Speed of Light always remains constant ? think again.

[Gokul43201]

Since this (what follows) is the claim you are making, let's, for the sake of science and sanity, address it.

Its clear here that R2 covered the same distance that R1 did after firing the lasers

Yes, this follows your statement that R2 "starts flying with R1". However, you claim that speeds and positions can be matched after some period of positive acceleration. This is not possible.

Here's what you said :

Few hours after firing the laser, R2 starts accelerating towards D and quickly showing its raw power, matches the speed and starts flying with R1.

I assume that all speeds spoken of are measured by an observer at rest in the rest frame of P1, P2 and D. Even simple, non-relativistic kinematics will show you that if R2's speed is monotonically increasing, and R1's is constant, then if R2 covers the same distance as R1 in less (or equal) time than R1, then R2's final velocity will greatly exceed R1's. The only way they can match positions and speeds is if R2 slows down as it approaches R1.

Does this new knowledge change anything ? If not, let's proceed.

yet laser fired by R2 is not going to over take laser fired by R1

There are several points to address here :

This is the first statement you are making about things necessarily traveling at or near the speed of light, so you must first tell us what framework you are working under. Clearly, you are not basing this statement on the framework of SR (or are you ?). Are you using the "Galilean framework", where the speed of the light beam at P1 is v+c ? Or are you using some other system of thought for understanding the kinematics of fast moving objects ?

Opening this clause with 'yet' means that what follows is related to the preceding clause (talking about "raw power" and "matching speeds"). So, this indicates that you expect the motions of the rockets, subsequent to firing the lasers to affect the possibility of one beam overtaking the other. The only way this might be true, in any system of thought, is if the kinematics of the beams (with respect to an observer at rest in this frame) is coupled forever to the kinematics of the source that emitted it - some kind of "entanglement" is suggested. Alternatively, you might be suggesting that the kinematics of the beams is being described with respect to one of the two rockets, but there is no such mention in the clause. So, this clause merely leaves the reader saying "uhhh?"

Nevertheless, let's accept it and analyze what it might be saying. You then use the word(s) "over take" (by which I'll assume you mean the single word 'overtake'), which is not well-defined. Does A have to lag behind B in order to 'overtake' B ? If A and B are traveling side-by-side and A speeds up, does it 'overtake' B ? Either way, you are claiming that the beam from P2 does not get ahead of the beam from P1 (with respect to the observer at rest ?). There is no suggested reason why this must be true, given that we have no idea what system of science is being used in this discussion. In both Galilean and SR frameworks, this statement will indeed be true, and in fact, in both frameworks it would be true independent of the subsequent dynamics of the rockets. For now let's accept it as true, and proceed.

and hence comapred to R1 speed of light for R2 was less when it was accelerating near R1.

Now where did this come from ? Starting off with "and hence", indicates that what follows must be derived from what preceded. Where is the logical connect ? If it is just our failing to connect the dots, do show us how they are connected.

This is like saying : "Today is a warm day, and hence Chopin never played piano. Prove me wrong."

Anyway, there are other issues to sort out with this clause too.

You talk of the "speed of light for R2". So, you seem to suggest that speeds are observer dependent (though you haven't mention how an observer measures the speed of light). So why, until this point, have to never mentioned the frame in which various speeds that you talk of are measured ? Let's ignore that too for now.

You are saying that, at some point of time, R2 was "accelerating near R1". I assume that by "accelerating" you are referring to a positive acceleration with respect to the direction vector pointing from P2 to D (as measured by the observer at rest). As I explained earlier, monotonic acceleration of R2 can not result in the final specified condition of matching speeds and positions. The only way R2 can be positively accelerating beside R1 with the same instantaneous velocity as R1, is if it had already overtaken R1, then slowed down to a speed below R1's (still maintaining a lead over R1) and then subsequently sped up again, allowing R1 to catch up with it (rather than the other way round). But there is absolutely no mention that this the the second time the rockets will be side by side, or that it is R1 that comes up to R2 from behind. In fact, the opposite is suggested.

 

[wisp]

... let's, for the sake of science and sanity, address it.
...

A simplified approach.

Since the light fired from both rockets travels at the same speed c (the motion of the light's source doesn't affect the speed of light - proven fact), we could simplify matters by letting point D emit light towards R1 and R2, and look at it in terms of Doppler shift.

