I

t is not my purpose here to "rehash" well known subjects (as one would in a textbook). Rather, if I have nothing new to report on a subject, I prefer to say nothing at all, assuming that the reader is sufficiently familiar with it.

Such is often the case with relativity. The main tenets of which have been raked over ad nauseum. Therefore, I will briefly mull over a few things which I have not seen elsewhere and which I find interesting. We will not be overthrowing relativity theory which is by my accounts (and others) on about as solid ground as exists in physics.

[ Actually it is solid in a way reminiscent of the east caisson of the Brooklyn bridge. That rests on sand rather than bedrock because of nitrogen narcosis problems during construction. Similarly, one would like relativity to rest on firm bedrock logic rather than the 'sand' of the Michelson/Morley "experiment" but ... ]

Firstly:
If two physically disconnected objects (A,B) simultaneously accelerate to near light velocity [relative to an observer C equidistant from both], will the distance AB as measured by C remain the same or will it appear shortened in the direction of motion? Assume here that A and B are very distant from C.
Ans:
The distance remains the same. Even though the objects themselves (A,B) appear to shrink in the direction of motion.

The relevant fact here that is sometimes forgotten is that relativity is a physical theory and not a logical theory (a fine distinction which does not bear up under infinite scrutiny). Thus, the "electrodynamics of moving bodies" is about bodies whose parts are connected by electromagnetic bonds which are affected by velocity. Galilean relativity is a "logical" theory which doesn't pan out at high velocity but would if there were no "speed limit".

If, on the other hand, C moves and AB remains at rest, the distance AB as measured by C is altered as a function of apparent velocity.

Anyway that's the present understanding.

Of course, I don't buy into that either or I wouldn't bother to write about the subject.

What really happens at the visual level is a quick streak of light and nothing else. This is because no integrated object of ponderable size (read here electrodynamics of moving bodies) will ever be accelerated to such high velocities even by natural processes. So the most we could ever see will be something on the size order of a bottle rocket trucking along at near c. And such an object crossing our field of view at say, the distance of Saturn isn't going to be seen very well by any forseeable telescope. And if it streaks past us at 1 mile distance, we won't see anything either because no geometric relativistic effect can be seen 'head on' and the time the object spends near right angles to the observer will be too short to collect any meaningful information. So expect a blast of gamma rays, a streak of light and ... that's it ... no license plate number ... nada.

And,
If the aforementioned 'bottle rocket' was detected somehow say, 10 light years distant, coming at us at near light velocity, how much time do you think you would have to observe it?

Would you have time to:

Blink?

Answer: Blink.
Since it's coming at near light velocity, it is right behind any light you might presently see. Depending on the distance and the percentage of light velocity, you've probably got just a few seconds and that sucker will blow past. There is no upper limit to the apparent velocity of an object approaching an observer. However, there is a limit to an objects' apparent velocity receeding from the viewer. It is 1/2 c. So the bottle rocket will slow as it passes (apparently) from a zillion c to 1/2c in a blink going from gamma ray blast to infrared as it does so.

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And:
As I said, relativity is a physical rather than a logical theory. So there's this little problem with what two observers see when they pass each other at relativistic velocity.

Problem:
If A passes B at near light velocity (as dogma states), A sees B as slowed down and shortened while B sees the same thing, i.e. B sees A as being slowed down and shortened.

This matter is misunderstood.

The above statement is not logically consistent with the rest of relativity theory (forget about the visual appearance).

In fact, every object has a history of acceleration. And to be consistent with the infamous "twin paradox" (infamous for being rehashed more than any other physics idea), it must be that three possibilities exist.

• A sees B slow and short while B sees A fast and long.
• B sees A slow and short while A sees B fast and long.
• A and B see each other equally in the aforementioned dogmatic fashion.

I'll explore this more thoroughly in the other section. (Twin Paradox)

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Lastly:
I wish to add a minor principle to relativity theory. It's supposed to bridge the gap between physics and information theory. It goes like this.

The resolving power of a telescope is independent of its state of motion.

Its meaning is that we can't accelerate away from a star, point a telescope at it and, using the redshift phenomena, gleen more information about the star than we would have got if we had remained stationary. Nor should we obtain less. Same, same all same from forward direction as well. If this rule is correct, we should be able to predict some physical effects.

We can't use the blue shift to obtain more info about a star in that direction. So, since blue has greater resolution than red it must be that stars to the front of a speedy observer would appear to "jump away" from the observer as he accelerates so as to make the star subtend a smaller angle. And the stars to the rear must "come closer" to subtend a larger angle.

In fact then, the appearance of the universe to an accelerated observer is sort of "egg-shaped" darkening in the back with the observer at the rear "egg-focus", getting brighter to the forward section eventually just a point of light there.

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