October 2, 2025 • 40 mins
Explores the ultimate fate of the universe, drawing on contemporary cosmological theories. It investigates various scenarios for the universe's end, from a "heat death" of perpetual expansion and cooling, to a "big crunch" of eventual collapse. Davies discusses the big-bang theory as the universe's origin and how initial conditions influence its demise. The text also examines threats to humanity and Earth, like cometary impacts and solar expansion, and speculates on the potential for technological survival and adaptation in the face of cosmic timescales and physical laws, including concepts like black holes and proton decay.
You can listen and download our episodes for free on more than 10 different platforms:
https://linktr.ee/book_shelter
Get the Book now from Amazon:
https://www.amazon.com/Last-Three-Minutes-Conjecture-Ultimate/dp/0465048927?&linkCode=ll1&tag=cvthunderx-20&linkId=bc3cf3725baebe94bcf79eff23652d08&language=en_US&ref_=as_li_ss_tl
You can listen and download our episodes for free on more than 10 different platforms:
https://linktr.ee/book_shelter
Get the Book now from Amazon:
https://www.amazon.com/Last-Three-Minutes-Conjecture-Ultimate/dp/0465048927?&linkCode=ll1&tag=cvthunderx-20&linkId=bc3cf3725baebe94bcf79eff23652d08&language=en_US&ref_=as_li_ss_tl
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Will the universe end? And if so, how I mean?
Will it be some sudden fiery cataclysm engulfing everything we
know or maybe a slow, quiet fade into oblivion like
a whimper, stretching over unimaginable time. Today we're really diving
into precisely these well profound, mind bending questions. We're using
Paul Davies's fantastic book the last three minutes conjectures about
(00:24):
the ultimate fate of the universe as our guide.
Speaker 2 (00:27):
Welcome to the deep dive. And yeah, this isn't just
about colsmic destruction, not really. It's more like a grand
story of the universe's birth. It's you know, vibrant life
and its many potential deaths. Right, we'll explore the scientific
predictions from the local threats right here on Earth to
the truly universal ones, and we'll see why understanding the
beginning is absolutely key to grasping the end.
Speaker 1 (00:49):
Okay, sounds like a journey, so get ready for time
scales that just challenge the imagination in physics, that'll stretch
your mind. Definitely. All right, let's maybe unpack this with
a bang. Literally. Davies kicks off our story close to home,
painting this vivid, almost cinematic picture of Doom's day on Earth.
Speaker 2 (01:04):
Yeah, it's quite the scene.
Speaker 1 (01:06):
Imagine this August twenty first, twenty one to twenty six.
There's this trillion ton comet Swift Tuttle hurtling towards us
at forty thousand miles prout.
Speaker 2 (01:17):
That's incredibly fast.
Speaker 1 (01:18):
It is. He describes this fiery descent, a thousand cubic
miles of air blasted aside than this searing finger of flame,
wider than a city just lancing the earth. Wow, the
force is catastrophic. I think massive earthquakes, tsunamis, trillions of
tons of rock vaporized, plunging the whole world into darkness.
Speaker 2 (01:37):
It's a truly chilling scenario. And you know, fortunately the
revised calculation shows Swift Tuttle will actually miss us in
twenty one to twenty five.
Speaker 1 (01:44):
Oh good.
Speaker 2 (01:44):
That's a relief, it is, but it really serves as
a stark reminder of a very real, recurring danger. There
are something like ten thousand objects asteroids, commets, maybe half
a kilometer or more across that cross Earth's orbit. Ten thousand, yeah,
and any one of them could cause more damage than
all new clear weapons.
Speaker 1 (02:00):
Combined.
Speaker 2 (02:01):
These kinds of impacts, well, they happen on average every
few million years, like the one that took up the dinosaurs,
you know, sixty five million years ago.
Speaker 1 (02:07):
So okay, a direct impact is terrifying, obviously, but Davies
also suggest we're vulnerable to more subtle cosmic nudges too.
Beyond those direct hits. What are some of those other dangers,
maybe some of the more exotic ones.
Speaker 2 (02:21):
That's right, Well, Jupiter, for instance, it's huge gravity usually
protects us, acting like a cosmic vacuum cleaner in a way, right,
but sometimes it can also slingshot asteroids our way. Then
you've got passing stars that might nudge comets out of
the distant ort cloud sending them towards us the ort
cloud way out there exactly. And then there are the slower,
maybe more insidious threats, things like ecological degradation, climate change,
(02:44):
or even just a slight but sustained variation in the
sum's heat.
Speaker 1 (02:49):
Output, things that unfold over millennia.
Speaker 2 (02:51):
Precisely, which gives humanity a chance to adapt if we're
clever enough, if we can manage it. But ultimately, yeah,
our planet's fate is just inextricably intense with the fate
of the stars and really the whole universe, and this
kind of.
Speaker 1 (03:03):
Leads us naturally to the universe's own inevitable decline. Davies
introduces Herman von Helmholtz's well profoundly depressing prediction from way
back in eighteen fifty six, The universe is dying.
Speaker 2 (03:17):
Yeah, that's a heavy one, and it comes from the
second law of thermodynamics.
Speaker 1 (03:21):
Okay refreshes on that.
Speaker 2 (03:22):
It essentially says that heat always slows from hot to cold,
and this quantity called entropy, it always increases things tend
towards the disorder.
Speaker 1 (03:31):
Basically like a melting ice cube or a cooling cup
of coffee.
Speaker 2 (03:34):
Exactly, heat moves from hotter to colder irreversibly. You can't
really put the heat back easily, and the Sun just
endlessly pouring heat and light out into cold space. That's
a spectacularly irreversible process.
Speaker 1 (03:47):
So it's constantly increasing the universe's total entropy.
Speaker 2 (03:50):
Right, And the ultimate destination of this whole process is
something called heat death. It's a state of maximum entropy
where the entire universe reaches a uniform sort of luke
warm temperature.
Speaker 1 (04:00):
And nothing more can happen pretty much.
Speaker 2 (04:03):
No useful energy transfer can ever happen. Again, nothing of
well value in a physics sense can occur.
Speaker 1 (04:09):
Wow, that sounds incredibly passive for something so vast. Is
there any theoretical loophole? Or is this really it the
universe's ultimate unshakable fate.
Speaker 2 (04:20):
Well, the physics behind it is pretty stark. It certainly
led to some deep philosophical despair for people like Bertran
Russell shaped his atheism even but paradoxically, this very prediction
gives us a surprising clue about the universe's beginning. See,
if the universe is running down at a finite.
Speaker 1 (04:36):
Rate, then it can have existed forever.
Speaker 2 (04:38):
Exactly, it must have had a finite beginning.
Speaker 1 (04:40):
That idea of a finite beginning is really really mind bending.
It even helps solve what seems like a simple observation
but is actually a deep cosmic mystery. Olver's paradox, Why
is the night sky dark? Ah?
Speaker 2 (04:53):
Yeah, Older's paradox? It asks that simple question, why is
the sky dark at night? Sounds trivial, right right, But
if the universe were truly infinite, eternally old, and just
uniformly filled with stars, then literally every single line of
sight you could draw should eventually hit a.
Speaker 1 (05:09):
Star, making the night sky infinitely bright like the surface.
Speaker 2 (05:14):
Of the Sun exactly. The resolution is absolutely central to
modern cosmology. The universe has a finite age, maybe ten
twenty billion years, and crucially, it's expanding.
Speaker 1 (05:27):
So we can only see stars within a certain distance
the observable universe.
Speaker 2 (05:31):
Precisely, there hasn't been enough time for all the starlight
from everywhere to reach us, nor for the universe to
reach that state of thermodynamic equilibrium, that heat death state.
So yeah, this solidifies the idea the universe had a
beginning and it's definitely heading towards an.
Speaker 1 (05:47):
End, so okay. To truly understand the end, Davies argues,
we absolutely have to look to the beginning. And scientists
pretty much unanimously agree the cosmos originated what ten to
twenty billion years ago in the Big Bang.
Speaker 2 (06:00):
It's the consensus. Yeah, And the most direct evidence came
from Edwin Hubble back in the twenties his discovery of
the red shift of distant galaxies showing.
Speaker 1 (06:08):
The light waves are being stretched out right.
Speaker 2 (06:09):
Which tells us the universe is expanding, and crucially It's
not just galaxies flying apart through space, it's that space
itself is stretching between them, carrying them along like buttons
sewn onto an elastic string being stretched.
Speaker 1 (06:21):
That stretching of space. That's a key idea form Einstein's
general relativity, isn't it?
Speaker 2 (06:26):
It is? And if you run that cosmic movie backward,
tracing the expansion back in time, it suggests the universe
started with well zero size, infinite density, infinite expansion rate.
The Big Bang singularity.
Speaker 1 (06:38):
An event that wasn't an explosion.
Speaker 2 (06:40):
In space, but the origin of space, time, matter, and
energy itself. As Davies puts it quite starkly, there was
no before Wow.
Speaker 1 (06:48):
Then in nineteen sixty five came this incredible discovery, the
cosmic afterglow, the cosmic microwave background radiation, the CMBE Yeah.
Speaker 2 (06:57):
The leftover heat from the Big Bang itself. Today it
bathes the entire universe at about three degrees above absolute zero,
just a faint microwave hiss everywhere you look.
Speaker 1 (07:06):
And it's near perfect uniformity. But with these tiny little
temperature ripples discovered later by the Kobe.
Speaker 2 (07:11):
Satellite, those ripples are key. They show the early universe
was incredibly hot, dense, and remarkably smooth, but not perfectly smooth.
Those tiny ripples were the seeds of future galaxies and
cosmic structures.
Speaker 1 (07:23):
And there's more evidence. Right the chemical composition.
Speaker 2 (07:26):
Absolutely the universe is about seventy five percent hydrogen and
twenty five percent helium, with it just trace amounts of
other light elements. This matches perfectly with the predictions of
nuclear reactions happening in the first three minutes after the
Big Bang.
Speaker 1 (07:39):
So the evidence for the Big Bang is strong, But
you mentioned questions remained, like why was it so uniform?
Where did those ripples actually come from exactly?
Speaker 2 (07:47):
The standard Big Bang model didn't quite explain why it
was so smooth, or why the expansion rate seems so
finely tuned. That's where the idea of inflation comes in.
It's a central part of what Davies calls the new
cosmology inflation.
Speaker 1 (08:00):
Okay, what's the core idea there.
Speaker 2 (08:02):
The idea, and it's pretty audacious, is that in the
very first tiny fraction of a second, like ten to
the minus thirty five seconds, the universe underwent this brief
but incredibly rapid exponential expansion much much faster than the
later expansion.
Speaker 1 (08:17):
Like hitting a cosmic accelerator pedal sort of.
Speaker 2 (08:19):
Yeah, powered by a peculiar unstable energy state called a
false vacuum. Think of it as a supercharged but temporary
kind of emptiness that exerted a sort of anti gravity
or negative pressure, driving this hyper expansion.
Speaker 1 (08:32):
And this inflation solves those problems.
