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Large Hadron Collider questions

  1. Aug 24, 2009 #1
    I watched some interesting videos on the Large Hadron Collider (LHC) and it raised a whole ton of questions. If my questions do not make any sense, perhaps the video itself, though clever and catchy, is not credible. ( http://technology.todaysbigthing.com/2008/09/11 [Broken] + http://technology.todaysbigthing.com/2008/09/12 [Broken])

    If the second video is credible:

    1. How do protons get heavier when they approach the speed of light? ("99.9% of the speed of light")
    -The video said that because energy is added, but the protons cannot go any faster, they gain mass, and I do not fully understand the translation from mass into energy and the other way around.

    2. What is dark matter?

    3. What is anti matter?

    4. The second link also mentioned that if they cannot explain what happened to all the anti matter from the big bang that they would need new physics because the standard model was missing something, but could this problem be reworked to prove the necessity for a super intellect creator who could break His own physical laws?

    5. How does the LHC see anti matter, what is it, or what isn't it?

    6. has the existence of gravitons been proven?

    7. how does the LHC guide the protons, what keeps them on the same track in the vacuum?

    please reference the question numbers so I know which one you are answering, and thank you :smile:
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Aug 24, 2009 #2


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    Everything gains mass as it gets heavier, but it's only when you get close to the speed of light that the effect is big enough to notice. This is Einstein's special theory of relativity.

    If you look at the speed a galaxy rotates you can work out it's mass from Newton's law of gravity - but if you add up the mass of all the stars in the galaxy you only get 10% of that mass. Dark matter is a term for all the unknown stuff making up the rest of the mass.
    We don't know 'what' it is yet. It's not really anything to do with the LHC.

    All the sub atomic particles that make up atoms have an opposite particle, these have the same mass but the opposite charge. So a proton goes with an anti-proton, also when matter and anti-matter meet they explode rather violently.
    This means that if protons go clockwise in a circle in the LHC the opposite charged anti-protons will go anti-clockwise in the same circle. When they meet the results are interesting.

    In 1800 we couldn't explain the link between electricty and magnetism - then Maxwell turned up.
    In 1900 we couldn't explain the orbit of mercury - then Einstein.
    So we probably don't need a super hero to sort out the matter/anti-matter problem.

    The explosion when matter and anti-matter meet create a whole bunch of particles, x-rays etc which are detected by electronic and optical sensors.


    Magnets. In a magnetic field a charged particles feels a sideways force. Get the radius of the ring, the strength of the magnet and the speed of the particles correct and it's just liek the indy500.
  4. Aug 24, 2009 #3
    In old fashioned books, we used to say that "mass increases as particles approach the speed of light". In fact, although historical, this point of view is often considered rather confusing. The important equation to remember is [itex]E^2=p^2c^2+ m^2c^4[/itex] where the mass is a fixed parameter describing a particle. If the particle is at rest, then the momentum equals zero [itex]p=0[/itex] and the formula reduces to [itex]E=mc^2[/itex]. So the mass really is a form of stored energy, or frozen energy, in a particle at rest. If the particle is moving and you insist to compute an equivalent rest mass that the moving particle would have if it had no momentum, you "simply" arrive to the point of view conveyed in the video.

    We do not really know what dark matter is. As of today, dark matter has been detected in the movement of large astrophysical objects, such as galaxies, as well as the way light propagates, by assuming correct gravitational laws in Einstein's gravity. There are pretty much as many hypothesis for what Dark Matter is as you can find theoreticians interested in the question.

    What ?

    Anti-matter is matter with all charges reversed. An example of charge is the electric charge. The standard model also has other charges, but it mostly works the same. Charges are defined as (discrete) quantities conserved during reactions. For instance, a neutron can decay into a proton, an electron and antineutrino. The electric charge is conserved : none before, and +1 for the proton plus -1 for the electron after. In this example, the antineutrino carries -1 leptonic charge, whereas the electron has +1, and both proton and neutron have zero leptonic charges.

    We infer the existence of charges from symmetry properties in the spectrum of and reactions among particles. Then we can use the assumption of those symmetries and charges, and come up with predictions for new particles and/or rates for other reactions.

    No single graviton has ever been detected, and this will be (very) difficult.

    Protons can be accelerated using electric fields, and focused using magnetic fields.

    collision with mgb_phys
  5. Aug 25, 2009 #4
    Thank you, thank you, thank you, that clarified a lot. my curiosity about all this has been like a bad itch, thanks for scratching it! :biggrin:
  6. Sep 2, 2009 #5
    "This is a collection of facts and figures about the
    Large Hadron Collider (LHC) in the form of questions
    and answers. Questions are grouped into sections,
    and answers are often two-tier, with more details in
    the second level. Please note that when speaking
    about particle collisions in the accelerator, the word
    ‘interaction’ is a synonym of ‘collision’."

    Awesome stuff! :smile:
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