Cosmic Queries – Light Sails & Quantum Scales

Neil deGrasse Tyson (0:00)

Chuck, that was a fun Cosmic Queries Grab Bag.

My favorite was the person who asked, what would the Cosmic Microwave Background be like when it happened? It's like, whoa, oh yeah. Take cover, is this lesson there?

Chuck Nice (0:16)

You know what Neil told him? Hey man, I was there when it happened, and I'll give you a firsthand account.

Neil deGrasse Tyson (0:22)

Coming up on StarTalk. Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now.

This is StarTalk Cosmic Queries, Potpourri Grab Bag Edition. Chuck, how are you doing, man?

Chuck Nice (0:49)

Doing great, Neil. That's right.

Neil deGrasse Tyson (0:51)

All right. I like the way you say Potpourri. Let me hear it.

Chuck Nice (0:53)

The Potpourri, which is my version of Galactic Gumball, you know?

Neil deGrasse Tyson (1:00)

Yeah, we don't know what to call this other than grab bag. Grab bag seems to work.

Chuck Nice (1:04)

Yeah, grab bag works.

Neil deGrasse Tyson (1:06)

And it's a fan favorite because people ask whatever the hell they want.

Chuck Nice (1:09)

Whatever you want.

Neil deGrasse Tyson (1:10)

All right, Chuck, so what's your first question?

Chuck Nice (1:12)

All right, here we go. Trisha Lynch says, Hello, Dr. Tyson and Lord Nice. This is Trisha from Beaverton, Oregon.

If the multiverse exists, how will we be able to tell where our universe ends and another universe begins? Well, thank you.

Neil deGrasse Tyson (1:36)

I like that. Interesting.

Well, there's several variations on the multiverse, and I only know a couple of them, but they're more than the number that I know. And they come out of sort of the mathematics of the early universe, as you shotgun marry quantum physics and general relativity with string theory and other sort of creative ideas in the early universe. So one version of the multiverse is there's one enormous grid of space time, and we're one bubble within that grid, okay?

Chuck Nice (2:15)

Okay.

Neil deGrasse Tyson (2:16)

The difference is these bubbles are separated from each other in a way that you cannot access the other bubble. At the end of our universe is wherever that is, but it would not overlap with another universe, even though all of these universes are expanding.

Chuck Nice (2:36)

If it's a bubble in the spherical sense of a bubble.

Neil deGrasse Tyson (2:40)

Yeah, sure.

Chuck Nice (2:41)

Then the universe ends where the universe begins. Where is the end of a bubble? Where is the end of a bubble?

Neil deGrasse Tyson (2:55)

So you might say that the edge of the bubble is where you begin your journey into the bubble universe.

Chuck Nice (3:02)

Exactly.

Neil deGrasse Tyson (3:03)

Is that an end or beginning?

Chuck Nice (3:05)

Is that an end or beginning? Right?

Neil deGrasse Tyson (3:06)

You know? I like that. I like that. Yeah. A legit reinterpretation of the information.

So all of these universes are out there, expanding and not overlapping. So that's a, by the way, on the possibility that they might have overlapped, there are experiments you can do with the cosmic microwave background. What you can do is you can look to see if one part of the cosmic microwave background looks statistically different from another part of the cosmic microwave background in a different direction. That could be somebody else's universe impinging on ours. That would show up in the statistical analysis of the microwave background. And people have done that experiment and looked for these signatures and haven't found them.

Chuck Nice (3:56)

Found enough and enough.

Neil deGrasse Tyson (3:58)

They found, yeah, there's nobody impinging on our statistical, on the statistics of our universe. And I say statistics of because the microwave background is a tapestry of fluctuations of temperature that existed in the early universe that is imprinted in microwaves that we can observe today. And if there's a different universe, it might have a different imprinting, and you'll be able to see that. You should be able to see that if there was some overlap, and we don't.

So that's one kind of multiverse. Another one is just a whole bubble separate from this grid of space-time that I presumably embedded in a higher dimension. And it's expanding, and we're expanding, and never the twain will meet. So plus it's possible, in fact, it's likely, given quantum physics, that the laws of physics are slightly different in one universe relative to another. And it would be extremely dangerous if you wanted to visit the other universe. Because you don't know, is the charge on the electron different? Will all your atoms fly apart, or will they collapse?