A new study casts doubt on the composition of nearly 70% of our world. According to these new simulations, dark matter with "magnetic capabilities" could actually be driving the evolution of the Universe.
At the end of the 1920s, astronomer Edwin Hubble made a discovery that revolutionized astronomy:all galaxies are moving away from us, but also from each other. In other words, the Universe is expanding . Then imagine a chocolate chip muffin slowly baking inside your oven. As the muffin puffs up, the distance between each nugget only gets longer.
Another stunning discovery. In the 1990s, researchers demonstrated that the escape velocity of galaxies from the Milky Way increases with time. In other words:we therefore observe an expansion of the Universe, but also an acceleration of this expansion .
To explain these observations, a repulsive force opposed to gravity was then imagined. This entity, astronomers have dubbed it "dark energy". And according to calculations, it constitutes about 68% of the total energy density of the Universe . Only here, just like dark matter, we can only deduce its presence by its indirect effects on matter. In other words, to date we have no real proof of its existence.
Also, given the importance of understanding its underlying physics, it is relevant to study alternative designs. As part of a new study, researchers from the University of Copenhagen asked themselves the following questions:what if, in reality, dark energy does not exist? What if, instead, this acceleration of the expansion of the Universe was the work... of dark matter?
" We don't know much about dark matter, other than that they are heavy, slow-moving particles. But then we wondered - what if dark matter had a quality analogous to magnetism, what would happen? » , explains Steen Harle Hansen, the main author of this work.
This question therefore served as the basis for the development of a new computer model. Crudely, the researchers took dark energy out of the equation and added a few more properties to dark matter. They then assessed the behavior of the Universe. And, somewhat surprisingly, dark matter with magnetic capabilities seemed to have exactly the same effect on the expansion of the cosmos as dark energy.
" If what we discovered is accurate, it would upset our belief that what we thought was nearly 70% of the Universe doesn't actually exist " , emphasizes the researcher.
Of course, these conclusions will need to be verified with better models that take more factors into consideration. "Honestly, our discovery might just be a coincidence" , concedes Steen Harle Hansen.
" But if not, it's really amazing. This would change our understanding of the composition of the Universe. From what we know now, the idea of dark matter with some type of magnetic force and dark energy is equally wild. Only more detailed observations will determine which of these models is more realistic ” .
In the meantime, the principle of dark energy is still being considered, and research is continuing to try to better understand it. A new instrument, called DESI, has been studying the movements of millions of galaxies for several months with the aim of shedding light on this entity.
Recall that the ESA's Euclid mission, currently in the test phase, also promises to shed light on this cosmic mystery. To do this, the mission will rely on a 1.2-meter-diameter telescope with two instruments:a visible-light (VIS) imager and a specialized near-infrared spectro-imager (NISP). Its launch is scheduled for 2022.
Thanks to these two instruments, we could therefore have all the answers to these two fundamental questions:where do we come from? And where are we going?
