Is Time Influenced by Mass and Matter?

[DaveC426913]

Matter takes up space... So if an "object" had no mass, it wouldn't take up space. So itwouldn't follow the path of space. Right? Thoughts...

On what basis do you build your logic? Common sense? Analogy to classical mechanics?
None of these apply.

A photon behaves how a photon behaves.

A Bornean bushman would try to understand how a Blackberry works based on his understanding of yodeling and smoke signals. And we would tell him "there's no counterpart in the world you're familiar with. It is what it is. We'll happily show you the math, but don't bother trying to relate it to anything you're used to."


I'll try to explian it once again: You seem to be thinking that, somehow, even though space is curved, the photon should ignore this curve and ... what? go straight? As if the curve of space is somehow mapped onto a "higher", more "real" space where things are "actually" straight? There is no "higher space" where the photons would somehow know what "true straightness" is.

No, the photon follows a straight path. Because that's what photons do. They go straight. They always go straight.

The issue here is that "straight" is defined by the force of gravity.

 

[Mzachman]

Here is my thought. And it's just a thought from someone who probably knows nothing. So tell me if I'm wrong if I am. haha

Ok, your "effective mass" comes from E=mc^2, correct? We know that the photon has no rest mass. So by having no rest mass, but having "effective mass", that means it has some sort of energy through E=mc^2.

In this case it is the energy that we know the photon carries. So if you could somehow "stop" the photon without releasing that energy, it would have mass... rest mass. Only problem is that the photon IS energy itself, and travels at one speed ONLY. Meaning, if you stop it, all energy is removed (put into something as heat, etc.). By all energy being removed, it means it literally doesn't exist anymore. This proves that it has no true mass. It may have an "effective mass" and momentum through E-mc^2 and p=h/lambda, but if you try to "stop" the photon, all of the energy it contains leaves, and leaves no energy or mass whatsoever...

That didn't come out nearly as clearly as it was in my head. I'm kinda new at getting those things out... but maybe it will start an idea and someone more experienced in this can speak up. I hope it helps a little bit.

 

[stone1]

When a nuclear (uranium, for example) bomb explodes, lot's of light (photons) comes out. Where were these photons before the explosion? Binding the atom. Was the mass of the atom affected by the binding energy? You bet. So where is the issue?

 

[protonchain]

hi Timmaay,
actually, E = mc^2 was a bit misleading, and might cause your confusion.
In fact, the whole equation is
E^2 = (pc)^2 + (mc^2)^2.
As you can see, it also included an extra term of momentum. Now, do not think Momentum in the classical sense, that is, p no longer equals to mv.
So indeed, it is possible for photon to not have "rest mass", it just simply means that all of its energy is contributed to momentum (or in another way, kinetic energy).

QFT

The energy of a photon is basically E = \frac{hc}{\lambda}

h is a constant, c is a constant, \lambda is the wavelength. No mass needed.

Now let's wait for timmay to go "I still am not convinced that photons don't have mass."

 

[cragar]

E=hf

 

[benk99nenm312]

Well first of all that doesn't convince me that a photon is massless...

Photons have relativistic mass. Does that satisfy you?

A photon is massless. Sorry.

 

[Naty1]

Timmaay:
I don't think it's particularly important for you to believe that photons have no mass, maybe it's better you don't believe it, but it is important to accept that current science says that's the case. The current explanation is that photons do have energy and since mass and energy have some deep connection, both energy and mass happen to curve spacetime. Nobody knows why yet.

Einstein did not believe that space and time were fixed and immutable when everybody else did;instead he thought the speed of light was fixed and immutable. He understood the conventional explanation at that time produced anomolies which he did not believe. So he created a new theory, one that was logical and could be verified experimentally. He turned out to be right!

Since nobody even knows what mass and energy really are at a fundamental level, maybe its useless to argue about these two different forms of what is likely a unified (single) entity. All we know today is that they appear different to us and E = mc² explains the observed relationship.

 

[Dale]

By the way, there is no way to experimentally confirm that a particle has 0 mass. All you can do is put an upper bound on the mass. Specifically, if an experiment determines the mass to be zero to within experimental error then the experimental error itself becomes an upper bound on the mass. Currently, the best upper bound on the http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html" is 7E-17 eV/c² (1.2E-52 kg). So the assumption of 0 mass is pretty reasonable IMO.

 

[protonchain]

By the way, there is no way to experimentally confirm that a particle has 0 mass. All you can do is put an upper bound on the mass. Specifically, if an experiment determines the mass to be zero to within experimental error then the experimental error itself becomes an upper bound on the mass. Currently, the best upper bound on the http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html" is 7E-17 eV/c² (1.2E-52 kg). So the assumption of 0 mass is pretty reasonable IMO.

I guess apart from measuring the mass/estimating it, we can usually assume that something has to have 0 mass in order for it to reach c right?

 

[Dale]

Right, but the same statement applies. We cannot experimentally confirm that a particle travels at exactly c, all we can do is determine the speed to be c to within experimental error.