Okay, so picture this.
You're at a crossroads, right?
Like a big decision, a job offer,
or maybe like something huge, life altering.
Yeah, yep.
In one reality, you jump in head first,
but in another, you decide to play it safe.
Now, zoom out for a second.
Imagine every single choice,
every quantum event, even a random coin toss.
It all splits the universe
and makes a new reality for every outcome.
Wow.
That's basically the mind blowing idea
behind the multiverse.
Infinite possibilities.
Infinite versions of ourselves,
making every imaginable choice.
Welcome to Cosmos in a Pod, the space and astronomy series.
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Today, we're diving deep into the multiverse.
What is it?
Why do some physicists think it exists?
What could it mean for our understanding of, well,
everything?
You know, what's fascinating to me about the multiverse
is it's not just science fiction, you know what I mean?
It comes out of some of the most solid theories
we have in physics, like quantum mechanics and cosmology.
And there are different models
of what this multiverse might actually look like.
So it's not just like one giant multiverse out there.
Right.
There are levels, different types.
My head's already spinning.
Absolutely.
You got it.
Physicist Max Tegmark,
he came up with a way to classify these multiverses.
He breaks them down into four levels.
Each level builds on the last one.
And they get more and more complex,
more weird, you could say.
Okay, I'm all about weirdness.
Yeah.
Especially when it comes to the universe.
So level one, the most basic, what's that look like?
Okay, so level one is called the quilted multiverse.
It all starts with the idea of an infinite universe.
Imagine a quilt, right?
Yeah.
With just endless patches.
Each patch is like our observable universe,
a bubble of space with galaxies, stars, planets,
the whole thing.
Now, if the universe really is infinite,
then statistically, every possible arrangement
of matter and energy has to repeat.
Whoa, hold on.
So you're saying there's a patch out there,
an identical copy of our observable universe.
Yeah.
With another me recording this podcast.
Exactly.
That's incredible and also kind of creepy.
Right, and not just one copy.
Think about it.
If space is infinite, there are infinite copies
of you, me, this planet, even this conversation happening
over and over again.
It's like this ultimate cosmic echo.
But you said these are just regions
like our observable universe.
Does that mean in a level one multiverse,
everything's basically following the same rules
of physics as ours?
Precisely.
The basic laws of physics, the fundamental forces,
all the building blocks, those stay the same
in a level one multiverse.
It's just the arrangement of everything that changes,
creating these different cosmic landscapes.
Got it.
So level one, infinite repetitions
of regions like ours.
What about level two?
Does it get weirder from here?
Oh, level two is where things get really interesting.
This is called the inflationary multiverse.
It comes from the idea of cosmic inflation.
I remember learning about cosmic inflation.
It's that idea that the universe expanded
way faster than the speed of light for a tiny fraction
of a second right after the Big Bang.
Exactly.
But how does that lead to a multiverse?
Well, the inflationary multiverse
proposes that this crazy expansion didn't stop everywhere
at the same time.
Some areas kept inflating, even as others, like Ari,
settled down and cooled.
OK.
Picture it like bubbles forming in a giant expanding foam,
right?
Each bubble becomes its own universe.
So each bubble is like a separate universe,
disconnected from the others.
What's happening inside those bubbles?
That's where things get really mind-bending.
In the inflationary multiverse, not only
could matter be arranged differently,
but the fundamental laws of physics,
they could be different in each bubble.
Wait, hold on.
You're saying that in some of these bubbles,
gravity could work differently, or light
could travel at a different speed.
It might sound crazy, but that's
what this model implies.
Imagine a universe where gravity is way weaker,
where stars are enormous and spread out,
or a universe where electromagnetism is stronger,
so atoms bond in completely new ways,
creating matter we can't even imagine.
So it's like each bubble universe
is playing by a different set of rules,
like completely separate realities.
If the first level is about infinite copies,
the second level is about infinite variety, then.
You got it.
The inflationary multiverse is all about diversity,
not just what exists, but the laws that govern it all.
Wow, that's a lot to take in.
Yeah.
All right, two levels down, two to go.
I'm almost afraid to ask, but what's level three
got in store for us?
Level three, this is where we dive
deep into the quantum realm.
It's called the many-worlds interpretation,
and it's all about choices, possibilities,
and the crazy nature of quantum mechanics.
