Far out into the darkness, a single
ember speckles against the black.
The very last star,
inching through every remaining scrap of
fuel it could find. It has eaked out to
meager existence for trillions of years.
But slowly, inevitably, it fades. thus
bringing the curtain down on the
greatest show the universe has ever
known. All that remains are relics of a
bicon age. Black dwarfs, neutron stars,
and above all, black holes. These
stellar corpses but eerie reminders of
the joys of youth. But they too are
mortal. And after an inconceivably long
time, even they flicker and vanish.
Now the ancient universe appears empty.
But it is not.
There are still monsters lurking in the
shadows. Monsters called forth by the
ocean of quantum waves that fill the
cosmos. And this is particularly true if
time never ends. If it is infinite, then
every possible quantum fluctuation is
guaranteed to play out eventually. Given
enough time, quantum fields will
occasionally arrange themselves into
fleeting pockets of order. A stray atom
here, a complex molecule there, a warm
clump in a cold void. Indeed, there is
no principle that forbids such
accidents. Only the low odds delay them.
And infinite time is merciless even with
the lowest odds.
And if we follow this logic far enough,
it leads somewhere deeply unsettling.
For if order can arise by chance, then
so can experience.
A flash of awareness assembled from
chaos not born of stars or planets or
evolution but conjured briefly by
quantum fluctuations and statistics
alone. And in an eternal universe, the
familiar cosmic story, the one of
galaxies, biology, and history risks
becoming the exception rather than the
rule.
After all, endings matter. Endings give
us meaning. Without them, things quickly
become very strange indeed.
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Dawn rises slowly over the terracotta
rooftops of Prague. In the halflight, a
bell tolls and a crowd shuffles towards
the old town hall where something
special is about to take place that has
happened hour after hour, day after day
for more than 600 years.
Two small windows swing open and
intricately carved model apostles begin
their slow procession above the square
as the bells ring out. But the true
marvel sits beneath them. An intricate
dial of brass and blue enamel crowded
with symbols. The sun, the moon,
constellations marching in log. And
below that, another great wheel showing
the saints days and seasons of the year.
For six centuries, the old astronomical
clock has tried to tame the most elusive
thing humans have ever tried to measure:
time. It has outlasted fires, floods,
plagues, empires, and the artillery fire
of Nazi tanks. Through centuries of
chaos, this mechanism has kept on
ticking, insisting that time flows
cleanly from one moment to the next. But
what exactly is the clock tracking? What
is time? And more importantly, will it
ever end?
To find out, we return to the clock
itself.
Its great dial is flanked by four carved
painted figures. The astronomer, the
philosopher, the angel, and the
chronicler. Each offers a different
answer to time's most unsettling
questions. And together they form a kind
of council, a medieval chorus presiding
over the true nature of past, present,
and future. And we begin with the
astronomer asking him a simple question.
What lies ahead for the universe? Will
the cosmic clock continue to tick
forever? Does an infinity of tomorrow's
stretch out before us indefinitely?
When the Oloy clock was built, many
origin stories were being told around
the world. A six-day creation, the
biblical garden of Eden. And in the
East, Hindu, Buddhist, and Jane
teachings spoke more of repeating
cycles, often with no absolute
beginning. However, today standard
cosmology argues that time doesn't
stretch back infinitely far into the
past. Instead, there was a definite
start. The moment the universe took its
first breath, the big bang around 13.8
billion years ago, space and time
simultaneously flashed into existence as
the newborn universe expanded rapidly,
and it's been expanding ever since. And
so the secret to unlocking the
universe's future and the question of
whether time is indeed infinite lies in
deciding what will ultimately happen to
this expansion. And one man, an
overlooked giant of 20th century
cosmology, was amongst the first to
consider this idea in detail. What will
be the ultimate fate of our universe?
His name was Richard C. Tolman.
Tolman's career is a study of two
parallel paths. A quiet, fiercely
intelligent, practical man whose first
love was the search for scientific
truth, but whose unique skill set made
him invaluable when geopolitics brought
the world to war. In the First World
War, Tolman joined the Chemical Warfare
service, and by the Second World War, he
was advising the Manhattan Project on
how to build the atom bomb. But before
the bomb, Tolman quietly became one of
the world's foremost experts on Albert
Einstein's general theory of relativity
at a time when it was still largely
unfashionable. 12 years before, the
Soviet physicist Alexander Freriedman
had shown that Einstein's equations
permit a universe that initially expands
but then reaches a maximum size before
recolapsing back down to nothingness.
But in a landmark 1934 paper, Tolman
showed that such a collapse wouldn't
break any of the sacrosan laws of
thermodynamics.
He showed that the eastern ideas of
repeating cycles were also possible. An
endless oscillation of expanding and
contracting universes.
