How do scientist know 12 dimensions exist? And why 12, why not 7... or 17?

answers:
busterwasmycat say: Which model of reality do you accept? The "12" idea is just the number of basic fundamental parameters that need to be considered to provide a functional mathematical description of reality. Dimensions are just a word we use to describe a variable (like length). When you calculate a volume, you require 3 dimensions, length, width, height. You can play around with measurement systems and use angles instead (polar coordinates) so the actual "dimensions" would be different, but you still need three. So twelve is what one model suggests is the minimum necessary number of factors that must be considered to fully describe the way things are.
It is an open discussion whether the models are "correct". The details of the arguments are beyond my knowledge level. The "why" part is actually interesting in a way, not in the sense of why do they think 12, but why would a universe be able to exist, to be, with precisely 12. What is it about reality that makes it need 12 only functional parameters to make everything be what it is (or whatever number turns out to be correct)? There must be some set of fundamental factors that allow everything to be what it is, but the number is something we have to figure out. It is not an inherently obvious aspect of reality.

Philomel say: They don't Know any of it, they theorize It. This means it is imaginary. The imagination of a genius is still imagination.

Andrew Smith say: This is a pointless description.
Two things are different if they differ in ANY dimension.
a different value of x or y or z or time means that an object is not the same.
But what about a red object versus a blue object.
If they had all the same other four dimensions can you tell the difference between red and blue?
But we accept colour as having three components.
Something is different if it has a different charge.
And so on.
We can call something a dimension if it meets the first criteria at the top.
Hence there may be more or less dimensions depending on how well it suits us to consider the properties.

sepia say: According to superstring theory, there are at least 10 dimensions in the universe (Mtheory actually suggests that there are 11 dimensions to spacetime; bosonic string theories suggest 26 dimensions). That’s a bit of a mindboggler: Most people understand the basic three dimensions, and many know that the fourth dimension is probably time.

neb say: The idea that the universe has 11 dimensions comes from a theory called mtheory which is a glorified version of string theory. So, it is the theory itself that requires 11 dimensions, and since the theory is not proven, we do NOT know that the universe has 11 dimensions.
Mtheory is an extraordinarily complex theory. It is based on a concepts called branes which are the basic components of reality in the theory. The branes can have a variable number of dimensions, and are embedded in the spacetime of 11 dimensions. A 1brane is a one dimensional string (from string theory), a 3brane is our universe, etc.
The reason for the number of dimensions is that the theory has to be internally consistent (it also requires supersymmetry) and since particles are represent by strings, the vibrational modes of the strings require this number of dimensions to explain all of the physical properties of particles.
While mtheory is in serious trouble because of the failure of the LHC to find evidence of supersymmetry, you have to admire a theory that does not assume that our 4d spacetime is just a random given, but that the dimensions of nature are driven by the requirements of physical laws.

Tom S say: They don't. There are different theories that require different numbers of dimensions. I have not run across 12, but 10, 11 and 26 are popular numbers. I certainly don't know which if any of the theories are correct.
From: https://en.wikipedia.org/wiki/String_the...
"In bosonic string theory, spacetime is 26dimensional, while in superstring theory it is 10dimensional, and in Mtheory it is 11dimensional."

Chris say: Mandela effects have exactly twelve variations.

Lord Bacon say: I wasn't aware of the number of dimensions currently believed to be true but I was aware that the existence of additional dimensions had been calculated to be the case and would explain the anomalies observed in the universe.
Humans are dimensionally challenged in that we are aware only of three spacial dimensions plus time. It is possible to imagine another dimension in which all our spatial dimensions are folded into a single point. What we can't imagine is what experience of other dimensions would be like. That doesn't stop mathematicians being able to model multidimensional universes using robust mathematical methods.
I am not clever enough to understand the advanced mathematics involved but I hope, some day, they will find a way of communicating the evidence to ordinary people in a form we can understand.

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