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-------------------------- 2430 - DARK ENERGY and Cosmic Inflation
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- Dark Energy was discovered in 1998 when astronomers measured light from supernovae exploding in distant galaxies. The conclusion they reached was that the galaxies further away were accelerating away faster than expected. Gravity should be slowing expansion down. Something more powerful is speeding it up.
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- There is no way to detect Dark Energy directly so we have to measure its “effects“. The main effect is the acceleration of distant galaxies. If Dark Energy is vacuum energy in empty space it is ridiculously small. Using quantum mechanic equations to calculate the amount of vacuum energy physicists get an amount that is 10^120 times greater than what we observe. ( That is 1 followed by 120 zeros, a ridicules number!.)
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- If Dark Energy comes from Einstein’s Cosmological constant, or, if it comes from the theory of Quintessence, it will vary over time and distance. If Dark Energy is a modification to our theory of gravity that too would vary over time and distance. Astronomers are studying more and more galaxies to gather data that will determine how much Dark Energy has changed over time.
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- In 1981 Alan Guth , a young physicist in Massachusetts, proposed an absurd idea. That the Universe went through an ultra-fast expansion just after the Big Bang. Called “Cosmic Inflation” the theory solved several major problems in cosmology. Like, why the shape of the Universe appears flat. Why the Universe appears the same in all directions; it is homogeneous, smooth and uniform. And why the Universe appears the same regardless of where the observer is in it; it is isotropic.
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- The Inflation theory has not been proven but some very good supportive evidence has come from study of the Cosmic Background Radiation. Galaxies at 100,000,000 lightyears dimensions form chains and clusters, however, on scales of billions of lightyears the Universe appears almost uniform. Like us standing on the surface of the Earth, the Universe is so large it appears flat from our perspective.
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- Guth’s theory had the Universe expanding by 10^30 times in a fraction of a microsecond. This enormous expansion was bound to flatten everything out. He came up with a physics explanation of how this could happen.
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- Guth proposed a phase transition occurred like the phase transition of water freezing. The liquid Universe could have been in a super-cooled state and crystallization occurred in an instant. The energy to make this happen would come from vacuum energy, and that is what Dark Energy appears to be coming from, vacuum energy in empty space.
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- With Cosmic Inflation a tiny bubble can inflate to the size of the entire Universe in an instant. A factor of 10^60. ( Thai is a one followed by 60 zeros!)
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- When we observe the Cosmic Background Radiation we can see the inflationary wrinkles, of ripples, originally set in place by quantum vibrations when the Universe was the size of an atom. These vibrations became wave-like density fluctuations vibrating through matter in the early Universe like sound waves. These variations in density and pressure are what allowed the stars and galaxies to form.
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- The hot and cold spots which today only vary by 100,000th of a degree reflect denser and rarefied regions of space. The denser regions had gravity that made them more dense until density and temperature created nuclear fusion and started the stars.
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- Can we truly prove anything in astronomy? Many theories are beautiful but that is not sufficient to prove them “right“.
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- More observational evidence is needed to prove these theories. The ability to measure polarization in the Cosmic Background Radiation is a breakthrough that can give us more information. Observing gravitational waves is another opportunity.
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- We need data to explain “ Dark Matter” that appears to be supplying extra gravity around galaxies. Likewise we need data to explain “ Dark Energy” that appears to be accelerating the expansion of the Universe.
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- Radiation travels at finite speed, 186,000 miles per second. The further away we see a source the farther back in time the radiation was emitted. Using visible light radiation we can see back to when the Universe was 17% its current age, when it was 2,300,000,000 years old.
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- Using microwave radiation we can see when the Universe was 0.1% its current size, when it was 370,000 years old. Each look back capability gets us closer to the Big Bang and to a better understanding of the Universe.
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- See other Reviews on this topic:
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- 2337 - A force in the Universe we do not know.
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- 2297 - Dark Matter and Dark Energy make up 23% and 72% of the Universe. Everything else is only 5%. We have a lot more to learn.
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- 2257 - What is the fate of our Universe? This Review lists 11 more reviews on the topic.
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- 744 Universe Expansion,
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- 718 Dark Matter,
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- 715 Cosmic Dark Ages,
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- 713 Cosmological Constant,
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- 702 Birth of the Universe.
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- August 8, 2019 756
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--------------------- Thursday, August 8, 2019 --------------------
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