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2022-11-23: How To See Black Holes By Catching Neutrinos

  • 13:02: ... hide your IP address and encrypt your internet data so that your digital life is shielded from ISPs, network administrators and others you don’t want ...
  • 15:22: In other words, fewer than 1 in a million people see a neutrino once in their life.

2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table?

  • 13:25: ... of 184 for neutrons, and 126 for protons, and they could have half lives of millions of ...
  • 14:33: For instance, Technetium is used all the time in medical imaging as a contrast agent, and in this case its short half life is actually an asset.
  • 14:43: ... using an isotope with a half life of only six hours we can greatly reduce the amount of radiation the ...
  • 15:18: Americium is critical for smoke detectors - so it’s an artificial element that has saved many lives.
  • 18:57: ... Cleveland points out that life may have had the potential to arise many times on early, except for the ...
  • 19:20: Indeed we see that the DNA off all life clearly came from a single common ancestor.
  • 20:20: Just like life on earth probably did.

2022-11-09: What If Humanity Is Among The First Spacefaring Civilizations?

  • 00:59: We see no evidence of other life out there.
  • 01:02: Which may mean that humanity is super early in the history of life in the universe.
  • 01:39: If life can appear for trillions of years, then it’s suspicious that we find ourselves in the first billions.
  • 02:14: Maybe the future history of the universe isn’t as hospitable to life after all.
  • 02:26: ... to say something about the earliness of humanity and the future of life just based on our arrival date and the apparent emptiness of the ...
  • 03:07: They try to answer it building a simple model of the emergence and spread of intelligent life in our universe.
  • 04:50: Once a habitable star along with its habitable planets have formed, life needs time to evolve.
  • 05:12: To get from primordial goop to intelligent life you need a sequence of fluke events.
  • 05:44: The number of hard steps is a big deciding factor in how fast the universe can spawn intelligent life.
  • 06:00: ... the number of hard steps it typically takes to produce intelligent life, like ...
  • 06:37: ... lets us write down a mathematical function for the appearance rate of life that depends on a simple parameter - the number of hard ...
  • 08:00: If it’s possible for life to evolve on these planets, then new civilisations could continue to emerge for trillions of years into the future.
  • 08:16: Since they’re very dim, orbiting planets need to be very close to the star in order to have liquid water, which may be necessary for life.
  • 08:33: The authors of this paper argue that life could well evolve on red dwarf planets.
  • 08:39: After all, why should all life have the same requirements as Earth life?
  • 08:49: So there are two main deciding factors of our birth rank: the number of hard steps and the maximum lifetime of habitable planets.
  • 09:08: Each point represents a choice of hard-step-number and maximum planet lifetime, and the color of that point tells you our birth rank.
  • 09:38: If red dwarfs are habitable but it’s easy for life to evolve, we’re in something like the first 0.1% or even first thousandth of civilisations.
  • 10:37: ... that will happen one day in the future that prevents any new intelligent life from ...
  • 11:11: No new life has the chance to evolve, because every planet is already occupied by space-fairing advanced life.
  • 11:36: When we look at life on Earth, it seems that life has a common tendency to aggressively expand into new territories and niches.
  • 13:34: ... and spread through the universe, ending with a universe totally full of life. ...
  • 16:29: ... humanity is early and this universe has countless trillions of years of life and civilization ahead of ...

2022-10-26: Why Did Quantum Entanglement Win the Nobel Prize in Physics?

  • 11:55: It can rule out that the secret information about the entangled particle states lives in the particles themselves - that’s what local means here.
  • 15:08: Alek passed away at a young age, but by all accounts was a true scientist his entire life.

2022-10-12: The REAL Possibility of Mapping Alien Planets!

  • 00:33: ... terms   of size and mass. Of course if we want to  find life or actually visit these planets   it’d be nice to know a bit ...
  • 12:52: ... and tidal and changes, and even changes due to the activity of life. Every exoplanet that we want to image requires a new fleet. That ...
  • 14:06: ... how that goes.   But it’s crazy to imagine that within our lifetimes we may have mapped in detail   the surfaces of distant worlds, ...

2022-09-28: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?

  • 00:57: ... constant?” Even Richard Feyman pondered its mysteries his entire life. ...
  • 08:22: ... different, carbon would never have formed  inside stars, making life ...
  • 08:49: ... that they landed on just the right values to allow for the formation of life - unless of course there are many, many universes with different values ...

2022-09-21: Science of the James Webb Telescope Explained!

  • 04:40: ... IR sensitivity allows it to see the cool dust and gas that lives between the stars, as well as peer through that dust which normally ...
  • 05:09: ... in other solar systems, which is an important step towards finding other life out there in the ...
  • 05:57: Most of what the telescope will look at over its hopefully long life will be through the General Observer or GO program.

2022-09-14: Could the Higgs Boson Lead Us to Dark Matter?

  • 11:24: And the Higgs lives for only a fraction of a second before decaying. The hope is that sometimes it decays into a dark matter particle.

2022-08-03: What Happens Inside a Proton?

  • 08:30: ... time. No supercomputer   could do that even given the entire life of  the universe. For QED, Feynman diagrams let   us ...
  • 19:17: ... the death of the stars and live   to see the release of half life 3?” The worst part is that in a super deterministic ...

2022-07-27: How Many States Of Matter Are There?

  • 13:18: ... and culture, and how these changes may affect humanity and all life on ...

2022-07-20: What If We Live in a Superdeterministic Universe?

  • 01:22: But there’s one reality life raft that we haven’t touched - and that’s superdeterminism.

2022-06-30: Could We Decode Alien Physics?

  • 15:07: ... of traveling at relativistic speeds through  the dust and gas that lives between the ...
  • 15:41: ... the machines built by intelligent   civilizations than the lifeforms themselves. So you know who else that occurred to? One of ...

2022-06-22: Is Interstellar Travel Impossible?

  • 01:39: So today we’re going to explore this question - is humanity doomed to spend the rest of our species’ lifespan huddled in our own solar system?
  • 02:19: ... to travel the stars, travel time needs to at least be of order a human lifetime, which means traveling at relativistic speeds - sizable fractions of the ...
  • 02:47: These craft are little more than computer chips, and sending humans means many orders of magnitude more mass for life support and shielding.
  • 10:11: ... out that for the sorts of missions that might possibly happen in our lifetimes, our entire payload could be destroyed by gas without at least some ...

2022-06-01: What If Physics IS NOT Describing Reality?

  • 14:22: ... about what parts of the Milky Way   could potentially host life based on various  factors like abundance of necessary ...

2022-05-25: The Evolution of the Modern Milky Way Galaxy

  • 02:19: ... Weird to think that it built itself  into this through a life of violence. So   let’s look at what we know about galaxy ...
  • 12:11: ... accompanying supernova waves   may not be the best thing for life on Earth, but  we do have 2 billion years to get ready for ...
  • 14:38: ... with too much heavy element abundance might not  produce life because those systems would produce   too many gas giants. ...
  • 15:22: ... systems when we do these   calculations of the abundance of life-bearing  worlds. It’s because we’re trying to find the most   ...
  • 16:02: ... moon has been proposed as  an important factor in the appearance of life,   which may have first appeared in tidal  pools. The tidal pools ...
  • 16:41: ... high abundance of heavy elements - which was  perhaps necessary for life to get started.   The late heavy bombardment was a ...

2022-05-18: What If the Galactic Habitable Zone LIMITS Intelligent Life?

  • 00:24: ... to make it especially suitable for   developing and sustaining life, as we discussed  in our episode on the rare earth ...
  • 01:07: ... billion stars, why don’t we see  any other signs of technological life? This is the   Fermi Paradox, which of course we’ve talked ...
  • 02:20: ... food, and stability. It was a powerful,  never-tiring giver of life, and in mythology,   matters of life and death often get the ...
  • 04:32: ... like the galaxy should  be full of potential starting points for life,   even if we assume that life can  only form on Earth-like ...
  • 05:24: ... There are huge regions of the Milky Way where   life couldn’t possibly have formed, no  matter how perfect the host ...
  • 07:36: ... means they couldn’t possibly have formed  planets. No chance for life yet. However these   stars were incredible atom factories, ...
  • 08:01: ... waves   have now passed, so you might think  that life could take hold on the core.   Not so much. The metallicity of ...
  • 09:26: ... giant impacts  was probably good for driving evolution, but life   needs time to recover. Overly frequent mass  extinctions will ...
  • 10:04: ... they formed - again, not  the most likely places to find planets or life. ...
  • 11:12: ... we can say a little more about the emergence of  life-friendly planetary systems. And by “we”,   I mean Charlie Lineweaver, ...
  • 12:04: ... Way  have optimal conditions for the development of   life, and that would drop down to a percent or two  if we ruled out the ...
  • 13:03: ... factor that may explain the  apparent absence of technological life   is that other such civilizations just haven’t had  time to make ...

2022-04-27: How the Higgs Mechanism Give Things Mass

  • 15:06: ... with the Higgs field. Their mass shortened   their lifespans, and so enormously reduces their  range, weakening the force that ...

2022-03-30: Could The Universe Be Inside A Black Hole?

  • 05:19: ... hole singularity is the all-encompassing future for the spacetime that lives beneath the event horizon in the same way that the big bang is the ...

2022-03-23: Where Is The Center of The Universe?

  • 05:37: So could it be that there’s a higher dimensional space in which our 4-D hypersphere lives?
  • 14:59: ... the massive tides that the Proxima planets experience might be ideal for life due to the rich biodiversity of Earth’s intertidal ...
  • 15:10: I’m no expert, but I do remember that for a while tidal pools where thought to be a likely location for abiogenesis - the origin of life.
  • 15:27: But even if life didn’t start in tidal pools on Earth, who’s to say it couldn’t have happened that way elsewhere?
  • 15:52: On Earth, tectonic activity is essential for life due to its role in the carbon cycle.
  • 15:57: Life draws carbon from the atmosphere and sequestered in the crust.
  • 16:11: A hot interior may also have been essential for abiogenesis - if life really did first start around geothermal vents or hot springs.
  • 16:22: So in short those tidal forces on those Proxima planets may make it more likely that there's life.

2022-03-16: What If Charge is NOT Fundamental?

  • 08:21: ... must be something deeper - something that lives in the hearts of these quarks and other elementary particles - that ...

2022-03-08: Is the Proxima System Our Best Hope For Another Earth?

