Antimatter - could it ever be utilized as poss. energy source?

[Simfish]

I'm guessing that the amount of energy taken to generate an antimatter particle would always be more than what you would get back by colliding the antimatter generated with a matter particle.

But if we ever find a source of antimatter in the universe, then do you suppose that in the far future, we could utilize antimatter for power?

-T_Simfish

 

[Nenad]

Im not an expert and don't quote me, but I think that the law of conservation of energy plays a part. I think the energy neede to convert a particle into a particle-antiparticle pair is the same as when the pair reunite to form energy.
To answer your second question, the problem with antiparticles is containig them, it is soo hard to contain them, you must use strong magnetic fields. To utalize it for use, I'd say it would take us another meillenium to get there.

 

[Simfish]

Ah, ok. I forgot about the conservation of energy! Thanks for the response! :)

 

[Entropy]

Maybe for spacecraft s but that's about it. You need to create the actual anti-matter first which raises the question, where do you get the energy to create the anti-matter?

 

[Simfish]

where do you get the energy to create the anti-matter?/quote]

And that would have to come only with fusion power plants since antimatter takes up so much energy.

 

[daveed]

hmm... this sounds rather like somerthing from dan brown's Angels and Demons

 

[futb0l]

It will cost a lot of money to produce antimatter... so if there is a new and more efficient way of producing - then maybe we can use it for spacecraft s.

 

[Deeviant]

Anti matter is already created in small quantities in large particle accelerators today, albeit very small quantities. Anti matter would most likely not be used for power generation, but power storage, as its energy density is about as high as possible.

And we already have the ability to store it, at least for relatively small periods of time.

 

[Nenad]

Anti matter is most commonly produced through pair production. When a photon of light has enough energy, it will produce an electron/positron pair. The equation for this is:
$$E_{photon} = mc^2 + mc^2 + E_k$$

the two m's are for the masses of the electron/positron, which are the same. And the $$E_k$$ is the left over kinetic energy as the electron/positron fly apart.

The energy of the photon can be wrotten as:
$$E = hf = \frac{hc}{\lambda}$$
making out final equatin for pair production or antimatter/matter production:

$$\frac{hc}{\lambda} = mc^2 + mc^2 + E_k$$

 

[ArmoSkater87]

The rest mass energy of the electron is .511MeV, in order for electron-positron pair production to be possible, the photon must have an energy of 2(.511) = 1.022MeV. That is the threashhold for creating the pair, and if the energy of the photon is greater than the threashhold, then it adds on to the kinetic energy of the electron and positron after the transformation.

This website should clear everything up for you
http://hyperphysics.phy-astr.gsu.edu/hbase/particles/lepton.html

 

[ArmoSkater87]

I'm guessing that the amount of energy taken to generate an antimatter particle would always be more than what you would get back by colliding the antimatter generated with a matter particle.

You are guessing very right, in fact, if you combined ALL the antimatter ever made at CERN, and if you used that antimatter by anihhilating it with matter, it would give off enough energy to light a light bulb for 3 seconds.

But if we ever find a source of antimatter in the universe, then do you suppose that in the far future, we could utilize antimatter for power?

We probably won't ever use antimatter as a source of energy, I agree with Nenad about how its very hard to contain since it will want to annihilate with its counterpart. The conservation of energy would mean that the energy of the particles when they collide will equal the energy of the annihilation of the antiparticles and particles produced - this is what Nenad was implying. BUT! it also takes a lot energy to create strong magnetic fields in order to accelerate those particles to have such high energy. So...in the long run, you are losing much much more energy than gaining. It is theorized that there are still consentrations of antimatter in the universe left over from the Big Bang, which would give a very sufficial amount of antimatter, but once again, it would be a problem containing it. Although the biggest problem would be geting to it since it will be somewhere very far away from us.

 

[Nenad]

we cannot tell where antimatter is. It will look exackly like matter, not difference but the only diff will be charge. And by the time we find this charge, we will be long gone in a fantastic explosion. For all we know, the Andrometa galaxy could be antimatter.

 

[expscv]

using anitmatter as energy, isn't simmliar to nuclear power which we already have?

 

[russ_watters]

using anitmatter as energy, isn't simmliar to nuclear power which we already have?

Somewhat, yes - and using it to generate power would be trivially simple (simpler even than nuclear power). Collecting it (if we ever found a source) and containing it would be the tough part.

 

[Zeteg]

The conservation of energy would mean that the energy of the particles when they collide will equal the energy of the annihilation of the antiparticles and particles produced

Are you saying that the speed in which matter and anti-matter collide, would affect the energy given?

