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-------------------- 2550 - COSMOLOGY - the history of astronomy?
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- In 1930 Georges Lemaitre suggested the Universe originated with a primeval cosmic egg exploding and creating an expanding Universe.
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- In 1946 George Gamow proposed the expansion and cooling of a Universe from an initial state of infinite density and infinite temperature. All matter began as a state of protons, neutrons, and electrons, and as things cooled the elements came out of this nuclear cooking. However, the math calculations supporting this could not account for any element heavier than helium.
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- 1950 Fred Hoyle explained that the heavier elements were created later in the interior of stars. but, he favored a Steady-State Theory and did not believe in the Big Bang Theory. Hoyle’s theory required that matter always be created to fill the space as the Universe expanded.
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- In 1952 Pope Pious XII announced that the church favored the Big Bang Theory which affirmed the notion of a transcendental creator.
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- In 1955 Martin Ryle surveyed 2,000 radio sources with radio telescopes. Ryle argued that his data supported the Big Bang because older galaxies were more abundant and closer together in earlier times.
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- In 1948 Gamow’s paper stated that the Big bang Universe was first dominated by radiation, a raging sea of energy. As this expanded the energy would mostly be converted into matter, but, that a remnant of the radiation would remain. There would be a cosmic background radiation permeating all space.
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- As the Universe expanded it cooled. Starting out white-hot it would now be around 5 degrees Kelvin. In 1948 no equipment existed that could detect microwave radiation with a temperature below 20 Kelvin.
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- In 1963 Arno Penzias and Robert Wilson discovered the microwave background noise using a Bell Telephone labs microwave receiver. In 1965 they interpreted this to be about 3 Kelvin radiation left over from the Big Bang.
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- By1970 all the measurements supported the Big Bang and none supported the Steady-State theory. Cosmology had become an observational science not just a theoretical science.
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- In 1979 Alan Guth proposed a Cosmic Inflation occurring immediately after the Big Bang. This helped explain why the Universe appears Flat, rather than a Closed sphere or an Open saddle.
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- The initial density of the Universe is very close to the “ critical density”. If it were more dense gravity would stop the expansion and return the Universe in a Big Crunch. If it were less dense it would have flown apart so rapidly as to have died an early death as a Big Chill. Life has had time to exist only because the Universe is Flat and near critical density. The accuracy of this conclusion is one part in 10^60. That is a one followed by sixty zeros.
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- In 1992 George Smoot and John Mather reported satellite measurement data that found tiny differences from uniformity of the cosmic microwave background radiation. These tiny differences were the seeds for stars and then galaxies to form in our Universe. The started out as quantum fluctuations and ended up as galaxies and galaxy clusters after 13,700,000,000 years.
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- In 1930 Fritz Zwicky measured the rotational velocities of galaxies and concluded they should be flying apart. Something besides the gravity from mass we can see is holding them together.
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- By 1970 astronomers were convinced that visible matter was only 10% the mass of the Universe. 90% was Dark Matter.
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- By 1998 astronomers were convinced that the expansion of the Universe was accelerating and this had to be caused by some form of vacuum energy in space, Dark Energy.
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- Cosmology is on a cosmic journey into the darkness. Cosmology history began in 1543 Nicholas Copernicus proposed that the Earth was not the center of the Universe. It was a Sun-centered universe. Using circular orbit’s the math did not work out in order to predict the position of planets.
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- Later Johan Kepler concluded the planets orbit in ellipses. That therefore, planets’ orbital speed varied to sweep out equal areas over equal times. And, that the period of orbit squared is proportional to the radius cubed. Those changes allowed accurate predictions of the position of the planets.
