Unraveling the Mystery of Photon Mass and Its Interplay with Gravity

[Eepl]

A photon isn't supposed to have mass. But yet it is effected by gravity. So this means that a photon must have the gravitational property. And this would give it mass. So why does gravity bend the curve of a photon? And please give me more than "gravity bends the spavetime continuum, so it effect the curve of the photon". Cause as I see that, bending in spacetime in towards a massive object would push the photon away. Cause there would be more "preasure", if you will, closer to the massive object, therefore pushing the photon away. And in that case, wouldn't you age slower on a still massive object then you would being still in space?

 

[Eepl]

Then spacetime would have to be a force, like a wave or something? Because unphysical things wouldn't be able to affect something that is physical. Like how could your imaginary friend kill your other friend. But then an object that does not have that wave type cannot be affect by the wave. So then the photon would have to have the gravitational wave type so it could be affected by spacetime. And this would give it mass.
And gravity would seem to have a physical property making it a wave type(aether), thus it would affect space. And because it affects space it in turn affects time. So time would be a wave. And the two would work together to make "spacetime" which allows us to travel through this three dimensional space. Cause with only time you're everywhere, and with only space you're nowhere. So the two together give us what we are living in right now.

sorry, long day.

 

[Eepl]

I had to reread the above before I saw that it made no sense. So I edited it. Please reread if you haven't already.

 

[Sniper__1]

spacetime itself is not real because time is not real so why don't you all be quiet about space time. Oh and the whole photon mass thing is not ecxactly untrue but things with no mass are stiil affected by mass so a photons curve is nnot unnusual at all given that time does not exist.

 

[Eepl]

Ok, so spacetime isn't a force or a wave. Then it can't directly affect physical objects. "How can your imaginary best friend kill your physical best friend?" I can't think hard then affect which way my car is going to go, so how can something that doesn't exist in reality even have a number in a mathmatical equation. My physics teacher tried to tell me that "that's just the way it works". Sorry man, won't take that. Only the physical can affect the physical. So if spacetime has no physical properties then how can it affect physical things. Like pulling in a photon. If the photon has no mass, then it has no gravity. Therefore it won't be pulled into a planet by gravity, but how can it follow the curvature of spacetime if spacetime is only an imaginary thing.

You said "(Changes in the geometry can propagate as waves, though.)" But that is after the fact. After a tragectory has been changed it will propagate a wave, but what got it to change course in the first place.

And the sum of everything else that I said was, space and time are two different wave types working together to give us three dimensional space, or spacetime. The fourth dimesion is an illusion of the resulting effect.

 

[Sniper__1]

actually you could move your car with your mind and destroy it and recostruct it into anything even solid gold STUDY QUANTUM PHYSICS!

 

[Nommos Prime (Dogon)]

Photosynthetic Absorbtion

Solar photons can add Mass indirectly to plants through photosynthesis. I know this does not endow a photon with Mass, however it does ADD Mass to a plant.

 

[Sniper__1]

really though the mass added is from the water not the solar photons they just change the mass.

 

[toe21k]

https://www.physicsforums.com/showthread.php?s=&threadid=9777 :-

Hydrogen's Mass or 'Weight' is 'negative'?

 

[wolram]

spacetime itself is not real because time is not real so why don't you all be quiet about space time. Oh and the whole photon mass thing is not ecxactly untrue but things with no mass are stiil affected by mass so a photons curve is nnot unnusual at all given that time does not exist.
--------------------------------------------------------------------
who was it that said "fools rush in where angeles
fear to tread"?
i struggle with nonintuitive theories all the time
but the bottom line is, unless one has a better
theory its all we have, many many people have dedicated
their lives trying to bring about a better understanding
of science, and many more have learned the theories
that these have people have formulated, so if you
want to ignore this wealth of information it is up to
you, maybe some of you could formulate your own
theories and re write science, when you have a theory
share it with us and we can kick it around and see
if it holds water.

 

[Eepl]

Sniper___1, I have studied quantum mechanics, and like Einstein I have decided that there cannot be chaos in the universe. There only seems to be chaos because our puny brains can't handle everything yet. Though this always interferes with the positivist point of view that I try to hold. But in this case it becomes religous.
Placks problem with trying to measure the speed and the possition at once was he was trying to do it on a three dimensional level. Though time adds a fourth dimesion, so the fourth dimesion could be graphed on a different three dimensional chart, put the two together and I believe that the uncertianty principle could be taken away.
Wolram,...

