Clue to earthquake lightning mystery | Hacker News Reader

Clue to earthquake lightning mystery

bbc.co.uk

43 pointsColinWright22 comments

preface: I'm doing a PhD in granular physics.

I was at a conference two years ago where this experiment (flash of light from a tub of flour) was discussed. This is not new, or news.

It was also linked, by another speaker at the conference, to earthquake lightning in the following discussions.

It may not be news to experts in the field, but I think it's news to most of us.

Unless I've missed something, it also seems to be news to Professor Troy Shinbrot of Rutgers University.

No, Troy is the link. http://phys.org/news/2012-06-rutgers-granular-slip-documents... (So after 2 years he still has no idea on how it's happening?)

Ah, if they were writing about it 2 years ago already, then their result may be the one that was repeated in front of me - curse the mainstream media's "new! new!" language in their copy.

the abstract from that paper is very informative as to the context:

"It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials."

Interesting that this is likely also very related (or the exact same) as when peeling scotch tape, that mechanical action produces x-rays.

What about the thought of Chi; could the electric impulses commonly thought of for centuries by martial artists and meditators be an electrical output of some mechanical function of the body?

Chi - only of breaking your arm.

The energy being released is from fracture, i.e. bonds breaking, in all but the granular case. Indeed, even granular pack breakup could well involve sympathetic local charging, especially for packs gradually compressed and stressed like soils.

I was referring to the Scientists describing their findings. They are clearly not already members of the granular community as I know it.

I remember reading (a long time ago) that occasionally static electricity in deserts caused headaches, which could be dispelled by earthing oneself.

I found this on Wikipedia just now (http://en.wikipedia.org/wiki/Desert#Dust_storms_and_sandstor...): "During a sandstorm, the wind-blown sand particles become electrically charged. Such electric fields, which range in size up to 80 kV/m, can produce sparks and cause interference with telecommunications equipment. They are also unpleasant for humans and can cause headaches and nausea. The electric fields are caused by collision between airborne particles and by the impacts of saltating sand grains landing on the ground. The mechanism is little understood but the particles usually have a negative charge when their diameter is under 250 μm and a positive one when they are over 500 μm."

Do you know if these phenomena are connected?

Same origin: friction (just like the balloon and your hair) causes the particles to charge up. Where it earths itself is the only difference.

Update:

OK, perhaps I should have googled Troy Shinbrot, as he was the guy who presented the work I saw. Apologies!

I worked this out after a simple google image search for his name. The image from this article (sorry, it's more of an advert in fact) is the one that sparked my memory, you'll see why:

http://www.nj.com/entertainment/index.ssf/2012/04/rutgers_da...

Tupperware tends to be plastic, the BBC article doesn't really mention if they tested different container materials with the same substrate. For example, would a wooden container yield the same results with flour as the "soil"?

Their abstract mentions the use of 3 types of "soil" - organic powders, polymeric disks and glass particles. Does anyone have access to the full article to see if they repeated the experiment with differing containers?

I had the same thought. The box in the photograph looks like acrylic, which has a strong triboelectric potential.

https://en.wikipedia.org/wiki/Triboelectric_effect

Here's a paper by the authors:

http://arxiv.org/abs/1307.2489

"The shear cell is nominally 125 cm × 26 cm in size, and the particles are weakly confined by either a 0.5 mm clear flexible PVC or 1.4 mm thick acrylic sheet in order to suppress out-of-plane buckling. The sheet is wiped with a damp cloth before the experiment to minimize triboelectrification."

Exactly. Also, it's a bit hard to determine but the container looks closed. In my mind that would provide another surface to enhance the triboelectric potential you mentioned.

Edit: Thanks for that link. Why don't they remove the triboelectric contribution altogether by using a more sensible container for obtaining reliable results?

Interesting. I'd like to see further research done to test if large voltage spikes like this could explain animal behavioral patterns before earthquakes and tsunamis.

What kind of equipment is required to detect those spikes? Can it be done at home as an experiment?

The basics of detecting lightning is to measure the potential difference (voltage) between the earth and the air. A simple home experiment you can do to detect it is to create Franklin bells:

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

http://www.instructables.com/id/Franklins-Bells/

In the case of this, instead of the higher voltage being in the sky (hence why lightning discharges down), the higher voltage is in the earth. You can measure the voltage between the bells (multimeters usually only go up to a few hundred volts, so wouldn't be enough) at various locations across a large area, and see if any anomalies come up before an earthquake :) You might get annoyed by the ringing first though...

Check out "The Scientific American Book Of Projects For The Amateur Scientist" - C. L. Strong describes quite a bit of this in the section "The earth sciences". The schematics date from 1960 (tubes, not transistors) but you'll find updates around the web.

http://www.sciencemadness.org/library/books/projects_for_the...

If this is a phenomenon, could it used to generate electricity? What the lower layer of ships were filled with a flour like substance? Would that produce anything useful as the ship rolled? Or what if we float tubs of this stuff on waves?

> If this is a phenomenon, could it used to generate electricity?

In theory yes. You could gain electricity by rubbing millions of plastic rods on cats. Whether that's an efficient way to produce electricity is a different matter: Power plants that use the power of waves exist, at least in experimental stages and they're probably much more efficient than a boat filled with flour.

Also, note that although producing Volts means electricity it doesn't mean necessarily that you have any significant amount of energy.

You may have an incredibly large amount of volts from a source that's not even capable to light a bulb for a few seconds.

see for example a zamboni pile: http://en.wikipedia.org/wiki/Zamboni_pile potential is in the KV range while the current is in the nano ampere range. That thing is weaker than most most modern batteries when it comes to powering things.

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