Cosmology

Here is the fifty-second episode of Quantum Foam, Cosmology. The current sound set-up seems to be working good with minimal background noise. I want to give an up-to-date description of this subject. Cosmology is the scientific study of the universe as a whole. This is the branch of science that asks the biggest questions of them all. Cosmologists treat the whole universe as one object. This area is one of the most active parts of physics. That is why we are taking the time to go over this. Astronomy observes phenomena within the cosmos. Astrophysics explains the physics of how objects form, shine, and behave. Astrology, on the other hand, is not even a science. Each area has a clear focus. Cosmology is a special branch of Astronomy and Astrophysics. Astrology plays no part in cosmology. Cosmology has been built many times. George Lemaître proposed that the universe is expanding and began from a single, dense point. Edwin Hubble proved that galaxies are racing away from us, confirming the expansion by observation. The Big Bang is the leading explanation for how the universe began. In the first fraction of a second, the universe went through inflation. Within minutes, the first atomic nuclei formed, mostly Helium with traces of Deuterium and Lithium. The expanding universe is probably the single most important discovery in cosmology. When astronomers measure the light from distant galaxies, that light is stretched toward the red end of the spectrum. A redshift. The rate of expansion is called the Hubble Constant. Dark energy fills all of space. Properly explaining this idea is 1 of the field's central goals. We are actively attempting to do this as we speak. In 1965, 2 radio astronomers at bell labs, Arno Penzias and Robert Wilson, detected the Cosmic Background Radiation as a persistent hiss in their antenna. Cosmology is a field of study that brings together the natural sciences, particularly Astronomy and Physics, in a joint effort to understand the physical universe as a unified whole. The universe may be infinite without bounds. The ancient Greeks likened the Milky appearance seen in the sky to a river of milk. We are seeing the stars within our spiral galaxy edge-on. The Sun is a star around which Earth and other planets revolve. If the kingdom of the stars seems vast, the realm of the galaxies is larger still. Another decent-sized galaxy is the Andromeda galaxy and is also known as M31. This is from the Messier object catalog. When the universe is viewed in the large, a dramatic, new feature arises, namely, the cosmological expansion. The cosmic background radiation appears to be a ghostly remnant of the first light of the primeval fireball reduced by cosmic expansion to a shadow of its former splendor. It still pervades every known corner of the universe. In cosmological scales, the lengths become so vast that we are measuring light that takes a significant fraction of age of the universe to cross. Jordano Bruno asked the obvious question, if there is a boundary or edge for space, what is on the other side? He was burned at the stake in the year 1600. Johannes Kepler stated in 1610 that the number of stars in the universe had to be finite. Even if the universe is spatially finite, photons from very distant galaxies simply do not have time to travel to Earth because of the finite speed of light. We can't even in principle see past the age of the universe at about 13.8 billion years old. To derive his 1917 cosmological model, Einstein had 3 additional assumptions that lay outside the scope of his equations. The universe both had to be the same now and at the beginning. This universe is isotropic and homogeneous and has a closed spatial geometry. The universe as a whole was considered to be static, meaning the large-scale structure doesn't vary with time. This is an unchanging universe. This is an appealing idea and is called the perfect cosmological principle.