Cosmic Queries – Edge of the Universe

From the American Museum of Natural History in New York City, and beaming out across all of space and time, this is StarTalk, where science and pop culture collide.

This is StarTalk.

I’m your host, Neil deGrasse Tyson, your personal astrophysicist.

Today, we’re doing Cosmic Queries.

Topic, the edge of space time, the edge of the universe.

Chuck.

Hey, Neil.

You’re going to join me there.

I am.

But we can’t do it alone.

You know, whether you’re watching or listening, that I wear cosmically colorful clothing.

Yes.

But my shirt I’m wearing today is particularly cosmically colorful.

Yes.

It’s in your face.

It’s smack down.

It’s…

Well, you’re going to have to go to Patreon, or maybe we’ll take a picture of it, and you’ll have to see it on our website, or maybe you’ll see it on YouTube, but you’ve got to see this shirt.

Seriously.

It’s some pretty lovely celestial bodies going on there.

We have Janna Levin to help us.

Janna Levin, Professor of Physics, Barnard College, Columbia University.

Welcome back.

I love being here.

We needed you for this topic.

Because my knowledge of cosmology is little, and yours is big.

Not as big as the universe itself.

All right.

So, any time we do a Cosmic Queries, we bring her in.

I love it.

We bring in the big guns.

And Janna is the big guns, right?

Right, right.

Good stuff.

So, what do you have?

So, we got Cosmic Queries as we glean from all over the internet, and of course, we always start with a Patreon patron, because these people…

So, your book, Black Hole Blues, that’s still out there.

It’s still out there.

Okay, Chuck, we got to do it.

Black Hole Blues.

I’ve got to learn a harmony to that, so I can be like, over here.

There’s got to be a way when someone picks up the book, it says, Black Hole Blues.

Guaranteed more sound.

What if you just, every time you walk past it on the shelf.

Oh, you just heard it.

Yeah.

It’s an eighth.

We’ve got to put it on the shelf right here.

With a little riff behind it, you know?

Black Hole Blues.

So, that was about the discovery of gravitational waves moving through the universe.

Yeah, exactly.

So, right before that succeeded in the 50 years it took them to succeed.

Before we successfully measured it.

Ray Weiss, who’s one of the original architects, just was shaking his head and saying, you know, we don’t detect black holes.

This thing is a failure.

So, like, the title was just kind of like, it’s the Black Hole Blues.

But then he detected it.

The new title is called Novel Prize Winner.

The Nobel Prize Jig.

He’s sad all the way to the bank on that one.

Nice.

All right.

Yes.

Thank you for that.

Let’s start off, though, with a Patreon patron.

This is Chris Hampton, who supports us on Patreon, who wants to know this.

Could it be that the universe that we are in is actually finite, however the universal structure is infinite via size and relativity, meaning the universal structure gets infinitely smaller and vice versa, kind of like infinitely dividing in half.

I imagine it would look something like a very complex fractal.

He’s going a lot of places.

All right, Janna, take that however you want.

I’m going to write.

And I have a question for Chris first.

Is it Sativa or Endika?

Which is the one that he would have fallen asleep before making it to the end of the tweet?

I think that’s, I don’t know.

Well, we just all revealed our.

When I actually used that substance, it was called weed.

They didn’t put any other name on it.

It’s easy to pronounce and remember.

That was it.

If you went to your dealer and you went, so now it’s just the diva or indica, he’d be like, man, what’s wrong with you?

Smoke it.

Get the hell out of my house.

Go smoke that and get out.

Anyway, so you want to take a shot at this?

I’m into this.

I’m into this.

So my first book is about whether or not the universe is infinite or finite.

It’s a question we don’t know the answer to yet.

And the title of that book?

How the universe got its spots.

I remember that.

So how the universe got its spots is about could we tell the shape and size of the universe by looking in the hot and cold spots in the Big Bang and the light left over from the Big Bang.

But the question, let’s just take it really theoretically.

We absolutely do not know that the universe is infinite.

And it may well be that it’s finite the way the earth is finite.

That we leave New York City, we travel in a straight line.

Maybe we’d have to swim a little, get on a boat, but you travel in a straight line.

You’re going to come back to New York City again.

And so it could be that we…

But you can travel forever.

I was going to say, it’s infinite in what you can travel, in where you can travel.

It’s infinite in you don’t get to an edge.

Right.

You never get to an edge, which is beautiful.

So exactly the same thing with the universe.

You’re not going to sail off the edge of the earth, right?

You know, Spanish explorers wave goodbye and wonder, right, if they just go off the side.

But no, we know that’s not what happens.

And so similarly, we could leave the Milky Way galaxy.

We could watch it recede behind us.

We could travel in a straight line as possible and find ourselves coming back to the Milky Way again.

You know, and it’s so Planet of the Apes, right?

It’s like…

Damn you!

You finally did it!

Damn you!

What the hell!

Oh, that’d be great.

So my interpretation of that was that they went all the way around.

And so the interesting thing is that also means that if you look at distant galaxies, the light is also traveling all the way around the universe.

So it could be that some of those distant galaxies are the Milky Way and we’re seeing the light from the Milky Way wrap all the way around and come back to us.

We’d be seeing the Milky Way in the past.

So it would be hard to know.

Maybe we’d see an active black hole quasar with jets flying out in the early phases of the Milky Way and we’d think, oh, that’s just a different galaxy.

Wow.

Yeah.

So we’ve…

Because galaxies, young galaxies look very different from mature galaxies.

And we used to think that they were different kinds of objects in the outer universe, like quasars.

Why are they all distant?

How come there’s not a quasar right next door with these monstrous nuclear emissions?

