# Mass can turn into Energy, or is it Matter which can turn into energy?

1. Oct 26, 2013

### jacket

What's the difference between Mass and Matter? Which of them is equivalent to energy?
Can mass exist without matter?
What does the universe mainly contain? :
Mass and Energy
or
Matter and Energy

2. Oct 26, 2013

### Crazymechanic

mass is just a property of matter.They are kinda one and the same.There is no abstract mass somewhere out there that has no matter attached to it.

Not all matter has mass , some of it is massless like photons , but that another story.
Everything that has mass also has energy, potential, kinetic or otherwise.

The explored universe mainly contains just matter , but there is a huge portion which we don't know yet , we have a fancy word for it " dark matter" not because it's dark but rather because we have a rather " dark picture" of it as of yet.
Anyways whatever is out there must be something physical of that you can be sure.

3. Oct 26, 2013

### Staff: Mentor

Matter is composed of fundamental particles. Mass is a measurable quantity associated with both matter and energy.

Absolutely. A box with light inside has more mass than a box without light. Or, if you want to get rid of the box idea, we can say that a volume of space with lots of light in it has more mass within it than a volume of space with no light inside, everything else being identical.

Ignoring dark energy, as that gets confusing when talking about what the universe is composed of, the majority of the universe is mass in the form of dark matter.

4. Oct 26, 2013

### jacket

Ok. So when we say 'mass turns into energy' then actually we are saying 'a measurable quantity associated with both matter and energy turns into energy'. Sounds confusing to me.
Also if only 'a measurable quantity associated with matter turns into energy' then where is the left out (matter without mass) ? And what is that?

5. Oct 26, 2013

### Staff: Mentor

Yes, it's a bit confusing.
To quote wiki:
In physics, mass (from Greek μᾶζα "barley cake, lump [of dough]") is a property of a physical system or body, giving rise to the phenomena of the body's resistance to being accelerated by a force and the strength of its mutual gravitational attraction with other bodies.

To make it even more confusing, certain units of measurement, like the electron volt, can refer to BOTH mass and energy.

Mass is typically used to refer to the invariant quantity of energy a system has in its own rest frame. For example, a rocket traveling at 99% c will have zero kinetic energy in its own frame of reference, whereas in the frame we are measuring its velocity against it will have a great amount of kinetic energy. However the mass of the rocket will remain the same no matter what frame we measure from, as will the energy associated with this mass. Having a term like "mass" makes it much easier to do physics.

There is no matter without mass. All fundamental particles have mass, as do the composite objects they build into.

Edit: Photons are not usually considered to be matter.

6. Oct 26, 2013

### Staff: Mentor

Mass doesn't "turn into" energy. Mass has energy, and energy has mass.

7. Oct 26, 2013

### jacket

If so, then Matter has mass and mass has energy and again energy has mass...
Who 'has' the property and who 'is' the property?

8. Oct 26, 2013

### Staff: Mentor

Perhaps another way of looking at it will help.

Instead of saying energy has mass, we could say that X amount of mass is equal to Y amount of energy. For example, a kg of mass is equal to approximately 9x1016 joules and vice versa. It doesn't matter which unit you use, the overall effects are the same.

9. Oct 26, 2013

### Staff: Mentor

I don't think that question has any scientific meaning.

How could you experimentally test that question?

10. Oct 26, 2013

### jacket

Ok let me restate my original question:

If we can say X amount of mass is equal to Y amount of energy,
Can we say J amount of matter is equal to K amount of energy?

11. Oct 26, 2013

### Crazymechanic

Yes we can.

Last edited: Oct 26, 2013
12. Oct 26, 2013

### UltrafastPED

Mass converts to energy per E=mc^2.

All matter has mass.

But matter is a non-technical term. Matter = stuff. Most people would say that matter is made up of atoms, atoms are made up of fundamental particles.

13. Oct 26, 2013

### Staff: Mentor

Provided that J is measured in units of mass, then yes, where K = J c².

14. Oct 26, 2013

### jacket

Conclusions: (are they all correct?)

1. Mass and energy are two ways of measuring the same thing.
1. Every system has mass or energy or both (as mass and energy are equivalent)
2. Thus, Matter has mass or energy or both.
3. Mass of a matter can not be 'converted' into energy in the sense that they are actually same thing.

