We explore the greatest mysteries of the Universe, from the Big Bang, to black holes, dark matter, dark energy, and more, talking with famed cosmologist and author Lawrence Krauss (@TheOriginsPodcast)!

At long last, after 8 billion years of computation, the greatest computer ever developed, Deep Stupor, will reveal its answer to the great question of existence, the cosmos, and what in the semile is going on?

Even an ASCII, an asterisk is just a number.

The Greatest Mysteries of the Universe with cosmologist Lawrence Krauss, Author of The Edge of Knowledge and The Physics of Star Trek.

This week we explore the greatest mysteries of the universe.

Talking about the Big Bang, black holes, dark matter, dark energy, and the nature of time.

Later in the show, we're going to be talking with famed cosmologist and author Lawrence Krauss.

Cosmologists debate what, if anything, might have existed before this explosive event.

The laws of physics needed to model these conditions fall apart as infinities come into play while trying to describe this initial moment of this eruption

For the first 10 millionth of a trillionth of a trillionth of a trillionth of a second after the Big Bang.

All known forces of nature reunited as 1, and the very fabric of space-time itself was subject to the chaotic nature of quantum physics, A bizarre if short-lived start to our universe known as the Plank Epic.

A hundredth of a billionth of a trillionth of a trillionth of a second after the big kickoff, the universe seems to have experienced a strange period known as inflation.

At this time, the universe appears to be expanding at a rate much faster than the speed of light, growing from smaller than an atom to the size of a golf ball almost instantly.

The best-known category of these are stellar-mass black holes formed when a massive star dies and collapses in on itself.

Black holes have such an immense gravitational pull that nothing, not even light, can escape their grasp.

The only exception to this appears to be Hawking radiation, a process which allows some thermal energy to escape the grips of these intergalactic vacuum cleaners.

Matter falling into these regions of space becomes accelerated, pulled, stretched, and blasted with unimaginable amounts of radiation.

However, some information about the interloping body should still remain within the black hole.

What happens to that information, what's going on at the center of a black hole, remains the subject of vigorous debates among some of the greatest minds in the world.

Well, we happen to have 1 of those minds in the studio today.

Well, actually, he himself stayed at home as a stationary body in the past while his image was here in the studio at nearly a simultaneous point in time, creating a 2D representation of his 3D state for you to listen to in my future, which is now your present, and...

Here's Lawrence Krauss talking about what we discover when we dare to journey to the edge of knowledge.

Secrets to how everything around us will, 1 day, end.

Meanwhile, stars, planets, and galaxies dance in an intricate ballet, occasionally giving birth to life.

We are a fledgling species, just beginning to visit other worlds.

We are a way for the universe to understand itself.

The Cosmic Companion strives to bring the universe down to Earth and we depend on your help to make it happen.

For information on subscriptions and ways to donate to this program please visit thecosmiccompanion.net.

This week on The Cosmic Companion, we are delighted to be joined once again by Dr.

He is a theoretical physicist and cosmologist.

He is the author of 1 of my favorite all-time science books, The Physics of Star Trek, and he's here to talk to us about the edge of knowledge and his new show the origins podcast welcome to the show Lawrence

It's great to be back with you again, at least virtually.

It looks like you have cosmic strings behind you.

So a few weeks ago on this show, we were talking with cosmologist Andrew Ponson.

And so I'd like you to start off, if you could, by answering the same question that he started off with, which is, what is cosmology?

You know cosmology is a study of the largest scales of the universe The base to the dynamics of the universe as a whole and not just the parts within it parts within it tend to be the province of astrophysics and then other areas of physics but trying to understand the dynamics of the universe its large-scale structure its origin its evolution and its future and that's basically it and the great thing about the universe is that it was from a particle physicist's perspective is that it was a great particle physics experiment.

And your new book is called is titled At the Edge of Knowledge.

So what are the greatest questions at the edge of knowledge?

Well, I mean, what I wanted to do was follow up in some sense on my last 2 books, the universe nothing, which talked about the potential origin of our universe as we understand it and the revolutions that have taken place in cosmology over the last 50 years.

And then the next 1 was the greatest story we told so far, which talked about the development of what's called the standard model of particle physics, so that describes all the forces that we know, and is the best theoretical picture we have of the universe.

And all of those take us to the point of open questions and I thought it would be a wonderful way to try and move on to talk about indeed the open questions because as I say at the beginning of the book saying I don't know is really the an invitation to discover and and I after some time eventually the book settled down to be 5 main large chapters.

Because the fundamental questions that we really asked about the universe come down to those areas.

And the wonderful thing is that the questions that we all have about ourselves and the universe, you know, how did the universe begin?