And we had to figure out that it’s likely just younger galaxies.

And maybe we used to look like a quasar and we don’t anymore.

So even a distant galaxy looking back at us is seeing us in the past, given the light travel time.

So we could still look like a quasar to a distant galaxy.

Like we’re…

I have this huge, active galactic nucleus.

Because they’re not seeing us as we are now.

No, they’re not.

They’re seeing us as we were.

Billions of years ago.

Yeah.

Oh my God.

You know what?

I need some of that sativa right now.

Wow.

Well, and then it gets more because there are reasons that people start to suspect that there are extra spatial dimensions and that they are not only finite, but really technically really small.

Like that journey to go all the way around them is something that would happen incredibly quickly and it’s too small for us to like literally stick our hands in that direction in some sense.

So we’re looking everywhere.

There’s extra dimensions are everywhere, but we can’t actually notice them.

What does it mean for a dimension to be smaller than another dimension?

Yeah.

So think of like a straw is a good example where it’s a two dimensional surface.

You know what the first straws were made of?

I’m going to go with flax.

No.

Thank you.

Thank you for getting that.

I knew it.

Oh, God.

The only reason I would, it’s because flax and hair.

Oh yeah?

Yeah, that’s the only reason I would have the connection between flax and straw.

So a straw is small in one direction on the surface, right?

If you think there’s a direction in which it’s totally wrapped up and small.

And then there’s a long direction.

So straws are mostly long.

They’re mostly long.

And you could glue the top end to the bottom of a straw to make that long direction also finite.

So then you just travel around.

It could be really big.

It could be, you know, a mile around, but still be connected.

But it’s only a few millimeters around in this direction.

In this other dimension.

So literally the length of traveling before you come back to where you started is smaller.

So most of how you use a straw does not access that other dimension.

It’s only the length, because you’re trying to get the liquid from here to here.

Yeah.

And so you’re using the long dimension of the straw.

So then the question we start to ask is what if the universe is a kind of space-time origami when it’s created in the Big Bang, that all the dimensions are wrapped up, maybe in very complicated ways, like the dimension of the straw being wrapped up, but one dimension just gets very, very big, or in our case, three.

We have three big dimensions.

We have time, which is a fourth.

So, we know there’s up, down, north, south, east, west.

That’s it.

You specify those things, and you definitely know where you are in space.

You specify time, and we can actually meet.

Right.

Here we are.

But those extra directions just maybe didn’t ever expand.

And so, one of the things even that I’ll work on, and string theorists will work on, is why would only three dimensions get large if those other dimensions exist?

Interesting.

So, it could be that we’ll understand the large connectedness, finite nature of space by looking in like really high energy accelerator experiments.

Because people have asked at the Large Hadron Collider, could you perceive these extra dimensions if they exist?

Wow.

That, I got to tell you.

Chris?

Are we done with the show?

And people will be back next week.

It’s an entire show worth of…

Next week, we’re just going to let you think about that.

It will be…

It’s a week’s worth of mind-blowing…

That is…

That is a big start to Cosmic Queries.

Wow, man.

That’s fascinating stuff.

Just fascinating.

Let’s move on to Paul Love, who says, given that…

Is that because you can pronounce his name?

That’s why we’re going to him next?

Let me tell you something.

As a matter of fact, I think I’m just going to call everybody Paul Love.

Paul says this.

Given that our universe expanded from a single point and is expanding in all directions, how does that not define the shape of the universe as spherical?

How could something flat or saddle shape come out of that?

Well, it is true if there is an explosion in space, it tends to have a kind of spherical cloud left over as debris, so when a star explodes, we will see often nebulae and they are often spherical-ish.

Very beautiful too, beautiful nebulae.

Very beautiful.

Sometimes they plow into stuff and change the shape, but basically, yeah, then you can point inside this debris, you point to where the center of the explosion was.

So that’s not how it works for the Big Bang.

So for the Big Bang, you cannot imagine that the space exists first and that you are exploding into the space.

It is actually a creation of the space itself.

So everywhere in the universe was once at the center of the explosion.

There is no plowing out.

It’s as though, and you can think of it any shape you want.

Make some crazy, you know, people like the balloon analogy, so now make some crazy balloon twisted up crazy thing.

And a poodle, a balloon poodle universe and the whole thing stretches and the whole thing whole thing was once a point.

So every single point on that surface and people get tripped up.

It’s part of that fabric, if you want to call it.

So the center is everywhere.

The center is everywhere.

We are at the center of the Big Bang.

As is every other point in space, isn’t the center of the Big Bang.

But can I say, can I say that, will you allow me to say it differently?

Can I say, there is a center, the only way you can access it is to go back in time to the beginning of time?

Well, you could say…

Oh, man, talk about dementia.

So, you can access the center of all of this only at one point in this coordinate system and it’s at t equals zero, right?

I would say…

And it’s there.

If timeline is just always there, there’s the center.

Yeah, if we’re going to be really, you know, split space up in very fine-grained terms, this point was at the center back at t equals zero and this point was at the center back at t equals zero.

They just were all closer together.

Right.

So, the whole…

So, it’s just the collapse of those points at t equals zero.

Gotcha.

But I like what you said, though, which I think is what people have to really think.

The space itself was created at the second…

Not second, the millisecond, microsecond, whatever, nanosecond…

A bajillionth of a second.

That’s an official fraction.

The bajillionth of a second afterwards.

That space was created then along with everything else.

I think that’s like 10 to the minus 43 seconds, which would be a trillion, trillion, trillion, trillion-ish.

So, you know, right then.

