# Infinite Mass-energy?

*Most recent answer: 10/22/2007*

Q:

Now you’ve said that you cant move faster then the speed of light because (skipping a long explnation) your mass becomes infinite and then you would need infinite energy
Now beacise of E=mc^2 we know that means mass is energy
So if mass is energy and you had infinite mass that would mean you had infinite energy as well
so thats means you would be able to go the speed of light or faster
does this work?

- James

U.S

- James

U.S

A:

One part of your argument is correct. If you had infinite inertial mass
then you would also have infinite energy, since they are really just
the same thing measured in diffefent units (E=mc^2). However, the
second part, where you say ’hey that infinite energy is just what you
need’ is circular. Remember, the argument was that the energy would
have to be infinite IF you were travelling at c. You can’t use that to
say that therefore you can get enough energy. The limits on where the
energy comes from are still the usual ones, and there’s no way you are
going to get infinite energy.

Mike W.

In more modern language, E^2=(mc^2)^2 + (pc)^2, where p is the momentum, and m is an "invariant" mass (you can call it the rest mass). Increasing the speed of something towards the speed of light increases its momentum to infinity, and also its energy. Not only is there no such thing as infinite energy, there’s also no such thing as infinite momentum.

Tom

Mike W.

In more modern language, E^2=(mc^2)^2 + (pc)^2, where p is the momentum, and m is an "invariant" mass (you can call it the rest mass). Increasing the speed of something towards the speed of light increases its momentum to infinity, and also its energy. Not only is there no such thing as infinite energy, there’s also no such thing as infinite momentum.

Tom

*(published on 10/22/2007)*