Jacques

More precisely void of kinetic energy. Can you explain why ? Thanks

Temperature is the mesurement of the average speed of the molecules or atoms. Going down to 0K you slow down the molecules or atoms. At 0K mass won't be destroyed, will only get a bunch of molecules or atoms sitting there without any speed.

Gravity is not involve in that problem. Something with mass x and speed v hitting something else with mass y and speed 0 will always give the same impact no matter if it is on the moon or on earth or in space. You must know the difference between mass and weight to understand that.

Sorry to bother you with that, but does the math and equations in this paper are right ??? http://arxiv.org/ftp/quant-ph/papers/0204/0204037.pdf Thanks in advance

Thanks for your answers and for the links! These anilation processes are more complex than I thaught.

It is well known that the electron positron anhilation reaction give two photons. I was wondering what was the result of the proton/antiproton anhilation ? Since the proton and the antiproton are made of 3 quark each doesn't the proton/antiproton should give 6 photons (2 for each quark/antiquark) ??? Thanks for your answers.

I did a little search on internet to see if there are other peoples who thaught that electron, positron and other particle are in fact spinning photon and I found that paper: http://arxiv.org/ftp/quant-ph/papers/0204/0204037.pdf A lot of equations and it look very serious and with my little math base I feel that the guy knows what he is speaking about. Maybe some of you who knows a lot about QM can take a look and tell me if my feeling is right... I also found that http://forum.physorg.com/index.php?showtopic=1030

I understand the mistake I made... Looking at the force involved, it is easier for me to see that the conveyer belt will not be able to bring back the plane to a rest position. So the condition in the original post can never be met unless you put the brake on the plane...

I used circular orbit with average radius. I used pi=3.14 Maybe if try with more precisse value... Me too I saw that in an islamic site

Mean distance: 384,400 km Asuming circular orbit and pi=3.14 384,400*2*pi * 12,000 => 28 968 384 000 km 28 968 384 000 km/day= 335 282 km/sec That is in the order of speed of light Using Lunar Month = 29.53059 days [synodic relative to sun] .95 km/sec

Me too I don't see how it could lift. Unless the propeller is big enought and the engine powerfull enought to create a large airflow on the wing. But nothing like that stated in the initial post.

Meir Achuz Thanks for your answer. My question was about EM in air or in vacuum but it nice to know that in some condition a phase shift can exist. navynuke you are right we need something to induce a phaseshift so let me tell you what thought lead me to that question. In the electron/positron creation pair process, how does two gamma photon convert to matter ? What happen in the collision of the photon ? One of my thought was that in the collision the photons started to spin on itself giving the electron and positron pair. Momentum of the photons transformed in angular mometum... Matter would be spinning EM. How can this be possible ? Maybe the electric and magnetic field of the photons intefere and created a phaseshift during the collision. sin x + cos y =1 give a circle... That's just some thought. Does that model (spinning photon) or something similar been studied ? Is it theoritically possible ? Does the wave equation of a photon of .511Mev look like the wave equation of an electron ?? I am not an expert in physic and a not to good mathematician, that's why I am asking here. Waiting for your comment, proff or thought. Thanks

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The electric field is perpendicular to the magnetic field in EM. Electromagnetic radiation What I am asking for is a phase shift between the E and M field. Normally in a EM the max electric field is at the same time as the max magnetic field. They are in phase. Is it possible to modify that phase ? For example 90 degree: The electric field is max when the magnetic field is min... Photon are influence by magnetic field. I know that it influence the polarization of the photon. Does magnetic field modify the direction of photon ?

Hi In an other thread, it was told that the electric field is in phase with the magnetic field in EM waves (photon). My question is: Is it possible (theoreticaly or in practice) to shift the magnetic field 90 degree of the electric field ? If yes what would be the result ? Would it produce a rotation of the photon ? Thanks in advance for your answers.

Thanks again for your answers they are very clear! A last question: Is it true that one photon of more than 1.022MeV can spontaneously convert into an electron-positron pair ?

I just found that site: http://particleadventure.org/particleadventure/index.html I think that it might interest some people here;)

Let say we use .7MeV photons in a magnetic field so they separate quickly. I was woundering if the angle between the 2 photons influence the pair creation rate. Let 2 photons travelling in the same direction have 0 degre angle. At 0 degree my guess is that the production would be very low. At 90 degree I don't know if it's possible At 180 degree (photons going in opposite direction) my guess is that it would be maximum. So is there experiments been carried to mesure the rate of creation in function of the angle ? Thanks for your answers!

Do you mean that I can collide two photons of 0.511MeV to produce an electron positron pair ?

Depend on the photon frequency I am not sure but I think UV photon won't go throught glass

So it is theorically possible, but was never observe. Why should we wait for giant collider. Can't we produce gamma ray with enought energy by other way ? It's hard to imagine a photon collision: most of the time they pass throught each other... Anyway photon being it's own anti particle it would be the same mechanism as the electron anti-electron anihilation.

Thanks for your answer. What is the k vector ? Energy depend on the frequency momentum depend on the energy So only the frequency is necessary to describe energy and momentum ??? You lost me with "mode of the cavity" What cavity are talking about ? Is polarization related to spin ? What is "spin projection" Is angular momentum the same thing as spin ? Thanks again for your time.

I readed that pair creation is stimulated when the gamma photon pass by an heavy atom nucleus. Is there other conditions that will stimulate the gamma photon to create pair ? To create a pair the gamma photon need to have more energy than the equivalent mass of 2 electrons. Is it possible to combine 2 gamma photon each having the equivalent energy of 1.5 electron, to create a pair ? Thanks

Hi I have a simple question What are the quantum number needed to completly describe a photon ? Can we assing a vector to the direction of a free photon (a photon not yet detected) ? The one I know are the frequency, the momentum (not sure they are quantum number) Thanks

wave/particle duality Can't it be the vibration of the particle ??? Or can it be that particle don't exist as a point but exist only as a standing wave ???