Tuesday, May 31, 2005

Strongest Source of Gravitational Waves?

Stellar tango. These tightly orbiting white dwarfs, doomed to collide, churn space with gravitational waves in this artist's illustration.

At the American Astronomical Society meeting now under way in Minneapolis, Tod Strohmayer (NASA/Goddard Space Flight Center) reported on periodic X-ray pulsations from a source known as RX J0806.3+1527. The pulsations, found with the Chandra X-Ray Observatory, agree with earlier, visible-light observations indicating that the source is a pair of white-dwarf stars orbiting each other in a tight binary system. The two collapsed stars are separated by only 80,000 kilometers (50,000 miles, or one-fifth the Earth-Moon distance) and circle each other every 5.36 minutes. No known binary star has a shorter orbital period.

article in Sky and Telescope.

White Dwarfs in a Death Spiral in Science.

Female spiders exploit double-barrelled sperm storage

Redbacks use cannibalism and conniving to select the best mates.

Large female redbacks can collect sperm from more than one mate.
© Maydianne Andrade

Females seem to hold all the cards in this species.
Maydianne Andrade
University of Toronto, Canada

Female redback spiders are not the most sympathetic of lovers: they routinely begin to eat their suitors before they've had a chance to finish mating. And now research shows that their internal anatomy also helps them get one over males, by influencing which mates get to fertilize their eggs.

The female redback has two organs for storing sperm ...
The two sperm sacs help to prevent a male from stealing a mating advantage simply by being the first to court a female ... A male has two sperm-depositing organs, called palps, that correspond to the female's two sperm sacs, although he can use only one palp in a mating session.

A male tends to break off the end of his mating palp inside the female's sperm sac, partly blocking its entrance, the researchers say. "This functions as a plug, a kind of chastity belt," explains Paul Hillyard, curator of arachnids at the Natural History Museum in London.

Having two sperm sacs may therefore give females extra choice over who fathers her young ... If one of the sacs is blocked by a mate, a subsequent partner can still be given the opportunity to deposit his sperm in the other.

article in Nature News

Fertilizer from the stars

Could a gamma-ray burst have provided nutrients for early plants?
article in Nature by Philip Ball.

Twin beams of gamma rays are thought to burst from the supernovae of giant stars. Click here to see the animation.

The explosion of a star in our cosmic neighbourhood may not sound like good news for life on Earth. But a team of US researchers says that just such a catastrophe could have showered our planet with fertilizer that helped plants to colonize the land about 440 million years ago

a previous Gamma-ray burst post

Andromeda's Stellar Sprawl

Big surprise. . The classic starry disk of Andromeda (left, and central red section on right) extends far deeper into space than astronomers thought (yellow and green, right).
CREDIT: NOAO/AURA/NSF (left); R. Ibata et al./Isaac Newton Telescope (right)

The results are convincing but hard to understand, says astronomer Wallace Sargent of Caltech, who was not part of the study. "I find it very impressive, but I didn't expect to see ordered motion so far out," he says. Some unknown influence must settle the orbits and make them persist for billions of years, Sargent says.

article in Science Now

Galactic neighbour gets supersized in Nature News.

Bringing Up Baby a film by Howard Hawks

has finally come out on DVD. A classic screwball comedy starring Cary Grant and Katharine Hepburn and a great way to spend a rainy afternoon. Just to hear Hepburn pronounce the word "can't" is a delight.

Grant is an earnest paleontologist , Hepburn is his far from earnest nemesis. She loses his brontosaurus intercostal clavicle: audio clip

Quantum Weirdness: A Readers Guide

Einstein (and just about everyone else, for that matter) found some aspects of Quantum Mechanics profundly disturbing. Heisenberg's Uncertainty Principle and the probabilistic nature of quantum theory provoked him to the make the famous statement: "God Does Not Play Dice with the Universe". The EPR thought experiment of the 1930's (Einstein was the E), crystalized some of the strange elements of quantum mechanics, which almost (but not quite!) seems to violate relativity - (see however the post below).

Some of the strangeness of quantum mechanics was nicely isolated in Bell's Theorem, proposed in 1964 by John Bell, which seems to indicate there's a fundamental nonlocal nature to reality - according to quantum theory.

The simplest and most straightforward exposition of quantum weirdness I've found is in the article Quantum Mysteries for Anyone reprinted in "Boojums All the Way Through" by David Mermim.

can be downloaded as an ebook. Has a lot of quantum theory mixed in with very well-written biography by a physicist and long-time contributor to the New Yorker magazine.