Speaker 2 (08:34):
It does rather elegantly. This enormous rapid stretching would naturally
smooth out any initial bumps or irregularities, explaining the observed uniformity.
It also explains why the universe is so vast and
those tiny quantum fluctuations happening during inflation.
Speaker 1 (08:49):
It gets stretched out too.
Speaker 2 (08:51):
Exactly, They get blown up to cosmic scales, providing the
seeds for the ripples we see in the CMB, which
eventually grew into galaxies. It's mine bending. The basic structure
of the universe might have been set in just ten
thirty two seconds.
Speaker 1 (09:04):
Incredible, So, as Davey says, the beginning and the end
of the universe are deeply intertwined.
Speaker 2 (09:09):
Absolutely, you can't really understand one without the other.
Speaker 1 (09:12):
Okay, let's zoom back in now, from the whole cosmos
to individual cosmic drama the birth and Death of stars.
Davis calls it stardom. He starts with supernova nineteen eighty seven.
Speaker 2 (09:22):
A ah yes, nineteen eighty seven a a huge event
for astronomers, the first supernova visible to the naked eye
since sixteen oh four.
Speaker 1 (09:30):
But the really surprising part Davy's notes came hours before
the visible light arrived. Deep underground. In detectors in Japan
and Ohio.
Speaker 2 (09:38):
They picked up bursts of neutrinos. Wolfgang Polly's spinning goes,
these incredibly elusive particles with almost no mass, no charge,
barely interacting with anything.
Speaker 1 (09:49):
And detecting those neutrinos at the same time as the supernova.
That was huge, right.
Speaker 2 (09:53):
It was crucial confirmation of supernova theory. It showed what
happens inside these massive stars. They fuse lighter el elements
into heavier ones, hydrogen to helium, helium to carbon, and
so on up the.
Speaker 1 (10:04):
Periodic table until they hit iron.
Speaker 2 (10:06):
Exactly fusin iron costs energy, it doesn't release it, so
the star's core suddenly loses its energy source. It can
no longer support itself against its own immense gravity, and
it collapses catastrophically. It implodes, bounces off the super dense core,
creating a massive shock wave, and that tremendous burst of
neutrinos we detected. Then the outer layers explode outwards with
(10:27):
the light intensity of maybe ten billion suns.
Speaker 1 (10:31):
Wow, and these incredibly violent deaths. Yeah, they aren't just destructive,
are they? Note at all?
Speaker 2 (10:36):
They're fundamentally creative. Supernovas are the cosmic forges that create
all the heavy elements heavier than iron, things like gold, lead, uranium,
and then they scatter this precious stuff across space.
Speaker 1 (10:48):
So Davies reminds us the very stuff of our bodies
is composed of the nuclear ash of long dead stars.
Speaker 2 (10:55):
It's quite poetic, but literally true. And what's left behind
after the explos either an incredibly dense neutron star, maybe
the size of a city but with more mass than
the Sun, or for even more massive stellar cores, a
black hole.
Speaker 1 (11:09):
But our own Sun. It's not massive enough for that
kind of fireworks, right correct.
Speaker 2 (11:15):
Our Sun will have a gentler, though still pretty dramatic
for us demise. It's about halfway through its ten billion
year hydrogen burning life. Now, in another five billion years
or so, it'll run out of hydrogen in its core
and start fusing hydrogen in a shell around the core,
and that makes it swell up dramatically. It'll become a
red giant, swelling perhaps hundreds of times its current size,
(11:35):
likely engulfing mercury Venus and almost certainly Earth.
Speaker 1 (11:39):
So Earth gets incinerated.
Speaker 2 (11:40):
Yeah, Unfortunately, Then, after maybe shedding its outer layers as
a planetary nebula, the Sun's core will shrink down into
a white dwarf. A white dwarf, it's a small, incredibly
dense cinder, about the size of Earth but containing maybe
half the Sun's original mass. It's very hot initially, but
it has no more fuel to burn, so it just
slowly cools down over trillions of years, eventually solidifying maybe
(12:04):
into a crystal structure, and fading into blackness, A black dwarf.
Speaker 1 (12:08):
A quiet end for stars like ours, Yeah, but it's
still an end, a sort of prelude to this wider
cosmic nightfall.
Speaker 2 (12:15):
You mentioned exactly.
Speaker 1 (12:16):
So our own Sun becomes a cold, dark ember. But
what happens much much later, when all the stars across
the entire cosmos have finally dimmed and died out. That's
its chilling prospect Davies calls nightfall.
Speaker 2 (12:29):
Right, the universe currently lit up by nuclear fusion and
stars will eventually exhaust this primary energy source. New star
formation will basically cease as the intercellar gas gets used
up or locked away. The universe just gets inexorably dimmer.
The era of light, as Davies puts, it, will be
over forever.
Speaker 1 (12:45):
But the story doesn't end just when the lights go out,
does it? Because gravity is still there.
Speaker 2 (12:50):
Gravity is always there. Even though it's the weakest fundamental
force on cosmic scales and over cosmic time scales, it
remains utterly dominant. Long after nuclear energy is gone. Gravity
continues to shape the universe's.
Speaker 1 (13:02):
Fate, and gravity is linked to black holes, which you
mentioned are the remnants of massive stars. These seem to
hold immense power.
Speaker 2 (13:09):
They really do. Black holes represent gravity's ultimate triumph, crushing
matter essentially to a point of infinite density, warping space
time around them intensely. Davies uses this thought experiment. Imagine
lowering a weight slowly towards a black hole on a pulley. Okay,
in principle, as the weight falls in, you could extract
(13:31):
almost all of its rest mass energy EMC squared. It
does work. That's potentially over one hundred times more energy
than you get from nuclear fusion.
Speaker 1 (13:39):
Wow. Is there any real world evidence for that kind
of power?
Speaker 2 (13:42):
Absolutely? We see it in systems like Signus X one.
It's a binary star system where we see a visible
star orbiting something invisible, but that invisible companion is pouring
out intense X rays, which comes from matter being pulled
off the visible star heating up to millions of degrees
as it spirals into the intense gravity of the unseen companion,
which has to be a black hole. We also see
(14:04):
super massive black holes at the centers of most galaxies,
including our own Milky Ways Sagittarius A. They power incredibly
energetic phenomena like quasars and jets.
Speaker 1 (14:14):
And these powerful objects. Yeah, they don't just sit still either. Right.
You mentioned gravity waves, right.
Speaker 2 (14:19):
Einstein's theory predicted that accelerating massive objects should create ripples
in the fabric of space time itself, gravitational waves. We've
now directly detected these famously from merging black holes and
also merging neutron stars.
Speaker 1 (14:32):
Like those binary neutron stars in Akola exactly.
Speaker 2 (14:35):
We observe them slowly spiraling closer together over decades, losing
energy precisely as predicted by emitting gravitational waves before they
finally merged. When black holes merge, they can release a
truly staggering amount of energy, potentially up to two thirds
of their total mass energy purely as gravitational waves.
Speaker 1 (14:54):
That's immense energy, and falling into one Detes describes a
two doesn'ty spaghetification does.
Speaker 2 (15:00):
If you are unlucky enough to fall into a black hole,
you'd first cross the event horizon, the point of no
return where even light can't escape inside, the tidal forces
become extreme. The gravity at your feet would be so
much stronger than at your head that you'd be stretched
out like spaghetti while simultaneously being squeezed from the sides. Ultimately,
(15:21):
you'd reach the central space time singularity, a point where
our current understanding of physics breaks down. Gravity becomes infinite,
and space and time, at least for you, would simply end.
Speaker 1 (15:32):
So Ultimately, gravity's cumulative action over these vast time scales
is what determines the universe's final fate.
Speaker 2 (15:39):
That's the core idea.
Speaker 1 (15:41):
Which brings us right back to that great cosmic question,
will the universe expand forever, cooling and dimming, or will
gravity eventually win out, halting the expansion and pulling everything
back together in a big crunch.
Speaker 2 (15:52):
And the answer hinges quite literally, on how much the
universe weighs its overall density of matter and energy.
Speaker 1 (15:59):
How do we even begin to weigh the universe?
Speaker 2 (16:01):
Yeah, well it's not easy. If you just count up
all the visible stuff, stars, galaxies, gas clouds, the total
mass seems too low. It suggests the universe's gravity isn't
strong enough to stop the expansion. It would expand forever.
Speaker 1 (16:15):
There's a catch, isn't there? Dark matter?
Speaker 2 (16:17):
The big catch? Most of the universes matter, it turns out,
is completely unseen. It doesn't shine, it doesn't absorb light,
it doesn't reflect light. It's dark.
Speaker 1 (16:26):
So what could this dark matter be?
Speaker 2 (16:27):
Well, there are several candidates. One possibility is neutrinos. We
know there are vast numbers of them left over from
the Big Bang, maybe a billion for every proton or neutron.
Speaker 1 (16:37):
Those ghostly particles again.
Speaker 2 (16:39):
Yeah, and while they were originally thought to be massless,
we now know they have a tiny, tiny mass. It's
not much individually, but there are so many of them.
That collectively they could potentially outweigh all the stars combine.
Supernova nineteen eighty seven A actually helped put some limits
on their mass.
Speaker 1 (16:57):
Okay, what else?
Speaker 2 (16:57):
Then? There are more exotic hypothetic particles, often lumped together
as WIMPs, weakly interacting massive particles, things predicted by theories
beyond the standard model of particle physics, like gravitinos or fatinos.
There are incredibly ambitious experiments deep underground trying to detect
the very faint bang one of these might make if
(17:19):
it occasionally bumps into an atomic nucleus, and a super
cooled crystal detector.
Speaker 1 (17:24):
Searching for ghosts in the dark. Basically, what's the actual
evidence that this stuff exists? Though?
Speaker 2 (17:29):
If we can't see it directly, the astronomical evidence is
really overwhelming. Actually, it comes from multiple directions. One classic
example is galaxy rotation.
Speaker 1 (17:37):
Curves, how stars move within galaxies.
Speaker 2 (17:40):
Exactly, you'd expect stars farther out from the center of
a galaxy to orbit slower, just like planets farther from
the Sun orbit slower. But that's not what we see.
Stars in the outer parts of galaxies orbit at roughly
the same speed as stars closer in, which means it
means there must be a huge amount of unseen mass
extending far beyond the visit disc of the galaxy, creating
(18:02):
extra gravity to hold on to those fast moving outer stars.
This invisible dark matter halo seems to contain maybe ten
to one hundred times more mass than all the luminous
matter the stars and gas we can see.
Speaker 1 (18:14):
Wow, ten to one hundred times more.
Speaker 2 (18:16):
Yeah, And we see similar evidence in clusters of galaxies.
The individual galaxies within large clusters like the Coma cluster
are moving around much too fast to stay gravitationally bond
together unless there's hundreds of times more mass present than
what we see in the galaxies themselves.
Speaker 1 (18:33):
So the clusters should have flown apart long ago if
it wasn't for dark matter holding them together.
Speaker 2 (18:37):
Precisely, even the large scale structure of the universe, the
way galaxies are arranged in these vast filaments and sheets
with voids in between, this sort of cosmic web requires
the extra gravitational pull of dark matter to form over
the age of the universe.
