We’ve just realised our understanding of the universe might be wrong

We’ve thought this one thing about the universe for 100 years (Picture: Getty/Metro) The universe, that 13.8billion-year-old thing we call home, is a weird place. But one thing that has made sense to scientists for the better part of a century is the belief that the cosmos is surprisingly uniform. This is known as the cosmological principle, or the idea that if you took a step back – a very big step back – and took a photo of the universe, it would look smooth and blurry, like you forgot to wear glasses. A paper published in the journal Nature, however, argues this might not be the case. Rather, things look different from every direction you look at from a large scale, and the galaxies line up almost into patterns. While this might not sound like a big deal, if proven, this would change the math that explains how existence works. Researchers figured this out by looking at the largest map of the known universe observed by the Dark Energy Spectroscopic Instrument. A slice of the largest map of the universe (Picture: Collaboration/DOE/KPNO/NOIR) They compared this to simulations of how dark matter – the mysterious something holding galaxies together – is distributed in a uniform cosmos. Researchers checked if there was any kind of pattern when comparing them. ‘Essentially, we asked what the probability of finding a galaxy at a given distance with respect to another and along a given direction,’ study co-author Marco Galoppo tells Metro. Galoppo, of the University of Canterbury in New Zealand, should have been left cooing at how homogeneous (the same everywhere) and isotropic (the same in all directions) the universe is. It should begin to smooth out when observed at scales of about 100 megaparsecs – roughly 300 million light-years – from every direction. Instead, they saw a stringy, bumpy web of galaxies and voids even when approaching a whopping one gigaparsec, which is three billion light-years. Follow Metro on WhatsApp to be the first to get all the latest news Follow us to receive the latest news updates from Metro (Picture: Getty Images) Metro’s on Whatsapp! Join our community for breaking news and juicy stories. The lack of uniformity, called anisotropy, was ‘stronger’ than expected. ‘Any local structures – galaxies, clusters, filaments – are expected to “wash out” at large scales,’ Galoppo says. ‘Our results suggest that this may not be entirely true: we see directional patterns that are stronger than expected, implying that the universe may not reach perfect isotropy even on the largest observable scales. ‘In other words, the cosmic web may leave an imprint on the overall structure and expansion of the universe in a way that does not fully average out.’ The findings don’t mean the universe has a preferred axis or direction and they need to be replicated using larger datasets. So, the universe isn’t uniform – so what? Cosmologists, scientists who study the origin, history and evolution of the universe, expect to get things wrong. But to be wrong about cosmological principle would be a rather big deal, researchers not involved in the study told Metro. Around 80% of the volume of the cosmos is made of nothing, called cosmic voids. Some have dim galaxies inside them, like a celestial oasis, or are crammed with cosmic energies we struggle to explain. One thing that explains this empty space is the recipe to make a universe: 5% ordinary matter, 27% dark matter and 68% dark energy, the other invisible something pushing our universe to expand ever faster. The cosmos should appear smooth and uniform when viewed at a large distance (Picture: ESA/Webb/NASA/CSA/JADES Coll/Reuters) If the universe is not uniform but more like a bowl of spaghetti, cosmologists may have to accept that dark energy isn’t that important. Kathy Romer, a professor in astrophysics at the University of Sussex, says that Galoppo’s paper is undoubtedly controversial. That’s the point. ‘Papers such as these are valuable in that they challenge orthodox thinking: as scientists we should always be alert to the “Emperor’s new clothes” trap,’ she says. ‘Without doubt, there is something funny going on in the local-ish universe (mapped by galaxies), because there is an emerging mismatch with the distant universe (mapped by the cosmic microwave background). ‘This paper is part of a global effort to question every observation and theoretical assumption to understand that mismatch.’ Romer stresses that Nature has a ‘rigorous’ review process and that the bar to prove things in science is high. Think of how a pixelated photo would look smooth from faraway (Picture: NOIRLab) ‘We would all (where “all” is the observational cosmology community of 5,000 people) love this mismatch to be genuinely new physics because for us that is like winning the World Cup,’ she adds. ‘But my personal opinion, this study is part of the qualifying stages, not the final 32.’ Konstantinos Migkas, a Dutch astrophysicist, says the findings follow similar studies published this year. And his own, too, which was referenced by Galoppo. Migkas and his colleagues also found signs of anisotropy, adding further questions to why there is something in some places but not elsewhere. ‘This does not mean that anything has been concluded yet, but it is natural that assumptions built into our standard model will be tested more sharply as data quality and volume improve,’ Migkas tells Metro. Not everyone is swayed. ‘It’s not a big deal for the world of cosmology because this paper is wrong,’ says Seshadri Nadathur, a professor in cosmology at the University of Portsmouth. Nadathur suggested the patterns could be chalked up to galaxy bias, where galaxies seem to clump together, which distorts measurements. ‘The reason we believe the universe is uniform is because observations of the real universe suggest it is true, and there has never been any convincing evidence otherwise,’ he adds. ‘There are occasional claims of some discovery contradicting this picture, but they are always flawed.’ Get in touch with our news team by emailing us at webnews@metro.co.uk. For more stories like this, check our news page. 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