antimatter

[frankm134]

ok I have theorized a way to contain antimatter

say you have a cylindrical container that you want to store antimatter with.

so you would want to have it positively charge (you want it positively charged because antimatter has positrons. the opposite of electrons)

then make antimatter(its a long process to make so I won't explain it) and add 1 more positron so it's positively charged so electromagnetic forces of like charges repelling stops the matter container from destroying the antimatter you made.

[K^2]

Nope. Doesn't work. There is a theorem in classical electrodynamics that says that you cannot trap a charge with electrostatic forces in free space.

Edit: Just to add a bit of detail. The key here is that you cannot have a maximum/minimum in electrostatic potential that is not located on a source.

[Boomerang]

You hypothesized that. And as K^2 said, it wouldn't work.

[Bill Phil]

Well, antimatter is way beyond our technology. We've only made a few particles of the stuff. The best way to contain it is to put it in an electromagnetic trap, but the trap needs to be extremely uniform or very very very big relative to the amount you're storing.

Antimatter is actually kind of useless, except as a catalyst for other more useful reactions. That's what ICAN-II does. And it doesn't even need that much antimatter(less than a gram). Either way it's beyond us currently. So let's wait till we know more about antimatter, which means imperial observations. Which requires a large amount of antimatter to do.

Although, Earth and Saturn have a good amount of antimatter trapped in their magnetic fields...

And it's replenished...

[K^2]

Antimatter is the only stuff that gives you I_SP of c/g. Hopefully, we'll find a workaround for that, but otherwise, might be the only way to go for interstellar.

[KSK]

Well, antimatter is way beyond our technology. We've only made a few particles of the stuff. The best way to contain it is to put it in an electromagnetic trap, but the trap needs to be extremely uniform or very very very big relative to the amount you're storing.

Antimatter is actually kind of useless, except as a catalyst for other more useful reactions. That's what ICAN-II does. And it doesn't even need that much antimatter(less than a gram). Either way it's beyond us currently. So let's wait till we know more about antimatter, which means imperial observations. Which requires a large amount of antimatter to do.

Although, Earth and Saturn have a good amount of antimatter trapped in their magnetic fields...

And it's replenished...

Empirical observations? Unless CERN has been annexed by the Swiss Empire.

I would argue that we know plenty about antimatter - we've been making and using it in particle physics labs for decades, and we're getting to the point where we can look at anti-atoms in detail, rather than being limited to charged particles. So I disagree that we need large amounts of it for empirical observations.

Practical applications in energy generation or spacecraft propulsion though? Yeah, that's way beyond us at the moment.

[Bill Phil]

Empirical observations? Unless CERN has been annexed by the Swiss Empire.

I would argue that we know plenty about antimatter - we've been making and using it in particle physics labs for decades, and we're getting to the point where we can look at anti-atoms in detail, rather than being limited to charged particles. So I disagree that we need large amounts of it for empirical observations.

Practical applications in energy generation or spacecraft propulsion though? Yeah, that's way beyond us at the moment.

Well, it could have strange qualities that won't be apparent until it has a certain size. It could, keep in mind could have a different reaction to gravity, less of a reaction or even repelling it. But probably not. I'm saying that the best observations are empirical ones. Besides, we'll need that much antimatter before we ever build a decently sized ship to go interstellar. It's best to know what it's qualities are.

[K^2]

Theory predicts identical bulk behavior of matter and antimatter, including with respect to gravity. Granted, there is very little, almost none, direct experimental data, but there are a whole bunch of indirect results that would have been different if there was a reason for bulk properties to be different.

So while it might be nice, at some point, to confirm all of this with actual measurements, we can pretty much carry on with assumption that matter and antimatter behave the same way.

[Mazon Del]

At least we are getting much better with the AM traps. The last one held onto some for something like 11 minutes? I forget, but it was a ridiculous increase over the last one which was like 20-30 seconds.

Right now as others have said, antimatter is only useful right now to let you do other experiments, or as a "perfect battery". You cannot use currently generated AM to power something like a city, because you had to spend the same amount of energy just to produce it. Now if we did rig up some crazy high altitude/orbital collector from the poles, that would be different.

[KSK]

Well, it could have strange qualities that won't be apparent until it has a certain size. It could, keep in mind could have a different reaction to gravity, less of a reaction or even repelling it. But probably not. I'm saying that the best observations are empirical ones. Besides, we'll need that much antimatter before we ever build a decently sized ship to go interstellar. It's best to know what it's qualities are.

We're working on it, although admittedly, the results aren't particularly conclusive yet!

[TheDarkStar]

Nope. Doesn't work. There is a theorem in classical electrodynamics that says that you cannot trap a charge with electrostatic forces in free space.

Edit: Just to add a bit of detail. The key here is that you cannot have a maximum/minimum in electrostatic potential that is not located on a source.

This is correct only with constant forces, though. As soon as you get reactive mechanisms, you can hold things in free space - it's how MagLev works. It just takes a constant input of energy.

