Cosmic Queries – Theoretical Physics

Welcome to StarTalk, your place in the universe where science and pop culture collide.

StarTalk begins right now.

This is StarTalk.

I’m Neil deGrasse Tyson, your personal astrophysicist, and today is a Cosmic Queries edition, Theoretical Physics.

Chuck, always good to have you.

Always good to be here, Neil.

I mean, theoretically.

This is StarTalk in the Coronaverse.

You’re sitting there in, I guess, in your Jersey home.

Is that right?

That is correct, sir.

I am the Sarah Palin of New Jersey.

I can see New York from my house.

I’m in an undisclosed location somewhere.

Some government underground bunker.

Theoretical physics, I know probably 10% of what I should to cover this myself.

So we got to bring in the big brains for this.

That takes us to our close friend of StarTalk, physicist, cosmologist, Janna Levin.

Janna.

Hey, man.

Welcome back.

Good to see you through the ether.

Through the ether, yeah.

I just want to get your title straight again.

Professor of Physics and Astronomy at Barnard College.

Does that mean you get double income for that?

Oh, yeah.

Oh, yeah.

Oh, no.

That’s a good, but I should bring that to the provost.

Yeah.

No, I mean, we’re pretty fluid in our subject matter.

We can move around.

All right.

Was that perhaps the subject should have never been divided in the first place?

Well, that’s a good point, for sure.

In fact, an interesting point that even, as you well know, Neil, the word scientist is fairly modern.

Like even the idea of separating science from other forms of thinking about the world or meditating on the world is fairly recent.

Yeah, I think that we all used to just be called natural philosophers in the day.

Actually, I’m going to go with scientist is better.

Yeah, you like it better?

I’m just saying natural philosopher sounds like a BS artist if you talk to them.

I mean, I’m just saying.

So what do you do for a living?

Oh, I’m a natural philosopher.

Oh, a BSer.

Oh, no, you’re unemployed.

Well, check, you got the questions.

I do, indeed.

Actually, I’m going to lead off with a question.

Janet, we did a special Patreon Q&A a few days ago, and I don’t know if it’s posted yet.

But I answered a question, and when I finished giving the answer, I was disappointed in my answer.

And I just thought maybe you could come give me backup on this.

So the question was, as we know, if you fall in towards a black hole, if you observe that phenomenon, it will slow down.

And it, in fact, will appear to stop just outside the event horizon.

And so whereas if you are that, thank you, Chuck, Chuck’s moving real slow right now.

So if, and so whereas if you are the person falling, it just happens in real time to you.

You don’t think about it at all.

Yeah.

All right.

If we, the observers of things falling into a black hole, see everything freeze at the event horizon, how does the black hole ever gain mass?

As far as our measuring devices would ever.

Yeah.

It’s, it’s actually a little bit of a subtle question, but for a while it’s so subtle that for a while people used to call them frozen stars because they thought that they just sort of froze and never actually became black holes.

But the argument is actually that if I’m falling into a black hole, I have a little bit of mass relative to the mass of the black hole.

And so I have my own gravitational field.

And as I get epsilon, very, very close to the event horizon, the black hole, I actually deform the event horizon so that it bubbles around me.

And I actually fall in, in a finite time, even to somebody far away, even to somebody far away, they would have to say, so if I threw in something big like a star or another black hole, you will see the event horizons absolutely bubble, deform, enveloping each other in a finite time because of the curved space time of the other object, deforming the event horizon, and it will all happen before your eyes.

So what you’re saying is you have your own, not your own event horizon, but you have your own deformation in this, in the fabric of space time.

Yeah.

And that will deform the event horizon for a second until it absorbs me.

And then, you know, black holes are perfect.

They will shed any of those imperfections very, very quickly.

But for a second, it will deform, you’ll get absorbed, and then it’ll usually send out some gravitational waves and ring down.

Okay.

It’s like hitting a tennis ball with an invisible racket.

I like it.

So that’s why, like when we heard the two black holes collide, and it happened and it was over, and one black hole formed, it didn’t take an infinite amount of time.

And that’s because both black holes were so big that their own gravitational disturbance of space-time was so strong that it actually happens to us.

We really see it.

