Jacques

velocity of the photon vx=c Can we move into the reference frame of the photon ? The gamma factor is 1/0. The Lorentz transform doesn't work. Lenght is contracted to zero. I understood that the equation apply to reference frame with speed below c Thanks for your answer again. I found a cool site on relativity lot of gif 4D rotating cube !!! Cool relativity!

Lorentz wrote the Lorentz transform. E/c,px,py,pz Does that 4-vec describe completely a photon ??? In relativity the fourth dimension is a dimension of time ??? Is E/c the time component or momentum is an other story ? A photon move at c on x, px must be 0 under Lorentz lenght contraction ?? Thanks for your answers. I don't want to abuse on your time. It seam so clear for you! Trying to imagine a photon I try to move in its reference frame . Length contraction eliminate the x spacial axis or maybe leave a plank length. All the length of the universe contracted to epsilon... That leave the y and z spacial dimension (maybe occupied by the electric and the magnetic field. A photon is a Flatlander ! The clock is stopped. Nothing happen. Back in our frame can we mesure the lenght of a photon ? Would it be a good analogy to figure the photon as a soliton ?

It depend on what you base your criteria of simultaneite What is now ? Is it universal or local ? You can in imagination put yourself halfway between here an Andromeda an say the supernova in the Milkyway exploded at the same time as that one in Andromeda. The succesion of frame that you describe is exactly what is happening we are running throught space around the sun around the galaxie and what else. Globally on earth we all move in the same direction across space and time that is why we feel a universal now. Take a jump in the air and you just changed your frame stack. Why 3 ? I start from the principle that the only thing that exist is motion. Without motion nothing would happen. Space or time wouldn't exist . Motion is space over time v=s/t. v is a 3 vector. Space and time are different aspect of the same entity: motion v. We usualy represent v as an arrow pointing in space but it also point in time. That's my thinking that I tried express here. Does it make sense to you ? I know that some fringe scientist who seem to know alot a bout relativity think that time maight be more than one dimensional. Excuse my english I don't have my dictionary and I am not sure about the spelling of some word.

Because like you said : OK I will try to understand the four-vector is invariant under Lorentz transform. Explain how E=pc was found ? four-vector is p in the E=pc invariant = two length are the same Lorentz transform: used to change reference frame.( Imply relative motion ) E can be seen as the kinetic energy an electron would acquire when hit by a photon. The relative velocity of the photon and the electron is c. I don't see how the Lorentz transform apply . Is it Einstein who found that equation ? When he was working on the photo-electric effect ? Thanks for you answers.

Hi I tried a couple of time to discuss of the possibility that time have more than 1 dimension and it look like physicist doesn't like that idea. Why ? My thought is that time is 3 dimensional. According to relativity there is no absolute time. Time flow differently depending of relative velocity. 'Now' for me is not the same as the 'now' for an Andromedian; there is a time distance of 2 millions years. If I take an other galaxy I will find an other time distance and if I want to compute the time distance from Andromeda and the other galaxy I will need to do some 3D geometric calculation. If you bring that back to earth scale the distances are very small: from tenth of seconds to nano seconds and smaller. For me every location in space has its own location in time. My 'now' is not the same as your 'now'. An other thaught in string theory we speek of up to 21 dimension of space! Why does physicist doesn't hesitate to add spatial dimensions, but doesn't want to add time dimension ??? Thanks

Yes very simple to derive, but how this equation ([math] E^2 = m^2 c^4 + p^2 c^2 [/math]) was found ?

YT2095 Think of the photo-electric effect. Photon have no mass. Does that equation come from photo-electric effect mesurement or is it derived from theory ?

Simpler in what sense ? electron-positron system must be very hard to create: create a positron, bring it to the velocity and good distance to an electron... Maybe simpler mathematicaly

I thaught that was the question: why no sound or heat.? I didn't see it as a question about the 1000 pieces trajectory...

Can you explain a little more? The ground state in an ordinary atom keep the electron far from the nucleus. What difference is there with the electron-positron system ?

I understand the QM explaination but it bring me to an other question: Why doesn't an electron orbit a positron, instead of anilating each other ?

Does the results of the runs, been analysed like the autor of the paper, Reginald T. Cahill, say I think that to be consistent a calibration using the Loretz contration must be used to analyse the data. One thing in his paper that bug me is that he claim that in vacuum the result need to be null. Their are other experiments: ... who support absolute motion, does these experiments repeatable ? Does the arxiv.org a good reference for main stream science ? Or is it a freak, fringe or alternative... archives ? Where can I find reliable articles ? Or may be it doesn't exist

Physics, abstract physics/0508174, The Michelson and Morley 1887 Experiment and the Discovery of Absolute Motion wrote: http://arxiv.org/abs/physics/0508174 This is an article that claim that using lenght contraction to calibrate the Michelson and Morley instrument, the data prove absolute motion ! I am not an expert but it look to me very convincing. I would like to know what expert think of it. Thanks

That is what I think that we don't know which state it is but it have only one state Thanks for your answers. I was under the impression that physicist where realy thinking that it was in the 2 state at the same time. I think that some physicist mixup reality and mathematic

Then why doesn't the photons scattered ? If a photon is absorbed by an atom it can be reemitted in any direction, not necessarily in the same direction.

I know. How do you explain the change in speed of the light in a medium ? I was refering to some explainations given to that in this forum.

That's what I also think but I think that physicist say superposition is both state at the same time... Can a real physicist give is opinion on that ??

Yes completely confusing. Why test for a color I know will never happen ? The photon are polarised to the left or to the right. If I mesure one to be left, I am sure the other is rigth polarised. I think that the confusion come from the supposition that the photon before mesurement is in both state at the same time (left and rigth polarised) something I don't accept...

Hi I readed in many threads in this forum that the speed of light is constant even in a meium like water or glass. That the apparent slowing down is cause by the photons being absorbed by the atoms of the medium and after a moment being re-emitted. The speed of the photon between atom is always c. My question is Why doesn't the light is scattered, dispersed ? How does the atom remember from which direction the photon came ? Thanks For your answers

So what is mysterious about that ? I have a stick with one end painted in red and the other painted in blue. I have two box, I close my eyes, break the stick in two and put one piece in each box that I close. I send you one of the box and the other too an other person. When you will open the box and see that you received the blue end. Instantanly you will know that the other received the red end ! HUU fantastic that's magic

I readed in scientific american that something like 99% of the mass of the proton come from the rotational motion of its constituents quarks, that the mass of the quark are realy small. Can we extend that to the quark and tell that the mass of the quark are 99% motion of it constituent (I know that the standard model consider the quark fundamental) At the end can it be that the only real thing is motion ?

What readed for photon was about the polarisation. Entangled photon can be produced by shining an UV photon on a barium cristal leaving two photons having half the frequency of the incomming UV. Is it possible that the creation of entangled photon always create two photons of opposite polarisation ? It is not mesuring the polarisation of one photon that determine the polarisation of the other. They are always created with opposite polarisation.

Thanks for the link ! It will be a lot of work for me to understand, but with the help of Wikipedia I think I will be able to grasp the essentials things. My goal is not to do any calculations, but to understand the basic principle (more than the usual analogy).

Thanks Severian So the standard model can compute the life time (or should I say the half-life time ?) of the neutron! I asked because the only thing I saw on the standard model is little table with the "fundamental particle" and some Feynman diagram . What would be a good start to go deeper than that ? What level of math is necesary ? I completly agree and I am at that step.

I was wondering if the Standard Model was able to predict the instability of the neutron ? Is it able to predict 15 minutes life of the neutron ? If yes what are the equations and parameters used to achive that ?