:19
  Bob: Uh, but the it can that you of course you can collapse hydrogen into massive planets, but you can't collapse hydrogen onto the Earth because it's too small.
• 45:29
  Bob: We lose the gaseous hydrogen uh uh from our atmosphere very quickly.
• 45:35
  Bob: Anyway, so every star will have a protoplanetary disk in some form or another, and that's the material from which the planets are formed.
• 45:45
  Bob: And that material contains the whole spectrum of uh elements in the periodic table that were present present in the molecular cloud, including the molecules that are formed in interstellar space.
• 46:02
  Bob: So this is stardust which collapses into a planet.
• 46:06
  Bob: And you get fractionation there.
• 46:09
  Bob: You say you don't keep all the hydrogen, you keep very little of the helium because the Earth is not big enough to have strong enough gravity to hold the atoms into the the atoms of are moving too fast too.
• 46:21
  Bob: They move faster than escape velocities, so they escape.
• 46:25
  Bob: But we end up with the heavier elements on the planet, and they form the material from which you can generate the next scale of complexity, which is biological evolution.
• 46:41
  Bob: And so, you know, one's now generating a an analogue of a star, but on the planet in the form of life.
• 46:51
  Bob: So life is developing out of this star dust using the elements, using the organic uh atoms that you need carbon, nitrogen, oxygen, but also the other elements that are necessary for normal life, like some of the enzymes and so on, all of that is present on the planet.
• 47:08
  Bob: And you're organizing that, those, those elements into self-organizing chemical mixes, which you know gradually develop in into life.
• 47:18
  Bob: And so that life then operates on the same plan as the star.
• 47:24
  Bob: You have a source of energy, uh, which is derived from sunlight.
• 47:29
  Bob: Uh, you have a source of material, which is the stardust from previous generations of stars.
• 47:35
  Bob: Um, by this time, the universe is fairly rich in heavier elements because the the bulk of the star formation uh happened about 10 billion years ago.
• 47:44
  Bob: And we're not producing nearly as many star new stars now as the universe was at that time.
• 47:49
  Bob: So, you know, all the the the periodic table is very well populated now with elements for enabling life to form.
• 47:58
  Bob: And so then we develop life forms, which have a source of energy, they have a source of materials, and they have a way of radiating their waste heat into outer space.
• 48:11
  Bob: And they can't do it because they're on the surface of the planet, they can't do it directly to the three Kelvins of outer space.
• 48:19
  Bob: They have to go via the atmosphere.
• 48:22
  Bob: And there are windows in the atmosphere which are relatively transparent.
• 48:26
  Bob: They have very little absorption in them.
• 48:29
  Bob: And it's these windows that are used to radiate the excess waste heat from all of this complexity generation associated with life into outer space.
• 48:40
  Bob: And the main one of that is between seven and fourteen microns wavelength, and that's where these radiative thermometers work.
• 48:48
  Bob: Because the, you know, seven to fourteen microns is where the black body radiation of the earth is.
• 48:56
  Bob: So the earth is radiating its the all the heat it gets from the sun, that that energy is conserved somehow, and it's continuously raining on us from the sun.
• 49:07
  Bob: You have to get rid of that energy, otherwise your earth is going to heat up.
• 49:11
  Bob: So you get rid of that mostly through this window between seven and fourteen microns goes out into our outer space and is is lost and enables the earth to r retain its temperature stability.
• 49:26
  Georg: So what what the the micron wavelength you describe, what what electromagnetic frequency are we talking here about?
• 49:34
  Georg: Is this like infrared or what what is it?
• 49:36
  Bob: This is mid-in- yeah, it's mid-infrared.
• 49:38
  Bob: Okay.
• 49:39
  Bob: So it's now I say it's the temperature, it's it's the window within which these thermometers.
• 49:45
  Bob: And the thermal imaging cameras work in the same in the same range.
• 49:49
  Bob: You know, any thermal imaging camera will be looking at the radiation from the earth and from you and me at those wavelengths.
• 49:57
  Bob: And those wavelengths, obviously, you that it doesn't generate, we don't generate wavelengths in the visible.
• 50:03
  Bob: Well, actually we do in the body.
• 50:05
  Bob: There are biophotons that are generated inside the body, but then they're not they they're not very bright, they're very rare.
• 50:11
  Bob: But um, so we you know, we have to have a way of radiating our waste entropy into outer space.
• 50:18
  Bob: And this whole climate change stuff that we're talking about, it's a very inappropriate name for a phenomenon which is actually very basic.
• 50:28
  Bob: Climate change is is a symptom of what's going on in the earth at the moment.
• 50:32
  Bob: It's not the cause, it's a symptom.
• 50:34
  Bob: And what we're doing is we're closing this window a little bit, the window through which the earth radiates its excess heat, by and uh because one of the main absorptions in this window is carbon dioxide.
• 50:47
  Bob: And there are other absorbers, water, methane, and and so on, in the window.
• 50:54
  Bob: So we're closing that window a little bit, and the earth reacts by becoming hotter.
• 51:00
  Bob: It establishes a new equilibrium.
• 51:03
  Bob: In order to radiate the its heat away, it it it it gets hotter.
• 51:09
  Georg: Seems like a super sensitive system.
• 51:11
  Georg: I have a question, because there are some um thoughts of dimming Earth's atmosphere to to let in less sunlight.
• 51:19
  Georg: Wouldn't that be kind of counterintuitive to what you're describing?
• 51:22
  Bob: Like couldn't that also Well I mean that that that is a potential solution.
• 51:25
  Bob: You uh I mean you are you either find a way of getting rid of your waste heat better, or you stop so much heat coming down from the sun.
• 51:36
  Bob: So yeah, if you shine so if you if you reflect some sunlight.
• 51:40
  Bob: This is why this is why you get global cooling after the meteor impact that destroyed the dinosaurs.
• 51:50
  Bob: You know, you'd think it would get very hot.
• 51:52
  Bob: Well, it did get hot for a short period of time, but then it got really cold because the sunlight was being reflected from the this this the top of this gas cloud.
• 52:01
  Bob: And uh this is what you know the nuclear winter is.
• 52:04
  Bob: It's uh you know, you generate you generate lots of stuff in the atmosphere which reflects light out, so it cools.
• 52:11
  Bob: So there's a it's a it's a complex interlinked system, you know, it's a series of feedback loops, but what we're doing is stopping the Earth from radiating all the energy that it's generating.
• 52:24
  Bob: And of course, you know, you and I will only radiate 100 watts, call it 100 watts, 90 watts or whatever, depending, you know, depending how much we eat, but we'll we'll radiate 100 watts.
• 52:38
  Bob: Now if you have a city with a transport system and infrastructure and air conditioning and heating and so on, and you share that all the energy you're using to drive the the functioning of the city, if you share that out amongst the people who live in the city, it means that you're using, you're radiating much more than 90 watts.
• 53:09
  Bob: I think uh in Jeffrey West's book, I think he says we we in a big city will be responsible for something like 11 or 12 kilowatts of energy, which is way more than what what uh than what we're radiating just as a biological system.
• 53:27
  Bob: And this is why, you know, the planet that we have and we're building at the moment is unsustainable.
• 53:36
  Bob: It's demonstrably unsustainable because we're generating we're generating so much energy in our cities that we're making um I don't want to go into details of the scaling law, but the the the scaling law for biology is what's called sublinear, sublinear.
• 53:55
  Bob: The bigger you are, the more efficiently you use energy.
• 53:58
  Bob: So if you take you you you'd have to take many, many mice in order to uh uh to make up the mass of a of a human, but the energy used by those many mice will be much bigger than the mass used by a human.
• 54:16
  Bob: So the scaling law is called sublinear.