Speaker 1 (18:51):
Okay, so dark matter seems to outweigh normal matter by
at least ten to one, maybe much more. Does that
mean the universe will eventually collapse. Does it tip the scales?
Speaker 2 (18:59):
That's the t trillion dollar question. It definitely adds a
lot more weight, but whether it's enough to cause a
big crunch is still uncertain. Interestingly, the theory of inflation
that rapid expansion early on actually makes a prediction.
Speaker 1 (19:12):
Here, Oh, what does inflation predict about the universe's density?
Speaker 2 (19:17):
It predicts that the universe's overall density should be extremely
close to the critical density, the exact value needed to
eventually halt the expansion, but just barely so. The universe
might be balanced.
Speaker 1 (19:29):
On a knife edge, meaning if it does collapse.
Speaker 2 (19:32):
It will happen in the very very very distant future.
We're talking trillions upon trillions of years from now, maybe
so far off that the difference between eternal expansion and
eventual collapse is practically undetectable for us now.
Speaker 1 (19:45):
So the universe faces these two main paths, these two
potential ultimate fates eternal expansion leading to a cold, dark
whimper or eventual collapse into a hot, fiery big crunch,
and each one has starkly different implications for the ultra
long term future.
Speaker 2 (20:00):
Exactly two very different endgames.
Speaker 1 (20:02):
Let's explore that first possibility, then the whimper scenario. If
the universe expands forever, Davies paints a picture of a
bleak infinity. He stresses that infinity is qualitatively different from
supendously huge.
Speaker 2 (20:17):
Yeah, that's a key point. In an infinite amount of time,
anything that can happen, no matter how improbable, will eventually happen.
Speaker 1 (20:24):
So imagine the universe, say a trillion trillion years from now,
what does it look like?
Speaker 2 (20:28):
Utterly dark, incredibly diluted, filled only with the cold cinders
of stars, black dwarfs, neutrons, stars, and of course black holes,
all drifting ever farther apart as space continues to expand.
Speaker 1 (20:40):
But gravity isn't completely done yet. Even then, not quite.
Speaker 2 (20:44):
Even in this incredibly dispersed state, gravity still operates. Gravitational
wave emission, although incredibly feeble from orbiting dead stars, will
continue over unimaginable timescales.
Speaker 1 (20:55):
Causing them to spiral into each other.
Speaker 2 (20:57):
Eventually, yes, dead stars will slow spiral into each other
and merge, or they'll fall into the supermassive black holes
at the centers of what used to be galaxies. Also,
gravitational interactions like near misses between these stellar remnants will
act like slingshots, ejecting most objects out of their original
clusters into the vast emptiness of intergalactic space.
Speaker 1 (21:18):
And even the black holes, right, they don't last forever either.
You mentioned Hawking radiation, right.
Speaker 2 (21:24):
Stephen Hawking's ground broking discovery in the nineteen seventies was
that black holes aren't truly black due to quantum effects
near the event horizon, involving pairs of virtual particles popping
into existence. Black holes actually emit a faint thermal glow,
now called Hawking radiation, so they slowly evaporate, very very slowly.
The smaller the black hole, the hotter it is, and
(21:45):
the faster it evaporates. A solar mass black hole would
take something like one hundred and sixty six years to
evaporate completely. Larger ones like the supermassive ones and galactic
centers take vastly longer, maybe ten hundred and ninety three
years or more, But eventually even they should disappear in
a final burst of energy.
Speaker 1 (22:02):
Tend to the power of ninety three years. That's just
impossible to grasp. But the disintegration doesn't stop there, does it.
What about ordinary matter itself.
Speaker 2 (22:10):
Yeah, this is where it gets even weirder. Even things
we think of as perfectly stable, like protons or even
the structure of atoms, might be unstable over these truly
immense time scales. Freeman Dyson pointed out this bizarre quantum
effect called quantum tunneling. Got It's a quantum mechanical phenomenon
where a particle can, with a very small probability, pass
(22:32):
through an energy barrier, even if it doesn't technically have
enough energy to go over it. Over incredibly long time spans,
these tiny probabilities add up. Dyson calculated that even something
like a diamond, seemingly eternal, would eventually, after maybe ten thousand,
sixty five years, slowly rearranges atoms via tunneling into a
more stable spherical configuration like a featureless bead.
Speaker 1 (22:53):
Diamonds turn into beads okay, and protons the very building
blocks of atoms.
Speaker 2 (22:58):
Well. Many modern physics theories be Beyon the standard model
called gran unified theories or GUTS, predict that protons themselves
might not be truly stable. They might decay, perhaps into
lighter particles like a positron and a pion, over incredibly
long time scales maybe ten thousand and thirty two years,
or longer.
Speaker 1 (23:16):
Ten to the thirty two years. So if protons.
Speaker 2 (23:18):
Decay, then all ordinary matter, planets, dead stars, everything made
of atoms would eventually just evaporate into a bath of
radiation and lighter particles. Experiments are actually running right now,
deep underground in places like Commioca looking for the telltale
flashes of light from a decaying proton, but so far
none have been definitively seen, meaning the lifetime is at
(23:39):
least that long, if not infinite.
Speaker 1 (23:40):
So after proton decay, after black hole evaporation, what's left
the ultimate.
Speaker 2 (23:46):
Residue an inconceivably dilute, cold, dark soup mostly photons and
neutrinos from all the decay processes, plus maybe a dwindling
smattering of electrons and positrons, all drifting ever farther apart
in the eternally expanding space, just leaks sterility. This is
the modern conception of the heat death.
Speaker 1 (24:03):
Bleak, indeed, which brings us back to that human question.
Even in this desolate, far flung future, could life or
perhaps our distant descendants possibly persist, Could consciousness somehow survive?
Speaker 2 (24:16):
That is the ultimate question in this scenario, isn't it It
certainly seems chilling, almost futile. It makes you circle back
to the bertrand Russell's despair. If everything eventually fades to nothingness,
what's the point exactly?
Speaker 1 (24:28):
How does Davies tackle that? Does he offer any hope
any way for humanity or perhaps intelligence itself, to achieve
some kind of immortality, maybe what he calls life in
the slow lane?
Speaker 2 (24:38):
He does challenge that despair. He first points out humanity's
potential for long term survival and adaptation, even on cosmic scales.
He envisions our descendants potentially colonizing the galaxy through planet hopping,
maybe using genetically engineered being suited for different environments, or
perhaps arcships carrying frozen embryos. This could happen in maybe
just thirty million years or so.
Speaker 1 (25:00):
Thirty million years sounds long to us, but it's a blinking.
Speaker 2 (25:02):
Cosmic time, right, and he speculates that future beings might
not even resemble us physically. They could be genetically modified
or even post biological entities, cyborg sophisticated organic computers, maybe
vast neural networks inhabiting space itself. The focus shifts from
preserving are exact physical form to preserving the human spirit, culture,
(25:25):
knowledge values thought itself.
Speaker 1 (25:27):
But how do you preserve thought when the universe is
running down, energy is becoming scarce, and everything is cooling
towards absolute zero. That's where Freeman Dyson's idea comes in, right.
Speaker 2 (25:37):
Yes, Dyson's really fascinating scenario for achieving subjective immortality in
an eternally expanding, cooling universe. The key problem is that
any thought process, any computation, requires energy and necessarily dissipate
some of that energy as waste heat, increasing entropy. You
can't think for free thermodynamically.
Speaker 1 (25:55):
Speaking, so how do you heat around that?
Speaker 2 (25:57):
Dyson's ingenious idea is that sentient beings could a dapt
by progressively slowing down their metabolic rate their thinking processes.
As the universe cools, they would cool down with it,
entering periods of hibernation for longer and longer.
Speaker 1 (26:08):
Durations, hybridating for millions, billions, trillions of years exactly.
Speaker 2 (26:13):
This allows them to conserve their finite energy resources, letting
energies slowly accumulate between brief periods of activity, and giving
the waste heat plenty of time to dissipate into the
increasingly cold background. By doing this, living it down, as
Davies puts it, they could potentially stretch a finite amount
of energy over an infinite amount of subjective time. They
(26:35):
could experience an infinite number of thoughts.
Speaker 1 (26:37):
Infinite thoughts with finite energy by slowing down infinitely.
Speaker 2 (26:43):
That's the concept. There are debates about whether you could
have an infinite number of different thoughts, which might depend
on whether computation is fundamentally digital or analog, but the
principle is there. It suggests a way. However, desperate for
consciousness to persist indefinitely, a struggle against the dying of
the light. It offers a sliver of hope against the
bleakness if the universe expands forever.
Speaker 1 (27:04):
A desperate hope maybe. But what about the other fork
in the road. What if the universe's ultimate fate isn't
that slow fade, but a fiery end the Big Crunch scenario.
If there is enough dark matter, enough total.
Speaker 2 (27:16):
Density, then gravity eventually wins. It halts the cosmic expansion,
perhaps trillions of years from now, and begins to pull
everything back together.
Speaker 1 (27:25):
The universe starts contracting. What would that look like.
Speaker 2 (27:28):
Initially, it would be the expansion in reverse, but very
slow at first. Galaxies would stop receding from each other
and start falling back together. The cosmic microwave background radiation,
which has been cooling ever since the Big Bang. As
space six panded, it.
Speaker 1 (27:42):
Would start heat up again. As space contracts.
Speaker 2 (27:44):
Exactly, it gets blue shifted instead of red shifted. As
the universe shrinks back down to roughly its current size,
the background temperature would climb back up to a round
room temperature maybe three hundred.
Speaker 1 (27:56):
Kelvin, So the little universe becomes warm and then hot.
Speaker 2 (28:00):
The contraction accelerates dramatically as gravity takes over more strongly.
Davies describes the universe having in size every few million years.
Then faster and faster temperatures soar everywhere. The night sky
wouldn't be dark anymore. It would blaze brighter than the
surface of the Sun. As the CMBPE times get compressed.
Speaker 1 (28:19):
What happens to stars and planets.
Speaker 2 (28:20):
They get cooked. The intense background heat would eventually become
hotter than the cores of stars, causing them to absorb
energy from space and effectively explode or evaporate. All matter
would be torn apart into a hot plasma of elementary particles.
Speaker 1 (28:35):
And this leads to the last three minutes.
Speaker 2 (28:37):
Yes, the final incredibly violent stages. As the universe rushes
towards infinite density, even atomic nuclei would disintegrate. Matter gets
stripped down to its most fundamental constituents, maybe quarks and leptons.
Black holes would find each other rapidly and merge in
spectacular bursts of gravitational waves. Gravity becomes overwhelmingly infinitely powerful,
(28:59):
crushing everything, everything, all matter, space, and even time itself
into a final space time singularity, the Big Crunch, the
mirror image of the Big Bang.
Speaker 1 (29:08):
And as Davies writes, time itself ceases. There's no after
the Big Crunch, no next for anything to happen. It's
the absolute end.
Speaker 2 (29:16):
That's the standard picture. Yes, complete and utter finality.
