May 30, 2021 02:40 AM
https://www.forbes.com/sites/startswitha...ultiverse/
EXCERPT: . . . What inflation postulated was that the reason the total energy density and the expansion rate balanced so perfectly is that the Big Bang wasn’t the very beginning of everything, but rather was preceded by what’s known as an inflationary phase: where there’s no matter, antimatter, or radiation, but rather where the expansion of the Universe is determined by a form of energy inherent to space itself.
[...] During inflation, the expansion is relentless: space everywhere expands at the same rapid, constant rate. You can imagine that this space is like a sea of water, and that the sea is expanding: more and more water appears as time goes on.
Then you can imagine that inflation ends in some regions, and these are like little tiny bubbles that form and grow, similar to how a pot of boiling water starts with tiny bubbles that nucleate and grow. But unlike in a pot of boiling water, the “expanding” nature of the sea drives these individual bubbles apart; they grow, but the expanding sea between them grows relatively faster, ensuring that any two individual bubbles will never collide.
That’s the standard picture of cosmic inflation, along with how and why it creates a Multiverse. In fact, once inflation begins, there will always be regions between any two places where inflation ends that keep on inflating; in this sense, inflation is eternal. However, we can only observe the Universe where we exist within it, and that’s where a hot Big Bang occurred some 13.8 billion years ago. And to no one’s surprise, there’s no evidence of a bubble collision having occurred in the early Universe, as the imprint such an event would have left is nowhere to be seen.
The take home message is this: in order to get enough inflation to explain the Universe we observe, the field responsible for it needs to have certain properties. If it has those properties, we can not only explain everything that the Big Bang without inflation could, we also explained things that the Big Bang alone could not, plus make new predictions that have subsequently been tested and confirmed.
However, there’s another consequence that cannot realistically be avoided that comes along for the ride: a Multiverse, where many independent universes are created within it that never interact, overlap, or collide with one another. We have no evidence that the Multiverse exists, of course; the only variants that would have observable consequences involve “bruises” on our Universe, which are inconsistent with what we see. Everything still lines up with the simplest models of inflation, nearly 40 years after their initial proposal. Perhaps it’s time to stop paying attention to the doubting Thomases out there, and to instead embrace the Universe exactly as it shows itself to be... (MORE - missing details)
EXCERPT: . . . What inflation postulated was that the reason the total energy density and the expansion rate balanced so perfectly is that the Big Bang wasn’t the very beginning of everything, but rather was preceded by what’s known as an inflationary phase: where there’s no matter, antimatter, or radiation, but rather where the expansion of the Universe is determined by a form of energy inherent to space itself.
[...] During inflation, the expansion is relentless: space everywhere expands at the same rapid, constant rate. You can imagine that this space is like a sea of water, and that the sea is expanding: more and more water appears as time goes on.
Then you can imagine that inflation ends in some regions, and these are like little tiny bubbles that form and grow, similar to how a pot of boiling water starts with tiny bubbles that nucleate and grow. But unlike in a pot of boiling water, the “expanding” nature of the sea drives these individual bubbles apart; they grow, but the expanding sea between them grows relatively faster, ensuring that any two individual bubbles will never collide.
That’s the standard picture of cosmic inflation, along with how and why it creates a Multiverse. In fact, once inflation begins, there will always be regions between any two places where inflation ends that keep on inflating; in this sense, inflation is eternal. However, we can only observe the Universe where we exist within it, and that’s where a hot Big Bang occurred some 13.8 billion years ago. And to no one’s surprise, there’s no evidence of a bubble collision having occurred in the early Universe, as the imprint such an event would have left is nowhere to be seen.
The take home message is this: in order to get enough inflation to explain the Universe we observe, the field responsible for it needs to have certain properties. If it has those properties, we can not only explain everything that the Big Bang without inflation could, we also explained things that the Big Bang alone could not, plus make new predictions that have subsequently been tested and confirmed.
However, there’s another consequence that cannot realistically be avoided that comes along for the ride: a Multiverse, where many independent universes are created within it that never interact, overlap, or collide with one another. We have no evidence that the Multiverse exists, of course; the only variants that would have observable consequences involve “bruises” on our Universe, which are inconsistent with what we see. Everything still lines up with the simplest models of inflation, nearly 40 years after their initial proposal. Perhaps it’s time to stop paying attention to the doubting Thomases out there, and to instead embrace the Universe exactly as it shows itself to be... (MORE - missing details)
