Extra Dimensions in String Theory

[Icarus]

Hello,

I understand that String Theory requires 10-11 dimensions, depending on the specific author of the theory. M-theory requires 11. My question is, why do we need the extra dimensions? All I've read is that they are needed to make the equations work, but no one goes into what they mean by that.

I think it is because we need extra "space" for the strings to travel through when they are not affecting our dimensions. So they could be in these spherical or curled up dimensions that co-exist within or outside our 4-dimensional space.

Can anyone elaborate on this at all? I'm confused but highly interested by string theory.

Thanks,

-Icarus

[dingo]

From http://en.wikipedia.org/wiki/String_theory#Extra_dimensions :

... string theory allows one to compute the number of spacetime dimensions from first principles. Technically, this happens because Lorentz invariance can only be satisfied in a certain number of dimensions. This is roughly like saying that if an observer measures the distance between two points, then rotates by some angle and measures again, the observed distance only stays the same if the universe has a particular number of dimensions.

I don't understand it that well.. maybe someone else could elaborate further.

[Icarus]

Thanks Dingo,

No one else can elaborate? It seems like their just saying they exist because we need them to exist... which is bleh.

Anyone?

-Icarus

[dingo]

I think it's because in four dimensions there are only so many ways strings can vibrate but if you add the other 7 you find that the vibration of the string can describe every kind of matter.
That's the impression I got from some TV show on a long time ago... Although I could be totally wrong.

[MisterJingo]

Hello,

I understand that String Theory requires 10-11 dimensions, depending on the specific author of the theory. M-theory requires 11. My question is, why do we need the extra dimensions? All I've read is that they are needed to make the equations work, but no one goes into what they mean by that.

I think it is because we need extra "space" for the strings to travel through when they are not affecting our dimensions. So they could be in these spherical or curled up dimensions that co-exist within or outside our 4-dimensional space.

Can anyone elaborate on this at all? I'm confused but highly interested by string theory.

Thanks,

-Icarus

Hi Icarus,

you might find the following site interesting:

http://www.slimy.com/~steuard/research/MITClub2004/index.html#outline

It's a presentation given by a string theorist aimed at a beginner level (it might be a bit heavy going in parts but googling can fill the gaps).
Rather than regurgetate the 'why' for extra dimensions, it should be explained in the above.

[Icarus]

Thanks for the link MisterJingo. I'm reading through the slides now, I hope it starts to clear things up a little. Man, and I thought I had a good grasp on this theory after seeing The Elegant Universe! Well, we'll see.

Thanks again,

-Icarus

[RooJ]

I downloaded and watched the elegant universe yesterday, it seems dingo is right, in order for strings to describe every type of matter they would need extra dimensions. Of course that only means that 11 dimensions where predicted so the math would work .

[maddutchman]

As far as I understand the principle behind the extra dimensions(as stated in 'what the bleep do we know?'), is partly due to the belief that all energy within an atom (string particle) isn't static.
They've found reason to believe that energy pops in and out of existence(in these 4 dimensions anyway), quarks, neutrinos, electrons, nuclei, travel across dimensions only to come into existence in this dimension as soon as we the 'observer' relate to it on some level through one of our senses.
As to why the belief of 12 dimensions, I'm not to sure.
12 SOUNDS A LITTLE LIMITING TO ME!
I was watching a doco by NOVA about the whole string theory phenomena.
They related the extra dimensions as if an ant were walking along a stretched piece of string. the ant moving forward from one spot brings it into the second dimension. if it were to rotate around the wire as it was moving it would be in the third dimension.
Imagine if the ant were to stumble across a loop the loop along its forward travels;apparently theres another three dimensions there, and if it hit another loop the loop on the first loop the loop its just run into another three dimensions.

now the first three dimensions, plus time makes four dimensions. four dimensions X3 ( straight tube ,plus two loops) will give you twelve.
That was there explanation of it .
I understand it, but I don't see why this couldn't be an infinite paradox.
you could take it to the Nth degree.

[dingo]

(as stated in 'what the bleep do we know?')

You might as well quote from snow white and the seven dwarfs, it's just as factually accurate.

[CFTraveler]

dingo wrote:

You might as well quote from snow white and the seven dwarfs, it's just as factually accurate.

This is a good example of throwing away the baby with the bathwater.  Not all the quantum physicists were misquoted, and not everything was channeled information.
There were some physicists that were quoted accurately, and at least one neurologist that agreed with their conclusions.

[maddutchman]

(as stated in 'what the bleep do we know?')

You might as well quote from snow white and the seven dwarfs, it's just as factually accurate.

Tell me anything within quantum mechanics that is factually accurate. If were going by the notion of quantum mechanics being the science of possibilities, everything is gray, nothing is black and white.
Quantum mechanics opens up to the notion that everything and nothing is possible at the same time. It is just throwing around abstract notions until someone hits upon something that works better in theory than an existing ideal.
Matter of fact that is just science and maybe life in general.