Speaker 1 (29:20):
But even facing this ultimate, fiery oblivion, some physicists have
speculated about survival. Haven't They could sentient being somehow by
time subjectively, even in a collapsing universe.
Speaker 2 (29:32):
It's even more speculative than Dyson's scenario for the expanding universe,
But yes, the idea has been floated. As the temperature
rises and physical processes speed up dramatically in the collapse.
Speaker 1 (29:43):
Could life speed up its thinking to match.
Speaker 2 (29:45):
Theoretically, maybe, if your thoughts could accelerate at the same
rate as the universe's collapse, you might be able to
cram an infinite amount of subjective experience into the finite
time remaining before the singularity.
Speaker 1 (29:58):
But there are problems with that idea, too big problems.
Speaker 2 (30:01):
One major issue is the speed of light. As space
shrinks rapidly, the time it takes light signals or any
causal influence to cross a brain or computational system might
not shrink fast enough. This could limit the number of
causally connected computational steps, the number of distinct thoughts you
could actually have before the end, So.
Speaker 1 (30:19):
The speed of light becomes a bottleneck.
Speaker 2 (30:21):
Potentially yes. However, some much more complex mathematical models explored
by physicists like Bolinski, Kalatnikov, and Liftshitz suggest the collapse
might not be smooth and uniform. Instead, the universe might
oscillate chaotically as it collapses, sort of wobbling in different directions.
Speaker 1 (30:39):
How would wobbling help?
Speaker 2 (30:40):
While John Burrow and Frank Tipler took this idea and
ran with it, they argued that these chaotic oscillations could
potentially keep different regions of the collapse in universe and
causal contact for longer, and maybe even provide sources of
energy share, allowing for an infinite amount of information processing
to occur before the final singularity.
Speaker 1 (30:59):
So SuperBrain could theoretically compute forever, maybe simulating infinite virtual
worlds right up until the very end.
Speaker 2 (31:07):
That was their highly speculative conjecture. It's important to remember
these are calculations based on classical general relativity and quantum gravity.
Effects near the singularity might completely change the picture, but
it's a fascinating thought experiment about the limits of computation
and consciousness.
Speaker 1 (31:23):
Definitely fascinating, if mind bending. Okay, so we have the
whimper of eternal expansion and the bang of the big crunch,
But dates throws in another possibility, sudden death and rebirth.
What if the end comes without any warning at all?
Speaker 2 (31:40):
Yeah, this is the idea of a catastrophe striking us
from our past light cone, something propagating at the speed
of light, so we literally wouldn't see it coming until
it hit us.
Speaker 1 (31:49):
And the most chilling version of this is vacuum decay.
Speaker 2 (31:52):
It is pretty chilling. Theorists like Sidney Coleman and Frank
DeLucia explored the possibility that the vacuum of empty space
we currently live in, the state with the lowest possible
energy might not actually be the true lowest energy state.
Speaker 1 (32:04):
It could be a false vacuum, like being stuck in
a value when there's an even deeper valley.
Speaker 2 (32:08):
Nearby, exactly a a tastable state. And just like a
quantum particle can tunnel through a barrier, the entire universe,
or at least a patch of it, could spontaneously tunnel
or decay into this hypothesized true vacuum state, the state
with even lower energy.
Speaker 1 (32:25):
What would happen if that occurred.
Speaker 2 (32:26):
A tiny bubble of this true vacuum would suddenly appear somewhere,
maybe through random quantum fluctuation. This bubble would then expand
outwards in all directions at the speed.
Speaker 1 (32:37):
Of light, and inside the bubble.
Speaker 2 (32:38):
The fundamental laws of physics could be drastically different. The
masses of elementary particles, the strengths of forces, everything could
change instantly. Coleman and Deluccio showed that in many scenarios
this change would cause protons to decay almost immediately matter
to essentially evaporate, and the region inside the bubble would
violently implode in microseconds, an instant crunch, but localized to
(33:02):
the expanding bubble.
Speaker 1 (33:03):
They call it the ultimate ecological catastrophe.
Speaker 2 (33:06):
Indeed, you wouldn't see it coming. One moment, everything is normal.
The next you the Earth, the stars, everything inside the
bubble just ceases to exist in its current form.
Speaker 1 (33:15):
That's terrifying. Could we accidentally trigger it like in a
particle accelerator.
Speaker 2 (33:19):
That possibility has been discussed quite seriously. Could smashing particles
together at incredibly high energies create a seed for this
vacuum decay? The calculations suggest it's extremely unlikely with current
or foreseeable accelerators. Plus, nature already performs much higher energy
collisions all the time with cosmic rays hitting the atmosphere,
and the universe seems stable. So while theoretically possible, it's
(33:43):
probably not something to lose sleep over right now?
Speaker 1 (33:46):
Okay? Good? But paradoxically, Davy's notes, this same kind of
physics involving false vacuums and bubbles might offer a radical alternative,
not just death, but rebirth, creating new universes yes.
Speaker 2 (33:59):
This is where it gets really wild, moving into concepts
like eternal inflation. Physicists in Japan and later Alan Guth,
the originator of inflation theory, explored the idea that when
a region of false vacuum undergoes that rapid inflationary expansion,
it doesn't just smooth things out, It can actually bud
off and form a whole new, independent baby universe.
Speaker 1 (34:17):
A baby universe, how is it connected?
Speaker 2 (34:20):
It would initially be connected to the mother universe by
a kind of topological tunnel called a wormhole. From the outside.
In the mother universe, this connection point might just look
like a black hole, But the baby universe itself would
inflate into its own vast expanse of space and time,
potentially with its own slightly different physical laws.
Speaker 1 (34:39):
So our universe could be the child of another older universe.
Speaker 2 (34:43):
That's the implication, and it opens up the truly science
fiction prospect of ultimate emigration. Perhaps incredibly advanced descendants facing
the death of our own universe could learn how to
create a baby universe in a lab, maybe by compressing
matter incredibly densely, and then somehow escape into it.
Speaker 1 (35:01):
Wow, creating a new universe to escape the old one.
Speaker 2 (35:04):
It leads to this picture of cosmic fecundity, maybe a
whole metaverse or multiverse, an infinite family tree of universes
constantly bunting off new ones, with no overall beginning or end,
just endless reproduction. Lee Smallen even proposed a kind of
cosmic natural selection where universes that are good at producing
black holes which might seed new universes, and supporting life
(35:25):
which might learn to create them, become more common.
Speaker 1 (35:27):
It's incredibly speculative.
Speaker 2 (35:29):
Obviously highly speculative, but as Davies suggests, it does offer
a kind of antidote to the ultimate cosmic gloom. Even
if our universe is doomed, maybe consciousness, maybe life alwaysses
somewhere in this grander multiverse.
Speaker 1 (35:42):
Which brings us to the final chapter. Davies explores worlds
without end. He revisits that old, appealing idea of a
cyclic universe, one that expands, crunches, bounces, and extends again,
maybe forever, like in some ancient mythologies.
Speaker 2 (35:58):
Yeah, the idea of eternal cycles is esthetically pleasing to many,
no absolute beginning, no final end, But does it hold
up scientifically?
Speaker 1 (36:06):
What are the challenges?
Speaker 2 (36:07):
The main one pointed out by Richard Tolman back in
the nineteen thirties, is again that pesky second law of
dermodynamics entropy always increases. Irreversible processes happen in each cycle.
Stars burn fuel into heavier elements, radiation builds up black
hole's form and merge.
Speaker 1 (36:22):
So each cycle wouldn't be identical.
Speaker 2 (36:24):
Tolman showed that each cycle would likely start with more entropy,
be bigger, and lasts longer than the previous one. It
wouldn't be truly cyclic in a perfect sense. It would
still be evolving, likely heading towards a kind of heat
death over many many cycles. Plus, if each bounce completely
wipes a slate clean, destroying all information from a previous cycle,
(36:45):
is it really the same universe bouncing or just a
sequence of disconnected universes?
Speaker 1 (36:50):
Good point. What about Andre Lynn's idea of chaotic eternal inflation,
does that offer a kind of endlessness?
Speaker 2 (36:57):
Lin's picture is slightly different. It's suggest us that inflation,
once started, might never completely stop everywhere. Quantum fluctuations would
cause some regions to stop inflating and form bubble universes
like ours, but other regions would just keep inflating. Exponentially forever,
constantly spawning off new bubbles.
Speaker 1 (37:14):
An infinite fractal of universes.
Speaker 2 (37:16):
Sort of yes, and eternally inflating background metaverse, constantly producing
new universes. This seems to offer a theoretical lifeline. Maybe
descendants could somehow travel between bubbles, migrating to younger ones
as their own ages.
Speaker 1 (37:30):
But there's a catch there too.
Speaker 2 (37:31):
A big catch. These bubble universes would typically be expanding
away from each other so fast, faster than light because
space itself is expanding, that they become causally disconnected almost immediately.
You likely couldn't travel between them, and other subtle physical
effects might even create internal event horizons within a single
bubble universe as it ages, potentially trapping inhabitants within their
(37:53):
own region as it slowly reinflates or heads towards its
own end.
Speaker 1 (37:57):
So it seems like no matter which scenario you look,
eternal expansion, big crunch, vacuum decay, baby universes, cycles, eternal inflation,
the end, or at least profound transformation is always lurking
in one form or another.
Speaker 2 (38:11):
Pretty much. Our current understanding suggests the universe as we
know it is not eternal or.
Speaker 1 (38:15):
Static, And all of this inevitably leads back to those
deep philosophical questions, doesn't it Does the universe have a purpose?
If it achieves some purpose? Must it end if it
endures forever? Perhaps aimlessly? Is that pointless?
Speaker 2 (38:29):
Das definitely doesn't shy away from these big questions. At
the end, he frames it beautifully. Perhaps the most that
we can hope for is that the purpose of the
universe becomes known to our descendants before the end of
the last three minutes.
Speaker 1 (38:42):
That's quite a thought to end on a call for understanding, really,
even in the face of potential cosmic oblivion.
Speaker 2 (38:48):
Exactly.
Speaker 1 (38:50):
Wow, Well, we've taken a truly mind bending journey today.
We went from the potential, very real threat of a
comet hitting Earth all the way out to the ultimate
fate of space, time, and matter itself. We've explored these
incredible visions of fire and ice, sudden death, and maybe
even eternal life or the birth of entirely new universes.
Speaker 2 (39:10):
It really covers the whole cosmic story from beginning to
potential ends, and the questions Paul Davies raises in the book.
They aren't just abstract cosmology, are they They touch on
our deepest curiosities about existence, about purpose, about the future
of consciousness itself.
Speaker 1 (39:25):
Absolutely, regardless of whether the universe ultimately ends with a
bang or a whimper, or maybe continues in some endless
cycle of rebirth we can barely conceive of. This deep
dive really reminds us of the incredible scientific ingenuity, the
sheer human drive dedicated to understanding our place in this
fast evolving cosmos.
Speaker 2 (39:44):
It's quite humbling, really, it is.
Speaker 1 (39:46):
So the final thought, perhaps for you listening, what does
it mean for you to live in a universe with
such a rich past, but such an uncertain, potentially finite future,
Knowing these immense time scales that lie ahead, or perhaps
the sudden catastrophes that could occur, what legacy will we
humanity strive to leave
Will the universe end? And if so, how I mean?
Will it be some sudden fiery cataclysm engulfing everything we
know or maybe a slow, quiet fade into oblivion like
a whimper, stretching over unimaginable time. Today we're really diving
into precisely these well profound, mind bending questions. We're using
Paul Davies's fantastic book the last three minutes conjectures about
(00:24):
the ultimate fate of the universe as our guide.
Speaker 2 (00:27):
Welcome to the deep dive. And yeah, this isn't just
about colsmic destruction, not really. It's more like a grand
story of the universe's birth. It's you know, vibrant life
and its many potential deaths. Right, we'll explore the scientific
predictions from the local threats right here on Earth to
the truly universal ones, and we'll see why understanding the
beginning is absolutely key to grasping the end.
Speaker 1 (00:49):
Okay, sounds like a journey, so get ready for time
scales that just challenge the imagination in physics, that'll stretch
your mind. Definitely. All right, let's maybe unpack this with
a bang. Literally. Davies kicks off our story close to home,
painting this vivid, almost cinematic picture of Doom's day on Earth.
Speaker 2 (01:04):
Yeah, it's quite the scene.
Speaker 1 (01:06):
Imagine this August twenty first, twenty one to twenty six.
There's this trillion ton comet Swift Tuttle hurtling towards us
at forty thousand miles prout.
Speaker 2 (01:17):
That's incredibly fast.
Speaker 1 (01:18):
It is. He describes this fiery descent, a thousand cubic
miles of air blasted aside than this searing finger of flame,
wider than a city just lancing the earth. Wow, the
force is catastrophic. I think massive earthquakes, tsunamis, trillions of
tons of rock vaporized, plunging the whole world into darkness.
Speaker 2 (01:37):
It's a truly chilling scenario. And you know, fortunately the
revised calculation shows Swift Tuttle will actually miss us in
twenty one to twenty five.
Speaker 1 (01:44):
Oh good.
Speaker 2 (01:44):
That's a relief, it is, but it really serves as
a stark reminder of a very real, recurring danger. There
are something like ten thousand objects asteroids, commets, maybe half
a kilometer or more across that cross Earth's orbit. Ten thousand, yeah,
and any one of them could cause more damage than
all new clear weapons.
Speaker 1 (02:00):
Combined.
Speaker 2 (02:01):
These kinds of impacts, well, they happen on average every
few million years, like the one that took up the dinosaurs,
you know, sixty five million years ago.
Speaker 1 (02:07):
So okay, a direct impact is terrifying, obviously, but Davies
also suggest we're vulnerable to more subtle cosmic nudges too.
Beyond those direct hits. What are some of those other dangers,
maybe some of the more exotic ones.
Speaker 2 (02:21):
That's right, Well, Jupiter, for instance, it's huge gravity usually
protects us, acting like a cosmic vacuum cleaner in a way, right,
but sometimes it can also slingshot asteroids our way. Then
you've got passing stars that might nudge comets out of
the distant ort cloud sending them towards us the ort
cloud way out there exactly. And then there are the slower,
maybe more insidious threats, things like ecological degradation, climate change,
(02:44):
or even just a slight but sustained variation in the
sum's heat.
Speaker 1 (02:49):
Output, things that unfold over millennia.
Speaker 2 (02:51):
Precisely, which gives humanity a chance to adapt if we're
clever enough, if we can manage it. But ultimately, yeah,
our planet's fate is just inextricably intense with the fate
of the stars and really the whole universe, and this
kind of.
Speaker 1 (03:03):
Leads us naturally to the universe's own inevitable decline. Davies
introduces Herman von Helmholtz's well profoundly depressing prediction from way
back in eighteen fifty six, The universe is dying.
Speaker 2 (03:17):
Yeah, that's a heavy one, and it comes from the
second law of thermodynamics.
Speaker 1 (03:21):
Okay refreshes on that.
Speaker 2 (03:22):
It essentially says that heat always slows from hot to cold,
and this quantity called entropy, it always increases things tend
towards the disorder.
Speaker 1 (03:31):
Basically like a melting ice cube or a cooling cup
of coffee.
Speaker 2 (03:34):
Exactly, heat moves from hotter to colder irreversibly. You can't
really put the heat back easily, and the Sun just
endlessly pouring heat and light out into cold space. That's
a spectacularly irreversible process.
Speaker 1 (03:47):
So it's constantly increasing the universe's total entropy.
Speaker 2 (03:50):
Right, And the ultimate destination of this whole process is
something called heat death. It's a state of maximum entropy
where the entire universe reaches a uniform sort of luke
warm temperature.
Speaker 1 (04:00):
And nothing more can happen pretty much.
Speaker 2 (04:03):
No useful energy transfer can ever happen. Again, nothing of
well value in a physics sense can occur.
Speaker 1 (04:09):
Wow, that sounds incredibly passive for something so vast. Is
there any theoretical loophole? Or is this really it the
universe's ultimate unshakable fate.
Speaker 2 (04:20):
Well, the physics behind it is pretty stark. It certainly
led to some deep philosophical despair for people like Bertran
Russell shaped his atheism even but paradoxically, this very prediction
gives us a surprising clue about the universe's beginning. See,
if the universe is running down at a finite.
Speaker 1 (04:36):
Rate, then it can have existed forever.
Speaker 2 (04:38):
Exactly, it must have had a finite beginning.
Speaker 1 (04:40):
That idea of a finite beginning is really really mind bending.
It even helps solve what seems like a simple observation
but is actually a deep cosmic mystery. Olver's paradox, Why
is the night sky dark? Ah?
Speaker 2 (04:53):
Yeah, Older's paradox? It asks that simple question, why is
the sky dark at night? Sounds trivial, right right, But
if the universe were truly infinite, eternally old, and just
uniformly filled with stars, then literally every single line of
sight you could draw should eventually hit a.
Speaker 1 (05:09):
Star, making the night sky infinitely bright like the surface.
Speaker 2 (05:14):
Of the Sun exactly. The resolution is absolutely central to
modern cosmology. The universe has a finite age, maybe ten
twenty billion years, and crucially, it's expanding.
Speaker 1 (05:27):
So we can only see stars within a certain distance
the observable universe.
Speaker 2 (05:31):
Precisely, there hasn't been enough time for all the starlight
from everywhere to reach us, nor for the universe to
reach that state of thermodynamic equilibrium, that heat death state.
So yeah, this solidifies the idea the universe had a
beginning and it's definitely heading towards an.
Speaker 1 (05:47):
End, so okay. To truly understand the end, Davies argues,
we absolutely have to look to the beginning. And scientists
pretty much unanimously agree the cosmos originated what ten to
twenty billion years ago in the Big Bang.
Speaker 2 (06:00):
It's the consensus. Yeah, And the most direct evidence came
from Edwin Hubble back in the twenties his discovery of
the red shift of distant galaxies showing.
Speaker 1 (06:08):
The light waves are being stretched out right.
Speaker 2 (06:09):
Which tells us the universe is expanding, and crucially It's
not just galaxies flying apart through space, it's that space
itself is stretching between them, carrying them along like buttons
sewn onto an elastic string being stretched.
Speaker 1 (06:21):
That stretching of space. That's a key idea form Einstein's
general relativity, isn't it?
Speaker 2 (06:26):
It is? And if you run that cosmic movie backward,
tracing the expansion back in time, it suggests the universe
started with well zero size, infinite density, infinite expansion rate.
The Big Bang singularity.
Speaker 1 (06:38):
An event that wasn't an explosion.
Speaker 2 (06:40):
In space, but the origin of space, time, matter, and
energy itself. As Davies puts it quite starkly, there was
no before Wow.
Speaker 1 (06:48):
Then in nineteen sixty five came this incredible discovery, the
cosmic afterglow, the cosmic microwave background radiation, the CMBE Yeah.
Speaker 2 (06:57):
The leftover heat from the Big Bang itself. Today it
bathes the entire universe at about three degrees above absolute zero,
just a faint microwave hiss everywhere you look.
Speaker 1 (07:06):
And it's near perfect uniformity. But with these tiny little
temperature ripples discovered later by the Kobe.
Speaker 2 (07:11):
Satellite, those ripples are key. They show the early universe
was incredibly hot, dense, and remarkably smooth, but not perfectly smooth.
Those tiny ripples were the seeds of future galaxies and
cosmic structures.
Speaker 1 (07:23):
And there's more evidence. Right the chemical composition.
Speaker 2 (07:26):
Absolutely the universe is about seventy five percent hydrogen and
twenty five percent helium, with it just trace amounts of
other light elements. This matches perfectly with the predictions of
nuclear reactions happening in the first three minutes after the
Big Bang.
Speaker 1 (07:39):
So the evidence for the Big Bang is strong, But
you mentioned questions remained, like why was it so uniform?
Where did those ripples actually come from exactly?
Speaker 2 (07:47):
The standard Big Bang model didn't quite explain why it
was so smooth, or why the expansion rate seems so
finely tuned. That's where the idea of inflation comes in.
It's a central part of what Davies calls the new
cosmology inflation.
Speaker 1 (08:00):
Okay, what's the core idea there.
Speaker 2 (08:02):
The idea, and it's pretty audacious, is that in the
very first tiny fraction of a second, like ten to
the minus thirty five seconds, the universe underwent this brief
but incredibly rapid exponential expansion much much faster than the
later expansion.
Speaker 1 (08:17):
Like hitting a cosmic accelerator pedal sort of.
Speaker 2 (08:19):
Yeah, powered by a peculiar unstable energy state called a
false vacuum. Think of it as a supercharged but temporary
kind of emptiness that exerted a sort of anti gravity
or negative pressure, driving this hyper expansion.
Speaker 1 (08:32):
And this inflation solves those problems.
Speaker 2 (08:34):
It does rather elegantly. This enormous rapid stretching would naturally
smooth out any initial bumps or irregularities, explaining the observed uniformity.
It also explains why the universe is so vast and
those tiny quantum fluctuations happening during inflation.
Speaker 1 (08:49):
It gets stretched out too.
Speaker 2 (08:51):
Exactly, They get blown up to cosmic scales, providing the
seeds for the ripples we see in the CMB, which
eventually grew into galaxies. It's mine bending. The basic structure
of the universe might have been set in just ten
thirty two seconds.
Speaker 1 (09:04):
Incredible, So, as Davey says, the beginning and the end
of the universe are deeply intertwined.
Speaker 2 (09:09):
Absolutely, you can't really understand one without the other.
Speaker 1 (09:12):
Okay, let's zoom back in now, from the whole cosmos
to individual cosmic drama the birth and Death of stars.
Davis calls it stardom. He starts with supernova nineteen eighty seven.
Speaker 2 (09:22):
A ah yes, nineteen eighty seven a a huge event
for astronomers, the first supernova visible to the naked eye
since sixteen oh four.
Speaker 1 (09:30):
But the really surprising part Davy's notes came hours before
the visible light arrived. Deep underground. In detectors in Japan
and Ohio.
