Cape Canaveral.- The European Euclid mission will observe billions of galaxies for six years to create the largest and most accurate 3D map of the universe. It will look as far away, as far as 10 billion light-years away, that its result is unknown: the most exciting finding is the one that is not expected.
The two-ton, 15-foot-tall spacecraft will blast off on a SpaceX Falcon 9 rocket from Cape Canaveral, Florida, on Saturday. In addition to the documentation of the European Space Agency (ESA), Guadalupe Cañas Herrera, theoretical physicist and cosmology researcher at this organization, explains to EFE some of the main objectives of the mission.
What is Euclid’s most important task?
Mapping the last 10 billion years of cosmic history across more than a third of the sky, from “cosmic noon,” when most stars formed, to the present day.
This “look” back into the past will make it possible to collect information about the shapes, positions and distances of galaxies. Everything will be brought together in a three-dimensional atlas that will be shared with the scientific community.ica.
Why so many galaxies?
It is needed to build a detailed map of the distribution of matter in the universe and to infer the speed at which objects are receding from each other.
Only such a comprehensive atlas of the structure and history of the cosmos on a large scale will help reveal hitherto unknown features of dark matter and energy, and complete our understanding of gravity.
What is known about dark matter?
In the universe, normal matter is that which integrates planets, galaxies or stars and represents 5%; the rest is in the form of dark matter (around 25%) and dark energy (70%), different components that cosmology is still trying to clarify.
Dark matter, whose existence was discovered more than half a century ago, does not emit light but exerts a gravitational attraction. It is fundamental to understanding the way in which the universe is grouped together, from the great structures of voids and superclusters of galaxies to the Milky Way.
Although invisible to us, its presence distorts light from distant galaxies. This effect is called “gravitational lensing” and can be observed by Euclid, thus revealing the distribution of dark matter throughout the universe.
The hypothesis is that most of the darkness is made up of cold particles, which are heavy and move relatively slowly. But it is highly probable that a part of it also consists of light (hot) particles moving at a speed close to light.
The question remains how much of this dark matter is hot, if any, and what particles make it up; neutrinos are candidates, but there are still many doubts that fly over.
What is dark energy?
It is one of the important questions of modern cosmology. This would be producing the accelerated expansion of the universe.
At first it was believed that this expansion was the product of the “big bang” with which the entire universe originated; It was accepted that at some point this expansion would stop due to the opposite effect of the force of gravity that binds matter together, but this is not the case.
There is something that somehow creates more and more space between galaxies and this is dark energy, of which neither its source, nor its physics, nor how it works is known.
Euclid will provide information on how the rate of expansion of the universe has changed over time and whether this expansion is the same in all directions.
Otherwise, what is known as the “cosmological principle” would be violated, according to which the universe, when observed on a large enough scale, looks the same in all directions (isotropy) and from all places ( homogeneity).
This fundamental rule forms the basis of almost all models and analyzes used in cosmology.
Was Einstein wrong?
Matter and dark energy are related to gravity. The best theory that exists today to describe it it is Albert Einstein’s general relativity, but this has not been precisely tested at great distances, such as those that Euclid will explore.
It has never gone that far, so one possibility is that the standard model of cosmology, based on this theory, works, but it could also be that alternative equations fit better. If so, they would have to pass the “test” of the Solar System, explain as well as the theory of relativity what happens in our planetary system.
Guadalupe Cañas Herrera acknowledges being a dreamer, like all theoretical physicists. “I would love to see Euclid’s data overthrow the standard cosmological model, because it would open the door to exploring other theories that could tell us a little bit more about the nature of dark energy and matter, and the origin of the universe.”
«But the model we have is very robust, so it would not be enough for Euclid to tell us that it is not the best one that explains the data, we would have to verify it experimentally with other alternative observations. That’s science.”
