Category Archives: Physics

MIT Tea

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No joke: This is the biggest battery breakthrough ever

The key to this new technology is that the metals that would normally be solids in a conventional battery have been broken into nano-size particles that are suspended in a liquid. The batteries, known as “semi-solid flow cells,” store their power in a black gunk that looks like motor oil, which has earned it the nickname “Cambridge Crude.” Because charge is stored in this liquid, it would be possible to “fuel up” an electric car with charged liquid electrolyte, just like fueling up at a conventional gas pump.

That’s pretty neat.

Shrinking Bob's Head

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I posted a pendulum video a while back, right about the same time another movie was getting some exposure, and the latter has gotten a lot of attention on the blogohedron because it’s like, all professionally done, if you like that sort of thing. And my pocket-camera-video tryingtodoitallonmyownwithoutatripod effort came up a bit short (by a factor of about 20,000 so far)

Anyway, I see that some math has appeared: Wave Pendulum Analysis

A Headline Query Whose Answer Might Be "Yes"

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Could Liquid Nitrogen Help Build Tasty Burgers?

“The freezing followed by the burst of high heat lets you brown the outside without overcooking the inside,” Dr. Myhrvold said. And the deep-frying is supposed to be a technological improvement over the classic White Castle spatula-on-a-griddle technique.

“On a griddle,” he explained, “even when you press a burger with a spatula, you can’t make all of it contact the surface because the edge of the burger is crenellated, with all these nooks and crannies formed by the cylinders of raw meat. But if you put it in hot fat, that fat penetrates and you get a super-thin layer of crispy Maillard browning all the way around those meat fibers.”

Coordinate Transformation, Tommy Roe Edition

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it’s you girl makin’ it spin, you’re making me dizzy

Go-Pro Camera on a Hula-Hoop. Gotta get me one of these cameras.

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DIY Electronic Curmudgeonry

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HOWTO make a Joule Thief and get all the power you’ve paid for

This wee beastie is a Joule Thief, a device whose sole purpose in life is to exhaust the power remaining in batteries that are too weak to do anything else. Simply build these and affix them to your “dead” batteries and thrill to the spectacle of the power you’ve paid for being available to you, right down to the last dribble.

Then go out on the porch, shake your fist, and tell those damn electrons to get off your lawn. If you want to skip the curmudgeonly comment, you can go straight to the instructable.

(I use rechargeables, so I have no need of an electron-marrow-sucking device)

Why They Bothered

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Finally, results from Gravity Probe B

There has been a bit of discussion on theses results already, but I note this one because I liked the summary about why the experiment was done:

Even though it is popular lore that Einstein was right (I even wrote a book on the subject), no such book is ever completely closed in science. As we have seen with the 1998 discovery that the universe is accelerating, measuring an effect contrary to established dogma can open the door to a whole new world of understanding, as well as of mystery. The precession of a gyroscope in the gravitation field of a rotating body had never been measured before GP-B. While the results support Einstein, this didn’t have to be the case. Physicists will never cease testing their basic theories, out of curiosity that new physics could exist beyond the “accepted” picture.

My only nit is that if we are testing the models, they are not dogma. There’s a subspecies of crackpot that rails against science as a religion who appear to miss the whole “experimental confirmation” aspect to science. They paint a picture of scientists who blindly, unquestioningly accept Einstein and it just isn’t the case.

Looking for a Straw-Colored Needle in a Large Haystack

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There’s a bit of buzz about the WHO characterizing cell phones as “possibly carcinogenic to humans”. This is a pretty detailed explanation of what that means, from Ed Yong (I think; the link that brought me here said so, but I don’t see Ed’s name on the page anywhere)

World Health Organisation verdict on mobile phones and cancer

What does that mean?
It means that there is some evidence linking mobile phones to cancer, but it is too weak to make any strong conclusions. Specifically, IARC’s panel said that the evidence that mobile phones pose a health risk was “limited” for two types of brain tumours – glioma and acoustic neuroma – and “inadequate” when it comes to other types of cancer.

The Chairman of the group, Dr Jonathan Samet, said, “The conclusion means that there could be some risk, and therefore we need to keep a close watch for a link between cell phones and cancer risk.”

The post goes into some detail about why this is really a non-issue: there is still no proposed mechanism, there are obvious flaws in some of the studies and there are a lot of conflicting results. That last part ties into an important point — the underlying reason that researchers are getting conflicting results is because the system being measured is inherently noisy and the effect under scrutiny is small.

The increased risk‚ from one of the studies (remember, there are others that saw no increased risk), is a 40% increase of those two types of brain tumors, which sounds like a lot, except … you need to look at this in context. Even a substantial increase in a small risk still leaves you with a small risk. We’ve seen this before with traffic analysis, and now we have it for cancer analysis. Matthew Herper has already run the numbers

96% of the U.S. population, or about 300 million people, have cellphones. If everyone’s risk of glioma went up 40% as a result of cellphone use, the number of gliomas in the U.S. would increase by 8,000. That’s a one in 40,000 increase in each person’s risk of glioma, which still isn’t very big.

But the study the WHO is citing only showed the 40% increase in the 10% of people who used cellphones most. I don’t know how many people in the U.S. would now fall into this group, but we’d be talking about maybe hundreds of cases spread out over the whole U.S. population.

We can look at this another way. A fair amount of data has not yielded a statistically significant result. Any signal that exists is still buried in the noise, requiring more statistics, but until you get those statistics, you can’t rule out an effect. What you can do is say that the effect is no larger than some amount, and what is probably the worst-case scenario analyzed above — in the unlikely event the study wasn’t an aberration — yields a very small risk. Which is probably why the collective response of scientists has been “meh”

Great Balls o' Leidenfrost!

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Hot bodies have less drag

[R]esearchers have shown the Leidenfrost effect works very well in reverse. They dropped metal balls heated to different temperatures into a liquid and watched how fast they fell. The chose a room temperature ball, a heated ball that wasn’t enough to make the Leidenfrost effect occur, and a ball heated above the Leidenfrost temperature.

Moving through water vapor is easier than through liquid. There should be some speed where you can’t boil the water quickly enough, though, and you get a transition of the effect in the right-hand tube to that of the middle tube, or something similar.

h/t to @JenLucPiquant

Remember Mpebma

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One of the easily-forgotton tenets of science, or perhaps a commandment: Remember thy assumptions, for they may fail to hold.

Mpemba’s baffling discovery: can hot water freeze before cold? (1969)

[W]e see an admirable open-mindedness of Professor Osborne in his dealings with Mpemba, and that open-mindedness would quickly benefit them both. Conversely, we see a dangerous “groupthink” amongst Mpemba’s classmates regarding science, in which they are genuinely offended by Mpemba questioning the status quo. Mpemba shows great wisdom in his answer: “Theory differs from practical”. This is an important point for anyone studying physics: we like to create simplified models to explain nature, but those models often lose real-world aspects in the process of stripping them down.