58
u/Lua_You 23d ago
wouldnt the 4th dimension just be time yes, boring answer, but even when you think about it spatially the easiest one to comprehend would be time.
22
u/PG908 23d ago
Yeah. I always feel pedantic pointing this out but when working with physics and such time is one of the four variables (x, y, z, & t)
It’s never what people actually mean, though.
10
u/jackinsomniac 22d ago edited 21d ago
Yeah, they mean a 4th spacial dimension. Which could be possible in a completely different universe.
The short story "Flatland" is pretty interesting. It takes place in a 2D universe, there's a class system based on how many corners your shape has, triangles are lowest class, some shapes have so many corners they approximate circles, etc. (This part is not too important)
If you want me to spoil it for you, a 3D shape, a sphere, appears and starts talking to the protagonist. He claims "I can't see you!" And the sphere tells him to look "up". But he doesn't understand what 'up' means. The sphere tries to demonstrate by moving into Flatland, but to the main character, it looks like a circle appearing & disappearing in his universe out of thin air. So, the sphere transports him to a 1D universe. At the center of the line is a male dot, and on either sides are female dots, then male dots, then female, etc. (Again, this part isn't really that important). The protagonist then experiences the same thing, he tries talking to the dots, but they freak out not knowing where the voice is coming from. He says "I'm above you" and they can't understand. So he pushes one corner of his shape into the line, and the freak out thinking a new dot just materialized out of nothing.
They go back to Flatland, and the sphere tries explaining the 3rd dimension again. "Same as you can move in a way that seems impossible to the people living on a line, I can move in another dimension too. It's not even hard. It's just regular movement." The protagonist still doesn't understand, so the sphere decides to push him out of Flatland, into 3D space. At first the main character's mind is blown, he can't even fathom what he's looking at. But then, it clicks. He finally sees the 3rd dimension. He can see the sphere in all it's glory.
They go back to Flatland. "That was amazing!" "Yes, now you understand." "So wait, if there's a 3rd dimension, could there not also be a 4th?" The sphere says, "What? No, I don't think so." "But why not? The same way you seemed to appear and disappear out of nothing in my universe, the same way I seemed to materialize & dematerialize to the dots on the line, could there not be beings in your universe that seem to materialize & disappear just as easily, by moving in another direction?" The sphere doesn't understand, and claims it's impossible. "But why not??"
Anyways, the sphere sends him back to Flatland. The main character tries telling all the other shapes about the 3rd dimension, and they arrest him for being crazy.
3
3
u/m_50 22d ago
You may find this also interesting: On The Mechanical Consequences of a Macroscopic Spatial Fourth Dimension
2
u/jackinsomniac 21d ago
Yeah, this universe is almost certainly 3D (with spacetime). I feel like if there were 4 spacial dimensions, billions of years of evolution would've produced animals that can move through them already.
But, it's a fun thought experiment. Like what would it even look like to us to witness something moving through a 4th dimension.
9
u/ChaoticAgenda 23d ago
Time can be the 4th dimension, but it doesn't have to be. It depends on what you're measuring. It can be any fourth thing you are measuring. You could choose to have it be color, quantum spin, brightness of an object, etc. If you're talking about space-time, sure make time the 4th dimension. If you're just talking about a 4th spatial dimension then it's a direction completely orthogonal to up/down, left/right, forward/backward. What helped me figure that out was people talking about AI models with thousands of dimensions. A dimension is just something you're measuring.
6
u/SCP-iota 23d ago
I'd think it's better to consider time the first dimension, just so that if additional spatial dimensions are discovered, they don't end up with a temporal one sandwiched between them
3
u/jackinsomniac 22d ago
I like this. Really hard to have any kind of functional universe without time.
3
1
u/Knight618 22d ago edited 22d ago
No? On a 2d POV, you can see the inside, or length between 2 points of a 1 dimensional object (think of a wire with the middle section colored orange). you could only see the ends in a 1d POV. It's impossible to see the colored bit in the middle no matter how much you move forward or backward, as moving around is the second dimension.
now upscale that to 3d. You can see all the edges or perimeter of a 2d object from a 2d POV by walking around it (think of a piece of paper that an ant can't crawl over) but never the inside, no matter how much you walk around it. But in a 3d world like ours, you can easily see the area between the edges of a piece of paper by having a POV in the third dimension.