Tolman legitimized the possibility of
these collapsing phases, an idea known
today as the big crunch. In such a
cyclic universe, time may not be
infinite. Instead, the cosmic stopwatch
would regularly be reset back to zero.
Although the trouble is, we don't seem
to live in such a universe. And the
story of how we came to discover this
begins with a simple question.
How do we measure distances?
Astronomers often use objects known as
standard candles as cosmic keyard
sticks. These are objects that all share
the same inherent brightness. If we look
up at the night sky and see dimmer or
brighter ones, the dimmest must be the
furthest away. Cosmic explosions known
as type 1A supernovi are particularly
powerful standard candles. They detonate
when a dead star called a white dwarf
approaches a critical mass and blows
itself to smitherines. Indeed, type 1A
supernovi are so bright that they can
briefly outshine an entire galaxy of
billions of stars and can be seen from
halfway across the visible universe. In
the 1990s, most astronomers assumed that
the expansion of the universe was
slowing down as the initial impetus from
the big bang faded. If true, scientists
realized that this would lead to type 1A
supernovi appearing clear and bright.
After all, they wouldn't be carried away
from us as fast as they once were.
However, two teams studying them found
the complete opposite. The supernovi
were too faint. They'd been rocketed
away from us faster than expected. The
expansion of the universe wasn't slowing
down. It was speeding up. The news sent
shock waves through cosmology. Decades
of assumptions and theories were
consigned to the scrap heap. The big
crunch and the cyclical universes it
could lead to were practically erased
from the textbooks as a possibility for
our universe's future. And in 2011, the
scientists heading up the two teams
shared the Nobel Prize in Physics for
the Landmark Discovery.
This accelerating expansion is usually
put down to a mysterious and shadowy
entity known as dark energy. No one
knows for sure what it is, but what we
do know is what's likely to happen to
the universe if dark energy continues on
its current trajectory unchecked.
Dark energy seems to function as a form
of anti-gravity and appears to be a
property of space itself. And so as it
expands space, dark energy's potency may
only grow, expanding space yet further.
The space between stars could stretch to
such an extent that entire galaxies
would be torn apart. Then the space
between stars and their planets, leading
to the dismemberment of every solar
system. This accelerating expansion
could continue until even the spaces
between the parts of an atom grow
unbearably large. All structure in the
universe would eventually be destroyed.
Astronomers refer to this cataclysm as
the big rip. And in some estimates, it
could reach its crescendo in as little
as 22 billion years time. And if that's
true, the universe is already almost 40%
of the way through its meaningful life.
Indeed, the expansion doesn't just get
faster. It runs away with itself. The
rate of expansion keeps steepening until
the size of the universe grows without
bound, racing to infinity in a fixed
amount of time. You reach a moment
beyond which the equations of general
relativity, the ones that describe the
marriage of space and time, simply stop
making sense, a singularity.
There is no way to continue the story of
the universe past this point. Not just
because clocks themselves would break,
but because there is no spaceime left to
put more time into. In a big rip, the
universe doesn't just end in ruins.
Time itself runs out.
However, this nightmarish scenario is
far from guaranteed. It all depends on
an important cosmological measurement
known as dark energy's equation of
state, often denoted by the letter W.
This is a measure of how strongly dark
energy drives the expansion of the
universe. The more negative W is, the
more the repulsive energy in empty space
grows as the universe expands. And so
time will only end in the infinite model
of a singularity if dark energy's
equation of state is less than minus1.
Only then will the dark energy in each
cubic meter of empty space increase as
the universe expands adding to its
potency and triggering that runaway
surge towards the end of time.
Astronomers refer to this particular
breed of dark energy as phantom energy.
And so what is the value of W?
Unfortunately, it is a far from
straightforward measurement to make.
Instead, astronomers have had to combine
three independent lines of evidence. By
looking at light from supernovi, the
CMBB, the afterglow of the Big Bang, and
the general structure of the universe,
the most recent measurements put its
value at minus1.013.
Yet, while this is technically less than
minus1, it's so close to that value that
it's within a margin of error. In other
words, there is sketchy evidence that
dark energy is indeed phantom, but so
far not enough for the case to be
compelling.
And so, should this calamity be avoided,
what's the most likely alternative?
Well, if dark energy's equation of state
is indeed equal to exactly minus1, we
could be heading for what astronomers
ominously call heat death.
Dark energy will keep driving the
expansion of the universe, but it'll
never run away with itself. Instead, the
universe will be gradually stretched
ever more thinly. Galaxies move further
apart. Matter becomes diluted. Radiation
is stretched and cooled. It is a long
cold unwinding of all cosmic structure.
Star formation will eventually cease as
once great stellar nurseries fade away.
