Why nothing can go faster than speed of light.

[Tim88]

 

OK.

The problem that I see with that is, first of all, that according to SR the force that is experienced by the rocket in a co-moving reference system, is just the everyday reaction force; and the transformation factor of force in that direction is 1. In other words, according to SR, if we use the reference system in which the rocket is moving very fast, the force on the rocket is NOT reduced. Your assertion is therefore in disagreement with SR.

For reference you can look up §6 of https://www.fourmilab.ch/etexts/einstein/specrel/www/

Alternatively you can "google" the same in more modern texts, I found for example http://www.sciencebits.com/Transformation-Forces-Relativity (disclaimer: I did not check the derivation there).

 

Further, as far as I know our technology has not yet reached the point of verifying the theory for rockets; but it has been done for a somewhat similar case, that of electrons.

Probably you would apply the same reasoning as you did on accelerated electrons, and claim that these cannot reach the speed of light because the "push" of the electric field on the electron becomes infinitely small at speed c. (correct?).

That reasoning has effectively been disproved by the Bertozzi demonstration experiment, which verified the added kinetic energy at high speeds by measuring the energy that was released at impact. The electron is, as measured in the lab, truly a "high energy" or "heavy" particle in agreement with the amount of added kinetic energy according to SR.

 

 

Let me reduce the rocket example to two interacting electrons, A and B, traveling one after another, B in front of A. And there is an observer measuring their equal velocity.

The interaction takes place by sending photons to each other which travel at the speed of light. The speed of the photon is independent of its source speed. Nothing strange with that, same thing with water and sound pulses.

When the pair of electrons move relative the observer, the photon from A to B will need to traverse a longer distance compared to when the electrons are at rest. When they move at the speed of light the photon from A will never reach B and therefore B cannot be accelerated further.

[..]

 

According to SR the exchange happens with fields, but that's probably not the issue here (to make sure, pleases stick to SR in this sub forum on relativity). As you write "When they move at the speed of light the photon from A will never reach B and therefore B cannot be accelerated further", it sounds as if you are making exactly the same error that I put my finger on earlier and which is in conflict with theory and measurements, as I also already tried to clarify; probably that clarification needs expansion.

 

My example of an electron that is affected by an electric field is similar to your example of an electron that is affected by the presence of another electron. If at the speed of light the interaction of the electric field never reaches the electron, then it's not pushed anymore. I suppose that you do not claim that Newton's mechanics is followed up to speed c, and then suddenly there is no more acceleration. Consequently you probably mean that the "push" is reduced the closer that the speed is to c.

And so we're back to:

 

1. The fact that the electron is still pushed with force F up to the speed of light according to SR: even with the same F according to both observers (according to both reference systems), no matter what the speed is.

 

2. We're also back to Bertozzi experiment (Bertozzi 1964). If the electron is practically not pushed further, then also practically zero further work F∆s is done on it by the electric field, because F=0. Energy conservation implies that the kinetic energy of the electron cannot increase if no further energy is given to it.

 

Instead, he demonstrated that the kinetic energy of a fast electron increases just as much as that of a slow electron. As he summarized it (emphasis mine):

 

The kinetic energy, determined by calorimetry, verifies that an electric field exerts a force on a moving electron in its direction of motion that is independent of its speed.

As an afterthought, it struck me that possibly I misunderstood you, and you think that an electron can escape from the influence of a field if it goes fast enough. However no escape from the electric field between the plates is possible as the electron passes through.

Edited April 21, 2017 by Tim88

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Discussion on Lorentz Transforms has been split

http://www.scienceforums.net/topic/105118-lorentz-transformations-split-from-why-nothing-c/