Mar 17, 2023 07:11 PM
(This post was last modified: Mar 17, 2023 07:11 PM by C C.)
The hot Big Bang is often touted as the beginning of the Universe. But there's one piece of evidence we can't ignore that shows otherwise.
https://bigthink.com/starts-with-a-bang/...-big-bang/
KEY POINTS: For many decades, people conflated the hot Big Bang, describing the early Universe, with a singularity: that this "Big Bang" was the birth of space and time. However, in the early 1980s, a new theory called cosmic inflation came along, suggesting that before the hot Big Bang, the Universe behaved very differently, pushing any hypothetical singularity unobservably far back. Earlier this century, some very strong evidence arrived showing that there was a Universe before the Big Bang, demonstrating that the Big Bang wasn't truly the start of it all.
EXCERPT: . . . As you can clearly see, there can be no doubt that there truly are super-horizon fluctuations within the Universe, as the significance of this signal is overwhelming. The fact that we see super-horizon fluctuations, and that we see them not merely from reionization but as they are predicted to exist from inflation, is a slam dunk: the non-inflationary, singular Big Bang model does not match up with the Universe we observe. Instead, we learn that we can only extrapolate the Universe back to a certain cutoff point in the context of the hot Big Bang, and that prior to that, an inflationary state must have preceded the hot Big Bang.
We’d love to say more about the Universe than that, but unfortunately, those are the observable limits: fluctuations and imprints on larger scales leave no effect on the Universe that we can see. There are other tests of inflation that we can look for as well: a nearly scale-invariant spectrum of purely adiabatic fluctuations, a cutoff in the maximum temperature of the hot Big Bang, a slight departure from perfect flatness to the cosmological curvature and a primordial gravitational wave spectrum among them. However, the super-horizon fluctuation test is an easy one to perform and one that’s completely robust.
All on its own, it’s enough to tell us that the Universe didn’t start with the hot Big Bang, but rather that an inflationary state preceded it and set it up. Although it’s generally not talked about in such terms, this discovery, all by itself, is easily a Nobel-worthy achievement... (MORE - missing details)
https://bigthink.com/starts-with-a-bang/...-big-bang/
KEY POINTS: For many decades, people conflated the hot Big Bang, describing the early Universe, with a singularity: that this "Big Bang" was the birth of space and time. However, in the early 1980s, a new theory called cosmic inflation came along, suggesting that before the hot Big Bang, the Universe behaved very differently, pushing any hypothetical singularity unobservably far back. Earlier this century, some very strong evidence arrived showing that there was a Universe before the Big Bang, demonstrating that the Big Bang wasn't truly the start of it all.
EXCERPT: . . . As you can clearly see, there can be no doubt that there truly are super-horizon fluctuations within the Universe, as the significance of this signal is overwhelming. The fact that we see super-horizon fluctuations, and that we see them not merely from reionization but as they are predicted to exist from inflation, is a slam dunk: the non-inflationary, singular Big Bang model does not match up with the Universe we observe. Instead, we learn that we can only extrapolate the Universe back to a certain cutoff point in the context of the hot Big Bang, and that prior to that, an inflationary state must have preceded the hot Big Bang.
We’d love to say more about the Universe than that, but unfortunately, those are the observable limits: fluctuations and imprints on larger scales leave no effect on the Universe that we can see. There are other tests of inflation that we can look for as well: a nearly scale-invariant spectrum of purely adiabatic fluctuations, a cutoff in the maximum temperature of the hot Big Bang, a slight departure from perfect flatness to the cosmological curvature and a primordial gravitational wave spectrum among them. However, the super-horizon fluctuation test is an easy one to perform and one that’s completely robust.
All on its own, it’s enough to tell us that the Universe didn’t start with the hot Big Bang, but rather that an inflationary state preceded it and set it up. Although it’s generally not talked about in such terms, this discovery, all by itself, is easily a Nobel-worthy achievement... (MORE - missing details)