[dingo]

dingo wrote:

You might as well quote from snow white and the seven dwarfs, it's just as factually accurate.

This is a good example of throwing away the baby with the bathwater.  Not all the quantum physicists were misquoted, and not everything was channeled information.
There were some physicists that were quoted accurately, and at least one neurologist that agreed with their conclusions.

It was about quantum mechanics, not neurology (and thats ONE neurologist out of thousands around the world?). The physicists that were quoted accurately were still used to 'support' the film. People would naturally assume that since one part of what was said was accurate, the whole film was accurate.
I'm "throwing away the baby with the bathwater" because the baby gives the impression that all the bathwater is accurate.

Tell me anything within quantum mechanics that is factually accurate. If were going by the notion of quantum mechanics being the science of possibilities, everything is gray, nothing is black and white.
Quantum mechanics opens up to the notion that everything and nothing is possible at the same time. It is just throwing around abstract notions until someone hits upon something that works better in theory than an existing ideal.
Matter of fact that is just science and maybe life in general.

Quantum theory is based on probability, yes, but that probability is governed by rock solid laws. The theory itself is very black and white, but the outcomes of a situation modelled in the theory aren't.
Seriously, don't rely on "What the bleep do we know" for information about quantum mechanics (or theory).

[maddutchman]

[/quote=Dingo]]
It was about quantum mechanics, not neurology (and thats ONE neurologist out of thousands around the world?). The physicists that were quoted accurately were still used to 'support' the film. People would naturally assume that since one part of what was said was accurate, the whole film was accurate.
I'm "throwing away the baby with the bathwater" because the baby gives the impression that all the bathwater is accurate.[/quote]

The film wasn't just about quantum mechanics. It was about quantum mechanics in relation to our perception and the way we live our lives.
Our lives = everything.Quantum mechanics doesn't exist in a vacuum.

Dingo , probability isn't governed by rock solid laws. If that were the case the would be definites, not probables.
The laws themselves are just the best information we can succinctly piece together at the time, from a whole heap of other 'most probables(not definites).
This forum should be proof enough, that what society has often thought of as 'rock solid'.......... isn't.
As time goes by physicists have amended and added to these laws to make certain laws closer to the 100% mark.It wasn't all that long ago that scientists thought atoms were solid.

I agree with the point that 'What the bleep do we know?' may have been misquoted. That's the media, It will MOST PROBABLY never change.
I don't think the baby gives the impression the bathwater is accurate.
I think the baby with its limited viewpoint, has offered something to get people to think about the nature of reality.
What is accuracy?What is deemed accurate to one person may not be to another. Place a magnifying glass over it and you are still  further from the mark than you were before.

[MisterJingo]

Tell me anything within quantum mechanics that is factually accurate. If were going by the notion of quantum mechanics being the science of possibilities, everything is gray, nothing is black and white.
Quantum mechanics opens up to the notion that everything and nothing is possible at the same time. It is just throwing around abstract notions until someone hits upon something that works better in theory than an existing ideal.
Matter of fact that is just science and maybe life in general.

Just because a lot of QM is based on probability doesn't make it not factually accurate. String theory is the one looking for empirical evidence, QM has evidence in the bucketful.
Most of modern technology is based upon QM, from LEDs, to transistors, to solid state electronics, to x-ray machines etc. Everything in your home which has a microchip was created solely through QM research.

If QM was not factually accurate, surely we wouldn't have been using technology built from it for the past 60+ years?

People assume that because QM uses probability, it is unknowable. If we look at a single particle yes, but when we look at a system then no. An easy analogy is that casinos (based on probability) always win. Probability taken over a large enough set becomes predictable as if mapped out it makes a very obvious bell curve.

Ps there is even empirical evidence for quantum foam (the creation and destruction of energy) in QM, and this evidence can be repeated and seen by anyone who has the means to do it.

[MisterJingo]

The film wasn't just about quantum mechanics. It was about quantum mechanics in relation to our perception and the way we live our lives.
Our lives = everything.Quantum mechanics doesn't exist in a vacuum.

Perception is one thing, but relating quantum theories to consciousness (when at best we've only related it to groups of atoms/particles) is taking such a huge leap as to become nonsensical. Many tenants used, such as the uncertainty principle (which seems to suggest an observer in reality) could be on its way out i.e. there are theories which suggest no observer is needed. People selectively choose theories to support their agenda irregardless if those theories are 100% accurate or not.

Dingo , probability isn't governed by rock solid laws. If that were the case the would be definites, not probables.
The laws themselves are just the best information we can succinctly piece together at the time, from a whole heap of other 'most probables(not definites).
This forum should be proof enough, that what society has often thought of as 'rock solid'.......... isn't.
As time goes by physicists have amended and added to these laws to make certain laws closer to the 100% mark.It wasn't all that long ago that scientists thought atoms were solid.