  • 09:09: Life?
  • 09:45: This situation doesn’t sound conducive to life for many reasons.
  • 11:03: In order for life to have a chance in this system, it needs to be protected from the star itself.
  • 13:02: Nonetheless, we’re focusing in on a relatively stringent set of requirements for this exoplanet to be able to support life.
  • 13:10: ... even if it’s a stretch, we need to imagine all the ways that life could have formed there, because that’ll help us build the instruments ...
  • 13:37: Both of these may bare the characteristic signatures of life, as we’ve discussed previously.
  • 14:28: After all, Proxima, with its many-trillion-year lifespan will far outlive our own Sun.
  • 15:51: ... much like the perpetual daytime on Proxima B, and the many-trillion year lifespan of a red ...

2022-02-16: Is The Wave Function The Building Block of Reality?

  • 13:19: ... and suck carbon from the sky. By answering a few questions about your lifestyle, you can find out your carbon footprint and how you can reduce it. No one ...

2022-01-19: How To Build The Universe in a Computer

  • 12:25: By answering a few questions about your lifestyle,  you can find out your carbon footprint and how you can reduce it.

2021-12-29: How to Find ALIEN Dyson Spheres

  • 00:00: In our search for alien lifeforms we scan for primitive biosignatures, and wait and hope for their errant artificial signals to happen by the Earth.
  • 02:23: ... might these be the best way to look for signs of intelligent life? ...
  • 06:37: ... star in the prime of its life settles into an equilibrium state in which the outward flow of ...
  • 06:47: If you know the mass of such a star, you can predict its size, its temperature, its brightness, its lifespan, and so on.
  • 08:50: ... stars that are in the primes of their lives - those powered by fusing hydrogen into helium in their cores - lie on ...
  • 09:03: ... off the main sequence when they expand into giants at the ends of their lives, or, presumably, when surrounded by giant alien astroengineering ...

2021-12-10: 2021 End of Year AMA!

  • 00:02: ... and finally managed to score a real job for the first time in my life at uh city university of new york lehman college that's my cv i do ...

2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light

  • 10:01: The authors say that more work is needed to verify that this is ruled out, but in general it looks like a lifeline for causality.

2021-09-21: How Electron Spin Makes Matter Possible

  • 14:58: ... of known physics. So thank you for interacting with us lowly, fermionic life-forms - our heads are spinning in gratitude for your ...
  • 18:44: ... Hey, at least you didn’t devote decades of your professional life to astrophysics before having that revelation. No, I’m kidding. I love ...

2021-08-18: How Vacuum Decay Would Destroy The Universe

  • 08:30: ... on  the properties of the elementary particles.   Life and structure could not exist as we know it, and may not exist at ...
  • 11:34: ... that a vacuum decay bubble   will reach us in the lifespan of our species,  let alone your own lifetime. Of course, in ...

2021-08-10: How to Communicate Across the Quantum Multiverse

  • 12:00: ... that the world where you made all of those better decisions about your life remains forever out of ...
  • 13:40: ... that if you’re looking for a fun show for the young scientists in your lives, than you should check out MEGAWOW on the PBS Kids Youtube Channel. This ...

2021-08-03: How An Extreme New Star Could Change All Cosmology

  • 01:45: ... what we thought we knew. When all but the most massive stars end their lives, they blast off their outer layers in their final fits of nuclear fusion. ...

2021-07-13: Where Are The Worlds In Many Worlds?

  • 10:38: And, I don’t know, maybe next to the love of your life, who convinces you to leave research and start a small bed and breakfast in Argentina.
  • 10:46: Two lives diverge, and worlds are irreconcilably split.

2021-06-09: Are We Running Out of Space Above Earth?

  • 12:24: At the very least, the cost of maintaining a satellite presence will be prohibitively expensive with satellite lifetimes dropping drastically.

2021-05-11: How To Know If It's Aliens

  • 00:52: ... if the microbes had been fried It seemed like a slam dunk detection of life on Mars. And yet no other Mars mission has managed to detect clear ...
  • 01:24: ... half century we get another tantalizing hint of the existence of alien life. But they all seem to fizzle out - at least, we never get the grand ...
  • 01:55: ... start - or rather continue with our quest to find evidence of primitive life in our solar system. The Viking mission’s labeled release experiment ...
  • 03:08: ... look as some of the other hints in our solar system. Still on Martian life, what ever happened to that supposed fossil microbe found in that Martian ...
  • 03:17: ... the presence of liquid water. This was a compelling enough hint at life that Bill Clinton made a special TV ...
  • 03:54: ... why don’t we count this as the discovery of life on Mars? Over the past couple of decades, researchers have shown how ...
  • 04:11: ... but they don’t need to. When we’re talking about the discovery of alien life, the burden of proof rests very heavily on the shoulders of the ...
  • 04:45: ... at least be very cautious about - all prior claims of evidence of alien life. For example, the occasional spikes in methane detected by the Curiosity ...
  • 13:10: ... is - When do we believe some new hint or claim of the detection of alien life? That’s easier to answer - optimistic skepticism is the way to go. ...

2021-04-21: The NEW Warp Drive Possibilities

  • 14:33: The problem is that the tau’s lifetime is around 10 million times shorter that the muon, which itself lives only for only microsecond or so.

2021-02-17: Gravitational Wave Background Discovered?

  • 00:00: ... buzz the gravitational wave background and it could reveal the lives of the most massive black holes in the universe and provide a glimpse ...

2021-02-10: How Does Gravity Warp the Flow of Time?

  • 00:00: ... the course of your life your feet will age approximately 1 second more than your head due to ...

2021-01-26: Is Dark Matter Made of Particles?

  • 06:06: It would also be a no-brainer Nobel prize - and many researchers have devoted their lives to hunting down this particle.
  • 13:10: ... US How they're changing and how you can prepare. This is literally a life saver. Like this saves peoples lives. In the last episode we asked the ...

2020-12-22: Navigating with Quantum Entanglement

  • 00:08: ... in his 1944 book, What is Life?, the quantum physicist Erwin Schrödinger suggested that “incredibly small ...
  • 08:43: ... during the short lifespan of the radical pair, its valence spin state can be modified if the bird ...

2020-12-15: The Supernova At The End of Time

  • 02:54: On one of those planets - the third one out - a steamship is making its slow journey to a place that the local carbon based lifeforms call “England”.
  • 06:39: Not a bad start to graduate school - showing up on your professor’s doorstep having already improved one of your prof’s major life achievements.

2020-12-08: Why Do You Remember The Past But Not The Future?

  • 01:26: On longer timescales when we think back we remember the events of the day, of the last month, or of our lives.

2020-10-20: Is The Future Predetermined By Quantum Mechanics?

  • 00:52: ... that for every observer it's possible to imagine another observer who lives in their definition of the present, but for whom your future is already ...

2020-10-13: Do the Past and Future Exist?

  • 10:19: ... universe that couldn't be considered the past according to someone who lives in our ...
  • 13:29: Remember, it's probably not life - but it just might not not be. . .
  • 13:36: ... Williams points out that any Venusian life that we find is very likely from Earth - having transported to Venus on ...
  • 13:44: And Afto Kinito points out that it could easily have happened in the other direction - Earth life being seeded by Venusian meteorites.
  • 14:03: ... question then becomes - would it have been easier to kickstart life from scratch on two planets independently, or have a spacefaring bugs ...
  • 14:22: ... takes issue with my statement that it would be good news if the venus life was confirmed, pointing out that it would mean the great filter is in ...
  • 14:47: ... ... Or it may be behind us, like it might be extremely difficult for life to form in the first ...
  • 15:01: If we discover that life forms very easily - for example by discovering it on Venus, then it makes it more likely that the great filter is ahead.
  • 15:12: So yeah, maybe - but there are still plenty of past great filters, like evolving complex lifeforms or intelligence or whatever.
  • 15:19: Or maybe life did only spawn once in our solar system and then spread.
  • 15:23: Either way, I'm still rooting for life on venus.
  • 15:26: ... so maybe we just discovered Venusian heavy industry and not microbial life. ...

2020-10-05: Venus May Have Life!

  • 00:11: In fact we may have detected the signature of alien life - Venusian life -for the first time.
  • 00:23: ... searches for life-beyond Earth have tended to focus on the Martian subsurface and the ocean moons ...
  • 00:32: And yet the horrible hellhole that is the atmosphere of Venus has just yielded perhaps the most exciting lead for extraterrestrial life.
  • 00:47: I joked more that the weirdest end to this very weird year would be the discovery of alien life.
  • 02:36: This could be due to dust churned up from the surface - or it could be gigantic colonites of microbial life.
  • 03:05: ... Carl Sagan and Harold Morowitz were among the first to suggest that life might exist permanently aloft in Venus’s relatively habitable upper ...
  • 03:31: ... of the most promising avenues in the search for life is to detect so-called atmospheric biosignatures - chemicals in a ...
  • 05:06: And if so, how likely is it that the phosphine came from life?
  • 05:31: Okay assuming it is real, does this mean we’ve found life?
  • 05:35: Well, let’s first discuss why the presence of a simple molecule might get people excited about the possibility of life.
  • 06:17: ... features of phosphine in the two gas giants - but no one screamed life, because there’s a clear mechanism for producing that phosphine by ...
  • 07:32: So we’re left with two possibilities - either there’s some unknown non-biological process that produced this phosphine, or Venus has life.
  • 07:51: But this may be the most promising lead to extraterrestrial life we’ve ever had, so let’s talk about what that life might look like.
  • 08:07: But the requirements for life in the clouds of Venus are pretty strict.
  • 08:11: ... entire lifecycle would have to remain in the regions with survivable temperature and ...
  • 08:21: Sara Seager from MIT and collaborators proposed a lifecycle that might just do the trick.
  • 08:32: ... environments are universally thought to be essential to life, and in the extreme dryness of the Venusian atmosphere free-floating ...
  • 10:03: The life cycle would look like this: microbes are in a metabolic state in sulphuric acid droplets in the upper atmosphere.
  • 10:49: We just don’t know if life can exist in those conditions.
  • 11:04: ... lifeforms in its atmosphere today must have evolved from presumably much more ...
  • 11:44: But ultimately we’re going to want to go to Venus, to search for life signatures there or, even better, to bring samples back to Earth.
  • 11:57: Neither mission has a direct life-detecting instrument, but that might change given these developments.
  • 12:15: The discovery of alien life in our nearest planetary neighbor would totally change our calculations about the frequency of life in the universe.
  • 12:23: We may be forced to conclude that life is cosmically abundant.
  • 12:29: ... good news - granting us a grander perspective on humanity’s place in a life-filled space ...

