Static Electricity Defies Simple Explanation 86
sciencehabit writes: "If you've ever wiggled a balloon against your hair, you know that rubbing together two different materials can generate static electricity. But rubbing bits of the same material can create static, too. Now, researchers have shot down a decades-old idea of how that same-stuff static comes about (study). '[The researchers] mixed grains of insulating zirconium dioxide-silicate with diameters of 251 micrometers and 326 micrometers and dropped them through a horizontal electric field, which pushed positively charged particles one way and negatively charged particles the other. They tracked tens of thousands of particles—by dropping an $85,000 high-speed camera alongside them. Sure enough, the smaller ones tended to be charged negatively and the larger ones positively, each accumulating 2 million charges on average. Then the researchers probed whether those charges could come from electrons already trapped on the grains' surfaces. They gently heated fresh grains to liberate the trapped electrons and let them "relax" back into less energetic states. As an electron undergoes such a transition, it emits a photon. So by counting photons, the researchers could tally the trapped electrons. "It's pretty amazing to me that they count every electron on a particle," Shinbrot says. The tally showed that the beads start out with far too few trapped electrons to explain the static buildup, Jaeger says.'"
Re:it's explained in the study (Score:5, Interesting)
Re:it's explained in the study (Score:5, Interesting)
How difficult would it be to re-run the same procedure with fully dehydrated particles? Is this a 'just bake them under a modest vacuum for a bit' situation, or are these values of 'small' and 'adsorbed' the sort of thing where getting the water out would be a moderately heroic endeavor?
Difficult, you'd need to run the entire process under an ultra-high vacuum. For reference, you to get water monolayer formation times greater than a second, you'd need pressures of roughly less than 10^-7 torr, or 10^-10 atmospheres. For reference (if WolframAlpha is to believed), the ISS is exposed to a pressure of about 10^-11 atmospheres. Molecular/ion pumps can get that low a pressure, so it's not impossible, just difficult.
Re:it's explained in the study (Score:4, Interesting)
The title is unfortunate (it's clickbait)... At the end of the paper, they point out that small amounts of water adsorbed on the surfaces of these oxides should create H+ and OH- ions in a density that does explain the static generation effect.
No, that's just one of two alternative hypotheses mentioned at the end of the article. The second is transfer of the zirconium itself between the particles. There could be other ideas. The point of this study is only to eliminate the widely assumed electron-transfer hypothesis, not to establish any alternative. So the title is quite accurate.
I love when modest science take the air out of pom (Score:4, Interesting)
I am not saying that they are a bunch of halfwits, not at all, just that I respect the scientists who are clear on the idea that there is so much that we don't know. I don't respect the scientists who ever even hint that we are "reaching the end of science".
If I were to have become a Physicist (my unrequited dream) this is all I would study, the little mysteries. I suspect that it would be harder to get a grant for static electricity than for something involving military devices, but based upon previous history, a discovery this fundamental would probably have huge technological repercussions. I have long thought that some of the biggest experiments such as the monster Fusion reactor in Europe (ITER) would find that money so much better spent on a zillion little plasma experiments. I think the budget blew well past $20 billion. I am 100% sure that if you gave 4000 of the world's top physicists $500,000 per year for the next decade that they would make leaps that would then make a fusion reactor a snap. My worry is that as they get the ITER turned on that they will find that they are having to wrap it in more and more duck tape to solve one problem after another. If this starts to happen during an economic crisis then the project will be shut down and all that time and effort will have been wasted. But think of the pomopsity of the scientists who are running that project. They will be able to preen themselves and go to all the best conferences where officials will swoon over them hoping to get a tiny piece of the budgetary pie. But they will go an entire career without ever turning the machine on so it doesn't matter if it works or not for them. A functioning machine would be a bonus. A functioning budget is all they care about; oh and good PR.
Again I am willing to bet that more good science could end up coming out of these grains of sand than the whole of ITER.