When I see green, is it the same color you see, etc.?

They really are the same questions that are at the forefront of modern science.

So it was a wonderful way, hook for me to allow me to talk about those open issues, which of course require me to bring people up to speed in all those areas and to have fun talking about what we know and we don't know.

It's a celebration of discovery, not of ignorance.

And the other thing that's important about it is that while I focus on the things we don't know, and each chapter begins with questions, and I can give some of those questions, That should not be confused with saying we know nothing.

That's all too often when when we say we don't know everything people interpret that to mean we know nothing and that's not true.

We know an incredible amount about the universe and you know when it comes to time big questions you know what is time is is time subjective objective it can you go backwards in time how how did the universe begin?

Can there be many laws of physics and are they different in each universe.

When it comes to matter, I talk about quantum mechanics because quantum mechanics is weird and we still, though most of us think it's a fundamental theory of the universe, not everyone does and it's inconsistent with general relativity.

And so which is the more fundamental theory is something we still have yet to discover.

And then I proceed to the questions of life and consciousness, which may sound like they're beyond the province of a physicist, but in fact, physicists have a long history of being involved in thinking about the origins and evolution of life.

From Erwin Schrodinger's book, what is life that inspired, James Watson to become a geneticist, to, and Max Delbrück's book on, on, on life, which actually inspired.

What inspired Schrodinger and Max Delbrück was a physicist.

He won the Nobel Prize in biology, but for work he did while still a physicist.

So these kind of questions are, and they also get to be the more difficult questions.

The last chapter on consciousness, I happen to think trying to understand consciousness is a lot harder than trying to understand the universe.

So those are some of the open questions and it's an indeed consciousness.

It's not clear we have a good definition of it much less a understanding of it and it may ultimately require us to develop another consciousness, artificial intelligence consciousness.

Maybe that will help us understand what consciousness is.

Anyway, so it touches on basically everything, life, the universe, and everything.

And I thought it might, it's not clear to me my next books will be science books.

So I thought this was a nice sort of, I don't know, that climax is a better, is a way of putting it.

But a nice topping for the books that are written.

And there's probably no better place to start any origin story than with the origin of the universe.

What triggered it and how did it come about?

The answer to all of them is we don't know, which is a great thing.

As I say, we shouldn't be ashamed of it because it is an invitation to discover.

In my book, A Universe of Nothing, focused on what I think is most plausible possibility for our universe itself, that it did begin spontaneously from nothing by the laws of physics and quantum mechanics and general relativity.

That spaces and times can pop into existence when there's no space and time, and a universe with 100 billion galaxies each containing 100 billion stars can pop into existence initially as a universe with 0 total energy.

And it may sound weird when you look around us and see all the stuff out in the universe to think that maybe there's 0 total energy there.

But our best estimate for the total energy of the universe is 0, because gravity has negative energy configurations as well as positive energy ones.

So that's sort of that that was the context of a universe of nothing but a broader question is well that's fine if our universe sprang up from nothing spontaneously But does that beg the question of whether there are other possible universes?

And indeed, the best theory we have about our understanding of the large scale structure of the universe is called inflation, which says that the very earliest moments of our Big Bang, our universe expanded by an unimaginably large amount.

And that happens naturally in almost any particle physics picture of the early universe.

And in that picture in general, as Andre Linde really was the first to emphasize, Inflation never ends.

The expansion of space continues in a rapid space forever.

Local pockets of the, and we call, some people call them pocket universes, can break free of that background expansion and have their own little big bangs and Our universe can be 1.

But other regions may just be having a big bang now or maybe just collapsing.

And the other interesting thing is that as you leave inflation, the manifestations of the laws of physics can be different.

So there could be different laws of physics in each universe.

This picture of a multiverse has changed our whole understanding of what we think a large-scale structure of the universe might be like or the multiverse might be like.

I have done work to try and show that we might actually be able to get empirical evidence, albeit indirect evidence, of the existence of other universes.

And I think that would turn from metaphysics to physics.

And any time you can turn something from metaphysics into physics, that's a good thing.

But in any case, so these universes could go on, that system could go on expanding forever.

There could potentially be an infinite number of such universes.

Can we extrapolate that in the past and say that The expansion has been going on infinitely long in the past.

And the answer is we can't, because in order to understand what happened literally if there wasn't before our universe, we have to have a theory of quantum mechanics and gravity.

And we don't have a theory of quantum mechanics and gravity.

And so to understand that instant of creation, if you want to call it that, you really have to have a theory of quantum gravity.

In the standard theory of general relativity, if you apply it back, or expand the universe back, It tells us that our universe had a finite beginning 13.8 billion years ago.

