Portsmouth: New Test of Dark Energy & Expansion

[bystander]

New Test of Dark Energy and Expansion from Cosmic Structures
University of Portsmouth, UK | 2020 Jun 03

A section of the three-dimensional map of galaxies Sloan Digital Sky Survey used in this analysis. The rectangle on the far left shows a patch of the sky containing nearly 120,000 galaxies (a small fraction of the total survey). The centre and right images show the 3D map created from these data: brighter regions correspond to the regions of the Universe with more galaxies, and darker regions to voids. Image credit: Jeremy Tinker and the SDSS-III collaboration

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A new paper has shown how large structures in the distribution of galaxies in the Universe provide the most precise tests of dark energy and cosmic expansion yet.

The study uses a new method based on a combination of cosmic voids – large expanding bubbles of space containing very few galaxies – and the faint imprint of sound waves in the very early Universe, known as baryon acoustic oscillations (BAO), that can be seen in the distribution of galaxies. This provides a precise ruler to measure the direct effects of dark energy driving the accelerated expansion of the Universe.

This new method gives much more precise results than the technique based on the observation of exploding massive stars, or supernovae, which has long been the standard method for measuring the direct effects of dark energy. ...

This new method gives much more precise results than the technique based on the observation of exploding massive stars, or supernovae, which has long been the standard method for measuring the direct effects of dark energy. ...

Testing Low-Redshift Cosmic Acceleration with Large-Scale Structure ~ Seshadri Nadathur et al

• Physical Review Letters 124(22):1301 (05 Jun 2020) DOI: 10.1103/PhysRevLett.124.221301
• arXiv.org > astro-ph > arXiv:2001.11044 > 29 Jan 2020 (v1), 21 May 2020 (v2)

[Ann]

Chieftain Vitalstatistix of a tiny Gaulish that bravely fight the Romans during the time of the Roman Empire. Illustration: Albert Uderzo.

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I was very glad to see yet another study that supports the claim that the Universe is accelerating and will most probably keep expanding instead of collapsing in on itself.

The idea that the Universe might crunch itself into a tiny point was the most horrifying idea I had ever come across when I first learned about this hypothesis back when I was in my teens.

As I kid I enjoyed reading about Asterix and Obelix. They lived in a small Gaulish village that refused to give in to the Roman Empire. Their chieftain was called Vitalstatistix, and the only thing he feared was the prospect of the sky falling on his head.

It took me several years to make the connection, but I finally realized that Vitalstatistix was really afraid of the Big Crunch, when, if it happens, the Universe will fall in on itself and squeeze everything out of existence.

But hey, Vitalstatistix, it's not just the sky that will fall on your head. The floor will also rise up from the, well, floor, and the walls, or the open horizon, will close in on you.

The thought makes me shudder. I know: There will be no walls or floors left at the time of a possible Big Crunch. Even so, I abhor the idea.

Ann

P.S. I apologize that the picture I have posted is too big. It doesn't look so byte-rich to me. I hope it will by okayed by the moderators.