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Comments: 169 +- Science: Antimatter In Lightning on Saturday November 07, @08:15AM
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Soulskill
on Saturday November 07, @08:15AM
from the doc-brown-can-now-power-his-warp-drive dept.
from the doc-brown-can-now-power-his-warp-drive dept.
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AMESN writes "The Fermi Gamma-ray Space Telescope, launched last year, detects gamma rays from light years away, but recently it detected gamma rays from lightning on Earth. And the energy of the gamma rays is specific to the decay of positrons, which are the antimatter flavor of electrons. Finding antimatter in lightning surprised researchers and suggests the electric field of the lightning somehow got reversed."
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Reversing the polarity of the electron discharge? (Score:5, Funny)
The decay of positrons in the largescale discharge of electronic particles may very well lead to gamma ray emissions, however it is crucial to understand the energy output required to reverse the polarity of the discharge so that we can reproduce the phenomenon in a controlled laboratory.
Or else the Romulans will destroy the Federation.
Re:Reversing the polarity of the electron discharg (Score:5, Funny)
Parent
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Dr. Peter Venkman: That's bad. Okay. All right, important safety tip. Thanks, Egon.
Re:Reversing the polarity of the electron discharg (Score:5, Funny)
You're all off base.The explanaion is much simpler.
Did anybody shout "SHAZAM!" nearby?
Parent
Re: (Score:2)
What's a stream? Is it like a subspace tachyon polarization discharge eddy?
Re: (Score:3, Funny)
Anyone who watches Star Trek knows that any time you want to solve technical problems or achieve new developments, all you need to do is reverse the polarity or invert the phase. Why didn't the folks behind the LHC try this? It's have saved billions of dollars and years of delays! ;)
Re:Reversing the polarity of the electron discharg (Score:4, Funny)
Anyone who watches Star Trek knows that any time you want to solve technical problems or achieve new developments, all you need to do is reverse the polarity or invert the phase.
You forgot to reroute through the main deflector.
Parent
Re: (Score:3, Funny)
Just out of curiosity, (and sorry for derailing the thread) who is spending these billions of dollars to build and repair the LHC?
The Vulcans. Duh. Keep up next time.
Crossover (Score:2, Interesting)
Not that surprising (Score:5, Interesting)
Apparently they've detected gamma ray energies up to 20 MeV from thunderstorms, so given that amount of energy involved I wouldn't think it's that surprising that electron-positron pairs might be created in the process since an electron only has a mass of .511 MeV. The thunderstorms are basically operating like natural linear accelerators.
reversal schmersal (Score:4, Insightful)
Antimatter in lightning does not suggest that the electric field got reversed; that's nonsense. The electric field is a vector, and it can point in any direction.
What it does suggest is either that the few positrons created or brought by cosmic rays are somehow concentrated by lightning, or that the strong electric fields in lightning are actually pulling a few positron-electron pairs out of the quantum electrodynamic vacuum. The first explanation is probably ruled out unless positron decay gamma rays are also seen all over in the atmosphere, just not as densely concentrated as in lightning.
The second explanation is perfectly possible, if the electric fields in lightning are simply strong enough over large enough volumes of space. Any potential difference greater than 2 m c^2/e will in theory produce positrons and electrons from nothing; this is called 'the Schwinger Effect'. But the rate is ridiculously low unless the field is enormous, and it has not yet been observed. Relatively straightforward calculations would allow one to estimate what sort of electric fields lightning would need to involve, for the observations to be due to the Schwinger Effect.
Re: (Score:2, Funny)
quantum electrodynamic vacuum
positron decay gamma rays
You're good!
Re: (Score:2, Funny)
reversal schmersal
the Schwinger Effect
Aaahh... a bit of German makes every scientific topic cool. ;)
We only lack a "färbottenärr Krruppstahl Gammastrrahlänn-Krriegsmaschinenapparraturrr" in there somewhere. Jawohl!
Wundabar! Jahaha!
Re: (Score:2, Interesting)
Fusion reactions seem more likely.
