physics

Twisted Language in Physics

Wednesday, June 22nd, 2011

From the discussion in Quantum Diaries, it seems that helicity is a property of motion and chirality a property of shape (where, in the case of an elementary particle, this might be represented by something like the shape of a level surface of its wave function).

The language chosen by physicists is unfortunate as a helix is an object with fixed chirality but the chirality of the path of a “helical” motion depends on the relative motion of the medium in which it is traced.

Christopher Norris Defends Philosophy

Sunday, February 20th, 2011

Christopher Norris has written an article in Philosophy Now defending the Philosophy of Science from allegations of its irrelevance by scientists (most recently Stephen Hawking for example).  Norris alleges the existence of "scientists’ need to philosophize and their proneness to philosophize badly or commit certain avoidable errors if they don’t take at least some passing interest in what philosophers have to say", and he asserts that modern theorists  "appear unworried – blithely unfazed, one is tempted to say – by the fact that their theories are incapable of proof or confirmation, or indeed of falsification..."  and further that "scientific theories – especially theories of the ultra-speculative kind that preoccupy theoretical physicists like Hawking – involve a great deal of covert philosophising which may or may not turn out to promote the interests of knowledge and truth". All of these claims might be considered plausible on the basis of attempts to "explain" quantum physics (and beyond) in popular literature, where analogies (which often really are used by physicists, but just to help guide their intuition) are often all that is provided.   It is true that some of these accounts can be faulted for not admitting that that is what they are doing, and perhaps that needs pointing out. But Norris seems to be doing the opposite by confusing the intuition-guiding analogies with the theories themselves.

Sunrise and Sunset at Solstices

Monday, January 3rd, 2011

It is curious that the days of shortest and longest periods of sunlight (which just about everyone knows are due to the tilt of the earth's spin axis relative to the plane of its orbit)  are not everywhere the same as those of latest and earliest sunrise. This is because the length of the full solar day is not actually constant and so the time of solar noon oscillates around the time that would correspond to noon on a steadily progressing clock.

This is often attributed to the eccentricity of the earth's orbit, and that does play a minor role. But actually, the effect is mainly due to another effect of the earth's tilt - a secondary effect on the difference between the length of a full solar day (taken by an apparent revolution of the sun from noon to noon) and a constant sidereal day (taken for a full revolution relative to the distant stars).

Miraculous Magnetic Clowns

Monday, November 29th, 2010

James McGirk, writing in 3quarksdaily, repeats the widely stated claim that the Insane Clown Posse display inexcusable ignorance when they claim, in their song 'Miracles', to be mystified by magnets.

One line in particular snagged the world’s attention: “Water, fire, air and dirt, Fucking magnets, how do they work?” Magnetism being a staple of primary school science education, the line struck many casual listeners as spectacularly ignorant.

The explanation of magnetism is definitely NOT a "staple of primary school science education" and the widespread disdain for that line in the song shows greater ignorance than the line itself.

In fact, when one commenter on the youTube site asserts that  "33,316 people know how magnets work scientifically" (which would be about five people in a million worldwide), that actually sounds about right.

I would venture to suggest also that, of those of us that do understand how magnets work, most consider it a miracle only slightly less astounding than the fact that we can actually understand it.

Back From the Future

Sunday, August 29th, 2010

An article in DISCOVER Magazine discusses an apparent influence of the decision to make later measurements on the results of earlier ones.

But then it turns out that the effect persists even when the later measurement is not recorded. Such cases are dismissed as experimental error, but perhaps it is just that the presence of the apparatus for the final measurement that causes the effect. Just as the half-silvered ends of a laser trap the photon between them, so perhaps do the apparati for initial and final measurement also trap the photon subjects of the Aharonov-Tollakson experiment.

Is there any significance in the fact that the article was originally printed in the April edition?

A Quantum Embarrassment to Scientific American

Saturday, March 14th, 2009

The latest Scientific American lead article Was Einstein Wrong?: A Quantum Threat to Special Relativity is an odd duck. It almost (but never quite) does a fair job of describing some quite challenging aspects of quantum mechanics and its relation to locality in special relativity, and yet manages to completely disgrace itself (and the magazine's editors) within its first paragraph by asserting that "radio waves propagate through the air" in an argument identifying the light-cone locality of special relativity with non-existence of action-at-a-distance.