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Antihydrogen Trapped For 1000 Seconds

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Re: Antihydrogen Trapped For 1000 Seconds

#91

Post by InclinedPlane »

VladRussian wrote: post #83
othermaciej wrote: post #71

Earlier quoted context omitted.

We know two things about dark matter: - It doesn't interact electromagnetically. - It does interact gravitationally and produces extra gravitational attraction beyond the electromagnetically interacting matter we know about. - It is dispersed throughout galaxies. The first property rules out baryonic antimatter as dark matter, since that would interact electromagnetically. The last two properties rule out anything th…

>We know two things about dark matter: while we don't know whether it exists at all. Whatever phenomena are explained by DM are also easy explained by molecular hydrogen (i.e H2) which is almost not detectable. [The hydrogen we know about in the space is atomic - H, and there should be orders of magnitude more of molecular one than atomic when you have atomic at such interstellar space conditions]

We know that dark matter cannot be baryonic matter (atoms) for two reasons. First, models of the big bang that have been confirmed by experiment closely bound the total amount of baryonic matter in the Universe. Second, dark matter doesn't seem to behave the same way that baryonic matter behaves (normal matter clumps, dark matter doesn't appear to do so).

Re: Antihydrogen Trapped For 1000 Seconds

#92

Post by InclinedPlane »

Typhon wrote: post #69

By the way, there's something I've been wondering about for a long time. I read somewhere that there are no antiphotons and antimatter emits light just the same as normal matter. So, I assume that there's no way to tell whether a photon was emitted by antimatter or by matter. Therefore, how do we know distant galaxies aren't made of antimatter ? Maybe there's an obvious answer, but as far as I know, the only thing we…

Empty space isn't completely empty, even between galaxies. There are traces of gas, almost entirely Hydrogen, between galaxies. If there were entire galaxies made of anti-matter then the areas where their clouds of inter-galactic anti-gas contacted normal inter-galactic gas would be rife with emissions due to annihilations. The amount of matter should be enough to be detectable even at tremendous distances.

Re: Antihydrogen Trapped For 1000 Seconds

#93

Post by ww520 »

Typhon wrote: post #69

By the way, there's something I've been wondering about for a long time. I read somewhere that there are no antiphotons and antimatter emits light just the same as normal matter. So, I assume that there's no way to tell whether a photon was emitted by antimatter or by matter. Therefore, how do we know distant galaxies aren't made of antimatter ? Maybe there's an obvious answer, but as far as I know, the only thing we…

If antimatter are repulsed by gravity, they might be in the outer shell of the universe being pushed further away. If antimatter also repulsed among themselves (??), then they won't have a chance to come together to create antimatter star.

Most people believe antimatter attract just like matter, so it's a moot point.

Re: Antihydrogen Trapped For 1000 Seconds

#94

Post by StavrosK »

jacques_chester wrote: post #88
StavrosK wrote: post #39

Earlier quoted context omitted.

So you're saying that this has fantastic military applications? Interesting...

The military don't like antimatter weapons because they are fail-dangerous. They require active stabilisation. If a nuke fails, nothing happens. If antimatter containment fails, your entire arsenal of antimatter weapons go up at once. For a similar reason, nitroglycerin is strangely unpopular for both civilian and military purposes.

Interesting, so you are suggesting some sort of gun that creates antimatter in a remote location. That's a great idea!

Re: Antihydrogen Trapped For 1000 Seconds

#96

Post by VladRussian »

InclinedPlane wrote: post #91
VladRussian wrote: post #83

Earlier quoted context omitted.

>We know two things about dark matter: while we don't know whether it exists at all. Whatever phenomena are explained by DM are also easy explained by molecular hydrogen (i.e H2) which is almost not detectable. [The hydrogen we know about in the space is atomic - H, and there should be orders of magnitude more of molecular one than atomic when you have atomic at such interstellar space conditions]

We know that dark matter cannot be baryonic matter (atoms) for two reasons. First, models of the big bang that have been confirmed by experiment closely bound the total amount of baryonic matter in the Universe. Second, dark matter doesn't seem to behave the same way that baryonic matter behaves (normal matter clumps, dark matter doesn't appear to do so).