For the more mathematically minded:

Quantum Theory, Concepts and Methods by Asher Peres, was the most helpful single reference for me.

The Feynman Lectures on Physics: Volume III is a classic.

Quantum Computation and Quantum Information
by Isaac L. Chuang, Michael A. Nielsen is a clear exposition of those topics.

Superluminal telecommunication: an observable contradiction between quantum entanglement and relativistic causality

Authors: Ruo Peng Wang

I present a schema for a superluminal telecommunication system based on polarization entangled photon pairs. Binary signals can be transmitted at superluminal speed in this system, if entangled photon pairs can really be produced. The existence of the polarization entangled photon pairs is in direct contradiction to the relativistic causality in this telecommunication system. This contradiction implies the impossibility of generating entangled photon pairs.

preprint in the physics archive

see also Quantum State of Entangled Photon Pairs by the same author.
I show that the photon pairs used in experimental tests of quantum non-locality based on Bell's theorem are not in the entangled quantum state. The correct quantum state of the ``entangled'' photon pairs is suggested. Two experiments for testing this quantum state are proposed.

The author expresses skepticism about quantum entanglement, which is the basis for many of the mind-boggling phenomenon of quantum mechanics. Unfortunately I don't have the background to evaluate his claims.

Quantum Physics from A to Z

Quantum Physics from A to Z in the Physics archive.

"This is a collection of statements gathered on the occasion of the Quantum Physics of Nature meeting in Vienna."

Since philosophers are beginning to discuss the “Zeilinger principle” of quantum physics [1, 2, 3] it appears timely to get a community view on what that might be. The interpretation in question seems to have been developed over a period totalling 60 years to the day and does not only concern quantum mechanics but physics as a whole.

One of the statements attributed to Zeilinger is "Good papers have to be sexy." This is apparently what passes for sexy in the world of quantum information theory.

A Quantum Constraint for the Physical Viability of Classical Traversable Lorentzian Wormholes

Authors: Kamal K. Nandi, Yuan-Zhong Zhang, Nail G. Migranov

The physical viability of classical wormholes can be ascertained by computing if the total volume of exotic matter needed to maintain the wormhole is finite. Using this value as the lower bound to the quantum ANEC integral, we confirm that only Planck size wormholes can be supported by the massless quantum Klein-Gordon field. Some known wormholes seem to be physically unrealistic.

preprint in the physics archive

The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. This is the ‘quantum of length’, the smallest measurement of length with any meaning.

And roughly equal to 1.6 x 10 to the -35 meters or about 10 to the minus 20 times the size of a proton.

Pretty useless, and that's all this paper wants us to have.
This is more like it!

Can't we please have our wormholes?

Volcano of Colima Erupts in Mexico

Smoke and ash from the Colima volcano, on May 25 2005, 430 miles northwest of Mexico City, in what was the largest eruption in 14 years. (Photo: AP)

October 2004 from Volcano of Colima Mexico, photos

Photograph courtesy of Abel Cortes, Colima Volcano Observatory,
University of Colima, November 22, 1998.
Aerial view of Colima Volcano moments after a lava flow on the upper flank of the volcano collapsed; the photograph is tilted slightly (horizon is in upper right). The white plume is rising directly from the summit of the volcano. The tan-colored ash cloud on the volcano's flank (left side in this view) is rising from a pyroclastic flow. The fast-moving pyroclastic flow was caused by the collapse of a thick lava flow that was extruding from the summit area and oozing down the volcano's steep upper cone. When the lava flow collapsed, the hot lava broke apart into fragments ranging in size from boulders to tiny ash particles and swept down the volcano under the influence of gravity to form the pyroclastic flow; the flow reached a maximum distance of 4.5 km from the summit.

More images and information on Colima at Volcano World (Colima)

SI / USGS Weekly Volcanic Activity Report

A Romantic Love Poster

This poster explains Romantic Love (sorry all you poets)

Article in the New York Times: Watching New Love as It Sears the Brain

co-author Helen Fischer
her web site

Casablanca has been called the most romantic film ever ...
but that was before brain scans.

Spitzer Captures Fruits of Massive Stars' Labors

Check out the Spitzer Space Telescope website at Caltech for more information and spectacular images of the massive star Eta Carinae and the surrounding nebula at Spitzer Captures Fruits of Massive Stars' Labors.

For background information on Eta Carinae try this link

Two of my favorite books about stars are both by James B. Kaler,
The Hundred Greatest Stars and Extreme Stars, both of which discuss Eta Carinae.