# B Can you reverse Einstein's famous E=mc^2 equation?

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1. Dec 28, 2016

### gabi123

E=mc^2 states that when you speed up matter to the speed of light, it becomes pure energy, of mc^2 joules. Now, if that is true, can you reverse the equation? Wouldn't energy speed up to the negative speed of light(-c^2), turn into matter? Or is that the wrong balance?

2. Dec 28, 2016

### Orodruin

Staff Emeritus
No it does not state that. It states that the mass in any object corresponds to an equivalent amount of energy - relating the energy of an object to its inertia. Also note that there is no such thing as "pure energy". Energy is a property of matter and fields, not a substance of its own.

It is not, so I will not comment on the rest of your post.

3. Dec 29, 2016

### lychette

It is true to the extent that a certain amount of energy can be the equivalent amount of mass.

4. Dec 29, 2016

### Orodruin

Staff Emeritus
Did you even read the OP? The first sentence in the OP is simply false and makes no sense in relativity.

5. Dec 29, 2016

### lychette

I did read the first statement but it in no way contradicts his/her later statement that energy can be converted into mass according to the theory of relativity.
My contribution relates to that second statement.

6. Dec 29, 2016

### Orodruin

Staff Emeritus
Please read the statement again. It refers to reversing "when you speed up matter to the speed of light, it becomes pure energy", which is pure nonsense in itself.

7. Dec 29, 2016

Staff Emeritus
Funny, I thought that's what I wrote.

Since the whole premise of this thread is based on something incorrect, what do we have to discuss?

Last edited by a moderator: Dec 29, 2016
8. Dec 29, 2016

### Orodruin

Staff Emeritus
It was, but you deleted that post.

At B level, I think the important thing is to straighten out people's misconceptions rather than having a high level discussion. If we cannot do this, then what is the point of a B level thread? Nobody should expect (or engage in!) high level discussions at B level. Having misconceptions - often fueled by popular science - is not directly equivalent to being a crackpot.