Do you believe in a 4th dimension?

[ZenMasterFlex]

I don't mean time as the 4th. I am talking about a fourth spacial dimension. Is it possible?

[TomBrooks]

I think some mathematicians and subatomic physicists are currently exploring upwards of ten dimensions.

[Lestat]

I won't say I believe in it as there isn't enough evidence yet. But I do think it's likely and that there may be many more than just 4 dimensions. I think string theory predicts 11 or 12.

I do think this is the most likely explanation for the current problems with gravity and, the origin of the universe.

[Andrew Karpinski]

I think it's genreally accepted that there are > 4 dimensions, atleast most of the books I've read on cosmology mention them pretty casually.

[tomdemaine]

I'm not sure I entirely believe in a 3rd dimension. That Z axis looks shifty to me.

[Lestat]

[ QUOTE ]
I think it's genreally accepted that there are > 4 dimensions, atleast most of the books I've read on cosmology mention them pretty casually.

[/ QUOTE ]

Really? I didn't know that. I thought string theory itself wasn't really commonly accepted yet. I hope you're right though. It's truly a marvelous concept.

[bunny]

I dont believe there are more than three spatial dimensions but I accept it is possible.

[Lestat]

Not trying to be funny, but serious question...

Why is it you are willing to believe in a supreme being you cannot see, feel, touch, hear, or smell, yet cannot accept a spacial dimension you can't see?

And I'm asking the same of myself here too. I am much more willing to accept there might be dimensions I cannot perceive, than invisible gods. I wonder why that is?

[jgorham]

While no experiments have (as of this time) actually observed a 4th spacial dimension, there exists a lot of indirect evidence that makes me believe it is more likely than not that 10 spatial dimensions exist. If this is something that is interesting to you, I recommend you check out either of Brian Greene's books, The Elegant Universe or The Fabric of the Cosmos.

Just because we can't see extra dimensions doesn't mean we can't observe their effects. Experimenters are currently devising ways to test for extra dimensions by observing their theoretical effect on gravity.

Based on the underlying equations of M-Theory (extension of string theory), the graviton, or particle which transmits the force of gravity, is not bound to the three common spatial dimensions the same way the particles for the other forces are (electromagnetism, strong and weak nuclear forces). As such the force of gravity would spread amongst all the spatial dimensions, which we only have not observed at this point due to the extra dimensions being really small (if they were large, we would have noticed them already).

To understand this principle, consider an incredibly massive object (the sun) which exerts a gravitational force. If there were only one spatial dimension, its gravitational force it exerts on you would be constant no matter where you stood in relation to the sun. This is true because the gravitons don't have the chance to spread out and weaken (think of light weakening as it travels from a source).

In two dimensions, if you increased your distance from the sun by a factor of 2, its gravitational force it exerts on you would be cut in half. As you add a third dimension, if you increase your distance by a factor of 2, the gravitational force you would feel is decreased by 4(2^2). Note that Newton observed this and described it as the inverse square law of gravity.

This process continues with each added spatial dimension, so if there are 10 spatial dimensions the force of gravity weakens by an exponential factor of 9. So if you were to increase your distance from the sun by 2, the force of gravity you feel would actually be decreased by 2^9, or 512.

Intuitively, this does make a bit of sense, considering how weak gravity is compared to the other forces - a tiny magnet can lift a paperclip off the ground as its electromagnetic force overcomes the gravity of the entire planet earth.

Why then did Newton describe the force of gravity (to stunning accuracy) as something which weakens by an exponential factor of 2 (rather than 9) as you increase distance? If there are extra dimensions, the explanation lies in the fact that they are so small that they very quickly become "saturated" with gravitons, at which point gravitons only have our 3 familiar dimensions to spread out in. So over large enough scales - anything we have ever directly observed - gravity would only be acting on our 3 familiar dimensions.

While it hasn't been accomplished yet, this theory is testible. Simply put, equations describing gravity in 3 dimensions predict different answers than equations describing gravity in 10 dimensions. So the key to test for the presence of other dimensions would be to observe the force of gravity over incredibly small distances.

The next generation of atom smashers are designed to test for and view any extra dimensions if they are at least as large as 1/1000 of a millimeter. The test involves smashing particles into each other, and using the law of conservation of energy, measuring to see if energy was truly conserved. If gravitons "escape" into the extra dimensions, then some of the energy from the collision will appear to have gone missing, effectively proving the presence of extra dimensions.

[Andrew Karpinski]

Lestat : My groundings in cosmology are tenuous at best, but the books I've read didn't deal with string theory, aside from describing it briefly. They mostly dealt with relativity.

[FortunaMaximus]

How about this?

You're asking for a fourth spatial dimension, or a perceptual dimension.

M-therory (matrix theory) maps out a 11-dimensional universe, of which are known: the three spatial dimensions, and the fourth being time. Time relates differently to space than the spatial dimensions do.

Practice of this theory allows you to extrapolate the definition and perception of those dimensions, throwing open the capability for more powerful and dense dimensions, interweaving within the fabric of the universe.

Posit: Time can relate to spatial perception, and takes on spatial qualities (It'll take 4 minutes to travel a kilometre, etc.) The other dimensions have the capability for spatial qualities, and don't exclude spatiality.

