(Dec 23, 2020 04:57 PM)Ostronomos Wrote: [...] Many-worlds was the competing theory to wavefunction collapse within the Copenhagen interpretation if I'm not mistaken. What is said about higher-dimensional string theory? That universes interfere under wavefunction interference?
A "multiverse" also arises in several other background theory scenarios, not just the Everett interpretation.
Refinements and offshoots of string theory produced the idea that our universe is one among many, each confined to a brane, and it's those branes that would potentially collide or interact with, or influence this universe.{1} But string theory is becoming passé, regarded as a fail, apart from the mathematics it introduced. Cosmological inflation (minus string theory), on the other hand, has legs and is widely accepted.{2}
Excerpt from footnote-2: "
The fabric of the multiverse is an inflationary field that's filled with quantum fluctuations. These fluctuations can interfere with each other, creating high inflation at the peaks. The low points of the interference are where stable universes can pop out of the field. Conveniently, the high points continue to inflate, producing more multiverse fabric, which undergoes its own quantum fluctuation, making it an endless producer of universes; Andrei Linde describes it as a fractal process."
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Many Interacting Worlds: Physicists Propose Existence, Interaction of Parallel Universes
http://www.sci-news.com/physics/science-...02249.html
EXCERPT: . . . According to the team, their model of such a ‘many interacting worlds’ approach can reproduce some quantum phenomena – such as
Ehrenfest’s theorem, wave packet spreading, barrier tunneling, and zero-point energy – as a direct consequence of mutual repulsion between parallel worlds.
“This picture is all that is needed to explain bizarre quantum effects such as particles that tunnel through solid barriers and wave behavior in double-slit experiments.”
Dr Michael Hall of Griffith University, the first author
of the paper, said: “the ‘Many-Interacting Worlds’ approach may even create the extraordinary possibility of testing for the existence of other worlds. The beauty of our approach is that if there is just one world our theory reduces to Newtonian mechanics, while if there is a gigantic number of worlds it reproduces quantum mechanics. In between it predicts something new that is neither Newton’s theory nor quantum theory.”
“We also believe that, in providing a new mental picture of quantum effects, it will be useful in planning experiments to test and exploit quantum phenomena.” (
MORE - details)
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{1}
The theory of parallel universes is not just maths – it is science that can be tested: ... due to the quantum fluctuations of space-time, some parts of the universe never actually reach the end state of
inflation. This means that the universe is, at least according to our current understanding, eternally inflating. Some parts can therefore end up becoming other universes, which could become other universes etc. This mechanism generates a infinite number of universes.
By combining this scenario with string theory [...] the universes predicted by string theory and inflation live in the same physical space (unlike the many universes of quantum mechanics which live in a mathematical space),
they can overlap or collide. Indeed, they inevitably must collide, leaving possible signatures in the cosmic sky which we can try to search for... (
MORE - details)
{2}
Manufacturing universes in a fractal multiverse: To understand the multiverse, you've got to understand
inflation, and for that, the panel had Alan Guth, who was instrumental in developing it as a concept. The basic idea of inflation is that, early in the Universe's history, it went through a period where it expanded at a staggering rate...
[...] Another panelist, Andrei Linde of Stanford ... was working on inflation from the perspective of what's called the "graceful exit" problem: how do you get inflation that's just enough to blow up the Universe, but stops before ripping it apart? The answer Linde eventually came up with is that sometimes you do, sometimes you don't. This is where the idea of a multiverse comes in.
The fabric of the multiverse is an inflationary field that's filled with quantum fluctuations. These fluctuations can interfere with each other, creating high inflation at the peaks.
The low points of the interference are where stable universes can pop out of the field. Conveniently, the high points continue to inflate, producing more multiverse fabric, which undergoes its own quantum fluctuation, making it an endless producer of universes; Linde describes it as a fractal process.
Festival founder Brian Greene was on hand to mention why, as a string theorist, the multiverse was very satisfying to him. In short, string theory has been suffering from its own inflation, as it looks like there are 10 or 11 extra dimensions beyond the four familiar ones of space-time. How those extra dimensions get compacted away determines the physical properties of our Universe. Over a decade ago, Greene was hoping something would come out of the math that would explain why we have the properties we do, but now he accepts that we're living in a universe with just one out of over 10^500 potential combinations of properties.
The nice thing about the multiverse is that each of the universes it spews out should have its own set of physical rules. So, in short, if the process really is infinite, a universe with our properties was pretty much inevitable. In fact, something with a value for dark energy that's similar to our own universe appears in somewhere around 10^300 of the possible types of physics predicted by string theory.
Dec 23, 2020 04:57 PM
(This post was last modified: Dec 23, 2020 05:03 PM by Ostronomos.)
