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I Would protons in LHC lose energy over time if ejected out?

  1. Sep 11, 2015 #1
    I googled this and didn't find anything. But it's a simple question. If a proton was moving 99.999% the speed of light in the LHC, and the earth and LHC and everything around it disappeared, would the proton lose speed or energy overtime? assuming no background radiation etc.

    A simpler way of putting might be do the protons in the LHC lose energy or speed in some way and need to be kept up with magnets (not assuming rotational energy loss in LHC loops)?

    basically if a proton was moving 99.999% the speed of light in outer-space assuming no cosmic background radiation, it would obviously keep moving that speed forever assuming it wasn't affected by anything, but I'm wondering if a proton that's accelerated with a charge or a highly charged proton would lose speed or react differently?

    Last edited: Sep 11, 2015
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  3. Sep 11, 2015 #2


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    How the proton was accelerated is irrelevant. This is clear already in classical physics as it is essentially Newton's first law.
  4. Sep 11, 2015 #3
    it's probably wrong what i'm saying, but it seems like there should be a difference, i'm just trying to figure out if there's some difference, you put it more clearly than i did, it seems odd to me, time dilation, the faster two objects are moving relative to each other, the weaker their forces are, it's not the case with the LHC, the LHC is not relative to the protons

    but i still think there should be something different between accelerating something with momentum physically/gravitationally compared to accelerating something with a charge, i mean your answer is what i thinking i would get, but if anyone has any knowledge of differences please pm me or post it here assuming it isn't closed

    if there was a difference, how would we even know? we accelerate everything with a charge experimentally

    don't charges go perpendicular to one another, do all charges need to follow a circular path... then how would linear colliders work...
    Last edited: Sep 11, 2015
  5. Sep 11, 2015 #4


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    A difference to what?
    There is a reference frame where the protons are at rest. Do you expect them to accelerate in this frame - and if yes, in which direction? The arbitrary one that we on earth would call "slowing down"?

    There is a difference during the acceleration process, but afterwards the particles don't care what happened before.

    No, of course not. Free charges (as all free objects) travel in a straight line. The LHC uses powerful magnets to make the protons follow the beam pipe. That is limiting the energy of the protons - protons with a higher energy would need even stronger magnetic fields or a larger circumference to keep them.

    Acceleration is done with electric fields, magnetic fields do not increase the energy of the particles.

    Protons in the LHC lose some energy due to synchrotron radiation while they are flying through those magnets (which means the acceleration section cannot be switched off completely), but that is a different topic.

    I don't know what "rotational energy loss" is supposed to mean.
  6. Sep 11, 2015 #5
    huh? I'm just talking about comparing differences in the force of a protons charge compared to a proton that's been accelerated mechanically or electromagnetically

    like you said there may be a frame at which protons are at rest, but i doubt that protons and electrons, or anything which does not have enough internal rotation to cancel out the speed of light, could ever be at rest in an absolute frame, i could go on about that for a while

    well can you please go into that a little more... i guess what i'm thinking is that a proton accelerated mechanically or gravitationally wouldn't have such a strong attraction/repulsion to the magnets in the LHC as one accelerated electromagnetically, it's possible that a proton accelerated magnetically would lose its "difference" afterwards and the particles wouldn't care, i guess... or i'm just wrong which is likely

    "Protons in the LHC lose some energy due to synchrotron radiation" is that the difference you were referring to?

    i was trying to refer to the effect that electrons have when they release photons when rotating in colliders or something... just ignore it

    i was kind of asking that question because of this and how magnetic fields work

    would an electron follow a spiral path in a linear particle accelerator? could you accelerate something to near the speed of light in a straight line? it's not really an important question
    Last edited: Sep 11, 2015
  7. Sep 11, 2015 #6


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    This doesn't make any sense. The speed of light is just a velocity. A number. It's not something that can be canceled out.

    First of all, 'mechanical' acceleration is electromagnetic acceleration. The same forces are at work in both cases.
    Second, you are indeed incorrect. Particles do not care how they are accelerated. They do not lose their charge or any other property if accelerated a certain way.
  8. Sep 11, 2015 #7
    yeah i know that... i'm talking about the electromagnetic force with charged particles only, i would actually suggest that mechanical movement is strong nuclear force or something. it's certainly not a distance/squared equation the way gravity and the electromagnetic forces are
  9. Sep 11, 2015 #8


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    It is not a nuclear force. The force exerted between you and your chair is due to the repulsion of electrons in the atoms and molecules. At very large distances (compared to the size of the atom) an atom is neutral. However, up close, the electrons of each atom are very close together, much closer than the electrons are to the nucleus. Thus the repulsion from their mutual negative charges overpowers the attraction of the electrons to the other nucleus and the two atoms end up repelling each other. All of this is due to the EM force, not the strong force.
  10. Sep 11, 2015 #9
    yeah i certainly agree with you, i just define it differently than you do, but i still think my question might have some possible merit, maybe charged particles from solar wind or cosmic rays react less strongly with the earth's magnetic field than they should given their speed? cosmic rays move 99.99% the speed of light and some are charged particles, maybe things like alpha particles react more strongly to magnetic fields when accelerated in a collider compared to alpha particle cosmic rays in the earth's magnetic field assuming you scaled the forces proportionally to their strength

    or maybe they're already scaled in a way that magnetic fields have some type of exponential growth which might negate the whole thing, but you could still accurately measure a field with a stationary object
    Last edited: Sep 11, 2015
  11. Sep 11, 2015 #10


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    The laws regarding the interaction of charged particles with electromagnetic fields are understood extremely well and they do not support any of your ideas. Since the discussion has turned to pure speculation, thread locked.
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