Talk:Photon/Photons and Mass Debate2

message: I have issues with a specific statement...(and most of this article...)
"In some respects a photon acts as a particle, for instance when registered by the light sensitive device in a camera."
A massless "particle" could not possibly contain enough "information" to render color or even shading onto film.  Only a wave function could effect that.
Photons cannot be particles, simply because if they are without mass they would be nothing.  If they have mass, they violate the General Theory of Relativity.  If energy directly equals mass, as E=MC2 represents, then a photon must have mass as it is capable of doing work (read as having energy).  An item of mass that would be traveling at the speed of light would become infinitely massive, said Einstein, and we all know that our universe is not one infinitely massive photon.  The only solution for this quandry is to realize that photons do not exist.  Light is only a wave function.
I am going to take this one step further and invalidate almost all of the calculations made within this discussion thread.  As light is not a particle, and only a wave function carried through mass, light cannot travel through a true vacuum of relatively large volume.  C cannot be a constant, because it specifies that light has a set speed within a vacuum, but if light can't travel through a vacuum, then how can the constant be valid?  It can't be.  There are no human beings that can prove me wrong on this either, as there exists nowhere in the universe a true vacuum of relatively large volume.  (yes, there is true vacuum everywhere, as the space in between all singularities, but the distance between massive objects is still relatively small.  Massive objects meaning all items of mass, such as single atoms.) All of modern physics is built upon a theory that is not proven, or provable, but can be proven wrong.  Theories are not fact.  Facts are facts.  You cannot build fact using parts that are still only theories.
Kevin E. Carman  11-18-05
:Sorry, but you just don't know enough physics to make a cogent argument on this issue. Pretty much everything you are saying is incorrect, but I'm not going to spend the next two hours writing a detailed rebuttal. Go take a course in modern physics. 
:Clue: in modern notation E≠mc2, and mass does not increase with velocity (that would not work with General Relativity). Massless particles carry momentum and energy just fine.--Srleffler 08:06, 23 November 2005 (UTC)
replies: text:  You argue that photons can't be particles because they have no mass. Note that photons have relativistic mass but no rest mass. At the speeds that photons travel, one could conceivably think of them as a tiny particle (like a neutrino which was previously thought to be massless, but have been since found to have a rest mass). As long as the particle is moving, it exerts a gravitational field and has momentum - just like any mass would. The quote "light is massless" is thrown around too freely, and people who hear it most likely don't understand the difference between rest mass, and relativistic mass. Fresheneesz 22:40, 7 April 2006 (UTC)
thread_title:  Breaking some people's bubbles? 

message: I hesitate to write this after the section above, which frankly looks crankish to me, but there doesn't seem to be any other place to put it.
What is the status of the possibility that photons have nonzero rest mass? I remember seeing an old Scientific American article on it, showing how Maxwell's equations would have to change, among other things. As I understand it, current observations have put an upper bound on photon rest mass, but have not ruled out its existence. However, supposedly (I don't understand why), the discovery of a magnetic monopole would refute a nonzero rest mass for photons.
Anyone know anything about this? Have there been any theoretical or experimental developments that bear on the question since the article I remember (which probably would have been from the '70s or so)? --Trovatore 00:23, 23 November 2005 (UTC)
replies: text: I'm afraid I don't believe you know enough physics to give a useful answer to my question. For those who are interested, the question is discussed at Wikipedia:Reference desk/Science#photon mass. (I don't know how long the discussion will stay there or whether it will eventually be archived.) --Trovatore 19:17, 6 December 2005 (UTC)

text: Please enlighten us with your complete unified field theory.  Even better, you could submit it to a peer-reviewed scientific journal for publication.   Best of all would be to provide us with a citation of an existing article in such a journal where we can all read about it. -- ALoan (Talk) 20:07, 6 December 2005 (UTC)

text: I plan on publishing it.  I am currently writing it for exactly that.  Kevin Carman
The discussion at the reference desk has been archived at Wikipedia:Reference_desk_archive/Science/December_2005#photon_mass. Someone might like to incorporate the information from there into the article. --Trovatore 19:19, 2 January 2006 (UTC)
thread_title: Photon mass

