Wednesday, November 9, 2022

3736 - Age of the Universe?

  -  3736  -    Age of the Universe?   Astronomers can determine the age of the universe by analyzing light and other types of radiation traveling from deep space.  If the Universe is 13.8 billion years old then that is how long it took that light to reach us.  How has what we are looking at changed over the time it took to reach us?            


---------------------  3736  -  Age of the Universe?                  

-   The universe is about 13.8 billion years old.  How do we know that?

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-  Scattered across the vacuum of space are stars, galaxies, stellar remnants and other objects that are billions upon billions of years old. The age of the universe is now thought to be about 13.8 billion years. 

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-  In the 1920s, astronomer Edwin Hubble came up with a way to figure out the relationship between the distance of an object, based on how long its light takes to reach Earth, and how fast it is moving away from us, based on how much light from distant locales has redshifted, or moved toward the lower-energy, or redder, end of the electromagnetic spectrum. 

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-   This metric, now known as the “Hubble constant“, describes the expansion of the universe at different locations. The Hubble constant is higher for objects that are farther away, and vice versa, suggesting that the expansion of the universe is accelerating. One consequence of this finding is that the estimated age of the universe is more difficult to prove since it is on the move.

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-  Right now, the universe is thought to be 13.8 billion years old. This was determined by evaluating data from the European Space Agency's “Planck spacecraft” and analyzing data from the “Atacama Cosmology Telescope” (ACT) in Chile. 

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-   Both the spacecraft and the telescope mapped the “cosmic microwave background” (CMB), which is leftover light from the Big Bang. By combining those data with existing models of how fast different types of matter and celestial objects would have appeared after everything began, scientists were able to estimate how far back that explosive birth of the universe happened. 

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-  Light leaving the early Universe gets stretched in its wavelength as it travels through expanding space.  When it gets to us it has stretched to the microwave wavelengths.  

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-  Light from the CMB emerged 400,000 years after the Big Bang and has been traveling ever since in that expanding space.  . The universe started out as scorching plasma, in which packets of light, or photons, were attached to electrons. It eventually cooled enough for photons to break free of the electrons, leave the plasma and scatter throughout space, forming what is now known as the CMB. 

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-  By measuring how far away such scattered light is, and how much it has stretched scientists can estimate of how old the universe is.

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-   The newest estimate of 13.8 billion years old was announced in 2020.  Scientists reexamined the cosmic microwave background using the ACT.   Astronomers were able to observe the CMB on a smaller scale than ever, so they were able to see many more details and irregularities that told of what happened in the early universe and how far back those phenomena occurred. 

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-   The age of the universe an age of 13,800,000,000 years. 

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-  November 8, 2022            Age of the Universe                   3736                                                                                                                                

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--------------------- ---  Wednesday, November 9, 2022  ---------------------------






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