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New theory says the Universe isn't expanding — it's just getting fat

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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.

Top Image: T. Piner.

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.


But 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.

Writing in Nature News, Jon Cartwright explains:

If an atom were to grow in mass, the photons it emits would become more energetic. Because higher energies correspond to higher frequencies, the emission and absorption frequencies would move towards the blue part of the spectrum. Conversely, if the particles were to become lighter, the frequencies would become redshifted.

Because the speed of light is finite, when we look at distant galaxies we are looking backwards in time — seeing them as they would have been when they emitted the light that we observe. If all masses were once lower, and had been constantly increasing, the colours of old galaxies would look redshifted in comparison to current frequencies, and the amount of redshift would be proportionate to their distances from Earth. Thus, the redshift would make galaxies seem to be receding even if they were not.

Work through the maths in this alternative interpretation of redshift, and all of cosmology looks very different. The Universe still expands rapidly during a short-lived period known as inflation. But prior to inflation, according to Wetterich, the Big Bang no longer contains a 'singularity' where the density of the Universe would be infinite. Instead, the Big Bang stretches out in the past over an essentially infinite period of time. And the current cosmos could be static, or even beginning to contract.


Whoa. That is a radically different picture of the Universe than what we're used to.

Unfortunately, there’s no way for us to test this. Well, at least not yet.

But Wetterich 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.

Read the entire study — which has not yet been peer reviewed — at arXiv: “A Universe without expansion.” But as Cartwright notes in his article, other physicists are not hating the idea.