15. Oct 26, 2013

### Staff: Mentor

The first 1. and 3. are fine, but I would restate the second 1. and 2. as follows:

1. Every system that has mass has energy (as mass and energy are equivalent)
2. Thus, Matter has both mass and energy.

By the way, I thought that I should clarify, the mass I am discussing here is "relativistic mass". There is another definition of mass called "invariant mass" which has a slightly more complicated relationship to energy. Specifically: $m^2 c^2 = E^2/c^2 - p^2$

Last edited: Oct 26, 2013
16. Oct 26, 2013

### dauto

Also note that most of the time (>90%) when physicists use the word mass they mean rest mass not relativistic mass. Rest mass is not equivalent to energy since their relationship also includes the momentum p. If you ask my opinion, I would abolish the concept of relativistic mass all together since it is more trouble than it is worth.

17. Oct 27, 2013

### DanCarpenter

Mass is a measurement of matter, which is any physical substance. Matter and energy are not necessarily the same thing, although all matter contains some degree of potential energy. Einstein's theory E=MC^2 states that the amount of energy in matter (E) equals its mass (M) times the speed of light (C) squared.

18. Oct 27, 2013

### ModusPwnd

This is the best answer I think. You dont really need the word "matter" in physics at all, it adds nothing new to any theory.

19. Oct 31, 2013

### jacket

I hope now I am correct:

Relativistic mass is a measure of systems Energy.
Energy is a measure of system's Relativistic mass.

Matter or it's mass, doesnt 'turn into' energy.
Relativistic mass and Energy are two ways to represent a same thing.

20. Oct 31, 2013

### ZapperZ

Staff Emeritus
Er.. no, I think you've made it worse.

We usually do not deal with "relativistic mass". In fact, in many circles, this term is seldom used.

Mass can be converted into energy, and energy can be converted into mass. These are "invariant mass", and that is the only mass that matters (no pun intended).

I am not sure why you have a problem with each one being converted into the other, or why you need to make a distinction between "relativistic" mass etc.

Zz.

21. Oct 31, 2013

### jacket

And perhaps Matter has nothing technical to do in the "mass-energy equivalence".

22. Oct 31, 2013

### ZapperZ

Staff Emeritus
We have no idea what you mean by "matter", or what "nothing technical" actually means.

Unless you know of something, you shouldn't be making statements such as this or you'll run afoul of our rules on speculative post.

Zz.

23. Oct 31, 2013

### jacket

Perhaps I should post a link . http://plato.stanford.edu/entries/equivME/

Everything 'written' next (except the end note) is quoted from this article:

In relativistic physics, as in classical physics, mass and energy are both regarded as properties of physical systems or properties of the constituents of physical systems. If one wishes to talk about the physical stuff that is the bearer of such properties, then one typically talks about either “matter” or “fields.”
....

Are mass and energy the same property of physical systems and is that what is meant by asserting that they are “equivalent”?
The first interpretation (Torretti, Eddington) we will consider answers “Yes” to the first interpretative question posed above: mass and energy are the same property of physical systems. Consequently, there is no sense in which one of the properties is ever physically converted into the other.
.........
Lange (2001, 2002) has recently suggested a unique interpretation of mass-energy equivalence. Lange begins his interpretation by arguing that rest-mass is the only real property of physical systems. This claim by itself suggests that there can be no such thing as a physical process by which mass is converted into energy...

.............................................................................................

Note:
I apologize if it seems like that.

24. Oct 31, 2013

### ZapperZ

Staff Emeritus
It is difficult to carry any kind of rational conversation when one is talking to a series of quote taken from somewhere else.

Please note that you asked the question. When I asked for clarification on what you meant, you gave me nothing but a series of quote from another source. I don't even know if you actually understood what you quoted. Do you even know the physics involved in the source that you are citing?

A lot of these are "semantics", not physics! Anyone who thinks that the e-p pair is identical to photon that created it has a lot of explanation to do!

If you read something, and you didn't understand it, then cite it and ask! Don't respond to something by simply quoting off some webpage or source. A parrot can do that as well!

Zz.

25. Oct 31, 2013

### jacket

Well, okey ZapperZ, you are the Mentor here. I expect help from you.
Anyone reading this post with a rational mind will see, whenever I try to say something from my own or try to clarify what I am trying to say, you reply like
I am not "Making statements", I am trying to know if those statements are right or do they make sense at all. I got some ideas by studying some texts and felt confused when I tried to understand those concepts. And so I asked here, for a discussion to clarify my confusions. And I did't 'invent' anything.
Even if I show you one example of from where I got those ideas, you say,
I am 'quoting' because if I dont quote, you are saying I am making 'foul statements'.
Now I wonder why you don't Correct my 'foul statements' and explain things clearly? Or explain the contradiction of concepts? (I think *now* many viewers would be happy to get the explanation.)
It doesn't matter really. If I understood, then I wouldn't have asked here. And if you understood (which of course you did) you can explain.

"If you can't explain it simply, you don't understand it well enough." - Albert Einstein

Applies to everyone!