So they don’t freeze into their own event horizons.

Right.

It’s really weird.

So the objects are both so big, and you can actually see in the simulations of the event horizon that it looks like a big barbell, it really deforms.

Yeah.

Dumbbell, dumbbell.

We’ve never been to the gym.

I’m not much of a weightlifter.

Yeah.

And so it happens fast, actually, even to us from far away.

Well, thank you for clarifying that, because I did not make that part of this evident in my answer.

And Chuck, maybe we can put some indicator back to this posting from the Patreon Q&A that we did just recently.

Yeah.

Yeah.

Man, that is really cool stuff, though.

All right.

Let’s go to Patreon.

Speaking of Patreon, we always start with the Patreon patron, because Patreon people support us financially.

Thank you, guys.

And this is Cody Klebowski, who says, if time is relative to a person’s experience of it, is there a universal base time, or is time only relative?

Is there a Greenwich Mean Time for the universe?

Yeah.

Yeah.

We’re standard time.

What have you done with it?

Well, actually, when we say things like the universe is 13.8 billion years old, we are referencing a particular cosmic time that on average is about the same for every galaxy.

So if you are not moving relative to the expansion of the universe, the time you will measure is this cosmic time we talk about.

So, it’s not 13.8 billion years just for us on Earth and a completely different age for somebody else in a different galaxy.

As long as the galaxy is relatively slow moving compared to the expansion of the universe, it’s just kind of going along with things for the ride, then this is your equivalent kind of mean time.

It’s a cosmic time that we can all agree on.

What you’re saying is because galaxies have motion among other galaxies.

Yeah.

So, that has nothing to do with the expanding universe.

Yeah.

But this motion, you can, if they go really fast or slow, there’d be a time shift, a relative time shift, but that’s a detail relative to the…

It’s a tiny, small, small correction, basically.

And if you were traveling relative to the expansion of the universe, you’re the speed of light for the entire history of the universe, you would certainly disagree about the age of the universe.

You would not be saying, it’s roughly 14 billion years ago.

But no galaxy is doing that.

No galaxy is doing that.

And in fact, even if they were going fast at once, there’s a lot of that cosmic expansion slows them down.

They tend to slow…

So all the galaxies tend to kind of get very slow moving relative to the expansion of the universe.

So what about the fact that, as I see farther away, the speed of the galaxy receding from me is getting greater and greater?

Yeah.

It’s a great question.

Yeah.

So there’s some distance at which it might be receding at the speed of light.

Yeah.

For me, I should see no time pass for that object.

Is that not correct?

No.

So actually what’s happening is the object itself is not moving in some sense relative to the expansion of the universe at all.

It’s the space that’s stretching between us.

And so the space is stretching between us faster than the speed of light.

But in most circumstances, a light beam can just still make its way over to us eventually if you wait long enough.

And so if the universe is slowing down, every galaxy will eventually be visible to us as we wait long enough.

But if the universe is actually accelerating, which is what it seems to be doing right now, there will be a distance beyond which the light will not be able to outrace the expansion of the universe.

And we will never see those galaxies.

And it will be like having an event horizon like you do for a black hole will be a cosmic event horizon where we are never to see or know or be able to communicate with what goes on beyond that distance.

Because it is receding faster than the light can overcome the stretching of the space.

That’s right.

So the light is racing and racing and racing, but the space is stretching faster and it’s never going to overcome.

Okay, so the one where it is just exactly at the expansion rate for the light to exactly compensate for the stretching of the universe.

If we see that light, that’s going to be frozen, isn’t it?

Oh, so yes.

In the same way that there is.

So if it’s accelerating and there’s something and that happens and there is something, it’s an event horizon.

Indeed, there is a last signal we will get.

So, if something is just on this side of that event horizon, we’ll see it in the infinite future.

And if something’s just on the other side, the light will just seem to hover there, will never seem to get to us.

Okay, but will we see it reckon time differently from how we reckon time?

Well, it depends on what you mean by it there.

The galaxy itself could be measuring the same cosmic time.

That’s what I was wondering.

But light, you know, almost registers no passage of time.

Yeah, no passage of time, right?

Yeah.

But the galaxy itself, as long as it was just being dragged along with the expansion, should agree with us that the universe is about 14 billion years old.

