Scientists from the large international consortium Dark Energy Survey (DES) have presented the largest and most comprehensive “map” of dark matter in the universe. Dark matter is an invisible substance that is estimated to make up about 25% of the total matter in the universe, compared to 5% of visible matter and 70% of dark energy. Remarkably, the distribution of dark matter appears to be such that, according to some scientists, it casts doubt on the correctness of Albert Einstein’s general theory of relativity.
400 researchers from seven countries used the Dark Energy Camera – one of the world's most powerful with a resolution of 570 megapixels, to analyze – with the help of artificial intelligence (AI) – 226 million galaxies, thus revealing a "patchwork" with huge completely dark empty regions of very low matter density (where gravity can behave differently) and brighter regions (where dark and visible matter are concentrated).
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Invisible dark matter affects visible matter, distorting the light that reaches Earth from distant stars and galaxies. The greater the distortion, the greater the concentration of dark matter in a galaxy or other region of the universe.
Why is this new "map" said to be a "problem for physics"?
Dr Niall Jeffrey, a researcher at the Ecole Normale Superieure in Paris and University College London (UCL), told the BBC that the new map was “a real problem for physics” because it showed that “maybe Einstein was wrong”. He added that “you might think this is a bad thing, that maybe physics is collapsing. But for a physicist it is incredibly exciting. It means we can discover something really new about what the Universe is like.”
Additionally, Carlos Frenk, a professor at Britain's Durham University who helped develop the modern cosmological theory based on Einstein's work, said he had mixed feelings about the new findings. Specifically, he said: "I've spent my life working on this theory and my heart says I don't want to see it fall apart. But my brain says the measurements are correct and so we need to explore the possibility of new physics. This is something that makes me very nervous and scared, because we are entering completely unknown territory and who knows what we are going to find."
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According to Jeffrey, the map clearly shows that galaxies – including our own – are part of a larger invisible structure due to dark matter. Until now, scientists had formed an accurate idea of the distribution of matter, starting 400,000 years before the Big Bang, thanks to the Planck orbiting telescope , which measured the remnants of the cosmic microwave background radiation, also known as the "twilight of creation".
Combining Planck's data with Einstein's theories, astronomers like Frenk have developed a model that predicts what the distribution of matter should have been like over the past 13.8 billion years. The consortium's official announcement says the new "map" is consistent with theoretical predictions.
Some researchers, however, pointed out that, based on the new observations and the "map", there is a slight discrepancy, as matter actually appears to be slightly more evenly distributed than expected based on Einstein and the predictions of the dominant cosmological model.
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"We may have discovered something really fundamental about the fabric of the universe. The current theory is based on very imperfect pillars of sand. And what we may be seeing now is the collapse of one of those pillars," Frenk said.
The question that arises is whether Einstein's theory is perfect
Several scientists, such as Professor Ofer Lahav of UCL, have refused to rule out Einstein, at least for now. Lahav pointed out that “the big question is whether Einstein’s theory is perfect. It seems to pass every test, but with a few deviations here and there. Perhaps the astrophysics of galaxies needs some minor tweaking. In the history of cosmology there are examples where problems were solved, as well as examples where the way of thinking changed. It will be interesting to see whether the new ‘intensity’ in cosmology will lead to a new revolutionary scientific change.
The map, which will be published in the Monthly Notices of the Royal Astronomical Society, brings us closer to understanding what the universe is made of and how it has evolved.
