Mass is expanding says this physicist

Cosmologist claims Universe may not be expanding

In a paper posted on the arXiv preprint server¹, Christof Wetterich, a theoretical physicist at the University of Heidelberg in Germany, has devised a different cosmology in which the Universe is not expanding but the mass of everything has been increasing. Such an interpretation could help physicists to understand problematic issues such as the so-called singularity present at the Big Bang, he says.

Hey, he noticed something:

But, as Wetterich points out, the characteristic light emitted by atoms is also governed by the masses of the atoms' elementary particles, and in particular of their electrons. 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.

This is not true:

The idea may be plausible, but it comes with a big problem: it can't be tested. Mass is what’s known as a dimensional quantity, and can be measured only relative to something else. For instance, every mass on Earth is ultimately determined relative to a kilogram standard that sits in a vault on the outskirts of Paris, at the International Bureau of Weights and Measures. If the mass of everything — including the official kilogramme — has been growing proportionally over time, there could be no way to find out.

We can count mass up, just like nature does. Just change the units to "thing counted up"

Here is a careful physicist:

Others say that Wetterich’s interpretation could help to keep cosmologists from becoming entrenched in one way of thinking. “The field of cosmology these days is converging on a standard model, centred around inflation and the Big Bang,” says physicist Arjun Berera at the University of Edinburgh, UK. “This is why it’s as important as ever, before we get too comfortable, to see if there are alternative explanations consistent with all known observation