Thursday, May 26, 2011

Electron Dipole Moment Small

[W]e use cold polar molecules to measure the electron EDM at the highest level of precision reported so far, providing a constraint on any possible new interactions. We obtain de = (−2.4±5.7stat±1.5syst)×10−28ecm, where e is the charge on the electron, which sets a new upper limit of |de|<10.5×10−28ecm with 90 per cent confidence. This result, consistent with zero, indicates that the electron is spherical at this improved level of precision.

From Nature.

The Standard Model predicts a small electron dipole moment, as a consequence of the small charge parity violating phase in the CKM matrix, but that is far too small to be revealed in this experiment and most beyond the Standard Model theories predict a larger than Standard Model electron dipole moment.  Another factor of a hundred in precision, if it also reveals a result consistent with zero, would rule out many "beyond the standard model" theories of physics.  As it is, the new result, which is 1.5 times smaller than the previous standard set in 2002, merely tightens the constraints on theorists a bit more  than past results and confirm the general finding of past research that the electron dipole moment is very small.

What Moods Are Most Attractive?

Women really are more beautiful when they smile. But women prefer body language that is emo or screams power to contentment.

["M]en and women respond very differently to displays of emotion, including smiles."

In a series of studies, more than 1,000 adult participants rated the sexual attractiveness of hundreds of images of the opposite sex engaged in universal displays of happiness (broad smiles), pride (raised heads, puffed-up chests) and shame (lowered heads, averted eyes).

The study found that women were least attracted to smiling, happy men, preferring those who looked proud and powerful or moody and ashamed. In contrast, male participants were most sexually attracted to women who looked happy, and least attracted to women who appeared proud and confident.

From here citing Jessica L. Tracy, Alec T. Beall. Happy guys finish last: The impact of emotion expressions on sexual attraction. Emotion, 2011; DOI: 10.1037/a0022902.

Perhaps this says something about the psychological bargain we are looking for, on average, when we seek a partner in the dating game. If women are selling happiness, someone who is already content is unlikely to want what they offer. If men are seeking to exchange their success for happiness from a woman, a woman who already have circumstances that make her feel proud and powerful is less likely to be interested in making that exchange.

The second place attraction of a shamed woman in this hierarchy to men also makes sense in this model. She too is looking for the success that a man can offer and if she may not be offering happiness she may at least be offering loyalty. Similarly, an emo man may be the most responsive to the happiness that a happy woman can offer, because he lacks that joy, again also fostering loyalty.

It would have been interesting to know if the results were homogeneous. Do all woman and all men have the same hierarchy of preferences? Or, are there different subtypes of people who have different priorities?

One can imagine, for example, an independently wealthy woman or one with a successful career having different priorities in men than a woman who is hoping to spend time as a dependent mother of here mate's children. Put another way, maybe cougars have different priorities than debutantes that are reflected in what they find to be attractive in terms of emotional displays.  I suppose it will take more studies to establish that.

Monday, May 23, 2011

More Evidence For Weirdness In Weak Gravitational Fields

The single most interesting feature of attempts to replace dark matter with a modification of gravity is Milgrom’s discovery that in a wide variety of galaxies, there’s a unique place where ordinary gravity plus ordinary matter stops working: when the acceleration due to gravity (as Newton would have calculated it) drops below a fixed value a0 ≈ 10^−10 m/s2. This is the basis of MOND, but the pattern itself is arguably more interesting than any current attempt to account for it. . . but in any event it should be explained somehow.

From here

A clever new test of gravitational weak fields finds the same effect in a pre-print whose abstract appears below:

The Breakdown of Classical Gravity? X. Hernandez, M. A. Jimenez, C. Allen

Assuming Newton’s gravity and GR to be valid at all scales, leads to the dark matter hypothesis as a forced requirement demanded by the observed dynamics and measured baryonic content at galactic and extra galactic scales. Alternatively, one can propose a contrasting scenario where gravity exhibits a change of regime at acceleration scales less than $a_{0}$, and obtain just as good a fit to observations across astrophysical scales. A critical experiment in this debate is offered by wide orbit binary stars. Since for $1 M_{\odot}$ systems the acceleration drops below $a_{0}$ at scales of around 7000 AU, an statistical survey of relative velocities and binary separations reaching beyond $10^{4}$ AU should yield a conclusive answer to the above debate. By performing such a study we show Kepler’s third law to fail precisely beyond $a \approx a_{0}$ scales, precisely as predicted by modified gravity theories designed not to require any dark matter at galactic scales and beyond.

From a sociology of science perspective, it is particularly notable that this empirical data point is (1) predicted by a decades old theory, (2) found at a time when the Bullet Cluster example strongly disfavors a MOND mechanism, and (3) looks at a very different type of physical system than the one that formed a basis for the original theory.

To echo Sean in the first blockquote, the really important point is that the MOND cutoff is a simple, consistent cutoff that appears in a wide variety of circumstances and has repeatedly predicted new discoveries before empirical evidence was in place to test those predictions. Whatever its cause, the empirical phenomena is real and any theory of dark matter or quantum gravity that is consistent with empirical data has to reproduce this effect over a wide range of phenomena.

UPDATE: Motl plays with a variant on the MOND/TeVeS line of reasoning for modified gravity to produce a similar effect that is derived from the wave-like character of matter, the speed of light, the size of the universe and the holographic principle, that he called "HOND."

One interesting nuance of his idea is that in cosmology, the modified gravity effect would change as the universe gets bigger. The effect would have been stronger in the early universe than it is now.

UPDATE May 24, 2011: See also X-ray observaton evidence for low density, high temperature filaments that are part of the large scale structure of the universe.

Sunday, May 22, 2011

Turtle Island

The Iroquois people of the Northeast Woodlands say our land began when "Muskrat" placed a speck of earth on "Turtle's" back - hence the Indian name for America, "Turtle Island."

From the program notes to "Ballads of Turtle Island" by Jack Fredericksen, first performed by the Colorado Wind Ensemble on May 21, 2011 in Littleton, Colorado.

This blog is a companion blog to Wash Park Prophet. It discusses politics, law, Denver and all things intertwined inextricably with them. It is very much a blog that is about what is happening in the moment.

Dispatches from Turtle Island strips away the names on the political map and goes back to the oldest name for this place that I know, "Turtle Island." It is devoted to science, history, pre-history and musings on life and the human condition that go beyond politics, that have nothing to do with the law, and that are not particular to the neighborhood and city where I live. Rather than focusing on current events, this blog takes the longer view.

The hope is that each blog will have more focus and a clearer voice. In time, they will each have contrasting layouts. I plan to post to each blog regularly, but to post less to both blogs combined than the sixty posts a month pace that I've been keeping up at Wash Park Prophet. We'll see how it works out.

Thanks for reading.