CapitalistImperialistPig

Back in the early days, when the Universe and I were young, the Universe (and I) were a hot dense plasma, with most of the mass and energy tied up in dark matter. A slight amount of clumping existed so dark matter and ordinary matter would fall together. Ordinary matter, being a plasma, dragged the radiation along with it, but as it collapsed, pressure would resist and cause re-expansion of ordinary matter (and the radiation along for the ride), producing oscillations. These oscillations could grow, but no faster than the speed of sound, probably about 2/3 the speed of light in a vacuum - but lots faster than the speed of light or other EM waves in the plasma. These oscillations produced slightly underdense bubbles with slightly overdense bubble walls. The maximum size to which a bubble could grow was thus limited by the speed of sound and the age of the universe. When the plasma cooled to the point that neutral atoms could form, radiation was freed from its plasma shackles and m...

When simulations of the early universe are done, matter (dark and normal) collects in very large scale [tens or hundreds of millions of light years] filaments of overdensity. Galaxies and stars develop in these filaments, the voids between them are largely empty of matter. Here and there - ok, mostly there - two filaments intersect. Such intersections are the breeding grounds of galaxy clusters and superclusters. The large concentrations of dark and normal matter in such clusters draws streams of gas from the filaments whose intersection marks the cluster, with the result that the cluster is bathed in a vast sphere of superheated (10^7 -10^8 K) but very low density (10^-7 to 10^-1 baryons/cm^3)gas. If two or more such clusters are close enough, their mutual gravitational attraction will propel them into high speed (10^7 km/hr) collision. These results can be spectacular, as in the case of the "Bullet Cluster" (Formal names: 1E 0657-56, 1E 0657-558) In the picture, t...

The curvature of spacetime produces non-euclidean behavior in light rays, and consequently multipathing and lensing effects. Einstein worked this out early - actually before he had the correct final form for the equations of General Relativity - but didn't publish it until 1936, and only then because he was pestered to by Rudi Mandl, a pesky Czech engineer. Einstein didn't consider the effect interesting or important. Fritz Zwicky knew better and recognized the potential immediately (1937). Almost another half-century had to pass before experiment caught up with theory. These are a few of the tidbits I have picked up in Evalyn Gates popular book Einstein's Telescope: The Hunt for Dark Matter and Dark Energy in the Universe . Viewed through a normal telescope, a quasar looks like a point of light, much like a star. (Hence the name quasi-stellar object, which is abbreviated to quasar.) However, if a massive galaxy lies directly between the quasar and Earth, what we observe...

One of the most mysterious things about the Universe is its apparent comprehensibility. After a few millenia, or a few hundred millenia of tinkering, we seem to have come up with a cosmogony and a theory of almost everything that explains a whole lot of the Universe and how it works. Twenty-five years ago we might have said everything. It would not have surprised our ancestors of a few centuries back if other planets, stars and galaxies had turned out to be made of utterly different stuff than us. But they aren't. Or at least the parts we see aren't. Even black holes turned out to be predicted by the theory of a guy who thought in terms of trains and elevators. The stars in those newborn galaxies of ten billion years ago turn out to be made of the same stuff that we are - the same quarks and electrons, the same chemical elements, that exist here and now. The first clear hint of stranger stuff came just about the time - 70 years ago - when the human race had pinned down a ...