derek w Posted March 26, 2013 Author Share Posted March 26, 2013 (edited) No, that doesn't count. You have changed your reference frame when you do that; energy is not an invariant quantity. But my original question was do all photons have equal energy in 4 dimensional space-time? It's the 4 dimensional space that changes not the photon? Edited March 26, 2013 by derek w Link to comment Share on other sites More sharing options...
swansont Posted March 26, 2013 Share Posted March 26, 2013 But my original question was do all photons have equal energy in 4 dimensional space-time? It's the 4 dimensional space that changes not the photon? Space-time is already 4-dimensional. Photons do not all have equal energy. Link to comment Share on other sites More sharing options...
beefpatty Posted March 26, 2013 Share Posted March 26, 2013 Do you possibly mean 4 spatial dimensions and one time dimension? Link to comment Share on other sites More sharing options...
derek w Posted March 26, 2013 Author Share Posted March 26, 2013 (edited) Do you possibly mean 4 spatial dimensions and one time dimension? Yes,you have hit the nail on the head there. (w,x,y,z) + t r2 = w2 + x2 = wavelength/4 where r = radius and w = 0 is a point of equilibrium Edited March 26, 2013 by derek w Link to comment Share on other sites More sharing options...
beefpatty Posted March 26, 2013 Share Posted March 26, 2013 My gut reaction is that if the photon is entirely (or partially) polarized in the 4th space dimension we would notice some energy missing in our 3 dimensions. I'm not sure what your equation is supposed to represent, could you explain it further? Link to comment Share on other sites More sharing options...
swansont Posted March 26, 2013 Share Posted March 26, 2013 What radius? Link to comment Share on other sites More sharing options...
ACG52 Posted March 26, 2013 Share Posted March 26, 2013 In which way would a photon change it's momentum,it can't change it's velocity and it can't change it,s mass. It can change it's energy. Link to comment Share on other sites More sharing options...
juanrga Posted March 26, 2013 Share Posted March 26, 2013 (edited) In which way would a photon change it's momentum, For instance via Compton scattering, the photon changes its momentum [math]p_\gamma \to p_{\gamma'}[/math] due to collision with an electron at rest. The electron final momentum [math]p_{e^-}[/math] is the difference between the final and the initial momenta of the photon (the law of conservation of total momentum holds) [math]p_\gamma - p_{\gamma'} = p_{e^-}[/math] it can't change it's velocity and it can't change it,s mass. The Newtonian expression [math]p=mv[/math] is only valid for a massive free particle moving at non-relativistic speed. The photon is both massless and relativistic. For a photon [math]p_\gamma=h\omega/c[/math] with [math]\omega[/math] the frequency. Edited March 26, 2013 by juanrga Link to comment Share on other sites More sharing options...
derek w Posted March 29, 2013 Author Share Posted March 29, 2013 What radius? Question? does a photon go through a cycle of existence e.g:- from one point existing as an electron through a point of non-existence to a point of existence as a positron and then non-existence and back to electron? Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2013 Share Posted March 29, 2013 Question? does a photon go through a cycle of existence e.g:- from one point existing as an electron through a point of non-existence to a point of existence as a positron and then non-existence and back to electron? No Link to comment Share on other sites More sharing options...
derek w Posted March 29, 2013 Author Share Posted March 29, 2013 If I have 4 spacial dimensions(w,x,y,z) then an electron and positron can occupy the same position in 3 dimensions but different positions in 4 dimensions, (w-r,0,0,0) and (w+r,0,0,0) thereby have mass but no electric charge(a wimp/dark matter).only if the electron and positron oscillate on the x,y,or z axis,would they have a detectable charge.And only if they have enough kinetic energy would they separate. Link to comment Share on other sites More sharing options...
beefpatty Posted March 29, 2013 Share Posted March 29, 2013 I think I see where you're going with this. What makes the 4th spatial dimension special i.e., why is only an overlap in our three dimensions enough to cause annihilation? What happens if they overlap in all four dimensions? What determines a scattering event isn't the overlap in some the dimensions but the overlap in all of them, which is easily generalized to any number of spatial dimensions you want. If there were a fourth spatial dimension, then we would expect there to be collisions where a scattering event should have happened in our three dimensions but didn't because the particles missed each other in the fourth dimension. What I'm getting at is we should see cross sections that deviate from theory (namely that are lower than what theory predicts), which we don't. Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2013 Share Posted March 29, 2013 We don't observe this happening. The Pauli exclusion principle works in 3 spatial dimensions. Link to comment Share on other sites More sharing options...
