The known universe began with the Big Bang, and stars and galaxies gradually formed. That is what we have always believed, which corresponds to the current cosmological model, but it seems that it is not entirely true.
If we look with a super-powerful telescope to the furthest reaches of our planet, we can get to see how the galaxies were shortly after the Big Bang, and most of the time we have always seen young galaxies, not very massive, with young stars… all just recently. born. Until now.
The James Webb Space Telescope has discovered six very large galaxies in the very old universe, which has surprised scientists. These galaxies formed between 500 and 800 million years after the Big Bang, which is very early in the history of the universe. Scientists expected to find small, young galaxies, but these galaxies are very mature, like the Milky Way.
How is it possible for the telescope to see the past of the universe?
Remember that light travels at a limited speed, 299,792.458 kilometers per second, so all we see at great distances is the state it was in billions of years ago. The current state of those galaxies is still being transmitted through space, it will take billions of years to reach earth.
The surprising discovery
Data from the telescope show that these galaxies have much more mass than was thought possible at that early time in the universe. This means that the formation of massive galaxies began much earlier than previously believed, which calls into question what was known about the origin of the universe.
The discovery is important because it means that scientists will have to change their understanding of the universe. Until now, it was believed that galaxies began as small clouds of stars and dust that gradually grew larger over time. But these massive galaxies show that something different happened in the early universe.
How it was detected
The James Webb Telescope uses infrared detection instruments to detect the light emitted by the oldest galaxies. This allows scientists to see back in time, near the beginning of the universe. It’s like looking at an old picture of the universe and seeing what was happening at the time.
The scientists now want to confirm their discovery by taking a spectrum image of the massive galaxies. This will give them more information about how big they are and how far away they are. It will also allow them to know what gases and other elements make up galaxies.
How the cosmological model can change
How this might fit into a new cosmological model is already being discussed. There is one, known as the cosmic inflation theory.
The theory of inflation postulates that during the first moments after the Big Bang, the universe underwent a rapid exponential expansion that occurred due to the presence of a field (or particle) called inflaton. This expansion would have solved several theoretical problems of the standard cosmological model, such as the flatness of the universe and the inhomogeneity and isotropy.
There will be a lot of discussion about the matter, but it is clear that James Webb will keep astronomers busy for a long time to come.
You have more information at nature.com
