# Light is most likely not a massless particle.

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I woke up this morning with light staring in my eyes. And I thought about the vastness of the universe, and how light is so much faster than human beings. It seemed unfair to me. But then I realized that it's not about fair or unfair, but the coldness of the physics. Light doesn't have morality, it just obeys the physics laws. It doesn't choose what speed to go, it just goes whatever speed it goes. And that was when I started thinking about this.

So this morning I googled whether light is massless particle, google tells me light is a massless particle but I don't believe it.

If light had no mass, how would a laser have knock back force?

Here is a conversation I found on google.

Quote

Q: Can a laser knock back someone, like in sci fi?

A: Photons have momentum. Incidentally, they don't have much

A: Although photons have no mass, they do still have momentum, equal to their energy divided by the speed of light: p = E/c

If a photon has momentum, then it has mass. The momentum equation is momentum=m*v. If a photon has no mass, then it has no momentum.

Here is an article from math.ucr.edu

The article seems illogical and doesn't make sense to me.

Again, if a photon has a very, very small amount of momentum, then it's momentum is equal to m*c. This means it has a very, very tiny amount of mass. But not a non-zero amount of mass.

Also, I view how the universe works as slightly different from most physicists. The way I view it, the heavier the object is, the harder it is to accelerate it. But this applies to everything, it's totally uniform. Light doesn't go infinitely fast because it has mass slowing it down. Anything with mass cannot go infinitely fast. The idea that something could go infinitely fast, would mean that it would have no mass, and thus would not exist, at least not in our human carnal frame of reference.

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5 minutes ago, eurekajo said:

Also, I view how the universe works as slightly different from most physicists.

Their view works...

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4 minutes ago, eurekajo said:

I woke up this morning with light staring in my eyes. And I thought about the vastness of the universe, and how light is so much faster than human beings. It seemed unfair to me. But then I realized that it's not about fair or unfair, but the coldness of the physics. Light doesn't have morality, it just obeys the physics laws. It doesn't choose what speed to go, it just goes whatever speed it goes. And that was when I started thinking about this.

So this morning I googled whether light is massless particle, google tells me light is a massless particle but I don't believe it.

If light had no mass, how would a laser have knock back force?

Here is a conversation I found on google.

If a photon has momentum, then it has mass. The momentum equation is momentum=m*v. If a photon has no mass, then it has no momentum.

Here is an article from math.ucr.edu

The article seems illogical and doesn't make sense to me.

Again, if a photon has a very, very small amount of momentum, then it's momentum is equal to m*c. This means it has a very, very tiny amount of mass. But not a non-zero amount of mass.

Also, I view how the universe works as slightly different from most physicists. The way I view it, the heavier the object is, the harder it is to accelerate it. But this applies to everything, it's totally uniform. Light doesn't go infinitely fast because it has mass slowing it down. Anything with mass cannot go infinitely fast. The idea that something could go infinitely fast, would mean that it would have no mass, and thus would not exist, at least not in our human carnal frame of reference.

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No Rest Mass, but has Relativistic mass as it has momentum.

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When physicists are saying "photon is massless particle" they really mean "photon has no rest-mass". Rest-mass is measured after slowing particle down. f.e. electron or proton can be accelerated nearly to speed of light (relativistic velocity). Majority of particle energy will be in kinetic energy, while minority will be in rest-mass (*c^2). To measure rest-mass of such relativistic particle, scientists slow it down, and pass through region of external electric field and/or external magnetic field, to see how particle will behave, how will turn in one direction or other direction, how many circles it will make..

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1 minute ago, Sensei said:

how many circles it will make..

What?

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10 minutes ago, John Cuthber said:

What?

x-ray photo from Bubble Chamber:

Path of charged particle (and therefore its trace) after applying external electromagnetic fields is deflected.

Edited by Sensei
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1 hour ago, eurekajo said:

If light had no mass, how would a laser have knock back force?

It has momentum but not mass.

1 hour ago, eurekajo said:

The momentum equation is momentum=m*v.

Only for objects with mass. For photons it is Plancks constant / wavelength.

1 hour ago, eurekajo said:

The way I view it, the heavier the object is, the harder it is to accelerate it.

This is Newton’s second law. It is about acceleration not speed.

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4 hours ago, John Cuthber said:

Their view works...

I'll believe it when I see it. So far all I see are some space shuttles exploding, Apollo 13 and gasoline automobiles. When we live in a utopia where we can teleport, travel the speed of light, and play internet games with no lag I will give the godhood medal to them. Science hasn't uncovered the mysteries of the universe, says its still looking for answers to the hidden secrets. Until they find all these hidden secrets, I remain a skeptic.

Like, I'll hire a scientist on my team of inventors, to make computers or new tech. But I'm not gonna have much faith on their ability to answer philosophical questions or give me reliable answers about the fate of the universe. Not yet anyway. Like Newton for instance. I'd hire him to build me a car. But his equations are not compatible with higher truths of the universe, or at least, so it seems. The equations only work within their applied boundaries. Same probably applies to modern science. I've heard Steven Hawking actually go back and denounce some of his own old views and theories. Can science explain how my consciousness ended up in my body, in the xyz coordinates of my brain? No. But there has to be some reason why. My brain has specific spatial coordinates.

