Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Do temporarily accelerated particles experience the Unruh effect? I think, they don't, because they don't see an apparent event horizon.

On the other hand, if the duration of the acceleration is long enough, this case should be approximated during this phase by the eternal accelerated particle. And this particle sees the Unruh effect.

share|cite|improve this question
up vote 3 down vote accepted

There is also an Unruh effect for not eternally accelerated observers! See Akhmedov, Singleton, "On the physical meaning of the Unruh effect", . There is even a derivation of Unruh effect for observers moving on a circle (which don't see an event horizon too) with a fascinating connection to the Sokolov-Ternov effect of high energy physics.

share|cite|improve this answer
Will the distribution of modes as observed by a finitely accelerated observer be thermal? – Prathyush Apr 3 '13 at 22:56
No, the spectrum observed by an detector on a circular path is not thermal. This comes from the form of the 2-point-function for circular motion, see eq. 5 in above mentioned paper. It is quite different from the 2-point-function of eternal linear acceleration, which is strongly connected to a Planckian thermal distribution. – AGP Apr 4 '13 at 8:48

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.