This page is meant to be
a collection of miscellaneous scientific information,
mostly concerning physics and mathematics.
Using ESA's XMM-Newton satellite and the Chandra Space Telescope, a Southampton-based team has discovered a black hole in a globular star cluster associated with the elliptical galaxy NGC 4472, some 55 million lightyears away. The find is significant, as the prevailing thought has been that gravitational interaction with stars tends to slingshot black holes out of globular clusters. Still more excitingly, one interpretation of the X-ray data suggests that the mass of the object is a whopping 400 solar masses or more. Some numerical models indeed predict the formation and growth of such "intermediate mass" black holes by successive mergers with stellar mass objects. In the next decade, gravitational waves from neutron stars or small black holes spiraling into an intermediate mass black hole may be detected by Advanced LIGO, as pointed out in gr-qc/0607092.
The Nobel Prize in Physics 2006 went to John C. Mather and George F. Smoot "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation". Both were heavily involved in interpreting data from NASA's Cosmic Background Explorer. The anisotropies they found provided us with our first glimpse of density perturbations just a few hundred thousand years after the Big Bang, which would be the seeds of galaxy formation. Later on the Wilkinson Microwave Anisotropy Probe improved upon their measurements, leading to a corroboration of the standard model of cosmology together with an accurate determination of the composition and present age of the Universe.
String theory is finally being critized in a serious way. A recent book by Peter Woit, Not Even Wrong, points out that string theory has failed to produce useful results, and he questions whether it should be allowed to dominate theoretical particle physics to the exclusion of almost any other line of research. A similar book by Lee Smolin is entitled The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next.
In an article in the journal Science, J. Wisdom described a beautiful
relativistic effect dubbed "spacetime swimming". As it turns out, bodies
undergoing cyclic deformations are able to speed up, slow down, or change
their path as they move through curved spacetime. The model body being
considered takes the form of a tripod, the legs of which can open and close
as well as vary their lengths, so that the "swimming" is eerily similar to
the way a squid moves in water. There are some differences though: although
it helps to have large variations in leg length, contrary to what one might
expect it is counter-productive to swing the legs with high frequency.
Swimming enthusiasts (or indeed people accidentally falling off tall
buildings) should not get too excited by all this: the effect is absolutely
tiny due to the prefactor of G/c^2 (of order 10^-28 m/kg) in the expression
for the displacement. See the
paper by Gueron et
al. for a clear and concise technical description.