When a star with mass similar to our own Sun expends all of its fuel, it settles into becoming a white dwarf. If the star was made up of frictionless, non-quantum mechanical matter, there would be nothing from stopping the star from collapsing into a black hole.
However, all matter are of a quantum mechanical nature, so if matter is packed in tightly enough, degeneracy pressure exerts itself, which is the result of the Pauli exclusion principle, where no two fermionic particles of the same type can occupy the same quantum state. In a white dwarf, electrons are packed so tightly together such that if they get packed any tighter some electrons would end up in the same quantum state, so a pressure that fights against further packing is exerted. This electron degeneracy pressure prevents the star from collapsing into a singularity.
If a star has more than 1.4 times the mass of our Sun, though, then the electron degeneracy pressure is not enough to keep the star from collapsing. Then the particles in the star combine into a homogeneous soup of neutrons, which in turn exert a neutron degeneracy pressure. For stars with up to 2 to 3 times the mass of our Sun, this is enough to prevent gravitational collapse and they exist as neutron stars.
However, neutron degeneracy pressure is not enough for stars with even larger mass. Either the star could collapse into a black hole, or the neutrons could disintegrate into free quarks, and further collapse would be prevented by the quark degeneracy pressure. The thing is that a neutron is probably about 50 to 200 times the mass of its constituent quarks, so a lot of energy should be released when a neutron star collapses into a quark star.
And now Canadian researchers may have identified supernovae explosions which may have resulted in quark stars. These explosions were about 100 times brighter than the typical supernova explosion, and they believe that the release of energy as a neutron disintegrates into its constituent quarks during the formation of quark stars could explain why they are so much brighter. If their hypothesis is confirmed, then we'll need to add one more type of star to the textbooks.
About 130 people were injured during a violent clash during protests against the importation of American Beef into South Korea. By now, most of the moderates who participated in the protests are probably tired of them and need to go back to their own lives, so it's not a particular surprise that only the hardcore protestors would still go on. So it would have only been a matter of time before the ongoing protests resulted in violence.
The ironic thing is that for all we know, the injuries from this single protest might be more harm than what could result from the import of US beef, at least in terms of Creutzfeldt-Jakob disease infection. It is quite possible that no such cases might arise at all. I could be wrong, and the protestors could be right in their belief that import of US beef could result in a rash of cases, but there is no indication that this would be the case.
The Bureau of Land Management, which manages public land in the United States, has put a two-year moratorium on new solar plant proposals on public land. The good news is that the moratorium is motivated by the large number of proposals that have been made, which implies that a lot of companies are interested in solar energy as a significant source of energy in the near future. This is a hopeful sign that cleaner energy sources are on the rise.
The bad news is the moratorium itself. The Bureau is imposing the moratorium because they want to make sure that the environmental impact from the large number of solar plants will not be too adverse. I have mixed feelings about it. On the one hand, it's reasonable to be cautious about deploying a new type of energy plant on a wide scale and to make sure that the environment is not affected too much. On the other hand, this will impede progress in the solar energy industry, which could put the brakes on the deployment of clean energy sources.
The problem is made worse by the fact that tax credits for investing in new solar plants will expire at the end of the year, so it could put an abrupt halt to investments in solar energy. I just hope that Congress will renew the tax credits. And I really hope that this is not a sneaky attempt by the Bush administration to prolong the dependence on non-renewable, carbon emitting energy sources.
GLAST, the space-based gamma-ray observatory from NASA, is now operational and has started collecting data. GLAST will be able to observe much higher energy gamma rays compared to the Swift satellite, which should open a new view to the skies.
While it's a sure thing that GLAST will be observing known things such as gamma-ray bursts, active galactic nuclei, and supernova remnants, it might even make breakthroughs in physics by observing annihilation of dark matter particles or violations of Lorentz invariance.
The computer graphic for GLAST in orbit is courtesy of NASA.
Socialism seems to be alive and well in America, despite rhetoric to the contrary. The government bailed out Bear Stearns with a very large subsidy, while Congress has passed a law to support homeowners that are in danger of foreclosures. Not that this is necessarily a bad thing, but there's a slight cognitive dissonance in that a lot of people in power extol the virtue of a pure free market with minimum regulation.
Of course, the severe economic downturn is in large part due to the deregulation frenzy the current administration has been on (there probably still would have been a downturn, but it wouldn't have been as severe without the administration's policies). So it's a little funny to see them trying to fix problems caused by a free market agenda with socialist solutions. The White House seems to only support corporate socialism, though, since there was nary a peep from them concerning the Bear Stearns bailout, while they threatened a veto of the homeowner relief bill.
For the record, I'm neither a pure capitalist nor a pure socialist. I prefer a mix and match of whatever works.