Casimir effect

In some cases, changing the boundaries of space time actually reduces the number of particles.

For example, in the Casimir effect.

Now, we've already seen how this effect reduces the energy of the vacuum between conducting plates.

In upcoming episodes, we'll apply these ideas to finally understand Unruh and Hawking radiation.

But in the real world, it doesn't seem like it's possible.

Now, I will say, and some viewers watching this video might point out and say, "Well, what about the Casimir effect?" Are you familiar with the Casimir effect, Lucas?

Uh, no.

So it's an-

So it's an interesting phenomena where if you put two plates really close to each other in a vacuum, they will actually feel a force pulling them together, and the explanation for that is that there's actually negative vacuum energy basically between them, and it causes the outside, um, to have a positive force, and they fall in together.

So you basically get a region of space of negative energy density.

And so some people try to take the Casimir effect and extrapolate that and say, "Well, that's proof that negative energy density regions can exist," and therefore you can extrapolate and say, "Well, we can then do this on a much higher scale to stabilize wormholes." The issue is, as far as we can tell, yes, you can have very short-lived, very small areas of negative energy density, but that seems to be the extent.

Quantum mechanics seems to put a limit on how big that area can be and how long it can last.

Eric Davis wrote a paper in April 2010 reviewing the same Morris-Thorn idea.

It confirms that general relativity permits such geometries and that tiny amounts of negative energy appear in the so-called Casimir effect, and squeezed vacuum states the quantities though of exotic matter needed for a stable spacecraft sized throat are far beyond what us mere petty humans are capable of casey so whilst we like the idea frankly at the moment it's not possible Where I do think it's quite exciting about Interstellar is the concept of future humans assisting the human race.

I'm really drawn to the ideas in Interstellar, and I do wonder sometimes whether Chris Nolan had a quiet word in his ear from someone in the Defense Department, because obviously one of the prevailing theories that's pushed very, very hard by a lot of researchers is the idea that whatever the phenomenon is, It might be us humans or some variant, genetic variant of us humans from the future and likely in another dimension.

They're worthy ideas, but Casey, my friend, at the moment, they're not scientifically possible.

void.

And it's called the Casimir effect.

So how can nothingness squeeze these two things together? Well, there has to be something there, right?

So

Now, unfortunately, we don't know of any particle with negative mass, but physics also doesn't prohibit one either, and hence such a particle would be described as exotic matter.

The Casimir effect is a well-known example of a negative energy pressure caused by the quantum vacuum effect between two very close plates and it has been the lifeline of hope for many warp optimists.

However, it's important to note that this is really a negative relative to the background vacuum energy.

If you took that vacuum energy away, there'd be no negative, so it's unclear whether this could be utilized for warping space.