Anti matter is most commonly produced through pair production. When a photon of light has enough energy, it will produce an electron/positron pair. The equation for this is:

I don't know much about this, so this may seem like a really really stupid question... but: So, you're saying when a matter particle and an anti-matter particle collide, they can create a very small amount of energy? I mean, just as much as a photon in the same direction?

 

[ArmoSkater87]

we cannot tell where antimatter is. It will look exackly like matter, not difference but the only diff will be charge. And by the time we find this charge, we will be long gone in a fantastic explosion. For all we know, the Andrometa galaxy could be antimatter.

Thats very true, which is why scientists are trying to detect heavy anti-atoms coming from deep space, possibly left over after the death of anti-stars in anti-galaxies. The Andromeda is probabaly not made from antimatter since its so close, we would expect anti-galaxies to be much much further, but your right it is possible.

Are you saying that the speed in which matter and anti-matter collide, would affect the energy given?

No, in particle accelerators, particles (proton, neutrons, electrons) are accelerated to almost the speed of light, and then smashed into a target. That smash gives off so much energy that a particle-antiparticle pair are spontaneously produced. I was saying that the energy released from the smash would equal the energy that would be released if the particle and antiparticle were to annihilate each other after creation. They don't have to collide at high speed in order to annihilate, they just have to "touch". Although if they annihilated after colliding at some speed, that adds on to the energy released afterward.

 

[Zeteg]

Ahh, I see. Thanks =)

 

[Vern]

Anti matter is most commonly produced through pair production. When a photon of light has enough energy, it will produce an electron/positron pair. The equation for this is:

I think there must be something else involved, otherwise we would never see photons with more energy than that required to produce an electron-positron pair. Not to mention that if something else were not involved it would falsify a pet theory of mine

Keep on chuggin !

Vern

 

[Nenad]

I don't know much about this, so this may seem like a really really stupid question... but: So, you're saying when a matter particle and an anti-matter particle collide, they can create a very small amount of energy? I mean, just as much as a photon in the same direction?

the photon creates the electron/positron pair, not the other way around. When the photon has enough energy (usualy gamma rays > 1.1MeV) Then an electron/positron pair is formed, and almost instantaineously anniahlated.

 

[Nenad]

I think there must be something else involved, otherwise we would never see photons with more energy than that required to produce an electron-positron pair. Not to mention that if something else were not involved it would falsify a pet theory of mine

Keep on chuggin !

Vern

Yes there is something else involved. Pair production depends on temperatude. If the temperature is <$$10^{9} K$$, then no pair production occurs. If the temp is between $$6*10^{9} K\ to\ 10^{13} K$$ then an electron/positron pair is produced, and if temp is greater than the upper limit, a proton and a antiproton is produced.

 

[Entropy]

Photons have temperture?

 

[russ_watters]

Photons have temperture?

Not exactly, but photons have energy and temperature is a measure of energy. Thus, you can tell the temperature of an object by the color of the light it throws off.

 

[quantumdude]

Yes there is something else involved. Pair production depends on temperatude. If the temperature is <$$10^{9} K$$, then no pair production occurs. If the temp is between $$6*10^{9} K\ to\ 10^{13} K$$ then an electron/positron pair is produced, and if temp is greater than the upper limit, a proton and a antiproton is produced.

I think I get your drift, but the way this is worded can be confusing. When you say "the temperature", I think people could take this to mean "the ambient temperature", which is not right. The determining factor as to whether pair production is "go-or-no-go" is the photon energy. If it is at least as large as 2mc² (where m is the mass of the particle in question) in the lab frame, then you can produce a pair, no matter what the ambient temperature is.

 

[Nenad]

I mean surrounding temp, not temp of a photon.

 

[quantumdude]

Oh yes, and as to the original question, consider the following numerical data.

From a single e⁺e^- annihilation, you get about 1 MeV of energy (from the masses of the two particles). Compare that with the 200 MeV you get for the fission of every ²³⁵U nucleus. Then once you consider that the uranium is available by the kilogram, and positrons are so difficult to store en masse, and you've got quite an engineering problem on your hands. In that respect, the situation would have something in common with fusion power generation: We understand the physics just fine, but we can't get the technology to cooperate with what we know.

 

[quantumdude]

I mean surrounding temp, not temp of a photon.

In that case, what you wrote is not correct. Pairs can be produced in deep space, where the average temperature is about 3 Kelvin.

