I have to disagree. Just because "results where in 5-space and up you can see and exist in all time simultaneously" appears to be "wacky" doesn't mean it's not possible. It's simply not part of your definition or interpretation of your current existence, which makes the 4th dimension seem out of place.
Again, there's a huge difference between 4D space and 3D spacetime. Both are 4-dimensional mathematical spaces, but the visualization is completely different.
"Time is the fourth dimension" is the single most damaging sentence for your understanding of time and space.
To have an n-dimensional spacetime where time is not the nth dimension makes no sense.
> "Time is the fourth dimension" is the single most damaging sentence for your understanding of time and space.
The video didn't expand on the person living in a 2D space example ... if such of thing would be possible, he would be able to explain the presence of a third dimension using time (going so far as to consider time as being the third dimension).
he would be able to explain the presence of a third dimension using time
NO! Absolutely not! 2D spacetime does not look like 3D space at all!
In 3D space, I can take a 2D angle bracket, flip it in the third dimension, and get its mirror image. This will seem like magic to 2D creatures. In 2D spacetime, I can do no such thing. No matter how long I wait (i.e. move in the third time dimension), the angle bracket won't transform into its mirror image.
In 4D space, I can take a 3D right-hand glove, flip it in the fourth dimension, and get a left-hand glove. This will seem like magic to 3D creatures. In 3D spacetime I can do no such thing. No matter how long I wait, a right-hand glove will never transform into a left-hand glove.
Do you understand?
Do you see how adding time to n-dimensional space does absolutely nothing to explain n+1 space?
That's because dimensions are not ordered. There is no first dimension, or second, or third. For a flatlander, time is what he perceives as a third dimension. Depth may be a fourth dimension. If you wanted to do the same trick to you, you would have to flip yourself in a non-time higher dimensional space. I think any dimensional space would do.
But it's early in the morning and I haven't had breakfast. Talk to you when my brain joins me.
To perceive time as a dimension is useful because it helps you realize you actually perceive four dimensions the same way a flatlander perceives three.
because it helps you realize you actually perceive four dimensions the same way a flatlander perceives three
Absolutely not. We perceive time as time and space as space. The concept of spacetime does not help us understand or visualize higher dimensional spaces at all. It only confuses the issue, which is exactly the original complaint against the video this whole discussion is about.
Edit: One more example: Can you visualize the difference between a 3D cube moving in time, and a 4D cube moving in the 4th dimension? If you project the 4D cube down to 3D, it will look like a double cube that twists itself inside and out, but the 3D cube moving in time will just look like a 3D cube. Spacetime does not help you understanding 4D space.
1) Although videos are visual aids by definition, it wasn't suggesting that a human could visualize any dimension except the 1st, 2nd, and 3rd I believe; this is why mathematicians must use numerical expressions (iterated for the nth time on HN) because human cognition is inextricably tied to interpreting perceptual data within the 3D Cartesian plane. 2) It is a youtube video. 3) Node (n-2) of this one was merely suggesting rather matter-of-factly that confusion is a weak conjecture. 4) I really don't disagree on node (n-1) because any spatial dimension can be parametrized possibly dispelling the "4th" part. I'm assuming your beef is that time breaks down in 5D (or 4D depending on who's counting) because it ceases to move in one direction? 5) If the former is true, Poe's Law still holds, and no matter what, I plea the 5th on further comment of this submission other than god forbid an innocent observe this video and enter into the nth dimension with an error margin of +-D. ;)
I hate to be a spoil sort but the guy that made this doesn't know what he's talking about. He' a musician, not a physicist or mathematician. His proposition fails past the fourth dimension.
I really hate this video. It makes things more complicated than needed.
You can't "visualize" the fourth dimension (or I haven't met anyone who could... and the kind of math/physics where this comes up was a common topic for me for a while).
However, you can understand it pretty easily. Its really just another coordinate. You can do algebra with it. If I say someone is at (3, 2, 5, 6) and moves (1, 2, 3, 4) they are now at (4, 4, 8, 10)...
Want a 5th dimension? Add another comma/number.
People who "visualize" the higher dimensions actually visualize 2 or 3 dimensions and know how to generalize (from practice/experience/theorems).
I think the question that most often comes up is how many dimensions are we living in? And, are all of them equal?
Sure, on paper you can have as many dimensions as you like, just add coordinates, but that won't help us come up with the grand unified theory, or find other new laws of our universe, which might have pretty useful practical applications.
Unfortunately we are limited in seeing beyond our primary senses.
It's like someone in 2d trying to detect 3d, you are presented with a projection and have to extrapolate, but the number of unknowns is, well, unknown.
Its a fair point... sadly I don't know the answer in any great details. What little I know says there are 26 dimensions and they are not all equal. 3 of space, 1 of time, and 22... others...
Actually, I wonder, when people usually ask this question, are they just using the word dimension as a buzz word or do they know what it means?
