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Credit rustworthiness

by xaritas

This is a cool little science project. All you need are some rust filings and a card with a magnetic stripe on it. Probably not a card you expect to re-use.

… finely powder some rust and then blow it over the magstripe on your credit card and you can see the zeroes and ones encoded on it by the stripes where the magnetic forces attract the ferrous particles.

Check out the picture in the original article. Neat.

(From “Use rust particles to reveal the data on your credit-card’s magstripe“, via Boing Boing.)

May 14, 2010   Comments Off

The ball is not a ball

by xaritas

This is a really interesting fact, combined with some speculation. Apparently very intense magnetic fields, focused inside the brain, can cause visual hallucinations of glowing orbs and lines. The speculation is that at least part of the time, when people think they are seeing “ball lightning” they are actually standing close enough to a magnetic field induced by lightning to stimulate the same hallucination.

Focus the field in the visual cortex, for example, and the induced eddys cause the subject to ‘see’ lights that appear as discs and lines. Move the the field within the cortex and the subject sees the lights move too.

All that much is repeatable in the lab using giant superconducting magnets capable of creating fields of as much as 0.5 Tesla inside the brain.

But if this happens in the lab, then why not in the real world too, say Joseph Peer and Alexander Kendl at the University of Innsbruck in Austria. They calculate that the rapidly changing fields associated with repeated lightning strikes are powerful enough to cause a similar phenomenon in humans within 200 metres.

I assume this works by inducing current between synapses when the magnetic field moves. The experience would be unique to each person since it depends both on the precise orientation of the field, and the unique way each person’s brain is wired. So this technology could never be used to cause mass, shared hallucinatory perception. Presumably.

By the way, the Wikipedia article linked above describes creating a synthetic form of ball lightning using a microwave. Anybody got a spare microwave?

(From “Technology Review: Blogs: arXiv blog: Magnetically-Induced Hallucinations Explain Ball Lightning, Say Physicists“, via Slashdot.)

May 12, 2010   Comments Off