• 54:19
  Bob: And and this means that we can live comfortably on the photosynthetic products that's happening while we're living.
• 54:26
  Bob: So we don't have to rely on fossil fuels.
• 54:29
  Bob: Now, if you build cities, it's a superlinear scaling.
• 54:34
  Bob: And so you can't live on the products of photosynthesis while you're living.
• 54:40
  Bob: So basically you have to burn the planet in order to live.
• 54:43
  Bob: And this is the dilemma that we have.
• 54:46
  Bob: And I think looked at in this energetic way, it's a very simple energetic way of looking at the whole question of um global warming.
• 54:57
  Bob: But to only think of it in terms of climate change is muddying the waters, because climate change is very complicated.
• 55:04
  Bob: And it doesn't all happen at once, it doesn't all happen in the same direction.
• 55:07
  Bob: It's a very complicated system.
• 55:08
  Bob: And this gives the deniers lots of excuses for saying it's all rubbish.
• 55:13
  Bob: But if you look at it purely from the thermodynamics, from the energy flows, it's absolutely obvious and c and undeniable that we're living unsustainably at the moment.
• 55:28
  Dave: Interesting.
• 55:29
  Dave: Interesting.
• 55:31
  Dave: Well, listen, I can we go back to uh a bit about the sun as well.
• 55:36
  Dave: You know, so we we we sort of um collected.
• 55:42
  Bob: Yeah, let's go back to the sun.
• 55:44
  Bob: Okay, so the sun, the thing is the sun that for this purpose, there are two types of stars.
• 55:51
  Bob: There are the very massive stars, uh O stars and B stars and so on, uh, which are very blue and very hot.
• 55:58
  Bob: And there are cooler stars like the sun, and we go down to m dwarfs and so on.
• 56:03
  Bob: So the whole range of stars, and the temperature of those stars depends on how massive they are.
• 56:09
  Bob: So if we have we're we're one solar mass by definition, we can go down to smaller stars, uh K stars and m stars and so on.
• 56:19
  Bob: They're lower mass, we go right down to about a tenth, roughly a tenth of the solar mass before we uh unable to have nuclear fusion in the course.
• 56:28
  Bob: But we can also go up the other way, we can go up to maybe 40 times, 50 times the mass of the sun, which we have around us, as these OB stars they're called.
• 56:39
  Bob: They're very bright hot stars.
• 56:40
  Bob: They're very rare, but they're very extremely bright.
• 56:43
  Bob: But in the early universe, we could go up to hundred solar masses or so.
• 56:47
  Bob: So, and this the the if you s if you plot these stars on what's called in astronomy the Hurz from Russell diagram, or the colour magnitude diagram, you're basically plotting the luminosity, the brightness of the star on the y-axis, and the mass of the star on the on the x-axis.
• 57:04
  Bob: And that forms what we call a main sequence.
• 57:08
  Bob: So stars of low mass fall down here.
• 57:12
  Bob: They have they have, well, let's put it this way around, doesn't matter.
• 57:15
  Bob: These are the low mass stars, they're very dim, and the high mass stars are very bright.
• 57:20
  Bob: So there's a sequence.
• 57:22
  Bob: It's not necessary, it depends on how you plot it, but it's not necessarily a straight line, but it's a well-defined sequence.
• 57:28
  Bob: And you see that on all these astronomical diagrams called the Erstram-Russell diagram.
• 57:33
  Bob: They're normally plotted as magnitude versus color, but it's essentially energy production rate against mass.
• 57:43
  Bob: So there's a change in the way that the stellar atmospheres work, somewhere in the middle of this diagram, just above the temperature of the sun.
• 57:54
  Bob: If you're in a very hot star, all the hydrogen in the atmosphere is ionized.
• 58:00
  Bob: So you get three protons and you get three electrons.
• 58:03
  Bob: And that produces its own character of mistiness.
• 58:09
  Bob: You get mistiness from scattering of light from electron to electron, and that's quite a powerful scattering process.
• 58:16
  Bob: When you get to a temperature like the sun, the sun's atmosphere is not hot enough to ionize hydrogen.
• 58:24
  Bob: And so the hydrogen atom is generally neutral.
• 58:28
  Bob: But you still get plenty of electrons because you get that from ionizing the heavier elements, the metals in particular, sodium, magnesium, silicon, and so on.
• 58:37
  Bob: You can ionize those metals quite easily.
• 58:40
  Bob: So we're sitting, we in the sun have an atmosphere of basically mostly neutral hydrogen, but lots of electrons coming from the metals.
• 58:52
  Bob: And there's a very particular property of the simple hydrogen acid, in that you have one proton and one electron going around it, and the positive charge of that proton is not very well shielded from its environment by this single electron.
• 59:11
  Bob: You know, the single electron's going all over the place, but it can't shield that proton, the electric field from the proton very effectively.
• 59:19
  Bob: So if another electron comes up, it can attach itself to the hydrogen atom and make what's called a hydrogen negative ion.
• 59:27
  Bob: And this is this is extremely important for the atmosphere of the sun.
• 59:33
  Bob: It's called the H-minus ion.
• 59:35
  Bob: It's just astronomical language.
• 59:37
  Bob: It would be called something different in chemistry and something it'd be called the the anion, the hydrogen anion in chemistry, I guess, and something else in biology.
• 59:47
  Bob: But this hydro this negative hydrogen ion, this H minus, uh, is responsible for the mistiness of the solar atmosphere.
• 59:59
  Bob: In the visible and near-infrared part of the spectrum.
• 1:00:04
  Bob: So it determines how deep you have to look into the atmosphere to see the effective surface of the sun.
• 1:00:14
  Bob: And in the visible part of the spectrum, where you can easily knock this electron off the hydrogen, the hydrogen ion, because the photons have more energy than three-quarters of an electron volt, which is the what's called the dissociation energy of the hydrogen ion.
• 1:00:34
  Bob: If you fire a photon acid with an energy of more than 0.75 electron volts, it will ionize it.
• 1:00:42
  Bob: It will dissociate the ion.
• 1:00:47
  Bob: And that's what produces the opacity in the visible part of the spectrum.
• 1:00:51
  Bob: So we only look so deep in the visible part of the spectrum, and that determines, principally determines what we call the effective temperature of the Sun, which is the black body that fits best the overall energy distribution coming from the Sun.
• 1:01:06
  Bob: But if you go to 0.75 electron volts, where you lose the opacity from the H minus ion, the opacity suddenly drops to a much lower level, and you look deeper into the solar atmosphere.
• 1:01:20
  Bob: And because of the structure of the atmosphere, the temperature is higher.
• 1:01:24
  Bob: The deeper you go into the atmosphere, the higher the temperature.
• 1:01:28
  Bob: And so in the infrared at around 1.6 microns, you're reaching the minimum in the solar opacity and you're looking deeper into the star.
• 1:01:39
  Bob: So you get an excess of energy around that wavelength coming out of the sun.
• 1:01:43
  Bob: And I showed that in the diagram in the talk, where you get the Planck function, which is the thermal emission from what we call a black body, a perfect emitter.
• 1:01:54
  Bob: The sun is not quite a perfect emitter.
• 1:01:56
  Bob: It's not quite a Planck function, but it's pretty close.
• 1:01:59
  Bob: And there's this big sort of mountain-like peak at 1.6 microns, which is where you're looking deeper into the atmosphere of the Sun.
• 1:02:08
  Bob: And you know what triggered my interest in this, uh, and I think has not been seen by the biologists, because they don't know about this H minus ion in the in the solar atmosphere.
• 1:02:20
  Bob: Why would they?
• 1:02:21
  Bob: And we taught it in first-year astrophysics, but if you don't do first-year astrophysics and you don't know anything about it.
