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You are getting sleeeeeeepy ...

blogs.discovermagazine.com

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Re: You are getting sleeeeeeepy ...

#31

Post by derekp7 »

tgb wrote: post #22

The linked article claims that metronomes start 'pairing up' with their nearest neighbors saying that "strongest forces on a metronome will initially be from its nearest neighbors." But if the forces are spread by the string-suspended table swaying back and forth, I wouldn't expect adjacent metronomes to be significantly more connected than further away ones. Instead, I wonder if we just happen to be better at notici…

Probably the initial synchronization happens due to vibration, which would be felt by the closest neighbor. Then the macro synchronization happens due to the table swaying.

Re: You are getting sleeeeeeepy ...

#32

Post by pitchups »

ColinWright wrote: post #17
huhtenberg wrote: post #15

Earlier quoted context omitted.

> troops are ordered not to walk in step, because of the stress it places on the bridge Not really, not because of the "stress." The walking rhythm may match the natural oscillation of the bridge thus resulting in a resonance effect. At least that's what they taught us in high school.

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…

Another famous example would be the collapse of the Tacoma Narrows Bridge in 1940, widely believed to have been caused by forced resonance. However, as per Wikipedia, the real cause of the collpase was aeroelastic flutter.

Video of bridge collapse : http://www.youtube.com/watch?v=xox9BVSu7Ok Wikipedia: http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge#cite_note...

Re: You are getting sleeeeeeepy ...

#35

Post by alan57 »

alan_cx wrote: post #7

There is a place in the UK where this happens with spooky regularity with people walking. There is a covered walk way between Waterloo and Waterloo East railway stations. The mob of people enter it unsynchronised and by the time they leave, they are usually all synchronised. I assume this happens in many other places too, I just haven't been every where else to see!!!! I always assumed this was because people can hea…

I think your assumption is right on. Just try to listen to music when you walk and not end up lock-step with the beat.

Re: You are getting sleeeeeeepy ...

#36

Post by ChuckMcM »

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.

Uh, no. The article points out the metronomes are on a suspended table. Each metronome adds energy to the table in phase with its cycle, as more metronomes get into phase, their summed energy edition begins to push back on other metronomes bringing them all into alignment. By the end of the video you can see the table is oscillating exactly out of phase with the metronomes as expected by that point.

Re: You are getting sleeeeeeepy ...

#37

Post by raldi »

ChuckMcM wrote: post #36
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.

Uh, no. The article points out the metronomes are on a suspended table. Each metronome adds energy to the table in phase with its cycle, as more metronomes get into phase, their summed energy edition begins to push back on other metronomes bringing them all into alignment. By the end of the video you can see the table is oscillating exactly out of phase with the metronomes as expected by that point.

What difference does that make? The metronomes and table are a closed system, so the fact that energy is transferred between them is moot.

I think lutusp's explanation makes a lot more sense: that when the metronomes sync up, they're at a lower energy level. They spend energy to decrease entropy.

Re: You are getting sleeeeeeepy ...

#38

Post by raldi »

lutusp wrote: post #9
jonmrodriguez wrote: post #5

Earlier quoted context omitted.

How would your headlight desynchronize the construction lights just by shining on them, if it was powered by a separate source? Did the construction lights have light sensors?

> 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?

Re: You are getting sleeeeeeepy ...

#40

Post by gryphonic »

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?

Plasma breakdown. The voltage across the gas eventually accelerates electrons fast enough that they can ionize atoms when they collide, and an avalanche occurs creating a plasma and light. Same effect as a neon lamp
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