[-Velocity-]

Nope. Doesn't work. There is a theorem in classical electrodynamics that says that you cannot trap a charge with electrostatic forces in free space.

Edit: Just to add a bit of detail. The key here is that you cannot have a maximum/minimum in electrostatic potential that is not located on a source.

Not exactly sure what you're referring to, but according to Gauss's law, the field inside, for example, a charged spherical shell would be zero, since there is no charge enclosed.

That said, I don't see why you could you not have an active system that distributed charges around to keep a piece of antimatter electrostatically confined. You can give a piece of antimatter a certain charge- say, shoot it with a positron or electron beam (might be easier to annihilate a few positrons in the antimatter using electrons), and then when the antimatter approached one side of the container, apply an electric field to repel it.

Or, maybe spin it up in a centrifuge (or just place it in a gravity field) between two cup-shaped electrodes, and charge it up (and recharge, when/if necessary) with an electron beam. Apply a voltage between the two electrodes to create an electric field. It would be attracted to the top electrode, and repelled by the bottom electrode. If it got too close to the top electrode, it would start to pull in, but if you were fast enough, you could detect the pull in and dump the voltage before the antimatter came into contact with the top electrode. And remember, the electrodes are cup-shaped, so gravity/centrifugal force naturally holds the antimatter in the lowest point of the cup.

Edited November 11, 2014 by |Velocity|

[Soda Popinski]

For anyone interested, here's the paper on trapping antihydrogen for 1000 seconds. Can someone smarter than me explain how they can hold a neutral atom in an electromagnetic bottle (Penning trap)? I'll try to figure it out myself later.

http://arxiv.org/ftp/arxiv/papers/1104/1104.4982.pdf

[-Velocity-]

For anyone interested, here's the paper on trapping antihydrogen for 1000 seconds. Can someone smarter than me explain how they can hold a neutral atom in an electromagnetic bottle (Penning trap)? I'll try to figure it out myself later.

http://arxiv.org/ftp/arxiv/papers/1104/1104.4982.pdf

I think it's diamagnetism.

http://en.wikipedia.org/wiki/Diamagnetism

[problemecium]

^ I second this, and also even a neutral atom has a negative charge on its surface (due to the electrons). In practice this is the main reason solid objects can't pass through each other and we don't fall through the ground into Earth's core - as the atoms grow very close together, the electrons elbow each other out of their personal spaces with their negative charge (of course the technical explanation is more, well, technical, but this is the gist of it).

[K^2]

TNot exactly sure what you're referring to, but according to Gauss's law, the field inside, for example, a charged spherical shell would be zero, since there is no charge enclosed.

Or you can charge it non-uniformly, and have some variable potential inside. But that potential still cannot have a maximum or minimum in empty space. So you cannot suspend something in the middle with any fixed arrangement of charges.

That said, I don't see why you could you not have an active system that distributed charges around to keep a piece of antimatter electrostatically confined.

Active system is the key word here. OP suggested keeping it in place by mere fact of charging the container.

[GregA]

Or you can charge it non-uniformly, and have some variable potential inside. But that potential still cannot have a maximum or minimum in empty space. So you cannot suspend something in the middle with any fixed arrangement of charges.

Active system is the key word here. OP suggested keeping it in place by mere fact of charging the container.

Hey K Squared.

What would happen if you cooled the anti-hydrogen enough that it became a superconductor, then held it aloft with the Meissner effect?

[K^2]

Anything you'd like, in the bizarre universe where hydrogen turns superconductive at low temperatures.

The conditions under which hydrogen is expected to be metallic and is predicted by some analysis to be superconductive are yet to be produced in the lab.

Although, I'm sure it won't stop you from claiming that MSMH is the main component of dark matter.

[Wanderfound]

Well, antimatter is way beyond our technology. We've only made a few particles of the stuff.

Ahh...no. Antimatter is routinely used in common medical technology. A PET scan (Positron Emission Tomography) is an antimatter device; positrons are antimatter electrons.

Antimatter isn't magic, any more than normal matter is.

[Bill Phil]

Ahh...no. Antimatter is routinely used in common medical technology. A PET scan (Positron Emission Tomography) is an antimatter device; positrons are antimatter electrons.

Antimatter isn't magic, any more than normal matter is.

Any good source?

I'm not saying magic, it's just a very volatile substance that we can't make much of.

Plus, PETs only TRACK positrons. They don't shoot a super-beam or anything resembling a beam of particles.

[Wanderfound]

Any good source?

I'm not saying magic, it's just a very volatile substance that we can't make much of.

Plus, PETs only TRACK positrons. They don't shoot a super-beam or anything resembling a beam of particles.

I used to work with PET scanners professionally; ex-neuroscientist. If you're looking for a citation, you're probably best off starting with Wiki (http://en.wikipedia.org/wiki/Positron_emission_tomography) and then drilling down into the references at the bottom of the article.

