# How probable is a 4th spatial dimension?

Asked by HolographicUniverse (1668) August 5th, 2012

Instead of time?

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## 20 Answers

I’m not sure what you mean by “instead” of time. It’s possible that there are four spacial dimensions as well as the temporal dimension.

Couldn’t assign a value to the probability, but the idea isn’t so “out there.” Some string theory models hypothesize an 11 dimensional universe.

One interesting tidbit to think about… the nonstick coating on certain pans is composed of a crystal whose structure doesn’t make sense in a universe with 3 spacial dimensions.

Check out Lisa Randall’s Warped Passages if you’re interested in this subject.

Mariah (23088)

I think the question is based on the fact that time is often referred to as the fourth dimension.

So essentially asking what if time is just a fourth dimension. And there are other options.

I think until we have the tools to prove anything operates in more or less than three dimensions it’s all theoretical work. It’s still valuable, but someone is going to look like a prescient genius, and a lot of people will look like those who believed the Earth was the center of the universe.

funkdaddy (14714)

Some models of the universe require something like nine or twelve dimensions. But the fact that there are so many dimensions doesn’t mean there are any more than three spatial dimensions. The other dimensions may describe other kinds of attributes of the universe.

wundayatta (58484)

I’m unsure how to reply directly to answers, but @Mariah.

The problem with your proposition, and many string theory models that postulate 11* dimensions, is that they’re merely theoretical and hardly probable. Many aren’t based on maths, Sagan and Kaku’s ideas were the most explanatory on a basic level yet still mere speculation. And as Wundyatta sad, depending upon the model, there can be many dimensions but they are not spatial, they contributive such as time (and just as many feel it’s matter)

Suffice it to say I believe it’s highly unlikely. And “instead of time” was a mistake in wording.

My Agnosticism is not limited to merely religious things. However, I am a firm believer of the old adage, “Not only is the Universe stranger than we imagine, it’s stranger than we can imagine.”. Therefore, I would not rule it out as we have no way of really disproving it at present.

jerv (31025)

Anything is possible.

zensky (13357)

I think that trying to find out how the universe works is pretty much pointless. Because there is the Answer and the Question. First we find the Answer, the “Theory of Everything.” The we must find the question. Now Hitchhikers here “If the question and the answer are known to the same person the universe will imediatly dissapear and be replaced by something even more bizzare and unexplainable. There is another theory that states that this has already happened.” I believe the former. I don’t fell like dissapearing anytime soon so can we please stop looking to explain the universe?

Mr_Paradox (3017)

If you want my opinion, as opposed to what I know about what the physicists say, I don’t think it is at all likely that we will ever discover a fourth spatial dimension. The reason is that we aren’t equipped to perceive it. If it were important, we’d probably have evolved a way to perceive it.

If we “find” another spatial dimension, it won’t be spatial to us, because we can’t perceive it. So it will be theoretical or only detectible with special instruments, and it won’t matter to us on anything other than a theoretical level. If we can’t perceive it, then it’s existence is highly problematic. What does the existence of the higgs boson mean? It is only by building the most expensive and large particle detector ever that we can detect it. And no one can perceive it directly. It doesn’t matter.

Let’s suppose the boson is a 4th spatial dimension. What is its significance? None, in terms of every day existence. It might be huge in terms of understanding how the universe works, and it might have huge technological implications, but in terms of life as we experience it, it is nothing. Any 4th spatial dimension will be the same.

wundayatta (58484)

@Mr_Paradox

But could this universe be on an infinite loop? Or are we a one shot deal until we learn more, to understand the universe is to understand our potential to strive and excel as a species no?

@wundayatta
You may be on to something my friend, I think your conclusion is very very comendable and I agree that we cannot perceive. I don’t agree that should we discover the 4th spatial dimension (speaking hypothetically) that it means nothing for the experience of life, can you imagine the possibilities with such technology? Ad the experience of life in a 4th dimension?

@HolographicUniverse Technology—sure. Experience? No way. We don’t have the perceptual equipment. At best, it would be a virtual experience. We’d use detectors, and then display the results on the displays we are used to—false color, fake three dimensional views. No different from everything else.

We would need to develop a new sense to be able to perceive the new dimension. Evolution doesn’t happen that fast. Perhaps we could genetically engineer ourselves a new sense, but we could do that for anything. If we wanted to develop a human boson detector, or an xray detector, and if we had the genetic technology to do so, we would experience the new sense pretty much the same way, no matter what it was detecting. Not sure what that would be like.

Perhaps it would depend, to some degree, on what was being detected, and the character of that thing, but mostly, I think it would mess up our brains and interact with our other perceptions in much the same way.

wundayatta (58484)

In our everyday experience there are only 3 spatial dimensions. If there were extra dimensions then it would be possible for someone to move out of sight while seeming to remain in the same place, like the Cheshire cat, by traveling along some extra dimension. Since that does not happen, we can conclude that 3 dimensions are adequate. The classic novel Flatland gives a good description of what it would be like for the residents of a 2 dimensional world to be visited by someone from our 3 dimensional world.

