Jacques

What about the crazy idea that the supernovae remanant is at the center of the sun. The material of the supernovae is ejected and collide with the interstallar gas and slowdown and after a while start to fall back to the remanent and reform a new star. (By the way supernovae doesnot always fly away Look at the Cassiopea or the Crab nebula)

I imagine that the earth is tracing an helix around the galaxy

I don't think that the molecule necesserly slow down. For example take a cylinder with a wall in the centre. One side of the wall is filled with air at ambient temperature and pressure and the other side is empty. Remove the wall (there is no receding wall). The pressure is now half the ambient pressure and the volume is doubled. From PV=nrT, T should be the same.

In Europe last night they had a LUNAR OCCULTATION OF VENUS Take a look at today's spaceweather.com/ site (December 2nd) for more info. There will be an other lunar occultation of venus visible from north america on 22 Apr 09 http://www.lunar-occultations.com/iota/planets/0422venus.htm That's a very nice sight !

Martin correct me if I mistake but, you can not use gravity sligshot to go outside the solar system.

OK I understand your problematic. I found that Depth of field calculator that can help you estimate the depth of field. Faster shutter speed is great when you increase magnification. Small motion appear bigger. I did some shut with my scope coupled with an old reflex Minolta 101. cable release is essential like you said. I tried the trick of the hat for longer exposure (1 sec &+) In a dark site focus the object, put your hat in front of the objective to block all light going in the scope without toutching the scope, press the release button block it open, wait for the vibration to stop... remove the hat for the time of the exposure, put back the hat in front of the objective, close camera shutter.

Hi nice pictures ! Yes it give depper field, but for astronomical images you don't need need deep field, just adjust the focus at infinity, and try to get the smalless f ratio. Higher apperture will give less definition. I was surprised when I saw that photo : It was on Space weather site

Hi I am searching for a free electromagnetic simulator or some library that I could use to compute the electromagnetic force on charged particles. It should be able to compute particle-particle electromagnetic interactions in a fixed electromagnetic field. If there are no free one, can you give me some commercial one that you know of. Thanks

What if the astronaute is comming back to earth ? Relativity time dilatation + blue shift = ??? Maybe he would sound normal .

Thanks NeonBlack for your calculations, but what you computed isn't it the force of a moving charge with repect to a non-moving charge (S frame vs S' frame) ? In the problem the charges are not moving relative to each-other...

Pete thanks for your answers, I went on your site and was not sure about the first sentence: I thaught that wire carrying electricity where charged. If I touch a wire I will get socked The negative charge are moving at v , to get L- maybe we need to apply Lorentz contraction to L ? That would leave a negative charge to the wire... Anyway I am sure that you know your physic better than me, but if you could explain where is my mistake it will help me. Neonblack Do you have references where I can see how you did the calculation ?

Thanks for your answers! Ok it is impossible that for two moving charges, the pinch force overcomes the electrostatic repulsion (no matter can go at c), but the pinch force goes agains the repulsion, so it is substracted from the electrostatic force. So the paradox still apply. One observer will see the same charges separating at a different rate... That doesn't explain the phenomena. Positive charge moving in the opposite direction in both conductor will also repel. The explaination I learned is that a wire generate a magnetic field around it, and the magnetic around each a wire are attracted by the magnetic field of the other. NeonBlack did you used the relativistic form of Maxwell's equations to calculate the speed at which the pinch force overcomes the electrostatic repulsion ? For bare charge, I am not 100% sure but I think that the pinch effect is used in particle accelerator to keep the beam collimated. I don't know if the effect is enought to overcome the electro static repulsion ?

May be someone else can answer that question ?

Yes and that's why I thaught of the second experiment An observer with a relative velocity will see the charges getting closer to each other, but a second observer without relative velocity will see the charge getting farther away from each other... Can you see the paradox I see ?

Hi I was thinking of two experiments and I cannot figure what would be the results. The experiment are done in a vacuum isolated from any outside electric or magnetic field. A moving charge will generate a magnetic field (it will move the needle of a compas), but if I follow that charge I will not be able to detect a magnetic field. Does the magnetic field exist or not ? The second experiment is 2 equal charge q1 and q2 are moving in the same direction with speed v. If v is greater than a value, I will see the distance between the charge decreasing because of the z-pinch effect. But if I move in the same direction and speed what will I see ?

When you create a vacuum in a vessel, there always some atoms and molecules left. The ionization of these atoms will give some ions. The ionization process I was thinking of first is something like in the Farnsworth–Hirsch Fusor Were you able to see the simulation ?

Sorry I don't understand your question... What is a thermal bath ?

Hi I post here under speculation so no body will move it here, but feel free to move it elsewhere if you think the idea have some value. I always been interested to the promises of fusion. Cheap clean energy, but the progres are slow and I am not conviced that the ITER project will give what is expected. The preceding developments of the tokamak design hited many wall, because of instability in the plasma at the high temperatures and intense magnetic field needed. So I started looking at alternative desing to produce fusion, wiki gives a good overview of these research. I found the Farnsworth–Hirsch Fusor idea interesting by it simplicity. No big magnet to draw the current. Just the energy needed to accelerate the ion to the necessary level for fussion to occur. The main draw back for further developpement of the idea was the grid errosion. I thaught of a system that would avoid that. To clarify my ideas I asked some question on that thread Electrostatic oscillator I found a simple simulation program writen in java and did some little modifications to illutrate my idea. I installed the modified 3D- electrostatic simulator here select "charged ring pair" in the first field selection and "Display: Particles (force). It is late now for me, then I let you take a look and I will explain more tomoro:D I don't know if some of you saw the focus at the center ? Each particle follow an 8 shaped orbit around the center. That is where the velocity is maximal and the density also and where, I guess, most of the fusion would occur. Also I imagine that supperposing a frequency in the voltage could create some increase in the density: the slower orbit will gain energy and the higer orbit will lose energy, but that is very speculative. It is a crude simulation and in real life many things can disrupt the particles orbits. In real life the particles would be deuterium and tritium or any other fussionable material like p-B. There will also be electron in the appartus and neutral atoms. In the simlation the particle are already charged and diistributed randomly in the space. In real life the ion would be created near the interior surface of the vacuum chamber. On there way to the center they will collide with neutral atoms and lose some energy and/or being deflected and/or ionized... Very complicated system will follow , but maybe after a moment the gas will become completly ionized....? I asked myself the question: Can I simplify the system more ?

Hi Norman I found that little article that is related to your work. How Long Is a Photon? Hope it help...

Do you have any references ? Always thaught that it was Darwin Wiki say Darwin....

Galaxy cluster are gravitationnaly bounded, and Andromede is part of the local group cluster.

Thanks again! I asking these questions because I want to know the best method to get H+ ion. What I mean by best is : The most efficent (the portion of the energy that is put in the system, that is used to create ion) The purest ion (ion without the electron being around ready to recombine) The bigest volume ( being able to produce a lot of ion) The most mono-energitic (ion having a small energy distribution) Maybe I should have ask the question directly, but I needed some understanding of the ionization process.

I found that link where you have the basic for Safe solar Viewing

Why is it a glitch if it come from wiki ?

Thanks Swansont That was the way I was thinking of calculating it, but I know that in neon sign they use voltage in the kV range and the distance between the electrode can be several meters. Neon ionization energy is 21.6 eV... My guess is that it is not field ionization that occur in a neon sign. Here is a link where I found lot of information about ionization mass-spectrometry Click on ion source in the left pane