Who Ordered That?

Top Quark turns 15 today

Tue, 02 Mar 2010 21:46:10 +0100

Happy birthday, Top Quark!

"Elegance is for the tailor and the shoemaker."

Sun, 28 Feb 2010 20:37:40 +0100

“Elegance is for the tailor and the shoemaker.”

- Ludwig Boltzmann, a pragmatic mathematician and theorist. Via Boltzmann’s Atom: The Great Debate That Launched a Revolution in Physics by David Lindley, Free Press, 2001.

"Music is the pleasure the human mind experiences from counting without being aware that it is..."

Sat, 27 Feb 2010 21:01:27 +0100

“Music is the pleasure the human mind experiences from counting without being aware that it is counting.”

- Gottfried Wilhelm von Leibniz

Royal Society Michael Faraday Prize Lecture 2010

Fri, 26 Feb 2010 18:44:58 +0100

Royal Society Michael Faraday Prize Lecture 2010:

Marcus Du Sautoy, Simonyi Professor For The Public Understanding of Science at Oxford, gives the 2010 Michael Faraday Prize Lecture at the Royal Society.

In the talk, titled The Secret Mathematician, Du Sautoy debunks the ‘arts versus sciences’ dichotomy with heaps of examples of mathematics being used directly in the arts — in music by Messiaen and Schoenberg, in the architecture of Palladio and Le Corbusier, in the writing of Borges, and in the art of Dali and Picasso.

Artists are constantly on the hunt for interesting new structures to frame their creative process. From composers to painters, writers to choreographers, the mathematician’s palette of shapes, patterns and numbers has proved a powerful inspiration.

I never considered L’Arche at La Defence, as being a shadow of a 4D hypercube, but I’ll appreciate it even more next time I’m in Paris.

Early Galaxies Formed Stars Fast Because They Had More Gas | Wired Science | Wired.com

Sat, 13 Feb 2010 17:39:12 +0100

Early Galaxies Formed Stars Fast Because They Had More Gas | Wired Science | Wired.com:

Wired Science explains results showing that early galaxies had more hydrogen to fuel star-formation:

Ultimately, the team wanted to know how much hydrogen filled these early galaxies, because it is by far the most abundant element in the universe and in interstellar gas clouds. But hydrogen emissions from these distant objects are simply too hard to detect, Tacconi said.

Instead, they measured the light emitted from carbon monoxide molecules. As these molecules rotate, they shift from one energy state to another. As they shift, “they emit photons, and that radiation is what we see as an emission line at a specific wavelength,” Tacconi said.

The amount of light emitted from these spinning molecules revealed the fraction of each galaxy made up of carbon monoxide. Carbon monoxide and hydrogen are found in almost the same ratio in many parts of the universe. So, they used this ratio to extrapolate the amount of hydrogen present in these early galaxies.

Helium clue found in echo of the big bang - space - 08 February 2010 - New Scientist

Wed, 10 Feb 2010 23:58:30 +0100

Helium clue found in echo of the big bang - space - 08 February 2010 - New Scientist:

New Scientist reports on a combination of results from telescopes including the Wilkinson Microwave Anisotropy Probe:

A trio of telescopes has found helium’s signature in the cosmic microwave background, radiation emitted some 380,000 years after the big bang. The patterns in this radiation are an important indicator of the processes at work at that time. Helium affects the pattern because it is heavier than hydrogen and so alters the way pressure waves must have travelled through the young cosmos. But helium’s effect on the CMB was on a scale too small to resolve until now.

The biomechanics of barefoot running : Nature

Sun, 07 Feb 2010 22:10:19 +0100

The biomechanics of barefoot running : Nature:

A paper in Nature on the mechanics of human running. In the study, runners tended to land on the ball of the foot or flat when barefoot but on the heel—with a greater impact— when shod in modern running shoes.