All lights in the universe will flicker
out. White dwarfs, the remnants of
sunlike stars, will fade to black
dwarfs. Black holes will gradually drip
feed their mass back out into the
universe in the form of Hawking
radiation.
Indeed, eventually the universe will
reach an equilibrium so devastating that
nothing new could ever form. Without hot
versus cold, dense versus sparse,
ordered versus disordered, the cosmos
settles into a state of monochrome.
And yet, unlike the big rip, this fate
has no final moment. Time doesn't stop.
Instead, it stretches on and on,
possibly indefinitely.
But an infinite future does carry its
own brand of danger. One that's less
obviously dramatic, but arguably even
more unsettling.
For creatures will appear in that long
night. Specters will flicker out of the
black. Paradoxes that strike at the
heart of our understanding of why time
has a direction at all. These are
mysteries beyond the expertise of the
astronomer alone. They are questions
only the philosopher can truly answer.
As Big Ben chimes, fireworks tear into
the sky above the river temps.
Rockets cascade in shoots of purple and
red. Golden sparks sizzle and crackle.
But then something strange happens.
The trails of light suddenly converge.
The sparks gather themselves back
together. The fireworks unexplode.
Fireworks are key to the way we mark the
passage of time used to celebrate big
milestones in the collective calendar.
But of course, we've never seen one in
reverse. This may seem like common
sense, but to a physicist, it's quite
strange. This is because the equations
describing motion, forces, and therefore
fireworks work equally well either way.
There's nothing in the laws of physics
to prevent fireworks from unexloding.
So why do we never see it? Why does time
always seem to run forwards?
The man who found the answer to this
riddle was Levik Boltzman, a 19th
century physicist who saw the universe
as a grand casino where the house always
wins and time marches inextricably on.
To understand Boltzman's big idea,
imagine a brand new deck of playing
cards.
All the cards are arranged in numerical
order within their suits. Now, imagine
accidentally knocking the deck off a
table so that the cards cascade
haphazardly onto the floor. Then, one by
one, you randomly gather them back up
again. There's nothing to stop you from
striking lucky and collecting them all
back in their original order. It's just
ridiculously unlikely to happen. There
is, after all, only one specific way to
do this. There are an awful lot of
alternative configurations.
How many exactly? almost 100 unicilion.
That's a one followed by 68 zeros.
That's about the same as the number of
atoms in the Milky Way.
In other words, the chances of the deck
randomly returning to its original state
are the same as picking out a particular
atom at random from an entire galaxy.
And indeed, by thinking about atoms
themselves in a similar way, Boltzman
explained why time always appears to run
forwards.
When it comes to time, physicists often
talk about entropy. It's not the perfect
description, but entropy is loosely a
measure of how disordered a system is. A
brand new deck of playing cards is a
highly ordered system. In other words,
its entropy is low. There is precisely
one way to return the deck to this low
entropy state. And there are 100
underscillion ways for the deck to
become more disordered for the entropy
to increase. So it's not that an entropy
decrease is forbidden or impossible.
It's merely that it's very unlikely to
happen. And on average, you'd have to
wait an extortionately long time to see
it happen. Given our short lifetimes and
the relatively short period of time the
universe has existed so far, we never
do. It's perfectly possible for the
atoms within a firework to conspire to
make it unexplode, but don't bet on it
happening anytime soon.
And so, according to Boltzman, it's the
fact that the probabilities are so
heavily stacked in favor of an entropy
increase that gives time a direction.
The English astronomer Arthur Edington
later described this direction as time's
arrow. Time for us only ever points
forwards in the direction of disorder.
And if time continues to run forwards
indefinitely, then the future may well
be infinite. And indeed, this isn't just
a theory. Modern experiments have tried
to catch entropy running backwards. The
clearest example comes from something
called nuclear magnetic resonance, where
physicists work with trillions of atomic
spins, the equivalent of tiny bar
magnets hidden inside matter. Left to
themselves, these spins behave like
spectators drifting out of a stadium.
They spread out and lose coordination.
But with a carefully timed sequence of
pulses, you can force them to turn
around and refocus.
But just an instant, the crowd comes
back into alignment. It looks like the
system has partially rewound itself. A
brief engineered reversal of disorder.
But the effect is shockingly fragile.
any stray interaction, any imperfection
in the pulse sequence, even the tiniest
uncontrolled vibration destroys the
reversal. The moment you stop actively
shephering the system, the natural drift
into disorder resumes.
And this same pattern shows up in more
modern quantum simulators with trapped
ions or ultra cold atoms. In principle,
the microscopic equations allow a
rewind, but in practice, reality never
cooperates for long.
