[mxplxxx (OP)]

no, that's perfectly correct. the energy you measure a photon is dependent on what frame of reference you have, being 'at rest' with it or 'moving' relative it. To define a intrinsic energy you have to be 'at rest' with your experimental setup. Light can both be said to 'red shift' and 'blue shift' depending on ones frame of reference, measuring it. It's in principle similar to two cars colliding, depending on relative speed(s), but in the photons frame we better avoid talking about 'mass'.

Maybe only fermions have changeable state? and maybe it changes depending on the state of an interacting boson/ (rather that the boson actually causing the state change). This would place reality firmly into the realm of a finite state machine.

[alancalverd]

Energy is measured in joules, which are related to the definitions of mass, length and time. As stated above, a bolometer measures the absolute energy of photons.

[mxplxxx (OP)]

And an observer doesn't see a photon as ageless! Photons of considerable age will be redshifted according to Hubble's Law, so the energy of a photon compared with the expected energy of a freshly minted one from the same quantum process gives us an idea of how long it has been in the intergalactic outback.

I am aware of this. It seems to contradict relativity. Actually it may not. An EM wave is really three interacting waves/particles) ... but I will discuss this more in  New Theories, as soon as I have worked out how they interact:).

Actually, ridiculous as it may seem, it may make much more sense to think of photons as having an absolute speed of zero, which means that particles run into them rather than vice versa and the EM waves defines the energy of the photon and the problem of a photon having infinite mass does not arise. Not to mention there is no issue with accelerating the photon to the speed of light and having to account for that energy.

[alancalverd]

The problem of photons having infinite mass does not arise because photons have zero mass. There is no such thing as absolute speed.

Right now I am being bombarded with photons from the sun, a light  bulb, and this screen. The idea that I am running in at least three directions at once is absurd - men can't multitask!

[mxplxxx (OP)]

Right now I am being bombarded with photons from the sun, a light  bulb, and this screen. The idea that I am running in at least three directions at once is absurd - men can't multitask!

Fair enough:) Unless some other mechanism is also involved, like gravity.

[mxplxxx (OP)]

The problem of photons having infinite mass does not arise because photons have zero mass

Not according to e=mc2

[mxplxxx (OP)]

There is no such thing as absolute speed.

Except for SOL?

[alancalverd]

E equals all sorts of things: mgh, ½mv², QV, you name it. mc² is the energy released by the conversion of mass into energy - you can't have your cake and eat it!

The speed of light is a (universal) limit. "Absolute speed" implies a measurement against absolute coordinates, but all experimental evidence shows that there is no absolute coordinate - c is constant in all directions, regardless of the movement of the measuring platform.

[mxplxxx (OP)]

The speed of light is a (universal) limit. "Absolute speed" implies a measurement against absolute coordinates, but all experimental evidence shows that there is no absolute coordinate - c is constant in all directions, regardless of the movement of the measuring platform.

According to http://www.einstein-online.info/elementary/specialRT/speed_of_light.html

The speed of light is the only speed that is, in this sense, independent of the observer and thus absolute. It also plays the lead role in all of special relativity. First of all, it defines the absolute speed limit for the transfer of energy, matter and information.

[mxplxxx (OP)]

E equals all sorts of things: mgh, ½mv2, QV, you name it. mc2 is the energy released by the conversion of mass into energy - you can't have your cake and eat it!

I am pretty certain that physics teaches that mass and energy are equivalent.

[alancalverd]

Only very bad physics.

The dimensions of energy are ML²T^-2. The dimensions of mass are M. Obviously not equivalent.

[yor_on]

MP "  I would say that nothing that moves at the speed of light can be measured. "
Not really, you  measure photons daily by your senses. Seeing is one.

And thinking of seeing in form of photons is still a really big headache to me, as waves it becomes more understandable. Light has to be a duality.
=

the problem with defining it this way becomes how ones body interpret it? Does it 'choose' one way over the other? How can it 'know' that this should be waves? I can't see how 'photons' and 'waves' are the same, which puts me in a almost mystic position here as one now might presume that the way the body interpret is more than a passive receptor.

and Alan, I suspect MP was thinking of https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence
=

you might be able to argue that the eye can see both, but that the brain 'picks' waves as that interpretation makes the most sense to us, possibly?

[mxplxxx (OP)]

MP "  I would say that nothing that moves at the speed of light can be measured. "
Not really, you  measure photons daily by your senses. Seeing is one.

Not single photons it would seem http://math.ucr.edu/home/baez/physics/Quantum/see_a_photon.html.

In any case, photons we see are destroyed by the process which means? If we want to measure a photon, according to relativity, we need to be in the same frame of reference as the photon, but we can never attain the speed of light.

[alancalverd]

and Alan, I suspect MP was thinking of https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

Wikipedia is very precise in its wording:

In physics, mass–energy equivalence states that anything having mass has an equivalent amount of energy and vice versa,

my emphasis. Note "has" , not "is". I have £10 in my pocket, I am not made of money!

[alancalverd]

Many things cannot be measured without changing them. How would you measure the kinetic energy of a bullet? You could measure its speed, then stop it and weigh it, but in doing so you have dissipated the energy you set out to measure. Likewise the energy of a photon.

[syhprum]

You don't have to stop and weigh it you simply measure its path in a known gravitational field the same way as we determine the mass of planets around remote stars

[Bored chemist]

You don't have to stop and weigh it you simply measure its path in a known gravitational field the same way as we determine the mass of planets around remote stars

It's actually easier to measure the mass of ions and electrons when they are moving.
https://en.wikipedia.org/wiki/Mass_spectrometry

[mxplxxx (OP)]

You don't have to stop and weigh it you simply measure its path in a known gravitational field the same way as we determine the mass of planets around remote stars

So, ditto for a photon?

[chiralSPO]

You don't have to stop and weigh it you simply measure its path in a known gravitational field the same way as we determine the mass of planets around remote stars

So, ditto for a photon?

Unfortunately, photons don't have mass or charge, so this type of approach doesn't work.

[mxplxxx (OP)]

Unfortunately, photons don't have mass or charge, so this type of approach doesn't work.

But light is curved by massive objects? I wonder what determines how much it is curved by? Like most things photonic, this curvature is little understood. https://physics.stackexchange.com/questions/107930/why-can-light-photons-bends-in-a-curve-through-space-without-mass