• 1:02:26
  Bob: Anyway, this um this peak in the spectrum coincides almost exactly with the energy, a special kind of energy in all of life, which is called the uh activation energy.
• 1:02:44
  Bob: And it's the uh the energy which is pertinent to this metabolic theory of scaling, which is talked about by West and so on.
• 1:02:52
  Bob: And what it is, it's you know, if you have if you have a bag of chemicals at a certain temperature, and the temperature is high enough that these chemicals can react with one another, all the chemicals would just react with one another, hickledy-pickledy, and they'll all end up at the the lowest energy state.
• 1:03:10
  Bob: Now, in our bodies, we've got a complex system of homeostasis, all these chemical and physical chemical reactions going on to keep us alive.
• 1:03:22
  Bob: And it takes energy to to drive that system.
• 1:03:27
  Bob: And it turns out that there's there's an energy which delimits the separation between you just getting chemical reactions going on Hickledy Pickledy, and a state where you can actually control where and when which chemical reactions happen.
• 1:03:47
  Bob: And so this is represented by an activation energy.
• 1:03:51
  Bob: And this is uh has the the energy corresponds to quite a high temperature, much higher than our body temperature.
• 1:04:00
  Bob: And it's this activation energy which is the barrier that the process of life has to overcome in order to perform any chemical reactions.
• 1:04:13
  Bob: In order to get the electron uh from your food down the electron transport chain in the mitochondrion and produce the ATP, the energy from the chemical energy uh that drives your cells, you have to control the way the electrons go down that electron transport chain.
• 1:04:32
  Bob: And you control that by having energy barriers which are just the right size, that they can you can overcome them, but you don't overcome them all in an instantaneous flood.
• 1:04:45
  Bob: You have you you overcome them in a controlled manner.
• 1:04:48
  Bob: And it turns out the activation energy, which has been determined by biologists over all life forms from bacteria to the blue whale, the average activation energy is around 0.7 electron volts.
• 1:05:01
  Bob: And that's almost exactly the same as the peak photon flux coming from the sun.
• 1:05:09
  Bob: Now, when I when I realized this, I thought that's not an accident.
• 1:05:14
  Bob: Life has evolved over four billion years to tune itself so that it has its its its structure.
• 1:05:24
  Bob: The structures that you have to maintain your homeostasis are tuned to an energy source which allow can allow you to overcome these barriers, but in a controlled manner.
• 1:05:37
  Dave: But but but it but but again, that I mean that's an incredible like again when you think about it, it is so obvious that life would have formed under the sun and would have, but it it it's so what isn't obvious and what doesn't seem to nobody seemed to kind of have connected until you know you and a few others very recently is that absolute connection between some of the it's remarkable.
• 1:06:08
  Dave: You know, and and that I guess the importance of that is so when you say we're killing ourselves by being indoors, yeah, you're not figuratively saying it, you're literally saying it because we need the sunlight to trigger these things, you you know, for us to live life.
• 1:06:30
  Dave: And if we're not getting those signals, then things are gonna go awry very quickly.
• 1:06:34
  Dave: Yeah.
• 1:06:36
  Bob: I'm not stabbing you in the back and killing you instantly.
• 1:06:39
  Bob: No, we're making cool.
• 1:06:40
  Bob: We're making people age faster.
• 1:06:43
  Bob: Because because you you're you're you're you're speeding up, you're you're losing the ability to repair your mechanisms.
• 1:06:53
  Bob: You need to repair these mechanisms, you need photons of about 0.7 electron volts in order to synthesize proteins and maintain your mitochondrial health and structure, generate new mitochondria and so on.
• 1:07:08
  Bob: And this is what we're learning from the experiments that Glenn Jeffrey and his people are doing in London.
• 1:07:13
  Bob: They're showing that, you know, if you if you if you shine this light on people, we're doing humans, we're not doing mice, uh, uh, we're doing we're doing humans.
• 1:07:26
  Bob: If you shine light on people, their mitochondria work better, they metabolize quicker, and the positive effects of that, which is an instantaneous effect to some extent, the effects of that last for much longer than you're shining the light on them.
• 1:07:42
  unknown: I.
• 1:07:43
  Bob: There's a long-lasting tail of this, which extends over over days and weeks.
• 1:07:47
  Bob: And this, we believe, is the turnover time of generating new new proteins and new mitochondria and so on.
• 1:07:55
  Bob: So there are two effects of the light.
• 1:07:57
  Bob: One is um one is an almost instantaneous effect of producing ATP more quickly, by allowing, you know, I used the idea of lizards going out and basking themselves on a rock in in the morning, in the morning sun.
• 1:08:11
  Bob: You know, the biologists would say they go out there to increase their body temperature, which is true.
• 1:08:16
  Bob: But what they're actually doing is tuning up their electron transport process in the in the mitochondrion.
• 1:08:23
  Bob: That's what they're really doing.
• 1:08:24
  Bob: And we could experiment on this if we could experiment on on lizards, which we can't.
• 1:08:29
  Bob: But you know, you could demonstrate this with biological experiments.
• 1:08:33
  Georg: And this is already reaching complete mainstream with people like Huberman and all these folks like talking about how important it is to receive morning sun.
• 1:08:42
  Georg: And at the same time, I'm I'm just questioning.
• 1:08:45
  Georg: Um I'm still like having these conversations with random people about sunscreen and how they tell me that it's so important to not make your skin age.
• 1:08:54
  Georg: Um I stopped using sunscreen, I think, seven years ago.
• 1:08:56
  Georg: I even had skin cancer like 11 years ago.
• 1:08:59
  Georg: Um and I my my skin is not aging, and what you say is also saying like it helps us to stop aging.
• 1:09:07
  Georg: So how is that?
• 1:09:08
  Georg: How is it possible that people still believe that sunscreen stops their skin from aging?
• 1:09:13
  Georg: And and do you have enough knowledge in these regards?
• 1:09:15
  Georg: Like we don't want to get all of your astrophysics track, but this is this is a very emotive subject.
• 1:09:22
  Bob: Uh Scott Zimmerman.
• 1:09:24
  Georg: I know, yeah.
• 1:09:24
  Bob: Scott you talk to Scott Zimmerman about this because he's worked much more.
• 1:09:28
  Bob: I mean, I I know what the problem is, but I I really don't want to go there because I don't want to make too many enemies.
• 1:09:33
  Bob: But you know, sunscreen, in my view, is essentially useless.
• 1:09:38
  Bob: Yeah, it's doing the wrong things.
• 1:09:39
  Bob: But uh, you know, that's my that's my personal opinion.
• 1:09:42
  Bob: But uh I'd rather talk about the sun.
• 1:09:44
  Georg: We can handle the enemies.
• 1:09:46
  Dave: No, well let's um let let's uh l leave the sunscreen discussion to score.
• 1:09:53
  Bob: Yeah, but I I think this coincidence between the the peak emission, and I had terrible trouble explaining to people, especially lighting engineers, that you know, everybody thinks the sun peaks in the visible, because all the plots you see of sunlight are watts per square meter per nanometer per unit wavelength.
• 1:10:12
  Bob: And they, of course, peak in the visible spectrum and they drop down in the infrared.
• 1:10:17
  Bob: Well, that's well, that's that's true, but you know, the solar spectrum is not a it's not an XY plot, it's a histogram, okay?
• 1:10:26
  Bob: So you bin, you bin something, you bin the energy within a small range of wavelengths, or you bin the energy within you you bin the number the amount of energy within a small range of energy, or you bin the number of photons in a bin at a given energy.
• 1:10:45
  Bob: So there are many ways of representing sunlight, and they don't all look the same.
