- 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.
-
---------------------
4070 - EUCLID
SPACE TELESCOPE
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- Has the density of
dark energy changed in the course of the evolution of the universe?
-
- 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,
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
June 29, 2023 EUCLID SPACE
TELESCOPE
4070
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Friday, June 30, 2023
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