This is the problem. The 4th dimension is not time. We can represent time as the 4th dimension in a system if we want to, but you can have systems where the 4th dimension is not time.
A good example is when people create a matrix representing links in webpages. If you limit your universe to online 100 webpages and their interconnections, you can get a vector for each webpage. The vector is a point in 100 dimension space. The 4th dimension is not "time" but "if the 4th website on the list links to me."
OK, then I should have worded it like this: I can visualize a 4 dimensional vector space over the reals. Even if the 4th dimension in your particular setting is not time, I can still visualize it as such.
Also, visualizing an n dimensional vector is not very interesting. A vector indicates a point, and a point looks the same in any number of dimensions.
Sure, I suppose visualizing a point is not very interesting. I'm talking about visualizing 4 dimensional space. Can you close your eyes and imagine 4 mutually orthogonal lines?
This is what a physicist friend sent to me a while ago:
"there is really little point in trying to graphically represent anything beyond spacetime. Possibly 3D space with a time vector is useful (i.e. an object representing 3D space moving along a vector) because it is still helpful to explain the concepts. Beyond that just stick with the numbers or you risk confusing yourself on what is being talked about"
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[ 4.2 ms ] story [ 47.8 ms ] threadObligatory link: http://news.ycombinator.com/item?id=1385543
"Time is the fourth dimension" is the single most damaging sentence for your understanding of time and space.
To have an n-dimensional spacetime where time is not the nth dimension makes no sense.
The video didn't expand on the person living in a 2D space example ... if such of thing would be possible, he would be able to explain the presence of a third dimension using time (going so far as to consider time as being the third dimension).
NO! Absolutely not! 2D spacetime does not look like 3D space at all!
In 3D space, I can take a 2D angle bracket, flip it in the third dimension, and get its mirror image. This will seem like magic to 2D creatures. In 2D spacetime, I can do no such thing. No matter how long I wait (i.e. move in the third time dimension), the angle bracket won't transform into its mirror image.
In 4D space, I can take a 3D right-hand glove, flip it in the fourth dimension, and get a left-hand glove. This will seem like magic to 3D creatures. In 3D spacetime I can do no such thing. No matter how long I wait, a right-hand glove will never transform into a left-hand glove.
Do you understand?
Do you see how adding time to n-dimensional space does absolutely nothing to explain n+1 space?
But it's early in the morning and I haven't had breakfast. Talk to you when my brain joins me.
To perceive time as a dimension is useful because it helps you realize you actually perceive four dimensions the same way a flatlander perceives three.
If you want to do space-time calculations, yes.
because it helps you realize you actually perceive four dimensions the same way a flatlander perceives three
Absolutely not. We perceive time as time and space as space. The concept of spacetime does not help us understand or visualize higher dimensional spaces at all. It only confuses the issue, which is exactly the original complaint against the video this whole discussion is about.
Edit: One more example: Can you visualize the difference between a 3D cube moving in time, and a 4D cube moving in the 4th dimension? If you project the 4D cube down to 3D, it will look like a double cube that twists itself inside and out, but the 3D cube moving in time will just look like a 3D cube. Spacetime does not help you understanding 4D space.
You can't "visualize" the fourth dimension (or I haven't met anyone who could... and the kind of math/physics where this comes up was a common topic for me for a while).
However, you can understand it pretty easily. Its really just another coordinate. You can do algebra with it. If I say someone is at (3, 2, 5, 6) and moves (1, 2, 3, 4) they are now at (4, 4, 8, 10)...
Want a 5th dimension? Add another comma/number.
People who "visualize" the higher dimensions actually visualize 2 or 3 dimensions and know how to generalize (from practice/experience/theorems).
Sure, on paper you can have as many dimensions as you like, just add coordinates, but that won't help us come up with the grand unified theory, or find other new laws of our universe, which might have pretty useful practical applications.
Unfortunately we are limited in seeing beyond our primary senses.
It's like someone in 2d trying to detect 3d, you are presented with a projection and have to extrapolate, but the number of unknowns is, well, unknown.
Actually, I wonder, when people usually ask this question, are they just using the word dimension as a buzz word or do they know what it means?
BTW the video is ok until 4:30. Then it quickly degrades into nonsense, not just more complicated than needed.
This is the problem. The 4th dimension is not time. We can represent time as the 4th dimension in a system if we want to, but you can have systems where the 4th dimension is not time.
A good example is when people create a matrix representing links in webpages. If you limit your universe to online 100 webpages and their interconnections, you can get a vector for each webpage. The vector is a point in 100 dimension space. The 4th dimension is not "time" but "if the 4th website on the list links to me."
Also, visualizing an n dimensional vector is not very interesting. A vector indicates a point, and a point looks the same in any number of dimensions.
"there is really little point in trying to graphically represent anything beyond spacetime. Possibly 3D space with a time vector is useful (i.e. an object representing 3D space moving along a vector) because it is still helpful to explain the concepts. Beyond that just stick with the numbers or you risk confusing yourself on what is being talked about"