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- Finally people started to believe were not the center of the Universe. Cosmology was a science from then on, but our scientific journey has still left us in the Dark, with 95% of the Universe being Dark Matter and Dark Energy that we do not understand. Let’s continue the journey
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- In 1990 the Cosmic microwaves are black body radiation was discovered as a faint glow of microwave radiation pervading the universe seemed like good evidence for the Big Bang. That radiation should show a precise pattern for its intensity at various wavelengths. If the radiation deviated from that pattern, known as a black body spectrum, then perhaps some non-Big Bang cause was responsible.
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- The measurements by the COBE satellite showed that the cosmic microwave radiation matched the black body spectrum perfectly. Opposing the Big Bang was no longer tenable. The theory held up.
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- Comic microwave background anisotropies provided new information. Everybody knew that the microwave background couldn’t be completely smooth, otherwise there would be no galaxies today.
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- The small seeds of matter that eventually grew into galaxies would have left an imprint in the temperature of the radiation, causing slight temperature differences (anisotropies) between different points on the sky. COBE was the first satellite to detect those differences and measure how big they were, crucial clues to piecing together the history of the universe.
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- In the year 2000 we learned that space is flat. In a great victory for balloon science, the BOOMERanG project flew around the South Pole and came back to its starting place. It measured the angles between ripples in the cosmic microwaves and concluded that the geometry of space was very close to perfectly Euclidean, in technical terms, “flat.” Showing that space on the whole was flat helped confirm the discovery of dark energy.
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- Quasars discovered in1963 were a great surprise at the time to finding bright objects literally on the outskirts of the visible portion of the universe. Quasars seemed like stars (quasistellar) but were too far away to see unless they harbored some enormously energetic phenomena. Quasars beamed radio signals or other electromagnetic radiation across the universe, providing a new source of information on events transpiring in the cosmos.
- In 1931 Dark Matter was first proposed by Fritz Zwicky. He noticed that the motions of galaxies in the Coma Cluster could not be explained by gravity if the only matter in the cluster was visible, giving off light. He deduced that a lot of the matter in the universe was dark.
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- Only much later did scientists realize that not only was most of the matter in the universe invisible, it was also of some type totally unlike the ordinary matter, which is composed primarily of protons and neutrons, found on Earth.
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- In 1998 Saul Perlmutter and Brian Schmidt shocked the cosmology community. Coming from two independent teams data from distant supernovas showed their brightness wasn’t quite right if the universe’s expansion had slowly been decelerating, as most experts had long believed.
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- Instead, the universe is expanding faster and faster. Accelerated expansion implies that something in space, now called dark energy, is pushing the cosmos apart.
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- In 2014 primordial gravity waves confirming that gravity waves really do exist thereby further validating general relativity. This discovery provides as sure a sign as you can get that inflation instantly after the Big Bang set the stage for the future evolution of the cosmos.
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- This discovery may also turn out to imply the existence of an infinity of parallel universes, as most versions of inflation require that our universe is just one of many big spacetime bubbles, a multiverse.
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- in 1964 the Cosmic microwave background radiation was discovered by accident. Penzias and Wilson found out that no matter how much they cleaned their radio antenna, it still recorded static from everywhere in space. That static was the echo of the birth of the universe, literally the smoke from the Big Bang gun, in the form of microwaves. That radiation was leftover from the Big Bang fireball, very hot at the beginning, but now less than 3 degrees above absolute zero.
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- In 1925 Edwin Hubble using the most powerful telescope available, detected a star in the Andromeda nebula that varied in brightness on a regular schedule. Such “Cepheid variables” had been used by Shapley himself to gauge the distance scale of the Milky Way, so he had to concede when Hubble showed that Andromeda was vastly far beyond the Milky Way’s outskirts.
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- Confirmation that the Universe is expanding, Hubble, using data collected by Vesto Slipher and Milton Humason, published the definitive analysis establishing that the cosmos actually is growing bigger. It was the greatest intellectual upheaval in the human conception of the cosmos since Copernicus.
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- The most incomprehensible thing about this history of astronomy is that we are here trying to comprehend it.
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- December 20, 2019 2550 759
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