2020-09-28: Solving Quantum Cryptography

  • 01:08: ... could use a quantum computer to factor a prime number in, well, a human lifetime, or a human ...
  • 14:24: Last week we talked about a highly speculative idea - lifeforms inside stars, formed from cosmic strings and magnetic monopoles.
  • 14:30: ... than chemical reactions - so what would be the timescale of evolution or lifespan of these ...
  • 15:19: That would suggest slower timescales than the evolution of chemical life.
  • 15:52: So that bizarre electric monopole-based life is us.
  • 16:25: Some of you thought it was funny that we would do an episode on life in the sun right after the potential discovery of life on venus.
  • 16:39: The life on venus episode will follow soon, don't worry.
  • 16:42: ... besides, don't you think it's important to understand possible life in the sun before we decide what diplomatic relations to develop with ...
  • 17:05: ... and we're orbited by specks of dust infested with some sort of mud-based life. ...

2020-09-21: Could Life Evolve Inside Stars?

  • 00:00: Science fiction has come up with countless ideas for weird forms of life not based on boring old DNA, or even on matter as we know it.
  • 00:16: Oh, and here’s an extra crazy one - life composed of cosmic strings and magnetic monopoles, evolving in the hearts of stars.
  • 00:33: Scientists can sometimes be a little carbon-chauvanistic when we imagine other possible life forms.
  • 00:45: But could some other mechanism exist that could allow the incredible chemical diversity needed to power life?
  • 00:58: One of the most bizarre proposals for life not as we know it doesn’t even use atoms.
  • 01:03: ... with magnetic monopoles - may evolve into complex structures, and even life, within ...
  • 04:27: ... and Chudnovsky imagine a type of nuclear life, in which these chains form complex structures that can have a sort of ...
  • 04:46: The authors lay out three conditions for life that they investigate.
  • 04:55: Fair enough - our DNA encodes all the instructions our cells need to build the molecular machinery of life.
  • 05:01: It’s hard to imagine a life form that didn’t have a way to store information.
  • 05:24: This is something we know is essential for any life, including nuclear life.
  • 06:45: OK, moving on to life condition number 2: can these information carriers replicate faster than they can disintegrate?
  • 07:53: And finally, life condition number 3: do we have a source of free energy?
  • 08:35: For example, life uses the energy flowing from the high energy-density of the Sun to the lower energy density of the Earth.
  • 08:42: In fact we talked about all of that in our episode on the physics of life.
  • 08:47: We saw that these temporary increases in order, represented by life, actually speed up the process of smoothing out all of the energy.
  • 08:56: Little low-entropy blips like life ultimately accelerate the increase in entropy of the universe.
  • 09:09: It’s conceivable that a lifeform could harness that flow.
  • 09:40: ... and it might be a little premature to claim discovery of a new lifeform. ...
  • 09:50: ... whether they can interact with the complexity needed to evolve into life. ...
  • 10:03: ... is likely - their point is more to show that other possible bases for life might exist, beyond the familiar carbon ...
  • 10:23: And who knows what other bizarre life forms may be waiting to be discovered, in distant, stranger parts of space time.

2020-09-01: How Do We Know What Stars Are Made Of?

  • 11:04: ... PBS is asking you to share your stories, experiences and ideas on your life in America ...
  • 11:15: PBS American Portrait is a nationwide storytelling project — a chance to be seen, heard, and to give a glimpse into your own life.
  • 11:31: Since the first Target opened in 1962, their mission has been to help families discover the joy of everyday life.
  • 11:37: In all 50 states, Target is dedicated to being a good neighbor, and working with their communities and partners to make life a little better.

2020-08-24: Can Future Colliders Break the Standard Model?

  • 10:11: The Future Circular Collider will cost 10s of billions over its life.

2020-08-10: Theory of Everything Controversies: Livestream

  • 00:00: ... then we should challenge them in the laboratory and we should retool life's a lot weirder than that and the key problem with beauty is that it's ...

2020-07-28: What is a Theory of Everything: Livestream

  • 00:00: ... multiple books including our mathematical universe and the recent book life 3.0 so uh hi everyone thanks for joining us hello it's a pleasure to ...

2020-06-15: What Happens After the Universe Ends?

  • 03:08: ... the life of both universes, those rays trace out the same pattern - all the ...
  • 15:40: Drakenkorin27, who is a bona fide virologist, gave us even more reason to doubt that any viruses from space have ever infected earth life.
  • 15:47: I had pointed out that alien viruses would need to be DNA-based in order to infect DNA-based life.
  • 15:54: ... points out that the DNA of all life that evolved on earth uses the same code for instructing the molecular ...
  • 16:27: MC’s creates notes that if the RNA world hypothesis is correct, then viruses were the first "life" to appear on Earth.
  • 17:30: And if it was actually alien life?

2020-06-08: Can Viruses Travel Between Planets?

  • 00:50: That’s right, viruses or their ancestors may have played a role in the origin of life on earth, and may be needed to initiate life on any planet.
  • 02:14: The term virus better describes the entire microbal lifecycle, and inside an infected cell, a virus has no shell - it is the genetic material.
  • 02:40: One thing viruses do share in common with life is the ability to evolve.
  • 03:00: But viruses aren’t just masters of their own evolution - it seems they may be an essential driver of the evolution of cell-based life.
  • 03:46: RNA-based viruses in particular may have emerged from the pre-cellular RNA world, which would make them our most distant cousins on the tree of life.
  • 03:57: Or tree of "life"?
  • 03:59: ... from RNA-based pseudo-life to the first true DNA based cellular life. ...
  • 04:14: Understanding viruses may be the key to understanding the origin of life.
  • 04:32: ... of the most promising prospects for our first detection of alien life is to find signatures of its chemical activity in the atmospheres of ...
  • 04:57: Cellular life massively alters the atmosphere because it excretes gases - oxygen, methane, nitrous oxide as that light metabolizes.
  • 05:40: The first stop in our search for life is always Mars.
  • 05:45: ... days, but it’s conceivable that an ecosystem of extremely hardy microbes lives beneath the Martian surface. And some viruses are among the hardiest of ...
  • 06:19: If those oceans contain microbial life, then they may also contain viruses.
  • 11:37: But one thing they all have in common is that viruses all infect life as we know it.
  • 11:55: That would only be the case if DNA/RNA based life was the norm for extraterrestrial life.
  • 12:04: Perhaps DNA is the only possible basis for complex life, or perhaps panspermia seeded DNA-based life and DNA-preying viruses across the galaxy.
  • 13:13: ... always lived alongside us, driven our evolution, and perhaps predated life itself - the world of viruses, our currently not-so-favourite, but still ...

2020-05-11: How Luminiferous Aether Led to Relativity

  • 01:34: ... today we’re going to celebrate the life and death of an idea. As with so many ideas, the aether was born in the ...
  • 04:06: ... the channel, a much younger Isaac Newton was sitting in Cambridge making life difficult for Huygens. First his theory on universal gravitation ...

2020-05-04: How We Know The Universe is Ancient

  • 06:22: ... Hubble’s great discovery, thousands of astronomers have devoted their lives to measuring the Hubble constant - and a big part of the motivation is ...

2020-04-28: Space Time Livestream: Ask Matt Anything

  • 00:00: ... know a the perhaps the most famous example of that is Conway's Game of Life which you've all seen it I think if not google it but by the way John ...

2020-04-14: Was the Milky Way a Quasar?

  • 14:47: ... U-238 has a shorter half life so first it decays quickly in the first couple of billion years, then ...

2020-03-24: How Black Holes Spin Space Time

  • 11:31: ... gamma ray bursts. When a truly gigantic star collapses at the end of its life, and if its core was rotating fast enough, that core will produce a Kerr ...

2020-03-03: Does Quantum Immortality Save Schrödinger's Cat?

  • 00:11: If the quantum multiverse is real there may be a version of you that lives forever.
  • 09:08: Depending on some assumptions like the average lifespan you get that something like 17-18 trillion people will have lived by the year 3000.
  • 09:36: ... Bayesian analysis or thinking in “observer years” rather than observer lifetimes. ...
  • 10:04: That would push the 99% doomsday date to something like 10,000 years from now if we extend our average lifespan to 100 years.

2020-01-13: How To Capture Black Holes

  • 00:59: ... massive stars are in binary orbit with each other, they may end their lives to leave a pair of binary black holes. And in very dense environments ...

2020-01-06: How To Detect a Neutrino

  • 04:59: ♪ ♪ ♪ ♪ So: the briefer the lifetime of this virtual boson, the more energy it's allowed to borrow.

2019-12-17: Do Black Holes Create New Universes?

  • 00:30: Why, for example, are the fundamental constants - like the mass of the electron or the strength of the forces - just right for the emergence of life?
  • 00:37: Tweak them too much and life, stars, galaxies, the universe as we know it wouldn’t exist.
  • 00:50: ... then it’s not surprising that a few exist with the right numbers for life - and certainly not surprising that we find ourselves in one of those ...
  • 01:21: It has finely tuned parameters that seem deliberately set for a particular outcome - life.
  • 01:29: There’s another example in nature where the illusion of design has a perfectly natural explanation - and that’s life itself.
  • 02:43: Now by happy chance there’s a correlation between making lots of black holes and making life - both require stars.
  • 07:00: ... would form - and of course these factors also seem to be essential for life. ...
  • 08:30: And naturally we’d find ourselves on one of those branches because those also happen to be the ones that favour life.
  • 08:51: ... completely independently to those that also favour the appearance of life. ...
  • 10:59: ... and it’s just a happy coincidence that the same factors also favor life. ...
  • 11:13: ... boron that helped stars form - or other elements that were useless to life. ...
  • 11:27: ... the selection process for cosmic reproduction from the emergence of life then it seems we still have to invoke a good lot of good ...

2019-12-09: The Doomsday Argument

  • 00:25: ... and our universe seem very finely tuned to allow the development of life. ...
  • 02:24: But it’s a good thing ours IS low because otherwise our universe would have blown itself up too quickly for stars and life to ever form.
  • 06:07: ... and ultimately gives rise to a hundred trillion trillion individual lives - ...
  • 06:55: We can imagine that the two scenarios are our two boxes - the doom-late box contains 10^20 lives and doom-soon contains 10^11.
  • 07:17: So which is more likely - that your birth rank happens to be somewhere around the mid-point of the species lifespan?

2019-11-18: Can You Observe a Typical Universe?