Ambitwistor, that thing at the very end was the start of a new theory I'm developing. And yes I will post it in the Theory Development when it's done. BUT, I have to bring up some aspects of it so I may prove my point.
You said "There is no law of physics that says that something has to be either a force or a wave to affect physical objects." Never mind about the wave thing, but all "forces" exert physical activity, thus giving it physical properties. And later you said that we can measure the curvature of spacetime, so doen't that mean spacetime has physical properties. You said that "geometery" was a physical property. Please explain that, I don't rightly understand.
More clearly what I was trying to say with the mass gravity thing was that gravity is the only force that bends spacetime, and the bending of spacetime affects only objects with mass. But to have mass you also have to have the gravitational property. So what I'm saying is for a photon to travel with the curvature of spacetime it has to work on it's level, so it would have to have the gravitational wave, which would give it mass. I figure that the mass of the photon can be calculated off the amount it curves around a massive object if the mass of the object is known and how far away the photon is.

 

[Eepl]

Originally posted by Ambitwistor


the geometry of spacetime affects everything, mass or not, because everything exists within spacetime.

Then you're saying that gravity directly effects the electromagnetic bubble (sorry, can't think of the right word) around the earth. As I've seen gravity can effect the particle in spacetime thus effecting the electromagnatism it produces, but never be able to effect the electromagnetic effect the particle produces directly.

Scientists say that electormagnatism travels at the speed of light (this is where I always get confused) but then you have the effects created by those electormagnetic waves.
So the path of the electromagnetic wave is c, then wouldn't the curvature of the electromagnetic wave be greater then c? And how fast does the electromagnetic effects travel through space?

 

[Eepl]

I don't know enough about electromagnetic fields to argue my point well enough. Would you know of any reading material that I can use?

So they say that electromagnatism travels out like particles, but behaves like waves. This is where we get particle-wave duality. When you see a picture of a electromagnetic wave it shows the wave traveling up and down, and at 90 degree angles to it. But do those waves "emit" more waves that effect other things? Like a fish swimming though the ocean. The fish is the origin of the wave, but then waves are created from that and travel even further. And if that is, what is the speed of those waves?

 

[SmarterThanGod]

Originally posted by Eepl
"How can your imaginary best friend kill your physical best friend?"

What your missing is that spacetime is NOT imaginary. Your imaginary friend can't kill your best friend, but a car falling off a cliff due to gravity sure can. Gravity is real, and therefore, space is real. And if space is real, then time is real. Even though a photon has no mass, it is still subject to the same laws as massive objects. Space and time are both real, metaphysical dimensions. The problem is that you are all thinking of being "real" as being an object, instead of dimensions and thigns of that sort. As to the original inquiry, I believe that all particles are subject to the same laws, regardless of mass, or lack thereof.

 

[Sniper__1]

Smarter than god




TIME IS NOT REAL IT IS A MENTAL CONSTRUCT OF THE HUMAN MIND IT CANNOT "TRULY" BE MEASURED AS ENERGY OR MASS AND IT HAS NO REAL DIMENSIONS AS SHOWN IN EXPERIMENTS "TIME" DIFFERENTIATESS AND BEING THAT IT HAS NO PROPERTIES OF MATTER< ENERGY OR A CONSTANT IT IS NOT REAL! [zz)]

 

[Eepl]

So you're saying that in the 'time' that it takes for the synapsis in your brain to even phathom this subject, it's not real. Time is real. A measurement of how long it took to travel a distance in space. It's funny how something so 'fake' can be part of this reallity we call life.
I wrote something on this in the Theory Developement section under 'SmarterThanGods' last post to help him out. You might want to read what I think of spacetime.

 

[russ_watters]

Originally posted by Sniper__1
[zz)]

Yeah. That was my reaction to your post too.

You said that "geometery" was a physical property. Please explain that, I don't rightly understand.

