# Perceiving a 4 dimensional world **URL:** \ **Category:** Factual Questions\ **Created:** [August 10, 2003, 9:40pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257 "2003-08-10T21:40:36Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 10, 2003, 9:40pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/1 "2003-08-10T21:40:36Z")
I find the 3-dimensional world sufficiently complex as it is. Still, it is interesting to think of adding 1 more dimension to it. I once read that to imagine a 4 dimensional world, think of every **point** in 3-dimensional space as a **sphere**. Isn’t that adding too many dimesnsions? Shouldn’t it be stated that you should picture every **point** in 3-D space as a **line**? ---
**Author:** ![Zoe](https://avatars.discourse-cdn.com/v4/letter/z/a4c791/32.png) [@Zoe](https://boards.straightdope.com/u/Zoe)\ **Post date:** [August 10, 2003, 10:00pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/2 "2003-08-10T22:00:46Z")
I remember seeing something on TV about how a four demensional object would make a three demensional shadow. ---
**Author:** ![hlanelee](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@hlanelee](https://boards.straightdope.com/u/hlanelee)\ **Post date:** [August 10, 2003, 10:03pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/3 "2003-08-10T22:03:08Z")
Hey! Think about this! If the glasses they give you at the movies allow you to see three dimensions on a two dimensional plane and you wear them outside, would you see into the fourth dimension?😃 ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [August 10, 2003, 10:06pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/4 "2003-08-10T22:06:44Z")
Humans can’t really see four dimensions. If you think you can, you’re fooling yourself with a projection. All humans can see is three dimensions, so we’d see three-dimensional objects that are `really’ the pieces of four-dimensional objects that happen to share a three-brane with us. To better visualize this, remove a dimension and imagine two-dimensional beings looking at three-dimensional objects. How would a two-dimensional creature see a sphere? As a circle. What kind of circle? The kind of circle that corresponds to the part of the sphere that intrudes upon his two-dimensional membrane (or two-brane, in shorthand). We are just as limited as the two-dimensional beings viewing three-dimensional objects when we try to see four-dimensional objects. ---
**Author:** ![homercles](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@homercles](https://boards.straightdope.com/u/homercles)\ **Post date:** [August 10, 2003, 10:08pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/5 "2003-08-10T22:08:25Z")
Actually, the world is only 3D if you were to take a greyscale snapshot from both eyes. Add time, color, and numerous other dimensions that the visual system readily processes at the level of the cortex and you have a 7 dimensional world–at a minimum. ---
**Author:** ![Scarf-Ace](https://avatars.discourse-cdn.com/v4/letter/s/bc79bd/32.png) [@Scarf-Ace](https://boards.straightdope.com/u/Scarf-Ace)\ **Post date:** [August 10, 2003, 10:09pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/6 "2003-08-10T22:09:12Z")
What does the 4th dimension represent in this model? ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [August 10, 2003, 10:11pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/7 "2003-08-10T22:11:33Z")
**homercles** : No, not correct. In this thread, `dimension' has the standard meaning of `a spatial dimension.’ ---
**Author:** ![Scarf-Ace](https://avatars.discourse-cdn.com/v4/letter/s/bc79bd/32.png) [@Scarf-Ace](https://boards.straightdope.com/u/Scarf-Ace)\ **Post date:** [August 10, 2003, 10:13pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/8 "2003-08-10T22:13:30Z")
Oh that would be time, right? I suppose it does seem a bit strange, but surely you mean “imagine a _mathematical model_ of a 4-dimensional world”? It takes no effort at all to imagine the world as it is. ---
**Author:** ![homercles](https://avatars.discourse-cdn.com/v4/letter/h/ed8c4c/32.png) [@homercles](https://boards.straightdope.com/u/homercles)\ **Post date:** [August 10, 2003, 10:25pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/9 "2003-08-10T22:25:48Z")
> [@](#): > > \*Originally posted by Derleth \* > \*\ ***homercles** : No, not correct. In this thread, `dimension' has the standard meaning of `a spatial dimension.’ \*\* So be it, i suppose i may not have read the OP very closely. BTW, youre in Havre, Montana? I was born in Harlem. Part of the Walsh clan. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [August 10, 2003, 11:48pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/10 "2003-08-10T23:48:32Z")
**Meta-Gumble** : As I said, in this thread, I think the OP is referring to a fourth _spatial_ dimension, not a _timelike_ dimension. There’s no such thing as _the_ fourth dimension, just various mathematical models that call up different numbers of dimensions, spatial and timelike, to explain what we observe. To use an oft-referenced example, string theory implies _eleven_ spatial dimensions in its equations, and not one of those eleven can be equated with time. **homercles** : Not familiar with the Walsh clan, but I do live close to Harlem. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [August 10, 2003, 11:53pm UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/11 "2003-08-10T23:53:11Z")
> [@](#): > > \*Originally posted by wolf\_meister \* > I once read that to imagine a 4 dimensional world, think of every **point** in 3-dimensional space as a **sphere**. > Isn’t that adding too many dimesnsions? > > Shouldn’t it be stated that you should picture every **point** in 3-D space as a **line**? There’s no one best way to visualize 4-D, and I’ve yet to be convinced that anyone can. However, thinking of a 4-D point as a 3-D sphere is not necessarily bad off. A 3-D point requires three “dimensional values” to describe it: x, y, and z, if you like. Similarly, a 4-D point requires four. A 3-D sphere also requires four: x, y, z, and R. Although it’s crude, you can think of “point size” as the fourth dimension to help you visualize. For instance, you can imagine [a line going from point A to point B](http://www.fractal-landscapes.co.uk/graphics/pictures/spheres.jpg), and as it went along, [the “points” got bigger](http://www.btinternet.com/~d.macauley/spheres.jpg), so that you had small spheres at point A and big spheres at point B. This is sort of like a line in 4-D. ---
