I suspect that Sabine will be battered and bruised (worn out) after yet again saying to theorists "Get out of your bubble"!
What interests me is that theorists keep talking about the cosmos being both isotropic and homogeneous and then use that to put forth that the universe therefore can’t have large voids or thermal discontinuities as in the article you linked to above. But, if it was any of these things, then galaxies and matter would surely be evenly spread across the universe with no clumping and no large voids? But, what we see are distinct thermal differences (0.1K IIRC) which is a big deal if you are considering things on a cosmological scale. We see matter clumping as in galaxy clusters with vast filaments connecting them. In the first few hundred million years of the universe’s existence, there would have been millions of hypergiant stars going supernova and sending shock waves through the cosmos, black hole and neutron star mergers generating gravity waves and all of this activity would have caused clumping, voids and so on. I don’t know, but suspect some of the issues around the Hubble tension are precisely because the universe is quite lumpy, and if that is the case, time would be passing at different rates and that in turn would affect the Hubble constant depending upon which direction one was looking at.
Very perplexing.
Very perplexing.
Last edited:
Could we a-void the Hubble tension with a local void?
The CMB gives a snapshot of the structure of the infant universe, suggesting that matter today should be rather uniformly spread out. However, directly counting the number of galaxies in different regions suggests we are in a local void - an area which is well below average density.
An under-density could resolve the apparent tension between predictions of the Hubble constant based on the CMB and measurements based on nearby galaxies and supernovae - the latter presenting a figure that is 10% larger.
A new paper discusses the possibility that outflows of matter from our local void could inflate local measurements of the Hubble constant. Outflows would arise because denser regions surrounding our void would exert a bigger gravitational pull than the lower density matter inside our void.
https://scitechdaily.com/lost-in-space-is-a-giant-void-driving-the-universe-apart/
I scanned through the doc quickly and on the face of it, is it much different to what I was suggesting earlier? If you look in different directions, why would you expect to get the same HC? It simply reinforces my small brain view that the cosmos may not be as isotropic or homogeneous as we believe and that’s because small perturbations in the early universe coupled to later gravitational effects would amplify the differences in galaxy density so now they are mostly found in clusters.
The interesting bit here is a whole lot of accepted cosmology says the universe is isotropic and homogeneous but observations don’t seem to gel with that.
BTW, the comments below the piece are priceless like this gem (sounds like a long since banned troll who used to frequent this site): -
Fixed gravity for you. | December 2, 2023 at 2:33 am | Reply
An explanation using multi-scalar filaments of gravitational spin flow, recently shown at one scale in the side-scatter of bright columns of aligned spinning protons lounging around near the galactic center, unfortunately does not resort to the extradimensional spacetime continuum heavenly firmament type of void theory enjoyed by LCDM+ science funding royalty.
Basically, the idea was to equate said filaments with paths of enhanced gravity flows, thus with enhanced red-shifting, cosmological coherence/entanglements, and filamentary dark matter effects. On top of that, the teetering notion that, in any average bound set of filaments, the distribution of filament lengths will normally tend to skew toward shorter filaments, was precariously piled, with absolutely no extradimensional support whatsoever. As it could not be visualized with a magic marker and a heavenly inspired imperial balloon, it was most properly deemed hopeless, totally unprofessional, and without merit.
The interesting bit here is a whole lot of accepted cosmology says the universe is isotropic and homogeneous but observations don’t seem to gel with that.
BTW, the comments below the piece are priceless like this gem (sounds like a long since banned troll who used to frequent this site): -
Fixed gravity for you. | December 2, 2023 at 2:33 am | Reply
An explanation using multi-scalar filaments of gravitational spin flow, recently shown at one scale in the side-scatter of bright columns of aligned spinning protons lounging around near the galactic center, unfortunately does not resort to the extradimensional spacetime continuum heavenly firmament type of void theory enjoyed by LCDM+ science funding royalty.
Basically, the idea was to equate said filaments with paths of enhanced gravity flows, thus with enhanced red-shifting, cosmological coherence/entanglements, and filamentary dark matter effects. On top of that, the teetering notion that, in any average bound set of filaments, the distribution of filament lengths will normally tend to skew toward shorter filaments, was precariously piled, with absolutely no extradimensional support whatsoever. As it could not be visualized with a magic marker and a heavenly inspired imperial balloon, it was most properly deemed hopeless, totally unprofessional, and without merit.
My intention was to reinforce your idea (apart from the "time would be passing at different rates" bit!).
As Stephen Hawking put it, "The assumption that the universe looks the same in every direction is clearly not exactly true in reality".
However, he went on to say that the universe does appear to be roughly the same in every direction provided we view it on a large scale compared to the distance between galaxies.
He likens this to a forest where if you look in one direction, you may see the nearest tree at a distance of 1 metre. In another direction the nearest tree may be 3 metres away. In a third direction, you may see a clump of trees 2 metres away. However, if you were to take into account all the trees in a one-mile radius these kinds of differences would average out and you would find that the forest appears identical in whichever direction you look.