This may seem like a triumph for
Boltzman's theory, but his work still
contains a hidden assumption, one that
someone very close to him spotted almost
immediately. His former teacher, Joseph
Loid, pointed out a brutal flaw.
Imagine that instead of a pristine,
perfectly ordered deck of cards, you
start with one that has been thoroughly
shuffled into maximum randomness. Now,
drop that pack of cards onto the floor
and pick it up. This time, most of the
outcomes are more ordered than what you
began with. Entropy would decrease and
the arrow of time would point the other
way. In that world, it would be
exploding fireworks that seemed
bizarrely unlikely. And so, Boltzman's
explanation only works if you assume the
universe, like a card deck fresh from
its packet, began in a very special,
highly ordered state. But the laws of
physics don't demand that. They work
perfectly well from any starting point,
even ones that would make entropy fall
rather than rise.
And this became known as Loit's paradox.
Loid's point was devastatingly simple.
If you don't assume a special beginning,
you don't get a special temporal
direction. Loid had shown that there's
nothing in the laws of physics to force
time to run forwards. If the equations
work equally well in reverse, the
universe without a special beginning
could just as easily drift backwards.
But even that wasn't the deepest
problem. Feloshid had shown that the
arrow wasn't guaranteed. But he hadn't
actually explored how an eternal
universe would behave. That breakthrough
would come from Henrikare. And with his
work, we would begin to question the
very structure of time in an eternal
cosmos.
In 1890, Pankare published a landmark
paper, the three-body problem and the
equations of dynamics.
Lo had shown that nothing in the laws of
physics forbids time from running
backwards. Wangare now went further,
proving a remarkable theorem. He showed
that in any finite system obeying
reversible laws, those reversed states
are not just possible, they are
inevitable. Given enough time, the
system must eventually return to
configurations arbitrarily close to ones
it has visited before. This meant that
if the future was infinite, the universe
would be guaranteed to loop back on
itself. Not by destiny or design, but
simply because a finite cosmos can only
reshuffle its contents in so many ways.
Eternity would eventually force every
combination to return. The same stars,
the same planets, the same galaxies
seemingly risen from the dead. In
Quankare's universe, this repetition is
mathematically unavoidable. Even more
certain the night following day. Taking
into account the size of the universe
and the amount of things in it, its punk
array recurrence time is roughly 10 to
the^ of 10 to the power of 10 to the^ of
2.08
years, days or seconds. At that scale,
the unit doesn't even matter. It is a
huge amount of time.
And yet, if the cosmos has infinite time
to explore and repeat every allowable
configuration of atoms, then times arrow
and even the notion of cause and effect
begin to dissolve.
And it was precisely this implication
that horrified Boltzman's critics. If
recurrence is unavoidable, then the
entire explanation of time's direction
becomes shaky. The universe would spend
most of eternity in meaningless
repeating fluctuations rather than the
smooth orderly arcs that usually make
physics intelligible. And one man in
particular took aim at this increasingly
fragile account of time's arrow and
Samlo.
Samalo was a human scalpel making a name
for himself by attacking problems with a
surgical precision. And where Loid had
attacked Boltzman's assumptions, Samolo
attacked the consequences. He took
Panker's recurrence theorem and drove it
to its logical end point. If recurrence
is guaranteed in any finite reversible
system, Samillo argued, then entropy
cannot rise forever. In an eternal
universe, entropy must eventually fall
again and again. and not as a rare
exception, but as an unavoidable feature
of infinite time. Lomet had shown that
Boltzman's argument unfairly rested on a
special beginning. Samo now argued that
even if Boltzman fixed that flaw, his
conclusion could never survive an
infinite future. Recurrence would
eventually force the universe to revisit
lower entropy states. And if entropy
sometimes falls, then the arrow of time,
the very thing Boltzman had claimed to
explain, cannot be derived from the laws
of physics. It collapses the moment you
give the universe infinite tomorrows. In
a sense, Zerlo was questioning whether
before and after can have any absolute
meaning in an eternal universe. And this
is where the astronomer completely bows
out. What follows next belongs purely to
the philosopher.
Because mere months before Boltzman
published his ideas about the direction
of time, one man had already followed
its consequences to their most
unsettling end. A political prisoner who
realized that if time is infinite and
the universe finite, then the cosmos
must contain not only repetition, but
endless copies of you. Smoke
hangs low over the Parisian streets. In
the Rousonteni, students and workers
hurl stones at the municipal guards. And
amid the chaos stands a thin, determined
22-year-old Louis August Blanke.
Suddenly, he takes a bullet to the neck
and collapses to the ground. However,
Blonnie survives the ordeal. And indeed,
he would be injured three times that
year, 1827, protesting against the
restored Borbin monarchy. A full-blooded
revolutionary socialist, Bli would later
be sentenced to death for his part in an
1839 insurrection. His punishment
subsequently commuted to life
imprisonment. He would escape only to be
recaptured and then released once more.