So, I mean, if you think of it that way, because what you’re thinking about is these distances between the stuff that we see and we think they’re empty, but they came from that thing.

Yeah, from the Big Bang.

From the Big Bang.

Yeah.

So, another reason why people get tricked out.

Chuck just blew a gas can.

I know, man.

So crazy.

We just lost Chuck.

I love it.

I would love if there was an actual steam effect.

Out of the ears?

So here’s where people get tripped up with the balloon analogy because it’s flawed, as are all analogies, is that a lot of people immediately want to point to the center of the balloon, the empty space inside.

But you got to give up on that.

All that exists is the skin of the balloon.

That is all that exists.

I’m okay with the center of the balloon because that’s where the balloon was at T equals zero.

Right.

So you could think of it, good, I could only consider the center of the balloon as snapshots, like movie frames.

So it once was there, and then it was a movie frame over here, and then it was a movie frame.

But the center of that same balloon is still now at the outer reaches of the balloon because it came from the center of the balloon.

So imagine you painted dots all over the little infinitesimally small balloon.

They were glued to, you know, their stains on the skin of the balloon.

The dots themselves don’t move.

And then you push all that down, so all the dots are together, and then you pull them apart.

In some sense, those are the galaxies that came later.

See, the galaxies aren’t moving.

The stain on the balloon doesn’t move.

It’s the skin, the stretching between the spots.

So, in fact, nothing piles up the way it does when a supernova explodes.

Everything actually just gets more and more diffuse as the universe expands.

Holy crap.

Next question.

Wild, man.

Thanks, Paul.

Here we go.

Let’s go to Brendan Rico Suave.

You just screw with me, Brendan.

Okay.

Brendan wants to know this.

I’ve recently heard of a new study that states the universe is thought to be in the shape of a loop, whereas previously it was thought to be flat.

But in the explanation given, the nature of the loop shape states that it travels far enough in one direction that you’ll end up back where you started, which is what we talked about earlier.

My question is, wouldn’t this happen regardless of actual shapes of the universe?

So his point is like, no matter what your shape is, would that happen?

Yeah.

And I think that you can say…

I think that we have to take a break.

Oh!

Wow.

I should have seen that at the corner of my eye.

When we come back, Janna Levin is going to tell us, do we live in a loop universe, or not, on StarTalk?

We’re back, Cosmic Queries, StarTalk.

Chuck Nice, my co-host.

Thank you.

All right, Janna Levin, friend, colleague up at Barnard in Columbia, doing that physics thing, cosmology.

Someone’s gotta do it.

Somebody’s gotta blow people’s cosmological minds.

And so, tell us, as the question Ed asked, would the universe loop back on itself no matter its shape?

So, not necessarily.

How do you know what shape the universe is in the first place?

Yeah, it’s really, we don’t ultimately know the shape.

We know that we can see the distance light has been able to travel since the Big Bang because we can’t see anything faster than the limit of the speed of light travel time.

And we know that the universe is expanding.

So that’s actually 92 billion light years across about, that we can, that’s what we call the observable universe.

Now, it’s possible that it’s not 92 billion light years across that even within that range that the universe has folded back onto itself in some way.

And we’re actually seeing repeats of things.

We’re starting to see, it’s kind of like a hall of mirrors thing.

We’re starting to see the light multiple times.

How would you know?

Yeah, I was going to say, how do you figure that out?

It is very, very hard to figure out.

So there have been extremely clever ideas and most of them rely…

If I get my telescope and look out and I see Chuck waving at me.

Right, exactly.

Right, when he was a little baby.

You hear the one about the…

So it’s true, we’re looking at ourselves in the past, which is very hard to distinguish if, for instance, if we’re looking at galaxies, that’s very hard to do.

But there are patterns in the hot and cold spots left over from the Big Bang if it fits into a specific shape.

So imagine something just totally platonically beautiful and crazy that the universe is like a dodecahedron, all of whose faces are glued together.

So it’s like crazy origami.

That thing is, I mean, there has so many loops and…

Dodeca-20-sided.

Yeah, that is…

With triangles, 20 sides.

Right, and that is conceivable, kind of what we call topology or connectedness of the space.

It would actually start to imprint the patterns of the dodecahedron in the light left over from the Big Bang.

So if you imagine there’s tiny little hot and cold spots that you would start to see in the distribution of the hot and cold spots.

That shape.

That shape would be reflected in a very subtle way.

Really?

Yeah.

Wow.

So the reason the-

You don’t mean reflected literally.

You mean manifested.

Manifested.

So how the leopard got its spots is actually a very similar mathematical problem because you’re asking about enzymes being high or low in the developing embryo and it turns out that the shape and the size of the animal, whether it’s tubular or when those spots are hitting it, that it will determine what kind of spots the animal gets.

So in an actual leopard, zebra, stripes, these things are things you can predict by solving for the mathematics of things that are above a certain threshold or below a certain threshold that that pattern of stripes or spots will reflect the geometry of the animal.

And the black panther is a leopard, you knew that.

Yes, I did know that.

And the black panther has spots.

Now that, I didn’t know.

On its skin?

It has spots.

On its skin.

If you look very carefully, you can see the spots.

Oh wow, amazing.

Well, so how the universe got its spots is a similar mathematical problem.

We’re solving for hot and cold spots in a particular geometry when the universe was like a developing embryo, basically.

And this goes back to Alan Turing.

Who solved some of these problems for the animal.

But like a black panther, does the universe care about injustices to the black man?

I mean, if this is any evidence, if this planet is any evidence.

Just to bring that into modern reference.

Or does the universe have vibranium?

There you go.

There you go, I’m the same.

Well, you know, we can hope that we’re the bad example.