So, to answer your question: It depends.

There are other theories, of course. I happen to like this one.

[carlo]

We live in 3 dimensions but the next dimension is not the 4th but the 2nd. In this 2nd dimension lays the picture pattern of your image thought, more like a gestalt. Then there is the 1st dimension which displays no space and is related to time.

So our geometry lays it out(abstracted of course) into solid, line, and point. Beyond the point lays that which is eternal which doesn't lend itself easily to our earth bound thinking.

carlo

[sweetjazz]

[ QUOTE ]
I don't mean time as the 4th. I am talking about a fourth spacial dimension. Is it possible?

[/ QUOTE ]

Yes, but only in R^n for n > 3!

[Go Blue]

One word: "Flatland" (the book).

[Metric]

This is the sort of question that leads to verbal wars among serious physicists. There are several camps ranging from complete skepticism -- comparing belief in extra dimensions to religious belief -- to guarded open-mindedness, to those who are absolutely convinced.

Personally, I tend to think that spacetime is an emergent concept based on the large-scale limiting behavior of something else (infinitely differentiable spacetime manifolds don't seem very "fundamental" to me). If one adopts this point of view, "extra dimensions" may simply be a feature of how you choose to describe the theory mathematically -- for example, there is something called the AdS-CFT correspondence, which says roughly that you can explain a certain kind of 4-d black hole in terms of a certain 10-d theory.

However, this may be dodging the question a bit. Let's just say that my belief in extra dimensions would be much more concrete if there were any direct supporting experimental evidence at all.

[bunny]

[ QUOTE ]
Not trying to be funny, but serious question...

Why is it you are willing to believe in a supreme being you cannot see, feel, touch, hear, or smell, yet cannot accept a spacial dimension you can't see?

And I'm asking the same of myself here too. I am much more willing to accept there might be dimensions I cannot perceive, than invisible gods. I wonder why that is?

[/ QUOTE ]
I only came to a theistic view after a personal (non-physical) experience - in fact a number of repeating experiences for which God existing was the best explanation I could find. I would adopt a belief in a 4th physical dimension if I experienced it in some way (though I find that hard to imagine) - I would also believe in it if there was experimental data which indicated it was likely to be true. If I may speculate - I expect you are more willing to accept the extra dimension than you are to accept a god due to the method the different advocates have used to reach their beliefs. The theists argue for a god in a variety of ways, none of which seem like a good guide to truth to you. The physicists who argue for a real 4th dimension have reached that position through scientific theorising (even though it has not as yet been experimentally verified) and I think you have more confidence in this leading to truth.

With regard to why I dont accept the widespread use of extra dimensions as evidence that a fourth dimension exists - I think there are many ways to model physical problems, some of which seem very divorced from their real-world counterparts (as a poor example but the best I can think of at the moment - you can model planetary orbits as an sum of circular paths, epicycles I think they were called, the more you add the closer you get to the true position of planets. Or you can assume there is a universal gravitational force and lo and behold, planets move in ellipses). Until I see physical evidence backing up these theories (or hear about it anyway) I am hesitant to say "Here's a model that fits what we've seen, so it must be true in the areas we havent seen".

Obviously I think it is a very real possibility that these extra dimensions actually exist - I just havent seen any evidence for them yet.

[Lestat]

Although you've mentioned them several times, we never did get into exactly what non-physical experiences led to your current theistic views. Whatever they were, I suspect it must've been pretty powerful. I also wonder if it could've been another dimension you were experiencing? -lol Mostly kidding...

[bunny]

When I doubt my belief in God it is, of course, along exactly these lines. I know physical things can influence my mind so how do I know it isnt some physical process deluding me into believing in God?

I would also point out that unlike most in the pro-God camp here I adopt the view that my theism is rational but my Christianity is irrational. When I argue for God's existence (or more usually defend it as a logical possibility) I am not arguing for the christian god but the theist one (and even that is beginning to morph in my mind into something else).

[LadyWrestler]

Yes!

[11t]

I would say the concept of God is a far easier thing to think about than a hypercube (cube in the 4th dimension). Objects in the 4th dimension are basically impossible to visualize or represent in a 2-d or 3-d presentation and can only really be "looked at" mathematically.

Therefore since most people do not have that mathematical knowledge capability I would say it is not surprising that more people believe in God (not proven) than a 4th dimension (proven).

It is like an ant tryiing to think of "up". It only knows forward, back, left, right. Probably a poor analogy but I think you get the point.

[yukoncpa]

[ QUOTE ]
I would say the concept of God is a far easier thing to think about than a hypercube (cube in the 4th dimension). Objects in the 4th dimension are basically impossible to visualize or represent in a 2-d or 3-d presentation and can only really be "looked at" mathematically.


[/ QUOTE ]

Hi,
A while back, I read a very interesting book called Hyperspace, by Kaku. He talked about multiple dimensions, and pointed out artists such as Dali and Picasso, who through their art, tried to visualize a 4th spatial dimension. The whole book was really quite interesting. Another book that does a good job helping you to "visualize" a 4th dimension is, Flatland.

[fanmail]

It is highly possible there are 4 or many more dimensions. However, belief is not required.