message: *"Photons are deflected by a gravitational field twice as much as Newtonian mechanics predicts for a mass traveling at the speed of light."
Since this isn't getting answered in the above post, I'll reitterate this. This sentence doesn't make sense to me. How does Newtonian mechanics predict the deflection of light by gravity? And what "mass" is it talking about (since the article says light is massless)? Fresheneesz 19:37, 10 April 2006 (UTC)
replies: text: To reiterate the answer (posted above), Newtonian mechanics predicts a deflection that is independent of mass. (For a detailed derivation, see Newtonian gravitational deflection of light revisited.) In that sentence "mass" is being used figuratively to mean "test particle" (often called a "test mass" in gravitational contexts). -- Xerxes 20:04, 10 April 2006 (UTC)
replies: text:  Yea that link doesn't help. How can deflection of gravity be independent of mass - especially in newtonian physics? What *was* it dependent on? Fresheneesz 10:19, 20 April 2006 (UTC)
replies: text: Could you be more specific? What about the detailed derivation of the appropriate equations is not helpful? Note that the deflection does depend on the mass of the deflector, it just doesn't depend on the mass of the deflected object (the light, in this case). To be really perfectly fair, there ought to be a teeny-tiny correction due to the deflector being nudged by the gravity of the deflected object. Since the deflector is usually a star, it doesn't move very much. However, such a term would depend on the mass of the deflected object. -- Xerxes 14:24, 20 April 2006 (UTC)
replies: text: Ahh, I see, maybe you're right. I don't have time to read it again (I only skimmed it the first time), but i'll see if I can make sense from it. In any case, that part in this article isn't very clear since most people aren't familiar with newtonian bending of light. Is there a page on that on wikipedia? I'm going to red link "Newtonian mechanics predicts" for now. Fresheneesz 21:57, 20 April 2006 (UTC)
thread_title:  "...deflected by ..gravit[y] .. twice as much as Newtonian mechanics predicts..." 

message: People are *always* confused about the "masslessness" of light. Light does have the property of the outdated concept of relativistic mass. I want to write a little blurb - not on relativisitic mass (which everyone says is a bad concept) - but on the gravitational attraction and momentum of light. I would also like to mention the "effective mass" of light, which is derived from its gravitational attraction and momentum - like any other mass is. 
I don't think anyone can really understand light without knowing that *while moving* it acts like it has mass. I have a couple sources I could site to support this view:
Anyone like to give me the thumbs up? - Fresheneesz 06:28, 8 May 2006 (UTC)
replies: text: Absolutely not. "Acts like it has mass" is meaningless nonsense. Photons act exactly as if they have zero mass; they do have zero mass. -- Xerxes 15:17, 8 May 2006 (UTC)
replies: text:  Did you not read what I wrote? I was not talking about rest mass. The *only* way humans can detect somethings mass is through detction of momentum and gravity. Photons have both of these properties while in motion. Please read what I write if you're going to call it nonsense. Fresheneesz 01:36, 9 May 2006 (UTC)
replies: text: This is also nonsense. General relativity indicates that objects are deflected according to the geodesic equation for a metric determined by the stress-energy tensor. Mass is only a small part of the stress-energy tensor; gravity is due to many things other than mass. The way you actually determine mass is by the root squared difference between energy and momentum. -- Xerxes 16:18, 9 May 2006 (UTC)
replies: text:  What is a "root squared difference"? The bottom line is that photons have momentum and are effected by gravity, and that isn't addressed very well in this article. Like I have said before, there are millions of people that simply *do not* understand that photons can be "massless" *and* be effected by gravity, or push things. Fresheneesz 05:28, 10 May 2006 (UTC)
replies: text:  Root squared difference: m = \sqrt{E^2 - p^2}. I think the article is very clear that photons are affected by gravity. Associating that effect with mass only served to propagate a falsehood. -- Xerxes 16:50, 10 May 2006 (UTC)

text:  Do you deny that photons bouncing around in a box will make the box heavier than if it had no photons inside? Fresheneesz 05:28, 10 May 2006 (UTC)
replies: text:  While a box full of photons may have mass, a single photon does not. Since boxes of photons are not everyday sorts of objects, they are not mentioned in the article. See, for more detail, photon gravity on the topic of boxes of photons. -- Xerxes 16:50, 10 May 2006 (UTC)
replies: text: Of course you don't really need the box; two photons, not going in exactly the same direction, constitute a system having nonzero invariant mass. That seems like a fairly "everyday object" to me. I would think it might rate a mention here. --Trovatore 17:05, 10 May 2006 (UTC)
replies: text: It's interesting, but is it about photons? I'd say it's something that belongs in an article about mass or binding energy or some other relativistic phenomenon. I mean, you could say the same thing about a box of neutrinos (modulo neutrinos actually having a tiny mass). -- Xerxes 19:40, 10 May 2006 (UTC)
replies: text:  Neutrinos do have mass though, which makes anyone considering it be less than confused about why it interacts with gravitational fields etc the way it does. Photons are the *only* thing in science that most people have heard of that has no invarient mass. Given that it involves photons, it deserves at least a mention on this page, and like you said, probably on pages involving relativistic phenomenons, and articles about mass. People aren't going to read the entire wikipedia, so multiple mentions of the same thing should appear whereever relevant. And I think it is relevant in this case. Fresheneesz 10:34, 11 May 2006 (UTC)

