“However, there is a price to pay: we need a partner anti-universe whose time flow is oppositely related to our universe.” This isn’t the first time that such an idea has been put forward.

Of this enormous slice of the universe's matter and energy budget, dark energy — the placeholder name for the force causing the expansion of the universe to accelerate — accounts for around 70%.

The new model forgoes the need for either dark matter or dark energy as explanations for the universe's acceleration and how structures like galaxies are generated. The researcher's work builds on ...

These place the tightest constraints on the history of expansion throughout the 13.8 billion-year history of the cosmos, but they also leave breathing room for more complex models of the universe.