• 1:10:50
  Bob: And the one that's most appropriate for biophysics, what we're talking about, and also solar panels, the people who work on solar panels, is not to use watts per square meter per nanometer, but to use photon flux, the number of photons per second per square meter per unit area per unit energy.
• 1:11:14
  Bob: And if you actually make that conversion, which I do, and you know, astronomers do this kind of thing all the time, I do, I'm not believed by I'm being accused of, you know, misleading, consciously misleading uh people by distorting the solar spectrum to something which is completely unreal.
• 1:11:36
  Bob: But it's simply a transformation of a histogram, which is a little bit more complicated than transforming a point plot, because you have to take account of the width of the histogram and what you mean by the width of a histogram and so on.
• 1:11:48
  Bob: But anyway, when you re-plot the solar spectrum against a uh a photon number, photon, photon flux against energy, it actually peaks in the near infrared at 1.6 microns.
• 1:12:03
  Bob: And it's rather rather low in the visible where all the photosynthesis happens.
• 1:12:07
  Bob: It's just the photosynthesis photons are much more energetic.
• 1:12:10
  Bob: So we're dealing with 0.7 uh EV photons.
• 1:12:16
  Bob: Photosynthesis synthesis is dealing with you know two and a half EV photons.
• 1:12:20
  Bob: So there's a difference in the photon energy, but the biology is done with photons.
• 1:12:25
  Bob: You know, it's it's done by you know a photon moving an electron or something.
• 1:12:30
  Bob: So so once you once you've reshaped the way you look at the solar spectrum, you can see this peak at 1.6 microns, which is the the energy you need to feed into biology to speed it up, basically to speed it up.
• 1:12:51
  Bob: And make it run better.
• 1:12:54
  Bob: It's it's it's almost like a lubricant.
• 1:12:57
  Bob: It's like it's like squirting oil into the mitochondrion.
• 1:13:00
  Bob: All the infrastructure is there, it can work, it works in complete darkness.
• 1:13:04
  Bob: But in complete darkness, it works very slowly.
• 1:13:07
  Bob: And this is why animals that live in complete darkness they can survive, but they can't do very much.
• 1:13:13
  Bob: And they live a very long time.
• 1:13:14
  Bob: This salamander, that's yeah, I don't know how long it is, but it's a little animal, lives in in caves all its life.
• 1:13:20
  Bob: It lives for a hundred years.
• 1:13:22
  Bob: And something that size should only live for two years or something.
• 1:13:26
  Dave: Was it is in the Greek Greenland shark or something, which it can go up to 400 years old, but in the depths of the ocean.
• 1:13:35
  Bob: Yeah.
• 1:13:35
  Bob: I mean, the the the deviations from these scaling laws are an incredible source of interest because they show you the weird environments, niches in which these animals live.
• 1:13:45
  Bob: So, you know, although it's a very well-defined scaling law, there are deviations from it.
• 1:13:50
  Bob: And the deviating animals are quite interesting.
• 1:13:52
  Bob: The octopus, the bat, uh, the you know, pterosaur, which is one of my favorites, and so on.
• 1:14:00
  Bob: All these things have very peculiar characteristics, uh, but they all fit in this scaling picture because they all have strong deviations for the for their metabolism.
• 1:14:12
  Bob: So, so we've established that you know the sun, because it's the temperature that the sun is, has this atmosphere which is dominated by this H minus ion, which uh causes this excess energy.
• 1:14:27
  Bob: The peak would still be at around the same wavelength, even without the H minus ion.
• 1:14:31
  Bob: But the H minus ion means you get maybe 20% more energy at these wavelengths than you would otherwise.
• 1:14:38
  Bob: And it's interesting the way life seems to have honed in, honed in on this on this excess energy uh to make everything as optimum as you possibly can.
• 1:14:48
  Bob: So I think that's a that's the I think that's an important conclusion.
• 1:14:56
  Dave: I mean, I I think it's something that changes the landscape.
• 1:14:58
  Dave: It's really interesting.
• 1:15:00
  Dave: I I had a question about you, you know, so we we as we're being hit by photons the whole time, different and they that there's different wavelengths.
• 1:15:11
  Dave: So are we are we as well as photons from the sun, are we being hit by photons from other stars?
• 1:15:18
  Dave: And the you know, just I I was just kind of curious about what's what what our bodies are are are being sort of bombarded with on a daily basis.
• 1:15:30
  Bob: Yeah, they are I mean, they're a very broad spectrum, yes, and not all exactly sun-like spectrum.
• 1:15:36
  Bob: So yeah, but that's okay.
• 1:15:38
  Bob: I mean, the sun is by far the brightest source we see, so that's where all the energy transfer happens.
• 1:15:43
  Bob: Right.
• 1:15:44
  Bob: Um but the other, you know, other photons can trigger different things.
• 1:15:48
  Bob: And I I think there are other things I could tell you, but an eggshell, uh a hen's eggshell is, you know, can be brown, okay?
• 1:15:58
  Bob: You know that.
• 1:16:00
  Bob: And uh and it's actually not brown, it's it's flecks of purple, which make it look brown.
• 1:16:06
  Bob: If you look at it with a magnifying glass, you'll find it's flecks of purple.
• 1:16:10
  Bob: And that purple is is uh uh a molecule called pr uh protoporphyrin 9.
• 1:16:16
  Bob: And it's the precursor molecule to the synthesis of both hemoglobin and chlorophyll.
• 1:16:21
  Bob: In chlorophyll, you add magnesium to the porfyrin ring, and in in in hemoglobin you add iron to the porfyrin ring.
• 1:16:29
  Bob: But this protoporphyrin 9 is a very photoactive substance, and it's used in photorine, well, it's not used directly, but it's it it its type of thing is used in photodynamic therapy for killing cancer tumors using using red light.
• 1:16:46
  Bob: Blue light originally.
• 1:16:48
  Bob: Um and it's a very photoactive substance.
• 1:16:52
  Bob: It's responsible for some types of porphyria.
• 1:16:54
  Bob: I think King George, the mad King George III.
• 1:16:56
  Bob: Oh, yeah, yeah, yeah.
• 1:16:57
  Dave: The blue thing.
• 1:16:59
  Bob: Suffered, yeah, suffered porphyry.
• 1:17:01
  Bob: And uh it's this protoporphyrin 9, which is uh uh I say it's very chemically active.
• 1:17:08
  Bob: And it can actually be transformed by light into uh into something which is much more like chlorophyll, a called a chlorine.
• 1:17:15
  Bob: It's very closely related to a porphyrin, but it's called a chlorine.
• 1:17:19
  Bob: But that absorbs at the same wavelength as chlorophyll.
• 1:17:22
  Bob: But anyway, that the the hen deposits this protoporphyrin on the on the egg as the egg passes through the oviduct.
• 1:17:31
  Bob: It sort of inject sprays it onto the onto the egg.
• 1:17:36
  Bob: And people have wondered for a long time why why would why would a hen do that?
• 1:17:41
  Bob: There's a beautiful paper by a Japanese group on about 10 years ago now where they said actually this protoporphyrin is is so biologically active that it acts as a um an antibacterial on the on the shell of the egg.
• 1:17:56
  Bob: This is why you can keep eggs for ages and they don't get infected.
• 1:17:59
  Bob: Because this protoporin will kill most bacteria.
• 1:18:04
  Dave: Wow.
• 1:18:04
  Bob: In the way that it killed King George III.
• 1:18:07
  Bob: And so the the birds, not only the hen's egg, but the birds are using um using this uh this chemical as an anti-antibacterial coat.