  • 03:31: ... conditions that seem extremely fine-tuned for the eventual formation of life. ...
  • 03:44: ... and their properties can vary, then even if the vast majority are lifeless, life-friendly universes can still show ...
  • 04:04: And we shouldn’t be surprised that we find ourselves in one, even though Earth and a life supporting universe might be quite atypical.
  • 05:50: ... since - from the formation of stars and galaxies to the evolution of life - has been powered by the slow increase in entropy from that initial ...
  • 06:01: ... universe will spend the vast majority of its perhaps-infinite life in a state of extreme disorder and high entropy - iron stars, black ...
  • 08:48: ... surely don’t need more than one galaxy to spawn a life-bearing planet - so there should be many more observers in small entropy ...
  • 09:32: ... fluctuations to evolve and expand for the right amount of time, so that life may always be in big ...
  • 11:12: Carbon-based sentient life?
  • 14:08: ... we talked about how the constants of nature seem to be fine tuned for life in our universe - and how this may imply that there are countless ...
  • 14:21: ... objection: they say that the universe isn't really fine-tuned for life or for observers because there could be many types of observer very ...
  • 14:43: ... be capable of forming complex structures - whether or not it looks like life as we know ...
  • 15:44: ... that principle is somehow connected to the universe's later developing life and structure, why should it have landed on one of the rare combinations ...
  • 15:59: ... combination of fundamental constants that was completely devoid of life. ...
  • 16:11: So I still count this option as either "getting lucky" or that the later emergence of life was somehow retrocausal of the universe's knob-setting.
  • 16:26: ... great point: surely if this were the Goldilocks universe there would be life on almost every planetary body, even in this solar ...
  • 16:57: ... get set - it may be improbable to get those constants fine-tuned for life - but the more fine-tuned they are, the more ...
  • 17:18: ... own fine tuning that may be just as bad as the fine tuning needed for life in our ...

2019-11-11: Does Life Need a Multiverse to Exist?

  • 00:03: Life exists in our universe.
  • 00:07: Therefore our universe is capable of producing and supporting life.
  • 01:44: ... vastly different - and probably unable to produce galaxies, or stars, or life. ...
  • 01:58: ... just happened to land in the very narrow range of numbers that allow life to form. Or 2) someone fiddled with the dials - be it god or whoever ...
  • 03:13: ... themselves, neither version of the anthropic principle explain why life-friendly planets or universes exist; they just say that if such places do exist ...
  • 04:18: ... are capable of forming structures of incredible complexity - including life. ...
  • 04:40: But it wasn’t at all inevitable that our universe had to be capable of life-enabling chemistry, or of complex chemistry at all.
  • 05:28: Carbon would no longer be abundant on the surfaces of new planets, making the emergence carbon-based life near impossible.
  • 05:49: If it were half a percent higher or lower, carbon-based life wouldn’t be a thing.
  • 06:12: ... stars - meaning all stars in the universe would have burned out before life ever got a ...
  • 08:15: But they also seem tuned for life.
  • 10:35: But even so, odds are stacked enormously against a universe that doesn’t blow itself up before life has a chance.
  • 10:55: ... maybe we’re just in one of the few universes with the right physics for life - just like we’re on one of the few planets with the conditions suitable ...
  • 13:09: ... the Rare Earth Hypothesis - the idea that planets supporting intelligent life may be extremely rare, and how this relates to the weak anthropic ...
  • 14:24: If life requires smaller rocky planets rather than super-earths then this could definitely be a rare-earth property.
  • 14:34: ... we talk about are needed for OUR evolutionary tree, but other types of life are no doubt ...
  • 14:52: ... don't know if any one rare quality of Earth is absolutely necessary for life, there do seem to be quite a lot of qualities that are very non-standard ...
  • 15:08: ... - yeah you might be able to get different types of complexity and even life by tweaking the fundamental constants in different ways, but there seem ...
  • 16:03: ... event, the first evolution of the eukaryote cell, took at least half of life's entire evolutionary history to ...

2019-11-04: Why We Might Be Alone in the Universe

  • 01:44: When combined with the apparent absence of alien civilizations, it may tell us that intelligent life is incredibly rare in our universe.
  • 02:33: For example, if there’s only one life-bearing planet in the galaxy, or in the universe, you’re going to be on it.
  • 02:40: ... Earth exceptionally unusual and uniquely able to produce intelligent life. ...
  • 03:05: ... between the massive abundance of potential opportunities for technical life to have emerged and spread through our galaxy and the apparent lack of ...
  • 04:14: It highlights a series of remarkable qualities of planet Earth that may have been needed for life and intelligence to arise here.
  • 04:53: ... billions of potential starting points for life in the Milky Way alone, even if we restrict ourselves to boring old ...
  • 05:16: Let’s think about what Earth’s has got that seems critical for life and that could be unique.
  • 05:21: If we see that even one other planet has some life-critical quality, then we know that that quality could be relatively common.
  • 06:44: Without this biogeochemical cycle, many life-critical elements may have been lost to the biosphere long ago.
  • 06:51: So Earth’s dynamic interior seems to be life-critical in multiple ways.
  • 07:36: It may also be that our moon and the event that formed it was critical to the development of life.
  • 07:58: Too large a tilt and seasons become too extreme for life to thrive.
  • 08:22: And a final possible result of our weirdly large moon is that it enabled the first appearance of life.
  • 08:32: ... hypothesis for the first formation of life is that it evolved in tidal pools, with complex chemicals and eventually ...
  • 09:35: And yet Jupiter in particular was probably pretty important for the development of life.
  • 10:01: Perhaps life would have been wiped out entirely.
  • 10:24: Perhaps life is extremely common - or at least extremely simple life is common.
  • 10:29: ... steps that happened in the evolutionary transition from single-cellular life to complex life, or to ...
  • 11:29: ... of Earth’s life-critical qualities or development steps have not been seen elsewhere, nor do they ...

2019-09-30: How Many Universes Are There?

  • 06:31: ... its accelerating expansion too quickly for galaxies and stars and life to ever ...
  • 06:51: ... that at least some will have a low enough cosmological constant for life to ...
  • 07:06: ... universes it is natural that we find ourselves in one finely tuned for life. ...
  • 08:24: All different vacuum states exist, and our universe necessarily has one that leads to life-friendly particles.
  • 09:24: Now, imagine that there’s a set amount of time for the first intelligent life to form in any one of these universes.
  • 10:01: One second later – “second two” – you might get some more intelligent lifeforms forming in those same universes.
  • 10:18: These are only now reaching the 10 billion year mark and producing their first intelligent lifeforms.
  • 10:45: ... are in the youngest universes that have had time to form intelligent life. ...
  • 10:58: ... if we imagine that we are a typical intelligent lifeform, then we’re most likely the most common type across the multiverse, which ...

2019-09-23: Is Pluto a Planet?

  • 11:57: For example, the moons of Jupiter and Saturn are active worlds that may prove to be the only other homes for life within our solar system.
  • 14:58: Dwarf planet David is a frigid, lifeless ball of ice and rock half the mass of Pluto and orbiting at the outer rim of the Kuiper belt.
  • 16:27: ... is several months long, and that's a long time for any photosynthesizing life to survive without the sun, and 2) it has essentially no water, so we'd ...
  • 18:00: It's not like any of the previous life-obliterating comet swarms because this one will be controlled by mindless robots.

2019-09-16: Could We Terraform Mars?

  • 00:13: Life will blossom in our path and eventually the galaxy will shimmer with beautiful Earth-like orbs.
  • 10:00: In fact, it’s instantly and fatally toxic to humans and animals, and not so great for plant life.

2019-09-03: Is Earth's Magnetic Field Reversing?

  • 01:15: Would life be extincted by crazy space radiation?
  • 12:24: ... and think that Earth’s magnetic field is likely to hold out for our lifetimes – and those of some generations to ...

2019-08-26: How To Become an Astrophysicist + Challenge Question!

  • 03:35: ... working your butt off as an undergraduate will help you learn whether a life in science is really for you You may end up finding out that your ...
  • 08:47: The reasons to do it you want to spend your life answered the biggest questions there?

2019-08-19: What Happened Before the Big Bang?

  • 13:05: What's the meaning of life, the universe and everything?
  • 13:08: 42 for the right definition of life, the universe, and everything.

2019-08-12: Exploring Arecibo in VR 180

  • 00:06: It's the only known world in the universe with life. Come closer. You can see this.

2019-07-25: Deciphering The Vast Scale of the Universe

  • 09:33: ... the size of the Universe is enormous, why haven’t we seen other signs of life? ...

2019-06-17: How Black Holes Kill Galaxies

  • 10:49: ... galaxy would survive and perhaps for the best - for the comfort of the life bearing world to leave raging starbursts and fiery quasars to an earlier ...
  • 12:35: But, that stuff probably isn't essential to life.

2019-06-06: The Alchemy of Neutron Star Collisions

  • 00:34: ... in the cores of very massive stars during the last phases of their lives and that elements heavier than iron were synthesized in the following ...
  • 02:47: ... solar system and those atoms would eventually find themselves part of a life-form that would figure out the very time and distance of their formation a ...

2019-05-01: The Real Science of the EHT Black Hole

  • 11:22: ... you can check out Stephen Hawking's Favorite Places, which explores the life of the late, great Hawking, as well as everything from the Big Bang to ...

2019-04-24: No Dark Matter = Proof of Dark Matter?

  • 00:03: ... cluster was mapped using gravitational lensing this time the warping of life of galaxies behind that cluster it turns out that most of the mass ...

2019-04-03: The Edge of an Infinite Universe

  • 17:16: Swole Kot asks if the last months in the big rip scenario would be a painful and horrible experience for any sentient life still around at that point.

2019-02-20: Secrets of the Cosmic Microwave Background

  • 01:34: ... through the first few hundred thousand years of the Universe's life. ...

2019-02-07: Sound Waves from the Beginning of Time

  • 01:37: For the first few hundred thousand years in the life of our universe, All of the space was filled with hydrogen and helium in plasma form.

2019-01-24: The Crisis in Cosmology

  • 03:18: ...giant stars, during the last phases of their lives.

2019-01-16: Our Antimatter, Mirrored, Time-Reversed Universe

  • 03:02: ... The KS particles should never have made the journey given their short lifetimes and yet a small but significant number of decay products from KS ...

2018-12-20: Why String Theory is Wrong

  • 13:44: ... principle the standard model lives somewhere in the string landscape, but without knowing the geometry of ...

2018-12-12: Quantum Physics in a Mirror Universe

  • 00:02: ... visit us on patreon now last time we talked about a wild notion for how life may have originated on earth perhaps it came from space let's see what ...

2018-12-06: Did Life on Earth Come from Space?

