95% of the universe is made up of something we don't know

Understand how it all started. And that's the goal Dark Energy Survey (DES)This “allows us to test whether the accelerating expansion of the universe, which began 6 billion years ago, is consistent with our current cosmological model,” he explains. general One of its participants is a cosmologist Martin Rodriguez Monroy.

It refers to the largest study of its kind to date on the origin of the universe. He analyzed data from more than… 16 million galaxies They were collected between 2013 and 2019, from a sample of 150 million galaxies. Your search results They just met This week, it is the result of a International cooperation With the participation of more than 400 scientists from seven countries, based on Chicago Fermilab.

Among them is Martin Rodriguez and his colleagues Institute of Theoretical Physics (UAM-CSIC) and three other Spanish centres: the Center for Research on Energy, Environment and Technology (CIEMAT), the Institute of Sciences in Language (ICE.CSIC), and the Institute for Physics of Alternative Energies (IFAE).

What we have believed until now is called into question

Their findings are as exciting as they are a challenge to established science: it is possible that this is the case Standard cosmological model Which describes the behavior of the universe does not always occur as expected.

DES astrophysicists measured galaxies at different distances to compare whether the theory could apply to all of them equally. “With the data given at a given point—equivalent to the age of the universe, calculated at its distance— We should be able to predict the data at another point “Before or after,” says Rodriguez-Monroy.

However, this is not the case. It turns out that there is a slight inconsistency between the data collected by Planck satellite 2018 Which depicts the early universe, in the first moments of its life – some 400,000 years After the Big Bang, and DES data, which depicts space several million years later.

“Our results differ by 4% from what Planck predicted. Moreover, we know our measurements with 95% accuracy. That is, there “There is only a 5% chance that the 4% difference is just a coincidence.”“, points out the researcher.

Evidence that the current theory is not completely complete. “For example, dark energy may not be vacuum energy, and its density may change as the universe expands, or even… “The space can be a little curved.”an adventure by the Spanish astrophysicist Anna Buridoneone of the coordinators of this analysis.

However, Rodriguez-Monroy recommends caution: “It cannot be said that the established model has been broken, but the possibility exists.” “There is another explanation that may be relevant to some Systematic error“It has to do with biases in the observations – for example, due to the area observed or the observation point chosen –,” he tells us.

Dark energy is elusive

To capture the data, DES used the so-called Ultra-sensitive Dark Energy Camera (DECam), with a resolution of 500 megapixels, mounted on the Víctor M. Blanco telescope, in Cerro Tololo Inter-American Observatoryin Chile.

After analyzing all the material collected, what they noticed were “small discrepancies that could imply that dark energy changes over time,” Rodriguez-Monroy tells us. that it Dark energy may not conform to the cosmological constant As he thought.

Refers to that unknown entity that occupies 70% of the universe“But we don't know what it is,” he admits. Currently, there are various alternative hypotheses for the cosmological constant, which have not yet left the field of speculation.

“We can say that we call dark energy what causes Accelerated expansion Universe. Whatever”.

Another element that escapes our current understanding has the same moniker, although it is not related to the previous name: dark matter, which occupies 25% of the universe. “We don't know what particle is behind it, if it is a particle – it could be special black holes. The only thing we know about it is that it is a type of matter that… It has mass, but it does not interact with light like ordinary matter as we know it. “It only reacts to gravity,” says the scientist.

What is the benefit of devoting all this effort to achieving both? If there is a fundamental science par excellence, perhaps it is this one, which is determined to uncover the origin of the world's existence. Rodriguez Monroy who defends Knowledge for knowledge's sakeHe believes that “you first have to know how things work before you can see their applications.”

Moreover, it is reminiscent of Faraday's (1791-1867) statement when he was asked the same thing about the first studies of electricity: “I do not know, but certainly Someday they will tax this“.