One second of time.
That's it.
You just had one.
Who decided how long that was?
If you think of it objectively, this
doesn't actually mean anything.
It's a pretty arbitrary duration, right?
Yet, even though it's arbitrary, we
made it very precisely arbitrary.
One second is not just one second.
It's 9,192,631,770 microwaves of radiation coming off
of a cesium 133 atom inside of an atomic clock.
And there are many of them all over the world.
And still, why?
Where did they come from?
Why not round up to 10 billion or down to 9 billion?
Because time is something we invented.
It doesn't actually exist.
I mean, well, it's a debate.
And that's what we're going to talk about.
Have you ever sat around and thought about time?
Not just like the time of day, like the sun
moving and stuff, the moving of the planet or the stars,
just time.
What is it?
Why is it?
Who decides how fast it moves?
How long things will be?
What is time?
Where does it come from?
Is time even actually real?
Or is it just how our brains process
this complicated and strange reality we all exist in?
We're going to tick through all these tocks.
So welcome to Uno Dos of Trace.
Every month I pick a topic, and I dig deep into it.
Breaking it into chunks so that we all understand it
a bit better, myself included.
I'm no expert.
This month, we're talking about time.
Over the next five episodes, we're
going to dig into the history, the engineering, the psychology
and relativity, the philosophy and physics, even
the whole universe, and the end of time.
Let's kick into it.
Hi, hi, hi, Trace here again.
First, my fellow time lords, what is time?
Rene Descartes and Emmanuel Kant, 100 years apart,
both had philosophies of time.
And one said quote, "we do not appreciate time objectively
as a physical thing, that it is simply
a pure form of sensible intuition",
which actually isn't that far off from what physicists today
think.
That it has to do with how we perceive
and not necessarily something objective.
There are lots of philosophers and physicists
and mathematicians and psychologists, all who
have attempted to define time.
Think of it like the association in memory
of successive perceptions, mathematical concepts,
physical motions, like gravity, energy, or heat.
They're all connected to time.
But perhaps, that's just how our brain interprets
what's already there.
Because time is fluid.
So I'm going to answer the title question now.
Time is a construct that we built
to help us better understand the increasing
complexity of the universe and its changes.
And whether time is flat, and it already
has all happened, like a DVD, a flat circle.
I know it's a joke, but seriously, that's
one of the ways to think about it.
Or whether we're creating time as we go remains to be seen.
And we are going to talk about both.
But time isn't a particle or a wave.
It isn't a mass.
But it might be affected or created by some of those.
OK, so anyway, let's just go back.
What is time?
Time is what we think it is.
So what do you think it is?
Let's do the five Ws-- what, where,
when, why, and of, course how.
What is time?
The dictionary definition of time
is the indefinite continued progress
of existence and events in the past, present, and future,
regarded as a whole.
The etymology of the word time comes
from old English and Proto-Germanic, old Norse,
and Swedish.
You could say tema or timon or timme, or temay,
coming from to divide.
Time is experienced.
Yes, sure, you can see the sun and the stars move.
You can see the rotation and orbit of our planet.
You can see things age and die around us.
In that respect, time is very much real.
But it's also kind of not.
Time isn't really anything.
There is no like big cosmic counter
that's counting down to the end of time
or up from the beginning.
Time isn't a thing at all.
If it's real, it must exist somewhere.
But there is no particle that determines time,
at least not that we know of.
So where is time?
We know that it is out there.
Radioactive decay is done over time.
There was something, now there isn't something.
The stars and the galactic ephemera all move.
Time is required to calculate those movements
and those decays.
Energy moves through the universe.
Without time, there's no way to say
when something was emitted and then absorbed
or at least not accurately.
And you are watching this.
And the Earth moved like 110,000 kilometers in that time.
Atoms, they decayed.
They vibrated.
Your screen emitted light that was then absorbed by your eyes.
Time, in this respect, is real, and it's measurable.
But it's also not.
I know it's so confusing.
At least not in the way we think.
So let's assume that time is a thing
and that time is real and measurable because we
can do both of those things.
But now, we get to the fun questions.
How did time start?
How is time?