Probability is governed by rock solid laws. Else we wouldn't have been using it for centuries. The problem with QM is that we can use probability to get accurate result, we just don't have a defined 'why' it acts the way it does. That's why there are a lot of theories about such as the many world theory, waveform collapse, string theory, mtheory etc. One day we will have the knowledge to find which theory is correct, but until then we can still accurately use QM – as we do in everyone of our modern-day electronics.

I think the baby with its limited viewpoint, has offered something to get people to think about the nature of reality.
What is accuracy?What is deemed accurate to one person may not be to another. Place a magnifying glass over it and you are still further from the mark than you were before.

QM has a lot of accuracy, but the problem with 'what the bleep' and similar programs is that it misquotes conventional QM to fund a spiritual agenda. QM is just QM, but many people now think such things as it proves consciousness creates reality (it doesn't suggest that at all) etc, and that's what I see as the problem. A simple google will show thousands of sites misquoting QM trying to convince people science actually backs up their theories of reality (when it doesn't).

[NickJW]

I don't think the movie was trying to make it spiritual, just ltet you see people's opinons on quantum physics from different viewpoints, neurologists, physicists, mystics etc. I found the movie unique and interesting because of this, but in the end its all up to your own opinion. However, you can't count ou the fact that the observer is now part of the equation, even if that does sound a little spiritual.

[MisterJingo]

I don't think the movie was trying to make it spiritual, just ltet you see people's opinons on quantum physics from different viewpoints, neurologists, physicists, mystics etc. I found the movie unique and interesting because of this, but in the end its all up to your own opinion. However, you can't count ou the fact that the observer is now part of the equation, even if that does sound a little spiritual.

Early experiments seemed to suggest that the observer was integral to the experiment ie without the observer there would be nothing. This has been taken to mean such things as the moon only exists if you look at it etc. And this has been used as the basis for many spiritual philosophies.
What I meant is that reality can continue unconsiously, that is, without an observer there is still reality - just nothing to observe it. This can be seen from the current state of the universe ie we can work backwards based on current observations to the first stages of the universes development (ie we can see states previous to observers).
If we follow the belief the the observer is needed for reality to exist, then reality only existed from the moment of first consiousness, and following this logic you can say creationism is true - ie observation created it.

[malganis]

MisterJingo, have you read The Field by Lynne McTaggart? What do you think about it if you have?

[maddutchman]

Mister Jingo I can see your viewpoints and agree with them. I'm taking the more liberal stance that as human trying to understand the divine principle running through all things, there is no known possibility that we can ever get natures laws mapped out with 100% accuracy. We tend to look at things within too small a frame of reference.
I understand as human thought has evolved to include more holistic approaches to things as time goes by, but how do you get a holistic view of the infinite.

I've become more interested in QM only because of a prior interest in spirituality. I've gone from seeing the single synchronous events happening within my life as the cogs in a larger network of turning wheels of cause and effect .Sure as each event happens my picture becomes more and more focused as to the larger web of the grand design. but I guess it what we don't know(and our striving to make the unknown known) that makes us strive to become more conscious, and more aware, beings

[MisterJingo]

MisterJingo, have you read The Field by Lynne McTaggart? What do you think about it if you have?

Hi Malganis,

I haven't read this. But I just looked it up on amazon and it looks interesting so I'll order it and post back my thoughts .

[MisterJingo]

Mister Jingo I can see your viewpoints and agree with them. I'm taking the more liberal stance that as human trying to understand the divine principle running through all things, there is no known possibility that we can ever get natures laws mapped out with 100% accuracy. We tend to look at things within too small a frame of reference.
I understand as human thought has evolved to include more holistic approaches to things as time goes by, but how do you get a holistic view of the infinite.

I've become more interested in QM only because of a prior interest in spirituality. I've gone from seeing the single synchronous events happening within my life as the cogs in a larger network of turning wheels of cause and effect .Sure as each event happens my picture becomes more and more focused as to the larger web of the grand design. but I guess it what we don't know(and our striving to make the unknown known) that makes us strive to become more conscious, and more aware, beings

Hi Maddutchman,

My interest in QM came from similar reasons. I have a deep desire to understand who/what I am, what is mind, self, reality etc.
Although I might sound critical in my posts, I'm not really   . My current position is, the more I learn and experience, the more 'faults', or inconsistencies I see with the current spiritual systems/knowledge. Not having time to write too much now, but I think our current spiritual viewpoints have their roots in a more archiac mindset. What I mean by this is peoples view of reality and the driving forces behind it were very different when astral models, energy system models etc were produced.
We still seem to be using such knowledge, even though our world and reality view has changed drastically. I'm not saying that knowledge is now useless, but I think we are a stage where we can seriosuly start sorting the 'wheat from the chaff' and start making real progress - but this will involve perhaps being a bit critical of our belief systems, and letting go of those ones which are 'outdated'.