On the origin of extinction in the Coma cluster of galaxies

Visual extinction of distant clusters seen through the Coma cluster seem to suggest that dust may be present in the hot x ray emitting intracluster gas. However, the Infrared Astronomy Satellite (IRAS) failed to detect any infrared emission from the cluster at the level expected from the extinction measurements. Researchers carried out a detailed analysis of the properties of intracluster dust in the context of a model which includes continuous injection of dust by the cluster galaxies, grain destruction by sputtering, and transient grain heating by the hot plasma. Computed infrared fluxes are in agreement with the upper limit obtained from the IRAS. The calculations, and the constraint implied by the IRAS observations, suggest that the intracluster dust must be significantly depleted compared to interstellar abundances. Researchers discuss possible explanations for the discrepancy between the observed visual extinction and the IRAS upper limit

Bayesian Program Learning

Article contribution towards Edge.org's annual question. This one will be about a new type of artificial intelligence

What Do I Think About Machines that Think?

No abstract availabl

Politics and Prophecy

No abstract availabl

Fiat Lux, Let There Be Light!

Most of us think of light as helping us see things, but it is so much more important than that. Light is electromagnetic energy moving in waves through space, interacting with atoms and molecules as it goes. So are radio waves, microwaves, infrared light, ultraviolet, x-rays and gamma rays - all of them are electromagnetic energy, and the only real difference is the spacing between the wave crests. So light gives us communications with each other with radio and TV, and it gives us the ability to travel through the universe using telescopes and our imagination. But light also gives us access to scientific questions, such as: what holds the atoms and molecules together? How does the mysterious quantum mechanics work? And understanding all these, how can we build electronic devices for modern life? And if we are very ambitious, we build accelerators like the Large Hadron Collider, and particles collide and concentrate electromagnetic energy into tiny spaces, and according to Einstein's E equals mc squared, we turn energy into new particles to learn, perhaps what the universe was like when it was a tiny fraction of a second old

Our History in the Stars

John C. Mather is senior project director of NASA's James Webb Space Telescope (JWST), successor to the Hubble Telescope. Nearly cancelled in summer 2011 during a flurry of federal budget cuts, the project was fully funded by Congress in November 201l. Fellowship spoke with Dr. Mather about his thoughts on the importance of funding space science and the JWST

Interview Questions with Bentham Scientific

John Mather answers questions for an interview for the Bentham Science Newsletter. He covers topics ranging from his childhood, his professional career and his thoughts on research, technology and today's scientists and engineers

Book Review for Physics Today Ostriker and Mitton

Can anyone explain to a general audience how astronomers converged on such an astonishing story as the Big Bang, with large doses of Dark Matter and Dark Energy that only astronomers can see and most astronomers didnt want? Might the reader believe the answer? And can the story keep the attention of professional physicists? The answer is yes for Unraveling the Mysteries of the Invisible Universe by Jeremiah Ostriker and Simon Mitton (Princeton University Press, 2013). Ostriker, a theorist, is one of the modern pioneers of the subject, and Mitton, a physicist-journalist, is an excellent storyteller as well