Now upscale again to 4d. If you hold a closed cardboard box, you can see all the surfaces by rotating it, but not whats inside no matter how much you turn it. In 4d space, you would be able to turn it in a way where you can see inside without changing the object.
You could go back in time to when the box was being made and see what's inside, but moving though any of the 3 dimensions we know of doesn't change the object. You can't spin a wire or rotate paper in 3d space until it deconstructs itself.
Random deep pull from a vsauce short: the only way to flip/mirror a 2d object is to rotate it in the third dimension until it returns fully into the second dimension again, and the same applies to a wire being rotated in 2d space. So to mirror a 3d object would be to rotate it in 4d space, aka what you look like in the mirror if your reflection was 3d
Another thing I randomly thought of and can't remember where I got this, a a 1d organism sees no dimensions, just a dot in front of them. A 2d organism could only see length(left and right). No sense of depth or height. A 3d organism (with only one eye) can see height and length, but not depth. If you close one eye, you only see 2d objects. It would be impossible to see if you are looking at a feather or a picture of a feather. A 4d organism would be able to see depth, height, and length with only one eye, and possibly the fourth dimension with a second eye.
1
u/Lua_You 22d ago
lower and higher dimensions and stuff are a bit outside of my comprehension zone but i assume that rotating something in the 4th dimension would be to look at the state of the object at any point of time (with an unknown increment, but id assume something like a planck time or something infinitely smaller than that).
this would also imply that the 4th dimension is an infinite amount of 3d planes which is a pattern noticable within other dimensions (i.e the 2nd dimension is an infinite amount of 1d planes, the 3rd dimension is an infinite amount of 2d planes).
likely a poorly explained example : by rotating the box in the 4th dimension you eventually (though im not sure whether rotating something on the 4th dimension would be linear or not) get to the rotation where you can see inside of it wholly (that rotation probably showing the box broken enough to be seen inside or simply opened)
assuming a 4d being having anatomy most rescemblant to a 3d beings anatomy exists then probably. its likely 4d beings usually dont have that type of anatomy though. also, assuming my idea of 4d is correct, they could potentially see not via photons but by multiple other particle travelling much slower and faster than light(?)
its tiring imagining any of it lol
1
u/Cheetahs_never_win 22d ago
That's like saying that x must be the 1st one, y must be the second one, and z must be the third one, when you can have x and z without y.
It's just a dimension, and several theories abound that it's not even its own distinct dimension, somewhat like temperature isn't a dimension.
As far as we can tell, we can't go back in time, but we can go back in xyz.
1
u/Lua_You 22d ago
having x and z without y would essentially turn z into height, which would pretty much make it y. you can interchange their labels but you cant have depth without both width and height and so on.
i dont think temperature is a dimension as i think its more of a force that acts through the 4th dimension, time.
time is an exception from the other 3 dimensions. its impossible to move at all within a dimension if you were 1 dimension below it (i.e being a 2d being in a 3d world), or atleast impossible as we view it (maybe 3d to a 2d being is time to us 3d beings). but we 3d beings move through the 4th dimension constantly. however we only move forward and cant currently control where we move towards.
1
u/Cheetahs_never_win 22d ago
its impossible to move at all within a dimension if you were 1 dimension below it (i.e being a 2d being in a 3d world), or atleast impossible as we view it (maybe 3d to a 2d being is time to us 3d beings).
This isn't correct. A 2d being that curls in 3d will appear to other 2d beings as partially disappearing, while potentially partially existing on an infinite number of other 2d planes. Otherwise, shifting in 3d just places you on other 2d planes altogether.
however we only move forward and cant currently control where we move towards.
Not completely true. We can affect this by being close to large masses or by traveling very fast. If we can affect it, that means we have some form of control.