Speaker 2 (09:38):
They picked up bursts of neutrinos. Wolfgang Polly's spinning goes,
these incredibly elusive particles with almost no mass, no charge,
barely interacting with anything.
Speaker 1 (09:49):
And detecting those neutrinos at the same time as the supernova.
That was huge, right.
Speaker 2 (09:53):
It was crucial confirmation of supernova theory. It showed what
happens inside these massive stars. They fuse lighter el elements
into heavier ones, hydrogen to helium, helium to carbon, and
so on up the.
Speaker 1 (10:04):
Periodic table until they hit iron.
Speaker 2 (10:06):
Exactly fusin iron costs energy, it doesn't release it, so
the star's core suddenly loses its energy source. It can
no longer support itself against its own immense gravity, and
it collapses catastrophically. It implodes, bounces off the super dense core,
creating a massive shock wave, and that tremendous burst of
neutrinos we detected. Then the outer layers explode outwards with
(10:27):
the light intensity of maybe ten billion suns.
Speaker 1 (10:31):
Wow, and these incredibly violent deaths. Yeah, they aren't just destructive,
are they? Note at all?
Speaker 2 (10:36):
They're fundamentally creative. Supernovas are the cosmic forges that create
all the heavy elements heavier than iron, things like gold, lead, uranium,
and then they scatter this precious stuff across space.
Speaker 1 (10:48):
So Davies reminds us the very stuff of our bodies
is composed of the nuclear ash of long dead stars.
Speaker 2 (10:55):
It's quite poetic, but literally true. And what's left behind
after the explos either an incredibly dense neutron star, maybe
the size of a city but with more mass than
the Sun, or for even more massive stellar cores, a
black hole.
Speaker 1 (11:09):
But our own Sun. It's not massive enough for that
kind of fireworks, right correct.
Speaker 2 (11:15):
Our Sun will have a gentler, though still pretty dramatic
for us demise. It's about halfway through its ten billion
year hydrogen burning life. Now, in another five billion years
or so, it'll run out of hydrogen in its core
and start fusing hydrogen in a shell around the core,
and that makes it swell up dramatically. It'll become a
red giant, swelling perhaps hundreds of times its current size,
(11:35):
likely engulfing mercury Venus and almost certainly Earth.
Speaker 1 (11:39):
So Earth gets incinerated.
Speaker 2 (11:40):
Yeah, Unfortunately, Then, after maybe shedding its outer layers as
a planetary nebula, the Sun's core will shrink down into
a white dwarf. A white dwarf, it's a small, incredibly
dense cinder, about the size of Earth but containing maybe
half the Sun's original mass. It's very hot initially, but
it has no more fuel to burn, so it just
slowly cools down over trillions of years, eventually solidifying maybe
(12:04):
into a crystal structure, and fading into blackness, A black dwarf.
Speaker 1 (12:08):
A quiet end for stars like ours, Yeah, but it's
still an end, a sort of prelude to this wider
cosmic nightfall.
Speaker 2 (12:15):
You mentioned exactly.
Speaker 1 (12:16):
So our own Sun becomes a cold, dark ember. But
what happens much much later, when all the stars across
the entire cosmos have finally dimmed and died out. That's
its chilling prospect Davies calls nightfall.
Speaker 2 (12:29):
Right, the universe currently lit up by nuclear fusion and
stars will eventually exhaust this primary energy source. New star
formation will basically cease as the intercellar gas gets used
up or locked away. The universe just gets inexorably dimmer.
The era of light, as Davies puts, it, will be
over forever.
Speaker 1 (12:45):
But the story doesn't end just when the lights go out,
does it? Because gravity is still there.
Speaker 2 (12:50):
Gravity is always there. Even though it's the weakest fundamental
force on cosmic scales and over cosmic time scales, it
remains utterly dominant. Long after nuclear energy is gone. Gravity
continues to shape the universe's.
Speaker 1 (13:02):
Fate, and gravity is linked to black holes, which you
mentioned are the remnants of massive stars. These seem to
hold immense power.
Speaker 2 (13:09):
They really do. Black holes represent gravity's ultimate triumph, crushing
matter essentially to a point of infinite density, warping space
time around them intensely. Davies uses this thought experiment. Imagine
lowering a weight slowly towards a black hole on a pulley. Okay,
in principle, as the weight falls in, you could extract
(13:31):
almost all of its rest mass energy EMC squared. It
does work. That's potentially over one hundred times more energy
than you get from nuclear fusion.
Speaker 1 (13:39):
Wow. Is there any real world evidence for that kind
of power?
Speaker 2 (13:42):
Absolutely? We see it in systems like Signus X one.
It's a binary star system where we see a visible
star orbiting something invisible, but that invisible companion is pouring
out intense X rays, which comes from matter being pulled
off the visible star heating up to millions of degrees
as it spirals into the intense gravity of the unseen companion,
which has to be a black hole. We also see
(14:04):
super massive black holes at the centers of most galaxies,
including our own Milky Ways Sagittarius A. They power incredibly
energetic phenomena like quasars and jets.
Speaker 1 (14:14):
And these powerful objects. Yeah, they don't just sit still either. Right.
You mentioned gravity waves, right.
Speaker 2 (14:19):
Einstein's theory predicted that accelerating massive objects should create ripples
in the fabric of space time itself, gravitational waves. We've
now directly detected these famously from merging black holes and
also merging neutron stars.
Speaker 1 (14:32):
Like those binary neutron stars in Akola exactly.
Speaker 2 (14:35):
We observe them slowly spiraling closer together over decades, losing
energy precisely as predicted by emitting gravitational waves before they
finally merged. When black holes merge, they can release a
truly staggering amount of energy, potentially up to two thirds
of their total mass energy purely as gravitational waves.
Speaker 1 (14:54):
That's immense energy, and falling into one Detes describes a
two doesn'ty spaghetification does.
Speaker 2 (15:00):
If you are unlucky enough to fall into a black hole,
you'd first cross the event horizon, the point of no
return where even light can't escape inside, the tidal forces
become extreme. The gravity at your feet would be so
much stronger than at your head that you'd be stretched
out like spaghetti while simultaneously being squeezed from the sides. Ultimately,
(15:21):
you'd reach the central space time singularity, a point where
our current understanding of physics breaks down. Gravity becomes infinite,
and space and time, at least for you, would simply end.
Speaker 1 (15:32):
So Ultimately, gravity's cumulative action over these vast time scales
is what determines the universe's final fate.
Speaker 2 (15:39):
That's the core idea.
Speaker 1 (15:41):
Which brings us right back to that great cosmic question,
will the universe expand forever, cooling and dimming, or will
gravity eventually win out, halting the expansion and pulling everything
back together in a big crunch.
Speaker 2 (15:52):
And the answer hinges quite literally, on how much the
universe weighs its overall density of matter and energy.
Speaker 1 (15:59):
How do we even begin to weigh the universe?
Speaker 2 (16:01):
Yeah, well it's not easy. If you just count up
all the visible stuff, stars, galaxies, gas clouds, the total
mass seems too low. It suggests the universe's gravity isn't
strong enough to stop the expansion. It would expand forever.
Speaker 1 (16:15):
There's a catch, isn't there? Dark matter?
Speaker 2 (16:17):
The big catch? Most of the universes matter, it turns out,
is completely unseen. It doesn't shine, it doesn't absorb light,
it doesn't reflect light. It's dark.
Speaker 1 (16:26):
So what could this dark matter be?
Speaker 2 (16:27):
Well, there are several candidates. One possibility is neutrinos. We
know there are vast numbers of them left over from
the Big Bang, maybe a billion for every proton or neutron.
Speaker 1 (16:37):
Those ghostly particles again.
Speaker 2 (16:39):
Yeah, and while they were originally thought to be massless,
we now know they have a tiny, tiny mass. It's
not much individually, but there are so many of them.
That collectively they could potentially outweigh all the stars combine.
Supernova nineteen eighty seven A actually helped put some limits
on their mass.
Speaker 1 (16:57):
Okay, what else?
Speaker 2 (16:57):
Then? There are more exotic hypothetic particles, often lumped together
as WIMPs, weakly interacting massive particles, things predicted by theories
beyond the standard model of particle physics, like gravitinos or fatinos.
There are incredibly ambitious experiments deep underground trying to detect
the very faint bang one of these might make if
(17:19):
it occasionally bumps into an atomic nucleus, and a super
cooled crystal detector.
Speaker 1 (17:24):
Searching for ghosts in the dark. Basically, what's the actual
evidence that this stuff exists? Though?
Speaker 2 (17:29):
If we can't see it directly, the astronomical evidence is
really overwhelming. Actually, it comes from multiple directions. One classic
example is galaxy rotation.
Speaker 1 (17:37):
Curves, how stars move within galaxies.
Speaker 2 (17:40):
Exactly, you'd expect stars farther out from the center of
a galaxy to orbit slower, just like planets farther from
the Sun orbit slower. But that's not what we see.
Stars in the outer parts of galaxies orbit at roughly
the same speed as stars closer in, which means it
means there must be a huge amount of unseen mass
extending far beyond the visit disc of the galaxy, creating
(18:02):
extra gravity to hold on to those fast moving outer stars.
This invisible dark matter halo seems to contain maybe ten
to one hundred times more mass than all the luminous
matter the stars and gas we can see.
Speaker 1 (18:14):
Wow, ten to one hundred times more.
Speaker 2 (18:16):
Yeah, And we see similar evidence in clusters of galaxies.
The individual galaxies within large clusters like the Coma cluster
are moving around much too fast to stay gravitationally bond
together unless there's hundreds of times more mass present than
what we see in the galaxies themselves.
Speaker 1 (18:33):
So the clusters should have flown apart long ago if
it wasn't for dark matter holding them together.
Speaker 2 (18:37):
Precisely, even the large scale structure of the universe, the
way galaxies are arranged in these vast filaments and sheets
with voids in between, this sort of cosmic web requires
the extra gravitational pull of dark matter to form over
the age of the universe.
Speaker 1 (18:51):
Okay, so dark matter seems to outweigh normal matter by
at least ten to one, maybe much more. Does that
mean the universe will eventually collapse. Does it tip the scales?
Speaker 2 (18:59):
That's the t trillion dollar question. It definitely adds a
lot more weight, but whether it's enough to cause a
big crunch is still uncertain. Interestingly, the theory of inflation
that rapid expansion early on actually makes a prediction.
Speaker 1 (19:12):
Here, Oh, what does inflation predict about the universe's density?
Speaker 2 (19:17):
It predicts that the universe's overall density should be extremely
close to the critical density, the exact value needed to
eventually halt the expansion, but just barely so. The universe
might be balanced.
Speaker 1 (19:29):
On a knife edge, meaning if it does collapse.
Speaker 2 (19:32):
It will happen in the very very very distant future.
We're talking trillions upon trillions of years from now, maybe
so far off that the difference between eternal expansion and
eventual collapse is practically undetectable for us now.
Speaker 1 (19:45):
So the universe faces these two main paths, these two
potential ultimate fates eternal expansion leading to a cold, dark
whimper or eventual collapse into a hot, fiery big crunch,
and each one has starkly different implications for the ultra
long term future.
