[General] Position

[Mark, Martin van der]

Dear Richard,
Thank you for calling "light is heavy" excellent and also thank you for presenting the example of being confused.
Perhaps it proves that the paper is not so excellent after all in getting the idea across.

See my comments in blue....

Dr. Martin B. van der Mark
Principal Scientist, Minimally Invasive Healthcare

Philips Research Europe - Eindhoven
High Tech Campus, Building 34 (WB2.025)
Prof. Holstlaan 4
5656 AE  Eindhoven, The Netherlands
Tel: +31 40 2747548

From: General [mailto:general-bounces+martin.van.der.mark=philips.com at lists.natureoflightandparticles.org] On Behalf Of Richard Gauthier
Sent: woensdag 22 april 2015 19:33
To: Nature of Light and Particles - General Discussion
Subject: Re: [General] Position

Hello John D and John W. and others,
   I read "Light is Heavy" many years ago and found it excellent. I don't think it affects my argument. The energy of a set of photons has "rest mass" when they are confined in a box or confined by self-circulation. In its center-of-mass (center-of-energy?) frame the total momentum p of a set of confined  photons equals zero and so the rest mass m of this set of photons with total energy Etotal equals m= Etotal/c^2, as seen from the relativistic energy-momentum equation E^2=p^2 c^2 + m^2 c^2, which also applies to total E, p and m of a system of particles. If a box of photons is moving, the total mass m of these photons doesn't change,

Wrong. They will receive a net extra impulse from the opposite walls of the box (p=mc with c constant), as you say yourself:

but their total momentum p=gamma mv increases as does their total energy E=gamma mc^2.

But p is not mv , the velocity of the photons is and remains c at all times, v is merely the velocity of the box. The momentum increases because the mass increases. This is true for ALL physical processes, in fact. A car moving at velocity v has an additional mass compared to its mass at rest (the rest mass m0) exactly equal to its kinetic energy divided by c^2: Ekin/c^2 = m which at low velocity (the non-relativistic limit) is very nearly equal to ½ mv^2. So

E = mc^2 = sqrt[m0^2c^4 + gamma^2 m0^2 v^2 c^2 ]
So that
E=m0c^2 sqrt[1+gamma^2 v^2/c^2]
Which for v << c is
E = m0c^2 + ½ m0v^2 + ....

Any form of energy is massive ; The mass m is the most universal form of energy, it is the essence of energy and it gravitates like a mass m.

Note to David: It is all about physics but I express it in mathematics since that is the language of physics.

   In current usage in relativistic dynamics, the word "mass" and the letter m are taken to mean "rest mass".

Some people do that. It is a mistake because it leads to confusion and has been introduced as a result of previous confusion. Only the rest mass m0 is the invariant of a particle's (or closed system's) motion.

As you know, this is an invariant of a particle's motion. It doesn't increase with a particle's speed.

Correct

In this sense the mass of a single photon is zero, since it has no rest mass. But a single photon is still attracted by a gravitational field, since the photon carries energy.

Correct, and that energy is its mass times c^2

Saying that a photon has mass but not rest mass seems to me a statement more about semantics than physics.

Richard, from the above it should now be clear that it is not semantics.

Why not just say a photon has energy?

You are contradicting yourself, it has mass as can be concluded from the fact that the photon is attracted by gravity. It must have mass, gravitational mass so to speak.

For what it's worth, see http://en.wikipedia.org/wiki/Invariant_mass and http://en.wikipedia.org/wiki/Mass-energy_equivalence<http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence> .

Thanks for the links.

  If an electron is composed of a circulating photon there is nothing "at rest" in a "resting" electron. The term "rest mass" of an electron may be dispensed with in the future by replacing it with Emin/c^2 = 0.511 MeV/c^2 (as is generally done now in particle physics) where Emin is the minimum total energy of a free electron.

Wrong. The electron as a whole has a center of mass that can be stationary, all dynamics happening inside. Note that it ( it = the particle, the whole thing including boundaries or stabilizing forces, for example photon plus box) may be shaking about at the Compton or Zitterbewegung frequency. This random or periodic zero-point motion (by the book, quite a natural thing to have for a quantum mechanical object) is averaged out by a proper weighing experiment if one wants to know the total mass (being the whole energy). Remember, that energy is subject to the uncertainty principle with the length of time you measure it: The precise mass can be determined only if one averages over many cycles.

Our task as scientists is to shift our perspective on nature such that everything fits exactly. No more, no less.
You are one of the brave that have tried to do so, and you have been able to make a big step in the right direction, I believe.
This is why I put my precious time into this answer. However, some further tuning is required because your present point of view contradicts itself as well as reality. This true for the above as well as for the charged photon concept. Again, I am not saying it is all wrong, but there is a fatal misfit in places.
It is time to fine-tune your shift of perspective and I hope may comments will help you and others.

        Richard

On Apr 22, 2015, at 6:36 AM, John Duffield <johnduffield at btconnect.com<mailto:johnduffield at btconnect.com>> wrote:

Richard:

IMHO photon momentum is a measure of resistance to change-in-motion for a wave moving linearly at c, whilst electron mass is a measure of resistance to change-in-motion for a wave going round and round at c. In a box of its own making. And when you open one box with another in electron-positron annihilation, each is a radiating body that loses mass, just like Einstein's paper<https://www.fourmilab.ch/etexts/einstein/E_mc2/www/>. All of it. And hen it isn't there any more. Do read light is heavy<http://www.tardyon.de/mirror/hooft/hooft.htm>. It's very simple really.

Regards
John D

From: General [mailto:general-bounces+johnduffield=btconnect.com at lists.natureoflightandparticles.org] On Behalf Of John Williamson
Sent: 22 April 2015 08:40
To: Nature of Light and Particles - General Discussion
Subject: Re: [General] Position

Hello,

No. this is confusing mass and rest mass. Photons have "mass" by virtue of their energy. They are not massless but rest-massless and this is not the same thing. The popular literature confuses this. If photons were massless they would not be influenced by a gravitational field. Photons in a box make the box more rest-massive. You can weigh it! Free light cannot be weighed precisely because it is a gon. The box is at rest and whatever is in it it may be considered "at rest" as well. Forced to rest by being in the box.

Light confined in a box increases its effective rest mass in just the same way as any other mass-energy would. If the box is sufficiently sturdy then adding an effective number of joules of mass as a gas, as a photon gas or even as temperature would affect the rest-mass of the box in exactly the same way. The box aquires the properties of whatever is put into it by virtue of those things being confined in the box.

Regards, John.

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