The basic way that a PET scan works is that you inject the patient with a mildly radioactive substance that is chemically attracted to the biological structure that you're interested in tracking (for example, FDG-PET brainscans use a form of radioactive glucose that is enthusiastically absorbed by active neurons). As the radiation decays, it produces positrons, which in turn produce bursts of gamma radiation when they collide with normal matter. The scanner can identify the source location of the gamma, which allows the measurement of where in the body the positron annihilation is occurring.

Making antimatter is easy; all you need is some radioactive decay. Pretty much every radiologically active thing is constantly surrounded by a transient cloud of the stuff. The hard part is in preventing it from immediately contacting normal matter and mutually annihilating.

[K^2]

To be precise, the scanner looks for coincidence events, because an electron-positron annihilation event usually produces a pair of photons with almost exactly the opposite momenta. Detecting both of them gives you a line on which event took place, which is very useful for 3D reconstruction.

And while nobody's using antimatter beams in medicine yet, there are people working on doing precisely that. Antiproton beams have been demonstrated to be very efficient at cancer treatment. So far, only tested on mice, however.

[Bill Phil]

I used to work with PET scanners professionally; ex-neuroscientist. If you're looking for a citation, you're probably best off starting with Wiki (http://en.wikipedia.org/wiki/Positron_emission_tomography) and then drilling down into the references at the bottom of the article.

The basic way that a PET scan works is that you inject the patient with a mildly radioactive substance that is chemically attracted to the biological structure that you're interested in tracking (for example, FDG-PET brainscans use a form of radioactive glucose that is enthusiastically absorbed by active neurons). As the radiation decays, it produces positrons, which in turn produce bursts of gamma radiation when they collide with normal matter. The scanner can identify the source location of the gamma, which allows the measurement of where in the body the positron annihilation is occurring.

Making antimatter is easy; all you need is some radioactive decay. Pretty much every radiologically active thing is constantly surrounded by a transient cloud of the stuff. The hard part is in preventing it from immediately contacting normal matter and mutually annihilating.

That's not using antimatter, it's taking advantage of it, sure. But it's not USING antimatter, the antimatter is a byproduct and allows the detection of where the problem is indirectly.

It's taking advantage of the fact that antimatter does specific things, which is just a useful property of antimatter. WE can only produce a few particles of the stuff, and can only contain it for a short time.

Positrons from decay are surrounded by matter, so it can't be contained because of that.

[Wanderfound]

That's not using antimatter, it's taking advantage of it, sure. But it's not USING antimatter, the antimatter is a byproduct and allows the detection of where the problem is indirectly.

It's taking advantage of the fact that antimatter does specific things, which is just a useful property of antimatter. WE can only produce a few particles of the stuff, and can only contain it for a short time.

Positrons from decay are surrounded by matter, so it can't be contained because of that.

We're getting into semantics a bit, but outside of SF, that is how you "use" antimatter in science. Annihilating stuff just isn't that useful on its own; the correlations and implications are where the utility comes from.

As a sidenote:

Pretty much all medical imaging techniques (and a lot of other things in science) work like this. When you want to measure something that you can't observe directly, you find something that you can observe that has a reliable correlation with the thing you're actually interested in.

Brainscanning via fMRI measures disturbances in a magnetic field, that we infer into a measurement of blood oxygenation, which we further infer into an estimation of neuronal activity. EEGs measure electrical currents, MEGs measure the magnetic effect of those currents. Immunohistochemical neuroscience uses custom antibodies to visualise the occurrence of proteins that are associated with neuronal activity or injury, while high-pressure liquid chromatography (a standard technique for detecting changes in neurotransmitter levels) measures electrical resistance in the output of a pump and correlates the time of output with molecular weights. In none of these cases are you actually examining the neurons directly.

[Bill Phil]

We're getting into semantics a bit, but outside of SF, that is how you "use" antimatter in science. Annihilating stuff just isn't that useful on its own; the correlations and implications are where the utility comes from.

As a sidenote:

Pretty much all medical imaging techniques (and a lot of other things in science) work like this. When you want to measure something that you can't observe directly, you find something that you can observe that has a reliable correlation with the thing you're actually interested in.

Brainscanning via fMRI measures disturbances in a magnetic field, that we infer into a measurement of blood oxygenation, which we further infer into an estimation of neuronal activity. EEGs measure electrical currents, MEGs measure the magnetic effect of those currents. Immunohistochemical neuroscience uses custom antibodies to visualise the occurrence of proteins that are associated with neuronal activity or injury, while high-pressure liquid chromatography (a standard technique for detecting changes in neurotransmitter levels) measures electrical resistance in the output of a pump and correlates the time of output with molecular weights. In none of these cases are you actually examining the neurons directly.

You can stop with the educating, because I know that's how it's done.

Yeah, it is semantics. But I don't understand what your original point was. I was saying it was beyond us, and I was refering to its usefulness as a resource, such as in the ISV Venturestar.

What are you saying? It's already used? Well, that's technically correct. It is used, but not in the way I was talking about. Which is as a catalyst or a direct energy source.