# So what exactly E=mc^2 says ?

1. Jan 1, 2010

### tell_me_why

So what exactly E=mc^2 says ??

ok all know E=mc2. but apart from that small matter is equi to huge amount of energy what other things can be derived.

1) how could matter directly relate to energy and not individual elements like Uranium, hyd etc. doesn't it mean that all elements and made of one and only one basic element and hence we can say n * basic element = m ,so E= n* basic element * c^2.

what do you guys think ?? if u feel its bogus then explain me how u relate 1gram Uranium produces same energy as 1 gram hydogen asuming the energy conversion is done 100%.

2. Jan 1, 2010

### espen180

Re: So what exactly E=mc^2 says ??

1 gram of uranium would produce the same ammount of energy as 1 gram of hydrogen provided all the mass is completely converted to energy. This is not the case in energy production from fuel. When we use these elements to make usable mechanical energy, we burn hydrogen in okygen, making water vapor. In the case of Uranium, the energy comes from fission.

3. Jan 1, 2010

### tell_me_why

Re: So what exactly E=mc^2 says ??

so if hydrogen and uranimum (1 gram) produes different energy then E=mc2 is incorrect..

thats why i said " when converted properly ".

4. Jan 1, 2010

### tell_me_why

Re: So what exactly E=mc^2 says ??

Or do we need equations like:

E=mc^2 ----for fission

E=mc^2 * .00000001 ------for combusion like charcoal , wood.

E=mc^2 * .000001 -------for burning petrol.

but we donnt have right ........only E=mc^2.

this simply means every matter is made of same basic element.

5. Jan 1, 2010

### espen180

Re: So what exactly E=mc^2 says ??

No, this is not the case. The reason is that when we use H or U to get energy, we don't convert all the mass to energy. When burning hydrogen, we are breaking and forming covalent chemical bonds betweeb atoms, which is completely different from fission.

The mass-equivalence formula states that mass and energy are exchangable through a numerical constant c2.

For example, General Relativity, predicts that a mass m and an energy E=mc2 will curve space-time equally.

Last edited: Jan 1, 2010
6. Jan 1, 2010

### edpell

Re: So what exactly E=mc^2 says ??

I would agree. But energy condenses out in many differing forms. So I guess the question is why is the symmetry broken.

7. Jan 2, 2010

### tell_me_why

Re: So what exactly E=mc^2 says ??

anyway i stongly feel that there is some basic element..

sorry I am not a physics student right now and not aware of any latest therories..

we know atom are madeup of electron and protons and neutron.

quite possible these particles are madeup of some basic elements, and who knows some day we find that

Electron= basic elements * n ---some engery is required to form an electron
similary for proton and neutron...all this should point to basic elements.

its like building madeup of bricks..though different building looks and number of floor but same basic elements.

Last edited: Jan 2, 2010
8. Jan 2, 2010

### DaveC426913

Re: So what exactly E=mc^2 says ??

Yes. Protons, electrons and neutrons are your basic building blocks.

9. Jan 3, 2010

### TauCrouton

Re: So what exactly E=mc^2 says ??

Although String Theory says otherwise ;)

10. Jan 3, 2010

### DaveC426913

Re: So what exactly E=mc^2 says ??

Well, so does the standard model: quarks make up protons. But I think that, since the OP is asking about Uranium and Hydrogen, that that is the level of building blocks he needs to understand.

11. Jan 4, 2010

### tell_me_why

Re: So what exactly E=mc^2 says ??

my question is related to mass and not to specific elements..
as we are dicussing E=mc^2 which is based on mass and not individual elements.

how it is possible that same mass produce same amount of energy even if they belong to different elements. Logically this is possible only if all elements are made up of some basic element which is reason for mass and energy. as energy is based on this basic element so no matter what element is used to produce energy it will always follow E=mc^2.

12. Jan 4, 2010

### DaveC426913

Re: So what exactly E=mc^2 says ??

What are you not understanding?

If you annihilate one proton, you will get a release of energy equivalent to one proton. It doesn't matter what element that proton is part of. (Note that this is highly oversimplified. There is a host of interactions that will give you different numbers, but they are all accounted-for.)

Yes. That basic unit is the proton (or neutron).

Last edited: Jan 4, 2010
13. Jan 5, 2010

### yuiop

Re: So what exactly E=mc^2 says ??

When you burn wood in air you get some energy, but you are still left with a lot of the original mass of the wood in the form of ash, soot, smoke, carbon dioxide, water etc. if you could carefully weigh all the waste products you would find a tiny amount of mass was missing and that missing mass *c^2 is equivalent to the energy released. The same is true of fission. After fission there are some remaining fission products but again the missing mass*c^2 is equivalent to the energy released. It is just that fission is more efficient than burning wood, but fission is not a 100% conversion of the nuclear fuel to energy either.

14. Jan 6, 2010

### edpell

Re: So what exactly E=mc^2 says ??

I think you are right. I think this is the premise that drives people to seek unification. But of course at low energy there is some serve symmetry breaking electrons do not seem like quarks, which do not seem like protons, which do not seem like .....