A Stranger Thing May Explain The Universe : ScienceAlert

Perhaps there is no mysterious ‘dark’ force accelerating the expansion of the Universe after all. Reality can be even stranger – bubbles in space where time passes at very different rates.

The passage of time is not as constant as our experience of it suggests. Areas of higher gravity experience a slower flow of time compared to areas where gravity is weaker, a fact that has some major implications for how we compare rates of cosmic expansion. according to a newly developed model called. timescape cosmology.

Differences in how fast time passes in different regions of the Universe can add up to billions of years, giving some areas more time to expand than others. When we look at distant objects through these time-changing bubbles, it creates the illusion that the expansion of the Universe is accelerating.

Two new studies analyzed more than 1,500 supernovae to test how plausible the concept might be – and found that the timescape model may be a better fit for the observations than our best model. today.

the standard model of cosmology does a good job of explaining the Universe – as long as we fudge the numbers a bit. There didn’t seem to be enough mass to account for the gravitational effects we observed, so we invented an invisible placeholder called black matter.

There also seems to be a strange force that restrains gravity, which drives the cosmos to expand at rapid rates. We still don’t know what it is, so in the same spirit we dubbed it dark energy. All of this combines, along with ordinary matter, to form what we call the lambda cold dark matter (ΛCDM) model.

The problem is that this model uses a simplified equation that assumes the entire Universe is smooth, and expanding at the same speed everywhere. But it is far from smooth there: we see a big cosmic webcriss-crossed by filaments of galaxies separated by vast voids vaster than we can comprehend.

Timescape cosmology accounts for that ‘lumpiness’. More matter means stronger gravity, which means slower time – in fact, an atomic clock located in a galaxy would be ticking. up to a third slow than the same clock as half empty.

If you study that over the length of the Universe, billions of years more have passed in the voids than in the dense areas of matter. A puzzling implication of that is that it no longer makes sense to say that the Universe has a unified age of 13.8 billion years. Instead, different regions have different ages.

And because more time has passed in the voids, further cosmological expansion has occurred there. So, if you look at an object on the far side of a vacuum, it will appear to be moving away from you faster than an object on this side of the vacuum. Over time, these voids will take up a larger proportion of the Universe, creating the illusion of a rapid expansion, without necessarily creating any dark energy.

In 2017, astronomers from the University of Canterbury in New Zealand tested timescape cosmology against observations, and found it to be slightly better than ΛCDM to explain the cosmic expansion. More data is needed.

So for new studies, an astronomy team from the University of Canterbury and the German University of Heidelberg collected and analyzed that additional data in the form of a catalog of 1,535 Type Ia supernovae. These explosions glow with predictable brightness each time, so shifting their light can reliably reveal distance, speed and direction of movement. As such, they are often referred to as ‘standard candles.’

This time, the astronomers say they found “very strong evidence in favor of the ΛCDM timescape.” This suggests a potential need to rethink the foundations of cosmology.

“Dark energy is a misidentification of differences in the kinetic energy of expansion, which is not uniform in a Universe as lumpy as the one we live in,” said David Wiltshirea physicist at the University of Canterbury.

“The research provides compelling evidence that may resolve some key questions around the quirks of our expanding cosmos. With new data, the Universe’s greatest mystery may be solved by the end of the decade.”

The two study published in the journal Monthly Notices of the Royal Astronomical Society.