Speaker 2 (20:00):
Exactly two very different endgames.
Speaker 1 (20:02):
Let's explore that first possibility, then the whimper scenario. If
the universe expands forever, Davies paints a picture of a
bleak infinity. He stresses that infinity is qualitatively different from
supendously huge.
Speaker 2 (20:17):
Yeah, that's a key point. In an infinite amount of time,
anything that can happen, no matter how improbable, will eventually happen.
Speaker 1 (20:24):
So imagine the universe, say a trillion trillion years from now,
what does it look like?
Speaker 2 (20:28):
Utterly dark, incredibly diluted, filled only with the cold cinders
of stars, black dwarfs, neutrons, stars, and of course black holes,
all drifting ever farther apart as space continues to expand.
Speaker 1 (20:40):
But gravity isn't completely done yet. Even then, not quite.
Speaker 2 (20:44):
Even in this incredibly dispersed state, gravity still operates. Gravitational
wave emission, although incredibly feeble from orbiting dead stars, will
continue over unimaginable timescales.
Speaker 1 (20:55):
Causing them to spiral into each other.
Speaker 2 (20:57):
Eventually, yes, dead stars will slow spiral into each other
and merge, or they'll fall into the supermassive black holes
at the centers of what used to be galaxies. Also,
gravitational interactions like near misses between these stellar remnants will
act like slingshots, ejecting most objects out of their original
clusters into the vast emptiness of intergalactic space.
Speaker 1 (21:18):
And even the black holes, right, they don't last forever either.
You mentioned Hawking radiation, right.
Speaker 2 (21:24):
Stephen Hawking's ground broking discovery in the nineteen seventies was
that black holes aren't truly black due to quantum effects
near the event horizon, involving pairs of virtual particles popping
into existence. Black holes actually emit a faint thermal glow,
now called Hawking radiation, so they slowly evaporate, very very slowly.
The smaller the black hole, the hotter it is, and
(21:45):
the faster it evaporates. A solar mass black hole would
take something like one hundred and sixty six years to
evaporate completely. Larger ones like the supermassive ones and galactic
centers take vastly longer, maybe ten hundred and ninety three
years or more, But eventually even they should disappear in
a final burst of energy.
Speaker 1 (22:02):
Tend to the power of ninety three years. That's just
impossible to grasp. But the disintegration doesn't stop there, does it.
What about ordinary matter itself.
Speaker 2 (22:10):
Yeah, this is where it gets even weirder. Even things
we think of as perfectly stable, like protons or even
the structure of atoms, might be unstable over these truly
immense time scales. Freeman Dyson pointed out this bizarre quantum
effect called quantum tunneling. Got It's a quantum mechanical phenomenon
where a particle can, with a very small probability, pass
(22:32):
through an energy barrier, even if it doesn't technically have
enough energy to go over it. Over incredibly long time spans,
these tiny probabilities add up. Dyson calculated that even something
like a diamond, seemingly eternal, would eventually, after maybe ten thousand,
sixty five years, slowly rearranges atoms via tunneling into a
more stable spherical configuration like a featureless bead.
Speaker 1 (22:53):
Diamonds turn into beads okay, and protons the very building
blocks of atoms.
Speaker 2 (22:58):
Well. Many modern physics theories be Beyon the standard model
called gran unified theories or GUTS, predict that protons themselves
might not be truly stable. They might decay, perhaps into
lighter particles like a positron and a pion, over incredibly
long time scales maybe ten thousand and thirty two years,
or longer.
Speaker 1 (23:16):
Ten to the thirty two years. So if protons.
Speaker 2 (23:18):
Decay, then all ordinary matter, planets, dead stars, everything made
of atoms would eventually just evaporate into a bath of
radiation and lighter particles. Experiments are actually running right now,
deep underground in places like Commioca looking for the telltale
flashes of light from a decaying proton, but so far
none have been definitively seen, meaning the lifetime is at
(23:39):
least that long, if not infinite.
Speaker 1 (23:40):
So after proton decay, after black hole evaporation, what's left
the ultimate.
Speaker 2 (23:46):
Residue an inconceivably dilute, cold, dark soup mostly photons and
neutrinos from all the decay processes, plus maybe a dwindling
smattering of electrons and positrons, all drifting ever farther apart
in the eternally expanding space, just leaks sterility. This is
the modern conception of the heat death.
Speaker 1 (24:03):
Bleak, indeed, which brings us back to that human question.
Even in this desolate, far flung future, could life or
perhaps our distant descendants possibly persist, Could consciousness somehow survive?
Speaker 2 (24:16):
That is the ultimate question in this scenario, isn't it It
certainly seems chilling, almost futile. It makes you circle back
to the bertrand Russell's despair. If everything eventually fades to nothingness,
what's the point exactly?
Speaker 1 (24:28):
How does Davies tackle that? Does he offer any hope
any way for humanity or perhaps intelligence itself, to achieve
some kind of immortality, maybe what he calls life in
the slow lane?
Speaker 2 (24:38):
He does challenge that despair. He first points out humanity's
potential for long term survival and adaptation, even on cosmic scales.
He envisions our descendants potentially colonizing the galaxy through planet hopping,
maybe using genetically engineered being suited for different environments, or
perhaps arcships carrying frozen embryos. This could happen in maybe
just thirty million years or so.
Speaker 1 (25:00):
Thirty million years sounds long to us, but it's a blinking.
Speaker 2 (25:02):
Cosmic time, right, and he speculates that future beings might
not even resemble us physically. They could be genetically modified
or even post biological entities, cyborg sophisticated organic computers, maybe
vast neural networks inhabiting space itself. The focus shifts from
preserving are exact physical form to preserving the human spirit, culture,
(25:25):
knowledge values thought itself.
Speaker 1 (25:27):
But how do you preserve thought when the universe is
running down, energy is becoming scarce, and everything is cooling
towards absolute zero. That's where Freeman Dyson's idea comes in, right.
Speaker 2 (25:37):
Yes, Dyson's really fascinating scenario for achieving subjective immortality in
an eternally expanding, cooling universe. The key problem is that
any thought process, any computation, requires energy and necessarily dissipate
some of that energy as waste heat, increasing entropy. You
can't think for free thermodynamically.
Speaker 1 (25:55):
Speaking, so how do you heat around that?
Speaker 2 (25:57):
Dyson's ingenious idea is that sentient beings could a dapt
by progressively slowing down their metabolic rate their thinking processes.
As the universe cools, they would cool down with it,
entering periods of hibernation for longer and longer.
Speaker 1 (26:08):
Durations, hybridating for millions, billions, trillions of years exactly.
Speaker 2 (26:13):
This allows them to conserve their finite energy resources, letting
energies slowly accumulate between brief periods of activity, and giving
the waste heat plenty of time to dissipate into the
increasingly cold background. By doing this, living it down, as
Davies puts it, they could potentially stretch a finite amount
of energy over an infinite amount of subjective time. They
(26:35):
could experience an infinite number of thoughts.
Speaker 1 (26:37):
Infinite thoughts with finite energy by slowing down infinitely.
Speaker 2 (26:43):
That's the concept. There are debates about whether you could
have an infinite number of different thoughts, which might depend
on whether computation is fundamentally digital or analog, but the
principle is there. It suggests a way. However, desperate for
consciousness to persist indefinitely, a struggle against the dying of
the light. It offers a sliver of hope against the
bleakness if the universe expands forever.
Speaker 1 (27:04):
A desperate hope maybe. But what about the other fork
in the road. What if the universe's ultimate fate isn't
that slow fade, but a fiery end the Big Crunch scenario.
If there is enough dark matter, enough total.
Speaker 2 (27:16):
Density, then gravity eventually wins. It halts the cosmic expansion,
perhaps trillions of years from now, and begins to pull
everything back together.
Speaker 1 (27:25):
The universe starts contracting. What would that look like.
Speaker 2 (27:28):
Initially, it would be the expansion in reverse, but very
slow at first. Galaxies would stop receding from each other
and start falling back together. The cosmic microwave background radiation,
which has been cooling ever since the Big Bang. As
space six panded, it.
Speaker 1 (27:42):
Would start heat up again. As space contracts.
Speaker 2 (27:44):
Exactly, it gets blue shifted instead of red shifted. As
the universe shrinks back down to roughly its current size,
the background temperature would climb back up to a round
room temperature maybe three hundred.
Speaker 1 (27:56):
Kelvin, So the little universe becomes warm and then hot.
Speaker 2 (28:00):
The contraction accelerates dramatically as gravity takes over more strongly.
Davies describes the universe having in size every few million years.
Then faster and faster temperatures soar everywhere. The night sky
wouldn't be dark anymore. It would blaze brighter than the
surface of the Sun. As the CMBPE times get compressed.
Speaker 1 (28:19):
What happens to stars and planets.
Speaker 2 (28:20):
They get cooked. The intense background heat would eventually become
hotter than the cores of stars, causing them to absorb
energy from space and effectively explode or evaporate. All matter
would be torn apart into a hot plasma of elementary particles.
Speaker 1 (28:35):
And this leads to the last three minutes.
Speaker 2 (28:37):
Yes, the final incredibly violent stages. As the universe rushes
towards infinite density, even atomic nuclei would disintegrate. Matter gets
stripped down to its most fundamental constituents, maybe quarks and leptons.
Black holes would find each other rapidly and merge in
spectacular bursts of gravitational waves. Gravity becomes overwhelmingly infinitely powerful,
(28:59):
crushing everything, everything, all matter, space, and even time itself
into a final space time singularity, the Big Crunch, the
mirror image of the Big Bang.
Speaker 1 (29:08):
And as Davies writes, time itself ceases. There's no after
the Big Crunch, no next for anything to happen. It's
the absolute end.
Speaker 2 (29:16):
That's the standard picture. Yes, complete and utter finality.
Speaker 1 (29:20):
But even facing this ultimate, fiery oblivion, some physicists have
speculated about survival. Haven't They could sentient being somehow by
time subjectively, even in a collapsing universe.
Speaker 2 (29:32):
It's even more speculative than Dyson's scenario for the expanding universe,
But yes, the idea has been floated. As the temperature
rises and physical processes speed up dramatically in the collapse.
Speaker 1 (29:43):
Could life speed up its thinking to match.
Speaker 2 (29:45):
Theoretically, maybe, if your thoughts could accelerate at the same
rate as the universe's collapse, you might be able to
cram an infinite amount of subjective experience into the finite
time remaining before the singularity.
Speaker 1 (29:58):
But there are problems with that idea, too big problems.
Speaker 2 (30:01):
One major issue is the speed of light. As space
shrinks rapidly, the time it takes light signals or any
causal influence to cross a brain or computational system might
not shrink fast enough. This could limit the number of
causally connected computational steps, the number of distinct thoughts you
could actually have before the end, So.
Speaker 1 (30:19):
The speed of light becomes a bottleneck.
Speaker 2 (30:21):
Potentially yes. However, some much more complex mathematical models explored
by physicists like Bolinski, Kalatnikov, and Liftshitz suggest the collapse
might not be smooth and uniform. Instead, the universe might
oscillate chaotically as it collapses, sort of wobbling in different directions.