4 hours ago, dimreepr said:

I don't see how I answered my own question. But lets use the energy equation since I didn't use it before. E=0.5*m*v*v. If light has no mass, then it has no energy. Yet, science says the energy of 1 photon is E 3.78 e-19 J. Therefore a photon has mass. But let's say you say, Newton is wrong, his equations don't matter. Check the Einstein equation. The Einstein equation says this. E²=(mc²)²+(pc)². Google says, "Besides being important for calculations on everything from celestial mechanics to rocketry, it's also important proof why anything with mass can't travel at the speed of light". How does it prove this?

3.78e-19*3.78e-19=(m*299,792,458*299,792,458)*(m*299,792,458*299,792,458)+(m*299,792,458*299,792,458)*(m*299,792,458*299,792,458)

Notice how in his equation, (mc²)² and (pc)² comes out to the same thing when applied to light. In any case, in order for his equation to be correct, you need the photon to have mass. P=m*v.

4 hours ago, Itoero said:

You should have a look what Special Relativity says about mass: https://en.wikipedia.org/wiki/Mass_in_special_relativity

I know what special relativity says about mass, it says if you have mass you can't go the speed of light. But in terms of the universe, that seems a bit strange mathematically don't you think? Isn't odd how all things in the universe are clamped to an arbitrary speed? Almost feels like it could be a computer simulation, where speeds are limited to a max constraint, or max float. Have you ever wondered why, all things in the universe cannot exceed a certain speed?

3 hours ago, Vmedvil said:

No Rest Mass, but has Relativistic mass as it has momentum.

Light is always moving, so it is impossible to measure it's rest mass. As to the reason light is always moving, I am not entirely sure. My guess is that, light has so little mass that when it touches any object, it immediately ricochets at a high speed.

3 hours ago, Sensei said:

When physicists are saying "photon is massless particle" they really mean "photon has no rest-mass". Rest-mass is measured after slowing particle down. f.e. electron or proton can be accelerated nearly to speed of light (relativistic velocity). Majority of particle energy will be in kinetic energy, while minority will be in rest-mass (*c^2). To measure rest-mass of such relativistic particle, scientists slow it down, and pass through region of external electric field and/or external magnetic field, to see how particle will behave, how will turn in one direction or other direction, how many circles it will make..

To be honest this makes more sense to me than just saying a massless particle. Now I have a few questions. Why does light slow down based on the medium it is in? Also, why does light have 100% elasticity to where it does not lose velocity during richochet.

Most bewildering is the idea that light is a particle. Because it seems to me, that light is simply a ripple of space, tearing through space. This would explain that why it bounces off something, it just loses it's frequency, eventually flat lining into nothing. But apparently it is a particle, which basically tosses that theory out the window

3 hours ago, Sensei said:

x-ray photo from Bubble Chamber:

Path of charged particle (and therefore its trace) after applying external electromagnetic fields is deflected.

What kind of particle? Electron or ion?

It doesn't look like one particle to me. It looks like several. This implies that reality is actually juxtaposed of several different dimensions  competing for the airspace of our consciousness.

3 hours ago, Strange said:

It has momentum but not mass.

Only for objects with mass. For photons it is Plancks constant / wavelength.

This is Newton’s second law. It is about acceleration not speed.

I said it was about acceleration.

But the rest sounds like circular logic to me.

Edited by eurekajo
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1 minute ago, eurekajo said:

I said it was about acceleration.

Well, you seem to imply that this also limited the maximum speed. Sorry if I misunderstood.

1 minute ago, eurekajo said:

But the rest sounds like circular logic to me.

Nothing circular at all. It is just how momentum is defined.

Is the problem that you learned the simple definition at school and assume that therefore that is it and it can never change? Sorry, but almost everything you learned at school is a simplification and once you go on to further study you find it is wrong/incomplete. It is a standard teaching technique known as "lying to children". (The same is true for undergrad, vs postcard and postgrad vs the world of work!) Also, many definitions change as we learn more. For example, fundamental particles have angular momentum (spin) even though they have zero size and don't physically rotate. We used to think that energy was conserved, now we know that mass-energy is conserved (locally). And so on.

And, if you picked up your physics from popular science articles, then it will be even more wrong!

4 hours ago, eurekajo said:

Here is an article from math.ucr.edu

The article seems illogical and doesn't make sense to me.

Can you say which bits don't make sense? Maybe someone here can explain it.

However, as he says, people don't just take this as a given. Experiments have been done to measure the mass of the photon. As far as we can tell it really is zero.

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What's the lower bound on the photon mass again, its some ridiculous ten to the minus power of something. I do not recall now.

