there's something that's been bothering me for a while... if mass equals energy anf photon is made of energy, why scientists say photons do not have mass? maybe i missed something...
Lua, Scientists don't know what the hell they're talking about. Photons do have mass. That's why they curve when they pass large masses(like stars). Note to everyone: Spare me the Einstein curved-space crap theory. Tom
tom, they say neutrines (i don't know how to spell it sorry, english is no my first language) don't have either. was that proven (that does have mass)? why? in what do you base that?
Scientists don't know what the hell they're talking about. Photons do have mass. That's why they curve when they pass large masses (like stars). This should be good. Could you please explain to Lua how a photon *with* mass can be 'at rest?' How does a photon *with* mass experience acceleration? Does other mass increase when it's bombarded with photons? Note to everyone: Spare me the Einstein curved-space crap theory. Absolutely. We'd rather hear your explanation.
Joeblow93132 generalized: From this statement are we to feel compelled to conclude that, arising from your own innate appreciation for peer review, your own peers have encouraged you to consider yourself to be an authority on what Scientists actually talk about? What should be our motivation for sparing you from your own confusion if not to properly frame your own perspective with some attendant sense of personal gravity? Please Register or Log in to view the hidden image!
Mass is not the same as energy. Photons have energy but no mass. Joeblow: Some evidence to support your views would be nice. Please explain exactly why you think general relativity is flawed, and how we could experimentally show this. Also, please outline your own preferred explanation, and how we can test that.
[QUOTE Mass is not the same as energy. Photons have energy but no mass[/QUOTE] what about einstein's theory?
I'm a complete beginner in this stuff, but... I have never agreed with the "space is curved" stuff. And photons, as far as I can tell, were orginally thought of as not particles but as a measurement unit of electromagnetic energy. And to me, everything I have studied so far of EM waves and all that stuff says to me that we are there is more than one thing going on. On the one hand, particles are moving about. They stream through space from powerful sources, they pop out ofa heated wire, et cetera. On the other hand, particles move in response to motions of energy. If you look at the basic way particles move in a wave, it looks like they are bits of cork on an ocean wave, being pushed in various directions not by each other but by some fundamental energy (maybe I'm referring to what some have called the "plenum"). Seems to me we have detected the corks but not the ocean. Anyway, photons (in other words EM waves, whether the ocean or the corks, measured in units called photons) move in paths which are affected by gravity. That seems to indicate to me that either they have mass, or the ocean and gravity interact just as two magnetic fields will interact; whether corks or ocean, obviously there is interaction. However, that curvature of the paths of travel does not indicate that space is curved. It only indicates that the paths are being affected. Well, that's how it seems to me.
Lua, As you can tell from the reactions to my comments, most people on this board, and probably most scientists, believe that photons have no rest mass. When they are faced with the question of why the paths of photons curve when passing by massive objects, the say "Well, Einstein says that space is curved around large objects, so the path of photons will curve even though the don't have mass". I, on the other hand, don't believe that space gets curved because atractive forces also exist in magnetic and electric fields, and these fields can't be explained by the "curved space" theory. Therefore, if you assume that space is not curved, then photons have to have mass or they would always travel in straight lines. Neutrino's, if I am correct, are thought to be expelled at high speeds, and since they don't react with regular matter, they continue to move at these speeds.(The neutrino was never really proven to exist, it is probably just a theoretical particle that a scientist made up so that his equations would balance out) Q, "Could you please explain to Lua how a photon *with* mass can be 'at rest?' How does a photon *with* mass experience acceleration? " Easy. A photon has mass and a gravitational field. But unlike normal matter, the gravitational field of a photon is BIPOLAR. This would explain why photons accelerate to light speed, and travel at lightspeed. This would also explain why their paths bend when they pass massive objects. James R, "Some evidence to support your views would be nice. Please explain exactly why you think general relativity is flawed, and how we could experimentally show this. Also, please outline your own preferred explanation, and how we can test that." First of all, I have a theory but I don't have the resources to prove it(at least not yet). I believe that gravity is the result of COLLAPSING or CONSOLIDATING space between to massive objects. This is a brief discription: The gravitational field of an object is space with higher or lower amounts of energy(quants). The space closest to a large object has the most energy(gravity), and the energy becomes less as you move away from the object. When two fragment of space(with certain energies) meet, they're energies merge and the become one fragment of space. Since where there were two fragments of space, there is now only one, the objects move closer since the space between them is actually dissapearing. I would like to give an even more detailed explanation, but I have to get back to work. Tom
The path of photons being curved does not necessarily mean they have mass, I think (again, as you all know, I am a beginner at all this). I don't know, does magnetic force have mass? There is curvature and interaction there...
