Re: Photon, Momentum, Mass

Jeckyl wrote:
On Apr 20, 4:21 am, John Kennaugh
<J...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Y wrote:
You are studying the wrong subject and are posting to the wrong
newsgroup if you want anything to appear sane. Relativity is based upon
the assumption that the speed of light is constant w.r.t the observer
observing it no matter how far away the source is nor how long ago the
light set out.

That is one of the results you get from the principle of relativity, that
say the same laws of physics apply in all inertial frames of referenec (ie
phyics don't change just because you are moving relative to someone else).
That is a VERY sensible principle. Do you instead claim we should NOT have
that premise, and that the laws of physics should change when you are moving
relative to something else (or vice versa) ?

The principle of relativity does not result in the above.

What the PoR says is that you will always get the same law in any inertial FoR. Whether that law is that the speed measured for light is c even if the source is moving or whether it is that the speed is always c+v from a source receding at v.

In common English usage whether the speed of light is c w.r.t the observer (SR) or c in respect of the source (BaTh).

In fact BaTh is more comfortable with the PoR than SR. Einstein himself said the second postulate (which is what distinguishes SR from BaTh) was "apparently irreconcilable" with the PoR and only managed to reconcile it by ditching 3 former axioms of physics.

The PoR goes was re-started by Newton but it goes further back than that to Galileo I think. It was 'ruled out by the aether theory which again dates back to Newton (although he rejected it). If there is an aether it was in theory possible to devise an experiment which would give different results in different FoR because of the FoR's speed w.r.t the aether. The MMX was just such an experiment and such was the status of Maxwell that it was fully expected that it would give a non null result which is why the null result was so devastating. The MMX was only one of several experiments which produced the same conclusion. Thus the reason the PoR had been set aside was shown experimentally to be invalid so the PoR could be reinstated.

This is clearly absurd.

Some of the restulst are counter-intuititive to those who have seen the
restulst only, and not understand how they are derived.

I did not say the maths was absurd. Once you accept the second postulate the maths follow and I do understand how they are derived. The absurdity comes in trying to produce a physical model to go with the maths. Both the provenance of the second postulate and the physical consequences are
absurd.

Einstein assumed that despite the MMX and despite the fact that light is particulate that Maxwell's aether theory was correct. It predicted that the only time the MMX should give a null result is if the apparatus is stationary w.r.t the aether. Effectively Einstein took that at face value i.e. whatever it means physically, in effect the observer always finds himself stationary w.r.t the aether. That is what the second postulate is describing, what an observer stationary w.r.t the aether would experience. His only attempt to provide a physical model was in a lecture in 1920 where he was deliberately vague but was hinting at an aether which every observer is naturally stationary w.r.t. - an aether "without the immobility of Lorentz's". The point is that Einstein needed some sort of aether because it is the aether which controls the speed of light and prevents the source from affecting it. OTOH the conventional aether has associated with it a unique FoR so that won't do. It was the unique FoR associated with the aether, not the aether itself which Einstein wanted to get rid of. Most would conclude that you can't have one without the other.

The fact that light had been found to be particulate should have meant that Maxwell was dead in the water. A useful approximation which engineers could use but not a definitive mathematical model of nature. Particles don't need an aether and if there is no aether the fact that the MMX et al failed to find one is hardly surprising. The question then becomes "if the speed of light is not constant w.r.t the aether then what does control it? The obvious answer - the only sensible answer is that the physical process ejecting the photons sets them on their way at c.

SR of course requires that the light in an observer FoR separates from the source at c+v so as to be c w.r.t that observer. If there is no aether then how can anything have an effect on what speed light separates from the source at, other than the source?

What you have in SR is a hotch potch. SR is a non-aether, aether theory. The "no aether doctrine" has been accepted by physics but as you see from above the logical outcome of assuming 'no aether' is source dependency. SR is the result of an unwillingness to ditch old discredited theory clinging as it does to Maxwell and aether based source independence when the evidence was pointing the other way. The only physical model consistent with SR maths is still Lorentz's aether theory.

The acceptance of the "no aether doctrine" means not only that LET is rejected but that it is impossible ever to produce a physical theory to go with SR maths because anyone inclined to try is denied the existence of anything physical he could use as part of a physical process.

Essentially the denial of an aether means that the source must control the speed of light as there is nothing to prevent it.

According to relativity anything with mass increases its mass as its
speed increases

No .. relativity says mass is invariant

I think that physicists have redefined mass several times since Einstein. He writes "If a body takes up an amount of energy E then its inertial mass increases by E/cc."


until it becomes infinite when it reaches the speed of
light c. Therefore if you accept relativity a photon cannot have any
mass because if it had it would have to be infinite.

No .. relativity doesn't say that, it says the energy of the photon wouldbe
infinite. The mass would remain at whatever the mass is, because mass does
not chagne with velocity.

If you say so. I don't really care.
I would be more interested to know how a photon stores its energy in other words what makes a low energy photon different to a higher energy
photon.


OTOH a photon has
energy and energy and mass are equivalent.

The energyof a photon comes from momentum,

And momentum is defined as mv is it not or has that also been redefined!

not mass. . it is not only energy
and mass that are related in special relativity

The result is that they
invent a different sort of mass which isn't really mass but behaves like
mass when they need it to .........

You may be talking about the concept of relativistic mass which indeed is
not mass, and is not really used as it is not a useful concept.

E = mc^2 means there is an equivalence between mass and energy, not
that they are the same thing.

That is the formula for rest energy .. the energy in an object when it is at
rest. That energy comes from the rest mass.


--
John Kennaugh

.

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