Tuesday , October 19 2021

The universe may be a billion years younger than we thought. Scientists are struggling to figure out why.


Per Corey S. Powell

We all lose track of time at one point or another, but astronomers really go all-in. Recent studies show that they may have overestimated the universe's age by more than a billion years – a startling realization that is forcing them to rethink parts of the scientific history of how we got from the Big Bang to the present.

Time lost is especially vexatious because, in a universe full of mysteries, its age has been seen as one of the few certainties. By 2013, detailed measurements of cosmic radiation from the European Planck Space Telescope appeared to have produced the final answer: 13.8 billion years. All that is left to do is verify this number using independent observations of bright stars in other galaxies.

Then came an unexpected turn of events.

Some teams, including one led by Nobel laureate Adam Riess of the Space Telescope Science Institute in Baltimore, decided to make those observations. Instead of confirming Planck's measures, they began to obtain a distinctly different result.

"It's getting to the point where we say," Wait a second, we're not going through this test – we're failing the test! ", Says Riess, co-author of a new article on the research to be published in the Journal Astrophysicist.

He estimates that its results, taken at face value, indicate a universe that is only 12.5 billion to 13 billion years old.

Studies of stellar clusters in a neighboring galaxy add evidence that the universe is younger and expands faster than expected.Institute of Science of the Space Telescope of Public Disclosure / NASA, ESA, A. Reiss (STScI / JHU)

At first, the common assumption was that Riess and the other observers of the galaxy had made a mistake. But as observations continued, the results did not move. The reanalysis of the Planck data also showed no problem.

If all numbers are correct, the problem must be deeper. It must be in our interpretation of these numbers – that is, in our fundamental models of how the universe works. "The discrepancy suggests that there is something in the cosmological model that we are not fully understanding," says Riess. What this thing could be, no one knows.

Discovery of the dawn of time

The current discrepancy dates back to 1929 when astronomer Edwin Hubble discovered that galaxies are fleeing from Earth in all directions. More shocking, Hubble discovered that the further away the galaxies are, the faster they are moving away. This pattern means that they are all running away from each other as well. "The only way this is true is if space is expanding," says Riess.

If the idea of ​​an expanding universe seems bizarre to you, welcome to the club.

"It's also bizarre to me too," says Riess. "But that's what all the data shows, and that's what our theory predicts." Even Hubble did not fully accept the implications of his own work.

An expanding universe implies that the universe has a definite age, because you can remake the action back to a time when everything in the cosmos was heaped up in an extremely dense and hot state: what we call the Big Bang.

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