highfrequency 5 months ago

> The magic of animal electrostatics is all about size. Large animals don’t meaningfully experience nature’s static—we’re too big to feel it. “As humans, we are living mostly in a gravitational or fluid-dynamics world,” Ortega-Jiménez said. But for tiny beings, gravity is an afterthought. Insects can feel air’s viscosity. While the same laws of physics reign over Earth’s smallest and largest species, the balance of forces shifts with size.

Very cool article. For example: butterflies accumulate a positive charge when beating their wings, which causes pollen to jump through the air toward them when they land on flowers.

  • Swizec 5 months ago

    Similar to this, one of the most mind-blowing papers I’ve read was Life at Low Reynold’s Number about how at the microorganism level water is virtually solid and inertia does not exist.

    https://www.damtp.cam.ac.uk/user/gold/pdfs/purcell.pdf https://swizec.com/blog/week-9-life-at-low-reynolds-number/

    • hermitcrab 5 months ago

      When you are very big (like an elephant), gravity is all important and surface tension barely matters.

      When you are very small (like an ant), it is the other way around.

      Toss a mouse from a building. It will land, shake itself off and scamper away. But if similarly dropped, “… a rat is killed, a man is broken, a horse splashes.” So wrote J.B.S. Haldane in his 1926 essay "On Being the Right Size." https://www.edge.org/response-detail/27082

    • MrLeap 5 months ago

      Inertia doesn't exist? Wow that's hard to visualize. Perhaps the world does converge on cellular automata as you zoom in

  • tommiegannert 5 months ago

    The same question scales outwards. Are there forces taking over from gravity at galactic scale? Like, perhaps the galaxy filaments and voids come about due to something we can't even comprehend. It seems unlikely that humans just happen to be working with the force at the largest "scale."

    How complicated would it be for a small insect to explain gravity, if they're not normally affected by it in their daily routine?

    I recently thought about something similar: it seems like at certain scales, things turn into spheres, based on applicable forces. And then there are in-between regions with chaos. Atoms seem mostly round. Humans are not. If planets and stars are at the next spherical scale, are there even larger structures out there that once again show spherical nature, once you're past galaxies, clusters and filaments?

    • hnuser123456 5 months ago

      Since black holes grow with their radius proportional to mass (not volume), larger black holes are less dense. The current estimates for the size and mass of the universe fits right on the line of that curve of critical density.

    • deciplex 5 months ago

      The universe itself, if bounded, might be a hypersphere.

  • tomcam 5 months ago

    Username particularly appropriate

rsynnott 5 months ago

> A few years after Ortega-Jiménez noticed spiderwebs nabbing bugs, Robert’s team found that bees can gather negatively charged pollen without brushing up against it.

It's arguably kind of weird that this is just being noticed now. I suppose possibly modern camera equipment helps, for purposes of actually _seeing_ it happen...

amelius 5 months ago

If insects can build up 5 kilovolts while flying, then why can I zap flies with a fly-zapping tool that presumably runs at a similar or lower voltage?

  • codeflo 5 months ago

    It's not a bad question, these units of measurements are always a bit confusing. You can similarly ask why for humans, rubbing a balloon is harmless, although that builds up 30 kV of static electricity, while touching a 230 V power socket can kill you.

    Voltage is merely the "pressure" that charged particles experience. Voltage alone tells you nothing about how much charge is actually available once electricity is allowed to flow. And that's where the harm comes from. For static electricity, when you touch something, you get maybe a microcoulomb, once, and it's gone. For a power socket, you get up to 16 coulombs per second continuously.

    • BoxOfRain 5 months ago

      Hence the saying 'it's the volts that jolt and the mills that kill'.

      • tgv 5 months ago

        But can e.g. 3V DC kill? Perhaps by using the body's resistance, but I have the idea that the effect would be different from say 220V AC, which affects the nerves.

        • rtkwe 5 months ago

          Not generally, remember Ohm's Law I = V/R. Internally the body has a resistance of ~300 Ohms as a rough rule while our skin is 1000-10000 depending on the condition and contact area involved.

          So 3V isn't going to pose any real risk unless it's applied internally and right across a critical nerve leading to your heart or a muscle directly on the heart. For reference pacemakers are generally set to 2-3 volts. Applied externally up to ~12V is generally considered low enough voltage there's a low risk of truly adverse effects.

        • BoxOfRain 5 months ago

          You'd have to really try.

          10 milliamps across your heart can kill but using Ohm's law we can calculate 3V / 0.010 A to get a resistance of 300 ohms. This means you're probably still going to have a bad time if you apply it directly across your heart during open-heart surgery but other than that 3 volts just isn't enough to drive a lethal current through your skin.

          • jcdny 5 months ago

            Which is why if caught in a lightning storm you should crouch with feet together and why I try very hard to only use one hand when doing something that might have the potential to shock me.

