Category Archives: Physics

Thermodynamics is a Good Idea

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Toyota has a new commercial series out, going by the moniker “Ideas for Good.” The gist of it is using technology that they have invented, or at least use, and point it to new applications. The first one I saw was crash modeling and using it to analyze football collisions to help reduce concussions. Great.

But the next one was taking regenerative braking and putting it on roller coasters, so that we could “create the world’s first self-sustaining amusement park.” Which sounds suspiciously like perpetual motion. You can’t do it. You will always have losses of your useful energy (heat), and can’t recover all of the mechanical energy to use it again. Maybe they meant something else, but if they did, the execution was off.

Here is a link to the commercial, in case you want to watch it.

Visualizing Your Microwave Oven

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I don’t have a microwave oven, but I do have this big clock that can cook things.

You need to a flashplayer enabled browser to view this YouTube video

The guy who did the video has a blog, and from that I’m a little surprised at some of the commentary in the video.

The absorption by the “salty water” isn’t correct — water isn’t absorbing the microwaves because it’s salty; it’s a polar molecule and will respond to the oscillating electric field all by itself. Ions would do this too, so having a dissolved salt probably doesn’t hurt or even helps, but distilled water will absorb microwaves and heat up. This is immediately followed by “turns the microwaves into heat,” which treats heat like a substance. The water is heated, but does not contain heat.

You also can’t see steam coming out of the glass, because you can’t see steam — it’s the vapor phase of water, and is not visible. What you can see are small water droplets, after the vapor has begun to coalesce. Yeah, I know that steam is used colloquially like this, but I expect better of a scientist.

Trapped Like Anti-Rats

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Uncertain Principle: Trapped Antihydrogen

What’s the point of making antimatter if you can’t use it to blow stuff up? The point is to understand the laws of physics better. If you can do spectroscopy of anti-atoms, it will tell us a lot about whether antimatter obeys the same laws as ordinary matter, which might provide a clue as to why everything we see seems to be made of ordinary matter. You could also use it to test how antimatter interacts with gravity, which is something we don’t currently have any way to test.

Not Talking About Ice IX

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American Drink: Ice Part 2: How to Make the Best F***ing Ice Ever

3. Boil the water

Totally optional in my opinion. If you want super clear ice, boil it to get rid of trapped gasses. I don’t bother much. I’ve already impressed myself just by getting out of bed in the morning and getting out of my jammies. j/k I’m still in my jammies. If you happen to boil water for French Press coffee in the morning, boil extra but don’t go out of your way for it and again, filtered tap water is just fine.

A particular ice tray is recommend in the post, and I had seen it before, but it (and other new silicone ice trays I’ve seen) suffer from one major flaw: there is no “cheater” slot connecting adjacent cube spaces, which would allow water to move between them and even the levels. This makes it hard to fill with water that’s not straight out of the tap, without spilling; one hand is occupied by pouring, and for most of us that leaves only one hand to hold the tray (if you aren’t named Zaphod Beeblebrox). I’m not sure if this is a design oversight, or a structural limitation imposed by using silicone.

Demonic Journalists Turn Truth Into Fiction

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(Apologies if this is overly rant-y. I’ve been suffering though a discussion from a creationist that boils down to “information” can’t increase, therefore evolution is impossible. I’m therefore a little sensitive to the topic of information and thermodynamics)

Demonic device converts information to energy

The laws of physics say that you can’t get energy for nothing — worse still, you will always get out of a system less energy than you put in. But a nanoscale experiment inspired by a nineteenth-century paradox that seemed to break those laws now shows that you can generate energy from information.

Of course, the key word is seemed. This is my main peeve here. The all-to-common insinuation that some law of nature has been violated.

Of course, later on (not paragraph 19, though), they admit

The experiment does not actually violate the second law of thermodynamics, because in the system as a whole, energy must be consumed by the equipment — and the experimenters — to monitor the bead and switch the voltage as needed. But it does show that information can be used as a medium to transfer energy, says Sano. The bead is driven as a mini-rotor, with a information-to-energy conversion efficiency of 28%.

I’m not sure how they get to “information is a medium to transfer energy,” and from that to “information is converted to energy.”

There’s a somewhat better article, via Dr. SkySkull

[T]here is energy in information. To store a bit of information a system like a computer memory needs to be put into a defined state, either a ’1′ or a ’0′.

That seems more reasonable — storing information (and all information needs to be stored) requires energy, so there is energy in information storage. But what is being presented as “information” is just the state of a system; one could just as easily say there is energy in e.g. an electron’s orientation in a magnetic field (or the location of a polystyrene bead, as in this case), and skip the discussion about information.

