Sir, we have a antimatter containment breach on deck 10!!!
November 18, 2010 9:52 AM Subscribe
Antimatter atoms produced and trapped at CERN
The ALPHA experiment at CERN has taken an important step forward in developing techniques to understand one of the Universe’s open questions: is there a difference between matter and antimatter? In a paper published in Nature today, the collaboration shows that it has successfully produced and trapped atoms of antihydrogen. This development opens the path to new ways of making detailed measurements of antihydrogen, which will in turn allow scientists to compare matter and antimatter. (previously)
The ALPHA experiment at CERN has taken an important step forward in developing techniques to understand one of the Universe’s open questions: is there a difference between matter and antimatter? In a paper published in Nature today, the collaboration shows that it has successfully produced and trapped atoms of antihydrogen. This development opens the path to new ways of making detailed measurements of antihydrogen, which will in turn allow scientists to compare matter and antimatter. (previously)
This is so cool.
posted by Zozo at 9:53 AM on November 18, 2010 [1 favorite]
posted by Zozo at 9:53 AM on November 18, 2010 [1 favorite]
Forgot to add:
Jeffery Hangst, spokesman and researcher for the ALPHA experiment, explains.
posted by AElfwine Evenstar at 9:55 AM on November 18, 2010 [1 favorite]
Jeffery Hangst, spokesman and researcher for the ALPHA experiment, explains.
posted by AElfwine Evenstar at 9:55 AM on November 18, 2010 [1 favorite]
By my calculations, only about 417,000,000,000,000 more antihydrogen atoms to go before they have the energy equivalent of a teaspoon of sugar.
But seriously, a good day for science.
posted by jedicus at 9:56 AM on November 18, 2010
But seriously, a good day for science.
posted by jedicus at 9:56 AM on November 18, 2010
I thought something felt different.
posted by vverse23 at 9:56 AM on November 18, 2010 [1 favorite]
posted by vverse23 at 9:56 AM on November 18, 2010 [1 favorite]
Can someone like significantly dumb it down for the English majors who love science but don't have the background?
posted by nevercalm at 9:57 AM on November 18, 2010 [12 favorites]
posted by nevercalm at 9:57 AM on November 18, 2010 [12 favorites]
Anti-matter is like matter, only the opposite. Also, if they touch each other there's a ginormous explosion.
posted by DU at 9:59 AM on November 18, 2010 [1 favorite]
posted by DU at 9:59 AM on November 18, 2010 [1 favorite]
They're going to wind up getting us all killed. Aren't they.
posted by notmydesk at 9:59 AM on November 18, 2010 [1 favorite]
posted by notmydesk at 9:59 AM on November 18, 2010 [1 favorite]
Anti-matter is like matter, only the opposite. Also, if they touch each other there's a ginormous explosion.
Can someone smarten it up for the English majors who love science but don't have the background?
posted by nevercalm at 10:00 AM on November 18, 2010 [24 favorites]
Can someone smarten it up for the English majors who love science but don't have the background?
posted by nevercalm at 10:00 AM on November 18, 2010 [24 favorites]
How exactly does one trap antimatter? I assume using gravitational fields in a vacuum or something, as a matter bottle would explode on contact.
posted by msbutah at 10:00 AM on November 18, 2010
posted by msbutah at 10:00 AM on November 18, 2010
If we're going to trap it, I guess it's more ethical that we do so to antimatter which we've created ourselves.
posted by Joe Beese at 10:01 AM on November 18, 2010 [7 favorites]
posted by Joe Beese at 10:01 AM on November 18, 2010 [7 favorites]
Anti-matter is like matter, but with an evil moustache.
posted by Blazecock Pileon at 10:01 AM on November 18, 2010 [34 favorites]
posted by Blazecock Pileon at 10:01 AM on November 18, 2010 [34 favorites]
I bet it involves a Bose-Einstein Condensate. Everything cool that's happened in science in the last ten years seems to involve a Bose-Einstein Condensate.
posted by griphus at 10:01 AM on November 18, 2010 [3 favorites]
posted by griphus at 10:01 AM on November 18, 2010 [3 favorites]
Can someone like significantly dumb it down for the English majors who love science but don't have the background?
If Shakespeare ran into his anti-Shakespeare at a posh party at ye ol' Brew Pub and shook his hand then there's be no Shakespeare, or anti-Shakespeare for that matter. They both would have existed though, so history is not rewritten.
posted by zombieApoc at 10:02 AM on November 18, 2010 [6 favorites]
If Shakespeare ran into his anti-Shakespeare at a posh party at ye ol' Brew Pub and shook his hand then there's be no Shakespeare, or anti-Shakespeare for that matter. They both would have existed though, so history is not rewritten.
posted by zombieApoc at 10:02 AM on November 18, 2010 [6 favorites]
Looking forward to the obvious next step: CAM bombardments of enemy Orbitals from our Ocean class GSVs.
posted by drinkcoffee at 10:02 AM on November 18, 2010 [6 favorites]
posted by drinkcoffee at 10:02 AM on November 18, 2010 [6 favorites]
How exactly does one trap antimatter? I assume using gravitational fields in a vacuum or something, as a matter bottle would explode on contact.
Magnets!
posted by empath at 10:02 AM on November 18, 2010
Magnets!
posted by empath at 10:02 AM on November 18, 2010
I wouldn't worry about anti-matter explosions.
The Joker: See, I'm a man of simple tastes. I like dynamite and gunpowder and gasoline. Do you know what all these things have in common? They're cheap.
posted by Cool Papa Bell at 10:02 AM on November 18, 2010 [1 favorite]
The Joker: See, I'm a man of simple tastes. I like dynamite and gunpowder and gasoline. Do you know what all these things have in common? They're cheap.
posted by Cool Papa Bell at 10:02 AM on November 18, 2010 [1 favorite]
Will there be anti-bacon?
posted by Hairy Lobster at 10:03 AM on November 18, 2010
posted by Hairy Lobster at 10:03 AM on November 18, 2010
How exactly does one trap antimatter?
Very very carefully.
More seriously, I think generally electromagnetic fields are used.
From the first link:
Very very carefully.
More seriously, I think generally electromagnetic fields are used.
From the first link:
Antihydrogen atoms are produced in a vacuum at CERN, but are nevertheless surrounded by normal matter. Because matter and antimatter annihilate when they meet, the antihydrogen atoms have a very short life expectancy. This can be extended, however, by using strong and complex magnetic fields to trap them and thus prevent them from coming into contact with matter. The ALPHA experiment has shown that it is possible to hold on to atoms of antihydrogen in this way for about a tenth of a second: easily long enough to study them. Of the many thousands of antiatoms the experiment has created, ALPHA’s latest paper reports that 38 have been trapped for long enough to study.posted by kmz at 10:04 AM on November 18, 2010 [1 favorite]
If Shakespeare ran into his anti-Shakespeare at a posh party at ye ol' Brew Pub and shook his hand then there's be no Shakespeare, or anti-Shakespeare for that matter. They both would have existed though, so history is not rewritten.
I dunno, that giant crater where northwestern Europe used to be would have probably changed things a bit.
posted by kmz at 10:06 AM on November 18, 2010
I dunno, that giant crater where northwestern Europe used to be would have probably changed things a bit.
posted by kmz at 10:06 AM on November 18, 2010
Oddly enough, it is chemically identical to Four Loko.
posted by brain_drain at 10:06 AM on November 18, 2010 [12 favorites]
posted by brain_drain at 10:06 AM on November 18, 2010 [12 favorites]
anti-Shakespeare's plays are all like Hamlet: The well-adjucted King to Be, MacBeth: A Comedy Of Manners. and the sedate Midsummer's Night Tea Party.
posted by The Whelk at 10:08 AM on November 18, 2010 [6 favorites]
posted by The Whelk at 10:08 AM on November 18, 2010 [6 favorites]
Will there be anti-bacon?
Anti-Bacon actually wrote the plays attributed to anti-Shakespeare.
posted by Joe Beese at 10:10 AM on November 18, 2010 [82 favorites]
Anti-Bacon actually wrote the plays attributed to anti-Shakespeare.
posted by Joe Beese at 10:10 AM on November 18, 2010 [82 favorites]
I feel safe in predicting that at some point in the future this knowledge will be used in new and creative ways to kill poor people with powerful weapons.
posted by milarepa at 10:11 AM on November 18, 2010 [7 favorites]
posted by milarepa at 10:11 AM on November 18, 2010 [7 favorites]
How exactly does one trap antimatter? ...
Magnets!
How the fuck does THAT work?
posted by ROU_Xenophobe at 10:12 AM on November 18, 2010 [14 favorites]
Magnets!
How the fuck does THAT work?
posted by ROU_Xenophobe at 10:12 AM on November 18, 2010 [14 favorites]
I wonder if the anti-matter me is posting to an anti-matter metafilter, I wonder what the anti-metafilter is like? Can I trap it in a magnetic field and post to it?
Can I trap the anti-me In a magnetic field and kill him? I don't like the thought that he is out there somewhere posting on the anti-metafilter about trapping and killing me. I've got to get him first.
posted by Ad hominem at 10:12 AM on November 18, 2010 [6 favorites]
Can I trap the anti-me In a magnetic field and kill him? I don't like the thought that he is out there somewhere posting on the anti-metafilter about trapping and killing me. I've got to get him first.
posted by Ad hominem at 10:12 AM on November 18, 2010 [6 favorites]
By my calculations, only about 417,000,000,000,000 more antihydrogen atoms to go before they have the energy equivalent of a teaspoon of sugar.