But it doesn't tell us about anything else, and it doesn't tell us about that nature, that instant of beginning.

There are 2 possibilities, 1 of which is possible, And I know Stephen Hawking used to describe it.

And I think it's very appropriate that there was no time before the beginning of our universe.

Time came into existence when our universe came into existence, as space did, since space and time are tied together.

But it could be that there's a cosmic time in our universe sprang into existence in that sort of time slice of a multi-expanding multiverse.

And there could have been in that sense, in the multiverse, there could be times before at the beginning of our universe.

And speaking of time, there's been a lot of talk lately and especially like even in the popular press about the nature of time.

And if it's even real, What is time, Lawrence?

Well, I mean, time is a thing that determines when you end your interviews, but, you know, some people say time is an illusion, some, even some physicists, And it may be, but I find that particularly useless because it may be an illusion, but if you miss the 515 train home from work, it's not an illusion.

And so the question is, even if it is illusion, how does that come about?

Time, as we know it, is something that basically labels when events happen in space.

Space and time are tied together, especially in general relativity.

So every event happens at a space-time point.

And space and time are really parameters that describe where and when those events happen.

And in general relativity, different observers can have different definitions of time and space, in fact, and different coordinate systems to describe them.

But the laws of physics is independent of those different descriptions.

And so the question, it's like the nature of, there are many illusions that, you know, The classical universe, the desk, this chair I'm sitting on, is an illusion.

It's a classical object, but really, the quantum mechanics is governing its basis.

And the question is, how does that illusion of a classical universe arise?

Some people argue that consciousness is an illusion.

Well, that's again, I may be, but how does that illusion arise?

And so we don't know whether time is an illusion, but we do know a lot about the fact that it is an individual characteristic, that time is different for different observers, that if you're traveling fast with respect to me, your clocks tick at a slow rate.

If you're high up above the Earth, your clocks tick at a slower rate because of gravity.

And all of that sounds esoteric and almost science fiction-like, but it's neither.

As I describe in the book, we use that fact, those esoteric facts every day.

If you use your phone and the GPS on your phone to get anywhere today, you're relying on general relativity because the clocks on the satellites are taking a different rate than the clock on the ground.

And in order to find out where you are, you would need 2 or 3 satellites.

You measure the time it takes for the light signal to go back and forth from the satellite, and you triangulate that and find out where you are.

But if the clocks are out of sync, then your position will be out of sync.

And it turns out, because of general relativity, Primarily, those clocks are ticking at a different rate, and we have to take that into effect explicitly.

The manufacturers and the systems that produce GPS have to take that general relativistic effect into account.

Otherwise, within an hour, you'd be a kilometer away from where you thought you were.

So even those esoteric things have an application in our everyday life.

Of course, the biggest mystery of time is time travel.

Which if you like the physics of Star Trek, I talk about it there because it's sort of the thing that fascinates us most and fascinates science fiction writers the most because of all the wonderful stories you can do about changing the future by going into the past from Star Trek to Back to the Future.

And the answer to is time travel possible is, once again, we don't know.

It looks like it would be very difficult, and it certainly would produce paradoxes, like the grandmother paradox.

What happens if you go back in time and kill your grandmother before you were born, let's say kill your grandmother, well, then your mother would never be born and then you'd never be born.

But if you weren't born, how did you go back in time and kill your grandmother in the first place?

So those kinds of paradoxes would have to be resolvable in a universe that allowed time travel, but we just don't know.

Stephen Hawking used to say that time travel wasn't possible.

Even once off, it created a cocktail party where he invited people from the future to attend and no 1 came in any case.

And we have 2 great mysteries, there are many great mysteries, but 2 of the greatest mysteries about the universe are what is most of the universe?

Dark matter and dark energy both appear to be out there in tremendous quantities but what are they?

Well that's those have been a subject of my research for the last 50 years almost.

I proposed a number of candidates for dark matter, and I'm happy to say I helped propose many of the experiments that are now ongoing to look for dark matter.

Dark matter is most likely a new type of elementary particle.

That's unlike the particles we see on earth.

It may sound like you're just inventing a tooth fairy to explain it.

The point is every theory we have beyond the standard model of particle physics.

Every time we try and extend that model, we come up with the prediction of new particles.

And those new particles have, in many cases, properties that would be perfect to be dark matter and actually could be produced in the early universe in an abundance which would make them dark matter today.

1 has to remember that it's pretty easy for things to be invisible, in a sense.

For every proton in the universe today, there are over a billion photons from the cosmic microwave background behind you and going through my body, this room right now.

1 proton for every billion or so photons.