It sounds like a version of the Brownian ratchet, where a paddle would spin in only one direction from random collisions, because the ratchet would impede motion in the other direction. It fails because the ratchet, too, would be subject to collisions, and fail to work if everything were at the same temperature. Here, the mechanical ratchet has been replaced by an electric field, which is not in thermal equilibrium. You expend energy determining when to change the field.

I’m glad I didn’t run into any stories that called it “pure energy.” Oh, crud.

Edit (11/22) Sean does a summary, which makes a lot more sense.

The connection is not that “information carries energy”; if I tell you some information about gas particles in a box, that doesn’t change their total energy. But it does help you extract that energy.

Oh, Say, Can You See This?

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How Do You See Interference Between Independent Lasers?

[T]his is traditionally done with a single laser and two slits. In principle, you ought to be able to do it with two completely independent lasers of the same wavelength, and see an interference pattern that way. In practice, though, this is very hard to do, as the phase difference between two independent lasers will jump around randomly at a very high rate. At any given instant, the two lasers will interfere with each other to make a nice double-slit pattern, but the positions of the bright and dark spots will shift around randomly, so fast that your eye can’t follow them.

Clang II: The Wrath of Oersted

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When last we left our intrepid physicists, they (meaning we) had, after many trials and tribulations, found a magnetic washer that was messin’ with our clock. We removed it, killed it and had it stuffed and mounted on the wall. A couple of you posted congratulatory notes on the success of the mission. I had delayed posting the story until we had confirmed that the vacuum was intact, because Murphy has a way of penalizing premature celebration. And the vacuum was fine the next day. Nope, no problems with the vacuum.

But I still should have waited. The problem is that there was still an icky nasty foreign magnetic field. At first we thought that maybe we (meaning I) had screwed up the shields by getting a magnet too close. And by too close, I mean I accidentally waved my hand too close to one part and heard a resounding THUNK! as the magnetic attraction (however the funk that works) overwhelmed my grip. We routinely degauss the shields, but there’s always the spectre of “burning” in a strong enough localized field that the degauss-o-tron can’t handle. That made for a bit of stomach acid on my part until we confirmed that the shields were fine. The problem was localized to the location of another bolt.

Yikes.

But it wasn’t just a washer this time. There was another one, even though we had asked the magic eight-ball if the problem was fixed and we got a “Signs point to YES” answer. At this point we were incredibly paranoid and with good reason — the pathology was far more sinister. We had noticed that some of the titanium bolts we used would have titanium chips inside the socket head, from the broaching process used to create the hexagonal shape. But they’re titanium chips, right? It’s only a problem if they keep you from tightening the bolt. Or so we had thought, and while we did clean the bolts up, we weren’t as anal meticulous as we needed to be: the problem (most likely one, at least) is that the tool itself is steel, and tools will occasionally chip. And that chip can get caught in with the broaching chips, lodged inside the cap-screw, and that, my friends, is pure evil.

So we scraped and tested — I did my best Nick Stokes impersonation and gathered the specks on some tape so I could wave it in front of the detector, and pretty soon we found one that buried the needle (metaphorically, at least; it was a digital meter)

That’s the one who slimed me. The ugly little spud above the 5″ line. (Yes, we have English-system rulers in the lab. They are a nanosecond long.)

Everything seems to be fine now. This time I waited until I could check that things were running well, and confirm we’re moving on to tackling the next gremlin in the lab.

Thinking in a Different Corner of the Box

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I often despise the phrase “think outside the box” because when I see it on the scienceforums.net boards, it’s usually proffered by a crackpot who is using it to mean “Pay no attention to the violation of the first or second law of thermodynamics behind the curtain.” In that sense, the box is physics, and everything is inside the box. You might find the box is a slightly different shape, or there is something interesting in the corner, but everything is inside the box.

Here’s a story from an older article. The thinking was inspired.

Open minds reap rewards

The year before, in 1952, Ed Salpeter, a researcher in New York, had pointed out that the beryllium barrier might be leapfrogged if, in the heart of “red giant stars”, three helium nuclei collided almost simultaneously, gluing together to make carbon-12. It was the nuclear physics equivalent of three shopping trolleys colliding simultaneously in a car park. Unfortunately, this process was fantastically unlikely.

Enter Hoyle. His argument, as as far as Fowler could make out, was that the process would be speeded up if, by a bizarre coincidence, carbon-12 had an energy state exactly equal to the energy of three colliding helium nuclei at the 100 million-degree temperature inside a red giant. That energy was 7.65 MeV. The state had to exist, reasoned Hoyle, because life existed and life was based on carbon.

Scientific thought like this gives me a hadron.