When does energy turn into matter?

[roscoe1911]

Thanks, I have a hard time wrapping my head around this.

 

[SAR 6114]

this is E=Mc2 (mass-energy equivalence) not the theory of relativity....................HTH HaND

 

[streetroc]

This points to interdimensional expansion. As our Universe gains mass, it may be pulled to another mass with greater and greater velocity.

How would our universe be gaining mass? Just because the space is expanding doesn't mean there is any more stuff being created in that space.

 

[tywest]

The universe is finite and it has an edge. Beyond that there is nothing because time and space began at the big bang and only exist within a 13.7 billion light year radius from the singularity that was at the center of what is now the universe. So it is literally expanding into nothing. Or at least not into any kind of dimension that we can understand.

Whats really crazy is that you would expect gravity to pull things together and slow the rate of expansion. What we have recently discovered however is that the universe is not slowing down, but speeding up. Scientists still aren't really able to explain why although this has been proven many times to be the truth.

where do you get the universe is finite and has an edge?

Harvard also teaches there was no point of singularity btw........

 

[Laufen]

How would our universe be gaining mass? Just because the space is expanding doesn't mean there is any more stuff being created in that space.

More concentrated mass would be more correct. Matter is still clumping together. I don't know, but it's fun to think about it.

 

[tywest]

More concentrated mass would be more correct. Matter is still clumping together. I don't know, but it's fun to think about it.

right.....no more atoms being created just re-arranging they say.

 

[8675309]

this is E=Mc2 (mass-energy equivalence) not the theory of relativity....................HTH HaND

wrong,
E=McHammer

 

[streetroc]

where do you get the universe is finite and has an edge?

Harvard also teaches there was no point of singularity btw........

Because nothing existed before the big bang because there was no time or space for it to exist in. The big bang happened 13.7 billion years ago so even light itself could not have traveled more than 13.7 billion light years. (although I guess as space itself expands the light has to travel farther in proportion?)

And really? I thought that the universe came from a point of infinite density and zero volume which is the very definition of a singularity?

More concentrated mass would be more correct. Matter is still clumping together. I don't know, but it's fun to think about it.

So you're saying that as the universe expands the matter within it is getting closer to matter in another dimension and the gravitational force is getting stronger? Ok, I can follow that. Interesting idea.

 

[renault314]

A question that I have been wrestling with lately: Matter and energy are essentially the same thing and we can convert matter into energy. If I remember correctly I think that the best hydrogen bombs have about a 1% rate of conversion in turning matter (uranium) into pure energy (massive radiation ie- big explosion) The light from stars comes from hydrogen atoms fusing into helium atoms which gives off various forms of energy (gamma radiation, visible light, microwaves, etc...)

So the inverse of these processes must also be true. Energy must be able to be converted back into matter but I cannot think of an example of this. Can any of you chime in to help me? (or to explain how wrong I am!)

You are super wrong, but don't feel bad, most people are when it comes to this.
The ability to turn energy into matter and matter into energy does not exist and that is not what E=mc2 means. It is a very common misconception. The real implication of this theory is that anytime you gain energy, you gain mass. Anytime you lose energy, you lose mass. One is not converted to the other. When using the sun as an example, the hydrogen fusion reaction causes a massive amount of energy to be released, but another way to say it is that the newly formed helium atom has less energy than the sum of the two hydrogens before it. It has lost so much energy (since it was released in the reaction) that its corresponding drop in mass is measureable. This is the source of the "matter into energy" misconception. The helium does have less mass than the two hydrogen atoms before, but that is because it lost energy and therefore lost mass at a rate proportional to E=mc2.

The reverse can also be seen in nature. A bullet fired out of a gun will have an infinitesimally larger mass than it had when it was just sitting there. Where did this mass come from? from the kinetic energy that was put into the bullet by the expanding gasses doing work on it. The bullet now has more energy, so it has more mass. Again, according to E=mc2 an absolutely enormous amount of energy is needed to gain just a tiny amount of mass.

How much energy? Well, think of like this. In order for a bullet to gain just 10% mass due to its increased velocity (and therefore increased internal energy), it would need to be going about 50% of the speed of light. That's about 450,000,000 fps!

No, a double charge of "power pistol" will not get you there.

Yes, this means that a hot rock weighs more than a cold one of identical starting mass. Yes, it means that one of those disposable cold packs weighs more after you use it that it did before you used it (since it gains energy by absorbing heat which is why it feels cold), it means anything that has more energy weighs more that an identical thing that has less energy.

Hope this helps!

 

[streetroc]

You guys are making some very good points. I knew that most ODT members were smarter than the average bear but I have to say I am really impressed with some of these posts.

By the way I am very disappointed to see that a thread about physics has been moved to the same section as those about big foot sightings and UFOs. Seriously mods...WTF?