In total, Blonkey spent over 35 years of
his life behind bars.
Or should that be this version of his
life?
In 1871, Blony found himself a sole
inmate at Fort to Tao, an island prison
overlooking the Bay of Mole. Each day,
the waves returned to batter the walls
exactly as they had the day before.
Alone in that repetition, Blony began to
wonder whether the universe might be
doing the same. endlessly replaying
itself again and again.
And Boni's prison ruminations became a
book, eternity according to the stars.
He'd been inspired in part by his view
of human history. He believed that
history was doomed to repeat because
there were only so many options.
Eventually, the same events are fated to
reoccur. Along Key was also an armchair
astronomer, acquainting himself with
star cataloges and tales of sprawling
nebula and distant cosmic systems. And
so amid the isolation of his island
prison, he fused these two ideas. His
book describes a universe made from
finite materials endlessly rearranging
into familiar patterns across the
heavens. Every human being is thus
eternal in every second of its
existence. What I write here in my cell
at the fort of Taro, I wrote and will
write under the same circumstances for
all of eternity.
In other words, you are but a collection
of atoms. Given enough time, the
universe will conjure exactly the same
atoms in an identical configuration. Not
only that, it will do this over and over
again. In a universe with infinite time,
you were guaranteed a form of
immortality.
And perhaps above all others, one
philosopher explored how it might feel
for your life to repeat endlessly for
eternity.
Friedrich nature.
What if a demon were to steal into your
loneliest loneliness and say to you,
"This life as you now live and have
lived it, you will have to live once
again and innumerable times again, and
there will be nothing new in it. But
every pain and every joy and every
thought and sigh and everything
unspeakably small or great in your life
must return to you all in the same
succession and sequence.
And so what if every moment of your life
must return again identically for all
eternity? Would you curse that fate or
embrace it?
All of this leaves us in a peculiar
position. Indeed, not everyone could
live with a universe that loops without
end. But for one figure, the prospect is
particularly repugnant. For we now turn
to the angel. What do they see when they
look into an eternity that never lets
anything die?
And the angel which I saw stand upon the
sea and upon the earth lifted his hand
to heaven and swore that there should be
time no longer.
In the silence of the cyine chapel, the
scaffolding caks.
A small oil lamp throws a trembling
light onto fresh plaster as Michelangelo
Broneroti lifts his brush. He's in his
60s now, grayed and wrinkled by the
relentless passing of time. Indeed, it's
been nearly 25 years since he painted
the famous ceiling of this room hidden
away inside the Vatican. Back then, he'd
illustrated the moment God first sparked
life into Adam. But now, his attention
is turning towards the end of time.
Eventually, Michelangelo sets down his
brush. After four long years, this
latest project is finally finished.
Taking up the entire altar wall of the
cyine chapel is the Renaissance master's
depiction of the last judgment. Jesus
has returned to the earth in final and
eternal judgment of humanity. The dead
are stirred from their graves, their
morality weighed. Some ascend to heaven,
others descend into hell.
And so in Michelangelo's universe,
earthly time does not loop. It does not
repeat. It ends. And when it does, every
act is tallied. Every choice has weight
because it will never reoccur. You have
but one shot at piety.
Religious scholars and philosophers call
this idea esquetology, the science of
last things. Esquetology is a common
feature of the Abrahamic religions.
Christianity's book of revelation,
Islam's Kyama, and Judaism's Yamhadim
all imagine time flowing towards a
singular irreversible end point where
justice is finally dispensed and history
is allowed to close. The esquetology of
cyclical Eastern religions is a little
different, but still present. Take the
Hindu tradition in which the present age
ends when Khalki, the final avatar of
Vishnu, arrives to stride a white horse
to bring the Ki Yuga to a close after
which the cosmos is renewed and the
great cycle begins again. And so in
these worldviews, time acquires meaning
only because it finishes.
Modern cosmology, however, is far less
merciful.
Indeed, Bronkaway showed us that in a
universe with infinite time and only
finite ingredients, nothing is ever
truly finished. Given enough time, the
atoms that once formed your body must
assemble again in precisely the same
configuration. And so, somewhere in the
far and infinite future, the dead will
rise, not because a god has summoned
them for judgment, but because the
church of statistics demands it. the
same bodies, the same thoughts, the same
sins.
Every moment will reappear. Every
kindness, every cruelty, every betrayal,
every mercy, and then it will do so
again and again and again, spooling on a
neverending tape.
But in a universe where every life is no
longer lived just once, how can there be
judgment? After all, your actions are
predestined, doomed only to repeat. In
such a world, morality itself
evaporates. To the angel, this is
blasphemy. Just one of the things that
horrifies it about infinite time. And
indeed, in terms of horrors, that is
just the beginning.
