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

How to release energy in E=mc2?

  1. Jan 9, 2009 #1
    I know that anything with mass has a conserved energy within it. In that sense, wouldn't it be logical to say that even a paperclip could destroy a city in America (since c is such a huge number.) So in that case, how do you release the energy?

    *note: I'm not trying to destroy the world, I just want to know.
  2. jcsd
  3. Jan 10, 2009 #2
    There is no practical way....currently. But likely the energy equivalent in paper clip if released in a short time, could destroy it..or perhaps power it for an extended period.

    If you read about nuclear fission and fusion you'll note there are currently only a very small group of materials/elements that are self sustaining, good for the production of power in specific environments...related to binding energy and atomic number (nuclear forces). For example, self sustaining nuclear fission requires moderators to slow neutrons down to stimulate further neutron emissions. And U238 doesn't work,,,"enriched" uranium with extra U235 is required...and even so only a tiny amount of the uranium is transformed to energy..is it maybe 1% or 2%??...I've forgotten but it's small.

    Stars are better at creating elemtns and releasing energy than we. Stars convert matter to energy and the other heavier elements but it too is limited...once iron is reached after the creation of a succession of heavier elements via fusion a star can go no further..it collapses under gravitational forces. If big enough, when it collapses, a supernova is born and most of the heavier elements can be synthesized....before it explodes and spreads heavy elements through the universe....which is then incorporated in the next generation of stars and plants....hence you are made of star/supernova remnants!!

    We can't produce most of what I've described. Stars are "smarter" than we.

    If this answer doesn't do it for you, try posting in Nuclear Engineering...Or High Eenergy, Nuclear, Particle.....in other FORUMS....
  4. Jan 10, 2009 #3


    Staff: Mentor

    Even in nuclear reactions only a small fraction of the mass is converted to energy. If you want complete conversion you need to annhilate it with anti-matter.
  5. Jan 10, 2009 #4
    ...but you need at least the same amount of energy to create it, so it's useless.
  6. Jan 10, 2009 #5


    Staff: Mentor

    Well, there are several different naturally occuring isotopes which undergo positron emission (positive beta decay) where a proton turns into a positron (an anti-electron), a neutron, and a neutrino. Potassium 40 is one such isotope which is very common in the human body, and is one typical source of background radiation seen in PET imaging.

    It doesn't really take energy to make anti-matter that way, although it certainly wouldn't be a very practical energy source if that is your goal.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook