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Earthquake Invisibility Cloak
BuzzSkyline writes "The same folks who brought us the tsunami invisibility cloak last year have now come up with an earthquake invisibility cloak. They show that a platform made of just the right configuration of elastic rings could make a structure invisible to earthquakes by effectively steering a quake around the structure. It doesn't work well for compression waves, but the researchers claim it could hide buildings from the slower-moving, more destructive shear earthquake waves. The research is due to be published soon in the journal Physical Review Letters."
You do realize that the point of this is to build it into all new buildings, right?
Additionally it's unlikely that the amount of extra energy from a few buildings would have a noticeable effect in the other buildings. Of course we can't violate the laws of physics, but when you're talking about that much energy and when most buildings are built to sustain much larger earthquakes than what's realistically going to happen it isn't worth worrying a whole lot about.
The illusion that medicine is well-compensated for the effort is just that -- an illusion.
Relative to what, exactly?
http://www.cejkasearch.com/compensation/amga_physician_compensation_survey.htm
There isn't an entry on that list below six figures. And I'd say the average is easily 250k plus.
An electrical engineer "1" in the 90th percentile (ie making more than 90% of his peers), according to salary.com makes 67k. Unless he gets promoted to management, (and does less engineering and more managing) he's going to have a very tough time cracking 6 figs.
A nuclear physicist, cracks six figures. But even his 90th percentile at 126k doesn't quite reach the expected STARTING wage of "Pediatrics - Adolescents" - 130k, probably the lowest number on that list.
It's not the sheer magnitude of an earthquake that actually determines damage. Damage should be much more correlated with how much of the energy gets dissipated into a building or other structure.
Try looking at it like this: If you are standing out in a field when an earthquake hits, you personally may be the only thing on top of the ground, that could absorb any energy from that part of a wave passing through the whole area. Just you. Now if you are on the bottom floor of a big concrete parking garage, that whole garage and all the cars in it could absorb various parts of the energy, so if energy really determines the damage, you are safer on the bottommost floor of that garage than out in the open. Doesn't seem at all likely, does it?
Energy in physics is sometimes defined as the ability to do work. A lot of energy means a lot of work can happen, not that it invariably happens where you might expect, or even happens at all. (and yes, knocking down a tall building counts as work for most definitions in physics, even if gravity does most of the job once you get it good and started).
So, we have a structure which doesn't couple strongly to the energy of a quake wave. You can say it deflects the wave, or channels it, or lots of other verbal descriptions, but the point is, not a lot of the energy of the wave passes into the building. That energy could go on to get absorbed by another building, but alternately it could keep on going until it dissipates in the relatively empty countryside many miles from the city. Not absorbing a lot of the locally available energy doesn't mean the energy has been deflected to target some other building, or somehow focused. It also doesn't necessarily mean the energy has changed overall direction, or that you have created more turbulence in the earthquake waves, or lots of other things that could possibly happen but maybe really won't. To see if any of them are really probable, you have to do math, not reason from a verbal model that is already just an approximation.
Who is John Cabal?
> With an earthquake, isn't the building less solid than than Earth?
IANASiesmologist (but I play one on TV (ok, I can't back that up))
Actually, sometimes it isn't. Depending on the properties of the quake (strength, depth, etc), the ground itself (particularly soil) acts a lot like a liquid. A "slab" house might float while a bedrock based building may have major structural issues due to compression of the major structural elements. This is one of the big reasons that building in earthquake zones have "floating" structural members. They need to be able to "move" independently, relative to the ground, because the ground doesn't move uniformly. One particularly inventive solution stored inertia in a giant multi-ton sphere suspended in the top of a skyscraper. This reduced lateral movement while maintaining flexibility of the structure.
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