# Toffo

Senior Members

62

1. ## Angular motion in special relativity?

Yes they do. If a photon collides with the blocking object, it collides according to everyone. Collisions are absolute.
2. ## Time dilation puzzle

Mouse thinks about the equivalence principle: "If I am sitting on a chair in a gravity field, or in an accelerating rocket, and the cat has just fallen off his chair next to me, then me and the cat are experiencing the same gravitational time dilation. Or, to put it more briefly: me and the cat are near each other, therefore I can ignore my own acceleration."
3. ## Time dilation puzzle

Mouse says: "Cat travels away at speed v, then cat travels back at speed v, so cat ages at half the normal rate (because v is such that time dilation factor is 1/2), my own aging rate is the normal rate."
4. ## Dilation and inertial frames

Twin A says: "Twin B travels away and ages slowly, then he travels back and ages slowly, all according to Lorentz equation." Before reading further the reader may perhaps want to to try to think what twin B might say. Twin B says: "Twin A travels away and ages slowly, then he travels back and ages slowly, all according to Lorentz equation. In the middle a GR thing happens, which thing is fast aging of A" Twin A's comment to the above: "I don't remember any fast aging of myself."
5. ## Angular motion in special relativity?

More important is that to the paper the apparently moving light source apparently sprinkles the the light all around. (but not really) A light source that really moves around, really sprinkles the light all around, which increases the entropy of the light. All observers agree about entropy.
6. ## Angular motion in special relativity?

Yes. Exactly. And to the quoted text below I say: No. It can not be that way. All observers must agree about the percentage. (Maybe some day I'll learn to use this quote system correctly )
7. ## Where does energy for gravity come from?

Energy for falling comes from potential energy. Potential energy's maximum energy is zero. When energy is taken from potential energy, potential energy becomes negative. There's no limit how negative the potential energy can become, so infinite amount of energy can be taken from potential energy.
8. ## Gravitational redshift and length contraction factors

I see. Everybody is confused here. People are trying to make the coordinate velocity of light to be c. Coordinate velocity of a light beam may be anything from zero to infinity. (Distant meter sticks are not necesarily 1 m. Distant light beams are not necessarily 300000 km/s.) (Maybe in schwarzschild coorditates light always has coordinate velocity c, but I don't like schwarzschild coordinates, probably the aforementioned confusion is schwarzschild coordinates' fault)
9. ## Angular motion in special relativity?

Yeah it works roughly as I said. A static piece of paper in front of a light source blocks 10% of the light. Then we move the same piece of paper around at speed 0.86 c. Now the paper blocks 5 % of the light. Do you disagree?
10. ## Angular motion in special relativity?

When viewed from the Sun, the Earth looks kind of narrow, because of the orbital motion. Some sunrays miss the Earth, because of the narrowness. Everybody agrees that motion causes the Sun facing side of the Earth to receive less sunlight. And everybody agrees that the Earth moves around the Sun, while the Sun does not move around the Earth.
11. ## Gravitational redshift and length contraction factors

By the way, there is no good reason why meter sticks would change in gravity fields. If relativity is involved and length change is involved, meter sticks can very well be uninvolved, although meter sticks are involved in relativistic length change of meter sticks.
12. ## Gravitational redshift and length contraction factors

Meter sticks and photons are quite different. Photons expand when climbing up from a gravity well. Meter sticks very rarely climb up from a gravity well. Even the rare sticks that climb up from a gravity well don't expand, except maybe in some rare cases, where the climbing energy comes from such a part of the stick that expansion is the result of the energy loss .
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