# Thread: I think I may have a misconception about the nature of light

1. Alright,

I don't see a particle as gaining mass as it approaches the speed of light. The fact it has more kinetic energy than it's *linear* velocity would indicate is irrelevant if it's moving in a sine wave path.

To measure it's kinetic energy, we'd have to ask ourselves how much of that sine wave it is traversing in a moment of time, not how much linear distance it has traveled.

My impression from what I've read of this is that the particle no longer treats straight as straight. It's concept of a straight line has changed. That doesn't mean it's gaining mass.

I mean, it makes sense to have a kinetic energy that's higher than that given by its linear velocity if it's isn't going in a linear direction. Is it gaining mass by some other measurement?  2.

3. Are you referring to light or a particle? Light doesn't have any mass.

Particles don't move in a sine wave path. They do behave like waves in certain types of experiments like the double slit interference experiment.

It's easy to get confused about this stuff due to the wave/particle duality of both light and subatomic particles. This has been baffling physicists for a long time.  4. So, particles don't begin to move in a sine wave path as they approach the speed of light?

I've been told light has no mass, though I'm not sure if that's just because its mass is too small a mass to detect or if it really has been proven to be zero.  5. Originally Posted by kojax
So, particles don't begin to move in a sine wave path as they approach the speed of light?
No, they don't. Where did you get that idea?
I've been told light has no mass, though I'm not sure if that's just because its mass is too small a mass to detect or if it really has been proven to be zero.
http://math.ucr.edu/home/baez/physic...ight_mass.html
By convention, relativistic mass is not usually called the mass of a particle in contemporary physics so, at least semantically, it is wrong to say the photon has mass in this way. But you can say that the photon has relativistic mass if you really want to. In modern terminology the mass of an object is its invariant mass, which is zero for a photon.  6. Originally Posted by kojax
Alright,

I don't see a particle as gaining mass as it approaches the speed of light. The fact it has more kinetic energy than it's *linear* velocity would indicate is irrelevant if it's moving in a sine wave path.

To measure it's kinetic energy, we'd have to ask ourselves how much of that sine wave it is traversing in a moment of time, not how much linear distance it has traveled.

My impression from what I've read of this is that the particle no longer treats straight as straight. It's concept of a straight line has changed. That doesn't mean it's gaining mass.

I mean, it makes sense to have a kinetic energy that's higher than that given by its linear velocity if it's isn't going in a linear direction. Is it gaining mass by some other measurement?
I may agree with you about the mass/energy variability of particles that I consider as unrealistic because those pricise tiny changes could be 'mind influenced'.

However, my perception of light is that it is a Quantum effect that differs from the regular EM waves that are continuous and form a 'sign' wave pattern.
What I am referring to here is the 'standing' waves that the electron radiates when in the ground state (GR).

When it is 'bumped' into an outer orbit and returns to its GS orbit to radiate a Quantum pulse of light known as a photon, these photon patterns form a 'black body' pulse rather than a sign wave pulse.
However, in the plasma radiations, these photon pulses would have a signwave pattern because here, the orbits are 'open' (hyperbolic) rather than closed.

So the light we see are the Quantum pulses rather than any continuous waves that are also EM in nature.

NS  7. Originally Posted by Harold14370
http://math.ucr.edu/home/baez/physic...ight_mass.html
Quote:
By convention, relativistic mass is not usually called the mass of a particle in contemporary physics so, at least semantically, it is wrong to say the photon has mass in this way. But you can say that the photon has relativistic mass if you really want to. In modern terminology the mass of an object is its invariant mass, which is zero for a photon.
The writer seems to believe that light has no mass, but most of the evidence and observations he presents seem it indicate it does, and little explaination is given as to why those arguements fail.

Light is subject to gravity. When present inside of a box it can contribute to that box's momentum, and it can fly through the vacuum of space. All this seems to indicate that it must carry some mass, albiet perhaps an amount that approaches zero.

The evidence he does give is a definition:
The definition of the invariant mass of an object is m = sqrt{E2/c4 - p2/c2}.
I guess: Mass = sqrt ( Energy ^2 / C ^ 4 - Momentum ^ 2 / C ^ 2)

Is that the right interpretation?

Most of my reasons for believing differently are just philosophical objections, kind of. If it is possible for energy to exist without mass, then I might expect it to be possible for mass to exist without energy. I'd also question any observation of absolute zero, because it seems to me that zero would be as difficult to detect as infinity.  8. From my understanding, light considered as a photon has zero mass but it can transfer momentum and energy. Its momentum is a function of its energy.

The momentum of a massless photon is determined by the formula:

momentum = plank's constant/wavelength or = energy of the photon/speed of light. (a photon's wavelength is determined by its energy)

The energy of a massless photon is:

E = plank's constant x speed of light/wavelength

So, we can measure the energy and momentum of a photon even though it has zero mass.

As to the possibility of mass without energy, mass is equilvalent to energy. To find the energy of a quantity of mass: E - mc^2, and to find the mass of a quantity of energy: m = E/c^2. So, mass and energy being intrinsically equivalent, we can't have a quantity of mass without it's equivalent quantity of energy.

As to a particle gaining mass as it approaches the speed of light, when we accelerate an object we are increasing its energy, and because of the equivalency of mass and energy, this added energy must be added to its mass. This is why increasing a particle's speed increases its mass.

Light is subject to gravity because light follows the curvature of spacetime.

Absolute zero temperature is the lowest possible energy state of a system.

You prob know all this already, just my thoughts on your post.  9. I wonder if the mass it has while in motion could be considered mass for all purposes, or just for the purposes of gravity, inertia, and the abilty to travel through empty space?

Only if you bring it's velocity down to a certain point, or down to zero, it kind of vanishes out of existence?

I'm still curious how well proven the zero mass claim is, though. I mean, skepticism is the most scientific way to approach anything. How certain are we of the zero mass?  10. For one thing, any particle which has mass >0 cannot be accelerated to the speed of light because its mass increases exponentially as its speed increases. A particle with non-zero mass traveling at the speed of light would have infinite mass and would require an infinite amount of energy to accelerate it to c . Photons travel at the speed of light therefore they must be massless.

Other reasons for physicists to consider photons as having zero mass is because if it had mass >0 the theory of quantum electrodynamics would be in trouble, the conservation of charge would be in doubt, Coulonb's law would not work, the behavior of static magnetic fields would have to be modified, etc.  11. So, if it had a negligible (very near zero) mass, it could come so close to the speed of light as to be indistinguishable from the speed of light.

It could also come so close to conserving a charge that the loss of charge would be nearly imperceptible. .......... and that has some very interesting implications.

If photons were losing their charge, that could explain the redshift. Maybe the photon emits a second photon of lower energy, then drops down to a lower energy itself.

If we assume that the loss is very slow, then what observed data would be upset by this?  12. In 1994 the Charge Composition Explorer spacecraft measured the Earth's magnetic field and physicists used this data to define an upper limit of .0000000000000006 ev for the mass of the photon. I think it may be impossible by experiment to determine if the photon has exactly no mass because there is always errors inherent in making measurements.

http://www.usatoday.com/weather/reso...photonmass.htm

But if the photon did have a very near zero mass, I suppose what you have said would be true. I don't know how much mass a photon would have to have to create the amount of red shift we observe in the universe. It's possible it would have to be greater than the above amount. Would be interesting to find out, though.  Bookmarks
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