Do you believe in ghosts? Ghosts can move furniture in our house without us seeing them!
Therefore, we learn about the existence of ghosts only indirectly, without knowing what they are, without having seen them, without being able to predict when they will come again… We can only say that MAYBE they exist because they move furniture. The only thing we perceive is the moved furniture!
Exactly, it’s the same with dark matter and dark energy in the universe.
The composition of the universe.
The majority of the pie is taken up by dark energy (blue color) and dark matter (black color). Hydrogen and helium (blue color) make up a very small percentage (only about 4%). These two elements are abundant in the universe. As shown in the diagram, stars, neutrinos, and heavy elements make up only 1%, a tiny portion of the pie. Dark energy and dark matter are currently (in 2022) the great mysteries of the universe. They do not emit any radiation and do not interact with anything.
The European Space Agency (ESA) has given final approval for the construction of the Euclid space telescope. Euclid will seek answers to these two great mysteries of modern cosmology.
Astronomers and cosmologists today believe that the visible matter in space – from stars to nebulae and galaxies – accounts for approximately only 5% of the total energy-matter content of the Universe (according to Einstein, mass and energy are equivalent). Approximately 25% of the Universe is composed of “dark matter” – a mysterious form of matter that does not emit, absorb, or reflect electromagnetic radiation. Dark matter is literally invisible, and its composition remains completely unknown. However, its presence can be detected through its gravitational effects on normal matter.
The remaining 70% of the Universe corresponds to an even more mysterious dark energy. The first hints of its existence came in 1998 when astronomers realized that the expansion of the Universe was accelerating instead of slowing down due to the gravitational pull of celestial bodies. The most likely explanation, according to physicists, is that there is an as-yet-unknown force in the Universe called dark energy, which acts in opposition to gravity and forces spacetime to stretch at an ever-increasing rate.
The Euclid telescope will investigate the acceleration of the Universe over the last 10 billion years (up to z=2). It seems necessary to clarify whether the Universe is expanding or contracting. The new Euclid space telescope will help answer this question.
The launch date has currently been scheduled for sometime between July and September 2023.
Another exciting launch to look forward to in 2023! Let’s hope it goes well!