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- One of the most spectacular discoveries over the past 100 years is that the Universe is expanding. And, it is expanding at ever accelerating rate. Galaxies are rapidly separating from each other and some are going out of sight.
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- When the General Relativity equations were produced in 1905 - 1915, the equations were “ unstable”. They defined a Universe that was like balancing a pencil on its point. Any tilt, in any direction , would result in the Universe expanding forever, or, compressing back into a single point, a “singularity“.
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- Einstein came up with another term to put in his equation to solve this problem. He called it a “Cosmological Constant“, with values selected to balance the equation into a “static” condition. That was what he thought the Universe was doing at the time. It was static.
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- Hubble later in 1915 discovered the Universe was expanding. The further a galaxy was away from us the faster it was receding away from us. So, the Cosmological Constant needed to change its values to allow for an accelerating, expanding Universe. Distant galaxies the further away the faster they were separating from us. Those at the most distant boundary were too far for enough time to allow light to reach us. They are past a horizon beyond which a galaxy will never be seen again.
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- The conclusion became that the fabric of space itself was expanding everywhere overcoming the pull of gravity. The pull of gravity (F) decreases at the square of the distance of separation ( r )
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----------------------------- F = G * M * m / r^2
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- Fine, I can buy that but what is the Universe expanding in to?
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- Hard to comprehend, but, space itself is growing everywhere the same as time is expanding everywhere. Denser regions draw in more and more matter creating a “Lumpy” distribution with expanding “voids” in between.
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- What is causing this expansion? The name given is “ Dark Energy”.
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- Today the rate of expansion is 47,000 miles per hour per every million lightyears distance
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------------------------- Distance * 47,000 mph/MLY = receding velocity.
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- We can not see beyond how far light has traveled over the past 13.6 billion years. Beyond that horizon is the “Unobservable Universe” that we can never see.
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- So, we are free to let your imagination wander. Could the Universe eventually fold back on itself?
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- If looking east and a galaxy disappears. Could you turn the telescope pointing west and see it come back over the horizon?
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- Or, is our Universe inside a bigger Universe?
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- Or, are there multiple Universes and are we just in one of many?
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- All we have to hang our hat on is the equations in General Relativity that shows how space could be expanding. Even between our ears.
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- A brain once expanded never returns to its original size.
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- Physics has something to say about the temperature of the Universe decreasing as the size increases. At the time of the Big Bang the temperature was 1.4*10^32 Kelvin. Today the Universe has expanded and cooled to 2.73 Kelvin.
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- If you take the clock back to the beginning the smallest increment of time is theoretically 10^-43 seconds. If you use the natural constants to calculate the mass the equation becomes:
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--------------------------- mass^2 = h * c / G
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------------------------- h = Planck’s constant = 6.58 * 10^-22 MeV*sec
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-------------------------- c = constant speed of light = 2.99*10^8 m / sec
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------------------------- G = Gravitational Constant = 6.67*10^-11 m^3 / kg* sec^2
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-------------------------- MeV = 1.6022*10^-13 kg^ * m^2 / sec^2
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-------------------------- m^2 = 4.73 * 10^-16 kg^2
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-------------------------- m = 2.2*10^-8 kg
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- Planck mass 2.2 * 10^-8 kilograms doesn’t sound like much but it is equivalent to 10^19 protons And, the energy equivalent using E = mc^2 = 1.23 * 10^19 GeV.
That is a tremendous amount of energy.
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- It is embarrassing for astronomers that the evidence suggests 95% of the Universes’ mass-enregy is something we have not discovered to date. 70% is Dark Energy. 25% is Dark Matter.
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- The Universe we see, know a little about, and love is only 5% of what is out there.
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- The search for Dark Matter is pushing technologies to new limits. Some current experiments are located one mile underground in South Dakota. These technologies are using Xenon detectors.
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- Xenon has the atomic number 54. It is a colorless, dense, odorless, noble gas. It is used in flash lamps in lasers and in the search for weakly interactive massive particles (WIMPS) believed to be the source of Dark Matter.
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- The evidence for Dark Matter’s existence is the unseen gravity found around galaxies. Unseen gravity that acts as a lens bending light beams to magnify even more distant galaxies.
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- The Xenon detectors are located deep underground to reduce interference from any other particles. The search depends on the accuracy of current theories. Every new clue produces new theories.
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- General Relativity was the theory used to detect gravitational waves in the LIGO experiment. The Laser Interferometer Gravity Observatory discovered these waves for the first time last September, 2015. This same theory is being used as the only evidence for Dark Matter depending on our same understanding of gravity.
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- Gravitational Waves are distortions , or ripples, in the fabric of space-time. WIMPS are particles that have mass affected by gravity, but, these particles do not interact with electromagnetic radiation.
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- The science of cosmology and the expansion of the Universe is used to calculate how much Dark Energy is out there and Gravitational Lensing is what has given astronomers a pretty good idea of how this Dark Matter is distributed. It is effectively invisible halos surrounding the visible galaxies containing at least 5 times the mass we can see.
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- What we do not know is what this invisible mass is at the particle level. That is what these experiments are all about. A brain once expanded never returns to its original size.
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- Request these Reviews to learn more:
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- #1821 - Describing the Universe.
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- #1821 - also list 15 other Reviews.
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- #1808 - History of the Universe, 16 pages long.
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- --------------------------------------------------------------------------------------
---- Comments appreciated and Pass it on to whomever is interested. ----
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
- to: ------- jamesdetrick@comcast.net ------ “Jim Detrick” -----------
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----- 707-536-3272 ---------------- Monday, March 7, 2016 -----
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