  • 00:03: ... if the first genesis of life the abiogenesis is so unlikely that it only happened once in the entire ...
  • 00:37: ... cells in that geological eyeblink well maybe but it's also possible that life on Earth didn't start on earth at all perhaps it started on a distant ...

2018-11-21: 'Oumuamua Is Not Aliens

  • 10:43: ... why build a probe that travels at such a snail's pace, surely beyond the lifespan of any aliens who sent it, especially when the technology to accelerate ...

2018-10-31: Are Virtual Particles A New Layer of Reality?

  • 15:24: A hard filter is a step in development that's so unlikely it can cut off nearly all progress for development of life or civilization.
  • 15:37: That's the transition from what we'd call not intelligent to intelligent life.
  • 16:04: ... though, it's not right to say that it took the span of life on Earth for this fluke to happen-- as if we were rolling the dice every ...
  • 16:15: A lot of that time, life was evolving towards the point that it could become intelligent.

2018-10-25: Will We Ever Find Alien Life?

  • 00:36: ... of billions of stars, each of which having billions of years to spawn life and civilization, isn't it odd that none have made themselves apparent ...
  • 02:26: And how many of these planets have life?
  • 02:42: Life is expected to massively alter the chemical composition of its home world atmosphere.
  • 02:57: There is a good chance we'll have found hard evidence of extraterrestrial life in the next decade or so.
  • 03:03: But that's regular, old, non-technological life.
  • 06:32: That still seems surprising given those 40 billion possible starting points for life in the Milky Way.
  • 07:23: ... biological factors like the frequency of the appearance of simple life and the proportion of those that lead to intelligent life, and ...
  • 08:46: ... a less stringent limit on this likelihood by assuming that a lot of life gets wiped out by gamma ray bursts, a type of cataclysmically exploding ...
  • 12:40: The alternative may be eternal quiet across the lifeless reaches of space time.

2018-10-10: Computing a Universe Simulation

  • 01:22: In this picture, the universe is a multi-dimensional version of Conway's game of life.

2018-09-20: Quantum Gravity and the Hardest Problem in Physics

  • 11:27: Generations of physicists, starting with Einstein himself, spent their lives trying to fix this to unite quantum mechanics and general relativity.

2018-09-12: How Much Information is in the Universe?

  • 11:30: ... going to catch up on responses to the life on Mars and the end of the universe episodes today, and next week, we'll ...
  • 11:40: ... with our episode on the history of life on Mars, sdushdiu says, Cool, the show is current enough to acknowledge ...
  • 13:09: Not saying there was life-- I have to look deeper into that-- but this highlights the danger in simple interpretation of secondhand reports, i.e.

2018-08-30: Is There Life on Mars?

  • 00:03: Has there ever been life on Mars?
  • 00:11: ... MUSIC] There is no greater hero in our search for life on Mars than a little robot named "Opportunity." 15 years after its ...
  • 00:31: ... quest that "Opportunity" has contributed so much to-- the search for life on ...
  • 00:59: But at the end of July, something remarkable was announced that may prove the possibility of life on Mars.
  • 01:11: And in 2020, the race to find life on Mars will intensify with both ESA and NASA launching missions.
  • 01:19: They'll shift the focus from the search for water-- because we now know there is water-- to the search for life, past or present.
  • 01:32: Applying our best earthbound technologies to an uncontaminated sample may provide the proof of Martian life we've always been hoping for.
  • 01:41: ... we have to suggest some caution because people have been searching for life on Mars and believing they found it for over 300 ...
  • 01:51: So today, we're going to look back at the long history of life on Mars or, at least, of our hunt for it.
  • 02:27: In fact, he was the first to postulate that liquid water is necessary for life.
  • 03:38: ... of that very human bias because it's led to the erroneous discovery of life on Mars on multiple ...
  • 05:10: Lowell wrote three books on the subject, the last presenting his full theory on the subject of life on Mars.
  • 05:16: ... popularized the belief in the general public of life on Mars, ultimately inspiring works of fiction like HG Wells, "The War ...
  • 06:07: They conducted four experiments looking for the biosignatures of past or present microbial life.
  • 07:48: This direct detection of extraterrestrial life even prompted an announcement from President Clinton.
  • 09:29: But unexpected cleaning events from the Martian wind cleared those accumulations, allowing the massively extended lifespans of both rovers.
  • 10:20: And that's actually bad news for life.
  • 10:41: 2018 has been a great year for the possibility of life on Mars.
  • 11:12: We find small organic molecules in lots of places that life has never touched.
  • 12:47: So, do I think there's life on Mars?
  • 12:57: It didn't take life that long to get started on Earth.
  • 13:07: ... even one incident of life beginning on another planet would tell us worlds about the likelihood of ...

2018-08-23: How Will the Universe End?

  • 01:44: Life and structure can only exist as long as the universe is not in perfect equilibrium, what we call heat death.
  • 02:51: Those white dwarfs will fade to black in only several billion years, far shorter than the several trillion-year lives of those stars.
  • 03:00: And what happens to life in that era?
  • 08:25: If life manages to master this energy source, then its future history could be as ridiculously long as the Black Hole Era.

2018-08-01: How Close To The Sun Can Humanity Get?

  • 00:08: The source of all life and sustenance for our little blue space rock.
  • 01:15: But that energy doesn't only come as life-giving light.

2018-07-25: Reversing Entropy with Maxwell's Demon

  • 00:31: As we saw in our episode on the physics of life, structure can develop in one region even as the entropy of the universe rises.
  • 13:20: ... wanted to let us know that the Go board made him think of the game of Life and wonder whether the universe is a giant quantum cellular automata, ...

2018-07-18: The Misunderstood Nature of Entropy

  • 10:33: We talked a little about this in our episode on the physics of life, where we saw how entropy drives both the increase and decay of complexity.

2018-05-23: Why Quantum Information is Never Destroyed

  • 13:34: Black hole memory leaks, quantum rounding errors, and it took 10 billion years to compile the first life form.

2018-05-16: Noether's Theorem and The Symmetries of Reality

  • 08:53: During her life, she was repeatedly refused any paid academic position due to her gender, until late in her career.

2018-05-09: How Gaia Changed Astronomy Forever

  • 02:58: For example, stars on this diagonal band-- the so-called, main sequence-- are in the primes of their lives, fusing hydrogen into helium.
  • 03:39: ... of evolutionary paths that may reveal the composition and past life of the white ...
  • 04:04: These are stars near the ends of their lives, now burning helium in their.
  • 09:26: And we expect them to pass through white, and some to blue, at the ends of their lives.

2018-05-02: The Star at the End of Time

  • 00:10: How long will life persist as the stars begin to die?
  • 01:02: How long can life survive into the far future?
  • 01:05: ... absolute requirement for the continued existence of life is energy or, more accurately, a persistent energy gradient, as we've ...
  • 01:15: For life to stave off rising entropy and decay, energy must flow.
  • 01:25: When the last star blinks out, life must soon follow.
  • 01:29: To know the future of life, we must understand the life cycles of the longest-lived stars in the universe.
  • 01:41: They have very, very bright futures and may even spawn a renaissance of life trillions of years from now.
  • 02:41: ... is all astro 101, so let's get a little crunchy and figure out the lifespan of red dwarf stars, also known as "M dwarfs." We observe that a red ...
  • 03:53: Over the course of its long life, a red dwarf will convert all of its hydrogen to helium.
  • 04:25: The heating core causes red dwarf fusion rates to increase by a factor of 10 or more, particularly towards the ends of their lives.
  • 04:32: That shortens their lifespans, but we're still talking trillions of years.
  • 05:31: For most of its life, the spectrum of a red dwarf peaks at infrared wavelengths.
  • 05:52: In the final few billion years of their lives, some red dwarfs may even become hotter than our Sun, developing a faint blue tinge.
  • 06:21: So what does this mean for the future of our galaxy and for any life that exists then?
  • 06:26: Well, long before the first red dwarfs approach the ends of their lives, there will be no other living stars left in the galaxy.
  • 07:30: But what about new life?
  • 07:43: We don't know yet whether life can evolve around red dwarf stars.
  • 07:46: They're violently active when they're young, but perhaps ancient red dwarfs will have the stability needed for new life to take hold.
  • 07:57: ... a period of relatively constant brightness right at the ends of their lives. ...
  • 08:26: So could life begin from scratch in a trillion years right as the red dwarfs begin to die?
  • 08:33: It's very possible that most of the life in the universe is yet to evolve.
  • 08:38: ... Milky Way will be there to witness this, one last long renaissance of life as we huddle in the warmth of the last stars to burn in the darkening ...

2018-04-25: Black Hole Swarms

  • 02:11: Black holes form when the most massive stars end their lives in spectacular supernova explosions.
  • 04:15: Over the life of the Milky Way, they have piled up in the galactic core, forming a giant nucleus star cluster.

2018-04-18: Using Stars to See Gravitational Waves

  • 10:12: So, last week's episode was a mega collaboration with PBS "Eons" and "It's OK to Be Smart," tackling the giant question, what is the origin of life?
  • 10:22: Our episode was on the physics of life.
  • 10:57: Bose-Einstein asks, is life causing the universe to reach high entropy faster than if life didn't exist?
  • 11:10: Life reduces the Earth's albedo, it's reflectivity.
  • 11:14: Without life, Earth would reflect a higher intensity spectrum closer to the 6,000 Kelvin thermal spectrum it receives from the sun.
  • 11:42: Slimthrall suggests a flaw in the idea that life is a mechanism for increasing entropy.
  • 11:47: The suggestion is that, if this were true, then life should be much more common, more common than not wherever conditions are vaguely favorable.
  • 12:27: That appears to be the case with life.

