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I agree with some of what you say in that introducing theories for which there is absolutely no known evidence doesn't exactly help their credibility. However:

I agree with some of what you say in that introducing theories for which there is absolutely no known evidence doesn't exactly help their credibility. However: > A "dimension" is an axis, not a universe, I don't think you should be so absolutest about that. How do you know that what we think of as "the universe" doesn't live entirely in a 3+1 dimensional subspace of some larger universe ?

andrewflnr 7y ago
I don't know that our universe isn't a subspace of some higher-dimensional structure. That has nothing to do with what the specific word "dimension" means and has always meant outside of sci-fi. There has never been a sound reason to use the word "dimension" to describe the other possibilities you mention. If you want to write a technical document about those possibilities and be taken seriously, you need to find a better term. Invent one if necessary.
- tgflynn 7y ago
  In that case I think it's you who is misunderstanding the word. Unfortunately I haven't the time to give you a course on Linear Algebra so unless you can explain in more detail why you believe that the word "dimension" is inappropriate for the case I described I'm not going to be able to help you. I do suggest you watch this video from Carl Sagan's TV show Cosmos: https://www.youtube.com/watch?v=N0WjV6MmCyM https://www.youtube.com/watch?v=N0WjV6MmCyM
  - andrewflnr 7y ago
    Linear algebra is exactly where "dimension" gets its abstract but very limited definition as a property of spaces, best summarized as an axis or direction, rather than a kind of space itself, which is what you need for anything like an alternate universe. I know this because I have in fact taken a course in it. I'm not sure what point you think you're making at this point.
    - tgflynn 7y ago
      > Linear algebra is exactly where "dimension" gets its abstract but very limited definition as a property of spaces, best summarized as an axis or direction, rather than a kind of space itself Yes, but adding an extra dimension to a given space (more correctly stated as asserting that a space of dimension d is embedded in a space of dimension d + 1) vastly expands the "number" of points that are available, so adding a dimension doesn't just give you access to an additional d-space but to a whole continuum of other d-spaces. I think this is what people are referring to when they use the word "dimension" in this kind of context.
      - andrewflnr 7y ago
        Most people have no such precise idea when they talk about "dimensions". Those who do would, when pressed, admit that even if you could be said to travel through or along some other dimension to reach another world, or even an infinity of other worlds, said dimension is not the same as those worlds, just a term for a relationship between them. Moreover, I don't care about what people think they're saying with their crap terminology. I demand actual accuracy, or at minimum precisely delimited uncertainty, from people taking millions of dollars in government funding to write about aliens. This is not too much to ask. (You do remember the context, right? Evaluating the credibility of a purportedly factual report written under a government contract, not a bar debate about cosmology)

andrewflnr 7y ago

I don't know that our universe isn't a subspace of some higher-dimensional structure. That has nothing to do with what the specific word "dimension" means and has always meant outside of sci-fi. There has never been a sound reason to use the word "dimension" to describe the other possibilities you mention. If you want to write a technical document about those possibilities and be taken seriously, you need to find a better term. Invent one if necessary.

tgflynn 7y ago
In that case I think it's you who is misunderstanding the word. Unfortunately I haven't the time to give you a course on Linear Algebra so unless you can explain in more detail why you believe that the word "dimension" is inappropriate for the case I described I'm not going to be able to help you. I do suggest you watch this video from Carl Sagan's TV show Cosmos: https://www.youtube.com/watch?v=N0WjV6MmCyM https://www.youtube.com/watch?v=N0WjV6MmCyM
- andrewflnr 7y ago
  Linear algebra is exactly where "dimension" gets its abstract but very limited definition as a property of spaces, best summarized as an axis or direction, rather than a kind of space itself, which is what you need for anything like an alternate universe. I know this because I have in fact taken a course in it. I'm not sure what point you think you're making at this point.
  - tgflynn 7y ago
    > Linear algebra is exactly where "dimension" gets its abstract but very limited definition as a property of spaces, best summarized as an axis or direction, rather than a kind of space itself Yes, but adding an extra dimension to a given space (more correctly stated as asserting that a space of dimension d is embedded in a space of dimension d + 1) vastly expands the "number" of points that are available, so adding a dimension doesn't just give you access to an additional d-space but to a whole continuum of other d-spaces. I think this is what people are referring to when they use the word "dimension" in this kind of context.
    - andrewflnr 7y ago
      Most people have no such precise idea when they talk about "dimensions". Those who do would, when pressed, admit that even if you could be said to travel through or along some other dimension to reach another world, or even an infinity of other worlds, said dimension is not the same as those worlds, just a term for a relationship between them. Moreover, I don't care about what people think they're saying with their crap terminology. I demand actual accuracy, or at minimum precisely delimited uncertainty, from people taking millions of dollars in government funding to write about aliens. This is not too much to ask. (You do remember the context, right? Evaluating the credibility of a purportedly factual report written under a government contract, not a bar debate about cosmology)