So, I was reading about the Unruh effect. In short, if I understood correctly, it is about a constantly accelerating observer finding particles in vacuum that an inertial (non-accelerating) observer wouldn’t, and relatedly, measuring a higher temperature there than an inertial observer would. This is due to a combination of quantum and relativistic phenomena. There even seems to be recent empirical support for this, but as I was reading about it, I accidentally stepped into some pseudoscience, which left me in an emotional state where I find everything suspicious.
Anyway, even though I technically am a physicist, this is far from my area of expertise. I came up with a thought experiment and would like to ask a couple of questions related to it.
Let’s imagine a spacecraft that does a little trip where it goes into open space accelerating enormously, then stops and comes back. My first question is this: would it be (theoretically) possible for the spacecraft during the acceleration to capture some of those particles that from an inertial perspective don’t even seem to exist, store them and bring them back as a very concrete evidence of the Unruh effect? If not, why not?
Another question or two: is my intuition correct when I think that if those collected particles were converted into energy, it would in no situation be possible to gather more energy this way than would be spent in the process of accelerating the spacecraft etc? If yes, could one in some sense say that the energy put into the acceleration is what created those particles in the first place?
The things I ran into were Nassim Haramein and his “International Space Federation” claiming to have combined quantum mechanics and general relativism and aiming to use that for harvesting infinite free energy from vacuum or something like that (and on the side also claiming that consciousness is a fundamental property of physics, of course).
There are about three practical ways to make measurements related to Unruh effect, I think. Black holes are one way, as Hawking radiation is an equivalent phenomenon. Another thing is studying some classical systems with equivalent phenomena, like sound waves in some fluids, IIRC. The third way is the particle accelerator approach used in the paper linked to in another comment. The experiment I suggested would be utterly impractical to actually perform, I think.