OK, I remember enough from physics class
to know that quantum mechanics is where
things get really weird, particles in multiple states
at once, cats both alive and dead.
It's mind-bending stuff.
Right.
Now imagine taking that weirdness
and applying it to the whole universe.
The many-worlds interpretation says
that every time a quantum measurement happens,
every time a particle picks one state over another,
reality splits.
OK, so instead of one reality, there
are countless parallel universes branching off
every single moment.
Precisely.
Imagine a tree with infinite branches.
Every decision, every tiny interaction at the quantum
level, it creates a new branch, a new universe
where that outcome plays out.
Hold on.
Are you saying that in some parallel universe,
I decided to wear a different shirt today,
or I ordered a different coffee this morning,
and there's a whole universe where that happened?
That's the essence of the many-worlds interpretation.
In this level of the multiverse, every possible outcome
of every quantum event actually exists
in its own separate reality.
That's a lot to process.
Yeah.
It's dizzying, but it comes from some pretty basic principles
of quantum mechanics, right?
Yeah.
OK, three levels of the multiverse down,
and my head is officially spinning.
Each one is more mind-blowing than the last.
Before we get to level four, which I can only imagine
is the most extreme of them all, I
think we need to take a quick break.
When we come back, we'll tackle the final level of Tegmark's
multiverse and discuss whether there's
any way to know if these mind-bending ideas are
actually true.
Stay with us.
Welcome back to Cosmos in a Pod.
We're on this wild ride through the multiverse, right?
We've explored three levels so far, infinite copies,
bubble universes with their own physics,
even realities built on pure math.
It's a lot, yeah.
And there's still one level to go,
and I have a feeling it's going to be the wildest one yet.
Oh, you're ready for level four.
Buckle up, because this is where we go full on
into the realm of pure possibility,
the ultimate mathematical multiverse.
OK, hit me with it.
What makes this level so ultimate?
Level four says that every universe that's
mathematically possible actually exists.
Think of it this way.
If you can describe a universe with equations, with math,
then it's out there somewhere in this massive multiverse.
Wait, hold on.
Any mathematical equation, any kind of logic,
no matter how strange, could be a real universe.
Exactly.
In this model, our universe with its specific laws of physics
is just one tiny point in an infinite landscape
of mathematical possibilities.
There could be universes where gravity pushes things apart
instead of pulling them together,
where time runs backward, or even
universes where reality itself is made of something totally
different from the particles we know.
So in a level four multiverse, we're
not just talking about different arrangements of stuff
or even different laws.
We're talking about completely different realities.
Operating on principles we can barely wrap our heads around.
It's like this cosmic library, right?
Each book is a different universe
with its own rules, its own possibilities.
And some of these books would be total gibberish to us,
stuff we couldn't even begin to understand.
Exactly, beyond our comprehension.
But in this level, they all exist.
So does that mean every crazy theory
physicists have ever come up with
has a universe where it's true?
That's a wild thought.
That's the implication, yeah.
A universe where string theory is the real deal
or where the speed of light is just a suggestion.
The possibilities are truly endless.
OK, we've got these four levels, each one more
mind-blowing than the last.
But let's be real here.
Is there any way to know if any of this is actually true?
It's a cool concept, but do we have any evidence?
Yeah, that's a big question.
It's the ultimate question.
And honestly, directly observing another universe
is beyond what we can do right now.
But that doesn't mean we're totally clueless.
There are a few really intriguing hints
that scientists are looking into.
OK, give me some hope here.
What kind of hints?
One way is to study the cosmic microwave's background
radiation.
It's like the afterglow of the Big Bang, right?
Imagine our universe bumped into another one way back when.
That collision might have left little marks on the CMB,
like ripples or temperature changes.
So we're looking for cosmic bruises from ancient universe
crashes.
Yeah, something like that.
It's a long shot, but it's something.
Another thing scientists are looking at is quantum computers.
These super powerful computers, they
can do calculations by exploring tons of possibilities
at the same time, almost like tapping
into parallel universes.
Like they're getting a glimpse into these branching timelines.
It's a thought and one that's got a lot of physicists excited.
And then there's string theory, which says our universe might
be like one membrane, one brain floating
in a higher dimensional space.
So like other universes, other brains right next to ours,
just vibrating differently in dimensions we can't see.
Exactly.
And those other brains, they could
be bumping into ours, creating subtle effects
that we might be able to pick up on.
