Recent content by Dale

Yes, these questions are physical. But now you are asking things about coincidental things like the amount of mass in the dust cloud that formed the earth. As far as I know the only “fundamental” ratio winds up being the fine structure constant.

The vacuum permittivity doesn’t even exist in some systems of units.

That is at least a more interesting question. But then the question is less about physics than about engineering (what engineering considerations limit our maximum speed) and biology (what biological effects limit our lifespan). In my answer I tried to refocus on what actually makes ##c##...

And some unit systems don’t even have ##\epsilon_0## or ##\mu_0##.

Interesting. That data doesn’t seem particularly dire to me. From the paper "We find that a majority of faculty respondents report some experience teaching computation to undergraduate students and that a majority of departments have a simple majority of faculty reporting having such...

There are also Killing vectors that represent rigid rotations. And Born rigid accelerations too.

I don’t have access to the full article. In the abstract the authors claim “Computing is central to the enterprise of physics but few undergraduate physics courses include it in their curricula”. Do they provide any evidence to support that claim? I remember doing a double pendulum numerical...

Note that the main distinction between this post and the previous thread is the recent Nature Physics article. Please focus on discussing that. If we start rehashing the old thread then we will close this one as it would be redundant.

Yes, for example in a battery. The E field points from the positive terminal to the negative terminal, and the current goes from the negative terminal to the positive terminal. So ##\vec J \cdot \vec E## is negative and the electromagnetic field is gaining energy from the battery.

That is correct. The GPS defines coordinates (that is its purpose), so it accounts for time dilation with respect to those coordinates.

As others have mentioned, you have to decide what “real” means for your question to have meaning. The term “real” in this context is not a scientific term, it is philosophical and in the philosophical literature there is (of course) some debate. I prefer not to make a statement about whether...

Yes, I misunderstood that. The paper doesn’t describe the metric I thought it did. It has the same limitations as the Viadya metric. This is an opinion I don’t share. Lots of proofs of impossibility have some assumptions that are known to be violated and yet are not pointless, IMO. The 2nd law...

I am fine with that criticism. IMO, that goes along with the click-bait style of the title, which I don’t like. To me, that is not a substantive criticism, just a style choice I don’t prefer. I actually have a different criticism now. I had misunderstood their figure 3. It seems to me that...

Not any Penrose diagram specifies a metric that satisfies the energy conditions considered in this paper. If the metric for the standard Penrose diagram were written down and shown to satisfy the energy conditions then indeed there would be a contradiction between this paper and the literature...

In that context I like the fact that you asked to compare the various interpretations in terms of experimental evidence. That is a good approach. All of these interpretations are equally compatible with the evidence. The distinction between them and the desire to choose one over the others...