A heat dead universe is extremely
dilute.
Any remaining matter is spread wafer
thin. The universe's temperature
approaches an unfathomable low. Space is
almost completely empty.
Almost.
We will still contain quietly
fluctuating quantum fields. Even heat
death cannot calm them completely. In a
universe with a low but finite
temperature in infinite time, every
possible quantum fluctuation will
eventually occur. Even Boltzman
fluctuations.
These are spontaneous random rises of
order out of disorder due to an
improbable but possible rearrangement of
the microscopic realm. Of course, most
of the time these fluctuations will lead
to small changes. a brief increase in
the density of matter in a small part of
space, a temporary photon, a momentary
particle antiparticle pair.
But occasionally in an infinite
universe, larger fluctuations are bound
to occur. And the most famous example of
this is perhaps the most disturbing
prospect of all. A Boltzman brain,
a fully working mind temporarily
assembled from the chaos by chance. A
fleeting consciousness complete with
memories it never lived. Counterfeit
thoughts, feelings, and emotions. A fake
sense of self floating in the eternal
void, existing for a split second, then
lost to the black.
And so now the question is statistically
which is easier to pull off? A temporary
consciousness summoned by chance quantum
fluctuation or one that's the child of a
real brain sculpted by billions of years
of evolution on a planet that needed
billions more years of stars making
heavy elements from which to build it.
The grim truth is that the more time
there is, the more the vast majority of
conscious experiences will belong to
Boltzman brains and not biological ones.
Indeed, in a universe that lasts
forever, it becomes dramatically more
likely that you, the you experiencing
these words right now are one of those
fluctuations.
Ordinary beings born from stars and
shaped by genuine histories become the
rare exception. To quote Carl Sean, "If
you wish to make an apple pie from
scratch, you must first invent the
universe." And so perhaps it would be
easier for one to simply appear from
nowhere.
And so, do you actually exist?
Are you sure? Or is the world you see
around you a mere figment of quantum
eternity? These thoughts may be enough
to trigger an existential crisis, but
the situation is far worse for the
angel. How do you weigh actions taken by
a mind that has only existed for a
moment? How can you judge a life that
was never actually lived?
An eternal universe becomes not a place
of judgment and reckoning, but one where
endless consciousnesses drift unmed
through statistical noise beyond the
realms of morality. And infinite time
does not stop there. Anything that can
happen will. Ghost planets complete with
mountains worn smooth by fictional
erosion, hiding fossils within them from
creatures that never lived. all
illuminated by light from stars that
never burned. Even entire galaxies and
universes would be summoned from the
statistical fog. Nothing forbids these
configurations. They are only wildly
improbable. But of course, the notion of
wildly improbable collapses under the
weight of infinite time.
And so only a universe with a real
ending can avoid these specters and
comfort the angel. If time ends, truly
ends, bonker loops die, falseman brains
are limited, moral action regains
weight, and judgment becomes possible
again.
And yet for the angel, that is still not
the end of the danger. There are more
quantum devils lurking in the shadows,
and perhaps none more bizarre than the
prospect of quantum immortality.
In a windowless room, a volunteer sits
hunched over a cold metal table.
In front of him is a big red button.
Through the tanoi from a neighboring
room, an anonymous technician explains
that the button is harmless.
The anonymous technician is lying. for
pressing the button triggers the quantum
measurement of an electron. Electrons
have a property called spin that can
either be up or down. It's the quantum
equivalent of a coin toss. Chances are
50/50. If the outcome is up, a poison is
released into the room and the volunteer
dies. If the outcome is down, the poison
isn't released and the volunteer
survives. Nothing happens and the man
lives to press the button another time.
Thankfully, of course, this is only a
thought experiment, but the fact that
the outcome hinges on a quantum
measurement could lead to a truly
uncomfortable situation for the angel.
In a classical non-quantum universe, the
volunteer will always die eventually.
Assuming he continually hits the button,
after 100 presses, the odds of survival
are just 1 in a million trillion
trillion. But the introduction of a
quantum measurement may change those
odds. For there is one version of
quantum physics that paints a
significantly different picture. The
many worlds interpretation.
It says that whenever the universe faces
a 50/50 quantum choice, it splits into
two copies of itself. Both outcomes
occur just in two different branches of
reality. Clearly, your consciousness can
only continue in branches where you
don't die. If the electron spin is up,
your consciousness would immediately
cease. But there's always another
reality where the outcome was down. And
that's the only branch in which your
consciousness can logically go on. And
so after a 100 button presses, there's
guaranteed to be one version of you that
survived them all. Even though you died
in all the other branches. In other
words, if your life hinges on a quantum
measurement, it is impossible for you to
die. There will always be a version of
you that survives even a million button
presses. You are effectively immortal.