The new paper to which I referred in post #3,844 talked of non-uniformity in our local neighbourhood and does not deny that the universe is isotropic on the large scale.
(Hawking's views are adapted from A Briefer History of Time.)
But, if you are using the HC and looking back over vast timespans, we still get a range of 67 to 73km/mpc. Surely that must tell us it is not the same in every direction? Unless of course, the measurements are wrong. One way to settle this is to scan the exact same areas of the sky with different instruments and see if they tally.
We simply need more data - more Cepheid variables - more Type Ia supernovae - more Red Giant stars.
Something that the forthcoming Nancy Grace Roman Space Telescope, with its 100 times greater view of the sky than Hubble, will provide.
By measuring the distances of thousands of supernovae, astronomers will be able to map cosmic expansion in detail.
https://www.jpl.nasa.gov/missions/the-nancy-grace-roman-space-telescope
Something that the forthcoming Nancy Grace Roman Space Telescope, with its 100 times greater view of the sky than Hubble, will provide.
By measuring the distances of thousands of supernovae, astronomers will be able to map cosmic expansion in detail.
https://www.jpl.nasa.gov/missions/the-nancy-grace-roman-space-telescope
In the set of websites known to not lock up my operating system or browser, this wikipedia article covers the same data adequately, I hope. https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telescope
Uses a salvaged image device from the US National Reconnaissance Office, to the satisfaction of some of us thrifty taxpayers.
Now if only the surplus Titan missiles could be converted to subway propulsion.
Uses a salvaged image device from the US National Reconnaissance Office, to the satisfaction of some of us thrifty taxpayers.
Now if only the surplus Titan missiles could be converted to subway propulsion.
Last edited:
Magnetic fields around our galaxy's black hole.
https://eventhorizontelescope.org/blog/astronomers-unveil-strong-magnetic-fields-spiraling-edge-milky-way’s-central-black-hole
https://eventhorizontelescope.org/blog/astronomers-unveil-strong-magnetic-fields-spiraling-edge-milky-way’s-central-black-hole
Astronomers have predicted that spinning, winding and snapping magnetic fields lines of a supermassive black hole interact with the material in the accretion disc to generate the energy to power the spinning jet ejected by active galaxies such as M87 (imaged below).
A previous polarised light image backed up that prediction in the case of M87.
The new polarised image of Sagittarius A* shown in rayma's post is similar to that of the supermassive black hole at the centre of M87, suggesting that the Milky Way galaxy may have a hidden jet.
I think the jets are only activated (visible) when matter falls into the BH - the central black hole in the Milky Way is dormant at present but the mag fields are there but not visible. The MEERKAT radio telescope got image of giant filaments around Sag A* that might be linked to the mag field.
https://astronomynow.com/2022/01/26/meerkat-paints-a-mesmerising-portrait-of-the-milky-way/
https://astronomynow.com/2022/01/26/meerkat-paints-a-mesmerising-portrait-of-the-milky-way/
For those who don't open links, I am posting the image and its description.
"Sagittarius A*, the 4-million-solar-mass black hole at the core of the Milky Way shows up as a blaze of surrounding radio emissions, along with huge magnetised radio filaments in cirrus-like arcs."
Quoting from rayma's link, "This similarity [between the magnetic field structure of Sgr A* and the black hole at the centre of M87] also hints toward a hidden jet in Sgr A*.
Unlike M87, the Milky Way is not considered to be an active galaxy, but could there actually be a "hidden jet", and why is it hidden?
The more comprehensive article below says astronomers have yet to detect that jet, but if they do, "it might imply that almost every galaxy may have a hidden jet lurking at its centre, but that we actually usually miss them because they're simply too weak".
https://www.msn.com/en-us/news/tech...lack-hole-could-have-a-hidden-jet/ar-BB1kD0RI
Scroll down and you will come to a section entitled "A Hidden Jet?" in which we are told that while previous studies have found evidence for a jet from Sgr A*, it has never been directly imaged. The Event Horizon Telescope team thinks it can directly detect the jet in the next two years.
Our knowledge of the universe is ever increasing!
The Milky Way has two enormous lobes that extend above and below the galactic plane out to about half a million LY each side. These could be the result of material delivered by the jets when Sag A* was much more active over 100’s of millions of years. I read somewhere that as recently as 5 million yrs ago, Sag A* had active jets.
In other galaxies, the visible jets can extend out for thousands of LYs and travelling at 500k mph. Truly awesome power.
Our knowledge is indeed growing by the day Galu!
In other galaxies, the visible jets can extend out for thousands of LYs and travelling at 500k mph. Truly awesome power.
Our knowledge is indeed growing by the day Galu!
Yes, there is evidence to suggest that the Milky Way galaxy may have been active just a few million years ago.
This evidence is in the form of two giant bubbles that extend 25,000 light-years above and below the galactic centre and are emitting gamma rays.