I think.

So there you go.

That’s it.

There it is.

Good light, don’t crack.

You’re such a nut, Chuck.

Oh, did you notice I’m wearing my, I meant to show you this earlier.

It’s my space shuttle, Bolo.

Oh, very nice.

I always have to wear something themed for you, Neil.

Thank you.

Thank you.

It’s quarantine.

There’s only so much we can do.

We’ve got another.

Because the other person’s name was Flavie Flap.

All right, Peter Jacobs wants to know this.

Peter Jacobs says, is energy a thing or is it just a relationship between things?

And he’s coming to us from Queensland, Australia.

Good day, mate.

Good day, mate.

Good day.

And actually, we have to take a break right now.

And we’ll come back to that because that’s an excellent question.

I think it has a deeper, broader significance.

The measurement of anything, does it only have meaning with regard to something else?

Can it have absolute meaning without regard to whoever is looking at it or measuring it?

So when we come back, we will pick up Cosmic Queries theoretical physics edition with our friend and my colleague, Janna Levin.

Bye We’re back, Cosmic Queries, Theoretical Physics Division.

Ooh.

But I need help, and we got help, and we didn’t have to reach too far.

Janna Levin, Janna, always good to have you.

Always good to be here.

Here.

Got the question.

Here, yeah, here.

Here.

Yeah, exactly.

We’re all here, and yeah.

So Peter Jacobs, before the break, asked if energy a thing, is energy a thing?

Or is it just a relationship between things?

Ooh, I love that.

Janna, where does that come from?

Where’s that going?

I don’t know.

I thought you were gonna have a prompt, but I’ll do a quick one, and then I’d love to hear your opinion.

So for instance, if I’m sitting still in space, but I’m moving in time, I still have some energy.

That’s what Einstein taught us.

I have a kinetic energy in time in some sense because of my motion in time.

And that’s my E equals MC squared energy.

And that’s my basic, you can actually unambiguously break my atoms apart and get that energy out and blow things up and have real impact.

Without reference to anything else.

Without reference to anything else.

But if we’re astronauts floating in space and I think I’m just moving in time with my kinetic energy equals MC squared in time, but you go whizzing past me, you think I’m moving past you.

And so now you think I have a relative kinetic energy that I don’t think I have.

That’s what my motion in space.

So it’s kind of both.

Wow.

Kind of both.

Okay, so in other words, okay, the way it wouldn’t be both is if the question were asked whether mass energy was something relative to something else.

Because I can measure you to have a different amount of kinetic energy in time versus mass.

I can say I have no kinetic energy in space and you can say I have a lot of kinetic energy in space because you just saw me fly by.

And we both, because I was flying by you, but how would I know?

Right.

Right.

So, but if I add up your time energy and your spatial energy, that should be a constant no matter what.

So that’s an interesting question.

What’s actually constant is a combination of my energy and my spatial momentum, my kinetic energy.

Yes, a combination of the squares weirdly, of my energy and my in time and my kinetic energy, that that will be the same, even though we’ll disagree about what’s what.

We have a way to calculate what would be the same for every observer onto you.

That’s right.

And so it’s interesting.

So like, let’s say you tell me that you’re looking three feet to your left.

I might disagree that it’s to your left.

I might say it’s to my left or I’m sorry, my right, but we’re gonna agree on the overall combination.

And so it’s similar with like time energy and physical, spatial, kinetic energy.

We’re gonna disagree on which piece, if it’s how it’s distributed, but we’re gonna agree on a combination.

That is really good.

By the way, I forgot all about that formula.

We have the squares of the energies.

I just like…

E squared minus P squared.

Yeah, exactly.

Chuck fell left out a little bit on that.

I feel like we could keep going, but we’d regret the rabbit hole.

And that is a rabbit hole, man, for real.

But that’s a very cool question.

Thank you, Peter.

Let’s go to Facebook and Steve Cotton.

Steve says, will quantum entanglement allow for FTL or instant communication to exist between worlds with light years of distance between them?

This is clearly a StarTalk fan.

I mean, a Star Trek fan who knows about subspace, which is how they get around talking to people in almost real time, even though they’re in different galaxies.