        • mecsred 5 months ago

          Depends how it's applied and what's sourcing it. 3v does basically nothing to dry skin, but would be quite bad on wires implanted in your chest across your heart.

      • howenterprisey 5 months ago

        I've usually heard "volts hurt, amps kill".

    • ocfnash 5 months ago

      As a kid, the alliterative mnemonic we were taught was "current kills".

      • dmd 5 months ago

        "It's the volts that jolt but the mils [milliamps] that kills."

        • metalman 5 months ago

          thats all theory thing is that I mess with large two volt(nominal) storage cells,the largest are over 250lbs and sit like dumb beasts,waiting to oblige anyones low voltage requests,hundreds of amps on tap be nothing to bolt ,some nice shiny copper handles to the terminals and mist them down with some warm salt water I also mess around with microscopes,and compared to bugs,humans are very poorly made,so many tiny things are flawless living perfection,and some like wolf(jumping) spiders are smart,smart enough that they see us seeing them,and are ok with that one thing that I have observed that plays into the static electricity thing,is that many of the tiny critters that I watch,are impecably clean,no dust or dirt on them at all,perfectly clean,unlike a human finger,which is one zillabutt uggly thing,under magnification

          • dmd 5 months ago

            are you ok man

  • chmod775 5 months ago

    When they fly, there's no current. They just have potential compared to ground. Also presumably their electrical charge is very low and there's going to be hardly any amps when they discharge.

    In the same vein, if your carpet gives you a static shock, that's likely going to be thousands of volts. But obviously there isn't actually a lot of energy stored (all you did was convert some friction), so there's next to no amperes, little work the electricity can do, and thus no harm.

  • brk 5 months ago

    For many of the same reasons that birds can land on high voltage lines without risk of being electrocuted. A flying insect has stored voltage with no path to ground, or any point with low resistance and lower potential.

    When you hit a flying insect with a zapper you are supplying a high potential and low potential electrode. The insects body completes the circuit and the stored voltage is routed through the insect, rendering it a flightless blob of goo.

palata 5 months ago

> Webs deformed instantly when jolted with static from flies, aphids, honeybees, and even water droplets. Spiders caught charged insects more easily.

This is all so fascinating!

hermitcrab 5 months ago

>spiders take flight by extending a silk thread to catch charges in the sky

I did some amateur research on spider ballooning many years ago and I believe part of the lift comes from rising air dragging along the silk thread. From my calculations, it wasn't enough to lift the spider on its own, but it might allow the spider to fall slower than the convective air currents were rising.

ysofunny 5 months ago

but if anybody regular worries about the (quite new) abundance of EM radiation one's the nutjob

  • matt_j 5 months ago

    The way I understand it, there is one EM field and photons of various frequencies travel in that field: radio, microwave, infra-red, visible, ultra-violet, x-ray, gamma.

    We are awash with EM radiation of almost all frequencies from the universe. A little 5G probably isn't our biggest problem.

    Besides, this article is more about electo-static forces, and how, when you're very small, these are much more significant than the gravitational force, which makes sense.

  • hermitcrab 5 months ago

    We've always lived amongst abundant EM radiation.

    • devm0de 5 months ago

      Not the man made kind, which are different from natural sources and greatly increase the background EM fields we live in.

      • hermitcrab 5 months ago

        EM radiation is defined by it's wavelength and amplitude. Whether it is from a 'natural' source is completely irrelevant in terms of the effect it has.

        I guess humans have changed the mix of wavelength we are exposed to a bit. E.g. more RF radiation from phones and base stations. But I'm not sure how significant those changes are in the overall 'background EM fields we live in'.

paulorlando 5 months ago

"They were using a toy wand that gathers static charge to levitate lightweight objects, such as a balloon." -- How much science progresses through play.

smolder 5 months ago

This makes me wonder if cave dwelling species which live in darkness have any specially evolved features dealing with electric charge.

HPsquared 5 months ago

See also magnetic sensing (magnetoreception) in animals used for orientation and navigation.

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

There are other electromagnetic type things too, like use of light (camouflage, bioluminescence, eyes) and electricity (electric eels, bioelectrical cues for stem cell differentiation).

EDIT: Also the literal electrical potential within cells: the membrane potential, that is the voltage difference between inside and outside every cell.

An interesting area!

w33n1s 5 months ago

Really interesting article. Highlights something I think is so cool but have a hard time really articulating: how even within our own 3+1 dimensions, just changing your scale is an entirely different experience.

  • mcosta 5 months ago

    Some forces are O(n^2). Other are ratios between volume and mass.

    Also there are critical points. You can't have any arbitrary mass of hydrogen in space, at some point it collapses ant starts to burn.

lofaszvanitt 5 months ago

All this in 55 pages of text. Wired, never changes. They rob your time with unnecessary wall of text. blablablbla