Cosmologist claims Universe may not be expanding (2013)
I know Christoff Wetterich! From the time of my Ph.D. when we were working the Renormalization Group. I met him a few times, we were working on similar things but in different groups, we were "competitors" if you wish. Funny to see him cited in HackerNews. He is certainly a respectable physicists, but that can be said for many others. I have not read the cited article, it is in my field, so I could understand it if my memory worked well, but after 20 years from my Ph.D. I am too rusted now.
The central concept behind Christof Wetterich's proposal is scale invariance: Imagine you try to measure the size of the universe with a yard stick. If you measure that the universe is expanding, you can't be sure that it really is the universe expanding, or maybe just your yard stick shrinking.
This is true in so-called scale invariant theories. These theories do not contain any intrinsic length scale. The moment your theory contains a fundamental length l you break scale invariance. In this case you are able to compare your yard stick to the length l to find out if your yard stick was shrinking or the universe really is expanding.
Our present model of the world still contains a few fundamental length scales (such as the Planck length, or a length scale associated to the nuclear force), but people such as Christof Wetterich are building models that try to get rid of (some of) these fundamental length scales. A major approach in this direction is asymptotically safe quantum gravity, that also led Christof Wetterich and Mikhail Shaposhnikov to the most precise prediction of the Higgs mass prior to the Higgs' discovery in 2009, see https://arxiv.org/abs/0912.0208.
This is (2013). Christof Wetterich continued research, his current theory is called emergent scale symmetry: https://arxiv.org/abs/1705.00552. It got peer-reviewed and published at Physical Reviews D, the leading journal on cosmology.
Interesting take on things. There's value in thinking about equivalent models that allow potentially entrenched assumptions to be set aside. Worth mentioning that the kilogram has since been defined more robustly than the way mentioned in the article. https://www.sciencealert.com/it-s-official-the-definition-of...
> The idea may be plausible, but it comes with a big problem: it can't be tested.
Doesn't that imply that the accepted model can't be tested? I mean, in the sense of distinguishing it from this one.
Within galaxies, however, gravity dominates dark energy expansion, right? If so, with enough measurement accuracy shouldn't we be able to look for standard candles within our galaxy that either show or don't show said mass differences while compensating for any shift due to relative motion? I'd think that given enough accuracy we'd have something that's testable eventually.
Reminds me of my funny notes in a childhood diary. I had a personal pet theory that Dinosaurs were so huge because they were not as heavy as we assumed them to be. Imagining what it felt like to be a dino was a steady staple for boring afternoons.
Wouldn't the gravitational pull increase? For example you would see less gravitational lensing in older galaxy clusters.
The universe isn't expanding. It's everything in it that's shrinking!
This seems testable enough... The speed of light isn't in question here, so the frequency is the yardstick. Can't we just record the frequencies given off by the elements every hundred years or so and see that they are the same?
What are the theories on what we think the edge of the universe looks like? What does it even mean? Will we just hit an invisible wall like in a video game? Or do we think it’s curved around the edge? Or what?
If it’s expanding, what is it expanding into?
We observe from a far distant star the red shifted spectrum. This is explained by the expansion of the galaxy and the expanding room between us and this star. So the photons coming from there have a red-shifted and hence lesser engery. What has happend to the energy of the photon? Where's it gone to?
I can't see why the article would say the effect is not measurable. We are trying to contrast two explanations: In one, galaxies are receding and the expansion of space in the intervening distance red shifts the spectra. In the other masses are changing (globally?) as some rate, changing the spectra.
The best modern atomic clocks depend on atomic spectra, a shift in which would be evidence for or against this model.
Given the precision of modern atomic clocks (<10^-17)[1] and the fact that the galactic spectral shifts are significant at large distances this seems plausible. I don't have precise #'s to do the calculations at hand so maybe I've made an error.
There is also the opposite scenario, the Big Rip: https://www.youtube.com/watch?v=gEyXTQ9do-c
Kind of related to something that I've been chewing on:
I've read things (outside of the OP) that say the universe is expanding and also speeding up it's expansion, as neighbors exert less of a pull on each other the further spread out things get. However, that gravitational pull is still there -- will it at any point slow down the expansion and retract back inwards?
Wouldn't this theory rule out dark energy since I believe dark energy is used to explain an accelerating, expanding universe?
> Conversely, if the particles were to become lighter, the frequencies would become redshifted.
> If all masses were once lower, and had been constantly increasing, the colours of old galaxies would look redshifted
Can anyone explain this apparent contradiction?
>Instead, the Big Bang stretches out in the past over an essentially infinite period of time.
So the timeline according to this theory is [Big Bang] - >[Inflation] - >[Increase in mass] & we're seeing the redshift from that?
Head hurts, I love it.
Alvie would be pleased to know that Brooklyn is not expanding.
Does this mean that G is not contant? And would it throw away all our calculations of distances of galaxies in the known Univers?
We know there is an equivalence between mass an energy.
Does this view imply that new energy is appearing in the universe?
As my imagination, the Big Bang is the collision of two universes in the past.
What does the Universe expand into?
could this help explain the mass of the several copies of the kilogram drifting apart?
We've been screaming this for years, but only a controlled opposition will not be censored. 99% of matter is plasma, so to say electromagnetic laws do not rule the universe... And you're more brainwashed than anyone.
the universe is shrinking.
dinosaurs -> humans
microbeA -> microbeB