I have 2.22476838 × 10^11 if they only captured one atom.
mass of hydrogen atom: 1.67400 * (10^(-27) kg
2 * 1.67400 * (10^(-27)) kg * (c^2) = 7.19175989 × 10^-11 calories (Energy released when an anti-hydrogen and hydrogen atom collide)
16 calories in a teaspoon of sugar.
16/(7.19175989 × 10^-11)
2.22476838 × 10^11
posted by empath at 10:13 AM on November 18, 2010
I have 2.22476838 × 10^11 if they only captured one atom.
mass of hydrogen atom: 1.67400 * (10^(-27) kg
2 * 1.67400 * (10^(-27)) kg * (c^2) = 7.19175989 × 10^-11 calories (Energy released when an anti-hydrogen and hydrogen atom collide)
16 calories in a teaspoon of sugar.
16/(7.19175989 × 10^-11)
2.22476838 × 10^11
posted by empath at 10:13 AM on November 18, 2010
How exactly does one trap antimatter
Antimatter can have a charge, like matter (but opposite -- anti-electrons aka positrons have a positive charge and anti-protons have a negative charge.) So if you have charged antimatter, you can keep it contained a with magnetic field.
But a complete antihydrogen atom has a neutral charge, and can't be magnetically contained. If I'm reading the abstract (and some supporting material) right, that's their proof that they've succeeded in creating antihydrogen -- it's escaping the magnetic trap and colliding destructively with the container walls. (A macroscopic amount of antimatter contacting a macroscopic amount of matter would create a ginormous explosion. But a single atom of antihydrogen produces a very tiny explosion.)
posted by Zed at 10:18 AM on November 18, 2010
Antimatter can have a charge, like matter (but opposite -- anti-electrons aka positrons have a positive charge and anti-protons have a negative charge.) So if you have charged antimatter, you can keep it contained a with magnetic field.
But a complete antihydrogen atom has a neutral charge, and can't be magnetically contained. If I'm reading the abstract (and some supporting material) right, that's their proof that they've succeeded in creating antihydrogen -- it's escaping the magnetic trap and colliding destructively with the container walls. (A macroscopic amount of antimatter contacting a macroscopic amount of matter would create a ginormous explosion. But a single atom of antihydrogen produces a very tiny explosion.)
posted by Zed at 10:18 AM on November 18, 2010
Here's some more detail for nevercalm. Every kind of sub-atomic particle has an anti-particle which is, in some way, its opposite (although photons are considered to be their own anti-particles). Particles have the same mass as their anti-particles (anti-matter is not negative matter!) but often have an opposte charge, as with, for example, the electron, with a charge of -1, and the positron, with a charge of +1. If a particle (such as a neutron) does not have a charge, then the anti-particle differs in terms of spin (incidentally, although it is believed that sub-atomic particles actually do spin, somwhat in the way that the planet Earth spins, it is a very different kind of spin due to quantum mechanical considerations; there is only one possible speed for the spin of a sub-atomic particle, and two possible directions, and if a particle is the kind that spins, it always spins, because spin is an intrinsic property of that particle). Charge and spin are the only variables which distinguish particles from their own anti-particles. (This is also why photons are their own anti-particle; they have neither charge nor spin.)
An atom of hydrogen (as you probably know!) consists of one proton in the center, orbited by one electron. Those are both particles. Their anti-particles are the anti-proton and the positron. So an atom of anti-hydrogen consists of an anti-proton in the center, orbited by a positron. It weighs exactly the same as an atom of hydrogen. Both the atom and the anti-atom are electrically neutral, but with the atom, there is a positive charge in the center and a negative charge on the outer perimeter; with an anti-atom, there is a negative charge in the center and a positive charge on the outer perimeter. OK?
posted by grizzled at 10:18 AM on November 18, 2010 [8 favorites]
An atom of hydrogen (as you probably know!) consists of one proton in the center, orbited by one electron. Those are both particles. Their anti-particles are the anti-proton and the positron. So an atom of anti-hydrogen consists of an anti-proton in the center, orbited by a positron. It weighs exactly the same as an atom of hydrogen. Both the atom and the anti-atom are electrically neutral, but with the atom, there is a positive charge in the center and a negative charge on the outer perimeter; with an anti-atom, there is a negative charge in the center and a positive charge on the outer perimeter. OK?
posted by grizzled at 10:18 AM on November 18, 2010 [8 favorites]
So...what does this all mean and what are the possible implications of it all?
posted by nomadicink at 10:21 AM on November 18, 2010
posted by nomadicink at 10:21 AM on November 18, 2010
Can someone smarten it up for the English majors who love science but don't have the background?
Allow me to be the snarkparty pooper.
Most elementary particles have a positive or negative electric charge. An electron has a negative charge. A proton has a positive charge. It is possible for these particles to have these charges reversed, but we never see this in nature. That kind of matter is called antimatter.
We can create antimatter in colliders. When a particle comes in contact with its antiparticle they both turn into light. This is the only known way to convert matter into energy with no matter left over.
Why there is only matter in the universe, and no antimatter, is one of the great mysteries of physics.
posted by clarknova at 10:23 AM on November 18, 2010 [4 favorites]
Allow me to be the snarkparty pooper.
Most elementary particles have a positive or negative electric charge. An electron has a negative charge. A proton has a positive charge. It is possible for these particles to have these charges reversed, but we never see this in nature. That kind of matter is called antimatter.
We can create antimatter in colliders. When a particle comes in contact with its antiparticle they both turn into light. This is the only known way to convert matter into energy with no matter left over.
Why there is only matter in the universe, and no antimatter, is one of the great mysteries of physics.
posted by clarknova at 10:23 AM on November 18, 2010 [4 favorites]
16 calories in a teaspoon of sugar.
16 kilocalories.
16000/(7.19175989 × 10-11) = 2.2 × 1014 atoms
Pedantic, couldn't resist. Desperately trying to procrastinate.
posted by kiltedtaco at 10:23 AM on November 18, 2010 [3 favorites]
16 kilocalories.
16000/(7.19175989 × 10-11) = 2.2 × 1014 atoms
Pedantic, couldn't resist. Desperately trying to procrastinate.
posted by kiltedtaco at 10:23 AM on November 18, 2010 [3 favorites]
You can also tell the positrons from the electrons by their little beards.
posted by bonehead at 10:23 AM on November 18, 2010 [1 favorite]
posted by bonehead at 10:23 AM on November 18, 2010 [1 favorite]
Antimatter atoms produced and trapped at CERN
What, no photos?
posted by nickmark at 10:25 AM on November 18, 2010
What, no photos?
posted by nickmark at 10:25 AM on November 18, 2010
Anti-matter is like matter, but with an evil moustache goatee.
posted by entropicamericana at 10:28 AM on November 18, 2010 [4 favorites]
posted by entropicamericana at 10:28 AM on November 18, 2010 [4 favorites]
The big deal here is that this paves the way for all kinds of interesting experiments on anti-atoms. The radiation spectrum of normal hydrogen has been thoroughly checked against quantum mechanical predictions, and according to the Standard Model, antihydrogen should look exactly the same. But because antimatter gets annihilated so quickly, there's never been a way to actually measure its properties in enough detail to confirm this.
posted by teraflop at 10:29 AM on November 18, 2010 [1 favorite]
posted by teraflop at 10:29 AM on November 18, 2010 [1 favorite]
What, no photos?
I imagine it would be as transparent as regular hydrogen.
posted by empath at 10:31 AM on November 18, 2010
I imagine it would be as transparent as regular hydrogen.
posted by empath at 10:31 AM on November 18, 2010
Can I trap the anti-me In a magnetic field and kill him? I don't like the thought that he is out there somewhere posting on the anti-metafilter about trapping and killing me. I've got to get him first.
posted by Ad hominem at 10:12 AM on November 18
Epon... you know what, never mind...
posted by yeloson at 10:31 AM on November 18, 2010 [2 favorites]
posted by Ad hominem at 10:12 AM on November 18
Epon... you know what, never mind...
posted by yeloson at 10:31 AM on November 18, 2010 [2 favorites]
How exactly does one trap anti-hydrogen
Really really cold temperatures and magnets
Really really cold temperatures and magnets
At this point, there is a problem: the antihydrogen is chargeless and can no longer be contained in the magnetic Penning trap. The researchers constructed what they called an ALPHA apparatus, which features a novel superconducting magnetic trap that interacts with the antihydrogen's magnetic moment. The magnetic moment of an individual atom comes from the structure or interaction of the orbiting particle (the positron) and the nucleus (the antiproton) and allows the particle to interact with electric fields in a weak manner. The ALPHA trap can confine antihydrogen in the ground state if it's kept at temperatures of less than half a Kelvin.posted by SirOmega at 10:32 AM on November 18, 2010 [2 favorites]
Every type of elementary particle has an anti-matter equivalent: electrons have positrons, quarks have anti-quarks, etc. Some particles are their own anti-particles, ie, a photon is the anti-particle of the photon.
Discovering the anti-particles was (relatively) easy: they get produced all the time (especially in particle colliders), they just don't last very long because once they interact with their normal-matter equivalent, they annihilate into a photon.
Making an anti-matter atom is a lot trickier, since you have to make 3 anti-matter quarks, and get them to bond together before they come into contact with any regular matter, then get a positron to orbit around them. This has been done before, but only at very high energies, which means that the anti-hydrogen is produced, then almost instantly shoots off and annihilates with something else.
What ALPHA managed to do was slow down and trap the anti-Hydrogen, so that the can be studied. This is important.