OK, so maybe we can't hop in a spaceship
and visit a parallel universe right now.
But at least there are ways to test these ideas scientifically.
But beyond the science, I can't help
but think about what all this means.
If the multiverse is real, what does that say about us,
about our place in everything?
That's where things get really deep, really philosophical.
And that's exactly what we'll dive into right after this.
Welcome back to Cosmos in a Pod.
It's been a wild ride through the multiverse so far, right?
We've talked about these four levels, each one
crazier than the last, infinite copies of ourselves,
bubble universes with their own laws of physics,
even realities based on pure math.
It's mind blowing.
But now I want to talk about the really big questions, the ones
that keep me up at night.
If the multiverse is real, what does it actually mean for us?
What does it mean for humanity?
Yeah, this is where things get really interesting.
It makes us think about some of the deepest questions
there are, like the nature of reality, the meaning of life,
our place in this vast, maybe infinite cosmos.
OK, so let's start with reality.
If there are infinite universes out there,
does that mean our reality is somehow less real,
less important?
That's a tough one.
And a lot of people have struggled
with that question, both philosophers and scientists.
Some say that if there are infinite versions of us
out there living every possible life,
then maybe our own experiences don't matter as much.
I get that.
It's like, if everything that could happen
does happen somewhere, then what's the point?
Does anything we do really matter?
Yeah, that's one way to look at it.
But I think the multiverse can also
make our reality more amazing, more full of wonder.
Instead of making our reality less important,
it expands it.
Imagine a huge cosmic tapestry, right?
Woven with all these threads, and each thread is a universe.
Every thread is unique, beautiful,
and they all come together to make this grand design.
So instead of feeling small, we should feel a sense of awe,
knowing our universe is just one tiny part
of something much bigger.
Exactly.
It's like, when we realized that the Earth isn't
the center of the universe, our planet
didn't become less special.
We just got a bigger perspective.
I see what you mean.
So it's not about taking away meaning, but adding to it.
But what about the other big question, the meaning of life?
If there are infinite versions of us out there,
all making different choices, does that
mean our lives have no real purpose?
Purpose is a really deep question.
And I don't think the multiverse gives us an easy answer.
Some might argue that if every possibility is playing out
somewhere, then our choices, our actions,
don't have a lasting impact.
So it's like, there's a version of me
out there who's a famous astronaut, and another me
who's a struggling artist.
So my own path doesn't really matter.
I think the multiverse challenges
us to find our own meaning, our own purpose in this life,
in this reality, regardless of what our other selves might
be doing.
It's about focusing on the choices we make right now,
the relationships we build, the impact
we have in our own corner of the universe.
But it's less about finding a universal purpose
and more about creating our own meaning right here, right now.
Exactly.
It's about taking ownership of our lives,
recognizing the freedom and the responsibility
we have to shape our reality.
Wow, this has been an incredible conversation.
Exploring the multiverse has really stretched my imagination
and made me think about reality in a whole new way.
But before we wrap up, I have one last question.
If we could actually prove the multiverse exists, maybe
even travel to these other realities,
how do you think that would change humanity?
That's getting into some serious science fiction territory,
but it's a question worth asking.
Imagine meeting other versions of ourselves,
seeing universes where the laws of physics
are totally different.
It would completely change everything we know.
It would be like the ultimate culture shock, right?
Meeting aliens is one thing, but meeting other versions
of humanity, living in completely different realities,
that would really challenge our understanding of who we are
and what's possible.
It's almost impossible to grasp.
And it brings up some big ethical questions, too.
How would we interact with these other universes?
Would we try to help them, learn from them,
or would we be a danger to them?
Those are questions we might have to face someday.
But for now, they're just food for thought.
This has been an amazing deep dive into the multiverse.
We've explored the science, the philosophy,
the sheer mind-boggling possibilities.
And even though we've just scratched the surface,
I think it's safe to say that the universe,
or I guess I should say the multiverse,
is far stranger and more wonderful
than we could have ever imagined.
Absolutely.
If you enjoyed this exploration of the multiverse,
be sure to follow and subscribe to Cosmos in a Pod
and our YouTube channel.
We'll keep bringing you more amazing journeys
through the cosmos.
Until next time, keep looking up, keep asking questions,
and keep wondering about the infinite possibilities
that might be out there.