A comparison by Daniel Lieberman and colleagues of the biomechanics of habitually shod versus habitually barefoot runners now suggests that the collision-free way that barefoot runners typically land is not only comfortable but may also help avoid some impact-related repetitive stress injuries. Kinematic and kinetic analyses show that modern shoes allow runners to land on the heel, as they do when they walk. Runners who don’t wear shoes land more often on the ball of the foot or with a flat foot.

Technology Review: Blogs: arXiv blog: How to Build a Dark Energy Detector

Thu, 04 Feb 2010 16:31:58 +0100

Technology Review: Blogs: arXiv blog: How to Build a Dark Energy Detector:

The arXiv blog on a suggested experiment for detecting dark energy:

Of course there are some important differences between an electric field and the dark energy field that make measurements tricky. Not least of these is that you can’t turn off dark energy. Another is that there is no known reference against which to measure it.

That leaves the possibility of a gradient in the dark energy field. If there is such a gradient, then it ought to be possible to measure its effect and the best way to do this is with atom interferometry, say Perl and Mueller.

"It all works because Avogadro’s number is closer to infinity than to ten."

Sun, 31 Jan 2010 21:40:27 +0100

“It all works because Avogadro’s number is closer to infinity than to ten.”

- Ralph Baierlein, American Journal of Physics 46, 1045 (1978).

Giant laser reaches key milestone for fusion - physics-math - 28 January 2010 - New Scientist

Fri, 29 Jan 2010 21:54:34 +0100

Giant laser reaches key milestone for fusion - physics-math - 28 January 2010 - New Scientist:

New Scientist reports on progress at Lawrence Livermore National Laboratory, using the world’s largest laser to compress a spherical pellet in order to ignite a fusion reaction:

The team used targets that did not contain the key ingredients for fusion – two isotopes of hydrogen known as deuterium and tritium. But the symmetrical implosion of the targets suggests that NIF should be able to ignite fusion with laser pulses of 1.2 to 1.3 megajoules – well below its full 1.8-megajoule capacity.

Researchers spent last year slowly cranking up the output of the laser, ultimately reaching a total energy of more than 1 megajoules. Now they’re pausing to mount new instruments on the 10-centimetre-thick aluminium target chamber and to install giant concrete doors to contain neutrons they expect to produce in future fusion experiments.

Single-Photon Cooling: Making Maxwell's Demon

Thu, 28 Jan 2010 21:58:05 +0100

Single-Photon Cooling: Making Maxwell's Demon:

Chad Orzel at Uncertain Principles explains an experiment from a group at Texas, putting Maxwell’s Demon to work:

The key to their scheme is the position of the “demon,” which is right along the outer edge of the trap. The only atoms that get far enough out to encounter the demon are necessarily very close to their turning point, and thus moving very slowly. When they drop into the laser trap, they have almost no kinetic energy, and thus a very low temperature. This is exactly the cooling effect you get with Maxwell’s demon.

The experiment described in the paper is basically a proof-of-principle demonstration of the technique. They only loaded a small fraction of the atoms into their laser trap (their highest claimed efficiency was about 2%), and only really cooled the atoms in one dimension. Still, they were able to select out a sample of a few hundred thousand atoms at 4.3μK, starting with a sample at 53μK. This also increased the “phase space density,” which is a combination of position and momentum used as the figure of merit for attempts to get Bose-Einstein Condensation, by a factor of 350.

Asteroid and comet bombardment melted one of Jupiter's moons

Tue, 26 Jan 2010 22:26:47 +0100

Asteroid and comet bombardment melted one of Jupiter's moons:

John Timmer in Ars Technica describes a new model for formation in Jupiter’s moons:

The authors of the new paper focus on a period early in our Solar System’s history called the Late Heavy Bombardment. The record of impacts on the Moon suggest that gravitational disturbances sent about 1.6 x 10²²g of material into its surface, equally divided between comets and asteroids. That implies the disruption of a planetesimal disk that contained about 20 times the Earth’s mass, most likely via gravitational interactions with the gas giants. Obviously, a gravity well like Jupiter’s would attract a significant number of these bodies. More significantly, the planet would focus their trajectories such that the closer the moon to Jupiter, the more impacts it would receive. According to the authors, the Late Heavy Bombardment would strike Ganymede with about 80 times the mass than Callisto was hit with. They estimate that the total energy imparted to Ganymede could be up to 10³⁶erg [10³⁰ joules], enough to melt its ice five times over and allow all of the rocky material to sink to the core.