Speaker 1 (30:39):
How would wobbling help?
Speaker 2 (30:40):
While John Burrow and Frank Tipler took this idea and
ran with it, they argued that these chaotic oscillations could
potentially keep different regions of the collapse in universe and
causal contact for longer, and maybe even provide sources of
energy share, allowing for an infinite amount of information processing
to occur before the final singularity.
Speaker 1 (30:59):
So SuperBrain could theoretically compute forever, maybe simulating infinite virtual
worlds right up until the very end.
Speaker 2 (31:07):
That was their highly speculative conjecture. It's important to remember
these are calculations based on classical general relativity and quantum gravity.
Effects near the singularity might completely change the picture, but
it's a fascinating thought experiment about the limits of computation
and consciousness.
Speaker 1 (31:23):
Definitely fascinating, if mind bending. Okay, so we have the
whimper of eternal expansion and the bang of the big crunch,
But dates throws in another possibility, sudden death and rebirth.
What if the end comes without any warning at all?
Speaker 2 (31:40):
Yeah, this is the idea of a catastrophe striking us
from our past light cone, something propagating at the speed
of light, so we literally wouldn't see it coming until
it hit us.
Speaker 1 (31:49):
And the most chilling version of this is vacuum decay.
Speaker 2 (31:52):
It is pretty chilling. Theorists like Sidney Coleman and Frank
DeLucia explored the possibility that the vacuum of empty space
we currently live in, the state with the lowest possible
energy might not actually be the true lowest energy state.
Speaker 1 (32:04):
It could be a false vacuum, like being stuck in
a value when there's an even deeper valley.
Speaker 2 (32:08):
Nearby, exactly a a tastable state. And just like a
quantum particle can tunnel through a barrier, the entire universe,
or at least a patch of it, could spontaneously tunnel
or decay into this hypothesized true vacuum state, the state
with even lower energy.
Speaker 1 (32:25):
What would happen if that occurred.
Speaker 2 (32:26):
A tiny bubble of this true vacuum would suddenly appear somewhere,
maybe through random quantum fluctuation. This bubble would then expand
outwards in all directions at the speed.
Speaker 1 (32:37):
Of light, and inside the bubble.
Speaker 2 (32:38):
The fundamental laws of physics could be drastically different. The
masses of elementary particles, the strengths of forces, everything could
change instantly. Coleman and Deluccio showed that in many scenarios
this change would cause protons to decay almost immediately matter
to essentially evaporate, and the region inside the bubble would
violently implode in microseconds, an instant crunch, but localized to
(33:02):
the expanding bubble.
Speaker 1 (33:03):
They call it the ultimate ecological catastrophe.
Speaker 2 (33:06):
Indeed, you wouldn't see it coming. One moment, everything is normal.
The next you the Earth, the stars, everything inside the
bubble just ceases to exist in its current form.
Speaker 1 (33:15):
That's terrifying. Could we accidentally trigger it like in a
particle accelerator.
Speaker 2 (33:19):
That possibility has been discussed quite seriously. Could smashing particles
together at incredibly high energies create a seed for this
vacuum decay? The calculations suggest it's extremely unlikely with current
or foreseeable accelerators. Plus, nature already performs much higher energy
collisions all the time with cosmic rays hitting the atmosphere,
and the universe seems stable. So while theoretically possible, it's
(33:43):
probably not something to lose sleep over right now?
Speaker 1 (33:46):
Okay? Good? But paradoxically, Davy's notes, this same kind of
physics involving false vacuums and bubbles might offer a radical alternative,
not just death, but rebirth, creating new universes yes.
Speaker 2 (33:59):
This is where it gets really wild, moving into concepts
like eternal inflation. Physicists in Japan and later Alan Guth,
the originator of inflation theory, explored the idea that when
a region of false vacuum undergoes that rapid inflationary expansion,
it doesn't just smooth things out, It can actually bud
off and form a whole new, independent baby universe.
Speaker 1 (34:17):
A baby universe, how is it connected?
Speaker 2 (34:20):
It would initially be connected to the mother universe by
a kind of topological tunnel called a wormhole. From the outside.
In the mother universe, this connection point might just look
like a black hole, But the baby universe itself would
inflate into its own vast expanse of space and time,
potentially with its own slightly different physical laws.
Speaker 1 (34:39):
So our universe could be the child of another older universe.
Speaker 2 (34:43):
That's the implication, and it opens up the truly science
fiction prospect of ultimate emigration. Perhaps incredibly advanced descendants facing
the death of our own universe could learn how to
create a baby universe in a lab, maybe by compressing
matter incredibly densely, and then somehow escape into it.
Speaker 1 (35:01):
Wow, creating a new universe to escape the old one.
Speaker 2 (35:04):
It leads to this picture of cosmic fecundity, maybe a
whole metaverse or multiverse, an infinite family tree of universes
constantly bunting off new ones, with no overall beginning or end,
just endless reproduction. Lee Smallen even proposed a kind of
cosmic natural selection where universes that are good at producing
black holes which might seed new universes, and supporting life
(35:25):
which might learn to create them, become more common.
Speaker 1 (35:27):
It's incredibly speculative.
Speaker 2 (35:29):
Obviously highly speculative, but as Davies suggests, it does offer
a kind of antidote to the ultimate cosmic gloom. Even
if our universe is doomed, maybe consciousness, maybe life alwaysses
somewhere in this grander multiverse.
Speaker 1 (35:42):
Which brings us to the final chapter. Davies explores worlds
without end. He revisits that old, appealing idea of a
cyclic universe, one that expands, crunches, bounces, and extends again,
maybe forever, like in some ancient mythologies.
Speaker 2 (35:58):
Yeah, the idea of eternal cycles is esthetically pleasing to many,
no absolute beginning, no final end, But does it hold
up scientifically?
Speaker 1 (36:06):
What are the challenges?
Speaker 2 (36:07):
The main one pointed out by Richard Tolman back in
the nineteen thirties, is again that pesky second law of
dermodynamics entropy always increases. Irreversible processes happen in each cycle.
Stars burn fuel into heavier elements, radiation builds up black
hole's form and merge.
Speaker 1 (36:22):
So each cycle wouldn't be identical.
Speaker 2 (36:24):
Tolman showed that each cycle would likely start with more entropy,
be bigger, and lasts longer than the previous one. It
wouldn't be truly cyclic in a perfect sense. It would
still be evolving, likely heading towards a kind of heat
death over many many cycles. Plus, if each bounce completely
wipes a slate clean, destroying all information from a previous cycle,
(36:45):
is it really the same universe bouncing or just a
sequence of disconnected universes?
Speaker 1 (36:50):
Good point. What about Andre Lynn's idea of chaotic eternal inflation,
does that offer a kind of endlessness?
Speaker 2 (36:57):
Lin's picture is slightly different. It's suggest us that inflation,
once started, might never completely stop everywhere. Quantum fluctuations would
cause some regions to stop inflating and form bubble universes
like ours, but other regions would just keep inflating. Exponentially forever,
constantly spawning off new bubbles.
Speaker 1 (37:14):
An infinite fractal of universes.
Speaker 2 (37:16):
Sort of yes, and eternally inflating background metaverse, constantly producing
new universes. This seems to offer a theoretical lifeline. Maybe
descendants could somehow travel between bubbles, migrating to younger ones
as their own ages.
Speaker 1 (37:30):
But there's a catch there too.
Speaker 2 (37:31):
A big catch. These bubble universes would typically be expanding
away from each other so fast, faster than light because
space itself is expanding, that they become causally disconnected almost immediately.
You likely couldn't travel between them, and other subtle physical
effects might even create internal event horizons within a single
bubble universe as it ages, potentially trapping inhabitants within their
(37:53):
own region as it slowly reinflates or heads towards its
own end.
Speaker 1 (37:57):
So it seems like no matter which scenario you look,
eternal expansion, big crunch, vacuum decay, baby universes, cycles, eternal inflation,
the end, or at least profound transformation is always lurking
in one form or another.
Speaker 2 (38:11):
Pretty much. Our current understanding suggests the universe as we
know it is not eternal or.
Speaker 1 (38:15):
Static, And all of this inevitably leads back to those
deep philosophical questions, doesn't it Does the universe have a purpose?
If it achieves some purpose? Must it end if it
endures forever? Perhaps aimlessly? Is that pointless?
Speaker 2 (38:29):
Das definitely doesn't shy away from these big questions. At
the end, he frames it beautifully. Perhaps the most that
we can hope for is that the purpose of the
universe becomes known to our descendants before the end of
the last three minutes.
Speaker 1 (38:42):
That's quite a thought to end on a call for understanding, really,
even in the face of potential cosmic oblivion.
Speaker 2 (38:48):
Exactly.
Speaker 1 (38:50):
Wow, Well, we've taken a truly mind bending journey today.
We went from the potential, very real threat of a
comet hitting Earth all the way out to the ultimate
fate of space, time, and matter itself. We've explored these
incredible visions of fire and ice, sudden death, and maybe
even eternal life or the birth of entirely new universes.
Speaker 2 (39:10):
It really covers the whole cosmic story from beginning to
potential ends, and the questions Paul Davies raises in the book.
They aren't just abstract cosmology, are they They touch on
our deepest curiosities about existence, about purpose, about the future
of consciousness itself.
Speaker 1 (39:25):
Absolutely, regardless of whether the universe ultimately ends with a
bang or a whimper, or maybe continues in some endless
cycle of rebirth we can barely conceive of. This deep
dive really reminds us of the incredible scientific ingenuity, the
sheer human drive dedicated to understanding our place in this
fast evolving cosmos.
Speaker 2 (39:44):
It's quite humbling, really, it is.
Speaker 1 (39:46):
So the final thought, perhaps for you listening, what does
it mean for you to live in a universe with
such a rich past, but such an uncertain, potentially finite future,
Knowing these immense time scales that lie ahead, or perhaps
the sudden catastrophes that could occur, what legacy will we
humanity strive to leave
Popular Podcasts
My Favorite Murder with Karen Kilgariff and Georgia Hardstark
My Favorite Murder is a true crime comedy podcast hosted by Karen Kilgariff and Georgia Hardstark. Each week, Karen and Georgia share compelling true crimes and hometown stories from friends and listeners. Since MFM launched in January of 2016, Karen and Georgia have shared their lifelong interest in true crime and have covered stories of infamous serial killers like the Night Stalker, mysterious cold cases, captivating cults, incredible survivor stories and important events from history like the Tulsa race massacre of 1921. My Favorite Murder is part of the Exactly Right podcast network that provides a platform for bold, creative voices to bring to life provocative, entertaining and relatable stories for audiences everywhere. The Exactly Right roster of podcasts covers a variety of topics including historic true crime, comedic interviews and news, science, pop culture and more. Podcasts on the network include Buried Bones with Kate Winkler Dawson and Paul Holes, That's Messed Up: An SVU Podcast, This Podcast Will Kill You, Bananas and more.
24/7 News: The Latest
The latest news in 4 minutes updated every hour, every day.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com