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----------------------------- 1930 - Gravity bends light.
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- The Hubble Space Telescope began using the magnifying power of gravitational lensing in December , 2012. The gravity is provided by a galaxy cluster that holds thousands of galaxies. X-rays show the gas inside the cluster glowing at millions of degrees.
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- It is the gravity provided by Dark Matter that is the glue” holding all these galaxies and gas together in a massive cluster. The Dark Matter represents 80 to 90% of the cluster’s total mass. Calculations put the mass at 1,000,000,000,000,000 Solar Mass ( 10^15).
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- The massive gravity warps space-time. The effect of bending space-time is to create an enormous gravitational lens. But, the lens is not pure. With magnification comes lots of image distortions. Light from the image follows multiple paths around and through the lens creating multiple distorted images. But, it is a magnified image if we could just clear up the distortion. Gravitational lensing allows astronomers to study faint , far away objects from the early Universe.
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- Hubble’s eyes can see infrared to ultraviolet. Hubble is looking at the same spot for 70 orbits around the Earth to get a long time exposure. The total observing time provides 280 exposures each 15 to 20 minutes duration.
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- Multiple time exposures allow astronomers to map the distribution of the mass within the cluster. The multiple images are of the same background object. A computer matches the positions of the warped images. The software varies the amounts and positions of Dark Matter until it reconstructs the same image each time.
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- These results allow astronomers to map the Dark Matter within the cluster and to learn how the Dark Matter behaves.
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- Secondly, this model of the lens allows a clear view study of the faraway galaxies. This process of matching images is a lot of trial and error. Then the astronomers got lucky. By using the computer to subtract new images from old images they identify what changes. With this technique they discovered supernovae explosions.
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- The single image of the supernova shows up at different times because the light has taken different times. The astronomers named the explosion Supernovae Refsdal. By studying how each image arrived, brightened , and dimmed astronomers cold accurately determine the distributions of mass in the gravitational lens. This brightness curve for a Type 1a Supernova is very well defined.
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- Multiple images arrived from November 3, 2014 to December 11, 2015. Five different images of the same supernova event. The Type 1a supernova has a well defined brightness curve that allowed the calculation of the “intrinsic brightness”. This in turn allowed a calibration of the amount of magnification of the gravitational lens.
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- The first stars living in these faint dwarf galaxies were pure hydrogen emitting ultra-violet light. This radiation kicked the electrons out of the hydrogen atoms creating a Universe of ionized gas. This was termed the era of “ re-ionizations”. An ear astronomers are anxious to explore.
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- The results of this astronomy has produced over 90 published scientific papers. There is still more to learn about the enormous galaxy clusters and their window into the earliest evolution of the Universe.
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- Dark Energy is a mysterious force that is 75% of the Universe’ mass-energy. It is the force that is expanding the Universe at an accelerating rate. Dark Matter is 25% along with ‘ Normal Matter” provides the gravitational pull on all matter and light.
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- Another result of gravitational lensing data is to produce a new “ Hubble Constant” for the rate of expansion of the Universe.
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------------------------ 71.9 + or - 2.7 kilometers per second per mega parsec.
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----------------------- accuracy to within = 2.7 / 71.9 = 3.8 %
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----------------------- 49,306 miles per hour per million lightyears separation.
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- So, you may be interested to learn that is how fast you are traveling towards the edges of the Observable Universe. Hold on. An announcement will be made shortly.
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- Note (1): Also see Reviews #1404, #1199, …………. The most distant galaxies measured have their light shifted 600% toward the red end of the light spectrum because the galaxy is receding away from us due to space between us expanding.
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----- 707-536-3272 ---------------- Thursday, February 9, 2017 -----
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