Been looking a long time (Score:2, Informative)
Researchers have been looking for the tell-tale 0.511 MeV photons for decades in lightning storms. The idea is that a lightning channel could act like a natural particle accelerator. So electron-positron pairs could be created. But they have never been seen before from what I understand. But maybe these particles were created in much larger lightning bolts or perhaps the emissions are preferentially directed upwards into space ... dunno. Very interesting.
This was first observed in 1971 (Score:5, Informative)
It’s a surprise to have found the signature of positrons during a lightning storm, Briggs said.
No, it's not.
There is a long history of observations and theorizing about gamma ray flashes from lightning strikes and ball lightning, starting in the early 1970's :
Is Ball Lightning caused by Antimatter Meteorites? [nature.com]
D. E. T. F. ASHBY, C. WHITEHEAD, Nature 230, 180-182 (19 March 1971).
This has also been observed in connection with "sprites [harvard.edu]".
And from thunderclouds [arxiv.org] without lightning [arxiv.org].
Oh, and it's also been observed from space before :
RHESSI Observations of Terrestrial Gamma-Ray Flashes [harvard.edu]
Now, not all of these reports include a positron annihilation signature at 511 KeV. But, 511 KeV emissions were explicitly reported from lightning in the 1970's [nature.com]. And, considering that lightning / thunderstorm related gamma rays are routinely observed with energies up to 10 MeV, there is plenty of energy to create positrons, and so I wouldn't be surprised if all of these reports included the positron annihilation line (or, at least the ones with sensitivity in that energy range).
Re:This was first observed in 1971 (Score:5, Funny)
Did you stumble into this forum by mistake? Come back when you have some baseless conjecture or a conspiracy theory.
Parent
Re:This was first observed in 1971 (Score:4, Funny)
Not to mention a goddamn car analogy.
Parent
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I am in Japan, and jet-lagged - I mean to say
Now, not all of these abstracts report include a positron annihilation signature at 511 KeV.
I have read these papers (and others) and IIRC 511 KeV reports are fairly common, but I don't have them in front of me to be sure.
Re: (Score:3, Interesting)
And, considering that lightning / thunderstorm related gamma rays are routinely observed with energies up to 10 MeV, there is plenty of energy to create positrons, and so I wouldn't be surprised if all of these reports included the positron annihilation line (or, at least the ones with sensitivity in that energy range).
Considering that pair production starts becoming significant at gamma energies above 5 MeV (threshold 1.022 MeV), I would be very surprised if there weren't some 0.511 MeV gammas from thunderstorms. It is also likely that the positrons could be formed by interaction between high energy electrons and matter.
I would think that the gammas are produced in conjunction with sprites (cloud to ionosphere) rather than normal cloud to ground strokes.
Re: (Score:3, Informative)
Why not indeed ?
This sounds reasonable to me :
The lightning associated gamma rays can be inferred as due to bremsstrahlung associated with electrons released moments after the return stroke and the likely radiation associated with radioactive decay products in the interactions of protons generated in the lightning with the atmospheric constituents
(from Jayanthi et al., 2006 [harvard.edu]).
Although the previous reports of lightning induced fusion from Slashdot [slashdot.org] are intriguing.
Whoa there, cart before horse? (Score:3, Interesting)
Could it be the other way around, that cosmic rays trigger lightning? So the timing is just a coincidence?
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No. These observations were made with a telescope. That means that they know what direction the gamma rays came from. Cosmic rays don't come up out of the Earth.
Cross section of lightning? (Score:5, Interesting)
Does anyone know what the cross section of a lightning bolt looks like? I've always wondered if forces akin to the skin-effect are trying to spread out the electrons while it's constrained in a tube of plasma. Is it round? Is it a sheet? What's the electron density like? What sorts of pressures would you expect in the center of a bolt?
Just curious... but I'm unable to find a google hit and too dumb to simulate it.
Re: (Score:3, Interesting)
I think we have a pretty good understanding of plasma. Just look at a florescent or neon lamp. A lightening bolt is a tube of mostly positively-charged nitrogen ions in a cloud of electrons. The super-heated gas glows brightly as
Re:just wondering... (Score:4, Funny)
The LHC was obsolete [newscientist.com] before it was even constructed.
It never stood a chance.
Parent
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But does it know it's obsolete?
Will it tell us how to build the next one?
