Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Mass to light?

  1. Feb 1, 2007 #1
    I am only completing high school physics, but I hope to study physics at university, so bear my level of knowledge in mind!


    I understand that at the most fundamental level, matter is just a low frequency wave. Photons, or light, are very high energy waves. Would it be theoretically possible to some how increase the energy of a particle with mass and turn it into a photon?

    I don't know whether there is a major flaw in that or whether even my statements are entirely correct!

    Any input would be great!
     
  2. jcsd
  3. Feb 1, 2007 #2

    ranger

    User Avatar
    Gold Member

    Well a photon always travels at the speed of light and it has no rest mass. The problem here is that a particle with mass cannot be accelerated to attain the speed at which photons travel. This is because as the particle gets closer and closer to the speed of light, more and more energy must be expended to increase its velocity by very small amounts. Hence an infinite amount of energy would be needed to achieve the speed of light. Summing it up, only massless particles can travel at the speed of light.

    BTW, the energy of a photon is related to its frequency. So it depends on your concept of "high energy". For instance, gamma rays, which have very energetic photons (high frequency), have very high energy levels.

    However if you are talking about the collisions of particles, it happens for example when a particle and its anti-particle collide and annihilate each other. Both of these particles have mass and becuase of the conservation of energy-mass, the mass cant just simply vanish. Instead it is converted to energy. For instance when a electron and its anti-particle (positron) collide, they annihilate each other and in the process, photons are created.
     
    Last edited: Feb 1, 2007
  4. Feb 2, 2007 #3

    Mentz114

    User Avatar
    Gold Member

    Hi Joza, just how light turns into matter/anti-matter is not understood at present.
    Incidentally, matter is a very high frequency wave. The frequency of a slow electron's phase is about 10^50 Hz. An electron's 'size' is also many magnitudes
    smaller than the wavelength of the light that may produce it.

    If I'm wrong on any of these points, I'm sure someone will correct me.

    M
     
    Last edited: Feb 2, 2007
  5. Feb 2, 2007 #4
    In a nutshell, what I'm getting at here is this:

    If somehow, the mass of a spacecraft could be turned into light, it would be able to travel at the speed of light and also be free from G forces etc. because it has no mass.

    Is this at all plausible?
     
  6. Feb 2, 2007 #5

    Mentz114

    User Avatar
    Gold Member

    If you turned your spacecraft to light it wouldn't be a spacecraft anymore.
    Light and matter are completely different things.

    Study Maxwell's equations.
     
  7. Feb 2, 2007 #6
    Thats true, but could it then be reversed and light goes back to mass? I have not encountered Maxwell's equations yet.
     
  8. Feb 2, 2007 #7

    ranger

    User Avatar
    Gold Member

    It would do you some good to read on pair production. This is the creation of a particle and its anti-particle from a photon without violating the conservations laws. The photon must have enough energy for the particle rest mass energy.

    http://en.wikipedia.org/wiki/Pair_production
     
  9. Feb 3, 2007 #8

    Mentz114

    User Avatar
    Gold Member

    Hi Joza,

    it is good to be imaginative and ask lots of questions, but in the end physics is equations. The answers, such as they are, lie there. You have much to look forward to.

    M
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?