PeterDonis's latest activity

No worries, post as you can. I hope you feel better soon.

Yes. Not "never". Just not in the last two billion years. Inflation does cause accelerated expansion, yes. In our best current model...

For reference, this paper looks like it has a good discussion of the 1965 Penrose singularity theorem: https://arxiv.org/abs/1410.5226

Sort of. It can apply to an expanding universe that is only dark energy dominated after a certain time, but not before that. That is...

The "Einstein's equations hold" part is "general relativity is valid". The "zero or negative cosmological constant" is part of the...

As far as I know, Hawking and Penrose didn't publish any papers together prior to the 1970 paper. Penrose published a paper in 1965...

Not in the 1970 theorem, no. Not in the 1970 theorem, no. Not in the 1970 theorem, no. Yes--the technical assumption is that the...

Moderator's note: A question about the assumptions of the 1970 Hawking-Penrose singularity theorem has been spun off into its own thread...

Because the inner product of an inertial world line's four velocity and any of the Killing fields is constant.

For your first assumption, that's true. For your second assumption, that the topology allows for a global inertial chart, why do you...

Pish posh. LotR is formative reading - required reading at least thrice. (And I'm not even a fantasy reader). It is the benchmark: All...

Oh boy I finally got to watch season 2. What a fabulous... mess. I can say that: I liked most of the fabricated new plots related to...

I think the summary in Sabine Hossenfelder's new video is excellent. Many important points made, I have bolded two at the end that...

Moderator's note: Thread reopened.

Note that while the article does focus on semiconductors, the first example it gives of a band gap, in the figure at the top of the...