Saturday, April 24, 2010

Paleocene-Eocene Thermal Maximum

Did Monster Eruptions Warm the World? in Science.
The Paleocene-Eocene Thermal Maximum occured 55 million years ago. Temperatures rose over 5C and there were mass extinctions - many classes of current mammals arose afterwards. Researchers have recently found evidence of massive undersea volcanic eruptions near Iceland from that time period. The volcanic release of methane may have caused the warming.

Friday, April 23, 2010

Dark Matter Review Article

Dark Matter in Modern Cosmology preprint.
The presence of Dark Matter (DM) is required in the universe regulated by the standard general relativistic theory of gravitation. The nature of DM is however still elusive to any experimental search. We discuss here the process of accumulation of evidence for the presence of DM in the universe, the astrophysical probes for the leading DM scenarios that can be obtained through a multi-frequency analysis of cosmic structures on large scales, and the strategies related to the multi-messenger and multi-experiment astrophysical search for the nature of the DM.

Sunday, April 18, 2010

Cosmic microwave background anisotropies

Lecture notes on the physics of cosmic microwave background anisotropies
We review the theory of the temperature anisotropy and polarization of the cosmic microwave background (CMB) radiation, and describe what we have learned from current CMB observations. In particular, we discuss how the CMB is being used to provide precise measurements of the composition and geometry of the observable universe, and to constrain the physics of the early universe. We also briefly review the physics of the small-scale CMB fluctuations generated during and after the epoch of reionization, and which are the target of a new breed of arcminute-resolution instruments

Dark Energy

Why all these prejudices against a constant?
The expansion of the observed universe appears to be accelerating. A simple explanation of this phenomenon is provided by the non-vanishing of the cosmological constant in the Einstein equations. Arguments are commonly presented to the effect that this simple explanation is not viable or not sufficient, and therefore we are facing the "great mystery" of the "nature of a dark energy". We argue that these arguments are unconvincing, or ill-founded

Galaxy Structure

The Universal Faber-Jackson Relation
In the context of modified Newtonian dynamics, the fundamental plane, as the observational signature of the Newtonian virial theorem, is defined by high surface brightness objects that deviate from being purely isothermal: the line-of-sight velocity dispersion should slowly decline with radius as observed in luminous elliptical galaxies. All high surface brightness objects (e.g. globular clusters, ultra-compact dwarfs) will lie, more or less, on the fundamental plane defined by elliptical galaxies, but low surface brightness objects (dwarf spheroidals) would be expected to deviate from this relation. This is borne out by observations. With MOND, the Faber-Jackson relation (the power-law relation between luminosity and velocity dispersion), ranging from globular clusters to clusters of galaxies and including both high and low surface brightness objects, is the more fundamental and universal scaling relation in spite of its larger scatter. Faber-Jackson reflects the presence of an additional dimensional constant (the MOND acceleration) in the structure equation

The mass distribution in Spirals
In the past years a wealth of observations has unraveled the structural properties of the Dark and Luminous mass distribution in spirals. These have pointed out to an intriguing scenario not easily explained by present theories of galaxy formation. The investigation of individual and coadded objects has shown that the spiral rotation curves follow, from their centers out to their virial radii, a Universal profile (URC) that arises from the tuned combination of a stellar disk and of a dark halo. The importance of the latter component decreases with galaxy mass. Individual objects, on the other hand, have clearly revealed that the dark halos encompassing the luminous discs have a constant density core. This resulting observational scenario poses important challenges to presently favored theoretical

Tuesday, April 13, 2010

DSLR with nice HD Video Capabilities

"The Last 3 Minutes"

"The Last 3 Minutes" From Shane Hurlbut, ASC from Shane Hurlbut, ASC on Vimeo.

shot with the Canon 5D Mark II DSLR. Try to watch in full screen mode with HD on by following the link that's mentioned.

One Hedge Fund that made money fueling the Bubble

The Magnetar Trade: How One Hedge Fund Helped Keep the Bubble Going at ProPublica.
"A hedge fund, Magnetar, helped create arcane mortgage-based instruments, pushed for risky things to go inside them and then bet against the investments"

Sunday, April 11, 2010

More about the mathematician Perelman

He Conquered the Conjecture by John Allen Paulos in the New York Review of Books is a review of Perfect Rigor: A Genius and the Mathematical Breakthrough of the Century by Masha Gessen a biography of the Russian mathematician Grigoriy Perelman who recently solved a long-standing problem in topology, the Poincaré conjecture.

Markets, Theory and Reality

Hedging America by Robert M. Solow in the magazine The New Republic. Solow is a Nobel Prize winning economist who also happened to teach my macroeconomics class at MIT many a moon ago. The article discusses the theory behind markets and how the reality from time to time falls conspicuously short.

Friday, April 09, 2010

The Economics of Dueling

The Deadliest of Games: The Institution of Dueling.
Recent historical research indicates that ritualistic dueling had a rational basis. Basically, under certain social and economic conditions, individuals must ght in order to maintain their personal credit and social standing. We use a repeated two-player sequential game with random matching to show how the institution of dueling could have functioned as a costly but incentive-compatible means by which individuals could demonstrate their good faith dealings by defending their "honor".

Saturday, April 03, 2010

More Evidence for Cosmic Acceleration

Astrophysics: Cosmic acceleration confirmed in Nature.
Evidence for the accelerated expansion of the Universe from weak lensing tomography with COSMOS: astrophics preprint.

Why was the ancient Earth so warm?

Early Earth: Faint young Sun redux Early in the Earth's history (several billion years ago) it is thought that the Sun was dimmer, so much so that the oceans would have been frozen. However there is ample evidence that the oceans were mostly liquid during that period. Greenhouse gases in the atmosphere may have kept the Earth warm. But there's a new theory that the Earth's surface may have also been darker in the past, allowing it to retain more heat from the fainter sun and resulting in warmer temperatures.

Prospects for Personal Genomics

Multiple personal genomes await by J. Craig Venter in Nature. Gene sequencing pioneer Venter reviews the current state of the art. One difficult problem is due to chromosomes occuring in pairs, one from each parent. Apparently it isn't easy to distinguish the two copies and the differences between them.

Ice Age Flood went to the Arctic not Atlantic

River reveals chilling tracks of ancient flood in Nature. After the end of the last ice age there was another cool period, the Younger Dryas, 13,000 years ago. One theory was that a huge freshwater lake in Canada, formed from melted glaciers, suddenly drained into the North Atlantic, disrupted the warm water conveyer belt there, resulting in a resumption of cold conditions in the Northern Hemisphere. But now it appears that instead Lake Agassiz drained north into the Arctic Ocean. Did that flood still cause the Younger Dryas cold period?

Chemistry of the Ancient Oceans

Ocean Chemistry and Early Animals in Science. Animal life requires oxygen. What stages took place before the current oxygenated ocean chemistry and animal communities beccame established around 542 million years ago?

Quark Masses

Mass of the Common Quark Finally Nailed Down in Science.
Currently there are six known flavors of quarks, each with a different mass. The masses haven't been known with much accuracy, in part because quarks are never found in isolation, they are are always found bound with other quarks. The binding interaction is so strong that most of the mass of the bound particle (like a proton or neutron) is due to the energy of interaction. These new theorectical calculations may give the quark masses to a greater degree of accuracy.

Friday, April 02, 2010

Powerful People are Better Liars

Powerful Lies an article from Columbia Business School.
"Most people become stressed when lying, but new research shows that people with power feel just fine when lying — and are better at getting away with it."