• 1:18:19
  Bob: And in in other ways, and we've Scott and I have been discussing this for a long while now, if you look at the production of reactive oxygens in the body, which we know are damaging to life, but also important signalers in light, you can generate reactive oxygens by shining light on the skin.
• 1:18:38
  Bob: The skin is like a solar panel, and uh it will generate reactive oxygens.
• 1:18:43
  Bob: And uh, you know, most of these reactive oxygens live a very short time before they decay.
• 1:18:50
  Bob: Uh, but there are things like hydrogen peroxide, which live for longer and can be derived from these reactive oxygens.
• 1:18:57
  Bob: And we think that the the skin and sunlight is acting as an anti as a barrier against uh pathogens.
• 1:19:06
  Bob: So, you know, we know that essentially nobody caught COVID outdoors.
• 1:19:12
  Bob: They will caught COVID indoors.
• 1:19:14
  Bob: When you're outside in the sunlight, your skin is generating an anti an anti-pathogen coating on it because of the sunlight, which will increase the protection against uh uh viruses and so on.
• 1:19:29
  Bob: So, you know, there there are many photons out there that are doing things which we don't yet fully understand.
• 1:19:34
  Bob: You know, that when we get once once I once I go beyond two and a half microns, I have spectrometers which can measure up to two and a half microns.
• 1:19:42
  Bob: Once I go beyond two and a half microns, I'm blind, so I can't look for myself about what's going on.
• 1:19:47
  Bob: And it's also very hard to get cameras that work above two and a half microns.
• 1:19:51
  Bob: They're becoming available now, but they're extremely expensive, and I can't afford them.
• 1:19:55
  Bob: So if we could look at life, you know, between two and four or five microns with cameras and spectrometers in vivo, I mean in in real life, I think we'd learn a lot more.
• 1:20:10
  Bob: So this is this is something we need to, we need technology to do better.
• 1:20:14
  Bob: I think we'd learn a lot about the way the sunlight is interacting at longer wavelengths.
• 1:20:20
  Bob: When you go far enough into the infrared, you get to the stage where you're you're you're you're getting most of your photons from the thermal energy in your body from your 37 degrees.
• 1:20:31
  Bob: And so uh light, then you ought to get rid of light, you don't want to absorb it.
• 1:20:35
  Bob: But up until those wavelengths, I think the light is doing many things in our body uh that we don't yet fully understand.
• 1:20:41
  Bob: And some of it may to do, maybe to do with reactive oxygen generation and other things like that.
• 1:20:48
  Bob: So this is why we need the full solar spectrum getting back to the sun.
• 1:20:51
  Bob: It's very important to us.
• 1:20:54
  Bob: And by cutting this off in the in in the indoors environment, we you know we are you look at the rate of type 2 diabetes and obesity now, it's huge.
• 1:21:06
  Bob: It's huge.
• 1:21:08
  Georg: I I was thinking, you know, like Bob, you mentioned um windows filtering out everything but uh the visible light spectrum.
• 1:21:14
  Georg: Yeah, and and now we learn like week after week we get in contact with like really interesting scientists, and they all basically agree with what you say.
• 1:21:23
  Georg: And I'm like, like, why don't we have windows that um let all the spectrum through?
• 1:21:29
  Georg: And I was on on X, I saw a post by a guy, and he was mentioning that he found eventually he found a producer of window glass which transmits all the light spectrum, and this company is focused on animal shelters because they want to allow these animals to have like a good, healthy life.
• 1:21:50
  Georg: I think that's so funny, you know.
• 1:21:51
  Georg: Like who cares about humans?
• 1:21:55
  Bob: This is a hangout of it from the fact from the from the time when we thought humans were different from animals, yeah.
• 1:22:02
  Dave: I I think it's I think it's it it's it's fascinating.
• 1:22:06
  Dave: I mean, I guess you know, I was gonna suggest we kind of conclude this bit of the podcast, but uh you you know, in summary, like the life we're we're intrinsically part of the solar system in terms of the way, but it is also we're not just intrinsically part, we're we're literally the product of the big ban, you know.
• 1:22:30
  Dave: This you can follow our our history back to that which I I think is is really amazing and not something that I'd kind of particularly thought about until I saw your presentation.
• 1:22:44
  Dave: I think what's also really interesting is how little we know about the impact of light on our bodies, and it sort of feels like and life.
• 1:22:53
  Dave: I mean, I go go I should say more broadly on life.
• 1:22:57
  Dave: I think it's a very it's very interesting, and you know, now's not the time to discuss biophotons and things like but you you know the whole subject of light i is just is just illuminating, isn't it?
• 1:23:14
  Dave: So um, so I and so I really appreciate you going into the detail around the universe, the sun, life, the the the scaling.
• 1:23:25
  Dave: I mean the scaling thing, you know, that that's new to me this week, I guess.
• 1:23:29
  Dave: But I really got to think about because that that that to me sort of makes it sound like the there's an inevitability about life based on you know what what's kind of gone on.
• 1:23:44
  Dave: Um I I I think I wanted to turn now to another topic, which is in your presentation, I'm just gonna mute this slightly so I will edit this bit out.
• 1:23:56
  Dave: Yeah, sorry.
• 1:24:01
  Dave: Um in the presentation, you and you know, we've talked about it already.
• 1:24:07
  Dave: We you were kind of hinting at this can the the this not connection, but how the origins of stars and you know the the life cycle of stars is very similar to life.
• 1:24:21
  Dave: And you know, I wondered if we could just talk about that because you know, life is defined by certain things like uh metabolism and you know, a start point, metabolism, and then an end point, which you you know it sounds very similar to as you were sort of saying in your presentation, to start.
• 1:24:42
  Dave: So anyway, I wondered if you could just talk about that in a bit more detail in terms of the the to the way you're sort of thinking about that.
• 1:24:51
  Bob: Yes, I mean this is I I say I've only been thinking about this for a reasonably short time, and this is this is that time is when all these jigs and jigsaw pieces started fitting together very quickly.
• 1:25:02
  Bob: So I I was sort of bowled over by by this process.
• 1:25:06
  Bob: But, you know, I I say I'm not I'm certainly not the first person to point out that that similarity uh between life and stars.
• 1:25:16
  Bob: In fact, uh, you know, there is some literature, not very much literature about this, but actually part of the literature is uh produced by somebody I actually knew quite well in my in my astronomical career.
• 1:25:27
  Bob: He was at the Space Telescope Science Institute.
• 1:25:30
  Bob: And so there is, there is, there are discussions around around this point.
• 1:25:34
  Bob: Um but I don't think they've delved very deeply into the biological uh implications of this.
• 1:25:42
  Bob: But I think there's something.
• 1:25:45
  Bob: If I go right back to um to Stephen Hawking's ideas, I mean he um in the later years of his life, he was very much concerned with you know the cosmology and the early universe and black holes and so on.
• 1:26:01
  Bob: And there is there is a book that um was written by his student who worked with him for the last 20 years of his life called uh Thomas Hertog, called The Origin of Tie.
• 1:26:13
  Bob: Uh it's a it's a mind-blowing book, I must say.
• 1:26:17
  Bob: And the question he addresses is the whole question of the origin of the physical laws very, very early in the universe.
• 1:26:28
  Bob: And um the idea that he seemed to be pondering was the fact that you know, all the string theorists who are trying to calculate the uh the values of the um physical constants and understand any everything from the first mathematical principles.
• 1:26:46
  Bob: So, Hawking was hinting that it didn't actually work in that way.
• 1:26:50
  Bob: It worked by a process which was much closer to Darwin's ideas, in that you know, in the very, very early universe, you know, the first 10 to the minus 31 seconds or something, um, there was lots and lots of energy density, and uh, and there weren't actually any physical laws then, because you know, everything was such high temperature, such high density.
