PAllen's latest activity

Frequently Doppler is used to define mutual rest, by absence of shift. Of course this is just one definition, but it is ONE. It...

The issue with this comparison is the at some point we agree there is no baldness. In the case of spectral shifts in GR, all the...

Sure, because in a free fall frame it is primarily Doppler.

Hopefully not beating a dead horse on this, consider any small region in GR. Then there is a class of phenomenon you would consider to...

Oh come on. All I was saying is that there is a possible way to look at such that the title is right. That doesn't mean your way of...

But being able to have density decrease everywhere is a very unusual geometric property for an infinite spacetime to have. I would...

It can become vaster per unit of stuff, everywhere. There are different metrics you can put on an infinite spacetime, and only some have...

And in SR, one ends up being a vector and the other a covector. It can be confusing ...

Hey, Luciano Rezzola is one of my favorite GR researchers! I’ll want to take a close look at these.

One can discuss the topology of limiting surfaces approaching a singularity. In that sense, the topology of the initial big bang...

Also, it should be noted that spherically symmetric nonrotating collapse to a BH per general relativity does predict unbounded density...

But that is part of the measuring device. In the continuum approximation, you can take the limit as charge approaches zero, voltage...

One other example is simply that if you charge metal ball or plate with static electricity, then you measure a potential difference...

Yes, I agree with you.

I don’t think that works. I tried that. Remember f is a function (hidden within r) of all 4 coordinates. That means zeta must be as...