- #1

revesz

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He also said that for string theory to work that there must be 6 additional dimentions, so what are the other 5 dimentions?

11 dimentions....WHAT?

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- Thread starter revesz
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- #1

revesz

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He also said that for string theory to work that there must be 6 additional dimentions, so what are the other 5 dimentions?

11 dimentions....WHAT?

- #2

Ambitwistor

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In the TV show, Elegent Universe, Brian Greene explains that there are 11 dimentions of space and time, but why exactly 11?

The theory is only consistent in 11 dimensions, as far as people know. If you try to do string theory in other dimensions, you end up running into problems upon quantization: probabilities aren't conserved, or symmetries are broken, etc.

He also said that for string theory to work that there must be 6 additional dimentions, so what are the other 5 dimentions?

Seven extra dimensions, in 11-dimensional M-theory: 1 time dimension, the usual 3 space dimensions, and 7 more space dimensions (usually taken to be curled up small to explain why we don't see them).

- #3

lethe

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Originally posted by Ambitwistor

The theory is only consistent in 11 dimensions, as far as people know. If you try to do string theory in other dimensions, you end up running into problems upon quantization: probabilities aren't conserved, or symmetries are broken, etc.

i must confess, i am wholly ignorant of M-theory. i know the derivation that shows that the supersymmetric string lives in critical dimension 10, and i believe them when they tell me that this is the only possible choice.

so i have always wondered what kind of fast trick witten pulled by moving to 11 dimensions... that is certainly not the critical dimension allowed in conformal supersymmetric field theory, and required for unitary.

presumably, there is some construction in M-theory that produces a unitary model in 11D, but i guarantee you, it aint supersymmetric field theory on the world sheet. so what is it?

- #4

revesz

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So how do the other 6 or 7 dimentions work?

Why are they needed?

Why are they needed?

- #5

Netme

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The seven extra dimensions are not seperate physical dimensions at all. We exist within these seven extra dimensions just as we do ours but can only view our dimension normally because of the way we function. These dimensions may be needed to allow for the formation of new more advanced processing forms but this would suggest that the dimensions are not set at seven but rather they will continue whenever a new form is created. Dimensions are what make evolution possible. When a new form of processing is created a new dimension must also be created to allow for the normal functioning of its kind. For example we would not be able to function within the dimension of an atom because our bodies and minds are a combination of atoms making us need to process at a quicker rate in order to keep up with atoms that make up our body. So these seperate dimensions are really just variations in processing which would explain why we cannot rapidly see the formation of our planet. In order to understand what changes our universe will go through or to see symmetry in our univers we would have to understand how processing ahead of ours has evanced and if we do this we could emulate and predict what fate lies for us as well.

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- #6

revesz

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- #7

suyver

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Kind regards,

Freek Suyver.

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selfAdjoint

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dlgoff

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There are some multitime theories around, ....

Greetings,

Can you give a link or two for this?

- #10

- #11

...

Ten eD ('entangled' Dimensions).

https://www.physicsforums.com/showthread.php?threadid=9701

... [?]

Ten eD ('entangled' Dimensions).

https://www.physicsforums.com/showthread.php?threadid=9701

... [?]

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- #12

MymMars

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- #13

DaveC426913

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MymMars said:I think any 3 dimentional object with a density of zero would not take up any space.

Density is merely a derived property, not an intrinisc property. It is nothing more than the mass divided by the volume. Volume is merely the extent of an object in the existing three dimensions. Mass, on the other hand, you could maybe make an argument about it as a dimension.

- #14

chingkui

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There are some multitime theories around, ....

What will it like if the universe has another extra time dimension???? Time, as I understand (or experience) it, can only has 1 dimension: there is past and there is future... so, how will an extra time dimension change the physics?

- #15

chingkui said:What will it like if the universe has another extra time dimension???? Time, as I understand (or experience) it, can only has 1 dimension: there is past and there is future... so, how will an extra time dimension change the physics?

Hi all.

Well I am going off on my own here, and what I have to say has nothing to do with any branch of known physics which I have encountered. However.

In space, we have length, and length times Length which is area, (LxL or LL or L^2 or [tex]L^2[/tex] and Length times Length times Length which is volume (LLL, L^3, [tex]L^3[/tex]and so on). We don't like to talk about LLLL, or any more L's than that. I am not sure why except that it is hard to think about and some famous people have said that it is impossible to think about. Oh well. For them maybe.

And then we do have multiples of time in everyday physics, only the multiples occur in the denominator, the inverse side of the ratio, under the division sign. For example, L/T (T for time) is velocity, and L/TT or [tex]L/T^2[/tex] is acceleration, and L/TTT is a quantity known in ballistics as jerk. Sorry about that but that is what it is called. I am not sure why physicists use these formulas routinely and still insist there is only one dimension of time, but there it is.

And then there is Einstein-Minkowski spacetime, in which our beloved uncle Albert and his math teacher agree that space and time are really the same thing. So we should have at least three dimensions of space and three dimensions of time, not?

But that is only six dimensions, if you accept my logic, which I have to warn you is not advisable. Please do not pester your physics teacher with this stuff, because I know for a fact that they will be very irritable about it.

