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Q & A: relativity questions

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Most recent answer: 10/18/2011
Q:
My questions are endless and I'd very much appreciate establishing a rapport with one or more top theoretical physicists, so that I'm not typing in volumes just to be ignored. Perhaps I could begin with a couple of easy ones. Supposing the technology existed for two space ships in earth orbit to both take off in opposite directions at 0.99999 (whatever) the speed of light. One second later, each is one light second from the earth, but they are both 2 light seconds from each other. (Yes? No? This reminds me of the 2 automobiles traveling towards each other at 50mph and colliding head on. Is that identical to one vehicle being stationary and the other at 100mph? One could say in the first example the kinetic energy of each vehicle is absorbed by each vehicle - as evidenced by there being no difference had there been an impenetrable wall between them. But in the 2nd case, the wall would have had to be moving at 50mph for identical results? Or how DOES one reconcile this puzzle? And in the case of the spaceships, for all the nay-sayers, how does what one mass traveling near c have ANYTHING to do with another mass traveling near c in ANY direction? And then of course, the theoretical argument that if we were in orbit and then somehow Earth was traveling away from us at near c, and we took off the other direction at near c, are we not traveling away from the earth at near 2c??? And if not, why not?? And if so then travel at 2c is possible...) But I have some much better ones. For a taste, if a photon does not experience time, then it cannot experience distance either. (Photons just now reaching us that started 13.7 billion light years ago, did not experience 13.7 billion years having elapsed. From their perspective, time=0 so then distance=0 too! So then I must conclude that to a photon, our 3-D space-time is indistinguishable from what theorists have identified as "collapsed dimensions". Well, could it be that it's merely a matter of perspective???) Ok, one more. If a photon is itself "electromagnetic", then why isn't its trajectory affected by a magnetic fiend?? Nah, two more. If "magnetism" "N" and "S" is merely spiraling electrons spinning either CW or CCW which either mesh ("attract") or oppose ("repel") then that raises a number of very intriguing questions. First, what "magic" keeps a photon spinning around a non-existent center? Second, how can a "mass-less" (wave? particle?) exert a tangible force which when multiplied by unimaginable quantities nevertheless adds up to a very impressive force? (Kind of reminds mr of zero times near-infinity, with the photon interactions being 0, he end result will still be zero!) Next, the photons themselves have to travel "faster than light" if they're traveling in spirals and it's their "forward velocity" that we accept as "c". And finally, even if there WAS something to this helical stuff, then the "force of magnetism" may not be a "new" force at all, but one or more of the other three.) I've just now gotten used to the idea of gravity stretching space. (But then why isn't distance affected too - such as your measuring tape, which works quite well on the ground, off by some measurable amount when in orbit? Can't we measure the amount space is stretching from the red shifts of the receding galaxies? And if Space is already being stretched in all directions, and then we throw earth's gravity into the mix, well, what keeps everything from becoming entangled or overlapping or something? It just seems there would be some easy way to tele-transport anywhere in the universe, and then time travel is merely the next step! Ok - I can't help it. Could it be that the "spirit" realm we read about in the Bible is merely one or maybe two of our well established 3-D space overlapping another 3-D universe ("Heaven" and "Hell"), but we share the same timeline (otherwise one could not "rebuke devils" in real time as the Lord reportedly did, nor could "spirits" pick up furniture in this world and hurl it against the far wall - at least if one believe that happens, and also if we both didn't share the same timeline then anyone who died couldn't immediately "go to" Heaven or Hell...) And IF there IS anything to this "parallel universe"... (backing up, I'm wondering if I've convinced myself that a whole new "copy" of our entire universe is (somehow) "created" every 10^-40 seconds and joined to it along this 4th spacial dimension we call "time" - and if so, how much energy would it require to do that and where would all this energy come from?) But IF our universe is capable of THAT then it seems a simple matter to multiply it all by infinity again and have endless parallel universes (which are generally branched off based upon decisions people make - "yes" creating one new parallel universe and "no" creating another - but to my way of thinking, with 5 billion people making who knows how many decisions, we're back to this 10^-40 or so resolution just to cover all the bases!) which incidentally explains (to me) how "two-dimensional time" might possibly work!! But if there was anything to this "spirit world" merely being another spacial connection, connected or intertwined and/or connected somehow, then wouldn't it be a simple matter of performing some test that would somehow make it possible for one to cross over? (I'm amazed that black holes aren't busily emptying themselves out somewhere, having connected two distant points in space together somehow. I'm even amazed that there isn't some "leaking" forward or backward thru time whenever a hydrogen bomb is exploded - not even by picoseconds, I've been informed by someone involved in the highest speed photography imaginable. Answers are very much appreciated - even if you prefer to separate these, and tackle them one at a time. Thanks in advance, C Brown
- Craig Brown (age 56)
Lafayette IN
A:
I'll tackle a few of these here, focusing on the more standard science questions.

" ....they are both 2 light seconds from each other. (Yes? No?)" Yes in our reference frame, no in either of their reference frames. The velocity addition formula is w= (v+u)/(1+uv/c2) where u is the velocity of say B in A's frame and v is the velocity of C in B's frame, and w is the velocity of C in A's frame. For the cars, that's very close to w=u+v, but once u and v start getting comparable to c, then it's a lot different. That answers several of your first batch of questions.

The parts about what a photon experiences are beyond me- the transformations of Special Relativity don't extend to those reference frames.

A photon is electromagnetic but it is not charged and has no magnetic moment. Therefore it experiences no force from electromagnetic fields, within the classical approximation. It does exert forces on charged particles or ones with magnetic moment, and vice versa.

Yes, the gravitational distortions of space are real. In fact, in a standard representation those spatial effects account for half of the bending of light as it passes near the sun.


 Maybe that will get you started.

Mike W.

p.s. Lee is in Paris, so this is temporarily posted without our usual check.

(published on 10/18/2011)

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