• 1:27:13
  Bob: Uh, and the physical laws started to emerge uh as uh as the universe evolved.
• 1:27:19
  Bob: I'm not sure I'm explaining this to everyone.
• 1:27:20
  Dave: No, no, you you you're you're very it's it's good so far.
• 1:27:24
  Bob: Apologies.
• 1:27:25
  Bob: Apologies to uh to Stephen Hawking, whom I knew, of course, vaguely, not very well, but um there was a there was a process where certain parts of the universe evolved more quickly into complexity than others.
• 1:27:43
  Bob: I think this is the idea he was getting at.
• 1:27:45
  Bob: So there was a kind of natural selection process in the in the very early universe where the physical certain kinds of physical law dominated the evolution and eventually took over.
• 1:27:59
  Bob: So it's a essentially a Darwinian process of selecting the most effective kinds of physical behavior, called it a physical law, it hasn't become physical law, but the physical behavior of the Mishmah.
• 1:28:14
  Dave: So what you're saying is there could have been potentially other laws which just display.
• 1:28:18
  Bob: Yes, and and and the new the the physical constants were frozen in at this point.
• 1:28:23
  Bob: But you know, they're frozen in essentially at random because of the, you know, this it's an evolutionary process rather than a mathematically driven process.
• 1:28:34
  Bob: And um I think that means the the the you know the corollary of this is that the universe we've ended up in is a universe which is good at producing complexity.
• 1:28:46
  Bob: If we weren't in a unit, if if our universe didn't produce complexity, we wouldn't be here.
• 1:28:52
  Bob: So it's an anthropic thing in a way.
• 1:28:55
  Bob: But uh reminds me.
• 1:28:58
  Georg: So Max, do you know Max Max Tagmark?
• 1:29:01
  Georg: Yeah, yeah, and I guess and then in his book, our mathematical universe he describes basically how from some quantum fluctuation initial structure, yeah, an infinite amount of parallel universes was created, and we are just residing in the single one that has like all these super foundational physical constants calibrated in a way that life is even possible, and all the other universes either collapsed or blew up into nothing.
• 1:29:28
  Bob: And yeah, you got the idea.
• 1:29:32
  Georg: Explains a lot.
• 1:29:33
  Bob: But the implications of this, of course, is you know, we're we're the universe is pregnant with complexity, and so it's you know it's doing it as best it can.
• 1:29:43
  Bob: And we we're we we're only bright enough to see two kinds one is the formation of stars and the periodic table, and the other is the formation of life, and we haven't got further yet.
• 1:29:56
  Bob: I mean, if I talk to ChatGP GPT, it'll Say, well, I'm the next step.
• 1:30:02
  Georg: Very confident.
• 1:30:05
  Bob: But you know, you see what I mean.
• 1:30:07
  Bob: So there is a somehow we're living in a in a universe which wants this complexity.
• 1:30:12
  Bob: And that means that the physics we deal with in all these interesting things is very much non-equilibrium physics.
• 1:30:20
  Bob: You know, the equilibrium physics of Newtonian science and so on is great.
• 1:30:24
  Bob: It gave us a good foundation.
• 1:30:26
  Bob: But the physics of the real world that we're living in now is a universe which is far from thermodynamic equilibrium.
• 1:30:33
  Bob: And it's much more like thermodynamics, the language of thermodynamics, than the language of Newton.
• 1:30:40
  Bob: And yeah, there are other people who are talking about this or written books about it.
• 1:30:47
  Bob: But I think this is this is the kind of picture that I have, is that, you know, complexity is there, built in, waiting to have.
• 1:30:56
  Bob: We just have to generate the conditions.
• 1:30:58
  Bob: And the conditions are very, very simple.
• 1:31:00
  Bob: And I think, you know, as I as I ended my talk on the last slide, I said, well, you know, Schrdinger would have said, life is sunlight, stardust, and a cold space.
• 1:31:18
  Georg: Sounds very romantic.
• 1:31:20
  Bob: Um but but that's it.
• 1:31:23
  Bob: You know, that's that's it.
• 1:31:24
  Bob: You know, all the rest is a all the rest is a detail in between.
• 1:31:31
  Georg: And I'm I'm taking a little departure here now.
• 1:31:33
  Georg: Like, what is this whole thing about?
• 1:31:36
  Georg: Like, do you ever think about it?
• 1:31:37
  Georg: And and for me, this always goes towards consciousness, because that's the most fundamental I don't know, mechanism I can think of.
• 1:31:46
  Georg: And also like when when you describe how how a star is working and how a star is maintaining its own entropy, I think maybe that's even like a biological or physical fact.
• 1:31:56
  Georg: I'm not uh I'm not an expert, but for me it sounds like any any any organism or structure that somehow maintains entropy is like alive, basically.
• 1:32:05
  Bob: And I I mean I I I didn't say this.
• 1:32:08
  Bob: I mean I thought this, of course.
• 1:32:09
  Bob: I thought the stars alive, you know, it's obvious to me, but I'm not sure I have the courage to say it online.
• 1:32:15
  Georg: But but but what what every what what is not alive?
• 1:32:18
  Georg: I mean, isn't for me, I've reached a point in life where I say all matter is conscious.
• 1:32:23
  Georg: It's just the question on whether we are able to to realize the consciousness of all matter because some structures are just very simple.
• 1:32:30
  Georg: Like there's Alan Watts, this famous philosopher, and he says, like a gong, you know, like a gong where you hit on it.
• 1:32:36
  Georg: And like the consciousness of a gong is quite simple.
• 1:32:40
  Georg: It gets struck by another physical structure, then it's it starts to vibrate amidst the frequency, and that's basically the consciousness of the gong.
• 1:32:48
  Georg: And and all matter is somehow that consciousness, and some some some organisms are more complex, like a star as you described this seem seems quite elaborate, actually.
• 1:32:57
  Georg: Um, yeah, maybe maybe you want to touch this topic a little bit because I'm really, really curious about it.
• 1:33:02
  Georg: And also given the massive knowledge you have, like what is your stance on?
• 1:33:07
  Bob: Well, I I think I what I've learned, I'm I'm very pragmatic in what I've learned.
• 1:33:11
  Bob: And uh, I think you know, it's it's well known and well understood that in order to get things to happen, you have to have energy and you have to have a gradient.
• 1:33:22
  Bob: And I think uh, you know, you naturally in life and in the star, you get a a strong entropy gradient because you have high entropy uh low entropy in the center and high entropy outside, and there's a strong gradient.
• 1:33:37
  Georg: That means like the the the distribute like the amount of entropy along some axis that's the gradient.
• 1:33:42
  Bob: Yeah, and you know, you generate entropy by using, utilizing energy, you're dissipating energy in the structure and you're generating entropy.
• 1:33:51
  Bob: And so you, you know, the the presence of the energy allows you to generate a gradient of entropy.
• 1:33:59
  Bob: And the gradient of entropy is where things are actually happening.
• 1:34:02
  Bob: So if you're looking around yourself, you know, you need to look for a gradient of entropy in order to locate those places where interesting things are going to happen, I think.
• 1:34:15
  Dave: No, it's it I mean it what one thing I just wanted to turn back to complexity as well, because I I had a chat with Ulysses Dormo, which was fascinating, because we he was we we ended up just talking about like and this goes to ultra-processed food and and and kind of the we live in a world where convenience is like I think that's the overriding kind of human ambition is convenience.
• 1:34:50
  Dave: And you know, I I did a degree in psychology many years ago, and um I remember my cognitive lecturer talking about the la the brain being a very lazy organ.
• 1:35:02
  Dave: Not that it's lazy it's basically looking for the line of least resistance, and and it kind of makes me wonder if convenience and the upshot of convenience has never been particularly good, actually.