One of the biggest problems in Physics and Astronomy these days is Baryon Asymmetry. Big Bang theory predicts that matter and anti-matter should be created in equal amounts at the start of the universe, and basic particle physics predicts that each matter particle would annihilate with an anti-matter particle and there would be nothing left in the Universe. This is known as CP-symmetry. Obviously this is a problem. CP-symmetry implies that matter and anti-matter are exact charge reversed mirror images of each other. In modern particle physics, we've found some examples of CP violation (CPV). This is good, because it shows an asymmetry between matter and anti-matter. But the CPV that's been discovered is not enough to explain why there's so much matter left over from the Big Bang.
By making and trapping anti-Hydrogen, we can compare its properties to normal Hydrogen, which we understand very well since we've been studying it for a century. Any differences will point us in the direction of where to find more CP violation, and help us construct theories to explain it.
For those interested, the real symmetry between matter and anti-matter is thought to be CPT symmetry. This means charge reversal, mirror image and time reversal.
posted by auto-correct at 10:33 AM on November 18, 2010 [16 favorites]
Discovering the anti-particles was (relatively) easy: they get produced all the time (especially in particle colliders), they just don't last very long because once they interact with their normal-matter equivalent, they annihilate into a photon.
Making an anti-matter atom is a lot trickier, since you have to make 3 anti-matter quarks, and get them to bond together before they come into contact with any regular matter, then get a positron to orbit around them. This has been done before, but only at very high energies, which means that the anti-hydrogen is produced, then almost instantly shoots off and annihilates with something else.
What ALPHA managed to do was slow down and trap the anti-Hydrogen, so that the can be studied. This is important.
One of the biggest problems in Physics and Astronomy these days is Baryon Asymmetry. Big Bang theory predicts that matter and anti-matter should be created in equal amounts at the start of the universe, and basic particle physics predicts that each matter particle would annihilate with an anti-matter particle and there would be nothing left in the Universe. This is known as CP-symmetry. Obviously this is a problem. CP-symmetry implies that matter and anti-matter are exact charge reversed mirror images of each other. In modern particle physics, we've found some examples of CP violation (CPV). This is good, because it shows an asymmetry between matter and anti-matter. But the CPV that's been discovered is not enough to explain why there's so much matter left over from the Big Bang.
By making and trapping anti-Hydrogen, we can compare its properties to normal Hydrogen, which we understand very well since we've been studying it for a century. Any differences will point us in the direction of where to find more CP violation, and help us construct theories to explain it.
For those interested, the real symmetry between matter and anti-matter is thought to be CPT symmetry. This means charge reversal, mirror image and time reversal.
posted by auto-correct at 10:33 AM on November 18, 2010 [16 favorites]
Live action footage from Switzerland!
posted by The 10th Regiment of Foot at 10:34 AM on November 18, 2010
posted by The 10th Regiment of Foot at 10:34 AM on November 18, 2010
The big deal here is that this paves the way for all kinds of interesting experiments on anti-atoms.
Okaaaay, what sort of interesting experiments?
posted by nomadicink at 10:36 AM on November 18, 2010
Okaaaay, what sort of interesting experiments?
posted by nomadicink at 10:36 AM on November 18, 2010
Okaaaay, what sort of interesting experiments?
I don't know too much about ALPHA specifically, but I assume at first they won't be doing anything too exciting. First off is measuring the atomic spectrum to compare it to normal Hydrogen. They also mention in the abstract that they want to look at how gravity acts on anti-Hydrogen. I think most people assume that gravity wouldn't differentiate between matter and anti-matter, but because of the way anti-matter is usually produced, there's been no way to check this experimentally.
posted by auto-correct at 10:43 AM on November 18, 2010
I don't know too much about ALPHA specifically, but I assume at first they won't be doing anything too exciting. First off is measuring the atomic spectrum to compare it to normal Hydrogen. They also mention in the abstract that they want to look at how gravity acts on anti-Hydrogen. I think most people assume that gravity wouldn't differentiate between matter and anti-matter, but because of the way anti-matter is usually produced, there's been no way to check this experimentally.
posted by auto-correct at 10:43 AM on November 18, 2010
What, no photos?
here
Thanks! So the one on the left is the anti-hydrogen, right?
No, seriously though, thanks.
posted by nickmark at 10:44 AM on November 18, 2010
here
Thanks! So the one on the left is the anti-hydrogen, right?
No, seriously though, thanks.
posted by nickmark at 10:44 AM on November 18, 2010
(Anti-)MatterFilter.
posted by ZenMasterThis at 10:44 AM on November 18, 2010
posted by ZenMasterThis at 10:44 AM on November 18, 2010
The big deal here is that this paves the way for all kinds of interesting experiments on anti-atoms.
Okaaaay, what sort of interesting experiments?
Anti-baking-soda volcanoes. (After they make enough anti-paper-maché.)
posted by PlusDistance at 10:47 AM on November 18, 2010 [2 favorites]
Okaaaay, what sort of interesting experiments?
Anti-baking-soda volcanoes. (After they make enough anti-paper-maché.)
posted by PlusDistance at 10:47 AM on November 18, 2010 [2 favorites]
I have 2.22476838 × 10^11 if they only captured one atom.
Yeah, as kiltedtaco points out, the Calories in food are kilocalories. The rest of it is (roughly) a factor of 2 difference because I accidentally double-counted the energy in the matter/antimatter combination. Anyway, the point was just that, although this is very interesting research, we would need a fundamentally different way of producing antimatter for it to be at all practical as a way of storing energy.
posted by jedicus at 10:47 AM on November 18, 2010
Yeah, as kiltedtaco points out, the Calories in food are kilocalories. The rest of it is (roughly) a factor of 2 difference because I accidentally double-counted the energy in the matter/antimatter combination. Anyway, the point was just that, although this is very interesting research, we would need a fundamentally different way of producing antimatter for it to be at all practical as a way of storing energy.
posted by jedicus at 10:47 AM on November 18, 2010
For those interested, the real symmetry between matter and anti-matter is thought to be CPT symmetry. This means charge reversal, mirror image and time reversal.
Which leads to all kinds of possible wackiness. Is anti-matter like regular matter, just travelling backwards in time? Feynman's diagrams would have it so. Would an anti-matter universe run backwards compared to our own?
Possibly not, but still, this is why these experiments need to be done.
The moral of this story is: don't shake hands with a time traveller.
posted by bonehead at 10:56 AM on November 18, 2010 [4 favorites]
Which leads to all kinds of possible wackiness. Is anti-matter like regular matter, just travelling backwards in time? Feynman's diagrams would have it so. Would an anti-matter universe run backwards compared to our own?
Possibly not, but still, this is why these experiments need to be done.
The moral of this story is: don't shake hands with a time traveller.
posted by bonehead at 10:56 AM on November 18, 2010 [4 favorites]
They're waiting for you Gordon... In the test chamber.
posted by Babblesort at 11:02 AM on November 18, 2010 [6 favorites]
posted by Babblesort at 11:02 AM on November 18, 2010 [6 favorites]
From 1956:
Well beyond the tropstrata
There is a region stark and stellar
Where, on a streak of anti-matter
Lived Dr. Edward anti-Teller.
Remote from Fusion's origin,
He lived unguessed and unawares
With all his antikith and kin,
And kept macassars on his chairs.
One morning, idling by the sea,
He spied a tin of monstrous girth
That bore three letters: A. E. C.
Out stepped a visitor from Earth.
Then, shouting gladly o'er the sands,
Met two who in their alien ways
Were like as lentils. Their right hands
Clasped, and the rest was gamma rays.
— Harold P. Furth
In 'Perils of Modern Living', The New Yorker (10 Nov 1956), 56.
posted by jamjam at 11:04 AM on November 18, 2010 [3 favorites]
Well beyond the tropstrata
There is a region stark and stellar
Where, on a streak of anti-matter
Lived Dr. Edward anti-Teller.
Remote from Fusion's origin,
He lived unguessed and unawares
With all his antikith and kin,
And kept macassars on his chairs.
One morning, idling by the sea,
He spied a tin of monstrous girth
That bore three letters: A. E. C.
Out stepped a visitor from Earth.
Then, shouting gladly o'er the sands,
Met two who in their alien ways
Were like as lentils. Their right hands
Clasped, and the rest was gamma rays.
— Harold P. Furth
In 'Perils of Modern Living', The New Yorker (10 Nov 1956), 56.
posted by jamjam at 11:04 AM on November 18, 2010 [3 favorites]
They're going to wind up getting us all killed. Aren't they.
Don't worry. We already know how the Universe ends. Some Tralfamadorian scientists mess up testing a new rocket fuel some billions of years from now.
posted by philip-random at 11:05 AM on November 18, 2010 [2 favorites]
Don't worry. We already know how the Universe ends. Some Tralfamadorian scientists mess up testing a new rocket fuel some billions of years from now.
posted by philip-random at 11:05 AM on November 18, 2010 [2 favorites]
Why don't they just wink out? 1+(-1)=0
Instead, we get energy.
posted by Xoebe at 11:14 AM on November 18, 2010
Instead, we get energy.
posted by Xoebe at 11:14 AM on November 18, 2010
But a single atom of antihydrogen produces a very tiny explosion.
Here I am picturing the world's tiniest mushroom cloud with a dumb grin on my face.
I
posted by quin at 11:25 AM on November 18, 2010
Here I am picturing the world's tiniest mushroom cloud with a dumb grin on my face.
I
[heart] science, even when I don't fully understand the math.posted by quin at 11:25 AM on November 18, 2010
I know that people probably don't understand this very well, but I figure it can't hurt to ask...