**Author:** ![SPOOFE](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@SPOOFE](https://boards.straightdope.com/u/SPOOFE)\ **Post date:** [August 11, 2003, 12:47am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/12 "2003-08-11T00:47:04Z")
Can’t visualize 4 dimensions? What are you talking about? There’s an entire generation of people that can see 4 dimensions. They’re the ones that took all the LSD back in the '60s. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [August 11, 2003, 1:24am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/13 "2003-08-11T01:24:29Z")
Okay, thanks for all of your replies. And yes I was talking about a spatial 4th dimension. Achernar I like your explanation of “point size” being a sphere in the 4th dimension. ---
**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\ **Post date:** [August 11, 2003, 1:50am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/14 "2003-08-11T01:50:19Z")
I too learned (many years ago) that time, the passage of time anyway, was a fourth dimension. My information _is_ pretty old, though. Probably 30-40 years. I read about it, but can’t remember what or by whom. The same article claimed the impossibility of only two (spacial) dimensions. Four dimensions (x,y,z,t) or oblivion, take your pick. 😉 Peace, mangeorge ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [August 11, 2003, 2:46am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/15 "2003-08-11T02:46:12Z")
**mangeorge** : Well, time is a timelike dimension, and therefore different from a spatial dimension. For example, information can only travel in the time dimension in one direction, and entropy is directional only in the time dimension. In a fourth spatial dimension, information could travel it both directions and entropy wouldn’t exibit any tendancies along it. ---
**Author:** ![Johanna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johanna/32/8318_2.png) [@Johanna](https://boards.straightdope.com/u/Johanna)\ **Post date:** [August 11, 2003, 7:15am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/16 "2003-08-11T07:15:07Z")
I can perceive a 5-dimensional world every time I listen to “Age of Aquarius” or “Up, Up and Away.” 😉 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 11, 2003, 7:26am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/17 "2003-08-11T07:26:43Z")
\ Consider: A zero-dimensional _point_, extruded through one dimension describes a one-dimensional _line_. A one-dimensional _line_, extruded through a second dimension (perpendicular to the first) describes a two-dimensional plane _square_. A two-dimensional _plane square_, extruded through a third dimension (perpendicular to the other two) describes a three-dimensional solid _cube_. A three-dimensional _silod cube_, extruded through a fourth dimension (perpendicular to the other tthree) describes a four-dimensional 'hyper’solid _Metacube_. Trouble is that is is very difficult to visualise the fourth extrusion; usually, the mind’s eye will see it as an extrusion in some vector composed of the existing three dimensions. Another thing: To a resident of a two-dimensional universe (Flatland), a one-dimensional line is visible in full - the resident of the one-dimensional universe (Lineland) can only observe the points on the line adjacent to his own position. To a resident of a three-dimensional universe (Spaceland), a two-dimensional plane figure is visible in full - the resident of the two-dimensional universe (Flatland) can only observe the sides facing to his own position. To a resident of a four-dimensional universe (Hyperland), a three-dimensional solid figure is visible in full - the resident of the three-dimensional universe (Spaceland) can only observe the faces presented toward to his own position. - From a vantage point in the fourth spatial dimension, all six faces of a three-dimensional cube would be visible at the same time. ---
**Author:** ![EllisDee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellisdee/32/4531_2.png) [@EllisDee](https://boards.straightdope.com/u/EllisDee)\ **Post date:** [August 11, 2003, 7:27am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/18 "2003-08-11T07:27:31Z")
I always felt like we see the world in two dimensions, and our brains interpret the depth aspect. A 2D person would NOT see a sphere as a circle. That would require being “above” the plane to see the entire circle. (Flatland is a good book for this concept.) A sphere would appear as a line that got “fuzzy” toward the edges. In much the same way as a 3D object (sphere) appears to a 2D creature as a 1D object (line), we see the world in 2D and “interpret” the third. Just my $0.02. (Hmmm…is this IMHO or GQ?) ---
**Author:** ![EllisDee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellisdee/32/4531_2.png) [@EllisDee](https://boards.straightdope.com/u/EllisDee)\ **Post date:** [August 11, 2003, 7:29am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/19 "2003-08-11T07:29:23Z")
Damn Mangetout, you beat me to the simulpost. You win the Flatland reference race. But I’ll be back, I tell ya! ---
**Author:** ![jovan](https://avatars.discourse-cdn.com/v4/letter/j/0ea827/32.png) [@jovan](https://boards.straightdope.com/u/jovan)\ **Post date:** [August 11, 2003, 8:17am UTC](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257/20 "2003-08-11T08:17:25Z")
Damn, both **Ellis Dee** and **Mangetout** beat me to it. Damn you all! Every single both of you! Seriously, you should read the actual [Flatland book](http://www.amazon.com/exec/obidos/ASIN/048627263X/qid=1060590145/sr=2-1/ref=sr_2_1/002-4542286-6375238), it’s dirt cheap and, well, just plain weird. [Next page](https://boards.straightdope.com/t/perceiving-a-4-dimensional-world/194257.md?page=2)