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If plasma is just ions, why are they considered as one of the fundamental matter. Since plasma is visible, are they just electromagnetic radiation?

If light is emitted due to the energy level changes in electrons, can we say that electrons are source of light. When photons get emitted due to energy level changes in electrons, does the energy of the electrons get reduced? What is the reason why photons get emitted?   

Also in LHC, I read that they use proton collision to study fundamental particles, why they don't use electrons or other particles.

Can you please clarify.

Thank you very much.


That's a lot of questions at once, so let me start at the top.  

Plasma is a fundamental state of matter, because electrons are separated from their atoms the bulk of the time.  The plasma itself is still neutral.  It's different than a gas, where the individual atoms are mainly neutral.  Plasmas do emit electromagnetic radiation, but are not composed of it.

Light is emitted in may ways involving the acceleration of charged particles.  Electrons alone are not the only source of light, though they are the primary source (being the lowest-mass charged particle) in our everyday universe.  Photon emission is a complex subject beyond the scope of this forum at the level you're asking for answers.

At the LHC, they use protons because they're plentiful and have large masses which can be accelerated to extreme energies without destroying them.  Electrons are used at accelerators like SLAC (Stanford Linear Accelerator), but in circular accelerators they lose too much energy when they make bends in photon emission to be useful.  At other accelerators, like RHIC, other particles still are used.  So it's not just protons.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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