• 1:35:18
  Dave: Um, but it's sort of almost kicking back against the overriding uh premise of the universe in terms of that point around complexity.
• 1:35:28
  Dave: So look, I I don't this isn't a fully I thought formed idea in my head, but it's sort of I I think convenience means you know, LED lights are convenience, processed food a convenience, like transport is convenient.
• 1:35:45
  Dave: All of these things have made our lives better, and yet maybe not at the end of the day.
• 1:35:50
  Bob: Well, there's a word for this.
• 1:35:52
  Bob: It's called hormesis.
• 1:35:53
  Bob: And you should talk to Alastair Nunn, who was on the talk.
• 1:35:57
  Bob: He's he's the science director of the Guy Foundation.
• 1:36:00
  Bob: Right, right, right.
• 1:36:01
  Bob: Uh talk to him about hormesis.
• 1:36:04
  Bob: You have to str you have to stress yourself in order to remain healthy.
• 1:36:08
  Bob: Uh you know, you you you give yourself sm small doses of of of stress, like uh, you know, toxic chemicals and and so on.
• 1:36:17
  Bob: You need to you need to get your body to react to um difficulties and and build and build the complex it forces you to build the complexity, I think.
• 1:36:29
  Dave: Which is which is really like I I I go back to like the that that whole notion of stars, uh like what's going on there, and again, there's an order of things which if we it it philosophically, if we don't sort of align ourselves to that order of things, then you know, I things just probably won't work out well.
• 1:36:54
  Dave: So yeah, I mean it's really, really interesting and eye-opening like thinking all of this stuff through.
• 1:37:00
  Dave: I mean, and ultimately, like I it the the sort of most basic thing for us, like I I guess coming out of this is is re-articulating the fact that like we really do have this intimate connection with sunlight and the sun.
• 1:37:21
  Dave: And if we break that, then it's not going to end well for us, you know, as individuals or or or as a species.
• 1:37:31
  Dave: And y you know, there's certain things we can do about going outside and you know, spending time uh under trees and you know, eating kind of like fresh fruit and all of these things which which help align us back to the natural order of things.
• 1:37:50
  Dave: And you you know, again, what we're doing with Shadow Map is is providing a tool so people can kind of find their place in the sun much more easily.
• 1:38:01
  Dave: And you know, I think what's great is to have like all of this backed by sort of deep science, you know, and and as you you've managed to bridge the divide between astrophysics and biology, and I think it it's so interesting that kind of that that's happened.
• 1:38:24
  Dave: Um so yeah, look, I I I I I wonder if you've got sort of anything else that you wanted to add.
• 1:38:31
  Dave: Um we I'm very, very conscious of time because we're over an hour and a half so far.
• 1:38:36
  Bob: Yes, yes.
• 1:38:37
  Bob: Well, this was that was inevitable, I think.
• 1:38:39
  Bob: Yeah, no, I think I think the main the main point I wanted to get over was the the breadth of this topic, you know, the the whole cosmology of it, which it needs to be thought of as a cosmological issue, I think.
• 1:38:51
  Bob: And that results in the ubiquity of the conclusions that we draw.
• 1:38:55
  Bob: In fact, you know, it applies to the whole universe, I think.
• 1:38:58
  Bob: Physics is the same everywhere.
• 1:39:01
  Bob: And um I think the other thing I I mean I'll I'll I'll end on this point, but and I've used a number of aphorisms in my talk, which you can extract, but you know, life is an antenna with receivers tuned to sunlight.
• 1:39:16
  Dave: Which I I I love that by the way.
• 1:39:18
  Dave: I mean, you should be a marketing.
• 1:39:20
  Dave: So, you know, the other the other thing you said about uh sorry, I've got to find the quote, and I'm gonna put my glasses on.
• 1:39:28
  Dave: Um so you you must sort of go into then the antennae.
• 1:39:33
  Dave: Um but you talked about sorry, I'm gonna find it.
• 1:39:39
  Dave: Um what was it?
• 1:39:44
  Dave: The we life is uh where is it?
• 1:39:51
  Bob: It was the one in the beginning, about the shadow.
• 1:39:53
  Bob: Yeah, yeah, yeah.
• 1:39:54
  Bob: Yeah.
• 1:39:55
  Bob: Life thrives on the light that's used to form its shadow.
• 1:40:01
  Georg: I think that's that's deep.
• 1:40:03
  Georg: It is.
• 1:40:06
  Bob: It is deep, I think, yes.
• 1:40:07
  Dave: And then the other thing about the antennae, which I mean again, can you sort of just give us that quote as well?
• 1:40:14
  Bob: Because I think Yeah, I mean the the the the quote is, and I I changed it from sunlight to starlight, but actually, uh, you know like light is uh life is an antenna tuned with receivers tuned to starlight and a radiator tuned to the cold of outer space.
• 1:40:36
  Georg: That's so profound.
• 1:40:38
  Georg: Like I'm I mean, like you you you state these, like you say these um these quotes and and we just keep on talking, but I think we could just um introduce a minute of silence so that people let people think of the implications.
• 1:40:53
  Bob: Yeah, yeah, yeah.
• 1:40:53
  Bob: Yeah, but I mean I I if you want me to end, I'll end on the the the th the thing about the the shadow, uh the plot that I showed almost right at the end, and I have the original plot I sketched in a notebook when I was on holiday a few just a few weeks ago, which has this for historical purposes.
• 1:41:11
  Bob: When I took the uh the metabolic theory scaling law for a fruit fly and a human and plotted the the basic the basal metabolic rate from the from the literature for a fly and a and the human on the scaling law plot, it had exactly the slope of three-quarters as as Western people say.
• 1:41:32
  Bob: And then I thought I did the experiment, I just measure the cross-sectional area of a fruit fly, i.e.
• 1:41:38
  Bob: the area that would absorb sunlight if it was out in the sun, and do the same for a human.
• 1:41:43
  Bob: And I I know how much radiation I'm getting from the sun within that area, in in this metabolically active range of around three-quarters of an electron volt, and I would just plot those two points on the same diagram, watts against mass uh against um uh uh um mass.
• 1:42:04
  Bob: And I did that for a fruit fly and a human.
• 1:42:07
  Bob: And I I I literally had no idea where those would would fall on the map.
• 1:42:11
  Bob: And they they fell on they fell.
• 1:42:16
  Bob: Just to remind you, I'll show you in my notebook.
• 1:42:21
  Bob: They fell on that on that line there.
• 1:42:28
  Speaker 2: Okay.
• 1:42:29
  Bob: The the yellow one is the is the sunlight, and the green one is the uh is the basal metabolic rate.
• 1:42:35
  Bob: So essentially exactly parallel, uh, but a factor of five above.
• 1:42:40
  Bob: Now that means you've from sunlight, you have something like a factor of five of your basal metabolic rate available to you to spend by bringing photons into your body to allow you to thrive.
• 1:42:56
  Bob: Now you're not going to absorb all those photons, and you're certainly not going to absorb all of them in the right place, but there are there's quite a pool of photons there.
• 1:43:03
  Bob: So that that just that one plot with two points on it convinced me that sunlight was absolutely crucial for metabolism.
• 1:43:16
  Dave: Amazing, amazing.
• 1:43:18
  Dave: Well, thank you so much for joining us.
• 1:43:20
  Dave: I mean, I'm I like there's so much in there uh which I need to kind of go away, think about, and ponder.
• 1:43:27
  Dave: Um and uh yeah, I I think uh, you know, the we'll put a link into the Jeffrey West book.
• 1:43:37
  Dave: Um, and it's certainly one of the ones that I'll be ordering soon.