ESA Portal - Inside the dark heart of the Eagle

Mon, 25 Jan 2010 07:49:14 +0100

ESA Portal - Inside the dark heart of the Eagle:

Beautiful images returned from the European Space Agency’s new Herschel Space Observatory, orbiting the L2 Lagrange point of Sun-Earth, show star birth inside a dark cloud in the Eagle Nebula.

Embedded within the dusty filaments in the Aquila image are 700 condensations of dust and gas that will eventually become stars. Astronomers estimate that about 100 are protostars, celestial objects in the final stages of formation. Each one just needs to ignite nuclear fusion in its core to become a true star. The other 600 objects are insufficiently developed to be considered protostars, but these too will eventually become another generation of stars.

This cloud is part of Gould’s Belt, a giant ring of stars that circles the night sky – the Solar System just happens to lie near the centre of the belt. The first to notice this unexpected alignment, in the mid-19th century, was England’s John Herschel, the son of William, after whom ESA’s Herschel telescope is named. But it was Boston-born Benjamin Gould who brought the ring to wider attention in 1874.

symmetry breaking » Blog Archive » Strongly interacting dark matter ruled out by observations

Sat, 23 Jan 2010 20:52:48 +0100

symmetry breaking » Blog Archive » Strongly interacting dark matter ruled out by observations:

Symmetry Breaking reports on neutrino observations from the IceCube detector in Antarctica, which appear to rule out strongly interacting dark matter:

Although the majority of physicists favor models of dark matter that only rely on weakly interacting massive particles, or WIMPs, some theoretical models allow for strongly interacting massive particles, or SIMPs. Massive versions of each of these particles are whimsically referred to as wimpzillas or simpzillas.

Prior to this study, this plot represents the excluded types of simpzilla based on mass and interaction strength. The colored regions are all excluded by experiment with just the white triangles remaining as possible types of SIMPs. Like the other plot, this shows the SIMP types ruled out but with new data added. It cuts out the white triangles, leaving only a patch in the lower right, which does not correspond to any favored theories as the dark matter would be too massive.

During recent years, a range of underground and space-borne experiments have ruled out various combinations of interaction strengths and masses for dark matter particles, but there had always been a few openings left for particles of just the right combinations of interaction strength and mass. If simpzillas did exist, they would become captured by the gravity of massive objects such as the Sun. Then they would bump into each other, lose energy, and accumulate near the center of the Sun where they would annihilate, giving off neutrinos. Those extra neutrinos should be detectable by a neutrino telescope such as IceCube in Antarctica. Using data collected from 22 strings of IceCube’s optical modules, a fraction of the 80 strings that make up the entire detector, the physicists determined there was no excess of neutrinos coming from the Sun with enough confidence to rule out the existence of simpzillas.

"Humans are to a large degree sensitive to energy fluxes rather than temperatures, which you can..."

Fri, 22 Jan 2010 20:07:42 +0100

“Humans are to a large degree sensitive to energy fluxes rather than temperatures, which you can verify for yourself on a cold, dark morning in the outhouse of a mountain cabin equipped with wooden and metal toilet seats. Both seats are at the same temperature, but your backside, which is not a very good thermometer, is nevertheless very effective at telling you which is which.”

- Craig F. Bohren and Bruce A. Albrecht, Atmospheric Thermodynamics (Oxford University Press, 1998).

"On two occasions I have been asked, ‘Pray Mr. Babbage, if you put into the machine wrong figures,..."

Tue, 19 Jan 2010 19:07:00 +0100

“On two occasions I have been asked, ‘Pray Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’ In one case a member of the Upper, and in another a member of the Lower, House put this question. I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.”