I'll see if I can expand on what Ambitwisor said since this is a little bit tough. When talking about geometry on a flat piece of clear, flexible plastic (like an overhead projector slide), things are easy: you draw a square, you can see its a square, life is great. That's geometry of a 2D object on a 2d space. But you can't really see the space, can you (its clear)? How do you know its flat? How do you know where the edges are? - what if you don't even know if it HAS edges? That makes it tough to describe the geometry of the piece of plastic itself. Now what if you bend it? Now it is (sorta) 3 dimensional. The square you drew now looks like a rectangle in your 2d vision (your vision is a 2d projection of 3d space). But again, if you can't see the plastic itself, how would you know its bent? You know because of the geometry of square you drew on it. You know it was a square because you drew it.

This is how space works. Space is 3d curved in 4d (or something like that - I'm not sure we really know how many dimensions there are - but we can see 3 space dimensions). How do we know its curved? We know by observing the way objects behave in space. We observe light getting (apparently) bent when going near massive objects. We know that light has no mass, so how can it be affected by gravity? Well it can't - thus the apparent bending of light must actually be a bending of space itself, making the light to APPEAR to bend its path.

 

[Eepl]

russ_watters, thanks for trying to clear that up. But there is one thing I have learned, and that is to never try to think in 2D. Think about it. We have no real comprehension of what only 2D is. I mean could you even see in 2D? I just try to figure everything how it already is.
Has anyone ever considered that there are only two dimensions, time and space. Each could be graphed out on a x,y,z axis graph, then we would kind of have six dimensions. I mentioned this earlier with Plack's uncertainty principle. If you were to map out where a particle is in space and time sepratly then there would be no uncertainty. The exact location and velocity would be known at all times.

 

[russ_watters]

Originally posted by Ambitwistor
If you're going to argue that massless particles aren't affected by gravity...

Sorry, poorly worded. How about "attracted?"

 

[russ_watters]

Originally posted by Ambitwistor
Massless particles are attracted by gravity in the same sense that massive particles are.

?? A massless particle will not follow the same path past a massive object as a particle with mass would, correct? Due to a different gravitational interaction, the particle with mass will have its path bent more.

Hold a hypothetical massless particle in your hand and you feel no weight and it has no inertia if you throw it.

I don't know how you would describe that, but that's all I was trying to convey.

 

[Eepl]

Light coming in from the sun has radiation, which effects things. The electromagnetic waves of light allows us to see. This is from the light creating chemical reactions in the back of the eye. But if a photon had no mass wouldn't it flow around the chemicles in the back of the eye. It has to create a force, a push if you will, that makes that chemical reaction. But if there is nothing to push against then nothing can move.
What I'm trying to say here is that because photons effect things with mass they themselves have to have mass. Or else wouldn't the photon flow around everything?

 

[Eepl]

K, a massless particle may exert a force. But because it's massless the particle can't move anything. For every amount of push forward it has to have an equal or opposite push back. One of Newton's laws. ex. An ant pushing a tank.
What I'm saying is that if it had no mass then there would be nothing to push against. The photon would just bounce off all matter, and nothing would happen.

 

[russ_watters]

Originally posted by Ambitwistor
No, but its path is determined by its speed, not its mass. (Galileo's observation. Of course, it is true that a massive particle can't travel at the same speed as a massless one.

I'm not sure what you mean by "a different gravitational interaction" here ...

... if you shoot two planets past a star at different speeds, the slower one will have its path bent more, but that's not because the force of gravity upon it is any stronger than on the other.

If the deflection is different because the speed is different, that's still a difference, right? And its speed is most certainly related to its mass: a particle with mass can't travel at the speed of light. Yes, two particles with mass will follow different trajectories if they are at different speeds, but neither will follow the trajectory of a massless particle.

So its still correct to say a particle with mass will behave differently here. It will follow a different path than a particle without mass - the fact that two particles with mass may also follow different paths is not the point. The point is neither will ever follow the same path as a particle without mass (unless maybe falling straight toward the massive object). Is this because of the mass or the speed? Is the speed related to the mass (mass certainly has a speed limit)? Chicken? Egg? Does it matter?


In any case, clearly I don't quite have the physics vocabulary to express this stuff quite right. I understand everything you are saying - sorry if I express it incorrectly.

 

[Eepl]

Here is as simple as I can put it.