2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)

  • 00:06: So how did it generate the extreme complexity we see in life?
  • 00:15: [MUSIC PLAYING] How did life begin?
  • 00:40: So can we approach the question of the origin and the very nature of life from the point of view of physics?
  • 00:49: To understand life, we need to understand entropy.
  • 02:04: That system is life.
  • 02:06: Life has a very low internal entropy because its structure is extremely specific and non-random.
  • 02:54: Not only is life stunningly complex, but that complexity increases over extremely long time scales, in fact, over eons.
  • 03:06: ... trace the development of fossils over the nearly four billion years of life on Earth, we see clear as day the study trend toward greater complexity, ...
  • 04:13: Life acts to reduce its own internal entropy by increasing the entropy of its surroundings.
  • 04:19: ... was first pointed out by Ludwig Boltzmann, who described life as a struggle for entropy, well, more accurately, against entropy or for ...
  • 04:29: Erwin Schrodinger, in his 1944 book, "What is Life," describes life as a process feeding on negative entropy.
  • 04:36: Life absorbs order and it ejects disorder into its surroundings.
  • 04:42: The type of order that life feeds on can be thought of as free energy.
  • 04:54: Another way to say this is that life feeds on energy gradients.
  • 05:03: Life feeds on that flow.
  • 05:05: In fact, the importance of energy gradients to life can help us understand the actual origin of life and its precursors.
  • 05:13: The origin of life on Earth isn't known.
  • 07:37: Molecules better at that process become more abundant, and at some point, they become true self-replicators and eventually, they become life.
  • 07:46: But even life and self-replication might be a very natural part of the same thermodynamic drive to dissipate energy.
  • 08:30: Life is great at dissipating energy, and more generally, it may be that self-replicating systems are the best possible energy dissipators of all.
  • 08:39: This is a new idea proposed by MIT biophysicist Jeremy England, who puts the thermodynamics of life on more solid theoretical grounds.
  • 08:48: ... mathematically that self-replicating molecules and simple single-cell life are extremely good at shedding heat in the act of ...
  • 09:05: And it's not just life that does this.
  • 10:03: Life appears to be just such an eddy.
  • 10:06: In the case of life, the original source of extreme low entropy is the Big Bang itself.
  • 10:10: ... state, little eddies of order, like galaxies, stars, planets, and life naturally ...
  • 10:45: ... OK to be Smart," and PBS "Eons." For the full story of the origin of life, be sure to check out the companion ...

2018-03-07: Should Space be Privatized?

  • 12:13: The first red dwarf will end its life when the universe is something like 100 billion years old.

2018-02-21: The Death of the Sun

  • 00:06: Earth is lifeless.
  • 00:43: Like living things, stars have a life cycle.
  • 00:49: They live their lives fusing hydrogen to helium in their cores, shining bright and stable for as long as that hydrogen lasts.
  • 01:05: The bigger they are, the shorter their lives, and the more sublime their deaths.
  • 01:26: Based on its mass, it's expected to have a lifespan of around 10 billion years.
  • 01:31: ... [INAUDIBLE] life, I mean the period of core hydrogen fusion, when the steady flow of ...
  • 01:43: ... the course of its life, the sun's core is heating, causing the sun to grow and brighten with ...
  • 02:44: This is not the new lease on life that we might hope for.
  • 05:02: But this new lease on life is short.

2018-01-31: Kronos: Devourer Of Worlds

  • 07:36: ... the gradual brightening of the sun and the inevitable extinction of all life on Earth that will result. Or is it ...
  • 07:57: ... luminosity and, as a side benefit, to potentially greatly increase its lifespan. ...

2018-01-24: The End of the Habitable Zone

  • 00:16: And then evaporate the oceans and extinguish all life.
  • 00:27: Hydrogen is fused into helium in the sun's core, producing energy that keeps it shining and keeps the earth warm and hospitable to life.
  • 00:51: This has complex, and for the most part terrible, implications for life.
  • 03:30: In around 600 million years, most photosynthesis will shut down, killing the majority of plant life.
  • 05:27: Yet the geological record tells us that there was plenty of water back then and life appeared quickly.
  • 06:18: Whatever the solution, life has found a way to exist on Earth for at least 3 and 1/2 billion years.
  • 06:24: But life doesn't have such a long stretch ahead of it.
  • 07:40: That doesn't necessarily mean the end of life.
  • 07:52: Life will surely adapt and cling to these last wet patches on or below the surface.
  • 07:58: But ultimately life will vanish in the reverse order that it arrived.
  • 08:03: ... the initial extinction wave from the loss of much of Earth's plant life, other complex multicellular organisms will succumb to heat, perhaps even ...
  • 08:29: But simple prokaryotic life, the very first life to emerge, will hold out until CO2 flatlines, perhaps in less than 2 billion years time.
  • 08:51: So how out some bright sides to distract us from the inevitable end of all life?

2018-01-10: What Do Stars Sound Like?

  • 00:49: ... of the core, the way energy flows to the surface, and even the life span of ...
  • 06:31: ... that our sun is currently around halfway through its 10-billion-year lifespan, which is consistent with age dating of the oldest ...
  • 11:12: A GRB within a few light years would be directly devastating to life.

2017-12-20: Extinction by Gamma-Ray Burst

  • 01:28: Every 100 million years or so, a good deal of Earth's life gets wiped out.
  • 02:34: As many of you know, a supernova is the explosion that follows the catastrophic collapse of a massive star at the end of its life.
  • 07:20: It's a massive star in the last phase of its life, currently blasting off its outer shells into a pinwheel-like nebula.
  • 08:06: Firstly, WR 104 could have up to half a million years of life in it.

2017-11-29: Citizen Science + Zero-Point Challenge Answer

  • 05:08: This all started with the City at Home program, which looks through radio data for signs of signals from intelligent life.

2017-11-22: Suicide Space Robots

  • 01:03: Today, we're going to memorialize the robots that have given their lives in the name of exploration.
  • 03:17: Their designers knew that the solar panels would soon be covered by Martian dust, drastically limiting their lifespan.
  • 05:22: Such vents on Earth's ocean floor host rich living ecosystems and may even have been the origin of life on Earth.
  • 05:41: If those missions find signs of microbial life, we want to be 100% sure that it was not brought there by us.
  • 09:37: It's our way of honoring the many brilliant scientists and engineers who poured their own lives into these ingenious machines.
  • 09:54: ... from the sacrifice of the robots who gave their little silicon lives to blaze the very first paths into outer space ...

2017-11-02: The Vacuum Catastrophe

  • 08:38: ... canceled out their zero point energies, at least enough of them to allow life and astronomers to ...

2017-10-11: Absolute Cold

  • 09:15: Dylan Burris asks, what besides a supermassive black hole lives in the centers of galaxies?

2017-10-04: When Quasars Collide STJC

  • 12:00: ... then that the universe wasn't set up specifically to be able to produce life, then is it not just too lucky that the only universe that exists is a ...
  • 12:20: Then only a small fraction would be capable of supporting life.

2017-09-28: Are the Fundamental Constants Changing?

  • 09:57: ... astrophysical processes that seem to be necessary for the appearance of life are quite sensitive to some fundamental constants, Alpha ...
  • 10:16: It might seem lucky that Alpha is fine tuned for a universe with the warmth of stars, and a rich and complex chemistry-- both essential for life.
  • 10:25: ... in a part of the universe conducive to stars, and to planets, and to life. ...
  • 12:34: Richard, thank you, and may your own fundamental constants remain stable and forever within a range that supports life as we know it.

2017-09-13: Neutron Stars Collide in New LIGO Signal?

  • 01:54: When a massive star ends its life in a supernova explosion, it leaves behind an ultra dense core.
  • 13:56: ... our episode on detecting life by observing extraterrestrial atmospheres, Alex asks whether we can ...

2017-08-24: First Detection of Life

  • 00:12: To detect life on a planet based on measurements by a space probe.
  • 00:17: The experiment was successful, and abundant life was unequivocally confirmed.
  • 00:58: ... aim would be to test if such a probe could positively detect life on a world using only data taken from space, and with as few prior ...
  • 01:14: ... this paper, Sagan et al provides a framework for finding life on other worlds decades before our technology would allow a similar ...
  • 01:29: But first, let's talk about what life on Earth looks like to an observer in space.
  • 01:35: ... easiest-- and so probably the first-- way we'll spot alien life is by its effect on its planet's atmosphere-- in particular, the ...
  • 02:17: Water is essential to life, and oxygen is essential to us, but also an indication of the presence of photosynthesis.
  • 02:31: While some of these molecules are known to arise from life on Earth, their presence isn't enough to confirm life on another planet.
  • 02:39: ... an important and necessary condition for claiming a detection of life is a clear departure from thermodynamic equilibrium-- that is, the ...
  • 02:56: It's definitely not enough to find molecules associated with life-- like water, carbon dioxide, or methane.
  • 03:10: A set of non-equilibrium chemical abundances must be observed that can't possibly be explained without life.
  • 03:18: As Sagan puts it, life is the hypothesis of last resort.
  • 04:42: Alien life might have very different chemistry and so result in other disequilibria.
  • 05:16: Even if we ignore the fact that all Earth life requires it, water is by far the best substance in the universe for brewing up and supporting life.
  • 06:17: Now these wouldn't be considered proof of life on an alien world, but maybe a strong indicator, especially in the presence of atmospheric signatures.
  • 06:41: It proved the existence of life on Earth.
  • 08:16: However, given the planet's blazing 700 degree Celsius surface, it's unlikely that extraterrestrial life would be found.
  • 09:46: Now, there are other reasons to think that the TRAPPIST-1 planets are not ideal for life, but who knows.
  • 09:52: Perhaps our first detection of alien life is only a couple of years away.
  • 10:03: The prospect of there being life on other worlds seems very, very good.
  • 10:14: And if life is common, that evidence will probably be found within our own lifetimes.
  • 10:19: In fact, we may even discover alien life in the next few years.

2017-08-16: Extraterrestrial Superstorms

  • 03:30: A high-pressure core pushes air outwards, depleting the supply of moisture and shortening the storm's life.
  • 07:04: But even with all of this, the Great Red Spot's centuries-long life span is mysterious.
  • 07:56: ... tops and ultimately crash into them to avoid contaminating potentially life-bearing moons like Europa and to peek under the gas giant's cloud ...

2017-08-02: Dark Flow

  • 12:21: Squid, I'm sorry that you and physics broke up, but that's a relationship that leaves its mark on you for life.

2017-07-19: The Real Star Wars

  • 00:33: ... was finally improving the quality of life for a lot of us, science was making incredible bounds, and our sights ...

2017-06-21: Anti-Matter and Quantum Relativity

  • 01:10: Then, in 1926, Erwin Schrodinger wrote down his famous equation, the Schrodinger equation, which breathed life into this emerging model.

2017-05-31: The Fate of the First Stars

  • 03:08: Except that the longest lived stars-- red dwarfs-- have lifespans of trillions of years.
  • 03:25: Star lifespan gets shorter the more massive the spar.
  • 03:53: Before we get to why pop three stars were so large, let's unravel this whole lifespan thing.
  • 05:04: Now, burning through 10 times the fuel at 10,000 times the rate, compared to the sun, means its life is 1,000 times shorter-- only 10 million years.
  • 12:05: Firstly, a trait doesn't have to kill you or save your life to be subject to natural selection.