Personally, I like the notion, which I have just now invented, that what we see around us and proclaim as real is actually the condensed spacetime dimensions described in Calabi-Yau maths. The other dimensions are the very large ones, open ended dimensions that, so far as we know, run out to infinity.

Anyway, there are some formulas in physics which involve numbers like [tex]c^5[/tex], which in my clumsey notation would be LLLLL/TTTTT. Ahem. That would seem to be five dimensions of space and five dimensions of time, or, as we can all add, ten dimensions. This is strictly unorthodox and again, has nothing to do with mainstream physics, and students of physics would do well to ignore it, as has been done for a couple hundred years now by everybody of any importance whatsoever. But I do assure you that c^5 really is a number used by ordinary physicists, altho I don't know of any who would say comfortably that it represents ten dimensions.

Now, then, I hope we are all satisfactorily tucked into wonderland, and that poor Micheal Jackson doesn't undergoe a horrific collapse in the courtroom. Too much imagination may not be a good thing after all. But as long as it keeps you studying physics and math, hey, why not? Only do take my advice on this, and keep your hands off of dimensions that do not belong to you.

nc

- #16

chingkui

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There are some multitime theories around, ....

I mean, what make a dimension a time dimension rather than a space dimension? Is it the sign different in the Lorentz Invariant?

With extra time dimension, the topology of the time dimensions will be very different, what is the physics like with extra time dimension? Had someone ever writen a consistent electrodynamics with an extra time dimension? What would the Maxwell Eq be like in that case?

- #17

Chronos

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- #18

codyg1985

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What I am getting to is that if there is a second (or even third or higher time dimensions), then it would be "perpendicular" to the first time dimension we are familiar with. Maybe it means nothing, or maybe it means the divergence to different possible futures.

I am not a physics expert by any means, so some of this stuff may turn out to be impossible.

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selfAdjoint

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codyg1985 said:What I am getting to is that if there is a second (or even third or higher time dimensions), then it would be "perpendicular" to the first time dimension we are familiar with. Maybe it means nothing, or maybe it means the divergence to different possible futures.

The two or more orthogonal time dimensions would span a "time vector space" so rather than just t1 and t2, you would have a*t1 + b*t2 as your time thingy, with a and b any two constants. Or of course higher dimensional equivalents if there were more time dimensions. So it's not divegence of two or three futures but a complex mix of infinitely many possible "paths through futurespace". Nice idea (and title!) for a science fiction story.

- #20

spicerack

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Now it seems he is getting support from factions of the physics community and your paths through futurespace is not unlike him choosing to navigate different timelines of a possible future

http://www.johntitor.com/

- #21

MymMars

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In thinking about another time dimension; I see that time doesn't behave the same as the spatial dimensions in that the first 3 shows what space as occupied. Time shows what space isoccupied at a given interval. I think is quite possible to have other dimensions that have similar properties to time. I am thinking about Frequency as a time like dimension. Time can show matter in the same space at different times. Frequency could show matter in the same space at multiple frequencies, both higher and lower than the visual range.

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- #22

SelfAdjoint, I still wonder about why time squared in the denominator of acceleration isn't taken to be clear evidence of another time dimension. We need two space dimensions to accomodate surfaces. Why then do we fail to extend this to time?

Be well,

Richard

- #23

selfAdjoint

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nightcleaner said:

SelfAdjoint, I still wonder about why time squared in the denominator of acceleration isn't taken to be clear evidence of another time dimension. We need two space dimensions to accomodate surfaces. Why then do we fail to extend this to time?

Be well,

Richard

But when we do the corresponding thing with length that we do with time in acceleration (writing "time unit per time unit" as "1/time^2"), we don't go to two space dimensions. Namely when doing the curvature of a curve, which is a second derivative with respect to length, or length unit per length unit, we write 1/length^2 and it has nothing to do with surfaces. To make this a little clearer, imagine you are moving along a curve and calculating the radius of curvature as you go. Then you ask "How fast is the ROC changing?" and the answer is so many inches of change

You might say, "But it takes more than one dimension for the curve to curve!" However this is that old intrinisic situation. The math of the curvature doesn't require the extra dimensions for the curve, any more than it does for general relativity curvature of spacetime geometry.

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- #24

selfAdjoint said:But when we do the corresponding thing with length that we do with time in acceleration (writing "time unit per time unit" as "1/time^2"), we don't go to two space dimensions. Namely when doing the curvature of a curve, which is a second derivative with respect to length, or length unit per length unit, we write 1/length^2 and it has nothing to do with surfaces. To make this a little clearer, imagine you are moving along a curve and calculating the radius of curvature as you go. Then you ask "How fast is the ROC changing?" and the answer is so many inches of changeper inch of travel. Slopes of mountains and such are expressed the same way.

You might say, "But it takes more than one dimension for the curve to curve!" However this is that old intrinisic situation. The math of the curvature doesn't require the extra dimensions for the curve, any more than it does for general relativity curvature of spacetime geometry.

Yes, the math can be done in lower dimensions than the objective reality (physics) being described....just as a three dimensional object can be drawn completely in two dimensional views....still, the object called "circle" or "curve" is and has to be at least two dimensional, does it not?