Is there any problem where people have been like X is impossible... but not if we could reliably produce antimatter? Obviously there's a difference between capturing and observing a small bit of it, and reliably making a lot of it, but are there any guesses as to practical applications yet?
posted by codacorolla at 11:26 AM on November 18, 2010
Is there any problem where people have been like X is impossible... but not if we could reliably produce antimatter? Obviously there's a difference between capturing and observing a small bit of it, and reliably making a lot of it, but are there any guesses as to practical applications yet?
posted by codacorolla at 11:26 AM on November 18, 2010
Will there be anti-bacon?
I've been anti-Bacon every since I saw Hollow Man.
posted by ChipT at 11:33 AM on November 18, 2010 [2 favorites]
I've been anti-Bacon every since I saw Hollow Man.
posted by ChipT at 11:33 AM on November 18, 2010 [2 favorites]
Why don't they just wink out? 1+(-1)=0
Conservation of mass and energy, basically. Mass and energy are equivalent, as Einstein showed, and neither can be created or destroyed, just transformed from one to the other or from one form to another (e.g. nuclear fission and fusion, changing electrical energy into light via a light bulb).
Is there any problem where people have been like X is impossible... but not if we could reliably produce antimatter?
Oh yeah. If we could reliably, safely produce and store antimatter we could use it as an amazingly dense fuel for spaceships. By far the biggest part of the weight in a spaceship is the fuel, especially for the takeoff. With antimatter you can get an energy density over 10,000 times that of a nuclear fission reactor and over a 100 times that even of fusion. Millions of times better than chemical fuels.
posted by jedicus at 11:33 AM on November 18, 2010 [1 favorite]
Conservation of mass and energy, basically. Mass and energy are equivalent, as Einstein showed, and neither can be created or destroyed, just transformed from one to the other or from one form to another (e.g. nuclear fission and fusion, changing electrical energy into light via a light bulb).
Is there any problem where people have been like X is impossible... but not if we could reliably produce antimatter?
Oh yeah. If we could reliably, safely produce and store antimatter we could use it as an amazingly dense fuel for spaceships. By far the biggest part of the weight in a spaceship is the fuel, especially for the takeoff. With antimatter you can get an energy density over 10,000 times that of a nuclear fission reactor and over a 100 times that even of fusion. Millions of times better than chemical fuels.
posted by jedicus at 11:33 AM on November 18, 2010 [1 favorite]
AM bombs could make nuclear bombs look like fireworks. 1 g of AM is the same as 42 kt of dynamite. In theory, with clever containment, an Hiroshima-calibre bomb could be the size of a tennis ball.
It could be a really mass-efficient rocket fuel. while hugely energy inefficient to make, AM might be necessary to allow for practical (reasonable time) travel within our solar system.
It's already in use as a medical imaging technology.
posted by bonehead at 11:36 AM on November 18, 2010 [3 favorites]
It could be a really mass-efficient rocket fuel. while hugely energy inefficient to make, AM might be necessary to allow for practical (reasonable time) travel within our solar system.
It's already in use as a medical imaging technology.
posted by bonehead at 11:36 AM on November 18, 2010 [3 favorites]
In answer to this question:
Why don't they just wink out? 1+(-1)=0
Instead, we get energy.
posted by Xoebe
Anti-matter is, technically, a form of matter. The term anti-matter does not mean negative matter. The weight of one negatively charged electron plus its anti-particle, a positively charged positron, is the same as the weight of two electrons, or equally well, the weight of two positrons. The charges do balance, however, so that the negative charge of the electron, added to the positive charge of the positron, equals no electrical charge. But it's the matter, not the charge, that gets converted into energy.
posted by grizzled at 11:37 AM on November 18, 2010 [1 favorite]
Why don't they just wink out? 1+(-1)=0
Instead, we get energy.
posted by Xoebe
Anti-matter is, technically, a form of matter. The term anti-matter does not mean negative matter. The weight of one negatively charged electron plus its anti-particle, a positively charged positron, is the same as the weight of two electrons, or equally well, the weight of two positrons. The charges do balance, however, so that the negative charge of the electron, added to the positive charge of the positron, equals no electrical charge. But it's the matter, not the charge, that gets converted into energy.
posted by grizzled at 11:37 AM on November 18, 2010 [1 favorite]
Oh yeah. If we could reliably, safely produce and store antimatter we could use it as an amazingly dense fuel for spaceships. By far the biggest part of the weight in a spaceship is the fuel, especially for the takeoff. With antimatter you can get an energy density over 10,000 times that of a nuclear fission reactor and over a 100 times that even of fusion. Millions of times better than chemical fuels.
So, then, the problem becomes how much energy it takes to create antimatter, right? If it takes thousands of coal firing plants years to make a spaceship's payload worth of fuel, then it's not really worth the time (unless, maybe, it was some Ark-like last ditch solution to climate change, or a deep space impact).
posted by codacorolla at 11:37 AM on November 18, 2010
So, then, the problem becomes how much energy it takes to create antimatter, right? If it takes thousands of coal firing plants years to make a spaceship's payload worth of fuel, then it's not really worth the time (unless, maybe, it was some Ark-like last ditch solution to climate change, or a deep space impact).
posted by codacorolla at 11:37 AM on November 18, 2010
an amazingly dense fuel
...which is to say, also, the possibility of a briefcase bomb that would require updating maps.
But it's likely to remain too expensive to create and too dangerous to contain for it to be a tempting basis for an energy storage technology anytime soon.
posted by Zed at 11:41 AM on November 18, 2010
...which is to say, also, the possibility of a briefcase bomb that would require updating maps.
But it's likely to remain too expensive to create and too dangerous to contain for it to be a tempting basis for an energy storage technology anytime soon.
posted by Zed at 11:41 AM on November 18, 2010
Big Bang theory predicts that matter and anti-matter should be created in equal amounts at the start of the universe, and basic particle physics predicts that each matter particle would annihilate with an anti-matter particle and there would be nothing left in the Universe.
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 11:43 AM on November 18, 2010 [1 favorite]
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 11:43 AM on November 18, 2010 [1 favorite]
With present technology, anti-matter is tremendously difficult and expensive to make, and tremendously difficult to store once you have made it. This does not necessarily mean that the human race will never discover cheaper and easier ways to make and store anti-matter. No one can really predict the course of future scientific research.
posted by grizzled at 11:45 AM on November 18, 2010
posted by grizzled at 11:45 AM on November 18, 2010
You trap antimatter the same way you trap a unique animal.
Unique up on it.
posted by Astro Zombie at 11:47 AM on November 18, 2010 [2 favorites]
Unique up on it.
posted by Astro Zombie at 11:47 AM on November 18, 2010 [2 favorites]
Matter is basically an indentation in space. Relativity teaches us this. This is not an exact analogy, but a useful way to think of things.
Keep in mind the "stretchy" nature of the fabric of the universe from that clip. The curvature we see there is actually what gravity is, and it's caused by mass. It bends light rays and causes objects to "fall" towards each other. But there are more forces than just gravity. So in addition to its mass, a particle can have a charge. Think of the charge as being transmitted along a stretchy string (this is not "string theory"!). Lay the string down on a flat surface (a table will do). A positively-charged mass is an "upward" facing knot in that string. A negatively-charged mass is a "downward" facing knot. The mass of the particle determines the size of the knot. If you bring two oppositely-charged knots (one up, one down) of the same mass (size) together (say, by pulling on the string), they will cancel each other out and untie. The energy released (the tension on the string; look, it's suddenly longer than it was! If there was a weight on either end, they'd look like they were flying apart (pushed by the release in energy)) is the light (gamma rays!) released as the knots annihilate each other.
This is a very quick and dirty explanation. I welcome any corrections, but I think on a very high level, this is sufficient to kind of explain what's going on. I should probably make a youtube video, though, because I'm not sure if my description was clear.
posted by Eideteker at 11:50 AM on November 18, 2010 [1 favorite]
Keep in mind the "stretchy" nature of the fabric of the universe from that clip. The curvature we see there is actually what gravity is, and it's caused by mass. It bends light rays and causes objects to "fall" towards each other. But there are more forces than just gravity. So in addition to its mass, a particle can have a charge. Think of the charge as being transmitted along a stretchy string (this is not "string theory"!). Lay the string down on a flat surface (a table will do). A positively-charged mass is an "upward" facing knot in that string. A negatively-charged mass is a "downward" facing knot. The mass of the particle determines the size of the knot. If you bring two oppositely-charged knots (one up, one down) of the same mass (size) together (say, by pulling on the string), they will cancel each other out and untie. The energy released (the tension on the string; look, it's suddenly longer than it was! If there was a weight on either end, they'd look like they were flying apart (pushed by the release in energy)) is the light (gamma rays!) released as the knots annihilate each other.
This is a very quick and dirty explanation. I welcome any corrections, but I think on a very high level, this is sufficient to kind of explain what's going on. I should probably make a youtube video, though, because I'm not sure if my description was clear.
posted by Eideteker at 11:50 AM on November 18, 2010 [1 favorite]
So, then, the problem becomes how much energy it takes to create antimatter, right?
Correct. If there were some magic way to transmute matter to antimatter that didn't require a lot of energy input, then it could be very efficient. If we had a way to create antimatter directly from energy at 100% efficiency then it would still be better than any other fuel since it would essentially be a perfect battery. Even at .001% efficiency it'd be 10 times better than nuclear fission still 100,000 times better than chemical rockets.
