New theory: Universe isn't expanding... it's just getting fat

Conventional thinking says the Universe has been expanding ever since the Big Bang. But theoretical astrophysicist Christof Wetterich says it's not expanding at all. It’s just that the mass of all the particles within it is steadily increasing.

We think the Universe is expanding because all the galaxies within it are pushing away from one another. Scientists see this as the redshift — a kind of doppler effect that happens when atoms emit or absorb light.

We see these frequencies as appearing in the red, an indication that mass is moving away from us. Galaxies exhibit this redshift, which is why scientists say the Universe is expanding.

However, Wetterich, who works out of the University of Heidelberg in Germany, says the characteristic light emitted by atoms are also governed by the masses of the atoms’ elementary particles, particularly their electrons. He says his theory is useful for thinking about different cosmological models. And indeed, it may offer some fresh insights into the spooky dark energy that's apparently pushing the Universe outwards at an accelerating rate.

Such an interpretation could help physicists to understand problematic issues such as the so-called singularity present at the Big Bang, he said. "I think it's fascinating to explore this alternative representation. His treatment seems rigorous enough to be entertained," Journal Nature quoted Hongsheng Zhao, a cosmologist at the University of St Andrews, UK, as saying.

In the 1920s, astronomers including Georges Lemaitre and Edwin Hubble found that most galaxies exhibit a redshift -- and that the redshift was greater for more distant galaxies. From these observations, they deduced that the Universe must be expanding.

Read more about the theory here or about the entire study — which has not yet been peer reviewed — at arXiv: “A Universe without expansion.”