- Charles Babbage, on politicians’ lack of understanding of (and refusal to fund) his work on the difference engine.

symmetry breaking » Blog Archive » CMS’ first measurement

Mon, 18 Jan 2010 21:36:58 +0100

symmetry breaking » Blog Archive » CMS’ first measurement:

Good news from the LHC in Symmetry Breaking:

One universal feature of high-energy particle collisions is that many charged particles are made during the interaction. When an experiment first begins colliding beams, the first thing physicists must do is to study these particles to verify that they have the same range of energy and spatial distribution as earlier measurements. In addition, it’s important for physicists to verify that the right numbers of charged particles are produced in each collision. Failure to verify could indicate a failure of the equipment or (and this is far less likely) a discovery.

After studying several of these distributions, the CMS results are in excellent agreement with earlier measurements and these results are likely to be CMS’ first publication. The speed at which these results have become available is a testimony to all of the hard work that has gone into designing and building the equipment, the grid computing and analysis software, as well as the enthusiasm and expertise of the analyzers.

Two-qubit quantum system used to model the hydrogen molecule

Sun, 17 Jan 2010 20:06:27 +0100

Two-qubit quantum system used to model the hydrogen molecule:

Ars Technica describes a groundbreaking development in quantum computing:

To model a hydrogen molecule (two bonded hydrogen atoms), scientists injected two photons into an optical circuit, with each photon’s polarization representing the encoding for a “control” qubit and a “register” qubit. The register represents an eigenstate, or one accepted energy configuration of the hydrogen molecule, and the control is in an equal superposition of a vertical and horizontal polarization.

The photons are then passed through a logic gate that represents an evolution of the wave function over time. The gate polarizes the control photon, forcing it to collapse into either a vertical or horizontal state. It also performs an operation on the register photon if the control comes out of the gate horizontally polarized, or leaves the register photon alone if the control becomes vertically polarized. The position of the control photon is measured and converted to a bit—0 for horizontal, and 1 for vertical. This represents one pass through the optical circuit.

First Direct Measurement of an Exoplanet’s Light Spectrum | Wired Science | Wired.com

Sat, 16 Jan 2010 21:11:53 +0100

First Direct Measurement of an Exoplanet’s Light Spectrum | Wired Science | Wired.com:

Using the Very Large Telescope in the Chilean desert, astronomers were able to see the infrared spectrum of the exoplanet HR 8799c, 129 light-years away from Earth. Though this planet is a gaseous planet larger than Jupiter and not habitable, scientists could use the same technique to find the telltale atmospheric signals of gases like water vapor and nitrogen on Earth-like planets by measuring variations in the color of the planet’s light.

“The spectrum of a planet is like a fingerprint. It provides key information about the chemical elements in the planet’s atmosphere,” astronomer Markus Janson of the University of Toronto, who led the work, said in a press release. “With this information, we can better understand how the planet formed and, in the future, we might even be able to find telltale signs of the presence of life.”

SEEDMAGAZINE.COM § Workbench: Neil deGrasse Tyson

Fri, 15 Jan 2010 17:51:40 +0100

SEEDMAGAZINE.COM § Workbench: Neil deGrasse Tyson:

Neil deGrasse Tyson, Director of the Hayden Planetarium at the American Museum of Natural History, describes some of the objects in his office to Seed Magazine, including a nice, unusual-looking lamp:

I made that lamp as a 12-year-old in seventh-grade wood shop class. The task was to make a lamp, and they offered us all of these prefabbed plans to use. And I said no, no, no, I’m going to make my own damn lamp. I knew what I wanted: I wanted to make Saturn.

He also comments about being a public scientist, and the obligation to teach as well as research:

On the top shelf there, I hide away many of my awards, the majority of which I’ve received for science outreach and public awareness. It’s an honor to be recognized for it. But in a fantasy world, I would stow away somewhere to only do astrophysics research. The thrill of discovery brings me great pleasure. But even university professors, at some point, need to teach a class in order to earn their keep.