• 1:43:42
  Dave: Uh by the way, I'm trying to make my way through Quantum Biology by uh the guy, uh Jeffrey Guy, which I find fascinating.
• 1:43:49
  Dave: But it's uh it's uh I I I actually tried Nick Lane's um uh his book as well, but that was beyond me.
• 1:43:58
  Bob: I think Jeffrey's I've read all I've read all Nick Lane's books.
• 1:44:01
  Bob: I haven't read Jeffrey Guy's book, don't tell him, I haven't read his book yet.
• 1:44:06
  Dave: But but no, look, I I there's so much there, and I'm sure we'll definitely be coming back to you over the I think it's I think it's wise not to go on too long now because you know podcasts can be too long.
• 1:44:18
  Georg: So uh long podcasts.
• 1:44:20
  Georg: I'm a huge fan.
• 1:44:22
  Bob: That's okay.
• 1:44:23
  Speaker 2: People always complain.
• 1:44:24
  Speaker 2: People complain about it.
• 1:44:28
  Dave: Thank thank you.
• 1:44:29
  Dave: Okay.
• 1:44:31
  Georg: One thing I would like before we end is um Bob, if you if you had one, I mean, like one main takeaway for me was that everybody basically should learn astrophysics.
• 1:44:40
  Georg: Like it doesn't matter what they prefer.
• 1:44:41
  Georg: Right?
• 1:44:43
  Georg: Do you agree?
• 1:44:44
  Bob: No, uh no, I'm not I'm not saying that.
• 1:44:46
  Bob: But I think uh, well, some years ago, um somebody called David Christian uh in in Britain proposed the idea of teaching in schools, you know, not the birth dates of all the all the kinks of the year dot, but actually teach them big history.
• 1:45:03
  Bob: And uh this is a history of the universe from the beginning right through to modern politics, but all in one subject.
• 1:45:11
  Bob: And uh he uh had the opportunity of explaining this idea to Bill Gates, and Bill Gates thought this was a great idea and funded the Big History Project.
• 1:45:20
  Bob: Look up the Big History Project on Google, and you'll find there's a huge amount of very high quality material for schools in there.
• 1:45:29
  Bob: And it really took off in Australia and the US, but never in Britain, I don't think.
• 1:45:34
  Georg: Interesting.
• 1:45:35
  Georg: My image for Bill Gates just recovered a little bit.
• 1:45:39
  Bob: Well, yes, I mean it was uh it's it's it's terrific.
• 1:45:42
  Bob: And uh I've I've taught this to kids here here in Bath on occasions, and you know, they they lack this stuff up.
• 1:45:52
  Georg: If if you would um like share one thing that you would love our our audience to hear, like is there like one main message you want to share?
• 1:46:02
  Georg: I'm just very curious.
• 1:46:05
  Bob: Well, I think it's uh getting outside is gonna be very beneficial.
• 1:46:12
  Bob: I think that's what all of us would say.
• 1:46:14
  Bob: Glenn would say, Roger Schwelt would say, Scott would say, you know, we need to fix the buildings, but that's a technical problem, and it's not expensive.
• 1:46:23
  Bob: Well, the glass is the glass is a problem because if you use ordinary glass, you're gonna fry inside a skyscraper.
• 1:46:30
  Bob: That's the problem.
• 1:46:31
  Bob: There are there are engineering problems that have to be solved for doing that.
• 1:46:34
  Bob: But changing the lighting is trivial.
• 1:46:37
  Bob: Well, it's not trivial, but it you can do it for nothing.
• 1:46:40
  Bob: I mean, people ask me how much should I pay for therapeutic lamps?
• 1:46:44
  Bob: And I say, uh between nine and ten pounds.
• 1:46:48
  Bob: And that's that's you getting it getting an an oven, you know, 40 watt oven lamp that you know you can still get tungsten filament lamps that go in your oven because you can't put LEDs in an oven.
• 1:46:57
  Bob: Yeah.
• 1:46:58
  Bob: And uh put that, screw that into a little um uh um angle poised lamp.
• 1:47:03
  Bob: Yeah, no.
• 1:47:04
  Bob: And run it with a dimmer, run it at a lower voltage, because then the filament will last forever.
• 1:47:09
  Bob: And you don't need it, right?
• 1:47:10
  Bob: You don't need it at full voltage.
• 1:47:12
  Bob: So it's it costs about 10 pounds.
• 1:47:14
  Dave: It's amazing.
• 1:47:15
  Dave: Great.
• 1:47:15
  Dave: I mean, look, it's it's the brilliant thing about this is you know, there's that there's spokespeople like yourself and Glenn and Scott and Roger.
• 1:47:27
  Dave: Everybody seems to be very willing to share for nothing the advice that they have.
• 1:47:35
  Dave: And then the cost of actually you know reconnecting yourself with with sunlight is i is virtually nothing as well, you know.
• 1:47:43
  Dave: So um, you know, I think it's it's brilliant.
• 1:47:46
  Dave: But thank you so much again.
• 1:47:47
  Georg: Thank you, Bob.
• 1:47:48
  Bob: What what I just uh what I just will say, my my final word is that the only reason we're doing this, of course, is that we screwed up the lighting uh 20 years ago with the with the LEDs.
• 1:47:59
  Bob: We didn't think.
• 1:48:00
  Bob: We didn't think.
• 1:48:01
  Bob: If we if we hadn't if if we hadn't uh done the LED thing, we wouldn't be discussing this now, because it wouldn't be necessary.
• 1:48:11
  Bob: Because there wouldn't be obese people, there wouldn't be uh people with diabetes and so on.
• 1:48:15
  Bob: That's my message.
• 1:48:18
  Dave: Well, so can I sort just to so you fundamentally believe that?
• 1:48:23
  Bob: I mean I I I I there are many other contributors to these diseases.
• 1:48:27
  Bob: I'm not saying it's everything.
• 1:48:28
  Bob: I think the ultra-processed food is is very important, but the ultra-processed food business is very closely related to what I'm saying.
• 1:48:35
  Bob: It's all to do with entropy.
• 1:48:37
  Bob: Yeah.
• 1:48:37
  Bob: No, no, I don't it's the fact that, you know, the the ultra-processed food doesn't contain it doesn't contain nutrients.
• 1:48:45
  Bob: It doesn't contain proper nutrients.
• 1:48:47
  Bob: You can get fat on it, but you can't thrive on it.
• 1:48:52
  Dave: No, I think that's that's the huge difference.
• 1:48:55
  Speaker 2: Yeah.
• 1:48:56
  Dave: Fantastic.
• 1:48:56
  Dave: Okay, well listen, we shall leave it there.
• 1:48:59
  Dave: But um it's a subject we'll probably come back to with you time and time again.
• 1:49:06
  Bob: I'll try and stay alive long enough.
• 1:49:08
  Dave: Thank you very much.
• 1:49:09
  Dave: Please do get out in the sun, Bob.
• 1:49:11
  Bob: So uh Okay, all the best.
• 1:49:14
  Bob: Pleasure to talk to you.
• 1:49:15
  Bob: Okay, cheers.
• 1:49:17
  Dave: Thanks for listening to Sunlight Matters, brought to you by Shadow Map, where we explore how sunlight influences the way we build, design, and live each day.
• 1:49:27
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• 1:49:34
  Dave: You can also search Sunlight Matters on Google to find all our episodes, guest information and resources about sunlight analysis, solar exposure, and the best home orientation for natural light.
• 1:49:47
  Dave: You can also head over to shadowmap.org where you can download our iOS app for free today to visualize how sun is currently impacting your life.
• 1:49:58
  Dave: We appreciate you being part of the conversation, and we'll see you next time, where you can keep exploring the world through the lens of light.