Re: Photon, Momentum, Mass

"John Kennaugh" <JKNG@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:Q59C0ZLPYkKGFwyZ@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
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.

That's what I said

Whether that law is that the speed measured for light is c

Fair enough .. It does assume (or at least derive) that one of the laws of
phyiscs is that the speed of light is a constant c

That has been observed experimentally

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.

Counter intuitive, and difficult to imagine when we have such a deeply
ingrained model of 3D space in our minds .. but not necessarily absurd

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?

The light moves at c in the FoR of the source, and c at the FoR of the
observer. It is never observed as travelling at any other speed

That other things are moving with different velocities (including the
source) is not relevant. Light always travels at c from ANY inertial FoR

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

No .. it does not .. the speed is simply always c

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."

What physicist call mass is the rest mass (invariant mass). That mass does
not change with velocity.

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.

Obviously .. you've made up your mind to think it absurd and anything that
makes it less absurd is rejected by you.

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.

How does an electron store its charge. How dose a neutron store its mass.
I don't see why you're asking this or what difference it makes.

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!

Yes .. momentum reduces to mv at lower velocities .. reletavistic momentum
is defined differently

Again.. it appaears you have a lot of knowledge about the history of it, and
are good at picking out all the things that seem absurd to you, and ignore
the important things. Next thing you know you might be saying things
actually get crushed by distance contraction, when their proper length is
unchanged.


.

Relevant Pages

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