In String Theory, the extra dimensions are all curled up and have microscopic breadth.

LostInParadise (22136)

@HolographicUniverse Sure, it’s just something I enjoy thinking about. As yet it’s completely unrealistic to try and draw a conclusion either way.

Here’s another something fun to think about. As @LostInParadise mentioned, extrapolating from 2, to 3, to 4 dimensions (as in Flatland) is the best way to think about a fourth dimension. The only way, really, since it seems to be impossible to actually picture four-dimensional objects in our heads.

So picture this. A creature painted on the surface of Earth believes he is 2 dimensional. In reality, he is 3 dimensional, but only very slightly so, because of the curvature of the earth. One day he goes for a walk. He walks and walks in a “straight” line, and eventually he circles the Earth and ends up back where he started. And he’s utterly confused because as far as he knows he should be miles and miles from where he started. It’s conceivable that our reality could be very subtly four dimensional so that we don’t notice it (in this way I disagree with @LostInParadise‘s assertion that we can assume there are only 3 spatial dimensions), and a rocket sent far enough might end up back where it started. Again, not saying this is true, or even that there’s evidence for it; it’s just fun to think about.

Mariah (23088)

@Mariah , It is still not known whether the Universe is finite or infinite. If is is finite, it would be topologically equivalent to the 3 dimensional surface of a 4 dimensional solid. This would not, however, mean that there really is a four dimensional solid. See, for example, The Shape of Space

LostInParadise (22136)

@LostInParadise Interesting, thanks. I don’t understand this nearly as well as I would like, so continue to correct me if I say anything wrong. One thing I don’t understand – how is the surface of a 4 dimensional solid, 3 dimensional? The surface of a sphere, for instance, is just a hollow sphere, not a 2 dimensional circle.

The universe is so very strange. I love that about it.

Mariah (23088)

@Mariah , I can use your own example of the creatures painted on the surface of the sphere. The surface is 2 dimensional. In this case, there really is a 3 dimensional object supporting the 2 dimensional surface, though this need not be the case. For example, imagine playing a computer game that wraps around top and bottom and also left and right. Topologically, that is equivalent to a 2 dimensional surface of a 3 dimensional object. In this case, the shape would be equivalent to the surface of a donut, or a torus, to be mathematical about it. In the same way, our universe could be equivalent to the surface of a 4 dimensional object.

LostInParadise (22136)

@LostInParadise, thanks, that’s starting to make sense…one last question, sorry if this is derailing the thread. OP, if you want me to stop, just say the word. I still see the creature painted on the surface of the sphere as being 3D. If you take away the sphere and just look at the creature and its shape, wouldn’t it have a length, width, and height? Like a piece of paper bent into an arc: the paper itself isn’t thick, but the arc shape creates dimension.

Mariah (23088)

Consider the creature painted on a flat piece of paper. Now fold the paper into a cylinder. The creature will have no perception of what you just did. The cylinder is of course topologically different from the flat paper, because it wraps around. Locally, from the creature’s point of view, there is no way of distinguishing the two cases. Folding the paper causes no stretching or shrinking of any part of the surface (assuming that it really is 2 dimensional). There is no experiment that the creature could perform in its world that would demonstrate the curvature. It is only when it walks around the cylinder and comes back to its original position that the creature will understand the curved nature of its world.

The case of the sphere is more complicated, because a flat surface would have to be stretched in some places and shrunken in others to form a sphere. At this point, I run into the limits of my mathematical knowledge.

LostInParadise (22136)

@LostInParadise, thank you for all the great explanations!

Mariah (23088)

I’m not an expert on this either, and which I could explain it with the clarity of @LostInParadise, but one thing that helped me understand and that I try to extrapolate along further is the thought that each dimension seems to take into account the possibilities of the last…

If we think of a point as having zero dimensions then a line is all possibilities for that point in a one dimensional space.

If we take a line and extend it to two dimensions then a plane would be all possibilities of that line represented at once.

If we take that plane and extend to three dimensions, then a cube would represent all the possible planes at once. (assuming we put some limits on our “universe” at some point so it doesn’t just extend forever)

So when I try to extend that example to a fourth dimension the easiest way to think of it is all the possible cubes represented at once.

This is what mathematicians say it would look like when rotating, my mind sees it more like this with the curves representing some sort of relative “density” of the new solid. I’d go with the mathematicians since this stuff is right at the limit of what I can do spatially. ;)

Some more on the sculpture, which is pretty interesting.

funkdaddy (14714)

@Mariah
@LostInParadise
@Wundayatta

I will be addressing you all momentarily but while skimming over the answers, I came across the flatland interpretation and felt it was highly unnecessary to quote it again as it seems that one is implying that a 4th spatial dimension would be as perceivable to a 3 dimensional space as would the 3rd dimension to 2nd.

Think of the tesseract, not a sphere, the 4th space would have to consist of an extra “layer” of definition, if we are to speak this topic then we can only rely on mathematical postulations and spatial imagery.
The idea that we will/can never know has already been recognized

My perception of a 4th spatial dimension is, if anything, the display of microscopic entities but of course that’s purely assumption. I will speak to you soon.

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