Which raises a question: is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
posted by jedicus at 11:52 AM on November 18, 2010
Correct. If there were some magic way to transmute matter to antimatter that didn't require a lot of energy input, then it could be very efficient. If we had a way to create antimatter directly from energy at 100% efficiency then it would still be better than any other fuel since it would essentially be a perfect battery. Even at .001% efficiency it'd be 10 times better than nuclear fission still 100,000 times better than chemical rockets.
Which raises a question: is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
posted by jedicus at 11:52 AM on November 18, 2010
Is there any problem where people have been like X is impossible... but not if we could reliably produce antimatter? Obviously there's a difference between capturing and observing a small bit of it, and reliably making a lot of it, but are there any guesses as to practical applications yet?
Nearly perfectly efficient energy storage, since when anti-matter and matter collide, the release an amount of energy equal to the their combined masses times the speed of light squared.
If it takes thousands of coal firing plants years to make a spaceship's payload worth of fuel, then it's not really worth the time (unless, maybe, it was some Ark-like last ditch solution to climate change, or a deep space impact)
Yeah, but weight is the primary problem with lifting off a space ship. If you have enough conventional fuel to take a payload of any practical size (in terms of human space travel) to Mars, it would be too heavy to lift off from earth.
But forget going to mars. With reasonably efficient anti-matter storage, you can start thinking about going a significant percentage of the speed of light, and interstellar travel becomes thinkable.
posted by empath at 11:53 AM on November 18, 2010
Nearly perfectly efficient energy storage, since when anti-matter and matter collide, the release an amount of energy equal to the their combined masses times the speed of light squared.
If it takes thousands of coal firing plants years to make a spaceship's payload worth of fuel, then it's not really worth the time (unless, maybe, it was some Ark-like last ditch solution to climate change, or a deep space impact)
Yeah, but weight is the primary problem with lifting off a space ship. If you have enough conventional fuel to take a payload of any practical size (in terms of human space travel) to Mars, it would be too heavy to lift off from earth.
But forget going to mars. With reasonably efficient anti-matter storage, you can start thinking about going a significant percentage of the speed of light, and interstellar travel becomes thinkable.
posted by empath at 11:53 AM on November 18, 2010
To reply to this question:
Big Bang theory predicts that matter and anti-matter should be created in equal amounts at the start of the universe, and basic particle physics predicts that each matter particle would annihilate with an anti-matter particle and there would be nothing left in the Universe.
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
posted by East Manitoba Regional Junior Kabaddi Champion '94
It would be really hard to explain why the Big Bang would preferrentially emit matter in a different direction than anti-matter, much as if we were to speculate that during the Big Bang, hotter particles were emitted in an opposite direction to the cooler particles. Random processes tend to mix things up, not to divide things by category. So unless there is a specific mechanism that could produce such a result, this would seem to be a weak hypothesis.
posted by grizzled at 11:53 AM on November 18, 2010 [1 favorite]
Big Bang theory predicts that matter and anti-matter should be created in equal amounts at the start of the universe, and basic particle physics predicts that each matter particle would annihilate with an anti-matter particle and there would be nothing left in the Universe.
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
posted by East Manitoba Regional Junior Kabaddi Champion '94
It would be really hard to explain why the Big Bang would preferrentially emit matter in a different direction than anti-matter, much as if we were to speculate that during the Big Bang, hotter particles were emitted in an opposite direction to the cooler particles. Random processes tend to mix things up, not to divide things by category. So unless there is a specific mechanism that could produce such a result, this would seem to be a weak hypothesis.
posted by grizzled at 11:53 AM on November 18, 2010 [1 favorite]
Which raises a question: is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
Maybe a maxwell's demon kind of thing, separating virtual matter/antimatter particle pairs?
posted by empath at 11:54 AM on November 18, 2010
Maybe a maxwell's demon kind of thing, separating virtual matter/antimatter particle pairs?
posted by empath at 11:54 AM on November 18, 2010
So unless there is a specific mechanism that could produce such a result, this would seem to be a weak hypothesis.
The universe is chirally asymmetric, so it's not as if it's unheard of for particular interactions to have a directional preference.
posted by empath at 11:57 AM on November 18, 2010
The universe is chirally asymmetric, so it's not as if it's unheard of for particular interactions to have a directional preference.
posted by empath at 11:57 AM on November 18, 2010
This is also an intriguing question:
is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
posted by jedicus
I don't know of any actual prohibition against doing this, however, current scientific knowledge does not give us even a tiny inkling of how such a thing might be done. If we ever figure it out, this would be a fantastic source of energy. All matter would become high quality fuel. (This was already implicit in the "Back To The Future" movie in which we saw a garbage-powered car.)
posted by grizzled at 11:59 AM on November 18, 2010
is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
posted by jedicus
I don't know of any actual prohibition against doing this, however, current scientific knowledge does not give us even a tiny inkling of how such a thing might be done. If we ever figure it out, this would be a fantastic source of energy. All matter would become high quality fuel. (This was already implicit in the "Back To The Future" movie in which we saw a garbage-powered car.)
posted by grizzled at 11:59 AM on November 18, 2010
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
We'd expect to see a lot more gamma rays from a lot more collisions if there were large quantities of anti-matter out there (or not see anything at all because the universe would be too awash in gamma radiation for life to have had a chance.) So, as far as I understand, we're pretty confident the universe doesn't have much anti-matter. There is some.
posted by Zed at 12:01 PM on November 18, 2010
We'd expect to see a lot more gamma rays from a lot more collisions if there were large quantities of anti-matter out there (or not see anything at all because the universe would be too awash in gamma radiation for life to have had a chance.) So, as far as I understand, we're pretty confident the universe doesn't have much anti-matter. There is some.
posted by Zed at 12:01 PM on November 18, 2010
Yeah, I didn't think we even had a theoretical idea of how it could be done, but if it's not specifically prohibited by known physics it would at least form the basis of a vaguely plausible energy source in science fiction.
posted by jedicus at 12:02 PM on November 18, 2010
posted by jedicus at 12:02 PM on November 18, 2010
So...what does this all mean and what are the possible implications of it all?
The Vatican had better up security quite a bit.
Skeptic: "Not a single Dan Brown joke yet"
Happy now?
posted by Splunge at 12:03 PM on November 18, 2010
The Vatican had better up security quite a bit.
Skeptic: "Not a single Dan Brown joke yet"
Happy now?
posted by Splunge at 12:03 PM on November 18, 2010
We'd expect to see a lot more gamma rays from a lot more collisions if there were large quantities of anti-matter out there (or not see anything at all because the universe would be too awash in gamma radiation for life to have had a chance.) So, as far as I understand, we're pretty confident the universe doesn't have much anti-matter.
Ah, but what if the distribution was so wildly asymmetric that there was very little interaction between antimatter and matter. Something like whole superclusters made of matter and others made of antimatter with virtually nothing in the great voids between them. It's almost certainly not the case, of course, but if it were it would still fit with what we observe about the universe, would it not?
posted by jedicus at 12:06 PM on November 18, 2010
Ah, but what if the distribution was so wildly asymmetric that there was very little interaction between antimatter and matter. Something like whole superclusters made of matter and others made of antimatter with virtually nothing in the great voids between them. It's almost certainly not the case, of course, but if it were it would still fit with what we observe about the universe, would it not?
posted by jedicus at 12:06 PM on November 18, 2010
Which raises a question: is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
I think that even with a perfectly efficient process, there would be some minimum entropic energy cost, but IANAP.
posted by kagredon at 12:07 PM on November 18, 2010
I think that even with a perfectly efficient process, there would be some minimum entropic energy cost, but IANAP.
posted by kagredon at 12:07 PM on November 18, 2010
In related news, IKEA has directions for building a Large Hadron Collider.
posted by A dead Quaker at 12:07 PM on November 18, 2010 [7 favorites]
posted by A dead Quaker at 12:07 PM on November 18, 2010 [7 favorites]
Redditor sends a red crowbar to CERN in case of headcrab emergency
Whew
posted by felix at 12:11 PM on November 18, 2010 [2 favorites]
Whew
posted by felix at 12:11 PM on November 18, 2010 [2 favorites]
I don't understand why there HAS to be anti-matter as well as matter. Is it 1:1? Is the Big Bang supposed to at some point start to collapse in on itself, at which point the matter and anti-matter will wipe each other out and we're left with nothing? And does everything on the table of elements have an anti-particle?
posted by nevercalm at 12:11 PM on November 18, 2010
posted by nevercalm at 12:11 PM on November 18, 2010
Is it possible that they were produced in equal amounts, but were emitted asymmetrically, and we happen to be in a pocket where there is less anti-matter than matter?
Yes! That's something people think about. But it's not likely. If there is a matter region of space and an anti-matter region of space, there must be a boundary between them. There would be constant annihilations happening at the boundary, and that's something we'd expect to be able to observe from earth.
posted by auto-correct at 12:19 PM on November 18, 2010
Yes! That's something people think about. But it's not likely. If there is a matter region of space and an anti-matter region of space, there must be a boundary between them. There would be constant annihilations happening at the boundary, and that's something we'd expect to be able to observe from earth.
posted by auto-correct at 12:19 PM on November 18, 2010
I don't understand why there HAS to be anti-matter as well as matter.
The Big Bang Theory says there has to be.
posted by nomadicink at 12:22 PM on November 18, 2010
The Big Bang Theory says there has to be.
posted by nomadicink at 12:22 PM on November 18, 2010
I don't understand why there HAS to be anti-matter as well as matter.
Symmetry
posted by empath at 12:22 PM on November 18, 2010
Symmetry
posted by empath at 12:22 PM on November 18, 2010
nevercalm, see my comment above as to why it's not 1:1.
