Extra Dimensions
the post had a link to a video: Lisa Randall  Are There Extra Dimensions?
It began with the question  how can we begin to understand the concept of extra dimensions? She began with the flatland story where their universe was limited to 2 dimensions.
my comment:
Such gobbledygook about dimensions! The flatland story is a good example of the confusion.
Nothing exists in any number of dimensions.
Anyone who took geometry in their early education knows dimensions are used to describe positions, like plotting results of equations of the variables (like x vs y vs z). The observer can describe any number of dimensions each with its own origin and scaling. The observer can also define a coordinate system to describe positions of objects in space.
The Euclidean geometry is intuitive, just left/right, up/down, in/out.
The story of flatlanders limited to only 2 dimensions is silly and entertaining but not real. Any flatlander could (if allowed) take a geometry course and realize they decide the number of dimensions they wish to use. Apparently flatlanders are fools and they agree on silly rules.
The universe has no builtin dimensions. We chose to agree on our 4 with 3 linear coordinates and 1 time coordinate. If my research involves temperature then I can freely add another dimension for temperature where I pick the scaling (C or F). I am not creating a universe of higher dimensions (5!!) unless I enjoy such hyperbole.
In cosmology there are innumerable values to plot along with celestial coordinates, such as distance, magnitude, object type, etc.
Contrary to this silly video we do not live in a 4D world though some are inclined to believe in that false restriction.
There are no extra dimensions. Any extra are those I had not defined. There are no predefined dimensions laying about for me to forget to add to my set, as if the dimensions are individual objects. One might as well say there are infinite dimensions in the universe (or an unlimited capacity) but I have yet to have a need for more than 4 to deal with all my observations. There are no higher dimensions.
I agree with one statement in the video. They don't understand 3 dimensions,
As an observer of string theory behaviors one can define as many dimensions as required. They are defining their coordinate system for their observations. If someone working with string theory claims they are working in a higher dimensional universe they are just delusional.
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