What are the properties of de Sitter space?

[momo666]

I am having a hard time finding information that I can understand on de Sitter space. One main question I have is if it is eternal.

Also, does the recent discovery of gravitational waves have any impact on it? I've seen mentions of de Sitter space in multiverse theories.

 

[Chalnoth]

1. De Sitter space is a space with no matter or radiation and a positive cosmological constant. This kind of space is static and eternal. It doesn't, however, describe the real universe, as the real universe has matter in it. But it may be a decent approximation of the far future of our universe.
2. The direct detection of gravity waves has no impact on this question.

 

[momo666]

Is this space purely theoretical? How do we know it exists?

 

[Chalnoth]

Is this space purely theoretical? How do we know it exists?

It's a purely theoretical construct.

 

[strangerep]

Is this space purely theoretical? How do we know it exists?

Well, all space is "purely theoretical". It's a construct that's useful for organizing perceived events.

As for de Sitter spacetime, some people advocate that de Sitter relativity should be the new "special relativity in the 21st century". Whereas Minkowski spacetime used to be regarded as what you get when there's no gravitating matter, the existence of a nonzero cosmological constant suggests that the correct spacetime with "no gravitating matter" is de Sitter, not Minkowski.

YMMV.