Category Archives: Physics

Having the Hot Hand is a Bad Thing

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Researchers show ATM theft by thermal imaging

The research team from the University of California, San Diego, found that their cameras picked up a PIN entered on a keypad more than 80 percent of the time if used immediately. If used a minute later, it picked up the digits about half the time. After 90 seconds, the chance of extracting the digits dropped to about 20 percent. They tested the frequency using custom software that they wrote to automate their analysis.

Not sure how big of a threat this would be for someone who walks up to a machine. I haven’t had to use an ATM is a while, but in the transactions I’ve done it seems that there is a reasonable (from a security standpoint) delay between PIN entry and finishing your transaction. I expect the threat would be from a camera mounted along with a skimmer.

Compressed Again

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Compressed 02

I combined everyday soap bubbles with exotic ferrofluid liquid to create an eerie tale, using macro lenses and time lapse techniques. Black ferrofluid and dye race through bubble structures, drawn through by the invisible forces of capillary action and magnetism.

You Break it, You Bought it

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Violating relativity by breaking equivalence

It’s fairly well-known that general relativity and quantum mechanics don’t get along, so the mock surprise that this happens is a little tedious, but that’s the state of (science) journalism. Once you get beyond that, it’s pretty neat.

Numerous experiments, measuring all types of phenomena, have proven that the equivalence principle holds. However, a new thought experiment published in a recent version of Physical Review Letters demonstrates that, depending on how you measure temperature, a scientist in the sealed laboratory could tell where she is. On the surface, this result would seem to suggest that the equivalence principle it not valid under all conditions, but there is a wrinkle—the researchers here suggest making a local quantum mechanical measurement. The fact that quantum mechanics is an inherently non-local phenomenon may provide a way of cheating the prerequisites that Einstein put on his equivalence principle.

One caveat here is that this is still a thought experiment, and it’s still possible that someone else will come along and show that it’s not a problem. One needs to recognize that papers are a way that scientists “think out loud” and get feedback. No doubt that this idea went through discussions and then peer-review, which are steps that should weed out obvious loopholes and problems, but when you’re at the edge of GR and QM there might be more subtle concepts lurking.

One thing to note in the article is the ambiguity/error they have presented in explaining GR

Einstein proposed the equivalence principle in 1907, a full nine years before his publication of general relativity. The idea, however, guided the development of general relativity. When combined with Einstein’s theory of special relativity, it gave rise to the prediction that clocks will run at different speeds in gravitational fields with differing strengths, and that light would be bent by gravitational fields.

If strength means the acceleration (or force), and that’s usually what is meant, then this is wrong. Time dilation depends on the gravitational potential, which is the depth of the potential well. The acceleration is the slope of the side of the well. It’s possible to be very deep in a well and have a large amount of time dilation while having a local value for g that is small.

One More Thing to Deal With

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OK, an earthquake, a hurricane and now a frikkin’ supernova.

Berkeley Scientists Discover an “Instant Cosmic Classic” Supernova

At a mere 21 million light-years from Earth, a relatively small distance by astronomical standards, the supernova is still getting brighter, and might even be visible with good binoculars in ten days’ time, appearing brighter than any other supernova of its type in the last 30 years.

“The best time to see this exploding star will be just after evening twilight in the Northern hemisphere in a week or so,” said Oxford’s Sullivan. “You’ll need dark skies and a good pair of binoculars, although a small telescope would be even better.”

Make Like a Tree and Leaf Less Energy Uncollected

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Young Naturalist Award — Aiden: The Secret of the Fibonacci Sequence in Trees

My investigation asked the question of whether there is a secret formula in tree design and whether the purpose of the spiral pattern is to collect sunlight better. After doing research, I put together test tools, experiments and design models to investigate how trees collect sunlight. At the end of my research project, I put the pieces of this natural puzzle together, and I discovered the answer. But the best part was that I discovered a new way to increase the efficiency of solar panels at collecting sunlight!
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The tree design takes up less room than flat-panel arrays and works in spots that don’t have a full southern view. It collects more sunlight in winter. Shade and bad weather like snow don’t hurt it because the panels are not flat. It even looks nicer because it looks like a tree. A design like this may work better in urban areas where space and direct sunlight can be hard to find.

Update: I missed that he was measuring the open-circuit voltage output, not current, for his arrays.

I Didn't Know Rainbows Were So Controversial

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They’re so very polarizing…

Polarized rainbow, what does this mean???

Rainbows are created when sunlight reflects inside water droplets, bouncing back to you. When the light enters the droplet and also when it leaves, it bends a little bit as well (like how a spoon looks bent in a glass of water). Different colors bend by different amounts, so the sunlight colors get spread out, forming an arc in the sky.
The light forming the rainbow gets polarized when it reflects off the back of the raindrop. The amount of polarization is pretty strong, as the video shows. When I hold the glasses horizontally the light gets through, but as soon as I rotate the glasses, the rainbow disappears entirely! Almost all the polarized light is blocked, and the rainbow vanishes.
But wait, there’s more!

This is the same effect that makes it easier to see through heavy rain or fog with polarized sunglasses.