text:  BTW, I like the link you gave - it says very nicely exactly what I was trying to say. Fresheneesz 10:35, 11 May 2006 (UTC)
thread_title:  Photons have relativistic mass - ie gravitational attraction and momentum 

message: I had writen that a single photon can't turn into a particle or particles with rest mass, for the reason that the energy of a single photon is not defined, it's rest mass is zero, and rest mass (invariant mass) is conserved in reactions. However, I neglected to mention that of course single photons can turn into particles with rest mass by interaction with another particle. In that case, it is because the photon provides an extra invariant mass to the system which IS defined. 
This is very much the same case as a single photon in the box, above. The photon and the box now defines a 2-object SYSTEM, in such a system has increased invariant mass due to the photon, and so the energy available from the photon to produce rest mass (in the form of other particles) is now defined. In the case of a photon interacting with a nucleus or other charged object in pair production, much the same thing happens. Since we have a system, the single photon's energy can be defined: if it's 1022 kev in the center of momentum frame of the 2-particle system, that's enough to make an electron-positron pair.  If it's less than that, it can't happen. That second particle is necessary not just to absorb the extra momentum when the photon offloads its energy, but also acts as an objective guage to how much "rest-mass convertable" energy the photon "has." Otherwise it's just a matter of observer. 
Single particles with rest mass can decay all by themselves, because they have some store of minimal energy which isn't kinetic. For a photon there's no such thing, so in a sense they all need "help" from an external reference to tell how much "kinetic" energy they have. Sbharris 22:41, 9 June 2006 (UTC)
replies: text: For a single photon... what you're saying here seems right.  For two photons, you *can* create particles with rest mass... it's done all the time at the B-factory here (this is my third edit to this section - I am finally satisfied with this link I provide here :D ). I know it may seem like fantasy that from two massless Bosons you can create positive-mass Leptons and Hadrons but it's done all the time.  At the PEPII B-factory (link above) the Upsilon "4S" resonance is exploited to do just this very thing.  I've added this photon article to my watchlist. I have experience in this and it has always been an interest of mine. I look forward to contributing to this article thus. Astrobayes 21:57, 26 June 2006 (UTC)
thread_title: Note about pair production

message: According to the article, photons have a rest mass of zero but have a small relativistic mass while they are moving.  There's just one thing I don't understand about that.  Hypothetically, if I were to somehow travel at the speed of light and then fly next to a photon, then relative to me, the photon would be at rest.  However, as stated earlier, photons have a rest mass of zero.  So, if I were to fly next to a photon, wouldn't it then blink out of existence?
:In a sense. If you fly in the same direction as a photon sufficiently fast, then you can redshift its energy down to the point where no reasonable detector in your frame can detect it. Melchoir 02:59, 29 July 2006 (UTC)
replies: text: It might be more correct to say that single photons in free flight have an undefined energy, since you can make their energy (or relativistic mass) anything you like, by choosing your inertial frame (you do that for particles, too-- for single particle the kinetic energy is anything you like, but zero only in ONE frame). But such a photon has no rest mass because it's never at rest. Only when you get two or more photons going in two or more different directions, do you get "stuck" with a minimal energy for the system, which will occur in just one of all possible frames, as with the single massive particle. This frame happens to be the frame in which the photons have no net momentum (it all cancels out). In that frame, they all have minimal energy, when you add it up. And THAT energy is their invariant mass, as a system. It's the energy in the system which is available to make massive particles with rest mass. But note that unless you have two or more photons, that energy doesn't appear. There is no way for nature to "decide" how much energy a single photon has available to make rest mass, unless it has a reference point frame (a second particle) to do it. And as soon as you choose that frame by introducing a second particle with rest mass at rest in that frame, you define the photon's energy FOR that frame, and thus define how much energy you have to work with, if it interacts with the second particle. For a system of two photons (where neither photon can be at rest, but both can be flying off in exactly opposite directions), it's the zero momentum frame (the center of momentum frame) which defines the minimal (rest) energy. I'm not sure that's clearSBHarris 03:25, 29 July 2006 (UTC)
thread_title:  Photons at rest mass