J.C.MacSwell

Assuming all other things being more or less equal (diameter of jet etc.): Below the waterline the surrounding water would provide more back pressure than the air above and therefore more thrust for the same power. Because you would be effectively propelling more mass aftward (relative to the body of water or freestream) you would be imparting more momentum for the same power. (the exit velocity would actually be slower). So more of the energy would go to the craft and less to the jet. Hope this makes sense.

Below.

A stream of Beta radiation would fit that description. Would that be considered electricity? How about a stream of alpha particles? That would also be a flow of charge although obviously not electrons. If the streams above were deflected what differences would there be in the resulting Electromagnetic radiations?

Any "theoretical" upper limit on EM radiation. (seriously) Could a "Rogue Wave" single photon come and wipe us out while we are carefully scanning the heavens for threatening asteroids?

No question in my mind that in this thought experiment the clock that went further will be "younger", primarily due to the due to the SR effect. The GR effects could be symmetrical. I do wonder: What is the "BEST" experimental evidence to support this. All evidence I have seen has a major GR component chomping into any margin of error. It is impossible to get any results on SR without being exposed to some GR effects. The best we can hope for is to make them symmetrical (with respect to what though, time or distance etc.) or to factor them out based on theory. It is also impossible to make them perfectly symmetrical or you would be duplicating the same test. No comparison could be made. Apologies if any of that does not make sense.

Thank-you. I was surprised that Sevarians particle physics description of matter excluded the gluon.

But doesn't exciting an atom add rest mass to the atom, though (I think, not sure- I see it as kinetic?) not the electron? By this definition (which I now suspect is wrong but was my original thought) I would have created additional matter. Using the broadest possible definition if you had a big hollow sphere in outer space, filled with rubber balls bouncing around would their kinetic energy add to the "rest mass" of the big hollow sphere/system? I think it would be equivalent (add to it's inertia etc.) would it not? Obviously a stretch to call "that" additional matter.

I was using, "energy of rest mass" as constituting matter, but I now suspect this is incorrect. An excitation of an atom would add to it's rest mass, would it not? Any thoughts? On the same subject would the heat energy of a body add to it's rest mass? I would say yes (even though it does not add to the rest mass of the constituent atoms) but I would not think of this as matter so I am obviously unsure of where the line is drawn. I think (now) matter is supposed to have some degree of "permanence" under normal conditions, so this may be too broad a definition that I was using. (even though matter created in some accelerator experiments is far from "somewhat permanent under normal conditions"). I would like to know where the lines are drawn (and more interestingly "why")

What if you had two cats in the box, one male and one female. After, say, 10 minutes a decay device will trigger one of them dead in a way that won't effect the other. (Say it triggers a cyanide capsule to rupture in the stomach). So you have a live/dead cat and another live/dead cat. Can they interfere with each other? Assume there is enough food and water in the box/system and half the box was isolated/compartmented so the cats can't get to it because of a trap door than wasn't (quite) big enough. After a year the trap door is sealed and the isolation/compartment is saved and the remaining half is jettisoned into a black hole. When the isolation/compartment is opened could it contain any kittens?

More energy is bound (somewhat) in the atom. The rest mass of the atom has increased.(?) Does this not represent an increase in matter? Or am I getting the definition wrong? (I suspect I may be))

If a photon is absorbed by an atom bumping up an electron isn't that an increase of matter.(and therefore creation/transformation of energy into matter)

So it's Einstein's fault? Nobody blamed Newton when they fell down.

Isn't it a non-accelerating frame?