The stationary rocket will record the light traveling towards it as having an observed frequency the same as the source, Fobs = Fsource.

When the rocket moves relative to the source (D) at speed V. It will record a frequency of Fobs= Fsource*squareroot[(1+V/c)/(1-V/c)]

The bottom line is: both SR and an alternative approach using c+V will give the same answers for the Doppler frequencey shift. And so you can't use this to show relativity is wrong, which is frustrating, but that's the way it is.

 

[c_helm@yahoo.com]

Take 3 points P1, P2 and D

Point D is at a fantastic distance from P1 P2.

Point P1 is very near to P2 and both are at equal distance from D.

A Rocket R2 is waiting at P2

Rocket R1 is approaching at tremendous velocity at point P1 and towards D.

At the instance when the rocket R1 reaches P1, both the rockets simultaneously fire a powerful laser beam ( may be a few meters in length ) towards D.

Few hours after firing the laser, R2 starts accelerating towards D and quickly showing its raw power, matches the speed and starts flying with R1.

Now, will the speed of already fired lasers that haven't yet reached D with respect to R2 decrease ? now that it has come closer to the R1 hours after firing the laser, and while both the lasers together are approaching D.

I am a rookie at best, so please forgive me if this question seems simplistic or its answer painfully obvious. But...

If R1 is in motion (at a tremendous velocity) as it approaches P1, and R2 is waiting, therefore at rest, at P2: would the relative gravity have more effect on the light leaving R2? Is it still accepted that light "bends" if enough gravitational force is exerted? So, if there is enough gravity to pull at R2's laser, but R1's momentum is enough to overcome it, will R2's beam actually have a bit farther to travel since it will be approaching D as a curve-ball? If so, then the speed is constant between the two, but one must travel farther, arriving later.

Am I way off base? Be gentle.

 

[EnumaElish]

Not even a rookie, a beginner at best

Anomalous,

I may be totally off the wall here. But bear with me. (I will especially appreciate any comments pointing to any errors in my posting.)

R2 has been speeding up to catch up with R1, so its crew have been measuring time at a slower pace. At the point where R2 catches up with R1, its clock no longer matches with R1's. R2's clock has been slowed down relative to R1's clock.

Had that not happened, R1 and R2 would have measured different speeds of light. But because it happens, they do not.

Put differently, since both crews take a measurement and observe the same speed of light, their notions of time must be different.

I hope this is correct and useful.

Take 3 points P1, P2 and D

Point D is at a fantastic distance from P1 P2.

Point P1 is very near to P2 and both are at equal distance from D.

A Rocket R2 is waiting at P2

Rocket R1 is approaching at tremendous velocity at point P1 and towards D.

At the instance when the rocket R1 reaches P1, both the rockets simultaneously fire a powerful laser beam ( may be a few meters in length ) towards D.

Few hours after firing the laser, R2 starts accelerating towards D and quickly showing its raw power, matches the speed and starts flying with R1.

Now, will the speed of already fired lasers that haven't yet reached D with respect to R2 decrease ? now that it has come closer to the R1 hours after firing the laser, and while both the lasers together are approaching D.

 

[clj4]

The bottom line is: both SR and an alternative approach using c+V will give the same answers for the Doppler frequencey shift. And so you can't use this to show relativity is wrong, which is frustrating, but that's the way it is.

This is patently wrong. SR and the ballistic ('c+v') theory give different answers for the Ives-Stilwell experiment. SR gives the correct result (confirmed by experiment), the 'c+v' gives the wrong one.

 

[LostInSpaceTime]

What I am asking is that , without knowledge of all that super science, What seems so obvious to me seems so wrong to others here.

In my thought experiment it seems impossible that speed of light should remain at C for R2 as it covered vast distance after firing the lasers, hence while it was in acceleration its impossible that speed of light of the fired lasers was C at that time, Thats all I am saying.

Not sure but I think you might be confused by the whole if your going 60km/hr and you throw a ball out the car window in the same direction at 15 km/hr the the balls total speed is 75km/h scenario.

Basically (from what i understand) light doesn't work that way. If you shoot a light beam out the window as you are going almost the speed of light the light beam still only travels c. I know this is an old thread but it would appear that's the source of confusion. (Either that or I've totally missed the point to his question)

 

[pervect]

This thread is over two years old. Let's let it rest in peace, and if you have questions, start a new thread, hopefully one of higher quality.