# Can we convert energy to mass?

Can we convert energy to mass??

hi guys...,
i'm new to this site. so please just spare me if i've done something wrong..coming to the topic we all know that mass can be converted to energy..but can we convert energy to mass according to the equation e=m*(c^2)..??

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I'm not a particle physicist, but I imagine the man-made synthesis of transuranic elements via particle accelerators is technically turning energy into mass.

Scientists are creating new elements all the time. These new elements have more mass per nucleon than the "older" ones (like element nr. 133 has more mass per nucleon than nr. 132). Argh, please somebody who knows English properly explain this?

Anyway, this means that scientists are turning energy into mass.

EDIT: Heck, wouldn't making chemical reactions where the enthalpy change is positive mean the same thing? I.e. for example 2H2 and O2 have more mass than 2H2O? I seem to recall the reason, at least partially, that energy is released when H2 and O2 react being mass is liberated into energy?

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Drakkith
Staff Emeritus

Yes! When we collide two electrons together at very high energies the resulting mass of created particles are far beyond the original rest masses of the two electrons! The same thing happens for other particles too.

Edit:As Dalespam points out below, it is more correct to say that MATTER can be converted to energy and vice versa, as energy always has mass.

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Dale
Mentor

We don't convert energy to mass, energy already has mass without any conversion needed. However, we can convert energy to matter which is probably what you were really asking.

Scientists are creating new elements all the time. These new elements have more mass per nucleon than the "older" ones (like element nr. 133 has more mass per nucleon than nr. 132). Argh, please somebody who knows English properly explain this?

Heck, wouldn't making chemical reactions where the enthalpy change is positive mean the same thing? I.e. for example 2H2 and O2 have more mass than 2H2O? I seem to recall the reason, at least partially, that energy is released when H2 and O2 react being mass is liberated into energy?
Indeed. H2 and O2 have a tiny bit more mass than they do when combined. The energy release is about 285 kJ/mol, or about 3 ng/mol.

Drakkith
Staff Emeritus

We don't convert energy to mass, energy already has mass without any conversion needed. However, we can convert energy to matter which is probably what you were really asking.
Exactly. E=MC^2 is NOT saying that mass can be converted to energy and vice versa, it is saying that all energy has an accompanying amount of mass. When you add or remove energy from a system you also add or remove mass as well.

Exactly. E=MC^2 is NOT saying that mass can be converted to energy and vice versa, it is saying that all energy has an accompanying amount of mass. When you add or remove energy from a system you also add or remove mass as well.
you meant to say that when i push an object there is an energy imparted to it..and this energy alters its mass...as energy has an accompanying amount of mass

I'm surprised that nobody has mentioned "pair production" yet.Try googling.

you meant to say that when i push an object there is an energy imparted to it..and this energy alters its mass...as energy has an accompanying amount of mass
no, energy is not transformed into mass in your scenario. You get energy to push the object from chemical reactions inside your muscles. After a while due to friction the object which you had pushed will have transformed all its kinetic energy into heat

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Dale
Mentor

you meant to say that when i push an object there is an energy imparted to it..and this energy alters its mass...as energy has an accompanying amount of mass
Yes, exactly.

no, energy is not transformed into mass in your scenario. You get energy to push the object from chemical reactions inside your muscles. After a while due to friction the object which you had pushed will have transformed all its kinetic energy into heat
And heat has mass. Energy has mass, it does not need to be "transformed into" mass.

Earlier today I was wondering if it were possible to generate protons from electrons, positrons, neutrinos and/or anti-neutrinos using a particle accelerator.

Drakkith
Staff Emeritus

Earlier today I was wondering if it were possible to generate protons from electrons, positrons, neutrinos and/or anti-neutrinos using a particle accelerator.
I believe this is all possible and regularly occurs at most modern accelerators/colliders. It isn't controlled, as we cannot simply say "I want 3 protons and that's it from this collision". An assortment of different particles are created.

dalsespam, I learned from my teacher that energy and mass are two sides of the same coin, so to speak. I'm not sure what you mean? Energy and mass regularly change forms, don't they?

Dale
Mentor

dalsespam, I learned from my teacher that energy and mass are two sides of the same coin, so to speak. I'm not sure what you mean? Energy and mass regularly change forms, don't they?
Energy certainly regularly changes to other forms of energy (e.g. kinetic energy to electrical energy). I don't know of any "forms" of mass.

Energy is the capacity of a system to do work. Mass is a measure of the amount of inertia of a system. They are both properties of systems, they are not things in and of themselves. A system can have more than one property, for example it can be blue and hot. Similarly, a system can have both inertia (mass) and the capacity to do work (energy). E=mc² is not about "changing" energy into mass. It is about the fact that a system with energy has a certain amount of inertia, and a system with mass can do a certain amount of work.

I meant that energy can change form into mass and vice versa.

Well, to be hyper-formal: energy/mass can change its appearance

:P

Dale
Mentor

I think I have said this 3 times now in this one thread. Energy does not change form into mass, it already has mass to begin with even without changing form.

Mass is not a form of energy.

You can, however, produce matter given sufficient energy in a particle collider. In such a case you would get a transformation of energy from e.g. kinetic energy to rest energy. But the mass would be unchanged.

Drakkith
Staff Emeritus

I meant that energy can change form into mass and vice versa.

Well, to be hyper-formal: energy/mass can change its appearance

:P
This is a very widespread misconception. Mass and Energy NEVER change into one another. It isn't possible. As Dalespam said, Mass and Energy aren't "things" in themselves. Energy is the capacity to do work. It describes the interactions between objects. Adding energy into a system increases its mass. In a chemical or nuclear reaction the released energy has mass and removes that mass from the reaction products in the form of heat and light.

What kind of mass would we say a photon has. Aren't there like 3 different types of masses.

Drakkith
Staff Emeritus

Photons don't have rest mass, they have momentum. According to GR the effect is identical concerning the effects of gravity, as photons are affected by gravity and also generate their own gravitational field. When the photon is absorbed the momentum is transferred to the object, which increases its mass. In effect the mass has been transferred from the object emitting the photon to the object absorbing it.

so a photon has an effective mass .

Drakkith
Staff Emeritus

so a photon has an effective mass .
I think it is more accurate to say that a photon has no mass, but has momentum which can transfer mass.
Edit: I think it really depends on your definition of mass.

ok , I was just reading Dalespams post and he said the mass would be unchanged but we could transform energy into matter.

Drakkith
Staff Emeritus