As you can tell from the reactions to my comments, most people on this board, and probably most scientists, believe that photons have no rest mass. Photons DO NOT have rests mass. I, on the other hand, don't believe that space gets curved because atractive forces also exist in magnetic and electric fields, and these fields can't be explained by the "curved space" theory. You're talking apples and oranges. EM fields have nothing to do with gravity. Therefore, if you assume that space is not curved, then photons have to have mass or they would always travel in straight lines. Photons DO travel in a straight line. This would explain why photons accelerate to light speed, Photons DO NOT accelerate. the gravitational field of a photon is BIPOLAR. Photons DO NOT have a charge. Lua, it is clear Joeblow does not know what he's talking about. But before you're given the proper responses to your queries, I'd like to hear more about Joeblow theories. It gets better all the time. Please Register or Log in to view the hidden image!
Photons travel in straight lines? Doesn't gravitational lensing clearly disprove that? And in fact any old refraction? Don't go calling me dumb, just explain it to me please. I'm still learning this.
Q, If you wan't to try to show off in front of Lau, please don't do it on my expense. Now to correct you're errors: "Photons DO NOT have rests mass" Did you put one on a scale or is this just a guess? "You're talking apples and oranges. EM fields have nothing to do with gravity." Really!!!You should tell that all the people working on the Unified Theory. You can save them alot of time!! "Photons DO travel in a straight line." As Adam pointed out, did you ever hear of a gravitational lens?? Have you looked through a telescope lately? "Photons DO NOT accelerate." What about when they pass from a dense medium like glass to a less dense medium like air?? Don't they accelerate to c?? "Photons DO NOT have a charge." I don't recall saying that they did. Maybe it's you who doesn't know what you're talking about?? Tom
Hi all, Adam: When saying that photons do travel in straight lines, you have to know that we're measuring in a very special way here. Your remark on gravitational lensing is entirely correct: in our three-dimensional world, photons do NOT necessarily travel in straight lines. However, if you start looking in a four-dimensional curved spacetime and use a special "ruler" to measure everything, then they happen to travel straight on. This ruler is called a "metric" in mathematical terms; in our daily world we are accustomed to the Euclidian metric: a straight line is what we expect it to be intuitively (a "line"). In curved spacetime, we use what is called the Riemann metric - this way of "measuring" distances immediatelly takes all the necessary physical effects into account. Photons travel in a straight line in a Riemann sense. Joeblow, Please take your time to write down a detailled description. It sounds very interesting indeed, but at the first sight there seem to be some striking similarities with the conventional law of gravity (expressed in energy terms). However, feel free to elaborate. Lua, Neutrino's have been proven to have mass. Check out the results on the Superkamiokande detector in Japan (a google search should do the trick). Also, energy does not always equal mass; the formula E = mc<sup>2</sup> you are referring to is only valid if the object you are studying is at rest. For moving objects (such as photons) the full formula reads: E<sup>2</sup> = (m<sub>0</sub>c<sup>2</sup>)<sup>2</sup> + (pc)<sup>2</sup> Here m<sub>0</sub> denotes the rest mass, p the momentum. Substituting m<sub>0</sub> = 0 in this formula yields: E = pc Or: for a photon the energy is contained completely in its momentum. I should add that for photons the momentum p is not the classical formula p = mv Please Register or Log in to view the hidden image!. Bye! Crisp
Crisp, Some day I will post a detailed explanation as a new thread. I still haven't worked it out completely(Still trying to unify the electric and magnetic fields into the theory). It's basically a math problem. Here is what I believe so far: 1. Electric, magnetic, and gravitational fields are not caused by particles traveling at light speed(except photons created by electromagnetic fields). They are stationary and can be considered as part of the particle. They are only a less dense part of the particle that matter can pass through. 2. The three fields to not stop suddenly, instead they get weaker as you move away from the particles. This could be because the fragments of space can only hold energy in multiples of a certain number. As an example, if the multiple is two then the energy values of fragments of space would be 1,2,4,8,16,32, etc. If you had an even number, like 64, the specific field would not exist(it would exist but it would be concentrated in the center of the particle). But if a particle had an uneven number like 63, it would break into 32,16,8,4,2,and 1, in other words, a field would be created that extends beyond the surface of the particle. 