Immortality without moral weight
destroys everything the angel stands
for. In a universe that contains
infinite branching over infinite time,
every conceivable crime and moral
indiscretion is committed. Virtue didn't
save you, and vice didn't doom you.
Moral courage is worthless. Moral
cowardice unpunished. Even death loses
all meaning because you always escape it
somewhere.
However, not everyone buys this idea of
quantum immortality. Most physicists
don't. This is because it depends
entirely on a specific reading of
quantum mechanics. The many worlds
interpretation for which there's still
no experimental evidence. Nor has any
experiment ever confirmed that
consciousness tracks only the surviving
branches. And so perhaps this really is
a step too far into eternity.
The angel's horror is palpable, but its
existential search for an ending also
exposes a deeper uncertainty. We have
spoken as if time were a river that
might speed up, slow down, bend, or
finally run dry. The angel has to
believe in such a river because judgment
requires both a beginning and an end.
But not everyone agrees that time flows.
Some claim that the river is frozen,
that every moment, past and future
already exists.
If so, time cannot end because it never
truly began. And on the alloy clock, one
figure knows this better than anyone.
The chronicler doesn't measure time. He
records it. All of it. And in his book,
every page is already written.
A vast parchment lies unfurled on a
vintage mahogany table.
The paper is disheveled, its surface
discolored. At first glance, it looks
like an antique world map, but the
labels look out of place. Rome, the
eyides of March. London, the great fire.
Philadelphia, declaration signed.
Hiroshima, the first flash. New York,
falling towers.
The distances make no sense. Hiroshima
sits closer to New York than Rome does
to London. And that's because this isn't
a map of where things are, but when
things happened, a map of history, not
geography. The map is the work of the
chronicler. But he has a secret that is
hardly ever shared. The map is already
finished. He doesn't need to add new
events as they occur because there are
no new events to record.
On a map of the earth, there's no new
terrain to add. It's all there in its
entirety. Flying from Sydney to London
doesn't mean the Australian city
suddenly disappears. Nor does London
magically materialize only as the plane
begins its final descent. All locations
on Earth exist alongside one another, no
matter where we happen to find ourselves
on the map. And this is also the case
for the map of time. Every moment, past,
present, and future, is already there.
These events are simply different
locations on the same vast temporal
terrain. And so this means that on the
map of time, standing in the present
doesn't make it any more special than
standing on the Greenwich meridian. The
present may be a useful reference point,
but it's merely another moment. All past
and future events exist fully and
completely.
This idea known as the block universe is
based on Albert Einstein's theories of
relativity. And to understand its
implications, picture a simple loaf of
bread.
In our everyday lives, time seems like a
series of consecutive moments. Those
moments are like slices of the bread.
Tomorrow dawns and a new slice is
somehow added to the loaf. But the block
universe theory argues that the loaf is
already fully formed. Slices can never
be removed. Meaning yesterday doesn't
simply vanish. The past is still there
in its entirety. But then no new slices
can be added either. The whole of the
future is there too. Every bit as real
as the slice we call today. If you could
see the loaf from the outside, it would
look like one vast unchanging block.
Hence the name of the theory.
And if that's not unsettling enough,
Einstein's relativity does not merely
say that different observers see time
differently. It says that they move
through it differently, too.
Each observer traces a path, a world
line through the block. Along that path,
events appear ordered. Cause precedes
effect. Entropy rises. Time seems to
flow. But the arrow of time is not
written into the block itself. It
belongs only to the path.
This means that for someone on a very
different world line, what counts as
past and future would be rearranged.
Our tomorrows could be their yesterdays.
This perspective dramatically reframes
the worries of the astronomer, the
philosopher, and the angel. They feared
what lies ahead. But here, ahead is
nothing more than a local illusion. From
another vantage point, the things they
dread have already happened or never
happen. In a sense, the trio are arguing
over the length of a river that may not
exist as a river at all. to the
chronicler. There is no gradual
unfolding, no countdown, no approaching
catastrophe. There is only a completed
map.
Einstein's general theory of relativity
is arguably our best, most
scientifically verified theory of all
time. It underpins the blocky universe,
but it's not the only show in town.
Quantum mechanics is the other towering
pillar of modern physics and the two are
famously hostile bedfellows. At the
heart of this discord is a fundamental
disagreement about the nature of
reality. Try and combine the two
theories together and the equations
quickly crash into an avalanche of
infinities. But back in the 1960s, two
men tried to circumvent this problem by
attempting something wildly ambitious.
writing down a single equation that
describes the entire universe.
