(Relativity again) what would i observe if...?

Question

... i stand right next to a traffic light which we define as point B
and a car is approaching from a distant point A

we EXCLUDE mass and momentum
we define that the car accelerates and brakes IMMEDIATLY
we have PRECISE measuring equipment faster than the eye

we define this to be a TESTBED-situation and not reality, cause i'm fully aware that this can't happen for a couple of reasons.

but WHAT would I observe if....

The car suddenly appears in A
a second later accelerates
travels
stops at B
and disappears again one second later.

what do I observe with the speed of the car being:
1. 100 mph
2. 1/2 the speed of light
3. the speed of light (this is tricky i guess)
4. twice the speed of light (and this is what i really die to know)

hey and folks be so kind and don't explain to me the basics of relativity .. its nothing new to me ...
sooo what do i observe especially in 3 + 4 ?
oh and it's not a FORD !!

@James: repeat: its NOT a FORD

Answer 1

You got lucky, I just did a reply about the effect of speed on time, so I am just going to paste that here, then add a few comments.

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First, I am going to assume that you have already accelerated to light speed (c), so the time for acceleration can be disregarded.

(And, of course I am also fogeting for the moment that traveling at c is impossible.)

Let’s go back to 1887 and the Michelson-Morley experiment. If you are unfamiliar with it, then here is a brief explination.

The Michelson-Morley experiment was intended to show Earth’s absolute motion through the ether. It did this by using a device that would split a light beam, shoot half off at 90◦ and then reflect it back. By measuring the time it took for the beam to travel they could determine if the device was moving because if the device was moving perpendicular to the beam, it would have a longer distance to travel (I could add a lot here, but trust me, this is basicly it. If you want more information do a search for Michelson-Morley experiment).

They took their measurements over a year while the Earth orbited the sun, and guess what. No difference was found! The experiment was a failure.

Why did it fail? Every one knew that the Earth moved and the experiment should have worked.

Everyone jumped on the bandwagon of coming up with different theories on why the experiment failed. Theories bounce back and forth like the beam of light, among them were:

1.)The experiment can be dismissed. Perhaps something was wrong with the equipment or the procedure or the reasoning behind it. Lord Kelvin and Oliver Lodge took that point of view.

However, this point of view is not tenable. Since 1887, numerous physicists have repeated the experiment, in 1960, masers were used for this purpose and an accuracy of one part in a trillion was achieved. But, always, the failure was repeated.

2.)Well, the experiment is valid and there is no ether wind for the following reasons.

a)The Earth is not moving. It is the center of the universe and everything revolves around it.

Let’s get real, ok. This would throw everything we ever learned about astronomy out the window.

b)The Earth does move, but in doing so it drags the neighboring ether with it so that it seems motionless compared with the ether at the earths surface.

British physicist George Stokes suggested this, but, this implies that there is friction between the Earth and the ether, and this would raise the question as to why the motions of heavenly bodies weren’t slowing down due to “ether drag”. Stokes’ notion died a quick and painless death.

c)The Irish physicist George FitzGerald suggested that all object (and therefore all measuring apparatus) grew shorter in the direction of motion in accordance to a formula which was easily derived.

The FitzGerald contraction (derived from the Michelson-Morley experiment) was one of the formulas that Albert Whatzname used in formulating his general theory of relativity.

d)The Austrian physicist Ernst Mach went right for the theart of the matter. He said there was no ether wind because there was no ether. What could be simpler?

This still doesn’t explain how light could cross a vacuum. (I could say more about Mach, but I have very little good to say about a man who believed that atoms were a convenient fiction.)

Lets go back an look at FitzGerald. What is easily derived for him is actually a bit complicated for most of us, and I am not going to show it all (I did once and bored three people to death and drove 4 to insanity), but the formula he came up with is:

L’ = L / sqr(1-v²/c²) (sqr means square root)

Old Albert Whatizname showed that you could replace time with length and the formula would still hold and be true (no one has been able to disprove it yet), so that the faster you go, the slower time would pass (I am not going to go into the effect of gravitational fields and such, but it has been demonstrated experimently that the time dilation works).

So we can subsuite T for L and we get:

T’ = T / sqr(1-v²/c²) as you can see if v=c than (1-v²/c²) = 0 and sqr(0) = 0 so we have T'=T/0 or. . .

Hold on a second . . . T/0. You can't do that!

That's right people, if you travel at c (not 9.99999999999999...% of c) time has no meaning.

It is not zero as most assume, it does not go backwards as others have assumed, it becomes totally meaningless!

So, I can't tell you how long your trip would take! But I can tell you that, once again, traveling at the speed of light is impossible.

Looks like forgeting it for the moment does not work.

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Ok, at 100 mph, the effects are not even noticable, even at .5c the effect can be ignored, and I have just shown that travel at c makes time go crazy.

Now you are taking about 2c?

Well at 2c (1-v²/c²) becomes a negetive number and when you go to take the square root of that, you get an imaginary number.

The same thing happens with length and mass.

What that would be like, I have no idea, perhaps you should bring this to a philosophy section.

Answer 2

Since the light travels at the same speed in any case, the only changes you would detect is a color shift, to blue if approaching, red of going away.

In the first case the color shift would happen but it would be smaller than background variability. The second case you would see a distinct shift. The third and fourth case could not happen in normal space time, and thus have no answer. This would also be the case for sudden disappearances.

At some tiny amount under the speed of light the wave length would approach ether zero, or infinite, but it would still travel at the speed of light,


3+4 is of course 7

Answer 3

1.100 mph - nothing unusual
2.1/2 of the speed of light - still nothing unusual(except time getting a bit slow only for car)
3.the speed of light - there will b something really unusual.time is ''almost'' stopped for car.and u will see more than one car because before light will reach u r eyes car will b ahead of its original place u'll see another car and on and on....
4.twice the speed of life - time has stopped for the car but u see can't see the car it will b literally disappeared because car won't reflect light.
( i don't think i m right!!!!!!!)

Answer 4

If the distain from A to B is short , the car will be broken.

Answer 5

THAT CANT BE DETERMINED, GIVEN THE FACT THAT YOU DONT HAVE THE EXACT MEASURE OF POINT A AND POINT B.

Answer 6

Ahh yeah, didn't get much for xmas I guess...