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Are we living in a vast bubble? Rob Sheldon explains

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It may impact the 2011 Nobel Prize:

The few thousand galaxies closest to us move in a vast ‘bubble’ that is 250 million light years in diameter, where the average density of matter is half as large as for the rest of the universe. This is the hypothesis put forward by a theoretical physicist to solve a conundrum that has been splitting the scientific community for a decade: at what speed is the universe expanding?

Université de Genève, “Expanding universe: We may be in a vast bubble” at ScienceDaily

Our physics color commentator, Rob Sheldon, comments,

This professor at Geneva proposes to resolve the “Hubble tension” between the PLANCK consortium value of 67 km/s/Mpc and the astronomy consensus 72 km/s/Mpc by positing a giant 250Mpc bubble around the Milky Way galaxy. It’s not a new idea (see #5 in archived 2011 link below), but it sounds like he’s put some work into making the bubble more defined.

But what he doesn’t say, is that this invalidates the 2011 Nobel prize which assumed at most a 100Mpc radius disturbance in the supernovae Ia spectra. So now a French cosmologist is supporting the Oxford cosmologist Subir Sarkar in refuting the US-dominated 2011 Nobel prize consensus.

Looks like a dethronement, or rather, a defenestration of the US dominance. Who knows, maybe they’ll take the prize back and I can unblock Stockholm on my phone.

Stay tuned. That 2011 Prize for gravitational waves has often been a topic of conversation here.

Rob Sheldon, is the author of The Long Ascent I and The Long Ascent II.

Robert Sheldon Thank you for the explanation. I think I now understand, more or less. Fasteddious
Fasteddious, Slightly more complicated than that. The acceleration is related to the size of the universe, so when the universe was young, it didn't accelerate appreciably, only after the universe got to be our present size did it begin to accelerate. The Hubble constant is computed as if the universe never accelerates. Furthermore, it is an integration over the whole time of the universe, so it is heavily weighted toward recent numbers. So the two methods should "in principle" be much closer. Adding to the complication, Subir Sarkar says that our region of the universe some 250 Mpc wide is moving with respect to the rest of the universe. This motion befuddles the supernovae fit, since most of the SN/Ia in the data set is behind us, where it looks abnormally red-shifted. Once this motion is removed, the rest of the universe doesn't appear to be abnormally red-shifted, and thus there is no acceleration going on, and hence the 72 km/s/Mpc is the right number. Robert Sheldon
There is a Scientific American article this month about this discrepancy. The method for measuring the expansion of the Universe using those supernovae looks at "nearby" galaxies and gets the 72 value for the Hubble constant, Ho. The method that analyses the background radiation, and hence looks at the farthest away - and hence oldest - parts of the Universe, gets the lower number, 67. My simple engineering mind read this and thought, "well if the expansion is accelerating, then the more recent value of Ho should be more than the earlier value, so what is the problem?" I am sure that explanation is far too simplistic for serious cosmologists, but perhaps one of the physics and cosmology readers here can correct my thinking by explaining how an accelerating expansion rate does not increase over billions of years? Fasteddious

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