And then elsewhere in the universe there are better examples.

Nice, well said, well said.

All right, Chuck, what else you got?

All right, here we go.

This is Tim Braid, who wants to know this.

A very recent study in the Astrophysical Journal found that galaxies may be rotating in sync with other galaxies millions of light years away.

Galaxies separated by six megaparsecs were found directly interacting with each other.

What is your opinion on this?

First of all, is that empirical, the fact that these galaxies were actually interacting with one another?

I think that that study is probably still controversial and probably still requires other.

Which means probably wrong.

I’ll be your translator.

I know, I can’t say.

That’s an interesting study.

Probably wrong.

It’s controversial, probably wrong.

I mean, these things can happen, but it just sounds not that likely.

And so there will be a lot of people doing observations with different wave bands with different perspectives to try to break any possibility that it’s a quark of this particular observation.

But six megaparsecs, that’s pretty far away.

And so you would think that you would be dominated there by the expansion of the universe and not interactions.

We definitely interact with other galaxies.

That’s not a big surprise.

So Andromeda, we’re gonna collide with Andromeda.

That’s a happy future.

Like imagine when Andromeda gets much closer, how cool the night sky is gonna be.

It’s gonna be like right there, you’re gonna see a whole galaxy.

It won’t be as cool as you think.

I’ll tell you at the end of your answer though.

It’s not gonna be as cool as you think.

Cause is it coming in edge on?

It’s a disturbing reason why it’s not gonna be cool.

Well, speaking of edge on, now you just, I’m sorry, cause I’m a little all over the place, but I gotta get this in before we move on.

So speaking of edge on, so if you’re looking at something edge on, how do we flip it to get the imagery to know that we were looking at the disc from the edge?

So we do that with our own Milky Way.

We’re in the Milky Way, so we’re seeing the rest of the galaxy edge on.

We’ve never seen the Milky Way as human beings from above, but we have these beautiful constructions because we just map things as accurately as we understand where they are also in space.

So we just build an atlas of it, basically.

You build a numerical model based on all of your observations of the Milky Way, the gas, the dust, the stars, everything where the spirals are, where the gaps are, and then you just allow yourself to move in that digital world and look down from above, but it’s a numerical experiment.

So it’s the modern version of map making because I make a map in three dimensions.

Exactly, and once you have a map, you can go anywhere you want, but a three-dimensional map, you can go anywhere, and plus, we see all the gas and we’re kind of flattened in the sky, and there are other galaxies out there that are flattened, and we can see them at all, not one galaxy at different angles, but a million galaxies all scattered in random angles, and so it’s pretty easy to figure out what we look like by looking at others.

By looking at Earth and adding and adding.

And that’s what we look like until we collide with Anjana, but one of the things I took solace in, but I feel like Neil’s about to make me very uncomfortable.

But the whole solar system’s supposed to stay together, right, and get knocked around.

We should stay together.

So we might end up in Andromeda before we fully collide.

Like they could pass each other, they could collide, move through each other, and we could end up in Andromeda looking at the Milky Way.

And the Milky Way, we’re going to leave a forward in address.

So what’ll happen is there’ll be a lot of sort of dissipated energy, and the system, well, they’ll pass through each other, and back and forth.

We’ve done this on a computer.

And it’s like a rubber band kind of thing, and it kind of dies down, and it settles into one double large massive system.

Okay, so what’s the bad news?

Okay, so I hate to break the news to you.

That sounds like good news to me.

So if Andromeda were a hundred times closer, it wouldn’t be any brighter on the sky.

Hmm, interesting.

Okay, I believe you’ve lost me.

You totally lost me there.

Yeah, tell me why, it’s not obvious.

Okay, I’m gonna tell you.

Yeah.

All right, so Andromeda has a certain size on the sky.

Correct?

Okay, it has a certain extent.

Mm-hmm.

And on a very dark night, not in the city, but where the moon is not out, you can see this fuzzy thing in the sky.

So that’s in the Andromeda galaxy.

It’s two million light years away.

Mm-hmm.

All right, there’s a certain amount of light coming from Andromeda in that patch on the sky.

Right.

So we reference it’s something called a surface brightness.

It is how bright is Andromeda over that patch of sky, over that surface patch on the sky, surface brightness, okay?

If we bring it half as far away, okay?

Make it only half as far.

It is how many times brighter?

It should go like the square.

Like the square.

But then the area’s also going to be four times brighter.

But the area’s gonna go like the square.

By a factor of four.

So.

So the whole system is getting brighter, but the surface area is remaining the same.

So it is not gonna be more apparent to you in the night sky than our own Milky Way is on our own night sky.

I’m very sad to report that.

But it’ll look cool.

It’ll look cool.

No, it’ll just still be fuzzy, can I see it?

I gotta get out of the city, get rid of the full moon.

Now I see the colliding galaxy.

No, sorry, I’m very sorry about this.

Janna, I’m sorry to report this.

It’ll just look like our own Milky Way galaxy.

If the drama were right here next to us, it would just look like our Milky Way in the night sky, which you cannot see from New York City.

But you can see it with one of those apps, like you can just, you know, you can hold it, it could be like, Hold up your smartphone.

And it could be like down there, and it’ll show you like a beautiful.

It’ll show you Andromeda on its way.

And you pump up the count, the intensity.

Who needs eyes?

I love it.

I’m overrated.

We are practically blind.

This is the moon model for astronomy.

Yeah.

Who needs eyes?

We’re becoming cyborgish, you know?

She is so right on this.

Chuck, Chuck.

As the centuries went on, we discovered how blind we actually were.

Yeah, that’s amazing.