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5 minutes ago, Dubbelosix said:

What's the lower bound on the photon mass again, its some ridiculous ten to the minus power of something. I do not recall now.

Something like that dubblesiox extremely low.

Edited by Vmedvil
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An upper limit to the photon mass can be inferred through satellite measurements of planetary magnetic fields.  The Charge Composition Explorer spacecraft was used to derive an upper limit of 6 × 10−16 eV with high certainty.  This was slightly improved in 1998 by Roderic Lakes in a laboratory experiment that looked for anomalous forces on a Cavendish balance.  The new limit is 7 × 10−17 eV.  Studies of galactic magnetic fields suggest a much better limit of less than 3 × 10−27 eV, but there is some doubt about the validity of this method.

(From the John Baez link above)

Pretty close to zero.

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Ya that papers says "which a bound of m 10-38 grams emerges".

Edited by Vmedvil
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42 minutes ago, eurekajo said:

I know what special relativity says about mass, it says if you have mass you can't go the speed of light.

Actually it doesn't.

The equation actually shows that the relativistic mass v speed curve becomes asymptotic to infinity at the speed of light so is not determinable from that equation.

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1 hour ago, eurekajo said:

What kind of particle? Electron or ion?

Electron is stable particle.. so its trace is curve (in strong external electromagnetic field), without new traces coming from the end.. Because it doesn't decay..

However, it could annihilate with positron (electron's antiparticle), and change to two (or more) gamma photons.

1 hour ago, eurekajo said:

It doesn't look like one particle to me. It looks like several.

Yes, it's dozen of particles. High energy unstable particle, decays to a few new more particles, then they decay a while later to few more, as so on, until they are all stable (or they annihilated).. and it ends up in image like I showed.. Bubble chamber is quite old technology, but what they make is visible on photos (500+ x-ray photos made in fraction of second right after collision between stream of protons (or other ions) at target).

Physicists analyse these traces, and figure out which particle decayed to which other, and analyse their decay modes (high energy particle has usually very large number of decay modes).

1 hour ago, eurekajo said:

This implies that reality is actually juxtaposed of several different dimensions  competing for the airspace of our consciousness.

No, it doesn't imply anything like that..

Edited by Sensei
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1 hour ago, eurekajo said:

I know what special relativity says about mass, it says if you have mass you can't go the speed of light. But in terms of the universe, that seems a bit strange mathematically don't you think? Isn't odd how all things in the universe are clamped to an arbitrary speed? Almost feels like it could be a computer simulation, where speeds are limited to a max constraint, or max float. Have you ever wondered why, all things in the universe cannot exceed a certain speed?

The mass (invariant+relativistic) and force decides imo the speedlimit.

Edited by Itoero
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Well, Technically there are particles that do go slightly faster than the speed of light but this causes them to give off Cherehov radiation like the higgs boson gives it as rest mass for particles generated, where electrons going faster than the speed of light in a material will cause the same effect which is not actually faster than the speed of light but faster than light's speed in that material, it causes them to become unstable or however you would like to put it and start to bleed off energy as photons.

So, if you are going above  light's speed in anything quickly you will lose the energy moving you above that as some sort of particle.

This is one thing that unchanged SR is dead wrong about, but it is still very close to real universe in its predictions, because it goes undefined above C.

Edited by Vmedvil
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36 minutes ago, Vmedvil said:

This is one thing that unchanged SR is dead wrong about, but it is still very close to real universe in its predictions, because it goes undefined above C.

Thank you for posting the asymptotic curve.

Yes I often make this point that SR is undefined or unknown above c. Though I do not go as far as refuting SR. +1

There are other more prosaic phenomena in Nature and mathematics which show this behaviour (such as the specific energy line in fluids). These have more than one type of recovery once the critical value is passed.

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Well, I am not saying it is wrong but Einstein missed something which he would have no have know about C = n t, so C= n2 t2  , since this was not found out until the 50's and this was made back in the 10's SR, he never took in account his own time dilation effect on C. n increases as Time dilates thus C does too.

Edited by Vmedvil
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46 minutes ago, Vmedvil said:

This is one thing that unchanged SR is dead wrong about, but it is still very close to real universe in its predictions, because it goes undefined above C.

It is undefined at c. Not surprisingly. That doesn't make SR wrong.

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2 minutes ago, Strange said:

It is undefined at c. Not surprisingly. That doesn't make SR wrong.

Read the post above you, I never said wrong just incomplete.

Edited by Vmedvil
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2 minutes ago, Vmedvil said:

It appears to be wrong. c doesn't change for any observer. Perhaps I have misunderstood your point.

What is c = nt? (what is n? what is t?) Where did you get that from?

Edited by Strange
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2 minutes ago, Strange said:

It appears to be wrong. c doesn't change for any observer. Perhaps I have misunderstood your point.

What is c = nt? (what is n? what is t?) Where did you get that from?

Cherenkov Radiation equation and n is the index of refraction of the material being time-space in this context.

Edited by Vmedvil

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