They have this thing called subspace.

And what’s it mean?

Nothing.

It means…

Wait, wait, wait, Chuck, just to be clear, you’re laughing at it, but at least they thought about that problem and came up with a sci-fi solution to it.

All right, okay, I’m gonna give you that.

Listen, you know what?

I gotta give it to you.

That is actually, that is a seriously salient consideration.

I gotta give it to you.

You’re right.

Yeah.

All right.

So anyway, so anyway, go ahead.

So Janna, let me read.

Okay, well quantum entanglement allow for FTL or instant communication to exist between worlds with light years or distances between them.

So, Janna, let me just ask you something.

I wanna prep this and ask you, do you even need quantum entanglement if you have wormholes?

No, you don’t need quantum entanglement if you have wormholes.

And wormhole, you can actually put material things through the wormhole.

And I just open a portal and it’s right there in the back door.

Yeah, and Neil, as I know you’ve made the point before, it’s not that it’s faster than light travel, you’ve just found a shortcut.

It’s like somebody going between New York and New Jersey by going all the way around the globe, right?

And thinking it’s really far away and you tell them, actually, you can just go this way, the shorter way.

So the wormhole gives you a shorter way.

Yeah, so the wormhole makes a veritable shortcut where you travel slower than the speed of light and you just have a shorter distance to go.

Right, and you’re slower than the speed of light while you’re in the wormhole.

Totally, yeah.

Yeah, and the other thing that I know we’ve talked about before is this warp drive idea, which is that space can expand faster than the speed of light and contract faster than the speed of light without violating special relativity or any of those laws.

So you can also bring something closer, take a short step across the pond and then push it further away again by just expanding the space.

This would be awesome control over the space-time continuum to accomplish this.

Awesome control.

Okay, so what’s more likely to happen?

That we perfect quantum entanglement faster than light communication?

Yeah.

Or that we open up wormholes throughout the galaxy?

Quantum entanglement is actually happening.

Like we do it in the lab.

I mean, we don’t do it in the scale that the question was asked from one galaxy to another because we also can’t get our own selves to another galaxy.

But we can definitely do this experiment where we throw things faster than, we throw information faster than the speed of light across the lab.

That’s amazing.

I mean, but, I mean…

It is amazing.

I mean, I even think it’s amazing.

Like I know the theory and then you find out somebody’s done it in the lab and you’re like, what?

I mean, because the implications there are kind of like, if you look at all of our telecommunications today, it started with one quick, one sentence, you know, Watson come here.

So, think about, and the dude was literally in the next room and they thought that was like, oh my God, it’s amazing.

Oh, he just called me in the, I mean, he could have actually went like this, Watson, and Watson, okay?

And it would have been more effective.

It would have been more effective.

So, honestly, that’s what you’re saying is just mind blowing.

But Chuck, don’t you think we’re so unappreciative of how amazing this is right now?

Like, I don’t even know where to look.

I got so many squares to look at on my screen.

I don’t even know, like I’m looking all over the place, but we’re taking so for granted that this is, we’re doing this is amazing.

This is phenomenal.

We’re just used to it.

Wow.

Yeah.

So now a quick question, Janna, is what’s the difference, functional difference, between a collapsed wave function in the quantum entanglement and that information is shared instantly, not just faster than the speed of light, instantly.

What’s in between that and-

Oh, but see, here’s, ooh, sorry, I don’t mean to interrupt you, but instantly according to whom?

So there is some very tricky things about, because in simultaneity is relative.

All right, okay.

Show’s over, show’s over.

I gotta go.

I can’t, dropping my headphones doesn’t seem like quite as dramatic.

And I am not dropping this microphone.

Do not drop them.

Okay, okay, sorry, Neil.

Okay, go ahead, what you were saying.

Yeah, so it’s instantaneous according to the person who does the observation.

It’s like a tunneling, a particle is over here and there’s a barrier of any kind and there’s a chance it’ll just show up on the other side of that barrier.

Yeah.

But when it does so, that happens instantly.

Yeah, it does so instantly, but you can kind of calculate the natural timescale for it to happen.

Gotcha, okay.