All right, there we go.

Okay, let’s move on to David.

By the way, those Hubble photos?

Yes.

If you go to those objects, you don’t see what the Hubble saw, because the Hubble sees better than you do.

A lot better.

A lot better.

I mean, if you could just like stare at it for 10 days.

Or if your eyeballs were like gargantuan, then it’ll look like what the Hubble sees.

All right.

Cool.

This is David Eduardo Perales Martinez, who wants to know.

Oh, you did good there.

Well, not bad.

You know, my wife.

Let me hear.

My wife is Puerto Rican.

So she’s a little bit of a…

Let me hear that again.

Go.

David, or would be David Eduardo Perales Martinez.

Martinez.

Yes.

Who says this, why is it so hard to prove the existence of other dimensions?

Thank you.

David from Mexico, or Mexico.

I want to ask that a slightly different way.

Go ahead.

If there was another dimension as big as the three that we’re in, would it completely manifest to us?

Probably.

There’s a hitch.

So you would think, yes, as long as that dimension was very large, then we would be talking about a world in which this did not confine us, right?

So let’s say I have skin, which seems to separate my inside and my outside.

But if there was another…

If there was another dimension, you could do one of those spooky surgeries without puncturing any skin.

You could just go in there and touch people’s organs.

This would not be a separation of inside and outside.

Well, there’s also an analogy to that, is if you only live in two dimensions, then you only have height and width, you have height and width but not depth.

So if you don’t have depth, if I look at you in two dimensions, I can see all your organs.

For you, skin would be a line.

I just reach in and pull out your spleen or whatever.

You can’t see because you’re in the, and all you see is the outer skin, which is just a line.

Which is just a line.

Yeah, and now our outer skin is a surface.

Right, so which is why you can’t actually probably have a very effective organism in just two dimensions because let’s say they had a mouth and a tube going all the way through them, it would actually cut the two sides in half.

So you can’t have what we consider to be normal metabolic functions of, okay, anyway.

You don’t have porosity in two dimensions.

Oh, so if you drop water on soil and then it just soaks in, or you drop it on a sponge and it soaks in, in two dimensions, there’s no such thing as…

No soaking.

There’s no soaking in.

So you just have a bulb of water.

Bulb of water, correct.

Sitting on top of it.

Because porosity enables, you have two, let’s say two rocks are touching here, but then the water can just go around another side of the rock, but in two dimensions where they touch, there is no way past it.

It will just stay above it.

Is that where you’re able to smell what the rock is cooking?

No, I’m so sorry.

So here I will tell you this.

Some people argue that the reason why the universe is three dimensional is because the universe tries to be many different ways.

There may have been an infinite number of big bangs in the past and the future.

You can’t really talk about it in temporal relativeness, but if the universe created a two dimensionally large universe with all the rest rolled up and small, you couldn’t have organisms in that universe to ask the questions.

So you’d need at least three.

And then let’s say you had four spatial dimensions, then you have the problem of things drift away from each other in such a way that it’s hard to have organized systems.

So just like Neil was describing a two-dimensional creature isn’t aware of the third dimension, but if they became aware, they could just kind of float away from their city, right?

It becomes, you have more volume of space to fill.

The cross section for interaction goes down.

So now if you add another dimension, the cross section for interaction goes down again.

No, but we successfully exist in three dimensions in spite of the challenges the two-dimensional creature would face upon accessing a third dimension.

So why don’t four-dimensional creatures pity us?

Yeah, right.

Well, that is a good question.

Could the complexity, I’m not saying they’re true arguments, but some people argue that you couldn’t in the four dimensions get the successful complexity.

And some of those arguments are, they get complicated based on string theory cross sections and annihilations into photons and what’s left over after all of these things in the Big Bang.

It turns out that only a tiny, tiny bit of stable matter is left over already in three dimensions from the Big Bang.

Wow, so it could be.

Wait a minute.

Let me kind of agree with what you just said, even though I just disagreed.

What you’re saying is, in three dimensions, it could be optimal for particles to get together and make molecules and molecules to make macroscopic objects.

If you add a fourth dimension, you’re adding a degree of freedom of where things can hang out and possibly never then find each other ever again.

If you think about the volume of the universe as going up radically with the volume of dimensions, then you’re diluting everything in the universe significantly.

The concentration of what could be, ooh, interesting.

So the fact that you’re even asking that question means you are a being in an optimized universe to even pose the question in the first place.

So the two dimensional people couldn’t ask this question?

Right, because they couldn’t be two dimensional.

They could be three dimensional people because the structures are too simple to allow.

And four dimensional people, there’s too much play space.

So let’s take it, your first question was, would we know it if the other dimensions were large?

Here’s the hitch, you would think we would, but here’s the hitch, even if all of those problems were solvable, there is an argument that we could be glued to a kind of a membrane, which is a three dimensional surface floating in this higher dimensional space.

And we’re like glued to it.

It’s the.

Elmers.

The Elmers, the way the fundamental forces work between.

They keep us there.

They keep us on the membrane, and the only thing that happily goes off the membrane is gravity itself.

So that all other forces are glued to this membrane, that’s where they live.

So that you would think like a particle to you interacting with that membrane could be a string in the higher dimensional space.

Passing through your space, manifesting as a particle.

Manifesting as a particle.

So like imagine cutting a string, it would look to you like a dot.

Right.

An infinitely thin string.

And that is wild.

So you think it’s particle physics.

Do I think about it in two dimensions?

I think of passing a hollow sphere through two dimensions.

What would that look like to the two dimensional people?

They’d see a dot and say, well, that’s cool.

Oh, then it becomes like a circle.

