# How can mass be converted into energy?

Physicsissuef
how can mass be converted into energy when the mass is already energy? I was reading about mass defect, and it says that the mass is converted into energy. How is that possible?

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Mass is converted into BINDING energy - that is the mass defect.

Physicsissuef
but isn't the mass itself energY? How energy can be converted into energy?

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Do you remember this fundemantal physic-law?

"Energy can neither be created nor be destroyed" There exists different kinds of energy, kinetic energy, potential energy, electrostatic energy, chemical energy, heat, Mass etc. You may transform the energy into any of these kinds as you wish, as long as the total amount of energy is conserved -> Principle of energy conservation.

Remember the introductory example in mechanics where you add energy to roll a ball up the hill (gives it potential energy). And then when you release the ball, it roll down the hill (gains kinetic energy). Now how did you get the energy to roll the ball up the hill? Probably by eating some food (chemical energy), which your body transformed into mechanical energy. And the food gained its energy from the sun (heat).

The same way it works in this situation, you have different kinds of energy, beening transformed into one another. It's nothing mystical.

Physicsissuef
And is the mass energy, because I am not sure?

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And is the mass energy, because I am not sure?

Yes, you may regard mass as one form of energy

Physicsissuef
Ok. Thanks very much for the help. :)

Physicsissuef
And can I ask you one very interesting question? If we have only one nuclei (lets say 1 neutron 1 proton), and if we separate it on half (1 neutron separated from 1 proton), will then the binding energy be converted into mass?

Mentor
Look up the mass of a deuterium atom, and compare it to the masses of a hydrogen atom and a neutron.

Physicsissuef
The mass of a hydrogen atom is less than the mass of neutron + mass of proton. I already know that. But I want to know how did the scientist find the mass of neutron and proton, when all of the neutrons and protons are paired into nucleus? And again will then the binding energy be converted into mass?

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We can't speak about "if we move the proton and neutron further away", since we are the quantum mechanical world.

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I think what you really are asking if energy can be converted into mass, and yes - that is possible. That's how particle creation at accelerators are done.

Physicsissuef
When they were connected mass has been converted into energy (mass defect), now will the process be reversible? If we separate them, will there binding energy be converted into mass?

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When they were connected mass has been converted into energy (mass defect), now will the process be reversible? If we separate them, will there binding energy be converted into mass?

hehe

well if you separate them as much as jtbell said, then they will have more mass.

Physicsissuef
Its very strange from one side, but it is logical on the other side

azzkika
does the fact that energy can become mass mean it already has mass? i am very puzzled how you could in principle, add a zero weight to one side of scales yet make it heavier, yet if energy is massless that is what is occurring if energy has zero mass but can become mass.