But it doesn’t mean it doesn’t happen instantly, but it does mean like, oh, do I have to wait for a Googleplex of years for this to happen?

Or is it likely to happen in a year or in a second?

And you can do experiments where it’s more likely to happen in a short period of time.

So if you do a whole bunch of them, if you put a whole bunch of particles in a box in your laboratory, you’ll see a whole bunch tunnel through on the other side at about a second.

And so you’re right, it’s still instantaneous, but it’s just what’s the likelihood of it happening in a certain period of time.

Now, I gotta throw this in here, just I’m being Professor Neil in this moment, but we knew for the longest time that if there were ever gonna undergo nuclear fusion anywhere in the universe, that the centers of stars would be the place that that would have to happen.

So what people did was calculate the temperature in the centers of stars, and we’re getting millions of degrees, okay?

Just do the thermodynamics of that.

You run the quantum calculation, sorry, you run the calculation of is that a high enough temperature for protons to overcome their natural repulsion?

You have two positive charges.

They don’t wanna get close to each other.

But to fuse them, you gotta bring them together to turn them into another element.

So can you overcome it?

They did the math, and they could not overcome the repulsion.

So they said the centers of stars can’t be the place where this happens, because we did the math, and we know thermodynamics.

And then quantum physics gets discovered, and then we learn about tunneling.

And then we learn that at the temperatures in the centers of the stars, the proton can disappear from here and show up right next to the other proton, bypassing the electrical barrier.

When it bypasses the barrier, it fuses, you turn hydrogen into helium.

And it was the tunneling that even enabled anybody to accept that stars could be the source of helium.

I just had to throw it.

The temperature is not high enough.

I can’t believe, why have you never told me this story before?

Well, it’s not really a story, but still.

It’s sort of a story.

By the way, that is just, so the original calculations led them to believe that this is not the place that it could actually happen.

But, in all fairness, Arthur Eddington, I think it was him, was one of the great towering theoretical physicists at the turn of the century, 100 years ago.

Someone came up to him and said, do you see, it’s impossible, you can’t overcome this electrical repulsion.

And he said, I don’t care if there’s any place in the universe where this is gonna happen at all, it’s gonna be in the center of the star we’re gonna find out one day.

Wow.

Yeah, I mean, you can kind of, you know, when you get in a zone and your numbers are off by not enough for you to abandon the idea.

They’re off by enough for you to know you haven’t understood everything, but not enough for you to abandon the idea.

Right, so you stick with it.

Wow, that is super.

Chuck, it wasn’t in no basis, I’m sorry.

Super fascinating though.

I mean, that’s, God, that’s so cool.

All right, here we go.

Fred Pibonesa, whatever, Fred.

Ever apply to work at the United Nations, okay?

I know, I will start many global incidents.

Like, what you calling me?

Anyway.

Chuck was doing a translation.

You gotta let him, cut him from slack.

He says, what is space made of?

Wow, because we hear about the fabric of space.

What is that fabric?

Ooh, okay, Chuck.

We don’t have time to answer that until the next break.

I do like that.

So, love that question and I know Janna loves it too.

There’s a lot that’s gonna come out of this one.

We’re gonna take a quick break from StarTalk Cosmic Queries Theoretical Physics Edition.

Hey, we’d like to give a Patreon shout out to the following Patreon patrons, Marcus Guerra and Mahmoud Hyatt.

Guys, thanks so much for the gravity assist without you.

We could not do this.

And for anyone else who would like their very own Patreon shout out, please go to patreon.com/startalkradio and support us.

We’re back for the third and final segment of StarTalk Cosmic Queries, Theoretical Physics Edition.

I love it.

We should do this more often, Chuck.

Man, it’s really good, really good.

Of course I need help for that.

Janna Levin, Janna.

So Chuck, we left off.

Vanessa, right?

Nope, yep.

Ha ha ha.

Nope, it’s…

Pio Vasana, that’s what it is.

Pio Vasana, okay.

Sorry, Fred.

Wait, Pio Vasana, but his first name is Fred.

Ha ha ha.

It’s probably Federico or Frederico, and they just went with Fred.

He’s making it easier for Chuck.

Anyway, Fred wants to know this.

What is space made of?

So everybody talks about the fabric of space.