The reason there has to be anti-matter is because the equations predict it (lame explanation, I know). Dirac predicted the positron before anyone had observed or thought about anti-matter before. His equations for particle interactions allowed for "negative energy" solutions. Negative energy doesn't really make sense, but those solutions turned out to be anti-matter.
posted by auto-correct at 12:23 PM on November 18, 2010
The reason there has to be anti-matter is because the equations predict it (lame explanation, I know). Dirac predicted the positron before anyone had observed or thought about anti-matter before. His equations for particle interactions allowed for "negative energy" solutions. Negative energy doesn't really make sense, but those solutions turned out to be anti-matter.
posted by auto-correct at 12:23 PM on November 18, 2010
Yes! That's something people think about. But it's not likely. If there is a matter region of space and an anti-matter region of space, there must be a boundary between them. There would be constant annihilations happening at the boundary, and that's something we'd expect to be able to observe from earth.
What if it's very far away? There might be a whole universe of antimatter that's completely outside of our co-moving patch of space time.
posted by empath at 12:24 PM on November 18, 2010
What if it's very far away? There might be a whole universe of antimatter that's completely outside of our co-moving patch of space time.
posted by empath at 12:24 PM on November 18, 2010
What, no photos?
No, but here's a web cam of CERN's LHC, it's pretty interestOH GOD WHAT'S HAP-
posted by sephira at 12:27 PM on November 18, 2010 [4 favorites]
No, but here's a web cam of CERN's LHC, it's pretty interestOH GOD WHAT'S HAP-
posted by sephira at 12:27 PM on November 18, 2010 [4 favorites]
Which raises a question: is there a prohibition against an (essentially) energy-free transmutation of matter to antimatter? Is that too close to getting something for nothing?
The CP violation that we know about occurs in K and B meson system, in which a meson spontaneously transforms into an anti-meson. Check out this wiki link on K mesons. The BABAR experiment at Stanford (among others) does this with B mesons. This doesn't get you any free energy, though.
posted by auto-correct at 12:29 PM on November 18, 2010 [1 favorite]
The CP violation that we know about occurs in K and B meson system, in which a meson spontaneously transforms into an anti-meson. Check out this wiki link on K mesons. The BABAR experiment at Stanford (among others) does this with B mesons. This doesn't get you any free energy, though.
posted by auto-correct at 12:29 PM on November 18, 2010 [1 favorite]
What if it's very far away? There might be a whole universe of antimatter that's completely outside of our co-moving patch of space time.
Sure. I'm not an astronomer, so I only hear about this things second hand. I do know that it's something people are actively doing experiments on. I'm pretty sure the general opinion of the community is "we're pretty sure anti-matter galaxies don't exist, but they're still worth looking for".
Checking whether the spectrum of anti-Hydrogen is the same as Hydrogen will help these searches along.
posted by auto-correct at 12:33 PM on November 18, 2010
Sure. I'm not an astronomer, so I only hear about this things second hand. I do know that it's something people are actively doing experiments on. I'm pretty sure the general opinion of the community is "we're pretty sure anti-matter galaxies don't exist, but they're still worth looking for".
Checking whether the spectrum of anti-Hydrogen is the same as Hydrogen will help these searches along.
posted by auto-correct at 12:33 PM on November 18, 2010
You know, someone who actually knows what they are talking about should do a round up post on the Standard Model explaining all this stuff. That would be fancy.
posted by empath at 12:36 PM on November 18, 2010
posted by empath at 12:36 PM on November 18, 2010
Also, I'm pretty sure Big Bang theory predicts that there was causal contact between all points of the early Universe. I think this was shown via the Cosmic Microwave Background (someone please correct me if I'm wrong). So the anti-matter would have annihilated before it could get causally separated from the matter part of the Universe.
posted by auto-correct at 12:39 PM on November 18, 2010
posted by auto-correct at 12:39 PM on November 18, 2010
"The light is green, the trap is clean, the antihydrogen is incarcerated here in our custom made storage facility."posted by ...possums at 12:41 PM on November 18, 2010 [2 favorites]
Mind+This=Blown
I love this stuff, where you read it once, scratch your head and say "whaaaaaa? That can't be real." And then someone shows you a way it might be real, and how they arrived at that conclusion, and your understanding of the world and reality gets a little closer to being like some crazy movie or video game. I'll clearly have to go through this thread again, but man, is it interesting.
You know, someone who actually knows what they are talking about should do a round up post on the Standard Model explaining all this stuff. That would be fancy.
Yes please. And clearly I need to go find my copy of "Dancing Wu-Li Masters" and pick up where I left off, which was on like page 9.
posted by nevercalm at 12:41 PM on November 18, 2010
I love this stuff, where you read it once, scratch your head and say "whaaaaaa? That can't be real." And then someone shows you a way it might be real, and how they arrived at that conclusion, and your understanding of the world and reality gets a little closer to being like some crazy movie or video game. I'll clearly have to go through this thread again, but man, is it interesting.
You know, someone who actually knows what they are talking about should do a round up post on the Standard Model explaining all this stuff. That would be fancy.
Yes please. And clearly I need to go find my copy of "Dancing Wu-Li Masters" and pick up where I left off, which was on like page 9.
posted by nevercalm at 12:41 PM on November 18, 2010
Another question that I will answer:
And does everything on the table of elements have an anti-particle?
posted by nevercalm
The periodic table of elements contains elements, not particles. Elements are made up of particles but they are not themselves particles, they are composite entities. Even the very simplest isotope (or form) of the simplest element, hydrogen one, consists of two particles, a proton and an electron.
And as I said in a previous answer, all particles have anti-particles, although photons are considered to be their own anti-particles. When we say that a particle has an anti-particle, by the way, this does not necessarily mean that you will enocunter this anti-particle in nature. It means that it is possible for the anti-particle to exist, and with the right kind of collision with a sufficiently powerful particle accelerator, it is possible to create that particle. Some particles are quite rare.
posted by grizzled at 12:45 PM on November 18, 2010
And does everything on the table of elements have an anti-particle?
posted by nevercalm
The periodic table of elements contains elements, not particles. Elements are made up of particles but they are not themselves particles, they are composite entities. Even the very simplest isotope (or form) of the simplest element, hydrogen one, consists of two particles, a proton and an electron.
And as I said in a previous answer, all particles have anti-particles, although photons are considered to be their own anti-particles. When we say that a particle has an anti-particle, by the way, this does not necessarily mean that you will enocunter this anti-particle in nature. It means that it is possible for the anti-particle to exist, and with the right kind of collision with a sufficiently powerful particle accelerator, it is possible to create that particle. Some particles are quite rare.
posted by grizzled at 12:45 PM on November 18, 2010
God, my head is spinning trying to make sense of this. I'm just going to sit here and smile and nod. I really wish I was intelligent enough to understand the science of it.
posted by Solomon at 12:45 PM on November 18, 2010
posted by Solomon at 12:45 PM on November 18, 2010
So the anti-matter would have annihilated before it could get causally separated from the matter part of the Universe.
Then that would mean that there wasn't 1:1 matter-antimatter, otherwise no matter would be left over, only a whole lotta energy. At some point, all the antimatter was used up but there was still some matter left, unless somehow everything was turned into photons and then somehow condensed back down into matter again, but not as anti-matter.
posted by AzraelBrown at 12:47 PM on November 18, 2010
Then that would mean that there wasn't 1:1 matter-antimatter, otherwise no matter would be left over, only a whole lotta energy. At some point, all the antimatter was used up but there was still some matter left, unless somehow everything was turned into photons and then somehow condensed back down into matter again, but not as anti-matter.
posted by AzraelBrown at 12:47 PM on November 18, 2010
I think it's easier to understand this stuff when you ignore the fact that it's real and just focus on the math. Particles are just a bunch of vectors on a 4 dimensional grid. Everything else is metaphor.
posted by empath at 12:48 PM on November 18, 2010 [2 favorites]
posted by empath at 12:48 PM on November 18, 2010 [2 favorites]
Then that would mean that there wasn't 1:1 matter-antimatter, otherwise no matter would be left over, only a whole lotta energy. At some point, all the antimatter was used up but there was still some matter left, unless somehow everything was turned into photons and then somehow condensed back down into matter again, but not as anti-matter.
Exactly. And that comes back to the problem of CP-violation that I mentioned up thread. The standard picture of the Big Bang right now is that matter and anti-matter were produced in a 1:1 ratio, and as they annihilated there were enough CP-violating processes involved that there was matter leftover but not anti-matter. We understand some CP violation, but not enough to totally explain the situation.
posted by auto-correct at 12:53 PM on November 18, 2010
Exactly. And that comes back to the problem of CP-violation that I mentioned up thread. The standard picture of the Big Bang right now is that matter and anti-matter were produced in a 1:1 ratio, and as they annihilated there were enough CP-violating processes involved that there was matter leftover but not anti-matter. We understand some CP violation, but not enough to totally explain the situation.
posted by auto-correct at 12:53 PM on November 18, 2010
By "(essentially) energy-free" I meant "cheap relative to the fantastic amount of energy you can get out of annihilating matter with antimatter" not zero energy cost in an absolute sense.
posted by jedicus at 1:16 PM on November 18, 2010
posted by jedicus at 1:16 PM on November 18, 2010
Antimatter atoms produced and trapped at CERN
But can we make them talk?
posted by fartknocker at 1:47 PM on November 18, 2010
But can we make them talk?
posted by fartknocker at 1:47 PM on November 18, 2010
o I've got a proverbial bucket of salt here just in case: but if there wasn't some sort of universal law against energy-free transmutation slash something for nothing wouldn't everything just transmute?