- #25

selfAdjoint

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nightcleaner said:Yes, the math can be done in lower dimensions than the objective reality (physics) being described....just as a three dimensional object can be drawn completely in two dimensional views....still, the object called "circle" or "curve" is and has to be at least two dimensional, does it not?

No, a circle is one-dimensional. Imagine a microscopic being living on one. It would think it lived on a line, unless it was the Magellan of its race and circumnavigated its world.

It is very hard to break the confusion between the nature of a manifold and the nature of its embedding in a higher space; all our examples of lower dimensional manifolds (curves and surfaces) are embedded in our three dimensional space. But their topological and metric properties do NOT depend on th nature of that embedding.

- #26

selfAdjoint, I have huge respect for your knowlege and skills in maths and physics. I know in advance of this sally that you are giving the correct version of things as they are. If I argue over this ground, it is because I want to be able to see for myself exactly where my vision fails and the vision you present succeeds. Thanks for being willing to wrestle.

You say "It is very hard to break the confusion between the nature of a manifold and the nature of its embedding in a higher space."

It seems to me that this confusion arises from a vagueness, or freedom, in the position of the observer. Is the point of view of the observer taken on the curve or off the curve? To an observer on the curve, it appears to be a straight line. No method entirely on the curve can give evidence that the curve is other than one dimensional. An observor entirely on the curve is curved and so are all the tools of measurement available, so long as they are strictly on the curve.

Only when the point of view of the observer is allowed to stray off the curve is it apparent that the curve exists as other than a straight line. I am put in mind of Einstein's popular work on special relitivity, in which IIRC he shows how a ball dropped from a moving train follows a straight line path to the ground from the point of view of a passenger, but follows a curve from the point of view of the man on the platform at the station.

One might devise an experiment where the man on the train drops the ball along a straight edge affixed to the train. Clearly the ball will follow the line of the straight edge. Even the stationary man will see the straight edge as straight, and will see the ball follow it.

But if the experiment is arranged so carefully that the ball is dropped precisely as it passes a fixed point on the platform, the stationary man might be able to predict the fall of the ball, from the laws of gravity and so on, and cut for himself a piece of plywood with a curved edge, along which the path of the ball will follow.

Both the train man and the station man will see the straight edge fixed to the train and the curved edge fixed to the platform, and both will see the ball follow smoothly along both the curved edge and the straight edge, simultaneously. We can in fact eliminate the ball entirely and just look at the intersection of the straight edge with the curve as the train passes. Yikes! or maybe, Yoikes. We see that a curve or a straight line can equally well describe the motion of the ball, which all agree is a unique event.

Now maybe we must forget about the notions of straight line and curve entirely and focus instead on.....what? Uh oh. I am not coming up with anything.

any help?

be well,

R

You say "It is very hard to break the confusion between the nature of a manifold and the nature of its embedding in a higher space."

It seems to me that this confusion arises from a vagueness, or freedom, in the position of the observer. Is the point of view of the observer taken on the curve or off the curve? To an observer on the curve, it appears to be a straight line. No method entirely on the curve can give evidence that the curve is other than one dimensional. An observor entirely on the curve is curved and so are all the tools of measurement available, so long as they are strictly on the curve.

Only when the point of view of the observer is allowed to stray off the curve is it apparent that the curve exists as other than a straight line. I am put in mind of Einstein's popular work on special relitivity, in which IIRC he shows how a ball dropped from a moving train follows a straight line path to the ground from the point of view of a passenger, but follows a curve from the point of view of the man on the platform at the station.

One might devise an experiment where the man on the train drops the ball along a straight edge affixed to the train. Clearly the ball will follow the line of the straight edge. Even the stationary man will see the straight edge as straight, and will see the ball follow it.

But if the experiment is arranged so carefully that the ball is dropped precisely as it passes a fixed point on the platform, the stationary man might be able to predict the fall of the ball, from the laws of gravity and so on, and cut for himself a piece of plywood with a curved edge, along which the path of the ball will follow.

Both the train man and the station man will see the straight edge fixed to the train and the curved edge fixed to the platform, and both will see the ball follow smoothly along both the curved edge and the straight edge, simultaneously. We can in fact eliminate the ball entirely and just look at the intersection of the straight edge with the curve as the train passes. Yikes! or maybe, Yoikes. We see that a curve or a straight line can equally well describe the motion of the ball, which all agree is a unique event.

Now maybe we must forget about the notions of straight line and curve entirely and focus instead on.....what? Uh oh. I am not coming up with anything.

any help?

be well,

R

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- #27

Catchism

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I had a similar inquiry when a friend of mine recommended I watch the Bryanton video on the 10 dimensions: A very succinct interpretation of dimensions beyond the 4th. But where is the 11th?

http://www.tenthdimension.com/medialinks.php.

JkxieS-6WuA[/youtube][MEDIA=youtube...as impossible until the advent of the zero...

http://www.tenthdimension.com/medialinks.php.

JkxieS-6WuA[/youtube][MEDIA=youtube...as impossible until the advent of the zero...

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