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"Ballooning" Spiders Use Electrostatic Forces To Generate Lift
KentuckyFC writes "Many types of small spider release threads into the air which then lift and carry them significant distances. Biologists have found them at altitudes of up to 4 km. The conventional thinking is that the threads catch thermal air currents which then carry them away but this does not explain how spiders perform their trick even when there is little or no wind. Now one physicist says the explanation is the atmosphere's natural electric field which has an average downward-pointing magnitude of 120 Volts per metre. He calculates that a strand of silk need only gain a negative charge of around 30 nanoCoulombs to lift a spider. That explains how the spiders take off on windless days, how they reach such great heights and how several strands can lift heavier spiders of up to 100 milligrams."
Does this explain how Spider-Man can shoot and then swing on webs that are attached to... what? Clouds? The International Space Station?
"Of course, Gorham’s ideas will need to be tested by actually measuring the charge on gossamer spider silk as it is generated. That’s an experiment for an enterprising biologist to take on."
Some people die at 25 and aren't buried until 75. -Benjamin Franklin
Stories like this are the reason i frequent /.
This really bugs me.
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To me stuff like this is what proves evolution. There is no one in their right mind who could sit there and convince me that such an obtuse solution to move from point A to point B is "by design", vs. random evolution.
The bat signal itself doesn't fit with physics.
My parents have owned a searchlight rental business for 30 years now. For the first Batman movie they were asked to put a bat signal cutout on the searchlight to simulate the bat signal. The thing is that searchlights have too high a candlepower and the light just bends around the cutout. The light spreads more the farther away from the searchlight. It looks cool when shown against a wall, but far out in the sky it simply doesn't work. The physics of light doesn't allow it.
The sky webs read "crispy bacon". Poor Wilbur.
The earth's magnetic field is almost certainly unrelated. The magnetic field is generated internally due to us having a molten iron core. This atmospheric electrical field comes from the bulk transport, separation, and friction of huge air masses - like the kind that give rise to thunderstorms. There's interplay between the two, especially during a solar storm (e.g., aurorae), but you couldn't freeze the magnetic field by tapping the atmosphere.
As for why we can't tap that, I could only speculate. 120 V/m sounds like a sizable field - strong enough that we ought to be able to feel it. On the other hand, the E-field in an ordinary capacitor is many orders of magnitude greater (10s of volts, perhaps, but separated by just microns). You can get a greater E-field from peeling scotch tape off its roll.
Also bear in mind that an electric field, by itself, is not a store of energy. In order to make use of that field, you need to have charge traverse that field - a flow of electrons. If we think of the atmosphere between stratosphere and ground like a giant capacitor, its stored energy is 1/2 * C * V^2. The V term might be very large (120 kV/km, squared!), but if the C is tiny, then you end up without much energy. And do not conflate power and energy: you can get quite a spark from a discharging capacitor (or a lightning bolt!) - great instantaneous power - but it doesn't last. Unless there's some source to continuously replenish the charge separation, you may not be able to tap much energy. I suspect that the available energy is very diffuse; more diffuse than, say, the kinetic energy of wind that we are able to capture with turbines. You would probably need kilometer-sized antenna arrays to capture much useful power.
The rule in my house is that if you have more than four limbs, you are a bug , and you belong outdoors. This policy is clearly stated on the signs underneath each door.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Life imitates glitching :)
I mean this sounds exactly like some games that have double-jump and other glitches. Officially nothing is supposed to float unless it's lighter than air, but in reality there's about six (known) ways to exploit aspects of the world that were 'never intended' to end up with flight. Much like with videogame physics some animal figures out a trick, then keeps iterating until that trick is an art, then a science, and finally a way of life :)
One household for a month, or one trip anytime into the past or future with your hovering time machine!
I've just read that one bolt of lightning powers one household with all their energy needs for a month. I'm not too sure how accurate that is; but I think we'll need a lot more than that.
I will try to plug the numbers in. Let's see how this goes.
According to the physics.org toast power article, a lightning packs "over five billion joules of energy". I will round that down to 5 billion. A watt is the same thing as "joules per second". A month has 60 * 60 * 24 * 30 = 2,592,000 seconds. Then, 5 * 10^9 J / 2,592,000 s = 1929 J/s. This means that we can run the house at a constant power consumption of 1929 watts. Converted to a standard kWh number that would be 1389kWh per month.
That's pretty much on the spot. It would indeed be enough to run a house of a small family for one month, accounting electrical heating running around winter.
I will have to read the research article because the press article doesn't explain it. a dipole charge would not move in a linear gradient field. it would require a second order curvature to the gradient to make it move. thus it's irrelevant that the linear field is 120 v /meter. what would matter is the derivative on that.
Some drink at the fountain of knowledge. Others just gargle.
I'll believe this when someone takes some spider silk, charges it up, and it can lift an inanimate object of weight of a spider in still air.
I wonder if the same concept could be used to help relieve stress on the cables of space elevators? How much charge would it take to offset the weight of some amount of cable and can solve a measure of the strain problem?
Of course, Gorhamâ(TM)s ideas will need to be tested by actually measuring the charge on gossamer spider silk as it is generated.
Rather than trying to test it directly, just modulate the field in a room containing such a spider.
If the spider and its silk has a net charge you should be able to steer it around the room, land it where you want it, and measure the charge by the spider's response to the ambient field you're modulating. The attitude of the spider/silk system in the modified field will also give you the distribution of charge vs. weight on the spider and its silk.
If the spider and its silk doesn't have a net charge it will just hang there and blow around in the air currents.
(Of course the fanning out of the silk already proves the silk itself has a substantial charge.)
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