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Why We Think There's a Multiverse, Not Just Our Universe
An anonymous reader writes "It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework. It's also accepted that the Universe probably started off with an early period of cosmic inflation prior to that. Well, if you accept those things — as in, the standard picture of the Universe — then a multiverse is an inevitable consequence of the physics of the early Universe, and this article explains why that's the case."
But the turtles appear out of nowhere and are very far apart.
Why do cosmological theories of any merit always sound like they were written by Douglas Adams?
Please do not read this sig. Thank you.
Note that this isn't talking about the quantum mechanical multiverse where whenever a decoherence occurs you get branching of different copies. This is talking about a more concrete notion of multiverse where the early inflation spreads out so much that there are lots of little regions of observable space time which cannot observe each other.
or something less stupid, instead?
It doesn't make any sense to say that it's one big thing, but not one big thing at the same time.
Kind of like saying it's not one big cake sliced into wedges, it's lots of little cakes that have nothing to do with each other.
AND YET THEY OCCUPY THE SAME PLATTER.
I think that this is a great article, but...
It is obvious that there are parts of the universe that are not (and never have been) causally connected with our universe.Those are just the parts of our universe we can't see, which are inevitable in an infinite universe with a finite duration and a finite speed of light. You don't need either quantum mechanics or inflation for that, and it has never been called the "multiverse."
The multiverse in my experience means exclusively the idea that there are other parts of the universe with different physical laws. That idea is connected to the anthropic principle, and (IMHO) evading tough issues about the nature of physical laws. (Find the cosmological constant to be inconveniently small? That's OK! In a multiverse there are a gazillion universe with large cosmological constants and no life like ours, ours with a small one and our kind of life, and nothing left to explain!) "We" might think that there is that kind of multiverse, but "we" in this case decidedly does not include "me." (People like me tend to call such ideas "Just so stories," which in physics is an insult.)
I know it's karma suicide to post on something like this saying "I don't get it", but, well, I don't get it.
I've been reading about inflation, multiverses, and whatnot for a very long time at this point, and I like to think that I can give a reasonable explanation comprehensible to nontechnical people. I've come across some articles that were a lot of work to get through, and I've given up on some because I don't have the necessary math.
But this article was terrible. Its grammar is good and not overly complex; it doesn't use a lot of obscure words. It's written like a nice popularization piece, with important parts called out in bold and lots of illustrations. But the illustrations are baffling -- what's that "getting closer to a sphere" four-panel diagram credited to Ned Wright, and where does the text refer to it? What the heck is going on with those diagrams from Narlikar and Padmanabhan? What's with the black space-balls rolling around on the mini-golf course at the end?
I'd wonder if this is a Sokol-type troll, but I don't see anything obviously wrong in it -- there's just a bunch of stuff there that looks like explanations, but apparently isn't. Or maybe I'm just having a bad night.
I mean, I can handle the concept... so long as there's just ONE multiverse.
I thought there were already concise terms for it. The universe IS the multiverse / partitioned universe. The part that we are in is called observable universe.
Better known as 318230.
The President is very much a figurehead - he wields no real power whatsoever. He is apparently chosen by the party caucus, but the qualities he is required to display are not those of leadership but those of finely judged outrage. For this reason the President is always a controversial choice, always an infuriating but fascinating character. His job is not to wield power but to draw attention away from it.
On those criteria Sarah Palin is one of the most successful Presidents the Multiverse has ever had.
It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework.
No no no. It's generally accepted that each one of these theories taken individually is the best currently known description within its particular domain. It is not generally accepted that you can just throw them together and get an accurate description of the fundamental nature of the universe! In fact, we know you can't do that because general relativity and quantum field theory are deeply incompatible with each other. People have been working for half a century to find a single consistent theory that can reproduce the predictions of both. They've made a lot of progress, but we're still a long way from having any confidence about what the true fundamental theory is.
The picture of eternal inflation described in this article is plausible based on what we know. But it's still very speculative. That's true of any discussion of cosmology. Our current knowledge is just way too limited to have any confidence about it.
"I'm too busy to research this and form an educated opinion, but I do have time to tell everyone my uninformed opinion."
There's that word again. "Heavy." Why are things so heavy in the parallel universe? Is there a problem with the Earth's gravitational pull?