"While leaving physical measurements unaffected, this can offer a reinterpretation and even solutions of these problems. In this spirit, metric transformations are performed here that cast our Universe into different geometries."
No own opinion... yet...
edit: and most certainly won't as I read on - this one is for Steve ;-)
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- Abstract
- 1. Introduction
- 2. Gravity in different casks
- 3. Casting cosmology into Minkowski space
- ....
No own opinion... yet...
edit: and most certainly won't as I read on - this one is for Steve ;-)
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I've only looked at the abstract.
"Metric transformations are performed here that cast our Universe into different geometries."
These transformations are said to involve a variation of mass, length and time scales across spacetime.
Dark matter, dark energy, inflation and baryogenesis are mentioned as "promising candidates of geometric origin".
If this "reframed cosmological picture" can replace the expansion of space and spatial curvature etc., then who am I to disagree? 🤓
Not being a theoretical physicist with too much time on my hands, I will simply skip the maths and gather together the main conclusions.
- Cosmic expansion is reinterpreted as an evolution of particle masses with time.
- The Universe is spatially curved due to a variation of time, length and mass scales across spacetime.
- Dark energy and dark matter are interpreted as particle masses that respectively diverge and converge as the Universe ages.
- The current tensions between measurements of the Hubble constant are solved.
- Photons emitted from galaxy clusters may be significantly more redshifted than expected, which may explain recent observations that galaxy clusters are older and more distant than previously thought.
Why would particle masses evolve over time? Why would dark energy and dark matter simply be because particle masses ‘diverge and converge’ over time? What does that even mean? And if particle masses ‘diverge and converge’ over time, what does that say about the Higgs bosun and its attendant Higgs field that are supposed to impart mass to particles?
And all of this is supposed to be taking place on the ‘canvas of time’.
We lost our way IMV.
And all of this is supposed to be taking place on the ‘canvas of time’.
We lost our way IMV.
Don't mess with the Minkowski metric - that's what I'd tell them! 
It's the metric of the four-dimensional flat spacetime that obeys Special Relativity.
Works for me!
It's the metric of the four-dimensional flat spacetime that obeys Special Relativity.
Works for me!
The problem with post #2787 (not your words, but those extracted from the paper) is that it does not answer fundamental questions without immediately raising others. Einstein's SR and GR solved some long-standing issues within classical physics, as did Newton's Principia 350 years before that, or Maxwell's equations in 1865. We only became aware of some shortcomings when we discovered the universe was expanding (Edwin Hubble about 1927) and now, since 1996 with the discovery by Adam Reiss et al, the expansion was accelerating. This new paper immediately raises questions as to why numerous phenomena, some of which are not apparent at first sight, behave the way they do. Unzicker (and to some extent Hossenfelder and Seagal) talk about this and why modern physics is in crisis. And let's not start on string theory. Witten, Greene, and Rovelli are still banging on about string theory and IIUC the number of dimensions has now jumped to 26 and we have absolutely no way of doing any experiment that could verify any of this stuff. I think what's happened here is these guys have come up with a horrendously complex idea of how the universe hangs together, and then written an equation that describes their model. If you've ever watched one of Brian Greene's string theory YT video's, it is clear the guy chose the wrong profession. I really could have used him in semiconductor sales when I ran a product line 😀
I could be complex.... but it could also be "simple"... hopefully we live long enough to see someone sort out the "crisis" - which I think is a bit of a created drama. Science is doing its thing...properly... w'll get there 🙂
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As I interpret it, the idea behind the theory linked to by TNT is to play around with different ways of combining the Einstein field equations with the geometries of the Universe.
The FLRW (Friedmann, Lemaitre, Robertson, Walker) metric describes the large scale features of the Universe and predicts three geometries.
The simplest geometry is Minkowski spacetime which is flat, and provides a level playing field (pun intended) for the combining game.
(Note that the descriptions sphere, flat, and saddle-like refer to the rules of geometry and do not mean that all of the stuff in the universe is arranged as if it lies on the surface of a sphere, a plane, or a saddle.)
The FLRW metric includes a term a(t) called the 'scale factor' which is responsible for scaling the distance between objects that have different spatial coordinates.
This scale factor increases with time and is responsible for the expansion of spacetime.
Alexander Friedmann came up with an equation that combined the FLRW metric with the Einstein Field equations and discovered a way to determine a(t).
What the authors of the IOP article appear to have essentially done is to re-derive the Friedmann equation and to hypothesise alternative ways to explain the expansion of spacetime.
Unfortunately, they can't explain their conclusions in a way that makes any sense to a mere mortal like myself! 🤓
The FLRW (Friedmann, Lemaitre, Robertson, Walker) metric describes the large scale features of the Universe and predicts three geometries.
The simplest geometry is Minkowski spacetime which is flat, and provides a level playing field (pun intended) for the combining game.
(Note that the descriptions sphere, flat, and saddle-like refer to the rules of geometry and do not mean that all of the stuff in the universe is arranged as if it lies on the surface of a sphere, a plane, or a saddle.)
The FLRW metric includes a term a(t) called the 'scale factor' which is responsible for scaling the distance between objects that have different spatial coordinates.
This scale factor increases with time and is responsible for the expansion of spacetime.
Alexander Friedmann came up with an equation that combined the FLRW metric with the Einstein Field equations and discovered a way to determine a(t).
What the authors of the IOP article appear to have essentially done is to re-derive the Friedmann equation and to hypothesise alternative ways to explain the expansion of spacetime.
Unfortunately, they can't explain their conclusions in a way that makes any sense to a mere mortal like myself! 🤓
Clip from HG Wells‘ The Time Machine, test of his contraption, note that as time changes all the physical dimensions remain constant.
Wells' novella is a work of fiction.
I do love the special effects in the 1960 film.
But how could either be salient to our current discussion?
I do love the special effects in the 1960 film.
But how could either be salient to our current discussion?
I have the DVD in my large collection of vintage Sci-Fi movies.
Tread carefully, Geoff, or you may be grabbed by the Morlocks! 😱
Like the corridor in the pyramid, the purpose of your post may not be entirely clear to everyone.
Muon imaging is interesting and involves cosmic radiation: https://en.wikipedia.org/wiki/Muon_tomography
I visited as a child, but got lost and couldn't find my mummy! 😀