2017-05-17: Martian Evolution

  • 03:48: Over the years of a human life on Mars, this could be a huge health issue.
  • 05:19: A life on low-G Mars could be at serious risk for early cardiac problems.

2017-05-10: The Great American Eclipse

  • 05:58: ... probably the first time in your life, you see the chromosphere, red from a specific electron transition in the ...
  • 08:41: Astronomical events of this caliber can change your life.

2017-05-03: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson

  • 00:06: ... our video games become more and more lifelike, it's becoming clear that at some point, perhaps soon, our simulations ...
  • 06:06: An average 30 year lifespan gives each of them a billion seconds.
  • 06:52: In other words, it will be capable of simulating the entire mental lives of all humans in history a million times over every single second.
  • 07:04: ... one such computer would generate an insanely large number of lifelong mental experiences that are indistinguishable from the type of mental ...
  • 12:11: Just for now, I strongly recommend that we proceed as though we are real life observers, part of the original space time.

2017-04-26: Are You a Boltzmann Brain?

  • 00:14: Your memory of your entire life also just came into being through a chance arrangement of particles.

2017-03-01: The Treasures of Trappist-1

  • 00:10: A nearby red dwarf star was discovered to have not one, but seven Earth-like planets, and any of them may be capable of supporting life.
  • 01:01: Any one of them could bear liquid water, maybe even life.
  • 06:27: This planetary system probably had a traumatic youth, which may not have been ideal for starting life.
  • 07:01: ... of chemicals indicative of the presence of biological activity-- of life. ...
  • 08:10: Liquid water is just one item on a long list of requirements for life as we know it.
  • 08:38: ... we may have seeing a giant boost in the number of possible homes for life out there in space ...

2017-02-22: The Eye of Sauron Reveals a Forming Solar System!

  • 08:48: But we're more likely to catch loosely bound stellar systems early in their lives.

2017-02-15: Telescopes of Tomorrow

  • 00:36: But Hubble was launched in 1990 and is still working hard over a decade past its original 15-year designed life.

2017-02-02: The Geometry of Causality

  • 12:53: He was in and out of sanitariums throughout his later life.

2017-01-25: Why Quasars are so Awesome

  • 08:06: If life did manage to evolve during this earlier epoch, it would have been quickly obliterated.
  • 09:07: Life finally had a chance.

2016-12-14: Escape The Kugelblitz Challenge

  • 01:35: A black hole forms when the core of a very massive star collapses under its own gravity at the end of a star's life.

2016-12-08: What Happens at the Event Horizon?

  • 03:04: It lives at x=0 on the space axis, but exists through all the times on the graph.
  • 18:34: ... double solution theory, but did work on it intermittently throughout his life and was inspired to return to it by Bohm's publication, even if he ...

2016-11-09: Did Dark Energy Just Disappear?

  • 12:44: So Keivan Stassun's course, "The Life and Death of Stars," gave me some great insights into the nature of the weird corpses left after stars die.
  • 13:47: Anyway, walking around in moon boots and lead bodysuits for your entire life is both unstylish, and it only helps bones and muscles.

2016-11-02: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers

  • 05:52: If you allow that more star types can produce planets with life, then this number just gets smaller.
  • 05:59: Now there are several bio-technological factors that seem important in making technologically-capable life.

2016-10-26: The Many Worlds of the Quantum Multiverse

  • 09:16: Every other possible life path, including those branching in different directions from every decision you ever made, may be just as real.

2016-10-19: The First Humans on Mars

  • 07:10: ... self-sufficient or economically productive enough to justify continued life support from ...
  • 09:13: Several of you asked how to tell the difference between a primordial black hole and a black hole formed when a very massive star ends its life.

2016-10-12: Black Holes from the Dawn of Time

  • 10:57: We recently talked about what life might look like in the ocean of Jupiter's moon Europa.
  • 11:14: Any instrument searching for life will have to be thoroughly sterilized and protected from contamination before reaching its destination.
  • 11:22: But perhaps we'll find life that's different enough to Earth life that there's no possibility that it was from some contamination.
  • 11:50: That's in the Mariana Trench, and there's plenty of life down there, as James Cameron was kind enough to go down and find out for us.
  • 11:58: A few of you wonder why we're so fixated on water as a basis for life.
  • 12:03: For example, Saturn's moon Titan has lakes of liquid methane, and perhaps life could have formed in these.
  • 12:10: However, water has some properties that might make it uniquely awesome for life.
  • 12:36: All of these are important to life as we know it.
  • 12:46: This is important for the stability of water-based life.

2016-10-05: Are We Alone? Galactic Civilization Challenge

  • 00:33: ... in the Milky Way, the number of planets per star that could support life, the fraction of life bearing planets that produce intelligent ...
  • 00:49: And finally, you need to factor in the average lifetime of the typical advanced civilization.
  • 01:36: ... and closer to the formation of the Earth and we see just how quickly life arose ...
  • 01:47: ... a slightly better understanding of abiogenesis, the initial evolution of life and perhaps even the subsequent evolution of intelligence, although ...
  • 02:00: The sociological factors, and in particular, the average lifespan of a technological civilization, are still the subject of wild guesswork.
  • 02:14: We now have a very good idea of how many planets there are in the Milky Way that could potentially support life.
  • 02:30: So 40 billion rocky worlds capable of supporting liquid water, which may be an essential ingredient for life.

2016-09-29: Life on Europa?

  • 00:17: But does that ocean have a life?
  • 00:58: The moon is increasingly looked at as our best chance to find extraterrestrial life in our solar system.
  • 01:05: Today I want to talk about why Europa looks so good for life and exactly what form that life might take.
  • 01:12: At least on Earth, liquid water is absolutely essential for life.
  • 01:16: Every known life form needs at least a little bit.
  • 01:20: Having water on Europa doesn't guarantee life there, but it sure makes it more likely.
  • 02:09: And for reasons we'll get to, that's pretty important for life to have evolved there.
  • 02:37: Well, in general, it's because life needs energy.
  • 03:03: These may be the perfect place for life-- not just to live, but perhaps to have originally evolved.
  • 03:09: In fact, it may be that life on Earth started around its own hydrothermal vents.
  • 03:21: ... idea is the first simple life came into being around so-called black smokers-- volcanic vents in the ...
  • 03:36: Sounds unpleasant, but the regions around these vents are teeming with life-- 10 to 100,000 times the density of organisms compared to the sea floor.
  • 03:57: ... support all sorts of complex life-- forests of tube worms and clusters of clams and mussels that are ...
  • 04:18: Perhaps the dominant life on Europa are also deep-dwelling, sulfur-munching volcanic sea monsters.
  • 04:25: If we believe the iron-sulfur world hypothesis, then deep-sea vents may be where earth life first originated.
  • 04:57: These, in turn, may have resulted in a sort of prebiotic chemical metabolism that enabled evolution into true life.
  • 05:12: ... ocean is in contact with a warm, mineral-rich ocean floor, then perhaps life has found a ...
  • 05:37: However, if life is abundant enough there, then it'll have left its mark on the rest of the ocean-- molecules, isotopic ratios.
  • 06:00: But if life started at those vents, who's to say it stayed there?
  • 06:03: Another promising habitat for Europan life also has an earthly analog-- that's the undersurface of the ice.
  • 06:26: So what does that life look like?
  • 06:53: Life is found throughout earth's oceans.
  • 07:00: And life throughout those depths depends on biological activity at the surface.
  • 09:06: ... plumes-- molecules that tell us even more about the plausibility of life in that ...

2016-09-21: Quantum Entanglement and the Great Bohr-Einstein Debate

  • 12:48: Strofi Kornego and others wonder if life might be the ultimate Von Neumann machine.
  • 12:56: We're on the verge of creating synthetic life ourselves.
  • 13:18: All life on earth pretty clearly descended from the one self-replicating molecule type.

2016-09-14: Self-Replicating Robots and Galactic Domination

  • 01:52: Today I want to argue that even if these points are true, there are reasons to expect a galaxy full of the evidence of past technological life.
  • 05:55: ... home, or terraform the system, or build a Dyson swarm, or annihilate all life-- whatever these aliens are ...
  • 07:36: ... random events that led to technological life dominating the Earth could have happened at least tens, but perhaps ...
  • 07:46: ... if complex life is even remotely common-- say it evolves in one in 1,000 habitable ...
  • 09:24: So how are we here if technological life is so rare?

2016-08-10: How the Quantum Eraser Rewrites the Past

  • 14:07: All surface life is laid waste.

2016-08-03: Can We Survive the Destruction of the Earth? ft. Neal Stephenson

  • 00:22: Most of life on Earth is wiped out on a pretty regular basis.
  • 01:03: But impactors are not the only existential threat to life on Earth.
  • 01:14: ... fossil record, especially in the sudden drops in diversity of fossil sea life in deep cores drilled from the ocean ...

2016-07-06: Juno to Reveal Jupiter's Violent Past

  • 05:20: With these first millions of years of planetary life, it was still embedded in the thick protoplanetary disk.

2016-06-29: Nuclear Physics Challenge

  • 01:15: It has a half life of 0.3 micro-seconds, meaning half of any sample of polonium 212 will have decayed to lead in that time.
  • 01:23: That's also the half life of an individual nucleus.
  • 02:04: ... over the many, many encounters that happen in the 0.3 microsecond half life. ...

2016-06-08: New Fundamental Particle Discovered?? + Challenge Winners!

  • 13:08: Is there something about the tipping point between the dominance of matter versus dark energy that makes the universe more hospitable for life?

2016-05-25: Is an Ice Age Coming?

  • 05:31: ... oceanic sediment cores reveal the changes in ocean floor sea life, whose composition also depends sensitively on ocean temperatures and ...
  • 14:57: We draw energy life bars in our animation sometimes, but the universe doesn't have any hidden energy counter.

2016-05-11: The Cosmic Conspiracy of Dark Energy Challenge Question

  • 04:06: Dark energy has dominated the universe only during the tenure of life on Earth, although its effect has been felt for a bit longer than that.

2016-05-04: Will Starshot's Insterstellar Journey Succeed?

  • 00:02: Breakthrough Starshot plans to send spacecraft to the nearest star within your lifetime.
  • 00:49: To send swarms of light sail driven nanocraft to Alpha Centauri fast enough that we may have close-up images of alien worlds within our lifetimes.
  • 03:21: The Starwisp would accelerate to 10% or so of the speed of light, getting it to alpha [INAUDIBLE] barely within the science team's working life.
  • 06:05: Some type of color spectral sensitivity may even point to life signatures on these planets.

