Recent content by Nugatory

There's not much point in proposing a greek letter for us in describing multiverses when the multiverse notion is an idle speculation that is no part of any serious physical theory and cannot even in principle have any observational consequences. This threaad is closed, and anyone coming across...

Most relativity "paradoxes" are better described as "apparent contradiction resulting from a hidden bogus assumption, often used as a pedagogical device to help students recognize bogus assumptions". By that definition, yes, it is a paradox. But.... This assumes that when the train augurs in...

Sure, if you assume the simuulation hypothesis then anything is possible; the master software developer just has to hack together a few lines of code to make something that is impossible under the laws of physics possible. All science is meaningless, because any experimental result can be...

With tongue somewhat in cheek, I've said that I used my undergraduate physics degree the way that a male peacock uses its tail feathers: The peacock is displaying the feathers as a proxy for reproductive fitness and I was displaying the degree as a proxy for knowing how to apply math to hard...

Enough so that we have a live report against them.... A flood of low quality low information posts from an account started 18 hours ago.

It is not impossible that more years (decades?) of AI development will lead to conscious physical systems In which the underlying physics is well understood. We may be perplexed by the emergent behavior of a system of, say, ##10^{15}## transistors, but we would not doubt that we understand the...

If it is at rest in the center of mass frame and we have arranged for a fully inelastic collision to happen inside it?

This is tricky even without introducing the complexities of an evaporating black hole. "Crosses the horizon at a finite proper time ##\tau_1##" doesn't make sense unless and until we specify the point on the infaller's worldline where the proper time has been arbitrarily considered to be zero...

This is a false dichotomy. For purposes of constructive discussion of special relativity, forty or so hours with Taylor and Wheeler’s “Spacetime Physics” will suffice, and that’s a few months of hobby/spare time not the years that you’re talking about. Taylor and Wheeler first edition is free...

The equivalence principle says that sitting in a box at rest on the surface of a gravitating body (for example, in a closed room on the surface of the rest) is indistinguishable from sitting in a box that is being accelerated in empty space - Google for "Einstein's elevator" for more. And of...

When @geordief wrote that he was still under the misunderstanding that “I think parallel transport relies on these tangent planes [that is, planes in the 3D space]” from the original post.

Does that force us to deal with clock synchronization? Start with a source of light signals and a mirror, move the mirror around until the reflected signal is back at the source in 2/299792458 seconds and we have a one-clock standard meter. I’m thinking that we need clock synchronization for a...

They aren't "on" the sphere anywhere. There is a mapping from each point on the surface of the sphere to a two-dimensional vector space specific to that point, which we call the "tangent space" at that point. But the elements of that vector space are neither vectors in the embedding...

The tangent space at a point is not a plane in the 3D embedding space (although that is a natural way of visualizing it, continuing our general tendency to think of the 2D surface of a sphere as embedded in the 3D euclidean space containing the sphere) and can be defined without reference to...

You have been victimized by pop-sci misdescriptions. The entire notion of “wave-particle duality” was abandoned as a false start almost a century ago and is not part of the modern understanding of quantum mechanics. There’s no substitute for a real textbook with its non-trivial mathematical...