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You are getting sleeeeeeepy ...

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Re: You are getting sleeeeeeepy ...

#41

Post by lutusp »

raldi wrote: post #38
lutusp wrote: post #9

Earlier quoted context omitted.

> Did the construction lights have light sensors? The construction lights were light sensors. The reason they got into synchronization is because they were triggered to break down at a specific time by the flashes of light from the other lamps. In a system like this, the voltage on all the lamps is increasing because a charging current is applied to a capacitor that'a connected across the lamp. But the specific time…

Can you explain what you mean by "break down" in this context?

As the voltage across the gas increases, at some point it causes electrons to leave their valence orbits and travel through the gas (the gas becomes a plasma). That's a "breakdown" if the threshold-crossing causes a sudden, abrupt increase in overall current in the gas, and if the system has a negative resistance trait (one in which the relationship between voltage and current contradicts the usual expectations).

The idea in this case is that the photoelectric effect (Einstein) also can cause an electron to leave its valence orbit. Therefore if the voltage in the gas is high enough to almost cause a breakdown or "avalanche", any extra electrons released by photon interactions may trigger the avalanche in advance of the time it might otherwise have happened.

So you have the possibility of an avalanche caused by the electric field, and you also have some electrons liberated by the photoelectric effect. The breakdown point is determined by both populations, not just one.

Re: You are getting sleeeeeeepy ...

#42

Post by DrStalker »

huhtenberg wrote: post #19
ColinWright wrote: post #17

Earlier quoted context omitted.

I've always been told this, and it's always seemed plausible, but it was declared busted by Mythbusters. Having said that, as quoted elsewhere, the Millennium Bridge across the Thames in London did exhibit resonant swaying as pedestrians crossed it, and extra dampers needed to be added. Added in edit ... Auto-hoist, petard-wise. It seems some people have assumed that I meant that this never happens, and cannot ever h…

> declared busted by Mythbusters Oh, goodie, case closed then. Mythbusters have this tendency to "bust" stories that revolve around rare and unique circumstances by running just few experiments. Obviously that's a flawed approach.

And then there was the time they tested shock absorbers on a car's bumper exploding in a fire and sending the bumper flying away. They couldn't replicate it.

They spoke to a woman with scars on her legs from a bumper that hit her after shock absorbers on a burning car exploded and sent the bumper flying away.

So they called it confirmed, since it could happen, they just couldn't get everything right in the lab.

I know it's entertainment first and science second, but a complete reversal of policy just because there is someone you're not willing to look at and call a liar? Weak.

Re: You are getting sleeeeeeepy ...

#43

Post by antimora »

lutusp wrote: post #3

I have a story seemingly remotely associated with this, but actually very much the same. Years ago, at highway construction sites, sawhorses would be erected that were equipped with flashing lights for safety after dark. In those days the flashing lights were gas-discharge lamps connected to a simple charging circuit consisting of a capacitor connected across the lamp and charged by way of a resistor -- a very simple…

This reminded me of Synchronous fireflies. There are at least 2 kinds on them (Asian and North American).

Here is the night time video: http://www.youtube.com/watch?v=a-Vy7NZTGos

Here is an article on this: http://www.nps.gov/grsm/naturescience/fireflies.htm

Re: You are getting sleeeeeeepy ...

#44

Post by femto »

raldi wrote: post #4

Order from chaos! And without any external source of energy. I wonder what other physical phenomena emerge this way. Magnetic fields, I bet.

Feynman started by investigating the wobbles of a spinning plate, and ended up with Quantum Electrodynamics. Looking at the metronome video, I found myself thinking, "There's got to be something deep there".

It'd be really cool if the metronomes turned out to be a model of the quantum vacuum, and the patterns running though the array of oscillators turned out to be virtual particles winking into and out of existence. (Hey, I can dream, can't I?)

---

edit: spelling

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