Well, even though photons are the most observable thing in the universe, we didn't discover the cosmic microwave background until

And so you can imagine other processes producing other particles that are less strongly interacting than photons, that could still easily be invisible.

And in fact, as I say, 1 actually finds such processes in the early universe.

So we're building experiments to look for those things.

And I think it's quite among the known unknowns, the problems I talk about in my new book, I think dark matter is 1 area where we may, if we're lucky, have the answer in the next decade or 2.

Dark energy is a much more difficult problem because it's totally inexplicable.

Why should the dominant energy in the universe reside in empty space?

If you take away all the particles in radiation, space still weighs something.

I mean, when we first proposed that that was the case in our universe in 1995 or so, it seemed crazy, but it was a way to explain the data.

It wasn't until 1998 when the observers got clear evidence that the expansion of the universe is accelerating, which is a consequence of being dominated by the energy of empty space that people began to believe in.

I'm not sure, even when I proposed in 95, that I believed it.

I just probably thought some of the experiments were wrong.

We don't have any idea why that energy is there, what it's made, what it's due to, why it has the value, it's a mystery in fundamental physics.

And that's exciting because it means that, you know, there's a lot to discover.

But because I think it probably relates to our understanding, once again, gravity and quantum mechanics, it's going to be much more difficult not to crack than perhaps discovering the nature of dark matter.

And finally, what's your opinion on, or your thoughts on, how common life may be throughout the cosmos and how long until we find it in 1 form or another?

Yeah that's 1 of the known the central topics in my chapter on life and the answer of course is I don't know once again but But we do know that almost all stars have planetary systems around them, meaning there are perhaps 100 billion solar systems in our galaxy.

We also know that Life evolved on Earth about as soon as the laws of physics allowed.

After the early bombardment of comets and asteroids and Jupiter ate them all up or kicked them in the outer solar system.

Within a few hundred million years, the oldest falls on Earth have been discovered.

So if we're typical in that sense, it would suggest that life formed relatively quickly once the laws of physics allowed it.

What was required was organic materials, water and sunlight.

All of those exist in profusion in the cosmos.

If you think that way, it seems quite likely that there's other life elsewhere in the universe.

Of course, there are very specific circumstances that allow life to evolve on our planet, and those may be rare.

I'm betting that we may find even existence of other genesis of life in our solar system, in the oceans of Europa, or Enceladus most likely.

I wouldn't be surprised if it wasn't there, but I wouldn't be surprised if it wasn't there, but I wouldn't be surprised if it was.

But that's not, of course, intelligent life.

The kind of life that most people care about is the kind that communicates.

That life hasn't been visiting us in little spacecraft, abducting people and subjecting them to weird kinky experiments that hasn't been happening.

It's a long shot, you see, because the universe is very big.

And even with SETI, even with listening, you don't know what to listen to or what to listen for.

And intelligent civilizations, if they exist, could be few and far between.

Judging by the way we're handling things on Earth, it's not clear how long intelligent technological civilizations survive.

So it's an open question, But I think even if it's rare, it's out there.

I just think it's probably, it's not so likely we'll know about it.

And therefore that makes, all of this should make us in some sense feel special.

You know, even If we're unique in the universe, then it's kind of, as Carl Sagan said, a big waste of space.

But it means that we probably should even do more to try and preserve the fortunate circumstance that evolution allowed life to evolve and intelligence to evolve and us to ask these questions.

And even if we're not, we should just say how lucky we are to be around at this moment in the sun.

In 2 or 3000000000 years, the Earth will become uninhabitable, regardless of what we do to it.

And unless we get out more towards where Mars is, which we could do, I suppose, in a billion years.

But we should just take advantage of this incredible accident and the ability to use our brains and to look out and ask questions and continue to ask questions and continue to build experiments and tools that allow us to answer those questions and then have yet more profound questions.

Well, thanks so much for being on the show, Lawrence.

And that was Lawrence Krauss, theoretical physicist and cosmologist and host of the Origins podcast.

Check out his new book, The Edge of Knowledge.

Now, if 1 were to take every star, every bit of interstellar dust, and every molecule of the intergalactic medium stretching across the universe, we'd still be holding only about 5% of what seems to be out there.

The other 95% of everything is made up from a mixture of 27% dark matter and 68% dark energy.

These are questions that scientists are currently struggling to understand.

Now, galaxies and groups of galaxies only hold together because of what appears to be gargantuan clumps of invisible gravitational centers.

Stars and galaxies move exactly like there's far more matter around them than everything we can see.

But Where the matter should be, there is apparently nothing.

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The Greatest Mysteries of the Universe with Lawrence Krauss