String Theory's Extra Dimensions Must Be Less Than Half the Width of a Human Hair

Scientific American ^ | January 16, 2007 | JR Minkel

[SunkenCiv]

Researchers found that the same law governing the gravitational pull between planets continues to work when objects are separated by as little as 56 micrometers. The finding rules out extra dimensions of 44 micrometers or larger, they report in this week's Physical Review Letters. Discovering extra dimensions with the relatively huge size of a few micrometers would offer spectacular confirmation for string theory, the still unproved body of equations that may unify gravity with the normally incompatible realm of quantum physics. "Even though we haven't seen anything, these results put boundaries on what people can legitimately propose," says experimental physicist and study author Eric Adelberger of the University of Washington. "Testing the inverse square law [meaning Newton's law of gravity] is the bombproof way to look for extra dimensions." ...Adelberger says they might be able to get down to a few micrometers, but it would be very tough. "As the dimensions get smaller and smaller, the force [they cause] gets smaller much faster," he says. The payoff could be worth it, though. Sundrum says that if extra dimensions failed to turn up at that distance, it would likely prune off that branch of string theory.

[SunkenCiv]

Perhaps analogous to Mitchelson-Morley?

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Image: EOT-Wash Group, University Of Washington

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[SunkenCiv]

[Jaysun]

Woo! Concentrating on this stuff for too long can make you into a paranoid schizophrenic! It's too deep so I'm going to think about something else..........puppies.

[SunkenCiv]

That puppy you're holding? It's made of string. Bwa-ha-ha.

[GoLightly]

Someone thought of that before you did...

http://pilot.cit.duke.edu/blogs/physics55/hdb2/archives/000164.html

[uglybiker]

Woo! Concentrating on this stuff for too long can make you into a paranoid schizophrenic!

Or worse...

[Jaysun]

That puppy you're holding? It's made of string. Bwa-ha-ha.

No. It's a slush puppy and it's made of (pause for effect) love. (now weeping uncontrollably and allowing damn-your-eyes craziness to take over).

[Jaysun]

That reminds me of a bizarre conversation I had recently. I was talking to a guy that I went to school with and he told me that one of his coworkers "shot his brain (very singular) out." His brain? Don't you mean brains? And don't you mean blew his brains out?

But I guess he's right. We just have one brain so it should be singular. And the word "shot" is probably better than "blew". So anyway, be careful not to shoot your brain out while cleaning your guns.

[woofie]

Just as I suspected

[GoLightly]

As long as you don't start hearing Whos, you should be okay.

[GoLightly]

So anyway, be careful not to shoot your brain out while cleaning your guns.

Wouldn't you only have to worry about the gun that goes off while you're cleaning it or do we only get into dangerous territory if we're dealing with more than one gun? And, for some reason, I'm picturing the need for a mightly large hole to blow the whole thing out.

[EarthBound]

Oh! You've got a string theory ping list Sunken? Can you add me to this one as well? thanks.

[Jaysun]

Wouldn't you only have to worry about the gun that goes off while you're cleaning it or do we only get into dangerous territory if we're dealing with more than one gun? And, for some reason, I'm picturing the need for a mightly large hole to blow the whole thing out.

Fine point. Be careful not to shoot a piece of your brain out while cleaning your gun.

[SunkenCiv]

Yeah, I must have lost my brain. :') There were quite a few string theory threads [rimshot!] so it just kind of grew out of that.

[SunkenCiv]

This topic article is about such a test. :')

"But has anyone devised a way of testing 'string theory?' Or is it one of those fascinating and, even elegant, speculations destined to go unresolved forever?" [Continental Soldier, 11/26/2006]

http://www.freerepublic.com/focus/chat/1744159/posts?page=11#11