The Volokh Conspiracy
[Jonathan Adler, October 20, 2006 at 8:29am] Trackbacks
Not Quite Invisible:

The NYT declares "Scientists Take a Step Toward Invisibility." Well, kinda. Some scientists have developed what could more accurately be described as a cloaking device in that it appears to deflect a given frequency of electromagnetic waves without generating distortions, shadows, etc. of the sort that could be detectable. In practical terms, as I understand the story, this could lead to a "cloaking" device that could make an object invisible to radar. Actual invisibility is still a long way off, however.

Syme:
Not quite true. This invention is not a stealth device (which do make objects invisible to radar). Rather, the scientists have demonstrated that they can cause microwaves to bend around an object such that an observer of the microwaves cannot tell the microwaves have been deflected. Theoretically, this process could apply to light waves as well, hence, invisibility claims are somewhat close to the truth.
10.20.2006 10:48am
CJColucci:
But a truly invisible person would be blind. Maybe you could still rob a bank by feel, but there goes the trip to the women's locker room.
10.20.2006 11:07am
MS (mail):
Syme's right. If this could one day deflect all visible frequencies of electromagnetic waves, then you'd be invisible.
10.20.2006 11:16am
logicnazi (mail) (www):
What you would need to do is make all human visible wavelengths of light bend around the object and then use some other wavelength to look out of your invisibility shiled (some artificial viewing device).
10.20.2006 11:49am
Hoosier:
Doubglas Adams riffed on invisibility in one of the "Hitchhiker's" books. Scientists discovered that the process of making an object invisible was demanding that it was always a better choice to just do without it.
10.20.2006 12:28pm
Jeremy Pierce (mail) (www):
The article says it would be very complex to do this with visible light, but it seems to treat it as if there's no theoretical obstacle to doing so. I'm not sure the same is true of expanding it to larger-scale objects, because some of what they are doing seems to be dependent on the fact that they're working on an extremely small scale.
10.20.2006 12:53pm
Dick King:
The big deal is making it work over a span of wavelengths.

The blindness issue isn't all that bad, actually, because the human eye has such a range of acceptable brightness. If 0.1% of the light reaches the protected object, that wouldn't be very noticable but on a reasonably bright day the user would be able to see. However, that light which the shield doesn't deflect would probably be distorted unmercifully.

We manage to see out of our fencing masks almost as if they weren't there, and they block at least 3/4 of the incoming light and probably significantly more. Fencing room designers don't even feel themselves obligated to make the rooms particularly bright.

-dk
10.20.2006 1:05pm
Wild Pegasus (mail) (www):
We'll beat the Romulans to the technology by two centuries.

- Josh
10.20.2006 2:11pm
dearieme:
"Actual invisibility is still a long way off": how could one tell?
10.20.2006 3:15pm
Kent G. Budge (mail):
As a physicist, I've felt socially invisible for years.
10.20.2006 4:47pm
David M. Nieporent (www):
Doubglas Adams riffed on invisibility in one of the "Hitchhiker's" books. Scientists discovered that the process of making an object invisible was demanding that it was always a better choice to just do without it.
Hoosier, that's because there was an alternative: the Somebody Else's Problem Field.
10.20.2006 6:22pm
Zubon (www):
"Actual invisibility is still a long way off": how could one tell?
Well, I haven't seen anything invisible lately...
10.20.2006 7:46pm
EricT:

Maybe you could still rob a bank by feel, but there goes the trip to the women's locker room.

The trip to the women's locker room 'by feel' could still be pretty rewarding.
10.20.2006 7:52pm
Lev:
Sometimes one wonders if the US Constitution isn't invisible to the Supreme Court.
10.20.2006 11:37pm

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