 

[Nenad]

heres a link, scroll down to pair production. Youll see what I mean: http://instruct1.cit.cornell.edu/courses/astro101/lec32.htm

 

[quantumdude]

heres a link, scroll down to pair production. Youll see what I mean: http://instruct1.cit.cornell.edu/courses/astro101/lec32.htm

OK, I see. The link is discussing the early universe in which there is a "sea" of photons. In an environment in which the universe is awash in radiation, the energy of the radiation field determines the ambient temperature. So in that case, there is a correletion between temperature and pair production. But in a way this hides the real quantity that determines the thresholds for pair production, and that quantity is photon energy.

Today, the universe is awash in weak radiation (with a temp of about 3K, as I said). As is known from QFT and from experiment, pair production is a quantum phenomenon, and as such it only takes a single photon to produce a pair in the Coulomb field of a heavy nucleus. It is the energy of this single photon that determines the thresholds for pair production, and it does not matter what the surrounding temperature is.

 

[Nenad]

Im just stationg what the site says. I trust Cornell, theyre a good university. But you do have a point.

 

[quantumdude]

Im just stationg what the site says. I trust Cornell, theyre a good university. But you do have a point.

To be sure, Cornell is trustworthy. But that site is meant to be a layperson's introduction to the early universe, not a tutorial on particle physics.

 

[alexkerhead]

Maybe for spacecraft s but that's about it. You need to create the actual anti-matter first which raises the question, where do you get the energy to create the anti-matter?

But wouldn't the anti-matter react negatively to the matter?

 

[ArmoSkater87]

But wouldn't the anti-matter react negatively to the matter?

Im not sure what you mean by "react negatively" but matter and antimatter annihilate each other when they touch, in other words they get converted completely into energy. So, we WANT them to "react" with each other, because the energy relased from it is a very good prepelant for spaceships if we had a sufficient quantity of antimatter. If we eventually make antimatter propeled spaceships, we could reach to almost the speed of light.

Today, the universe is awash in weak radiation (with a temp of about 3K, as I said). As is known from QFT and from experiment, pair production is a quantum phenomenon, and as such it only takes a single photon to produce a pair in the Coulomb field of a heavy nucleus. It is the energy of this single photon that determines the thresholds for pair production, and it does not matter what the surrounding temperature is.

I was wondering...how come its possible for ONE photon to get converted into an electron-positron pair, while when the electron-positron pair annihilate, they are ALWAYS converted into TWO gamma rays with equal energy in opposite direction, in order to conserve energy and momentum. Doesnt the fact that one photon can be converted into the pair in a sense violate conservation of momentum?

 

[quantumdude]

I was wondering...how come its possible for ONE photon to get converted into an electron-positron pair, while when the electron-positron pair annihilate, they are ALWAYS converted into TWO gamma rays with equal energy in opposite direction, in order to conserve energy and momentum. Doesnt the fact that one photon can be converted into the pair in a sense violate conservation of momentum?

Yes it does, and that's why the photon does not create a pair all by itself. Pair production from a single photon is done in the presence of a Coulomb field, often that due to a heavy nucleus. The nucleus recoils after the production, and so is able to conserve both energy and momentum in the process.

 

[alexkerhead]

Im not sure what you mean by "react negatively" but matter and antimatter annihilate each other when they touch, in other words they get converted completely into energy. So, we WANT them to "react" with each other, because the energy relased from it is a very good prepelant for spaceships if we had a sufficient quantity of antimatter. If we eventually make antimatter propeled spaceships, we could reach to almost the speed of light.

Thanks for the clear up...
I see now..
I was really under the close minded impression that when they reacted, they would disappear..lol

I understand, thanks for clearing it up..

But the idea has been around for decades..
If we could develope an efficient way of space travel, anti-matter could be found, but would be hard to collect and manage..

 

[ArmoSkater87]

Thanks for the clear up...
I see now..
I was really under the close minded impression that when they reacted, they would disappear..lol

Thats why everything that happens must obey the conservation laws . If they disapeared without geting converted into anything, that would violate the conservation of mass and energy, E=mc^2. Momentum must be conserved as well, which is why then regular and anti particles annihilate to create 2 gamma rays going in opposite directions.

If they just I understand, thanks for clearing it up..

But the idea has been around for decades..
If we could develope an efficient way of space travel, anti-matter could be found, but would be hard to collect and manage..

People are trying to detect anti-atoms now as a sign of anti-stars, but havnt found any. Which means that they either don't exist (not likely), or they are extreamly far. Even at the speed of light, it would take too long to get there, let alone collect and contain it, and then bring it back.