Free Energy: E=MC^2

I’ve been interested with some of the more exotic aspects of physics since watching NOVA’s The Elegant Universe. It was mostly about the up and coming String Theory, but also covered the history of the field. By the way, interesting thing about String Theory, it proposes that there is a small chance that you can walkthrough a wall due to quantum tunneling. However, the probability is so small, the time it would take you to try is longer than the projected life of the universe.

E=MC^2 is probably one of the most famous equations in the world. Everyone’s heard of it, but few actually know what it means. Energy equals the product of mass and the speed of light squared. Now the speed of light is a very big number (299,792,458 m/s). So, this means any mass can be converted to energy (a lot of energy!).

Nuclear reactions rely on this principal to create energy. In a nuclear reaction that produces energy, two atoms combine (fusion) or one atom splits (fission) and at the end of the reaction the products weigh less than original reactants. That lost weight is responsible for the sun’s energy and the destructive power of an atomic bomb. That’s a lot of free energy.

Now, when I say free energy, I don’t mean G, although some of the energy that is released is. I mean using the dirt on the ground or particles of air to power our cities. But we’re not there yet, and perhaps we never will be.

You have probably heard of the second law of thermodynamics. Basically it says that entropy can never decrease. When energy is used to do work, some of it is lost as heat and friction and can never be used again. There is an absolute limit on the amount of work that can be done in the universe. One day, the universe will be nothing but entropy with no organization. Rather depressing isn’t it.

I would like to leave you with a story: The Last Question by Isaac Asimov. Perhaps a bit optimistic about the future of human race, but an amusing tale nonetheless.