Less Mass=Less Force. No Mass=No Force. 1=1, 0=0. If it has no mass it cannot move other mass.

 

[GijXiXj]

Can I join in?

Would things not be a whole lot easier if we just forgot this whole concept of mass thing altogether?

I mean to regard mass as just another manifestation of energy, something like heat is (or other vibration types, perhaps mass is just another vibration type: QM, anybody?).

So in regard to behaviour of photons, it's not their mass or lack of that's important, but that they also too are a manifestation of energy - perhaps the fundamental manifestation.

Further in regard to GR, is there anything wrong with saying that it's not mass, per se, that warps space-time, but the energy (E = mc2, and all that, roughly) that that mass is a manifestation of.

So energy (whatever that is!) warps space-time, causing the appearance that energy attracts energy. Hence the Sun appears to bend light towards it (like refraction), 1919 Eddington experiment, and all that.

Thanks.

Dennis Revell

 

[GijXiXj]

Originally posted by Ambitwistor
"Unlike energy, mass is an intrinsic, invariant property of a particle, and as such, is a useful physical property."

Is it? What about E = mc2? Mass, as commonly understood certainly isn't invariant when it's changing velocity. What about the spontaneous destruction of mass to create photons?

The viewpoint I proposed is more shocking than may first appear. It also covers the idea that there is no such thing as particles. That "particle" interactions are no more than the interactions between different ("particle") forms of energy. Another way of looking at it is that this or that particular particle name is just convenient code to describe how that particular "particle" manifestation of energy behaves. But I think too much emphasis on a particle as a particle, implying some form of solidity is confusing.

If a billiard ball hit me on the head it would certainly hurt; but as you know, a billiard ball is far from solid (whatever that means), comprising mostly empty space (whatever that means). As you try to look at the billiard ball under higher and higher magnification it looks less and less solid, and the "electrons" around its atoms disappear into diaphanous clouds of ... something ...; but you certainly never get to "see" them.

"Their masslessness has important consequences; for instance, it's the reason why they can travel at the speed of light."

Yes, I realize that photon masslessness has important consequences; they probably also all enjoy a "time-free" existence ('til they hit something that's non reflective, that is). That said there's something a little tautological in what you say: " ... the reason they can travel at the speed of light"? They ARE light.

Unlike energy, mass is an intrinsic, invariant property of a particle, and as such, is a useful physical property.

Is it a physical property? Or just useful shorthand that summarises a wide spectrum of behaviours? When you say here's a particle mass (rest or otherwise) of such-and-such, aren't you just saying here's a really tight little bundle of energy = mc2?

 

[selfAdjoint]

The "no particles, only fields" idea isn't shocking, it's been widely circulated among the folks who write about interpretation because they can't do (or are burnt out on doing) theory.

The counter to all-field theories is Haag's theorem that a pure interacting quantum field theory can't hang together at the Hilbert space level.

 

[GijXiXj]

selfAdjoint & Ambitwistor:

The "no particles, only fields" idea isn't shocking, it's been widely circulated among the folks who write about interpretation because they can't do (or are burnt out on doing) theory.

Well, I hope that's not meant to imply that those who are "burnt out" shouldn't post here. ;-)

I didn't really mean to imply that the alternative to particles is fields (although it might be, and although I know I mentioned vibrations). Who knows what it might be? May be a scalar "Energy" that needs to stuff itself somewhere for uncertainty principle or similar or perhaps I mean analagous reasons, and so the four space-time dimensions being insufficient for this stuffing, the "energy" (whatever that is) goes (went) right ahead and created extra dimensions over and above the "standard" four into which to stuff itself: which particular quite transmutable form of energy comprises what we know as matter?

______________________

When we speak of photons being massless, which is what this thread is about, the mass involved is the invariant mass.

Actually I understood the thread to be about Eepl's confusion/misinterpretation of the consequences of the "masslessness" of photons. I tried to address this by effectively saying "forget mass, think energy", which viewpoint really should make Eepl's problem go away: of course no one has yet disputed that it is energy, per se, and not mass that warps space-time. So, if the Sun has "mass" energy (I might want to call it, burnt out old windbag that I am: the "mass manifestation of energy"), the photon has EM - pure? energy, that should go some way to helping Eepl.