It all started in 1965 when physicists
John Wheeler and Bryce Dit met in Rally
Durham airport when Wheeler was waiting
for a connecting flight. Between them,
the pair would eventually write down
what is now known as the Wheeler Dwit
equation. And this equation is
remarkable, but not for what it
contains, but for what it doesn't.
There is no mention of time.
Usually time is an indispensable part of
a physics equation. It describes how
variables change. But in a sharp
disturbing contrast, the wheel the dowit
equation does not describe a universe
that evolves in time. It describes a
universe that exists all at once. No
ticking, no evolution, no before and
after. The universe at its deepest level
seemingly simply is.
The astronomer worried about how long
time will last. The philosopher was
concerned about the ramifications of
infinite time. The angel feared what an
endless future would bring. But the
block universe and the wither toit
equation suggest that there is no future
waiting to happen. Something the
chronicler already knows.
This begs an unavoidable question. If
the universe is a completed map, why
does it feel as though we're constantly
moving across it? Why does there seem to
be a present moment at all?
To answer that, theoretical physicist
Julian Barber takes the Wheeler Dowit
equation more seriously than almost
anyone else. Where most physicists treat
the absence of time as a technical
nuisance, Barber treats it as a
revelation, his claim is stark. Time
doesn't need to exist, not even as a
hidden dimension beneath the surface.
According to Barbara, reality is not
something that unfolds. It doesn't
progress from past to future. Instead,
he proposes that the universe consists
of a vast collection of individual
timeless configurations he calls nows.
Nothing moves between these nows. There
is no cosmic conveyor belt carrying one
into the next. No master sequence
ordering them. They simply exist. Once
again, according to Barbara, these
events are not points along a timeline,
but places on a map. And crucially,
there is no rule that says we must ever
arrive at them.
On a real map, both Paris and the Sahara
Desert exist. But standing in Paris does
not make visiting the Sahara inevitable.
The existence of a Boltzman brain
elsewhere on the chronicler's map does
not make it inevitable. Indeed,
inevitability requires time to do the
work. And according to Barber, time
isn't required to exist at all. It only
feels so vivid to us because some now
contain records, a photograph, a scar, a
fossil, memories.
Do the memories inside your brain
require a real past to exist? Strictly
speaking, they only require a particular
configuration of neurons now. And so,
can you be sure that the past is not all
in your head?
Julian Barbara's ideas are certainly
radical. Indeed, not everybody is
willing to go as far as saying time
doesn't exist at all. But there is
another approach. One that agrees the
universe is indeed timeless at its most
fundamental level, but then argues time
emerges from the timeless quantum
quagmire.
Imagine a single molecule of oxygen
trapped inside a box. We can talk about
the molecule's speed, energy, or
direction. But asking about its
temperature is meaningless because
temperature does not apply to a single
molecule. So let's zoom out until we can
see a trillion such molecules bouncing
around the box. Some are fast, some are
slow, some collide with each other. But
it's now incredibly difficult to track
the motion of every molecule. And so
instead, physicists have invented the
concept of temperature as a shortcut. It
is a measure of the average kinetic
energy of all the molecules. Temperature
is not a property of individual
molecules. It is a statistical summary,
a way of talking about a system without
knowing every tiny detail.
It is the story we tell about what's
going on above a certain scale.
And for physicist Carlo Ralli, this is
the way to think about time.
He proposes that individual quantum
events don't unfold against an external
ticking clock. At that scale, reality is
timeless. Like temperature, time is the
story we tell to make sense of events
only as things get bigger as multiple
quantum events interact.
In this vision of the cosmos, time is
not a thing the universe contains, but
merely a tool we use to describe the
universe once it becomes complicated
enough. Physicists call these kinds of
things emergent. Time and temperature
not existing at the most fundamental
level of reality, but eventually
emerging as a result of complicated
interactions.
In a sense, it's like your heartbeat.
Zoom in on your heart with a giant
microscope and you'll see individual
cells and maybe even individual atoms.
These atoms and cells are not beating.
The thing we call beating only emerges
as multiple cells work together.
If time is similarly emergent, then
asking whether time can end is like
asking whether temperature can end. It's
a question that suddenly sounds like
complete nonsense.
And so we're left where we began,
staring into tomorrow and realizing we
don't know what kind of thing it is.
Perhaps it's a real destination, waiting
somewhere ahead with heat death and its
statistical ghosts lurking in the far
distance. Or perhaps it isn't ahead at
all. Perhaps tomorrow already exists or
never will or exists only as a
convenient story told by creatures like
us, moving through a universe too large
to hold in one mind. Either way, the
future remains an open question. For
now, there is only this moment, the one
we are living inside.
tell us what you think. Thanks for
watching and we'll see you next time.