# Q & A: Matter and Energy

Q:
Does energy contain matter?
- colin Theall (age 9)
Plano,Tx,USA
A:
Actually, energy is matter, and matter is energy. This surprising fact was proved by Einstein in 1905 along with his special theory of relativity. Before, scientists had recognized two important laws, the conservation of mass and the conservation of energy. These laws meant that the total amount of energy or mass in the universe would never change but remain constant. Einstein's famous equation, E=MC^2, says that there is a specific quantity of energy associated with a mass, and a specific amount of mass for a certain amount of energy. E stands for energy, M stands for mass, and C^2 stands for the speed of light multiplied by itself once. Now there is one law called the law of conservation of mass-energy. This allows for energy to change into mass and mass into energy while keeping everything constant. One great example of this is the sun. In the center of the sun, four atoms of hydrogen (without electrons) can fuse to form one atom of helium (also without electrons). The mass of the four hydrogens is larger than the mass of the helium that is left. Where did the rest of the mass go? The answer is it was converted into energy that may eventually get to our planet to keep all life on it going. The sun does this very many times a second. So next time you have a sunny day, think of how Einstein's equation showed us how it was done.

John ZuHone

(published on 10/22/2007)

## Follow-Up #1: energy and matter

Q:
i woul like to know if energy contains matter
- Anonymous
A:
OK, the last answer may have been tough so well try this from a little different angle.

We know what the meaning of the word energy is. We have a quantity called energy in the equations describing how things move around and take on new forms. Energy comes in various forms, including motion, electromagnetic fields, and the existence of particles with mass.

I dont really know what the word matter means. I guess it means particles with mass like those that make up the familiar stuff around us. Most of the time, those particles are a part of the things that have energy, but you can also have energy without any massive particles.

Mike W.

(published on 10/22/2007)