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Name: Mridul
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Is energy a form of matter? My school teacher says so by quoting E=mc^2 relation. But by definition the matter should have mass, shape and size; and it should be localized. I am not convinced, and am confused. Please clarify.

You have made some assumptions about the "properties" of matter that are not universally correct. Matter does not always have a specific shape (liquids take on the shape of the vessel containing the liquid), nor is matter always localized (a gas occupies both the shape and the size of the vessel containing the gas, so it does not necessarily have a specific fixed location). Even solids do not have a specific size (the size of a solid depends upon its temperature and the pressure that is exerted upon it, and can change shape by stretching, bending etc.).

There are many experimental results confirming that "energy" and "mass" are equivalent, although the enormous equivalence factor (c^2) means that under "normal" conditions the two seem to be distinct. Two direct results confirming that equivalence are: 1. the annihilation of an electron and its anti-particle the positron, produces electromagnetic radiation whose energy is precisely the given by the relation E=mc^2. The second result is nuclear fusion and fission in which energy and mass are not individually conserved, but rather it is the collective mass/energy together that is conserved. There are thousands of examples verifying that equivalence.

I think that it is the fact that in our "everyday" conditions that energy and mass appear to be distinct quantities, but it is the size of (c^2) that makes this appear to be so. Under the proper conditions the equivalence can be demonstrated.

Vince Calder


The proper way to state it is, "Matter is a form of energy." Energy has many locations. Energy is in the temperature within matter. Energy is in heat as it transfers from one material to another. Energy is in the motion of an object. Energy is in the force between objects, even the force between atoms. Energy is in light.

Albert Einstein discovered that energy is in the mass of an object. When that energy is released, when mass is converted into a more familiar form of energy, the units of energy equals the units of mass multiplied by c^2, or (3.00x10^8 m/s^2. This released energy is usually as light or heat. These tend to be the easiest to create and the most difficult to control.
A way to see that mass is a form of energy is to consider a proton. Scientists have discovered particles known as quarks. Quarks have almost no mass. The mass of up and down quarks are much less the mass than electrons. A proton is made of two up quarks and one down quark. The quarks move around very much. This is kinetic energy. The force between the quarks is the "strong force". This force is considered to be the strongest force in the universe. The strong force has potential energy, just as gravity and spring forces do. We see the total of these internal energies as the mass of the proton.

Dr. Mellendorf

It is more accurate to say that matter is a form of energy; mass IS energy! (A little bit of mass is a lot of energy.)

In response to your objections: does matter really have shape and size? The shape and size we observe of material objects is a consequence of forces between elementary particles so small that there is so far no evidence that they actually have any size. And as for being localized: the only reason particles can be localized is because their masses (rest energies) are so large. There's always some indeterminacy of the location of any object due to the uncertainty principle.

Richard Barrans

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