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The purpose of LHC is not to find antimatter (at least not primarily). It's purpose is to find the higgs boson and you don't need LHC to make antimatter
Re:just wondering... (Score:5, Funny)
Parent
Re:Time to modulate the shields (Score:5, Funny)
What the fuck? You just graduate from the Academy?
Modulating the shields leaves you vulnerable to phased weapon attacks.
"The only way" is to reorient the tractor beam vectors to generate a harmonic subspace bubble around the vessel.
Fucking amateur.
Parent
Re:Time to modulate the shields (Score:5, Funny)
Just to steer the conversation back on topic, your harmonic subspace bubble isn't going to do jack to protect you from the gamma-ray discharge from an antimatter/matter conversion on it's perimeter. In fact it might cause a toroid-effect and trap the gamma-rays inside your shields, interfere with your sensors and might even take some crucial subsystems offline.
Only a combined strategy of cryptographic spread-spectrum modulation of shields combined with aggressive targetted tractor beam vectoring can keep you safe from localized radiation effects and energy weapons. You really need to keep abreast of the technology in these matters or you could leave yourself, your crew, and very valuable data and equipment at risk.
Posted anonymously for obvious reasons.
Parent
"other means" would be more than "unexplained"... (Score:5, Insightful)
If they're detecting 511KeV gammas generated by "the direct conversion of electrons to energy" not involving positrons, then, yeah, it would be a hell of a discovery, seeing as how it would blow away all those stodgy conservation laws and symmetries and whatnot.
Parent
Re:"other means" would be more than "unexplained". (Score:5, Funny)
>Remember: In science, NEVER be arrogant, or too convinced of your theories.
Wow, you haven;t been around academics much have you?
I recall an old joke:
"How many PHDs does it take to change a light bulb?
One to unscrew it, one to pull the chair from underneath him"
Parent
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...it could also mean the direct conversion of electrons to energy by some other unexplained means.
then for that energy we would need 2 electrons, not one.
Either way, it would be a hell of a discovery, potentially leading to matter-to-energy conversion power generation. To hell with fusion power, this is better!
well isn't fusion a way of matter-to-energy conversion power generator?
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then for that energy we would need 2 electrons, not one.
511 KeV is the mass-equivalent energy of a single electron or positron, and annihilation results in two gamma photons heading off in different directions.
well isn't fusion a way of matter-to-energy conversion power generator?
Yes, but it's not as clean as direct annihilation would be. It generates neutrons which make the materials used for containment radioactive.
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Yes, but it's not as clean as direct annihilation would be. It generates neutrons which make the materials used for containment radioactive.
Depends on the starting elements. Among others, He3+He3->He4+2p+E. No free neutrons generated, only protons and energy.
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As to "All current fusion designs", that's because we're still trying to make it work in the first place and neutron producing reactions are easier to start with right now. If they could eliminate neutrons from the process now, they would, as it would increase reactor life. Also, energy is not purely extracted by neutrons. If it was, the plasma would heat up indefini
Re:clean fusion (Score:4, Interesting)
Well, some of the polywell/Farnsworth enthusiasts hope to harness boron-11/proton fusion. In the most common case, that produces three energetic He nuclei (alpha particles), each carrying two positive charges at several MeV. Surround the reaction zone with collector plates, and you extract the energy directly as high-voltage, low-current DC.
In practice, of course, it's not that simple.
Parent
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No, of all our technology to produce power it still involves boiling water.
Tapping these nuclear sources directly would be a step forward.
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No, of all our technology to produce power it still involves boiling water.
Except for internal combustion, photovoltaic solar, molten-sodium solar, hydroelectric, wind, or using an alternator instead of a break to provide resistance to excersie equipment.
Yeah, so, aside from all of those, everything uses boiling water.
Re:what exactly did they detect? (Score:5, Informative)
Boiling water isn't a direct electrical source either, it's all about energy conversion. The easiest way to convert heat into electricity is to first convert it to kinetic energy. The easiest, cheapest, and safest way to convert heat energy to kinetic energy is to boil water and creat a pressure differential to drive a piston or turbine or what have you. It's very effective, and there isn't any compound likely to do the job better than H2O that isn't also prohibitively expensive.