What’s that fabric?

What is it?

And let me lead into you here, Janna.

So we like to think of, just naively, that, okay, there’s earth and then there’s air, and then where there’s no air, there’s empty space.

So we have a word for what we think contains nothing.

So holding aside stray atmospheric particles that might be floating up there, that’s not what we were talking about here.

Let’s talk about what’s between the particles.

So give me the most empty space you can, and I’ll talk about it.

Well, I’m going to give an answer that I don’t 100% understand or believe, okay?

No, wait.

Janna, I get that from Chuck all the time.

So right now…

The answer is he neither understands nor believes, Chuck’s mouth all the time.

That’s it.

That’s where I’m a Viking.

I think that this is…

I would say this.

I think this is how we can understand it now, and that our understanding will change.

So right now, I know that my room is full of electric and magnetic fields, and I cannot see them, but they make a fabric of the electromagnetic fields in the universe.

They’re just there.

I know they’re there because I’m looking at you right now on an electronic instrument, and this is just a reality that the fields are here, even though my eyes aren’t good detectors of them, my fingers aren’t good detectors of them, and I don’t notice them.

Just to be clear, the fact that light can move through empty space from wherever it started to its destination, your retina, being space is permeated by electromagnetic energy.

And we can see those, we can see that version of the electromagnetic energy, the one that oscillates at just the right frequency that my eyes evolved to be able to detect, but I can’t see the ones that my phone’s detecting.

Like when my phone goes off, I don’t see like flashes.

Versus microwave light.

Yeah, or even not light at all, like steady electric fields.

But yes, most of them are usually light signals.

But right now, there’s probably just a steady electric field in this room that permeates a whole space.

It’s just from God knows what.

And I can’t see it, feel it, touch it, because I’m my, you know, it doesn’t resonate with my particles very well.

So I can say that there are fields that permeate the universe and they make a fabric of that field of the electromagnetic field.

I would say in analogy, there is a gravitational field and the gravitational field is analogous to a curved space-time.

It describes the curved space-time.

The gravitational field defines the shape of space-time and my eyes are not good detectors of it and my hands don’t touch it, but I fall along it.

If I were to jump off my chair, I would fall along this gravitational field.

And so that is the fabric of space in some sense.

All right, but Janna, I think that’s a cop-out answer because…

Fisty Cuffs.

Oh, sure, you’re far away.

Say that to me in person.

No, I’ve totally followed the answer, but let me take you a step forward, push you.

Chuck, you are describing what happens to be in the empty space of the universe in which we live.

Can you imagine empty space through which there is no electromagnetic field and where there is no curvature from matter?

I cannot imagine space as separated from a gravitational field, including a flat, empty gravitational field.

But when we learn general relativity, one of the ways you start there is imagine a flat space with no matter.

Yeah, I would still call that a gravitational field.

I would just call it a flat, straight, very boring gravitational field with no sources of gravity in it.

I feel like you.

So let me put it this way, it doesn’t mean it doesn’t have space in it.

So let me put it this way.

You’re trying to give the existence of space.

You try to credit the existence of space.

I would say that’s something that happens to be in it.

No, no, I would say it this way.

I would say there are gravitational fields even with zero sources.

So I would put it that way.

So I would say I take Einstein’s equations, which as you said, says put in a source, a sun, a black hole, a moon, whatever, and you will find the curvature in the shape of space-time, also known as a gravitational field.

I can take Einstein’s equations and put in zero sources and find as a solution a gravitational field that is just extremely plain, where things travel on straight lines.

Okay.

So in other words, it’s the ground state or the lowest energy state of the field, and that there is no state of the field where space doesn’t exist.

It just isn’t the ground state.

It is the ground state.

I know.

Wait, so what about a universe that pops out in the multiverse that has no matter and no energy in it?

Well, are you asking what it would be?

Well, this is, you know, it would be in principle, if there are no observers, it becomes one of those questions of there’s no one to measure time, there’s no passage of time, there’s no experience of space.

It’s got to have something in it to even ask the questions.

So, all right.

But a universe that pops out of existence with nothing in it could just be a plain old flat space with nothing in it.

I mean, I don’t know, but you’re really you’re talking about something where there’s no meaning to the passage of time.