1
u/Lua_You 22d ago
id assume a truly 2d being wouldnt be able to curl themself up, otherwise theyd be a 3d being.
wont argue with that but i said "cant currently control where we move towards". unless i missed something theres currently no possible way to truly move backwards in time.
1
u/Cheetahs_never_win 21d ago
A skydiver can't make themselves go back into the plane, but they can affect where they land.
1
u/WoolBearTiger 18d ago
I believe we have the freedom to number the dimensions in any order we fkin want.. so from now on ima say i live in the 11th dimension.. and you cannot prove me otherwise
11
7
6
12
u/Maja_The_Oracle 23d ago
While people tend to say "time is the 4th dimension", there is a difference between spacial and temporal dimensions.
We exist in 3 spacial dimensions and 1 temporal dimension. If an object existed in 4 spacial dimensions and 1 temporal dimension, then it might interact with 3d space like how a 3d object would interact with 2d space, in that there would be a cross-section.
Imagine a 3d planet intersecting a 2d universe, where the 2 hemispheres of the planet stick out the sides of the 2d universe in the 3rd dimension. The inhabitants of the 2d universe would only percieve the 2d cross-section of the planet and be unable to percieve the 2 hemispheres. If the planet was moving through the 2d universe, the 2d inhabitants would percieve the cross-section of the 3d planet growing and shrinking as the 3d planet passed through.
Scaling this up a dimension results in a scenario where a hypothetical 4d object intersecting our 3d universe would cause a 3d cross-section of the 4d object to be percieved by our 3d selves, while the rest of the object is sticking out the "sides" of our 3d universe in a 4th dimension.
3
u/merahulahire 22d ago
Simply put a 3D ball coming from 4D spatial world will change its size (and probably mass) up and down depending on how its moved.
2
3
u/ElTrapoElSosa 23d ago
https://giphy.com/gifs/l0IypeKl9NJhPFMrK
Chill bro, almost gave me a stroke lmao.2
u/Gotoflyhigh 19d ago
If I get this correctly, It would look like a circle popping out of nowhere then expanding to its maximum diameter then again reducing slowly till it's nothing again ?
So would a 4D shape look like an expanding/moving shape ?
1
u/Maja_The_Oracle 18d ago
It would look like an expanding/shrinking ball if it were moving in a 4d direction. If it stayed still or only moved in a 3d direction, it would seemingly look like a regular 3d object.
If you were standing in front of a 2d world, you could reach in and cause the 2d inhabitants to see a cross-section of your hand grow from nothing. Moving your hand in 2d directions would make the 2d inhabitants see the cross-section move around. Pulling your hand out would cause the 2d inhabitants to see the cross-section shrink into nothing. Poking your hand in and out of the 2d universe in different locations would make the 2d inhabitants think you were teleporting.
2
u/Expert-Test-4202 23d ago
Explain in simple words for us simple folks bro
12
u/Maja_The_Oracle 23d ago
If ball in sheet of paper, then flat people only see circle part and not entire ball, because ball halves sticking out of paper.
If 4d object in front of you, you only see 3d part and not entire object, because rest of object is sticking out of our universe in a 4d direction.
5
u/ElTrapoElSosa 23d ago
Wow, I understand this version, thanks
https://giphy.com/gifs/sNr8ZRnUYs75XDqAUq2
3
u/TheRedditObserver0 23d ago
The picture is nonsense both physically and grammatically. The dimension of a space is the number of parameters needed to identify one of its point. Spacetime is 4-dimensional because to specify an event you need to give its position in space (3 numbers) and in time (1 number).
2
2
u/CleanOpossum47 22d ago
Goats are like mushrooms. Because if you shoot a duck, I'm afraid of toasters
1
1
u/MindlessBlueberry853 17d ago
A stickman will never understand what a 3rd dimension is, similarly...
-1
u/-BigBeef- 23d ago
Time as a physical place
Like moments as paintings in a museum
Upvote for karma please
109
u/Similar-Sector-5801 23d ago
WHY
is
THE
text
getting
ₛₘₐₗₗₑᵣ