derek w Posted March 29, 2013 Author Share Posted March 29, 2013 If 2 like charged particles are heading towards each other,the 2 particles radiate photons towards each other therefore pushing them apart,however if 2 opposite charged particles(electron/positron) are heading towards each other they must radiate photons outward until the electron and positron occupy the same space. We don't observe this happening. The Pauli exclusion principle works in 3 spatial dimensions. Does the pauli exclusion principle apply to electron and positron occupying the same space? Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2013 Share Posted March 29, 2013 No, it would apply to 2 electrons, but space doesn;t suddenly become 4D when a positron makes an appearance. Or are you claiming that it does? Link to comment Share on other sites More sharing options...
derek w Posted March 30, 2013 Author Share Posted March 30, 2013 Can mass be explained with 3 dimensions? Link to comment Share on other sites More sharing options...
elfmotat Posted March 30, 2013 Share Posted March 30, 2013 Can mass be explained with 3 dimensions? What do you mean by "explained?" Link to comment Share on other sites More sharing options...
derek w Posted March 30, 2013 Author Share Posted March 30, 2013 What do you mean by "explained?" modelled. Link to comment Share on other sites More sharing options...
ACG52 Posted March 30, 2013 Share Posted March 30, 2013 Substituting one vague word for another does not help. Link to comment Share on other sites More sharing options...
elfmotat Posted March 31, 2013 Share Posted March 31, 2013 modelled. This whole thread is very strange. Of course you can "model" mass in any number of dimensions. It's just a scalar. 1 Link to comment Share on other sites More sharing options...
derek w Posted April 5, 2013 Author Share Posted April 5, 2013 No, it would apply to 2 electrons, but space doesn;t suddenly become 4D when a positron makes an appearance. Or are you claiming that it does? The vacuum would be 3 dimensional,particles would be 4 dimensional ripples. Link to comment Share on other sites More sharing options...
swansont Posted April 5, 2013 Share Posted April 5, 2013 The vacuum would be 3 dimensional,particles would be 4 dimensional ripples. Then your hypothesis is proved wrong. Electrons obey Pauli exclusion in 3D. A fourth dimension would make them distinguishable, so they wouldn't have to obey it. i.e. a proposed fourth dimension carries with it the prediction that electrons wouldn't obey Pauli. They do. Back to the drawing board. Link to comment Share on other sites More sharing options...
elfmotat Posted April 5, 2013 Share Posted April 5, 2013 Then your hypothesis is proved wrong. Electrons obey Pauli exclusion in 3D. A fourth dimension would make them distinguishable, so they wouldn't have to obey it. i.e. a proposed fourth dimension carries with it the prediction that electrons wouldn't obey Pauli. They do. Back to the drawing board. Why would an additional dimension make electrons distinguishable? I can't think of any good reasons. Link to comment Share on other sites More sharing options...
Przemyslaw.Gruchala Posted April 5, 2013 Share Posted April 5, 2013 Then your hypothesis is proved wrong. Electrons obey Pauli exclusion in 3D. A fourth dimension would make them distinguishable, so they wouldn't have to obey it. i.e. a proposed fourth dimension carries with it the prediction that electrons wouldn't obey Pauli. They do. Back to the drawing board. Electrons have the same electric charge = same charged particles are repelling. Without any other reasons such as Pauli exclusion needed. Link to comment Share on other sites More sharing options...
swansont Posted April 5, 2013 Share Posted April 5, 2013 Why would an additional dimension make electrons distinguishable? I can't think of any good reasons. Exchangeable is a better word. You can't have two electrons in the same place, but if there was a fourth dimension, they could be separated by their fourth-dimensional coordinate. IOW their wave functions would not be identical in 4D, even though they were in 3D. Electrons have the same electric charge = same charged particles are repelling. Without any other reasons such as Pauli exclusion needed. Completely beside the point. Link to comment Share on other sites More sharing options...
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