3. The most stable fragment of space would be the one with the most energy(taken into account it must be a multiple of a certain number). Example, as explained above, 64 would be more stable than 32. 32 would be more stable than 16, etc. Therefore, when a fragment of space from one mass, with the gravitational value of 4, met another fragment of space from another mass, also with a gravitational value of 4, they would create one fragment of space with a gravitational value of 8. This would cause the two masses to move closer because where there were two fragments of space, now there is only one. This happening to billions of particles at the same time could explain the attraction forces in gravitational, magnetic, and electric fields.(Unfortunatly, I still can't explain the repulsive forces). That's all for now. I'm getting tired. Any feedback would be apreciated. Tom
Cest moi You're talking apples and oranges. EM fields have nothing to do with gravity. " proof this Good catch. My bad. EM fields DO have something to do with gravity. I hastily and incorrectly worded my response. I was using the statement in context with the statement made by Joeblow. I will now consider my wrist, slapped. Thanks for that. Please Register or Log in to view the hidden image! Electromagntic radiation is basically light or photons moving at the speed of light carrying some energy. The difference between a radio wave and a gamma wave is the amount of energy they carry. They DO NOT carry a mass. GR says that anything that carries energy, momentum and stresses is a SOURCE of a gravitational field, that is, a curvature of spacetime. Therefore it is the SOURCE of the EM field that distorts spacetime by virtue of it's matter. Magnets, for example, are manifestations of certain types of matter, and carry energy. Therefore they will have a gravitational field and will distort spacetime. Because an electromagnetic field contains energy, momentum, and so on, it will produce a gravitational field of its own. This gravitational field is in addition and is infinitesimally small to that produced by the matter of the magnet. Adam Photons travel in straight lines? Doesn't gravitational lensing clearly disprove that? And in fact any old refraction? That is correct. Photons travel in straight lines. To understand curvature of spacetime is to understand the notion of a manifold. A manifold is basically a curved space, which, in small enough regions, looks like flat space. For example, the Earth looks flat from our ground dwelling perspective because we only see a tiny part of it, even though it is round. The photon moves along a geodesic which is the shortest distance between two points. The curved manifold of space will therefore make the geodesic appear curved. The photon will therefore move along a geodesic (shortest distance) that has been curved by a massive object. Gravitational lensing works under the same principles. Look up Riemann tensor and geodesic equation for the math.
"Photons DO NOT have rests mass" Did you put one on a scale or is this just a guess? Light is composed of photons so we could ask if the photon has mass. The answer is then definitely "no": The photon is a massless particle. According to theory it has energy and momentum but no mass and this is confirmed by experiment to within strict limits. Even before it was known that light is composed of photons it was known that light carries momentum and will exert a pressure on a surface. This is not evidence that it has mass since momentum can exist without mass. http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html "You're talking apples and oranges. EM fields have nothing to do with gravity." Really!!!You should tell that all the people working on the Unified Theory. You can save them alot of time!! "Photons DO travel in a straight line." As Adam pointed out, did you ever hear of a gravitational lens?? Have you looked through a telescope lately? Answers are in above post and in General Relativity. "Photons DO NOT accelerate." What about when they pass from a dense medium like glass to a less dense medium like air?? Don't they accelerate to c?? No. Photons NEVER accelerate. They are propagated instantaneously at 'c'. A photon is simply energy released from an electron that has a change in its energy state. An electron will increase its energy state when it absorbs a photon and decrease its energy state when it releases the photon. "Photons DO NOT have a charge." I don't recall saying that they did. No. You inferred it with your statement: the gravitational field of a photon is BIPOLAR