Energy is conserved, so it's an interesting quantity, but it's not invariant. Mass is invariant, so it's also an interesting quantity, but it's not conserved.

I'm sorry, I'm out of touch. Could you explain more rigorously the difference between "invariant" and "conserved"?

There is a difference between invariant and conserved.

As above. My rough understanding is that "invariant" applies to a process, "conserved" to a quantity (although I know that dS^2 = GijdXidXj - aka Pythagoras, and other quantities are regarded as invariants). Mass is obviously not "invariant" if we agree to speak in plain English: it varies (changes). Energy, as commonly accepted, doesn't change in overall amount (well, may be ... unless that turns out to be relative too - in which case we're screwed ;-).

That's missing the point, which is that anything which is massless can travel at the speed of light. As such, "the speed of light" is something of a misnomer; there is a maximum, invariant speed that things can travel at, but only if they're massless.

And do you happen to know, I mean for sure, of any such other "things"?

Is [mass] a physical property?

Yes. We can measure it.

Hmmm. How do you know you're just not measuring the property that mass is "merely" ;-) another manifestation of energy, one so "dense" in energy that it exhibits measurable inertia (resistance to change)? If I heat an iron bar up, does its gravitational "pull" not increase, or more correctly, does it not "tighten up" the space-time around it, and does it not become "stiffer" with regard to trying to change its state of motion? In other words, have I not increased both its gravitational and inertial mass - which have varied no matter how little I heat the bar? Or are all those just stories told to school children to impress them with Relativity?

______________________

I guess as I'm arguing against too much emphasis on the validity of the concept of mass and particles, that I should also do so against the concept of photons. Aren't "they" just a manifestation that energy exchanges with radiation occur in discrete amounts, and that is equally validly (or more validly) regarded as a property of the object interacted with, or may be even space-time itself, than as a property of the radiation? In other words a photon comprises the lowest sub-multiple of an amount of energy that is allowed to be exchanged whenever radiation is involved? The photoelectric effect seems to argue for this viewpoint: radiation of a certain frequency won't cause electron emission from one substance, whereas it will from another.

______________________

Just thinking aloud. ...

 

[Eepl]

AND E EQUAL MC SQUARED.

I think that we are far beyond accomplishing anything here. It's very simple really. Does a photon have mass? Yes or No. Use the right math and you'll get the right answer. No names, no theorums, just good ol' fashion math and common sense will get you the answer. This is no longer trade of knowledge, but a battle of technicalities. What we are doing here is what has destroyed the new discovery of science so many times.

May I recommend that a Administrator close this thread.

 

[GijXiXj]

Eepl

Your signature reads:

"Imagination is more important than knowledge."

-Albert Einstein

And then you say:

"This is no longer trade of knowledge, but a battle of technicalities. What we are doing here is what has destroyed the new discovery of science so many times."

Now, I agree that my imagination might be a bit wild, as evidenced perhaps by Ambitwistors: "The rest of your post was too incoherent for me to respond to." (Who rattled his cage?). I'm not trying to battle technicalities. I seriously thought that regarding everything more or less as energy might help you overcome your difficulty with "massless" photons. The idea is that if you regard mass as just another manifestation of energy that you get pulled away from the idea you seem to be stuck with that only "material" things can exert influences.

Note that no one has argued against the contention that it is energy that warps space-time, rather than mass.


"AND E EQUAL MC SQUARED."

Which equation, of course, includes ALL mass, no matter how "generated".

"I think that we are far beyond accomplishing anything here."

Please yourself. It's "your" thread.

"It's very simple really."

No, it's not.

"Does a photon have mass? Yes or No."

No it doesn't. Entirely logical if you just regard mass as one form of energy and "photons" as another. If so, your question becomes: "Does one form of energy comprise another form of energy". A question that ridicules itself. As in: does sound have mass: no it doesn't, but it does have energy (OK ... don't stretch this too far ;-).


"Use the right math and you'll get the right answer."

Erm ... just who's to decide, or how do you decide just what the "right" math is? There's an awful lot of it out there ... and it's all "right" within limitations. In fact, it's hard to for me to see how math can be wrong. It might be incorrectly applied, but it can't be wrong in itself - it's an abstraction ( er, may be it's not ;-).

