PAllen's latest activity

To me, the idea is that formalizing the notion of global isotropy and homogeneity leads to both topological constraints and geometric...

It seems to me that global homogeneity and isotropy, formalized as requiring the product of R and a maximally symmetric, homeneous...

I have bumped into problems that are trivial given the assumption that there is a well defined answer, but more tedious if you don't...

In general, no. We can choose any coordinate system we please according to whatever amuses us, and there's no reason that the...

Of course you can look at it either way. Another statement is that Minkowski spacetime is the analytic continuation of the geodesically...

Also, in the other thread you thread, you said "No, that's not Minkowski coordinates, that's Milne coordinates. You can't put the...

I think you are missing my point. We start with just topology, no metric. The topology we start will is all of ##R^4##. In one case, we...

Correct. It’s occurs to me that there is another way to look at this that strongly justifies treating the Milne spacetime as a...

[Moderator's note: Spin-off from another thread due to question change. Edited to remove content specific to the other thread.] You can...

Thanks.

A better wording is simply that the time coordinate in Milne coordinates is different than the time coordinate in standard Minkowski...

I think my objection to the utility of simultaneity is its use at large scales, rather than small. Tangents and normals are local...

In geometry and Riemannian geometry, one uses tangents to curves and normals to curves. So, in the Minkowskian spacetime geometry of...

Well, some philosophers of foundations of physics use math fully equal to any theoretical physicist. Of course, you can “claim them” as...

Good afternoon, This is not Paul, but rather his son Robert. I am very sad to write here that my dad passed away on Saturday...