Heat is the easiest form of raw energy to produce, and if boiling water is the easiest, cheapest, and safest way to convert heat energy into kinetic energy (which is then trivial to convert to electrical energy at very high conversion rates).
Heat engines are also still the most efficient form of energy conversion available to us. A typical modern steam turbine generator will convert close to 50% of the heat energy to electricity, and in some applications can convert as much as 90%. Combustion engines are typically in the 30% range, but getting higher, though they have a theoretical hard limit at 37%. Photvoltaic is coming along, but frankly it's still young and the readily available PV cells compare poorly to combustion and turbine engines. The theoretical limit for a single cell is about 40% efficiency (with light concentrators), but new techniques are working around that limit (they use multiple materials in the cell, effectively combining several cells in one) and the current record is around 43%.
The big problem PV has vs combustion or turbine engines is energy density - the fuel sources the later two methods use are significantly more energy dense than plain sunlight. Sunlight throws a lot of energy everywhere, but only a little in any particular spot. Concentrating it effectively has always been a problem.
Parent
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Fusion releases the binding energy of the fused nucleus. It's like what happens in a chemical reaction except the mediating force is the (residual) strong force instead of the electromagnetic force, so you tend to get more energy. That amount of energy is still very small compared to the total energy represented by the mass of the reactants. It's not really matter to energy power generation because the mass that gets converted to energy is not really "matter" but rather potential energy. You're talking
Re:what exactly did they detect? (Score:5, Informative)
From the first paragraph of the article:
During its first 14 months of operation, the flying observatory has detected 17 gamma-ray flashes associated with terrestrial storms -- and some of those flashes have contained a surprising signature of antimatter.
In other words, they have detected 17 gamma-ray flashes due to lightning, and some of them have the signature of antimatter (i.e. the electron-positron annihilation).
I'm not sure how that's not exactly what you're saying they didn't say. Just because they didn't say 511 KeV? If 511 KeV is the signature of electron-positron antimatter collitions, and they've found the signature of antimatter collisions in some (not all) of the storms, wouldn't that suggest they are seeing 511 KeV bursts?
Here's more:
During two recent lightning storms, Fermi recorded gamma-ray emissions of a particular energy that could have been produced only by the decay of energetic positrons, the antimatter equivalent of electrons.
It seems pretty specific about what they are seeing, it is simply stated in a high-level language that the common interested-but-not-knowledgeable reader can understand.
This is essentially an online science news magazine, not a journal for published papers seeking peer review. They are only going to give you the gist of the information at a high-level, and from there if you have better knowledge of the subject you should have an automatic deeper insight into what they might be seeing.
It's not like it's some amature job either, the space telescope was built to find this sort of thing, so finding these signatures is not like some wack job pop-sci company pushing nonsense in a press conference to attract investors before folding in a few years.
Parent
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Umm... This would be hydrogen + hydrogen = deuterium + positron? That makes sense... Though to be generating enough positrons to show detectable levels of gammas from space, that would be a huge discovery.
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so if it's even possible within the laws of physics it's probably at least a thousand years before we can do anything like that, and i don't see any reason t
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Well you wouldn't 'see' it. :)
Re:Electron-Proton Collisions? (Score:5, Informative)
No, you don't get annihilation from electrons and protons.
You do get radiation, if things are energetic enough. If the electron becomes bound to the proton, you get emissions at one of the Hydrogen lines.
If, for example, the electron went all the way to the Hydrogen ground state, you would have emissions at the limit of the Lyman Series [wikipedia.org], up in the hard UV at 91 nanometers.
If things are more energetic, you will get electrons and protons combining to form free neutrons. These will decay [gsu.edu] (this decay is called beta decay) and release gamma rays at 782 KeV, but since the half life of free neutrons is 10.3 minutes, this will be really spread out in time and hard to see. Free neutrons have been directly detected from lightning strikes, so some of this is presumably going on.
Parent
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So you are saying that electron-proton collisions probably do occur, but do not lead to the observed gamma radiation TFA mentions?
Re:Electron-Proton Collisions? (Score:5, Informative)
Electron-proton collisions will not lead to a 511 KeV line. That's due to electron-positron collisions.
Parent