# Energy can be conerted into matter

1. Nov 17, 2009

### the_awesome

"Energy can be conerted into matter"

Okay so I'm not scientific genius. Just got a question to ask.
Lets propose that the big bang was correct - the only thing existing before the big bang was energy. Energy gets converted in matter and BAM.
Particle accelerators convert energy into subatomic particles, for example by colliding electrons and positrons. Some of the kinetic energy in the collision goes into creating new particles. However, in the time before the big bang nothing was present. So that means there were no electrons, etc. So if you create matter using electrons then that means nothing can be created without them. So in order for matter to be created at the big bang, electrons would have had to be already present. Isn't that circular reasoning? Can someone please help me better my argument?

2. Nov 17, 2009

### schangtze

Re: "Energy can be conerted into matter"

Well, first, you said that by colliding electrons and positrons,some of the kinetic energy in the collision goes into creating new particles.Is there any proof? I only know that if electrons and positrons collides, nothing left but two photons, which have no rest mass and treated as energy that you're willing to gain.
Secondly, I really do not know what exists before bigbang, because I haven't understand the form of energy's existance.

3. Nov 17, 2009

### the_awesome

Re: "Energy can be conerted into matter"

That was a quote from http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970724a.html

4. Nov 18, 2009

### Staff: Mentor

Re: "Energy can be conerted into matter"

There was no "before the big bang" according to GR. That is like looking at the globe and talking about what is north of the north pole. There is no north of the north pole, in the same way there is no before the big bang.

However, it is expected that GR breaks down near the big bang and that a complete quantum theory of gravity is needed.

5. Nov 18, 2009

### mgb_phys

Re: "Energy can be conerted into matter"

True at low energies, if all you have is a stationary electron and positron at 511kev each then you get a pair of 511kev x-ray photons and the only particles light enough to create with this little energy is a another electron-positron pair.

But if you have a e-/e+ with 200Gev in an accelerator you can make a whole bunch of new particles when they collide

6. Nov 18, 2009

### Bob S

Re: "Energy can be conerted into matter"

Fermilab shoots a beam of protons into a target, produces pairs of protons and anti-protons, collects anti-protons, and accelerates them to about 980 GeV. They store about 1 x 1012 anti-protons in a 6,283-m circumference ring (synchrotron) for up to a day. As long as they do not dump them, they have created and saved extra matter and anti-matter.
Bob S

7. Nov 18, 2009

### the_awesome

Re: "Energy can be conerted into matter"

Okay well I've heard an argument those goes something like this:

What are all the problems with this argument?

As far as I can see....using the equation [e=mc2 ], that there has to be matter present in order for energy to exist. All matter has a mass. So without matter m=0. This means that e=0. Now then, the arguer has said that energy can create matter. Well...we know that we can create matter by colliding electrons and positrons. BUT, electrons and positrons are also matter. So in other words, you need matter to make (more) matter.

Can someone please help me out? Notice that this isn't a hmwk question ;)

Last edited: Nov 19, 2009
8. Nov 18, 2009

### mgb_phys

Re: "Energy can be conerted into matter"

That's not what that equation means

No you create matter out of energy, you can just crash a couple of 511kev x-ray photons together an get an electron-positron pair. it's simply that the most convenient way to produce such x-ray photons in the lab is to collide particles together.

9. Nov 18, 2009

### Bob S

Re: "Energy can be conerted into matter"

Within a few tens of nanoseconds,the positrons stop, find an electron, form positronium, and annihilate. Poof. Gone. The only way to store this extra matter, or to prevent it from annihilating, is to store it in a very high vacuum. Synchrotrons are good storage rings for antimatter.
Bob S

10. Nov 19, 2009

### Staff: Mentor

Re: "Energy can be conerted into matter"

What is the source of this argument? It sounds fairly pseudo-philosophical
Energy does need time and space to exist. Energy is the capacity to do work and work is a force applied over a distance. So without space you don't have a distance over which to apply force and therefore you don't have energy. In fact, even just force requires both space and time as you can clearly see by a simple dimensional analysis.
This is philosophical presupposition. Why is energy required for anything to have a cause? What does "cause" even mean?
The problem with this is that the http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html" [Broken]. What you usually think of as conservation of energy is only globally defined in a special subclass of spacetimes called "static". The universe immediately after the big bang was definitely not static. Also, near the big bang quantum mechanical effects would become important across the entire universe, and we don't yet have a coherent theory of quantum gravity. We simply cannot use our current theoretical tools to justify this statement.

Last edited by a moderator: May 4, 2017
11. Nov 19, 2009

### Staff: Mentor

Re: "Energy can be conerted into matter"

And there was an accelerator at CERN (LEP, the Large Electron Positron collider) that did exactly this from 1988 to 2000.

12. Nov 19, 2009

### the_awesome

13. Nov 19, 2009

### FoxCommander

Re: "Energy can be conerted into matter"

Well to begin, yes energy can be converted into matter. If say you had just pure gamma rays and other sorts of electromagnetic energy in a box eventually these photons would for into a state of symetry, hence matter. The other part of your phylosophy is that no one knows what caused the big bang. There could have been something there before the big bang but no one actually knows. There are many theories as to why. As for the creation of matter in the big bang, it all (energy and matter) of course started as a single point of infinite density. Then something caused it to expand greating space for the energy to move, at this point in time it all was energy because it was way to hot for any particle to remain stable as a state of matter. Then as they cooled they started to form the elementary particles first, quarks and such, then electrons protons and neutrons and then those joined to make hydrogen. Its how most studies have predicted it to happen. As for how the energy in the big bang came into being there are some explinations that when a vacum devoid of matter, when expanded creates energy.
this of course is all my theories as to what i have learned so far. hope it helps
Sincerely FoxCommander

14. Nov 19, 2009

### FoxCommander

Re: "Energy can be conerted into matter"

Um i dont think this is correct. A positron is the "anti" electron, which means it is anti-matter. when those two collide they anihilate each-other, creating pure energy. However, when you collide protons like what they have been trying to do at CERN, then all that kinetic energy goes into breaking up the protons, what is left when they are broken is the basic particles such as quarks and maybe even the Higgs particle(hasn't been found if it exists) a positron and electron collision would result in just energy

15. Nov 19, 2009

### mgb_phys

Re: "Energy can be conerted into matter"

The LHC collies protons at an energy of 7Tev, this is 10,000x the rest mass of the proton so at these energies the proton is pretty much destroyed.
Earlier accelertors (like LEP) used e/e+ mainly for engineering reasons - since they have opposite charges they will go in opposite directions in the same field, so you only need a single beam line.
It's also easier to work at lower energies since you don't need to overcome the electrostatic repulsion - although at LEP / LHC energies this is doesn't matter.
The LHC needs two separate beams of protons in opposite directions with separate magnets.

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