So how about, no, let’s get quantum on this.

I’ve read about and I just, as you said earlier, I accept it because people I trust have thought about this and are far better experts at quantum physics than I am, describe space as a seething soup of particles popping in and out of existence.

Yeah.

What’s your matter?

Anti-matter particle pairs.

Yeah.

But what is a virtual particle?

So this goes back to the Heisenberg uncertainty principle, which is really initiates the whole quantum revolution and the uncertainty principle.

Heisenberg, not from Breaking Bad, just to be clear.

Oh, no.

But do you think they were fans of physics?

But Heisenberg, German physicist who realized that there is a level of uncertainty to how much we can know.

But the real impact of what Heisenberg said is he said in some sense, I can never know a particle is precisely there.

So I can never know a particle is not there.

So if I have empty space, the uncertainty principle ensures that I cannot declare it to have nothing in it because I can never say with certainty a particle isn’t there.

In the same way that I can’t say for certainty a particle is there.

And so virtual particles are in some sense a manifestation of this fundamental uncertainty.

You cannot have an absolute vacuum empty state.

It cannot be.

Uncertainty doesn’t allow it.

It says that there is always some possibility.

How do you measure it?

Oh, you know what?

We’ve never measured a vacuum fluctuation.

And this is a really interesting, really interesting point, which is something I didn’t appreciate until fairly recently.

But we do see effects like there’s something called the Casimir effect.

So the Casimir effect where we put two metal plates together and it’s a way of limiting the number of vacuum states that can exist because of these boundaries.

It’s sort of like excluding all, not every possibility is allowed.

And it creates a difference in the vacuum fluctuations on one side of the plates than on the other side of the plates.

And that creates a pressure differential.

And you can actually measure it.

So I’ve forgotten about that Casimir effect.

Yeah.

So as I understand it, you have to, you need very flat plates, very parallel.

And they have to be separated from each other on the level of the wavelength of the, of the virtual particles themselves.

Right.

It’s a very subtle, small, small detail, very fascinating experiment.

And when you do that, they want to actually pull together with a force, a new force that just shows up because of this.

And it’s like saying the quantum pressure of the fluctuations on one side exceeds the quantum pressure of the fluctuations on the other side.

Because you’ve made it impossible for some states to exist between these boundaries, basically.

But it’s not exactly a direct measurement.

You don’t measure a virtual particle.

And so in some subtle sense, it’s a beautiful, indirect measurement.

But we can’t be like, oh, I just saw a particle pop into existence and disappear again.

So basically what you’re saying for Fred is that there can never be nothing.

There can never be nothing.

There can never be nothing.

That’s basically what it comes down to.

Yeah.

Yeah.

So not even nothing has nothing.

Nothing.

Right.

Nothing has nothing.

Nothing is something.

Which is one of the arguments that…

By the way, I keep trying to tell my wife that.

It’s one of the arguments for dark energy is that what dark energy is, and it’s connected to the two questions, that what dark energy is…

But that mysterious pressure in the vacuum of space.

It’s the mysterious pressure in the vacuum of space from quantum behaviors, and it’s because even in an empty flat space, the universe that you asked about, Neil, there is a gravitational field, and the gravitational field has an energy associated with it, and it’s the energy associated with the quantum fluctuations.

Wow.

God.

I’m exhausted.

We got to do more theoretical physics.

I love this.

I love theoretical physics.

It’s amazing.

This is crazy stuff.

This is crazy.

I got to tell you the truth.

I am so sorry that I spent so much of my young life doing drugs.

I could have been doing this.

This is just as good.

I could have been easily.

Here I am hanging out with the stupid people who want to smoke weed and drink.

I should have been hanging out with the doggone physicists.

I know, man.

That’s how we roll.

Yeah, always great to have you on.

Always fun to be on, guys.

We need more installments of theoretical physics.

Anytime and everyone hang in there.

It’s good to see you all.

Thank you.

In the Coronaverse, Chuck.

In the Coronaverse.

A pleasure.

Stay safe, guys.

All right.

Neil deGrasse Tyson, your personal astrophysicist signing off from Cosmic Queries theoretical physics edition.

As always, keep looking up.