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Remember Invisibility Cloaking and the Robot rope climbers ?

Remember those two previous posts ?

Well now I have tracked down the definitive movie on each. No more guesswork - straight from the horses mouth.

First the NASA-sponsored light-powered robot rope climbers at the competition in New Mexico this weekend. Practicing to climb a 30,000km cable up into space ? Well here is a video showing one of them making it to the top of the 200 ft test climb:

Robot climber video is here (page down a bit)

But what about the invisibility cloaking ?

Now that I see the video it looks totally overhyped to me. Any wave can pass round obstructions which are not substantially bigger than the wavelength, and pass through multiple gaps smaller than the wavelength. Now I see the pictures of the wavefronts and the multiple large concentric gapped rings round the small object to be cloaked, the acclaimed reduction in waveform disturbance seems to verge on the insignificant to me. I see that the diameter of the object is in fact about one wavelength, and therefore we would expect the radiation to pass round it fairly successfully with no cloak, and this is exactly what we see.

invisibility cloak
Do you see a dramatic difference between the waves leaving on the right ? Is the fancy cloaker at the top doing much, or do the waves make it round fairly well without ? I think they do. To do the same with visible light the object would have to be a sub-microscopic speck. The microwave illumination here is 8.5GHz, with a wavelength of 3.5cms, close to the object diameter.

Furthermore, all this bragging about fancy metamaterials is highly misleading. Reading the paper itself tells us that this allegedly amazing shield was in fact fabricated by a local printed circuit company, using bogstandard etched copper technology. To make it very small would indeed require metamaterials (read “is currently impossible”), but this isn’t small, and doesn’t use them. Though the publicity does everything possible to imply that amazing new metamaterials are actually used and part of the “breakthrough”

The more I read, the more appalled I am at this shameless hype.

Remember, the sky is blue precisely because the red and yellow light has long enough waves to pass round all the tiny particles, but the blue light finds them too big to get round, and gets deflected out of the straight line from the sun, and bounced into our eyes. This “particle” is just small enough for its waves to more or less make it round, and the “cloak” helps a tiny bit. That’s all. Ugh !
Have a look at the detailed video on the overhyped cloaking device

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Protected from Alzheimer’s by your wicked, wicked past ?

Nothing to do with the Sun or anything Solar, but I just couldn’t resist this oh so reassuring snippet:

“Evidence suggests that people who regularly smoked marijuana in the 1960s and 1970s rarely develop Alzheimer’s disease, said Wenk, ………”

Oh dear, no justice, eh ? Or is there ?

Here is the link to the full article in Cosmos

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