Re: PHOTON MASS -- A FACT. MASSLESS PARTICLES -- NOT FACT.


Vert wrote:
PD wrote:
Vert wrote:
Peter Christensen wrote:
"Vert" <avergon@xxxxxxxxxxx> skrev i en meddelelse
news:1150992050.310579.256480@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
They *believe* there are such things as massless particles and massless
photons.

It has been known for almost 100 years. It's not just a belief.

VERGON
You are all wet. I have a book by a leading expert on light. He wrote a
famous text book on the one subject.
LIGHT by Ditchburn, 1952 --- and he gives the mass of the photon.

Ah, nothing better than an old Dover book. Excellent, I'll look it up
to see what he says. Is that the most recent reference you have?


Also, Ptolemaic epicycles were known for 14 CENTURIES. That didn't
make them right.


Maybe you could try to argue why the photon should have a non-zero mass?

VERGON
I've done this throughout this thread.

For one thing it has enegy and momentum. You cannot have energy and
momentum without mass.

What on earth gives you that idea?
VERGON
E= mc^2, E = mv^2/2, E = pc, E = ( 1/sqrt[1 - v^2/c^2] - 1)mc^2.
There's m in every one of them.

Where is the mass of the photon in E=pc?
(Note the other ones you've listed are for massive particles only. Nor
is this an exhaustive list. For example, you've not listed the energy
carried by a static electric field in a volume where there are no
charged particles. Are these the only formulas for energy you've
learned?)


p = mv, p = hf/c, p = mv/sqrt(1 - v^2/c^2),
There's m in every one of them.

Where is the mass of the photon in p = hf/c?
(Note the other ones you've listed are for massive particles only. Nor
is this an exhaustive list. For example, you've not listed the momentum
carried by electromagnetic plane waves in a region far away from
charged particles; see Poynting vector. Are these the only formulas for
momentum you've learned?)


THAT'S what on earth gave me that idea. I'm surprised that you are so
ignorant I had to explain to you what every one knows.

Gee, I don't know why you project your mistaken notions to be those
that "everyone" knows. If "everyone" knows it, then I'd think you'd be
able to ask just about anyone whether they agree with it or not. If
they don't, then I'd say you'd better reconsider whether "everyone"
knows it.




I hereby offer a challenge to anyone competent to prove to me that the
photon has no mass.
So what say you?

It's known (also from experiments), that for photons E = p*c. When comparing
with the equation from relativity, that relates energy, momentum and mass,
then it can be concluded that m must be zero for photons. Only a zero value
of the mass gives the right (and experimental) result: E = p*c. This has
been verified many times, as both E and p can be measured.

PC

VERGON
Einstein gives the mass of radiation (the photon) as m = E/c^2.

No he didn't. Where on earth did you get that idea?
VERGON
You are exhibiting an abysmal ignorance. Read his second paper of 1905.

OK, I don't see it in there. You might want to be specific.




The energy of the photon is given as E = pc = h nu.

Then there is the often misinterpretation of the energy-momentum 4
vector equation.

This equation is nothing more or less than the combination of
Einstein's equations for the energy and momentum of moving
*bodies* -- "bodies" -- as in ponderous mass.

One interpretation of the equation, E^2 = (mc^2)^2 + (pc)^2 is as
follows:

"If we set the m in the right hand first term to zero, then we get E =
pc
which we know is true. This shows that the mass of the photon is zero."

WRONG.
The first term is the square of mc^2. In case one forgets, mc^2 is REST
energy -- and the m is REST mass.

Do we agree that the REST mass of the photon is zero? Of course.
A photon brought to rest (by absorption) is no longer a photon -- so
its REST mass is zero.

The *mass* as defined by physicists is the *invariant* mass. Now where
do you suppose that appears in E^2 = (mc^2)^2 + (pc)^2 ?


The second RH term is pc, the energy of a photon IN FLIGHT. The p is
momentum -- which we know the photon in flight has. So we see the 4
vector equation is not suitable for the photon as it covers two
separate conditions of the photon, at rest and in flight.

Every equation for momentum contains MASS and motion.

No it doesn't. Where on earth did you get that idea?

Therefore
E = pc states that the photon in flight has mass. p = mc,
and pc = mc c = mc^2 = E. To say that a photon has zero rest mass is
to say it is at rest (absorbed) and therefore has no motion. Thus pc
doesn't apply.

When faced with that fact, the poor souls who misinterpreted the
equation try to maintain their position by declaring a new physics
whereby there exists momentum with no mass.

The problem is, they cannot substantiate that.


The overall result is that there is no such thing as a mass-less
particle -- of any kind.

The objective universe consists only of matter (mass), the space
between matter - and the motion of matter in that space.
All else are concepts in the mind of man.

If matter (mass) is removed, there is left only empty space.


__________________________________
Worth to remember: (:-)
In your own frame things are greatest (Length
Contraction) and fastest (Time Dilation)...

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