In a 1996 lecture, "The Beginning of Time"
by Dr. Stephen Hawking, he said, quote, "all the evidence
seems to indicate that the universe has not
existed for ever, but that it had a beginning
about 15 billion years ago".
He liked to relate that time is sort of like the south pole.
There's nothing south of the south pole.
The idea, of course, being that south with something
that we invented.
And that a south pole is also something that we invented.
But because we have time, we had to have a start.
And so that would be the Big Bang, right?
That idea alone, what he just said by the way,
is remarkable today.
We take it for granted that time has a beginning.
We know when that beginning was.
It was about 14 billion years ago.
But at some point in human history,
we had no idea when time started.
We just knew that time existed.
And it was continuing to flow around us all the time
like a rock in a river.
We just knew that there was a river.
We didn't know where it started.
We didn't know where it went.
And honestly, even though now we sort of know
where the river comes from, we still
don't know where we're going.
At some point, thought many, a deity
flipped on the light switch, or perhaps the Big Bang happened.
And at that moment, time began.
Again, the Big Bang.
Of course, the Big Bang singularity
is separate from the Big Bang the event.
The event is what we're talking about.
The singularity is still up for debate.
The idea that all matter in the universe
was a single point, not actually matter,
like all of the infinitely dense point of everything
that exists-- energy, matter, everything, all of it.
No atoms or particles, just the energy
of the universe in one infinitesimally small spot,
that is still debated.
But that is the Big Bang singularity.
The event itself we're pretty sure that that happened.
At least in some capacity there was massive inflation
all at once.
And someone gave that universe a laxative.
And all of a sudden, boom.
We've cut the universe.
And it expanded faster than the speed of light
for a little bit.
And now, we see the result, which
is all of this energy and all of this matter
in the universe moving, inflating, moving away
from each other.
The energy is moving.
The galaxies are moving away from each other.
The universe is expanding.
It's called inflation.
And we can see light from the earliest universe.
It's still out there.
The very edges of everything permeating everything.
The microwave background radiation
scattered by the matter of the universe in every direction
that we look.
And this is in part how we know when time started.
Because we know the speed of light.
And we know how big the universe is, or at least the inflation
speeds.
So we can kind of calculate roughly
how long it's been doing that.
And from this, we can imagine time sort
of like the surface of the Earth.
Time has no edges, no boundaries.
There's no inner edge of the expanding
balloon of the universe.
It just goes.
And it's not expanding into anything.
It's just happening.
So imagine if you're on this planetary surface
that I've just invented that is time,
and you start moving through time.
You're walking along the surface.
Unlike a real surface, you never come back to where you started.
It's imaginary.
But time just kind of goes and goes and goes.
And the Big Bang, like the south pole, started time.
That's maybe where you began.
But the universe keeps it going because the universe is
getting less ordered.
If you imagine the universe right
before the Big Bang was this kind
of infinitesimally small spot with no particles,
it was extremely ordered in some ways.
And now, it's getting more disordered, more messy,
more scattered.
And that disorder can be tracked.
It's called entropy.
But you have to track it, of course, over time.
And that's where we get to the second law of thermodynamics,
which is one of the things that physicists
think is driving time.
The arrow of time is essentially that there
is more entropy in the universe today than there was yesterday.
We can't track all entropy everywhere,
so it might be local to us.
But what we do know is that it is happening.
So that's one way to measure time.
But that doesn't necessarily mean that is time.
It's just a way to measure it.
So why does time exist?
Because it does.
On some level, we humans create time.
But time also exists inherently.
There's no like if a tree falls in the woods,
and you're not around riddle in my head for time.
You know?
Time still happens, regardless of our selfish human
perspective in that it's a measurable thing going on
in the universe.
If we were wiped out, would time cease to exist?
I mean, by our reckoning, sure.
But by universe reckoning, probably not.
Again, I'm not an expert, so if you disagree, please let me
know in the comments.
But if time did not exist, then everything
would be happening at once, which some physicists think
is how it is.
Some scholars believe time exists because space exists.
One of those is, of course, uncle Albert Einstein
from the 1910s.