>...models of the big bang that have been confirmed by experiment ...

to put it mildly, it is a very overreaching statement.

>Second, dark matter doesn't seem to behave the same way that baryonic matter behaves (normal matter clumps, dark matter doesn't appear to do so).

double whammy - we couldn't observe dark matter and we couldn't observe its clumps.

Or consider it another way - while it supposedly have gravitational attraction, and have no other strong interactions known, we somehow should suppose that its non-clumping, ie. gaseous/cloudy/spread-around state is still a normal thing.

Re: Antihydrogen Trapped For 1000 Seconds

#97

Post by jacques_chester »

StavrosK wrote: post #94
jacques_chester wrote: post #88

Earlier quoted context omitted.

The military don't like antimatter weapons because they are fail-dangerous. They require active stabilisation. If a nuke fails, nothing happens. If antimatter containment fails, your entire arsenal of antimatter weapons go up at once. For a similar reason, nitroglycerin is strangely unpopular for both civilian and military purposes.

Interesting, so you are suggesting some sort of gun that creates antimatter in a remote location. That's a great idea!

A weapon that could create antimatter at a remote location would be a particle accelerator. One that could create non-trivial amounts of antimatter would cause far more damage from its direct consequences than from antimatter. By factors of millions or billions.

It would be heinously expensive and would require the kind of energy input that only gigawatt-grade nuclear power plants could provide. Rather than using a complicated, failure prone and inefficient way to transform nuclear fission into destruction, it would be simpler and more effective to lob a nuke with the same amount of uranium or plutonium.

Hence, for your day-to-day megadeath needs, thermonuclear weapons will remain the tool of choice for the foreseeable future.

Re: Antihydrogen Trapped For 1000 Seconds

#98

Post by StavrosK »

jacques_chester wrote: post #97
StavrosK wrote: post #94

Earlier quoted context omitted.

Interesting, so you are suggesting some sort of gun that creates antimatter in a remote location. That's a great idea!

A weapon that could create antimatter at a remote location would be a particle accelerator. One that could create non-trivial amounts of antimatter would cause far more damage from its direct consequences than from antimatter. By factors of millions or billions. It would be heinously expensive and would require the kind of energy input that only gigawatt-grade nuclear power plants could provide. Rather than using a c…

Unless we could convince the enemy to use that weapon!

I guess thermonuclear weapons are cheaper, though...

Re: Antihydrogen Trapped For 1000 Seconds

#99

Post by andrewflnr »

Fargren wrote: post #77
enko wrote: post #53

Earlier quoted context omitted.

Well, let's see what the data says. I confess I want the universe to surprise and confound. I want the theories to be wrong, I want reality to be stranger than fiction. That would be awesome! Or I am wrong, in which case I'll happily pay out[1]. I'm a layman, as if that wasn't obvious, and it will be a much-needed physics lesson. Win-win. [1] If in Australia, payout will take the form of alcohol credits at an establi…

Well, it would be really cool and confounding if gravity made antimatter move sideways. But I don't think that's likely.

Indeed, considering that there are 360 degrees of sideways. Which one? :)

Re: Antihydrogen Trapped For 1000 Seconds

#100

Post by jacques_chester »

StavrosK wrote: post #98
jacques_chester wrote: post #97

Earlier quoted context omitted.

A weapon that could create antimatter at a remote location would be a particle accelerator. One that could create non-trivial amounts of antimatter would cause far more damage from its direct consequences than from antimatter. By factors of millions or billions. It would be heinously expensive and would require the kind of energy input that only gigawatt-grade nuclear power plants could provide. Rather than using a c…

Unless we could convince the enemy to use that weapon! I guess thermonuclear weapons are cheaper, though...

To build either nukes or particle accelerators you need physicists, who are the kind of non-team-players likely to point out that nukes would work better.
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