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?
I’m guessing you started seeing things about the EM drive and reactionless thrust.
Unrah particles with wavelengths longer than the width of the universe kinda stuff.
I’m an engineer, with a great interest in physics.
I’m also a skeptic, so from my point of view. I would look at a similar scenario, that exists in nature.
Assume an asteroid is accelerating toward a black hole, does it radiate away the excess energy above expected level to account for the excess Unrah radiation it absorbs?
Does it only become apparent, when close to the event horizon, where it is masked by the other debris heating the asteroid?
I can’t give you an answer, but I would assume there is no free lunch. The Unruh energy would not exceed the energy to accelerate the craft.
An asteroid falling into a black hole is in free fall, it’s not accelerating.
There are lots of related questions about black holes and hawking radiation one can ask and the answer is we don’t know, we don’t have the physics to describe it yet.
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.