Monthly Archives: June 2010

Drinking My Vodka and Lime

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Uncertain Principles: Relativity on a Human Scale

Precision clock measurements from NIST, directly observing both gravitational and kinematic time dilation, all without leaving the lab.

You can do this type of experiment with less precise devices, but you’d have to have a more robust apparatus to accumulate the data because you’d need to do a longer experiment. I’ve detailed how commercially available clocks have done the kinematic dilation measurement, though at ~30 m/s rather than 10 m/s, which required an experiment lasting several days. Similarly, one could do an experiment with clocks on different floors of a building over the course of a few weeks and see a gravitational redshift. It’s probably not worth the effort to go out of your way to do so, given the level of confirmation we already have for relativity — GPS works, for example.

The trick here is that these measurements were made in a relatively short period of time, but that’s generally the nature of cutting-edge science like this — it takes a lot of effort to get all the parts to run, and the experiment yields data for a limited time. So Chad is correct in asking whether they really count as “official clocks” — they don’t insofar as timekeeping is concerned. They probably don’t run long enough to really impact a true clock ensemble. The value here is that what’s hard to do today will be easier to do tomorrow, and eventually this (or a competing) kind of technology will become “true” clocks that are more compact and run continuously for extended periods and do have a significant impact on timekeeping.

(I should be listening to similarly-themed talks this week — I was supposed to go the Frequency Control Symposium. But I managed to get sick — not vodka-induced, BTW — as the weekend drew to a close. No way I was getting on a plane at that point. Bleh.)

If it Disagrees with Experiment, it's Wrong

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Feynman sums up science

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What he doesn’t explain here, however, is that there are varying degrees of wrong. Some kinds of wrong mean you abandon the theory. Other kinds of wrong mean you adjust the theory. Once can look at the scrap heap of discarded theories for examples of the former — phlogiston, for example, predicted that mass had to decrease in the process of combustion, because it was a substance released during the process. After that was shown to be wrong, the theory was discarded. There was no way to fix the problems, since it wasn’t a matter of refinement.

An example of refining a theory is found in laser cooling. When it was first proposed, the mechanism was Doppler cooling, stemming from a simple model of photon recoil in a two-level system, and was experimentally confirmed. But eventually experimenters discovered conditions where their laser-cooled atoms were colder than the Doppler limit. Atoms are not two-level systems, and there are conditions in which their structure can be exploited to cool the atoms further: polarization gradients in the laser light, giving rise to “Sisyphus” cooling, in which the energy levels of the atoms are shifted depending on their position, and it is possible to have some atoms continuing to lose energy as they scatter photons, somewhat like the mythological Sisyphus, who was cursed to continually push a rock uphill. It was this discovery and explanation that won the 1997 Nobel prize for Bill Phillips, Steven Chu and Claude Cohen-Tannoudji.

There are more of these examples, with the hallmark being that the original theory is seen to no longer have universal applicability, but is still used under the conditions in which it applies. Relativity comes immediately to mind; we still use Newton’s law of gravitation, still use the classical equations for e.g. kinetic energy and do Galilean transforms when using them doesn’t introduce appreciable error.

Is it Cromulent?

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One-day wonder

A couple of weeks ago, an apparently totally made-up new word seemed to set the land-speed record for the jump from “early use” to “inclusion in a dictionary.” On May 12, the word malamanteau showed up in the Web comic xkcd, where it was defined as “a neologism for a portmanteau created by incorrectly combining a malapropism with a neologism.”

It’s not the clearest definition ever written, but the idea is that a malamanteau blends one or more not-quite-right words to create a completely new one. Examples include the classic misunderestimated, bewilderness (as in “lost in the bewilderness”), and insinuendos (innuendo + insinuation)

I think the author missed an opportunity by not asking the titular question.

xkcd: Malamanteau

We're All Idiots, or Worse

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Over at Physics and Physicists, I saw the post entitled Graduation Speaker Perpetuates Myth, in which the old “science says bumblebees can’t fly” canard is reported, yet again. What gets me is about such stores is the willingness to accept that scientists are imbeciles — embracing the idea that we would advance models as truth, despite the fact that they are so trivially falsified. In science, if the theory does not match the experiment, you know something is wrong with the theory, so you change the theory. (in this case, a combination of the assumption about the rigidity of the wing and the nascent state of aerodynamic modeling limited a back-of-the-envelope calculation at a dinner party)

Worse, in addition to (or perhaps a subset of) the willfully ignorant, we have the conspiracy theorists. Not only is the science wrong, but we’re all actively covering up the flaws. Never mind that if any technology based on the science actually works, it’s a bit troublesome for their position. My favorite is the anti-relativity crowd scrambling to explain how GPS actually can work.

In light of that, it was interesting to read about what has been termed scientific impotence: When science clashes with beliefs? Make science impotent

What Munro examines here is an alternative approach: the decision that, regardless of the methodological details, a topic is just not accessible to scientific analysis. This approach also has a prominent place among those who disregard scientific information, ranging from the very narrow—people who argue that the climate is simply too complicated to understand—to the extremely broad, such as those among the creationist movement who argue that the only valid science takes place in the controlled environs of a lab, and thereby dismiss not only evolution, but geology, astronomy, etc.

So now we have the addition of science isn’t equipped to answer that question.