Friday, June 30, 2023

4070 - EUCLID SPACE TELESCOPE

 

-    4070  -  EUCLID  SPACE  TELESCOPE  -  observing the expansion of the Universe.  5 billion years after the Big Bang, the dynamics of the universe changed: instead of slowing down further, the expansion of the universe is still accelerating today. This “dark energy” now dominates the expansion.

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---------------------   4070   -    EUCLID  SPACE  TELESCOPE

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-   Tomorrow,1 July, 2023,  the Euclid space telescope will start its journey into outer space on an important mission to seek further clues about the origin of the universe.

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-    The visible matter known to researchers is actually only around 5% of the universe; 95% of the universe is a proverbial black box. Two invisible factors, dark matter and dark energy,  influence the arrangement of objects in space and the expansion of the universe.  Remember matter and energy are two forms of the same thing.

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-   The Euclid space telescope is now prepared to shed light on the darkness.  It will start its mission to record, in a 3D map, the large-scale structure of galaxies up to 10 billion light years away from Earth. Researchers hope that this unique recording of the cosmic web will reveal more about the nature of dark matter and dark energy as well as the laws of gravity.

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-   Dark matter is matter that does not emit, absorb or reflect light.   Because it is invisible, it's difficult for researchers to study it. But it seems clear that there must be something else there. The observed arrangement of galaxies cannot be explained by general relativity, unless there is more mass than we can see.

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-    The only way for us to study dark matter is through its interaction with the gravitational force. On board “Euclid”  is an instrument called a VISible (VIS), which can image galaxies with tremendous precision. From the pictures, astronomers will measure how distorted the galaxies appear.

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-    This distortion takes place because of an effect called “gravitational lensing”: mass that lies between the telescope and the observed galaxy deflects the light like a magnifying glass, making the galaxy behind it appear distorted.  This effect will give us information about how much dark matter lies between Euclid and the observed galaxy.

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-   Since 1998, researchers have been working on another invisible phenomenon that cannot be explained by Einstein's theory of general relativity. Based on measurements of exploding, extremely bright stars (supernovae), two research groups have found that the expansion of the universe is not slowing down due to gravity, as previously assumed, but accelerating.  This acceleration started about 5 billion years ago.

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-    The simplest description researchers currently have for dark energy causing this accelerstion is the “cosmological constant”: it states that the density of dark energy does not change over the entire evolution of the cosmos. As Euclid looks back to the beginnings of the universe 10 billion years ago by observing very distant galaxies, researchers can investigate whether dark energy has indeed not changed over time.

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-   The near-infrared spectrometer and photometer (NISP), with which the researchers can evaluate a phenomenon called the “red shift”. Similar to the “Doppler effect” of light, galaxies moving away from us appear "redder" because the received wavelength gets stretched.  The farther a galaxy is away from us, the faster it is moving away from Earth.  From the red shift astronomers can deduce the distance to the galaxy and obtain information about the expansion of the universe.

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-   Has the density of dark energy changed in the course of the evolution of the universe?

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-   Euclid could also provide crucial clues about Einstein's theory of general relativity. The laws of gravity only work at huge scales if we introduce these “dark components" . But, it is also possible that on a cosmic scale, general relativity is not yet correct.  Researchers have developed many complex models of modified theories of gravity,

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-     A simulation by the UZH computer maps all the galaxies that Euclid could potentially observe. Among other things, it is used to test how well the analysis tools deal with immense amounts of data. Astrophysics are running through different dark matter scenarios and investigating what effects they have on cosmological observations.

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-     Currently, the best proven model for the origin of the universe is the “Big Bang theory”. It describes the development of the universe after the Big Bang 13.7 billion years ago when matter, space and time came into being.  The Big Bang is not necessarily the beginning of the universe, but a point in time before which we cannot say anything scientifically because it is not accessible to our observation.

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-    In the first phase after the Big Bang, the universe expanded rapidly. At this point, it consisted of an almost homogeneous plasma of elementary particles. Only when the universe cooled down more and more did the first atoms form and photons were able to split off. This was followed by the so-called "Dark Ages," in which there were still no galaxies and no visible light sources.

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-   About 200 million years after the Big Bang, stars and galaxies began to form. Under the force of gravity, the individual galaxies increasingly formed a large-scale structure that resembles a network of nodes and connections, it is therefore also called the “cosmic web”. In between there are almost matterless regions, known as voids.

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-    The phase when the cosmic web formed is called the “matter-dominated phase” of the universe, because it was driven by gravity and dark matter. However, 5 billion years after the Big Bang, the dynamics of the universe changed: instead of slowing down further, the expansion of the universe is still accelerating today. The researchers explain this by the fact that “dark energy” now dominates the expansion.

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June 29,  2023          EUCLID  SPACE  TELESCOPE                 4070

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--------------------- ---  Friday, June 30, 2023  ---------------------------------

 

 

 

 

 

           

 

 

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