• Question: what does e=mc2 mean

    Asked by abdullahbrazilali to timcraggs, Stuart, Mark, Jo, Donna on 16 Jun 2010 in Categories: .
    • Photo: Tim Craggs

      Tim Craggs answered on 16 Jun 2010:

      It is an equation that Einstein came up with which relates matter, mass (m) to energy (e) and the speed of light (c).

      Perhaps Mark can tell you what it actually means for the universe?

    • Photo: Mark Lancaster

      Mark Lancaster answered on 16 Jun 2010:

      “E” is energy
      “m” is the mass when the thing is at rest.
      c2 is the speed of light (in a vacuum) squared (this is a huge number) ie 9x1016m2sec-2

      If you take anything (including you) then 99.9% of the mass and hence the energy is in the atomic nucleus. So you can get to this massive amount of energy if you can cause the nucleus to split up (fission) or fuse (fusion).

      The energy is enormous. What’s the energy in one litre of water :

      1 litre = 1kg
      So E = 1 x 9 x 1016 = 9 x 1016J

      The UK consumes 9 x 1018 J of energy in a year – so the energy in 100 litres of water (which is about 20 toilet flushes worth) could power the UK for a year…. we just need to get the energy out of the nucleus…

    • Photo: Joanna Buckley

      Joanna Buckley answered on 16 Jun 2010:

      Our old friend Einstein came up with it. It’s probably the most well known equation and it basically is the formula for the conversion of mass to energy.

      How cool would it be to come up with an equation and forever to be remembered for it?

    • Photo: Donna MacCallum

      Donna MacCallum answered on 16 Jun 2010:

      E = mc2 is an equation written by Albert Einstein, where energy (E) equals mass times the speed of light squared. This is the theory of relativity.

      In the definition, because the speed of light squared is a large number, this equation demonstrates how a small mass can produce a huge amount of energy.

      Bit too much physics for me though!

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