And it gets bigger and bigger and bigger.

Then it maximizes out at the diameter, but they don’t know this.

And then it gets smaller then, it gets a point and disappears.

And they have no idea that it’s in a sphere.

And all kinds of mystical, magical hypotheses come out.

And the scientists analyze it.

We just say stuff pops in and out of existence.

We don’t know why.

So one of the, yeah, absolutely.

So one of the things that we’ve worked on with extra dimensions that make them not just an oddity, but maybe something we’ve already observed.

One of the things we’ve worked on on our extra dimensions.

This is, Janna, what’s in your basement?

She’s a superhero nemesis character in the making.

My superhero character name is Jan 11.

Isn’t it good and it’s a prime number?

I mean, I’ve got to work that somehow.

No, no, no, you don’t want to be the superhero.

You want to be the nemesis.

That’s way more fun.

It is way more fun.

That’s Jan 12.

My evil twin, Jan 12.

So the interesting thing there that people have thought about is that maybe something like dark energy is actually a quantum phenomena trapped in the extra dimensions that we can’t perceive the extra dimensions directly, but we’re indirectly perceiving them through the dark energy.

Or dark matter is regular matter in the higher dimensions leaking over.

Right, through this membrane.

And we’re just doing this and it’s just mysteriously there.

Yeah, people have definitely wondered if dark matter could have to do with extra dimensions.

So gravity is the thing that is the medium?

Is that the deal?

Gravity is space time, so gravity can’t be confined.

Gotcha.

To, otherwise that would be no meaning to the extra dimension.

Stupid.

You think?

Chuck, we gotta take a quick break.

When we come back, more with Janna Levin on the edge of the universe and beyond when StarTalk returns.

Hey, we’d like to give a Patreon shout-out to the following Patreon patrons, Roy Hill-Percival, Jose Clark, and Dr.

Janet L.

Walsh.

Thanks so much, guys, for helping us make this little trip through the cosmos.

And if you would like to support us on Patreon, go to patreon.com.

We’re back, StarTalk and Cosmic Queries, the edge of the universe.

There’s only one person in arm’s reach out there that who could do this, Janna Levin.

Janna, she’s our go-to person for extra dimensions.

I love being the go-to person, it’s the best.

Totally the best.

I have actually written papers on extra dimensions.

It is a genuine direction in my research is to think about this.

So when she disappears, we’ll know.

Wouldn’t that just be so cool?

I just got up and then went into the fourth dimension.

And then might just disappear.

This is how Monsters Inc.

Yeah.

These are doors that came out of the factory.

This was an uncelebrated fact of that movie.

These are four-dimensional portals.

They’re basically wormholes.

They’re amazing.

Each door, this is the door to the kid’s room.

And the monster takes it home at the end of the day and they open the door and the other side of the door is the kid’s closet.

And then they come out in the closet, scare the kid, go back through the door and they’re back at home.

It is a great movie.

All right, let’s go to, you know what?

Let’s go back to a Patreon patron.

This is Solarcero de Rai, okay, who says, what do y’all think about the, you like that?

What do y’all think about the idea that matter consumed by black holes has been recycled and manifested back into the universe as dark energy?

So matter coming out the other side maybe.

Right.

So is there any correlation between the matter consumed by black holes and dark energy?

Could black holes and dark energy, dark matter, be different sides of the same coin?

Well, I mean, where to begin with this?

That’s right, this is a lot.

I can lead off by saying there’s an urge to take everything you don’t know and assume it’s related.

So I’ve got people talking about dark matter, consciousness, God, and dark energy all as one thing.

Right.

And quantum spookiness.

Yeah, someone asked me when they take ayahuasca, is it possible that they have gone to a higher dimensional space?

Okay.

My answer to, in an attempt to not be totally dismissive, was to say, well, if it’s a platonic form that we can learn about by exploring the mind, then in that sense maybe, right?

Like a perfect circle doesn’t exist in reality, nor will a perfect circle ever exist anywhere in the universe, but you can touch it in your mind, right?

And it’s an experiment we can all perform, so that in that sense, we go places.

Unlocking secrets of the mind, if not secrets of the physical universe itself.

Yes, yes.

In other words, you high.

So what do you say about dark matter, dark energy?

So, okay, so let’s just start with the falling in and coming out, and so there were very early on people who thought a black hole could be bigger on the inside than the outside, it could be as big as an entire universe on the inside, it could actually lead to a white hole, which is basically a big bang.

So you fall into the black hole, and that is completely confined by the event horizon, nothing ever comes out, but inside it is like something as big as an entire universe.

Another universe.

And that universe will remain.

Like a TARDIS.

Bigger on the inside than on the outside.

Oh, and right.

Exactly.

It’s just like Dr.

Who’s TARDIS, and so we would never know about that universe.

It would not communicate with us.

Check, Chuck’s street cred.

TARDIS is an acronym for what?

Oh, no.

Oh, no.

I can’t remember it all.

Phone booth in London.

I don’t know what time.

Time and relative dimension in space.

Time and relative dimension in space.

TARDIS, there you go.

Usually the and doesn’t make it into the acronym, I’m just going to say, you know.

Okay, so that was an interesting idea and a lot of people object to it because it in some subtle way suggests an unstableness to big bangs that might make it so that this world couldn’t be stable if that were true.

But honestly, it’s not completely off the table.

There’s a lot you could talk to some very important early relativists and they will still say that’s what happens.

Relativists, an expert on relativity.

On relativity.

So then there’s a separate, totally separate question about dark matter.

There is a suggestion that the black holes themselves could be dark matter.

Meaning that they are invisible, like dark matter is, technically.

And they could populate the universe almost arguably large enough to explain this missing mass, this missing matter.

It’s on the edge.

It’s definitely under pressure.

Right, but there’s a problem with big bang nucleosynthesis, if it’s ordinary matter.

The black holes don’t have to be made by collapsing stars out of ordinary matter.

But you’re absolutely right, we don’t know how to make enough ordinary matter.

Right, so they’re not made from stars.

So can I show you my black hole lunchbox?

Let’s do it.

I want to know what’s inside the lunchbox, but I can never find out, can I?

If my hand goes in, will it never come out?

Yeah, exactly.

And inside of it is a black hole thermos, but of course.

It is confusing.

If you fall into a black hole like this, I guess you can’t see your hands.

Yeah, you’ll disappear in front of yourself.

Yeah.

So you have a black hole thermos, and it is filled with liquor.

This is an inversion of the known universe, because in this particular case, inside your black hole.

I have the Milky Way inside the black hole.

You did not just pull a Milky Way out of a black hole.

Because the black hole’s always inside the Milky Way.

I am just gonna say that that was the most committed joke I have ever seen in my life.

For those of you who don’t have a camera, I’m just telling you, Neil had an actual Milky Way candy bar inside of a black hole thermos.

Inside of a black hole lunchbox.

You’re just jealous.

I’m a little jealous of the black hole lunchbox.

So, the last question, which is pretty hard, is could they all be connected, the stuff that falls in and comes out?

And classically, we would say no way.

Ventriloquism separates everything from the inside to the outside, but then there’s like quantum entanglement, across the ventriloquism.

Maybe some particles on the inside are also the same thing as the particles on the outside.

They’re the same particles because of entanglement and wormholes and some crazy stuff that nobody really, it’s all just very conjectural now, but maybe we’ll come back in 20 years and we’ll be like, figure that out.

And we’ll have something for it.

We’ll have a follow up to this Cosmic Queries 20 years from now.

Yes, exactly.

We’ll roll us in wheelchairs, not you, but me and Chuck.

Because I’ll be doing my regenerative medicine.

So we gotta go lightning round here.

Chuck, let’s do it.

Here we go.

So Janna, you’re gonna answer each soundbites.

Okay, amped.

This is Bunders85 on Instagram and wants to know this.

I know it’s off topic, but one of your last shows, you were talking about the information on the surface of a black hole.

What do you mean by information?

Do you mean temperature or speed or what is information?

Ultimately, we are completely definable in terms of our quantum numbers.

It’s just a list of facts about us, information about us, and relative locations and organizations.

My quantum number is 42.

So, of course Neil’s is.

So, it’s something as simple as your mass electric charge.

The number of atoms in my body.

Well, let’s take a single fundamental particle in your body.

It has mass charge spin and it’s identical to every, let’s call it an electron in this case, every other electron, identical.

One’s not a little bit heavier, one’s not a little bit lighter.

We’re completely definable in terms of that information.

And you cannot destroy that information.

Interesting.

And so, in quantum mechanics, you start to stop thinking.

Wait, wait, if I melt Chuck and he’s a puddle.

Yeah, technically, all of that information is still in the universe.

Right, it’s just arranged differently.

It’s just arranged differently.

It’s arranged, oh my God.

In principle.

Wait, wait, wait, no, no, how about the information?

That’s an awful thought.

If Chuck is a puddle on the ground, that’s a different Chuck from the Chuck I’m talking to right now.

How’s that information still there?

Yeah, so the info.

I will never change.

Well, technically, having information preserved doesn’t mean there can’t be local change, right?

So I can definitely change things locally, but I still have to have the same information content.

In the total system.

In the total system.

So I have to be able to reconstruct something.

It doesn’t mean that there’s no change.

With what’s in the system.

With what’s in the system.

Got it.

But you don’t have to necessarily be able to reconstruct the exact same thing.

You just have to be able to utilize the same information.

Right, in principle, I should be able to, so if I took a page of the encyclopedia and burnt it, I should be able to reconstruct it.

In principle.

Of course, nobody can ever really do that.

It would take longer than the edge of the universe and we don’t have that kind of computing power.

So there’s physical impossibilities, but.

Ignoring those complications.

Ignoring those complications.

But it’s supposed to.

For the black hole, the argument is that what’s actually might be happening is that the information as it’s falling in, which is basically all, you know, everything.

Everything.

Right.

Never actually makes it inside the black hole.

It becomes encoded on the boundary, which is the event horizon.

So it’s actually a hologram.

So I’ve got lightning, let’s lightning it.

All right, that was not lightning enough.

That wasn’t lightning enough.

This is Elias82 from Instagram says, NASA reported that Voyager 2 discovered two new details about interstellar space.

How does that change our understanding of dark energy beyond our solar system?

Or does it?

It probably doesn’t because it isn’t a detector of dark energy or dark matter.

We have no detectors of dark energy or dark matter yet.

None successful.

And so what, but it is amazing that it’s the first human-made object that’s gone interstellar.

And that really is quite spectacular.

It’s just broken out of basically the sun’s magnetic influence, so it’s able to get cosmic rays and things that are protected in the solar system by the sun’s magnetic field.

We used to think the solar system was how far out of the planets.

And then you have like the Kuiper bell of commerce, then you have the Borg cloud.

Then you say, well, really, at what distance does an object no longer know that the sun is in this direction?

Because the sun has magnetic influences that go very far, and you reach the point where all the field measurements are sort of in this soup that permeates the entire galaxy.

And so it’s a transition from the sun is this way to I got stars in every direction.

And so-

It’s still moving so slowly that it will take what, 10,000 years to reach another.

