PeterDonis's latest activity

Where here "expanding" means "has a positive expansion scalar", which is an invariant property of a congruence.

Why do you think this is "worth drawing a line under"?

Looks ok now, yes.

Testing: ##p = w \rho##.

I'm having a somewhat different problem: whatever is going on in the editor changes my LaTeX to symbols like those from the "insert...

It's a theorem about spacetime models using General Relativity. Such models can include stress-energy that has an equation of state that...

Can you revert to a previous version that is known not to have this problem?

I've already explained that: anything with an equation of state ##p = w \rho## where ##w < −1/3## violates the energy conditions that...

Not exactly. ##w## is the ratio of pressure to density. For the simplest model of inflation (which works just like a cosmological...

https://www.physicsforums.com/forums/sci-fi-writing-and-world-building.220/ :wink:

That shouldn't be possible with a cosmological constant, because the energy density of matter and radiation can only decrease with...

Who said the superposition had to be equal?

You don't have to. You can rescale your length scale to match the expansion - this is called co-moving coordinates. And then you can...

Thanks, that makes it much clearer what experiment you're talking about. Unfortunately, your OP doesn't really give a good description...

Where? Please give a reference.