swansont

It’s like calling a cotton short-sleeve shirt a cooling shirt that you should wear when a wool sweater would make you too hot. Marketing. But as J. C. notes, some people like the weight of a blanket. IMO it’s not any more of a scam than other advertising language is.

Not if the theory doesn’t match experiment. Those models go into the trash bin. The size can’t depend on the method of measurement. And if the method only works for some very contrived situation, it’s not particularly useful The time isn’t the issue - it’s what we knew then vs what we knew later. I take the title of the paper to mean “here’s an interesting peculiarity about electrodynamics that turns out to have application in a more general sense” IOW, even though it was first noticed in electrodynamics, it’s not about electrodynamics.

Sounds like it’s a poor insulator. A blanket that doesn’t trap heat well, so you can use it when it’s not cold

Wait - the coordinates contract but the meter stick doesn’t? Then the coordinates are useless, since they don’t tell you where things are. The transform doesn’t actually work. It’s a mathematical exercise, meaningless for physics. If the definition of length doesn’t tell you the length, it’s pretty useless. Different measurement methods might have varying levels of precision, but if they don’t arrive at the same result, you discard the one that’s flawed. But you aren’t adjusting the definition, you’re introducing a contradiction. When we redefined the second to be based on the Cs hyperfine transition, it didn’t change the length of the second. We don’t get wildly different answers for a year based on the orbit (gravity) or counting seconds.

For a SEM, you bounce a focused beam of electrons off of the target. They hit a screen that shows the image, like a CRT TV.

The force of gravity is not infinite. The range of gravity is infinite, but the force drops off as 1/r^2

SR does not claim to work under that condition. But I must apologize; I was recalling a claim about the speed of sound being invariant but it was in another thread, by another poster. Are you really claiming that a meter stick will have its length contracted to 80 cm if measured in the wind frame?

Indeed. The wave function isn’t physical, and we do not measure it.

If the quantity has no physical significance, how is it a measurement?

Since we do not have the ability to place a sensor outside of our galaxy, no. But we can solve for it, since we know what our motion is and have measured the relative velocity of Andromeda.

IOW your equation doesn’t agree with experiment, as I said. And the frame matters.

A sound source is on a plane traveling 300 m/s. The sound travels 343 m/s inside the plane. An observer on the ground will measure the sound traveling at 643 m/s, or -43 m/s, depending on the direction the sound is traveling.

Whether an equation works depends on agreement with experiment. The equation doesn’t work in a moving coordinate system because it doesn’t agree with experiment. Sound acquires the speed of the source if the source and medium are moving together. You can transform the equation, because that’s math, but an equation that assumes an invariant speed of propagation is wrong.

Diffraction is an independently confirmable model. Most of modern physics is not based on direct measurement. That’s hard to do when things are not visible to the naked eye, even aided. We measure what we can.

They don’t measure the shape of electrons.

Fired for giving plausible-sounding but false information? The deuce, you say.

No, it’s not observable and not measurable.

Is it? Under what conditions do you have phase velocity ≠ group velocity? There are observable quantities whose product is not physically meaningful.

Something like when you have two possible answers for a square root. If one isn’t physical, you ignore it.

Not being an observable is distinct from something that isn’t directly observable. And observable means it can be measured, or the resulting effect can be measured. So virtual photons can be confirmed because the model makes testable predictions. Dark matter in inferred because of its gravitational effects, which can be measured. At the end of the day, agreement with experiment is what matters. What are the measurable effects of phase velocity?

Do you know what a derivative is?

Since the blue shift of Andromeda can be directly measured, this question makes little sense. See e.g. http://www.astrosurf.com/buil/redshift/demo.htm I’m sure papers have been published with other measurements If you want to know about significant digits, all you have to do is ask.

If there’s one reservoir there are likely more, seeing as people hadn’t been looking, and the main issue is whether it’s cost-effective to retrieve it. How much there is is important in that context, and not in relation to how much is used. It’s not like hydrogen in general is a non-renewable resource.

Goo goo g’joob But the walrus was Paul (citation: Glass Onion, The White Album)

Does he have an onion tied to his belt, (which was the style at the time in some places)?