3 ms·

> That is simply a solid with a time value in > the future, which is the same four dimensions > as the preceding example. My train of thought (not to s

> That is simply a solid with a time value in > the future, which is the same four dimensions > as the preceding example. My train of thought (not to say it's original) is: You can't move a solid without another (a fifth) dimension (ie: time). You can't move the trail of solids that exist in time without a second dimension of time (the sixth, if we're counting all the way up from a 1D point). If you have two sequences of events that are slightly different (side by side, ignoring that a "side" is a 4D side, I guess), that "timeline" which differs from the original is a "possible universe".

uniqueid 6y ago
My numbering was off. 4th is time. 5th adds the direction going between one universe and a variation of it, both at the same point on the time axis. I also notice in my example I start with zero dimensions. All in all, a reminder that I should exercise more self-restraint and not comment on Physics articles :D
jerf 6y ago
The problem here is that you've got a subset/superset relationship reversed. "Dimension" is simply the need to add a number to fully describe a system, as I gave in the several examples. It is true that if there was some system of parallel universes that a number identifying the universe could be necessary to fully identify the location of an object. (Depending on the nature of the multiple universes, it could even require more than one.) But "identifying which universe something is in" is not the definition of "the fifth dimension". It is simply a particular instance/subset of the general concept of dimension, which happens to also be currently meaningless and without referent. But even so, it manages to screw people up and provide significant cognitive interference for the real concept of dimensionality, which is, as I said, much less "woo woo", which may be sort of disappointing, but also a much richer concept that provides much more to explore, because it actually has content to it. You can also see the confusion in the miscounting of dimensions, because they are not being thought of as simply numbers that identify a place/thing, but some sort of ordered list of "concepts", where "things that don't exist yet" are somehow in another "dimension". But as I said, you don't need another "dimension" for that; it's just a time coordinate, which we already have, in the future. This is the sort of thing that drives me to post this point. It's a surprisingly popular viewpoint. There's a YouTube video that does this sort of thing, which got very popular, and I don't even want to link to, because it's a steaming pile of garbage, leaving viewers who watch it feeling like they understand better when in fact they understand far worse. It's not necessarily in the top ten list of "ideas that will prevent you from understanding the world better" or anything, but it's certainly on that list.
- uniqueid 6y ago
  > But "identifying which universe something is in" > is not the definition of "the fifth dimension". Is there a difference? Lets say we have a bunch of film strips, laid one on top of another, only each frame represents an entire 3D universe, and each layer of a new film strip, at the same point from the start, becomes less similar* as you move from layer to layer. To identify where something is, you would refer to the delta (ie: of the number of layers). That was what I was getting at. *Hand-waving to ignore that in real life, each frame probably spawns multiple children, but only has one parent.
  - jerf 6y ago
    It is a dimension, in your hypothetical example with no known real-world correspondance. It is not the fifth dimension. "The" fifth dimension is a scifi concept, not a real one. Perfectly normal, mundane reality contains numerous instances of much higher dimensionality. Which of the subcolors of the pixels on your screen is "the" fifth dimension? Dimensionality isn't "about" parallel universes. It is a very tiny, and really quite useless, instance of the concept, which is full of useful and interesting members that actually, you know, exist.
    - uniqueid 6y ago
      > "The" fifth dimension is a scifi concept, > not a real one. I'm confused now. How Is it possible for a dimension to "not be real" when a dimension is just a way to relate multiple points together? Unless you run out of points, can't you describe their relation using as many dimensions as you need? Maybe our communication is breaking down over the term "parallel universe". I don't mean it as a sci-fi thing, I mean it as a Schrödinger's cat thing. Without possible universes, we can't explain our intuition that an event can have multiple outcomes. Why should one of them happen, and not the others? With possible universes, there's no problem, because they all happen. How would one describe the relation of where they happen without a dimension higher than time? I don't mean a parallel universe as some fantastical place that we could "visit" etc.

uniqueid 6y ago

My numbering was off. 4th is time. 5th adds the direction going between one universe and a variation of it, both at the same point on the time axis. I also notice in my example I start with zero dimensions. All in all, a reminder that I should exercise more self-restraint and not comment on Physics articles :D

jerf 6y ago

The problem here is that you've got a subset/superset relationship reversed. "Dimension" is simply the need to add a number to fully describe a system, as I gave in the several examples. It is true that if there was some system of parallel universes that a number identifying the universe could be necessary to fully identify the location of an object. (Depending on the nature of the multiple universes, it could even require more than one.) But "identifying which universe something is in" is not the definition of "the fifth dimension". It is simply a particular instance/subset of the general concept of dimension, which happens to also be currently meaningless and without referent. But even so, it manages to screw people up and provide significant cognitive interference for the real concept of dimensionality, which is, as I said, much less "woo woo", which may be sort of disappointing, but also a much richer concept that provides much more to explore, because it actually has content to it. You can also see the confusion in the miscounting of dimensions, because they are not being thought of as simply numbers that identify a place/thing, but some sort of ordered list of "concepts", where "things that don't exist yet" are somehow in another "dimension". But as I said, you don't need another "dimension" for that; it's just a time coordinate, which we already have, in the future. This is the sort of thing that drives me to post this point. It's a surprisingly popular viewpoint. There's a YouTube video that does this sort of thing, which got very popular, and I don't even want to link to, because it's a steaming pile of garbage, leaving viewers who watch it feeling like they understand better when in fact they understand far worse. It's not necessarily in the top ten list of "ideas that will prevent you from understanding the world better" or anything, but it's certainly on that list.

uniqueid 6y ago
> But "identifying which universe something is in" > is not the definition of "the fifth dimension". Is there a difference? Lets say we have a bunch of film strips, laid one on top of another, only each frame represents an entire 3D universe, and each layer of a new film strip, at the same point from the start, becomes less similar* as you move from layer to layer. To identify where something is, you would refer to the delta (ie: of the number of layers). That was what I was getting at. *Hand-waving to ignore that in real life, each frame probably spawns multiple children, but only has one parent.
- jerf 6y ago
  It is a dimension, in your hypothetical example with no known real-world correspondance. It is not the fifth dimension. "The" fifth dimension is a scifi concept, not a real one. Perfectly normal, mundane reality contains numerous instances of much higher dimensionality. Which of the subcolors of the pixels on your screen is "the" fifth dimension? Dimensionality isn't "about" parallel universes. It is a very tiny, and really quite useless, instance of the concept, which is full of useful and interesting members that actually, you know, exist.
  - uniqueid 6y ago
    > "The" fifth dimension is a scifi concept, > not a real one. I'm confused now. How Is it possible for a dimension to "not be real" when a dimension is just a way to relate multiple points together? Unless you run out of points, can't you describe their relation using as many dimensions as you need? Maybe our communication is breaking down over the term "parallel universe". I don't mean it as a sci-fi thing, I mean it as a Schrödinger's cat thing. Without possible universes, we can't explain our intuition that an event can have multiple outcomes. Why should one of them happen, and not the others? With possible universes, there's no problem, because they all happen. How would one describe the relation of where they happen without a dimension higher than time? I don't mean a parallel universe as some fantastical place that we could "visit" etc.