"No names, no theorums, just good ol' fashion math and common sense will get you the answer."

Well, er, theorems are part of "good ol' fashion math"; and common sense really gets you nowhere, unless "common sense" indicates that time slows down as you go faster (whatever that means, time actually speeds up if you hop on a west-bound airplane), you get "heavier", and you get smaller.

I don't think any of those fall within most people's definition of common sense. What does get you somewhere are observations, and then trying to create mathematical frameworks to fit those observations, as well, of course, as Einstein said, imagination.

"May I recommend that a Administrator close this thread."

Yes, you may.

;-)

Ambitwistor:

Yes, thanks for your explanations of "invariant"/"conserved". That's more or less how I thought it was. I'm a bit rusty on some things.

That said the split between "invariant mass" and "relativistic mass" seems artificial to me. Isn't one alien space-being's invariant mass another alien space-being's relativistic mass? How would they tell the difference? Are there any equations that indicate a difference; I mean for all conceivable observers (from whichever galaxy)?

Gluons are massless?:-

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/expar.html

(may be that's all old stuff)

Gluons are still not totally hypothetical? Not just another way of explaining energy exchange? Or perhaps a way to insist, with really no definite evidence, that a nucleus somehow actually looks a bit like a bunch of the things it is known it can decompose to: neutrons, protons - as if an "electron" in an orbital actually "looks like" or behaves much like a free "electron". It doesn't.

Yes, but you're talking about relativistic mass (which most people today just call "energy" or "mass-energy").

But ... is there any way of telling the difference between "invariant mass" and "relativistic mass" ... I don't mean by sending the "mass" off in a spaceship, and work it out from the equations. I mean by measurements. So, I've got a lump of metal, I'm moving in some way, because I'm on the Earth (a spaceship!), what experiment can I do to tell me how much of the "mass" of the metal is of the "invariant" type, and how much of it is of the "relativistic" type? Presumably also, this ratio changes as the Earth's rotation slows down. But ... is there anyway of detecting it?

The rest of your post was too incoherent for me to respond to.

Really? I thought it was quite coherent. That doesn't mean anything in it might in any way approximate to reality, but I think that also goes for what "most people today" think. Perhaps you just didn't understand my meaning.

 

[GijXiXj]

Fair point.

If you want to measure its invariant mass, there are lots of ways particle physicists do that too

Fair point. I guess they can just count the particles; or in a different situation the two alien space beings can just count the atoms in their lumps of "mass" of the same composition. And I'm sure they'd agree that those numbers had significance. Silly me.

Your other point, well, I guess "what really happens", ie: the result of experiment is the only test we have.

 

[trex1950]

The key to the why the photon can travel and be bent by gravity has nothing to do with it's mass. Because a photon has no mass. The answer is related to curvature to space-time due to light moving around an massive object. It is just following the curvature of space-time produced by the mass of a planet or star. It does not have any force, pressure, or gravity.

 

[Nano-Passion]

The key to the why the photon can travel and be bent by gravity has nothing to do with it's mass. Because a photon has no mass. The answer is related to curvature to space-time due to light moving around an massive object. It is just following the curvature of space-time produced by the mass of a planet or star. It does not have any force, pressure, or gravity.

You just bumped a 5 year old thread.

Doesn't photon get bent through space due to the electrical forces acted upon it?

 

[kirtg]

doesn't the kinetic energy of a photon give it a "mass" if energy=mass and mass=energy?

 

[kirtg]

if a photon is massless like the neutrino and has not charge like the neutrino, why doesn't it penetrate matter like the neutrino?

 

[Spourk]

if a photon is massless like the neutrino and has not charge like the neutrino, why doesn't it penetrate matter like the neutrino?

Neutrinos have mass.

 

[kirtg]

So if a nearly massless neutrino with no charge can penetrate matter with little likelihood of a collision, why doesn't a photon do the same thing"

 

[Matterwave]

The photon interacts with charged particles (like the electrons in atoms) via QED (EM forces basically). Neutrinos only interact with particles via the weak force.

Photons do not have rest mass.

In general, it's better to read the faq if you have some basic misunderstandings. If you can't find the answer in the faq or a quick search, then post a new thread, don't bump a ~decade old thread (holy crap PF is ~decade old!?).