2016-04-06: We Are Star Stuff

  • 01:18: ... is what makes it possible for a universe to have things like planets, life, and minds to try to comprehend it all in the first ...
  • 04:55: Our sun, and in fact every star in the prime of its life on what we call the main sequence, shines by forging hydrogen into helium.
  • 05:36: ... bigger than around eight times the sun's mass, reach the ends of their lives, they become super giants, and their cores become hot enough to continue ...
  • 05:58: At the last moment of a super giant's life, it has onion shells of burning elements.
  • 07:45: And with them, planetary systems and life.
  • 07:56: For more info on the elemental ingredients of life, you have to check out "It's OK to be Smart's" brilliant video.

2016-02-11: LIGO's First Detection of Gravitational Waves!

  • 08:45: Fabio Brady would like to know whether Martian sandstorms are really life threatening.

2016-02-03: Will Mars or Venus Kill You First?

  • 02:00: So let's say you take the six-month trip to begin your new life on Mars.
  • 04:50: Now, the 180-day flight to Mars alone gets you over the recommended lifetime limit of radiation.

2016-01-27: The Origin of Matter and Time

  • 07:28: We're extrapolating the validity of space time diagrams, and these tiny lifelike segments into the quantum realm.

2016-01-13: When Time Breaks Down

  • 00:41: While our memories layer over the course of our lives, and in their ordering, we see the flow of years.

2015-12-09: How to Build a Black Hole

  • 01:13: Let it cook-- not for long because these guys have very short lives.
  • 01:33: ... the last throes of a very massive star's life, increasingly frantic fusion in the interior produces one periodic table ...

2015-11-18: 5 Ways to Stop a Killer Asteroid

  • 02:28: And most life on Earth dies.
  • 08:31: ... of "Space Time." In a recent episode we talked about the origin of life and the Fermi ...
  • 09:30: 794651519, and a number of others, point out that maybe our definition of life is too restrictive.
  • 09:37: Does life have to be chemical?
  • 09:40: Well actually, there's good reason to think that extraterrestrial life might be chemical.
  • 10:00: But even if life can arise in other ways, that just increases the number of lifeforms that we should be able to see.
  • 10:10: Sam Shields asks whether Panspermia is suggesting that life only arose on one planet in the Milky Way before being spread everywhere.
  • 10:30: ... Life would only have to arise once in the galaxy, which allows the initial ...
  • 10:42: The big challenge is getting life-infested rocks to spread through the galaxy.

2015-11-05: Why Haven't We Found Alien Life?

  • 00:04: Recent amazing discoveries have given us more hope than ever that our universe is full of life.
  • 00:43: ... be that there's some sort of great filter that either makes intelligent life extremely rare in the first place or that wipes out, essentially, all ...
  • 01:36: We know of exactly one instance of intelligent life happening, the case of Earth.
  • 01:48: Of course we're going to observe at least one instance of intelligent life happening because we are that one instance.
  • 02:09: ... but for now we need to acknowledge that this selection bias allows that life could be extremely rare, or even ...
  • 02:20: Given that, can we even begin to assess the likelihood of life out there?
  • 02:32: ... Earth certainly required a number of very special conditions to build life and it's hard to know how essential each of these was or how frequently ...
  • 02:42: ... it took to get through each step on the path to building technological life. ...
  • 02:51: ... can crudely summarize the big leaps that lead up to intelligent life as one, assembly of self replicating RNA from organic molecules; two, ...
  • 03:22: ... three steps in that chain combined-- the appearance of true cellular life-- happened faster than any of those later ...
  • 03:36: And in fact, so fast that our galaxy probably should be brimming with at least simple life.
  • 04:03: ... until recently, the earliest known evidence of life dated to roughly 3.5 billion years ago, fossilized blue green algae ...
  • 04:31: But it also suggests that this first step, the genesis of life, is not the great filter.
  • 04:55: ... just recently a zircon was found containing the possible signature of life and dated at 4.1 billion years ago, from before the late heavy ...
  • 05:33: ... other nonbiogenic explanations, but this is extremely suggestive that life was abundant on Earth remarkably soon after it first coalesced from ...
  • 05:51: But either way, it looks like Earth became a slimeball teeming with life in a crazy short amount of time.
  • 06:00: ... given the right conditions the genesis of life happens like that, and two, it didn't happen on Earth-- life was seeded ...
  • 06:55: Questionable, but it would mean that life only needs to evolve once from scratch in any given galaxy.
  • 07:27: However, both suggest that the galaxy should be teeming with slimeball planets filled with life.
  • 07:52: Properly fund NASA and its terrestrial planet finder and we could find extraterrestrial life within 20 years.
  • 07:59: So it's entirely possible that we'll soon discover that the galaxy is filled with life.
  • 08:09: There is a filter, but it's not the genesis of life.
  • 08:17: The first multicellular organism turned up only 600 to 800 million years ago and life as we know it quickly exploded after that.
  • 08:29: No, multicellular life evolved independently dozens of times.
  • 08:46: And speaking of space programs, technological life took a little while longer, but not really so long on the overall scale once we had complex life.
  • 09:19: ... life is common, then of the billions of Earth-like planets in the galaxy, ...
  • 09:48: ... have emerged in the epoch of life in a universe abundant in the rich resources of past supernova ...
  • 09:58: ... strains believability to imagine that life didn't or won't happen elsewhere, but it is possible that we are a very ...
  • 10:12: ... one of the species that will watch and maybe guide as other intelligent life emerges throughout the ...

2015-10-28: Is The Alcubierre Warp Drive Possible?

  • 09:37: ... Un Disclosed, I say, you laugh, but the first evidence of alien life may be the spectroscopic signature of biogenetic atmospheric methane on ...

2015-10-15: 5 REAL Possibilities for Interstellar Travel

  • 00:06: If we wanted it badly enough, interstellar travel could be achievable in our lifetime.
  • 00:54: Our first starship would use technologies achievable in our lifetimes.
  • 02:25: If you want to get to Alpha Cen in a human lifetime, you need to get to 10% the speed of light.
  • 08:45: ... and presumably to a significant fraction of the speed of light in the lifespan of the black ...

2015-09-23: Does Dark Matter BREAK Physics?

  • 04:54: The gas was ripped away from the stars and now lives between the clusters.
  • 09:07: And would this save the monkey;s life or fry it in an eternity of Hawking radiation?

2015-08-19: Do Events Inside Black Holes Happen?

  • 02:31: Even if the ponies and I were immortal, all of us would agree that the monkey's life just doesn't progress past this frozen moment.

2015-07-29: General Relativity & Curved Spacetime Explained!

  • 02:35: ... suppose the ant believes that he lives on an actual plane, and decides to draw an xy grid on a large patch of ...

2015-07-22: SPECIAL ANNOUNCEMENT + Flat Spacetime Geometry Comments

  • 01:45: Well, welcome to my life.

2015-07-08: Curvature Demonstrated + Comments

  • 03:15: ... the same rule as before-- moves in small patches and pretend that he lives on a plane within each patch, and uses a billion small patches as he ...

2015-06-17: How to Signal Aliens

  • 01:48: ... plane alone, where, for reasons I can't get into here, many people think life is more ...

2015-06-03: Is Gravity An Illusion?

  • 11:08: ... affects the atmospheres of planets, and so forth-- the prospect for life, ...
  • 11:35: ... until space travel becomes more accessible and immediate in people's lives. ...

2015-05-20: The Real Meaning of E=mc²

  • 02:35: In everyday life, we just don't notice the discrepancy because it's so small, but it's not zero.
  • 03:59: That's just a billionth of a trillionth of the sun's mass, and only 0.07% of the sun's mass over its entire 10 billion year lifespan.

2015-05-06: Should the First Mars Mission Be All Women?

  • 02:24: It's why NASA allows women only half as much lifetime space flight as it allows men.
  • 07:43: But since I don't have any numbers, I have no way to confirm this. "Interstellar"-- guess what, I haven't seen the movie yet because I have no life.

2015-04-29: What's the Most Realistic Artificial Gravity in Sci-Fi?

  • 03:31: Unfortunately, in real life, even a few RPMs in such a small craft would create a lot of weird effects that "2001" overlooks.

2015-04-22: Are Space and Time An Illusion?

  • 00:35: At first, your brain might resist and hold onto those intuitions for dear life.

2015-03-11: What Will Destroy Planet Earth?

  • 00:00: Lots of unpleasant things from nuclear war to asteroid impacts could destroy life on Earth.

2015-02-25: How Do You Measure the Size of the Universe?

  • 02:32: So over the lifetime of the universe, the birthplace of a beam of light can be carried ridiculously far away by the expanding space dough.
  • 05:50: ... is that colonization on a galactic scale could happen so quickly that if life is really that common, at least one civilization should have already ...

2015-02-18: Is It Irrational to Believe in Aliens?

  • 00:33: With probability statistics, we just need to get a handle on the factors at play in the emergence of intelligent life as we know it.
  • 00:44: Based on recent analyses of exoplanet data, we can now also estimate, without totally guessing, how common planets are that might support life.
  • 00:59: ... to know what percentage of the habitable planets would actually sprout life and then what percentage of those life-sprouting planets would evolve ...
  • 01:26: Anyway, if we get the odds of intelligent life, we're golden.
  • 01:30: Whenever anyone, even a scientist, quotes a number for the "probability" of life arising, it's pretty much a complete guess.
  • 01:40: We have no clue how frequently life sprouts, much less intelligent life, because we have a whopping sample size of one.
  • 02:07: Let's start with a pro aliens argument, that intelligent life should exist.
  • 02:16: So huge that it should compensate even for crazy low odds of intelligent life arising on any one of them.
  • 02:39: If the chances of intelligent life evolving are even lower, well, 200 billion is just the number of habitable planets in our galaxy.
  • 02:53: ... the odds of intelligent life were so insanely low that you couldn't compensate with billions or ...
  • 03:15: The Sagan view then is not that alien life is guaranteed.
  • 03:40: ... there should have been not only enough places for intelligent life to arise, but also enough time for at some of that life to spread around ...
  • 04:54: The punchline is that precisely because we don't see aliens, the odds of intelligent life must be, wait for it, astronomically low.
  • 05:39: ... intelligent alien life never evolves on the billions of possible planets or that intelligent ...
  • 06:04: Maybe the odds of intelligent life arising are pretty decent.
  • 06:07: But the odds of intelligent life going extinct before it can spread into the galaxy are also high.
  • 07:01: D. Moritz found that Sonica Hedgehog lives on a planet with about 5.6 Earth gees, Closer to a planet.
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