And he connected time as a part of space.
So imagine a movie, the drama, the excitement,
the narrative flowing, laid out, you experience it
from beginning to end.
That is not unlike time.
Now, imagine a DVD of that movie.
It's flat, readable.
Everything in the movie is right there.
You could just look at it if you knew what you were looking at.
Both of those are valid perspectives of time.
We can experience it linearly, like a narrative,
watching the movie as it plays out.
But we can also look at it from above,
or from a different angle and see all of time, everywhere,
and the whole story.
Because time is part of space.
In physics, spacetime is a mathematical relationship.
It's physical.
It's measurable.
It's quantifiable.
Things with high mass end up distorting and warping
spacetime.
And fast things experience time differently than slower things.
And we're going to get to that in a little bit.
We're still like in the first episode, OK?
We're still just doing that right now.
So when is time?
This is a question actually that I love.
As soon as I started researching it, I'm like, when is time?
When?
When is now?
Because, technically, now was then.
By the time I said now or even thought now, time had passed.
By the time I thought now and the time that I said now
and by the time you heard now, now was not the same thing.
Think of like a phone call where you call your friend
across country.
You can say out loud, can you hear me now?
And they say, yep.
But now arrived at their ears milliseconds after you said it.
So it's not really the same now, is it?
It's then.
And so now, we're talking.
Literally, now we're talking.
But now, we're not talking.
It was then.
There's no such thing as now.
Or even the time ticks at all.
So much is created by our brains.
Time is about perception, which means
it's about neuroscience and human brains and biology,
three things that I really enjoy,
plus physics and math and astrophysical concepts, which
I really enjoy, and quantum mechanics.
This series is so fun.
So it's all super interrelated and really nuts.
But the main thing is, is time that is experienced.
When it comes to experiencing time,
though, I think that we all know it's felt pretty darn slow
lately, especially in this pandemic.
And that's why I'm so happy to have Nebula
as a creative outlet, even more so now that we've partnered
with Curiosity Stream.
A while back, I really wanted to start making
this series and series like it.
But I wasn't sure if it would work.
I was worried that the algorithm might tank it.
Or that I'd lose subscribers, or I just wouldn't
be able to make it work.
These existential questions haunt everyone
who's creating video online.
Like, imagine being a TikTokker right now.
That's not awesome because there's so much uncertainty.
The great thing is Nebula is a place where
thoughtful creators, like myself, and tons of others
can just make stuff.
They can try things.
We can experiment.
We can enjoy what we do best, which is creating.
I even got to call up Andrew Smith from the Great British
Baking Show and talk about the science
of baking for an original series called Working Titles.
And it airs only on Nebula.
And it was so fun.
And it was such a breath of fresh air for my creativity.
And I think you're going to love it.
I mentioned Curiosity Stream too because they love Nebula.
They love it so much that if you join Curiosity Stream,
you get Nebula too.
And it's actually for a lower price
than joining Nebula alone.
On Curiosity Stream, I can get documentaries
about space and technology, AI and futurism,
of course, climate change and animals, and even the internet.
Curiosity Stream loves Nebula so much that for a limited time
they are offering 26% off of all their annual plans, 26% off.
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We fact checked it.
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And you're supporting creators that you love.
And you can listen to like David Attenborough narrating tales
about hummingbirds.
And Chris Hadfield taking you on a road trip
through the universe.
You can watch a Gen Zer learn about Limp Bizkit over a nebula
for the first time.
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And then go back to Curiosity Stream
and watch a show about big data or about the internet.
To get all of this, you can use the link in the description.
It's so easy.
Curiositystream.com/trace.
Link down below.
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That's right.
All of the episodes as one giant mega episode on Nebula
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So curiositystream.com/trace, promo code Trace.
26% off for the year.
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Thanks for considering it.
I really hope that you find it a valuable service.
I think you will.
Let's go back, though, to the science of time.
Honestly, I think this series might have
broken my brain a little bit.
I think I said now like 45 times.
I don't know.
Hey, I'm just here for y'all.
So come back on Wednesday for the psychology of time.
Please subscribe.
I am Trace.
And I will see you in the future.