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Comment by vanderZwan | Hacker News Reader

This somehow reminds me of the fact that you can produce (surprisingly high-quality) x-rays by unrolling scotch tape in a vacuum chamber[0][1]. I wonder if it turns out to be related in any way. Thunderstorms aren't a vacuum of course, but I dunno, maybe all that frozen hail being thrown around can bumping into each other still involves a similar underlying mechanism somewhere.

[0] https://www.nature.com/articles/nature07378

[1] https://www.youtube.com/watch?v=-o66AYhEIsU&

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It was suprising to me when I heard it. How could we not know it would happen before hand? Doubt explanation of it needs new laws of physics, item is common place and yet we were all caught off-guard. Wonder who different other planets even in our own solar system are, even if we know all the laws of physics and chemistry that guide those reactions; never mind planets in other solar systems

What about guitar pedal velcro tape?

[0] "Correlation between nanosecond X-ray flashes and stick–slip friction in peeling tape" (2008) https://www.nature.com/articles/nature07378

> Triboluminescence is a phenomenon in which light is generated when a material is mechanically pulled apart, ripped, scratched, crushed, or rubbed (see tribology). [...] Triboluminescence is often a synonym for fractoluminescence (a term mainly used when referring only to light emitted from fractured crystals). Triboluminescence differs from piezoluminescence in that a piezoluminescent material emits light when deformed, as opposed to broken. These are examples of mechanoluminescence, which is luminescence resulting from any mechanical action on a solid. [...] See also:

> - Earthquake light: https://en.wikipedia.org/wiki/Earthquake_light

- re: gold from earthquake-induced piezoelectricity in quartz: https://news.ycombinator.com/item?id=41442489

- re: sustainable alternatives to quartz countertops: https://news.ycombinator.com/item?id=36857929 :

> [...] make recycled paper outdoor waterproof vert ramps, countertops, siding, and flooring; but not yet roofing FWIU?

> - Sonoluminesence: https://en.wikipedia.org/wiki/Sonoluminescence

You don't even need a vacuum to get a decent amount of xrays. Two drills going through a roll of scotch, reel to reel, will generate enough x-rays to take a rudimentary xray image of a hand.

When objects collide or are separated, aren't we really just witnessing tiny chemical reactions, all involving the absorption and/or release of energy?

I think that's a reasonable question, but no, I wouldn't say that that is the case. A chemical reactions is by definition the kind that involves changing the chemical composition of the molecules involved (yes, that's a bit handwavy, I'm not a chemist).

The process that causes tape to produce to x-rays when peeled in a vacuum in this example does involve a change of energy states, but not in a way that we'd consider a change in chemical composition.

What is holding the tape to itself, what is making it sticky, if not chemistry?

For pressure-sensitive-adhesive tape (cellophane tape) it's mainly fuzzy static cling--wetting and van Der Waal's forces [1]. Wetting is when two substances (even solids) intermingle at their interface. van Der Waal's force is when a negatively-charged area of one molecule lines up the a postively-charged area of another.

[1] https://science.howstuffworks.com/innovation/everyday-innova...

I see, so you're saying static cling "at a distance" is different to the interaction of positive and negative charges in a chemical reaction?

IANAChemist, but to extend the cheesy analogies chemical bonds are like joint custody in a divorce; two atoms share one or more electrons. If it's split more or less evenly then it's called a covalent bond. If it's stacked in one atom's favor then it's called ionic. If it's kind of in a gray area in the middle then its called a polar covalent bond. [1]

Adhesion, even due to electrostatic or van Der Waal's forces, doesn't cause an electron to be shared [2].

To switch up the analogy (again, IANAC): as I understand it chemical bonds are like a couples thing; if you invite one you have to invite the other, and if you are interested in replacing a chemical bond with one of the atoms you need to first tear the couple apart. That's because chemical bonds share an electron; to share a particular electron with a new atom you need to stop sharing with the first one. (Sort of. I believe it's a lot more complicated than that, with group marriages and such.)

Adhesion is more like a friendship thing. You might hang out together, but there's no intimiate involvement. The electronic bonds are still available, so each each substance can do its normal chemical reaction thing with other atoms.

[1] https://en.wikipedia.org/wiki/Ionic_bonding

[2] Despite my previous cheesy analogy, electrostatic adhesion is the real static-cling force, not van Der Waal's. (But electrostatic adhesion isn't what makes sticky tape sticky, van Der Waals is.) The former is between entire molecules or groups of molecules, one group having a total positive charge compared to the other. van Der Waal's is pin-point attraction between local differences in molecular charge distribution, and each molecule in total might be electrically neutral. For example, a neutral water molecule has two highly-positive areas near the Hydrogen atoms and a highly-negative region away from them.

No. "Gamma rays" in modern scientific usage has a specific meaning: radiation coming from the nucleus or from annihilation reactions (electron + positron is considered a gamma source despite not involving a nucleus), not from the electrons. The energy bands actually overlap, you can't always tell whether a given photon is without understanding it's source. (The lowest energy gamma rays actually fall in the UV part of the spectrum.)

And what they're saying is the energy of the lightning is acting as a particle accelerator. aka atom smasher. And there's a surprising level of atom smashing going on in the big thunderclouds.

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