There is the law of conservation of energy, but conversion of matter to energy and vice versa is totally fine.
However, I don't think there is anyway to convert matter to anti-matter without the intermediate step of converting matter to energy first, which takes some doing.
posted by empath at 1:51 PM on November 18, 2010
There is the law of conservation of energy, but conversion of matter to energy and vice versa is totally fine.
However, I don't think there is anyway to convert matter to anti-matter without the intermediate step of converting matter to energy first, which takes some doing.
posted by empath at 1:51 PM on November 18, 2010
Anti-matter is like matter, only the opposite. Also, if they touch each other there's a ginormous explosion.
It's like mixing pesto and antipasto.
posted by kirkaracha at 2:04 PM on November 18, 2010 [2 favorites]
Dear AskMe: As per the instructions, I filled my brand new universe with a full load of energy and waited for a bit for matter and anti-matter to condense from the super-heated energy. But when I came back after getting the mail, the whole thing was filled with matter. Where's my anti-matter?
And, yes, I checked under the sofa cushions. This is such a ripoff. I mean, how are you supposed to build jetpacks and starships with only matter? And to make things worse, there are now things made completely of matter crawling all over, thinking they own the place. Should I have stuck with knitting?
posted by Cironian at 2:31 PM on November 18, 2010 [6 favorites]
And, yes, I checked under the sofa cushions. This is such a ripoff. I mean, how are you supposed to build jetpacks and starships with only matter? And to make things worse, there are now things made completely of matter crawling all over, thinking they own the place. Should I have stuck with knitting?
posted by Cironian at 2:31 PM on November 18, 2010 [6 favorites]
CERN has a site devoted to antimatter that appears to be aimed towards classroom teaching. It includes archives of webcast lectures and video clips.
posted by zarq at 2:33 PM on November 18, 2010 [4 favorites]
posted by zarq at 2:33 PM on November 18, 2010 [4 favorites]
There's kind of a problem with all conservation laws.
As Feynman points out in The Character of Physical Law, all conservation laws must be strictly local because of relativity. If charge is always conserved, for example, meaning that at every moment in time the net amount of charge in the universe is always the same, this condition can never be met by a process in which an apparent violation of conservation of charge is balanced by a simultaneous violation in the opposite direction which takes place some distance away.
This is due to the fact that all inertial reference frames are equally valid and only inertial reference frames that are at rest with respect to each other can agree on the simultaneity of two events which are separate from each other in space; therefore conservation laws must operate at points in space.
The problem arises because the Heisenberg uncertainty principle says that the product of the uncertainty in the momentum of anything times the uncertainty in the position of that thing can never be lower than a certain fixed number.
Therefore, it makes no sense to claim that our process which conserves charge (the creation of an electron and a positron from a gamma ray, say) happens at a point. It must always happen instead in a region of space delimited by the uncertainty about the momentum of that process.
Does that mean all conservation laws are only approximate and admit greater or lesser random violations, random violations which could in principle-- factoring in the unique parameters surrounding the big bang-- account for matter/antimatter asymmetry?
posted by jamjam at 2:41 PM on November 18, 2010
As Feynman points out in The Character of Physical Law, all conservation laws must be strictly local because of relativity. If charge is always conserved, for example, meaning that at every moment in time the net amount of charge in the universe is always the same, this condition can never be met by a process in which an apparent violation of conservation of charge is balanced by a simultaneous violation in the opposite direction which takes place some distance away.
This is due to the fact that all inertial reference frames are equally valid and only inertial reference frames that are at rest with respect to each other can agree on the simultaneity of two events which are separate from each other in space; therefore conservation laws must operate at points in space.
The problem arises because the Heisenberg uncertainty principle says that the product of the uncertainty in the momentum of anything times the uncertainty in the position of that thing can never be lower than a certain fixed number.
Therefore, it makes no sense to claim that our process which conserves charge (the creation of an electron and a positron from a gamma ray, say) happens at a point. It must always happen instead in a region of space delimited by the uncertainty about the momentum of that process.
Does that mean all conservation laws are only approximate and admit greater or lesser random violations, random violations which could in principle-- factoring in the unique parameters surrounding the big bang-- account for matter/antimatter asymmetry?
posted by jamjam at 2:41 PM on November 18, 2010
don't shake hands with a time traveller
Shake hands? Shake hands? That bastard first acted all buddy-buddy, claiming to be my grandson, then out of nowhere he pulled out a laser gun and tried to shoot me!
Never trust a time traveller.
posted by ymgve at 3:42 PM on November 18, 2010
Shake hands? Shake hands? That bastard first acted all buddy-buddy, claiming to be my grandson, then out of nowhere he pulled out a laser gun and tried to shoot me!
Never trust a time traveller.
posted by ymgve at 3:42 PM on November 18, 2010
> It is possible for these particles to have these charges reversed, but we never see this in nature. That kind of matter is called antimatter.
This explains why we've never seen the Anti-Christ.
posted by mmrtnt at 4:54 PM on November 18, 2010
This explains why we've never seen the Anti-Christ.
posted by mmrtnt at 4:54 PM on November 18, 2010
You've got to accentuate the negative
Eliminate the positive
And latch on to the indefinite
Don't mess with Mr. In-Between
posted by bwg at 5:02 PM on November 18, 2010 [1 favorite]
Eliminate the positive
And latch on to the indefinite
Don't mess with Mr. In-Between
posted by bwg at 5:02 PM on November 18, 2010 [1 favorite]
It's like mixing pesto and antipasto.
Or Maddie and Auntie Maddie.
They hate each other
posted by mmrtnt at 5:08 PM on November 18, 2010
Or Maddie and Auntie Maddie.
They hate each other
posted by mmrtnt at 5:08 PM on November 18, 2010
"I feel safe in predicting that at some point in the future this knowledge will be used in new and creative ways to kill poor people with powerful weapons."
But first, it will be used for porn and advertising.
posted by gingerest at 5:51 PM on November 18, 2010 [2 favorites]
But first, it will be used for porn and advertising.
posted by gingerest at 5:51 PM on November 18, 2010 [2 favorites]
How do we know we're not already made of anti-matter, and what we've just created is plain old matter?
posted by Evilspork at 6:53 PM on November 18, 2010
posted by Evilspork at 6:53 PM on November 18, 2010
Discovering the anti-particles was (relatively) easy: they get produced all the time (especially in particle colliders), they just don't last very long because once they interact with their normal-matter equivalent, they annihilate into a photon.
Right.
Fermilab has been making antimatter for a couple of decades now. Right now...of course, the goddamn notify server is down. Hmm. fnal.gov as a whole seems to be broken.
Anyway. Fermilab has been making antimatter for a long time, because the Tevatron collides protons and antiprotons. Fermilab has also made a fair number of positrons, combine the two, and you have antihydrogen.
But since Fermilab is a coillider labratory, with a collider that doesn't blow up, they tend to ram thier pbars into proton and get Things.
Things like the top quark, the Ξ baryon, and the Ω-b baryon -- a double strange baryon, that is, it's two strange quarks and a bottom quark. Yes, I just wrote that on MetaFilter. I so rule.
posted by eriko at 8:02 PM on November 18, 2010 [1 favorite]
Right.
Fermilab has been making antimatter for a couple of decades now. Right now...of course, the goddamn notify server is down. Hmm. fnal.gov as a whole seems to be broken.
Anyway. Fermilab has been making antimatter for a long time, because the Tevatron collides protons and antiprotons. Fermilab has also made a fair number of positrons, combine the two, and you have antihydrogen.
But since Fermilab is a coillider labratory, with a collider that doesn't blow up, they tend to ram thier pbars into proton and get Things.
Things like the top quark, the Ξ baryon, and the Ω-b baryon -- a double strange baryon, that is, it's two strange quarks and a bottom quark. Yes, I just wrote that on MetaFilter. I so rule.
posted by eriko at 8:02 PM on November 18, 2010 [1 favorite]
How do we know we're not already made of anti-matter, and what we've just created is plain old matter?
It doesnt really make a differenec, but you wouldn't call the first one you name "anti-matter"
posted by empath at 9:25 PM on November 18, 2010
It doesnt really make a differenec, but you wouldn't call the first one you name "anti-matter"
posted by empath at 9:25 PM on November 18, 2010
The post is phrased like this is the first time there has ever been antimatter to study, and that is just not true.
posted by tehloki at 1:00 AM on November 19, 2010
posted by tehloki at 1:00 AM on November 19, 2010
Every type of elementary particle has an anti-matter equivalent: ... quarks have anti-quarks
Shouldn't they be called InDesigns?
posted by Grangousier at 1:42 AM on November 19, 2010
Shouldn't they be called InDesigns?
posted by Grangousier at 1:42 AM on November 19, 2010
The post is phrased like this is the first time there has ever been antimatter to study, and that is just not true.
It's phrased like this is the first time there's been anti-matter atoms captured long enough to study, which is exactly the case. As has been discussed much above, anti-matter particles have been seen in cosmic rays and laboratories for well over 50 years. There's a difference.
Fermilab has been making antimatter for a couple of decades now.
This is true, but colliders started making anti-matter long before the Tevatron started up. Tevatron's great-great-uncle, the Bevatron see what they did there was the first to make anti-protons. Making positrons is actually even easier and doesn't take much effort; they can be observed in everything from cosmic rays (where they were discovered in the early 1930s) to ambient radiation from the concrete in your home.