Oh, no, no, no, 70,000 years.

70,000 years.

All right, this is from Robert Weber, who says, thanks so much for educating and inspiring us.

What news in science do you find most interesting and important right now with respect to your field?

Wow, that’s a great question.

Well, we do live-

In a sound bite.

Yeah, we are in a very lucky time because we have discovered bare black holes in this miraculous way.

So I do think that the most exciting things have to do-

One of them has, yeah, is eating Neil’s Milky Way.

I do think it is where the small meets the large and it will be that way for a long time, meaning what the Big Bang tells us about dark matter and dark energy and the universe on the larger scale and why those things are folded together, thinking about the universe on the bigger scale and on the small scale.

So where quantum physics meets general relativity-

For sure.

Is an unresolved territory.

That’s right, and so that’s why we use all these really extreme settings.

It’s the bad land.

Right, if you wanna understand where quantum mechanics meets gravity, you gotta do it in the Big Bang or on black holes.

All right.

This is Pablo Gristensko.

I don’t know, Pablo, I’m sorry.

Can you please help me put inside my head one more dimension?

Three is fine, but how can I grasp more?

That’s a-

What do you do with people?

What do you do with people to let them understand?

I think it is absolutely imperative that everyone understands that nobody can just blanketly visualize higher dimensions.

We’re accustomed to looking at dimensions from the outside looking down.

We can’t do that.

So what we can do with the kinds of things that Neil was describing earlier, which is imagine three dimensional cross sections of things.

So visualizing a hypersphere, which is a higher dimensional sphere as an intersection of it with our three dimensions.

And it would be a series of spheres.

That would max out and then spheres would go back.

But the one last thing is to do the difficult example of being a flatlander and you will actually, just by going down a dimension, start to get it.

And I can add that if, I’ve said this in a couple of StarTalks before, but here’s another moment to do so.

If a line is bounded by points and a square is bounded by lines and a cube is bounded by squares, then a hypercube is bounded by three-dimensional cubes.

The sides of a hypercube are three-dimensional cubes.

Right, and you just, mathematically, you just work your way up.

You just keep going up, and the math will take you there.

There, that’s, there you go, math.

It sets you free.

There you go.

This is a real example where the math makes it a lot easier than trying to visualize it.

Okay, there you go.

Said no one ever.

Let’s convert this to math to make it easier.

That’s your higher dimensional differential geometry.

Okay, this is Eric Spenson, Mark Eric Spenson.

He says this, Neil, you have said before the dark matter should really be called dark gravity, and it really stuck with me and helped me understand it better.

Do you have a similar and alternate name for dark energy that better summarizes the phenomenon?

I’ll give it a shock, but I want to hear…

Let’s see what Janna says.

Janna.

I would just call it dark expansion stuff.

We don’t know what it is.

Dark stretching?

Stretchy stuff.

But definitely dark gravity is what dark matter is.

It is literally dark gravity, and I’m totally cool with that.

Are you totally cool with that?

Totally cool with that.

Is a neutrino dark gravity?

Uh-oh.

Sure.

That’s a form of dark matter.

We have examples of forms of dark matter that we have detected.

They’re just not plentiful enough to explain so much of it.

Yeah.

But there are things called neutrinos, which we do detect, and they are dark, meaning they don’t interact with light.

I wouldn’t call neutrinos dark gravity.

I’m pushing back a little on this.

That was rough, man.

Uh-oh.

You got front row seat.

Yeah.

I’m nerd fight.

Right now, I got my popcorn.

I’m just like, nerd fight.

Oh, this is good.

I will jump in with the dark energy, though, what if we thought of it as like an invisible ocean?

Because that’s sort of what the dark energy is around us all the time, and it’s as though we’re in a storm of dark particles and dark energy.

It’s just that it’s really that it’s invisible is the thing.

You can see right through it.

It’s not that if you had it in your hands, it would look dark.

It’s invisible.

Right, right.

So, yeah, both dark and energy really don’t apply.

We need a better name for it.

Yeah.

There you go.

So it’s really in the name.

Vacuum bath.

Next one.

Last one.

Real fast.

Janna, half a sound bite.

This is Hector Salazar, who says this.

Can other universes influence or overlap with our own?

And is there any evidence that this might be happening?

This would be the parallel universe.

Yeah, very speculative, but if you consider a universe, let’s say, we’re floating on a three-dimensional membrane in a higher-dimensional space, and there’s another one of those floating also in the higher-dimensional space, parallel, or in some sense.

Now, do they both share this membrane you’re talking about?

No, they do not.

They can choose separate membranes.

So in that sense, we would call them universes.

And yes, it is possible that they have interacted in the past and that there would be some archaeological record of that or in the future.

But if they intersect, is there an intersection line, a three-dimensional line?

In which you live in both universes.

Like a party wall.

So technically, if you mean by universe, the galaxies and everything you see, and not the whole space time, then technically, yes, two universes, two membranes can interact and can coexist.

I want that.

I like the idea of living on the boundary between two universes.

Only if the people in the other universes aren’t a-holes.

And as long as the laws of physics there are the same as ours, because you don’t want to decompose into a puddle of goo.

Yeah, that would be bad.

That would be bad.

If the charge of the electron is different, bad, very bad, bad universe, stay away.

We got to call it quits there.

Always good to have you on, Janet.

It’s always fun to be here.

We don’t have you enough.

Thanks.

So much fun.

Janna Levin, Professor of Physics up at Columbia and Barnard College.

I am Neil deGrasse Tyson, your personal astrophysicist, signing off for StarTalk, bidding you, as always, to keep looking out.