Do quantum fluctuations actually occur in De Sitter space?

[TheQuestionGuy14]

A little while back I asked a question about quantum fluctuations, and I got some great answers.

Just recently, I stumbled upon a paper by Sean Carroll, which states that there isn't quantum fluctuations after all, in a De Sitter space in a vacuum state. He used this to argue against Boltzmann brains existing in the future when the universe reaches this De Sitter space stage.

I'm curious, is what Carroll is saying true? It makes sense, but it goes against what physicists have been saying for a long time.

Here's the paper: https://arxiv.org/abs/1405.0298

 

[eljose79]

Thank you for bringing up this interesting topic about quantum fluctuations and the recent paper by Sean Carroll. As a scientist in the field, I would like to offer my perspective on this issue.

First of all, it is important to understand that the concept of quantum fluctuations is a fundamental part of quantum mechanics. According to this theory, at the quantum level, particles and fields are constantly fluctuating and can spontaneously appear and disappear. This is a well-established phenomenon and has been observed in many experiments.

However, in the paper you mentioned, Carroll argues that in a De Sitter space in a vacuum state, these fluctuations do not occur. This is because in a De Sitter space, the expansion of the universe is accelerating, and this acceleration suppresses the formation of particles and fields. As a result, there are no quantum fluctuations in this scenario.

While this may seem to go against what physicists have been saying for a long time, it is important to note that this is a very specific scenario and does not negate the existence of quantum fluctuations in other situations. In fact, Carroll's argument is based on a hypothetical scenario of a De Sitter space in a vacuum state, which may not be applicable to our actual universe.

Furthermore, there have been other studies that suggest quantum fluctuations still occur in a De Sitter space, but they may be different from what we observe in our current universe. So, while Carroll's argument is thought-provoking, it is not a consensus among physicists.

In conclusion, the concept of quantum fluctuations is still a fundamental part of quantum mechanics, and it is important to continue studying and understanding it in various scenarios. I hope this helps clarify the issue for you.