Also, even though the LHC is a proton-proton collider (no anti-matter input), the collisions still lead to lots of anti-matter!
posted by auto-correct at 1:48 AM on November 19, 2010 [1 favorite]
It's phrased like this is the first time there's been anti-matter atoms captured long enough to study, which is exactly the case. As has been discussed much above, anti-matter particles have been seen in cosmic rays and laboratories for well over 50 years. There's a difference.
Fermilab has been making antimatter for a couple of decades now.
This is true, but colliders started making anti-matter long before the Tevatron started up. Tevatron's great-great-uncle, the Bevatron see what they did there was the first to make anti-protons. Making positrons is actually even easier and doesn't take much effort; they can be observed in everything from cosmic rays (where they were discovered in the early 1930s) to ambient radiation from the concrete in your home.
Also, even though the LHC is a proton-proton collider (no anti-matter input), the collisions still lead to lots of anti-matter!
posted by auto-correct at 1:48 AM on November 19, 2010 [1 favorite]
For the people asking for what the practical applications of capturing, studying, and eventually storing antimatter might be. This advancement seems to be the first step towards making it possible to colonize the solar system.
Positron Propelled and Powered Space Transport Vehicle for Planetary Missions
Why Positrons?
Antimatter has highest specific energy in existence.
No residual radiation.
Large amounts can be made available.
Promising storage developments.
We estimate approximately 4 mg of positrons for a one-way trip to Mars with a system mass of 100,000 kg (e+ not used for powering payload).
Conclusions
Positron-based engines are “thick”.
“Thick” means gamma rays travel further to interact with propellant.
Solid-Core engine will work.
More detailed studies required.
Gas-core concept
High density gas must be kept close to high-energy gamma rays.
Means of reducing energies of photons to allow low-Z, high Isppropellant should be
investigated.
Ablative Sänger engine promising based on previous work at Penn State.
Antimatter rocket
The chief practical difficulties with antimatter rockets are the problems of creating antimatter and storing it. Creating antimatter requires input of vast amounts of energy, at least equivalent to the rest energy of the created particle/antiparticle pairs, and typically (for antiproton production) tens of thousands to millions of times more. Most proposed antimatter rocket designs require a large amount of antimatter (around 10 grams to reach Mars in one month). Most storage schemes proposed for interstellar craft require the production of frozen pellets of antihydrogen. This requires cooling of antiprotons, binding to positrons, and capture of the resulting antihydrogen atoms - tasks which have, as of 2010, been performed only for small numbers of individual atoms. Storage of antimatter is typically done by trapping electrically charged frozen antihydrogen pellets in Penning or Paul traps. While there is no theoretical barrier to these tasks being performed on the scale required to fuel an antimatter rocket, they are expected to be extremely (and perhaps prohibitively) expensive.
A secondary problem is the extraction of useful energy or momentum from the products of antimatter annihilation, which are primarily in the form of extremely energetic ionizing radiation. The antimatter mechanisms proposed to date have for the most part provided plausible mechanisms for harnessing energy from these annihilation products.
posted by AElfwine Evenstar at 7:40 AM on November 19, 2010
Positron Propelled and Powered Space Transport Vehicle for Planetary Missions
Why Positrons?
Antimatter has highest specific energy in existence.
No residual radiation.
Large amounts can be made available.
Promising storage developments.
We estimate approximately 4 mg of positrons for a one-way trip to Mars with a system mass of 100,000 kg (e+ not used for powering payload).
Conclusions
Positron-based engines are “thick”.
“Thick” means gamma rays travel further to interact with propellant.
Solid-Core engine will work.
More detailed studies required.
Gas-core concept
High density gas must be kept close to high-energy gamma rays.
Means of reducing energies of photons to allow low-Z, high Isppropellant should be
investigated.
Ablative Sänger engine promising based on previous work at Penn State.
Antimatter rocket
The chief practical difficulties with antimatter rockets are the problems of creating antimatter and storing it. Creating antimatter requires input of vast amounts of energy, at least equivalent to the rest energy of the created particle/antiparticle pairs, and typically (for antiproton production) tens of thousands to millions of times more. Most proposed antimatter rocket designs require a large amount of antimatter (around 10 grams to reach Mars in one month). Most storage schemes proposed for interstellar craft require the production of frozen pellets of antihydrogen. This requires cooling of antiprotons, binding to positrons, and capture of the resulting antihydrogen atoms - tasks which have, as of 2010, been performed only for small numbers of individual atoms. Storage of antimatter is typically done by trapping electrically charged frozen antihydrogen pellets in Penning or Paul traps. While there is no theoretical barrier to these tasks being performed on the scale required to fuel an antimatter rocket, they are expected to be extremely (and perhaps prohibitively) expensive.
A secondary problem is the extraction of useful energy or momentum from the products of antimatter annihilation, which are primarily in the form of extremely energetic ionizing radiation. The antimatter mechanisms proposed to date have for the most part provided plausible mechanisms for harnessing energy from these annihilation products.
posted by AElfwine Evenstar at 7:40 AM on November 19, 2010
At the end, it will be revealed that we were the antimatter all along...
posted by MysticMCJ at 10:31 AM on November 19, 2010
posted by MysticMCJ at 10:31 AM on November 19, 2010
Hairy Lobster wrote: "bacon"Eww, I don't want my bacon to have a goatee.
posted by secretseasons at 11:39 AM on November 19, 2010
My understanding of physics pretty much ends at the high school level so I apologize if this question is a little basic. I saw this data (pulled from Wikipedia) quoted on the gizmodo article about this:
The reaction of 1 kilogram of antimatter with 1 kilogram of matter would produce 180 petajoules of energy or the rough equivalent of 43 megatons of TNT. For comparison, Tsar Bomba, the largest nuclear weapon ever detonated, reacted an estimated yield of 50 megatons, which required the use of hundreds of kilograms of fissile material.
My understanding is that in either of these cases mass is getting converted into energy and the amount is calculated as E=MC^2. This still holds true for the matter/anti-matter reaction right? The difference being that, in the nuclear weapon detonation, most of the fuel doesn't get converted to energy while the matter/anti-matter reaction converts 100% of the mass of the inputs into energy. Is that right?
posted by VTX at 7:22 PM on November 19, 2010
The reaction of 1 kilogram of antimatter with 1 kilogram of matter would produce 180 petajoules of energy or the rough equivalent of 43 megatons of TNT. For comparison, Tsar Bomba, the largest nuclear weapon ever detonated, reacted an estimated yield of 50 megatons, which required the use of hundreds of kilograms of fissile material.
My understanding is that in either of these cases mass is getting converted into energy and the amount is calculated as E=MC^2. This still holds true for the matter/anti-matter reaction right? The difference being that, in the nuclear weapon detonation, most of the fuel doesn't get converted to energy while the matter/anti-matter reaction converts 100% of the mass of the inputs into energy. Is that right?
posted by VTX at 7:22 PM on November 19, 2010
VTX, when fission reactions happen, an element decays into a smaller element (or two). Usually, the number of particles is almost exactly the same, but the smaller element takes less energy to hold together. This energy differential, while much greater than a chemical reaction like combustion at the same scale, is very tiny (which is why it would have taken 50,000,000 tons of TNT to equal Tsar Bomba). Fusion reactions function on the opposite principle. Certain smaller elements prefer to be larger (and everything in the universe is turning to iron (56Fe); anything smaller wants to get bigger and anything bigger wants to get smaller. Iron has the lowest possible bonding energy; it has just enough protons and neutrons for everything to lock together just right and as tightly as possible).
But in either of these cases, you are talking about a reorganization of the existing particles. You may shed an electron (ß decay) or even a whole helium nucleus (2 protons and 2 neutrons, α decay). You're not actually destroying these particles, just giving them a shove (some mass is shed in the form of energy, but much muuuuch less than a whole particle). With matter-antimatter annihilation, you are actually converting an entire particle's mass directly to energy.
So while a fusion reaction of Deuterium (an isotope of hydrogen; one proton and one neutron) + Tritium (still hydrogen; one proton and TWO neutrons!) → He (2 protons and 2 neutrons) + a spare neutron (same number of particles, count them!) yields 17.6 MeV, the annhilation of a single neutron-antineutron pair at rest yields 3,600 MeV. The total mass of the fusion reaction is 5u (protons and neutrons have almost the same mass, an atomic mass unit "u"). The total mass of the annihilation is only 2u. That means 2/5 of the mass has produced over 200 times the energy; that's over 500 times more efficient!
posted by Eideteker at 11:47 PM on November 19, 2010
But in either of these cases, you are talking about a reorganization of the existing particles. You may shed an electron (ß decay) or even a whole helium nucleus (2 protons and 2 neutrons, α decay). You're not actually destroying these particles, just giving them a shove (some mass is shed in the form of energy, but much muuuuch less than a whole particle). With matter-antimatter annihilation, you are actually converting an entire particle's mass directly to energy.
So while a fusion reaction of Deuterium (an isotope of hydrogen; one proton and one neutron) + Tritium (still hydrogen; one proton and TWO neutrons!) → He (2 protons and 2 neutrons) + a spare neutron (same number of particles, count them!) yields 17.6 MeV, the annhilation of a single neutron-antineutron pair at rest yields 3,600 MeV. The total mass of the fusion reaction is 5u (protons and neutrons have almost the same mass, an atomic mass unit "u"). The total mass of the annihilation is only 2u. That means 2/5 of the mass has produced over 200 times the energy; that's over 500 times more efficient!
posted by Eideteker at 11:47 PM on November 19, 2010
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posted by joe lisboa at 9:53 AM on November 18, 2010 [8 favorites]