- The way scientists confirm the existence of dark matter is by studying the pathways of light traveling to Earth from other galaxies.
- After analyzing the shapes, structures, and locations of matter around the map, the scientists then compared them to measurements that the Standard Model of Cosmology
- While the distribution of matter observed by the DES team was largely consistent with what the Standard Model predicted, it was shifted by a few percent, suggesting that there may be an aspect of the universe that the standard model did not take into account.
One of the most enigmatic concepts in astrophysics is that of dark matter. We have never seen it and barely have an understanding of its nature, but we are sure it exists.
How do we know this? Well, the mysterious substance makes up about 27% of the universe, and although it is invisible, exerts a gravitational force on objects so powerful that it is able to mesh entire galaxies into massive superaggregates.
We’ve known this for decades, but it’s only now that scientists have been able to create the largest ever map of dark matter. And the results, it seems, may force us to overturn one of the most reliable theories ever formulated – Einstein’s theory of relativity.
The way scientists confirm the existence of dark matter is by studying the pathways of light traveling to Earth from other galaxies. If the light has been distorted, it means that there is some kind of matter in the foreground that bends the light as it moves towards us. This phenomenon is known as the gravitational lens, and measuring the amount of light that has been bent allows scientists to calculate the density of the matter making the bend.
An international team of scientists mapping dark matter in the universe as part of the Dark Energy Survey (DES) project has now created a map that has studied about 5,000 square degrees – nearly one-eighth of the sky – to provide some of the most accurate measurements of the composition and growth of the 400,000 year old universe since the Big Bang to date.
The results are the result of a three-year data collection – scientists scanned 226 million galaxies in 345 nights – and offer a map of the universe whose scale has never been managed before.
Using the map, scientists were able to distinguish matter like galaxies visible on the electromagnetic spectrum from other less dense black spots called cosmic voids. It is these voids in particular that have captured the attention of researchers.
Dr Niall Jeffrey, from University College London and Ecole Normale Supérieure Paris, and one of the co-leaders of the project said: “It shows us new parts of the universe that we never had before. seen before. We can really see this cosmic web structure, including these huge structures called cosmic voids, which are very low density regions of the universe where there are very few galaxies and less matter.
After analyzing the shapes, structures, and locations of matter around the map, the scientists then compared this to measurements that the Standard Model of cosmology – which relies heavily on Einstein’s general theory of relativity describing the gravity – predicted.
And while the distribution of matter observed by the DES team was largely consistent with what the Standard Model predicted, it was shifted by a few percent, suggesting that there might be an aspect of the universe that the standard model, which has been in use for decades and served astrophysicists so reliably, did not take into account. “If you look out into the universe, the question isn’t as lumpy as you might expect – there are hints that it’s smoother,” Dr. Jeffrey said.
While the measurements and calculations performed by the DES team are, indeed, accurate, the results have extremely important implications and may force astrophysicists to revise some fundamental assumptions about the composition of the universe. “It may seem like a relatively small thing, but if these clues are true, it may mean that there is something wrong with Einstein’s general theory of relativity, one of the great pillars of physics. Added Dr Jeffrey.