If strings are vibrating all the time, then...?

[pioneer]

One of the problems with string theory is too many dimensions. The reason for this is the assumption of 2-D strings. If the strings were made more 3-D, it would be possible to reduce the number of dimensions. One possible 3-D string, is the continuous single string winding, like inside of a golf ball.

 

Let me explain why the 2-D assumption leads to extra dimensions, using a simple analogy. We can make all colors blending blue, red and yellow. If we use all three (3-D), we can do this on one graph. If we only allow two at a time to be consistent with 2-D, we need three graphs to plot all the combinations of two colors. We also need another graph to make white and neutral gray, since these will not appear with just two primary colors. But it doesn't stop there. There are tan-grays, orange-grays, blue-gray, etc., each of which, to stay 2-D may require their own separate graph. The result is a fluff affect requiring more graphs or more dimensions.

 

If we assume all colors can be made using all three or 3-D, we use less graph paper. It only takes one piece. All the extra dimensions are a mathematical necessity due to the 2-D assumption of strings. Maybe the filament winding may or may not be the best model, but any real good 3-D string model should allow the number of dimensions to collapse back to four.

[thedarkshade]

We could cope with extra dimensions somehow, but still the difficulty stand on being unable to prove it (experimentally or observe). Very tiny stuff.

[ajb]

One of the problems with string theory is too many dimensions. The reason for this is the assumption of 2-D strings. If the strings were made more 3-D, it would be possible to reduce the number of dimensions. One possible 3-D string, is the continuous single string winding, like inside of a golf ball.

 

Let me explain why the 2-D assumption leads to extra dimensions, using a simple analogy. We can make all colors blending blue, red and yellow. If we use all three (3-D), we can do this on one graph. If we only allow two at a time to be consistent with 2-D, we need three graphs to plot all the combinations of two colors. We also need another graph to make white and neutral gray, since these will not appear with just two primary colors. But it doesn't stop there. There are tan-grays, orange-grays, blue-gray, etc., each of which, to stay 2-D may require their own separate graph. The result is a fluff affect requiring more graphs or more dimensions.

 

If we assume all colors can be made using all three or 3-D, we use less graph paper. It only takes one piece. All the extra dimensions are a mathematical necessity due to the 2-D assumption of strings. Maybe the filament winding may or may not be the best model, but any real good 3-D string model should allow the number of dimensions to collapse back to four.

 

1) Strings are one dimensional not two dimensional.

 

2) The extra dimensions in string theory arise when you quantise the classical string. I don't understand how you argument reflects this.

 

 

as an aside, Zephir has an addenda of some kind...

[Zephir]

.. Strings are one dimensional not two dimensional...

...the string theory is using the strings of arbitrary number of dimensions (3, 5,...). Don't expect, you'll ever understand the string theory terminology.

[ajb]

MMMM, I am reasonably well versed in string theory. Well, just the usual graduate courses in string theory. So no expert.

 

Ok, you can formulate (classical) string theory in any dimensions.

 

The dimensions are fixed when you quantise the string. The reason is that the resulting quantised theory has anomalies unless the dimensions are 10 for the superstring and 26 for the bosonic string The reason is technical, but we can discuss it. Or I could point you towards my MSc project on the topic.

[fredrik]

I'm certainly no string expert either but it seems you're talking about "branes", like a generalisation of strings?

 

As far as I know I'm with ajb that if you just say "string" it refers to a 1 dimensional extended object (embedded in some background space of varying dimensionality).

 

A p-brane is the generalisation of string to a p-dimensional object.

 

0-brane is a point.

1-brane is a 1-D STRING.

2-brane is surface (2D-membrane)

and so on.

 

Like a string, these higher dimensional objects can also be thought to be embedded in higher dimensional spaces. But of course if you replace the string with a membrane, I figure the constraints for the external dimensionality is expected to differ.

 

If we take the normal string idea to replace points with strings, the logical continuation is to repeat the induction, and ask what it means if we inflate the string to a plane, and so on. And are there brane theories related to ordinary string theories? (By somehow trading internal degrees of freedom for "space-time" degrees of freedom?)

 

p-brane -> (p+1)-brane

 

Stringers refer to part of the relations between different theories involving p-branes of different p:s as p-dualities.

 

A very *naive* consideration, is that you can picture a highly energetic oscillating string, perhaps depending on the situation it would not be entirely trivial to distinguish this object from a not so energetically vibratiing membrane because you might not be able to distinguish the oscillations of a lower dim object from an extended object, if you imagine a string with the same mass or total intertia as the membrane. The plane in which you have dynamics might effectively map out another dimension. And if you try to formulate a real measurement problem, on how to determined if you've got a plane of a string it seems that one wouldn't expect it to be easy.

 

/Fredrik

[ajb]

-1 brane is an instanton

[antimatter]

First, strings ARE energy, they are a representation of it.

 

Second, strings don't vibrate they way you think they do when they are 11 dimensional.

[ajb]

First, strings ARE energy, they are a representation of it.

 

Second, strings don't vibrate they way you think they do when they are 11 dimensional.

 

really? Because I thought you could do a Fourier decomposition. Oh, wait, yes you can!

 

??????

[Riogho]

11 Dimensional?

 

Hold on here, I thought were were talking string theory, not superstring theory, here.

 

If we are into superstrings we are talking slightly more complex, and more then WAY over my head

[ajb]

"string theory" would be the encapsulating theory of strings, both bosonic, fermionic and super (both fermionic and bosonic). Not that I ever hear much about pure fermionic strings.

[mmzaj]

well , as i understand it , the fact that strings don't shrink due energy consumption is related to the infamous uncertainty principle .... as a string vibrate , classically it would shrink to a single point , but somewhere in the middle there will be a balance between the string's size , and it's energy , and it will continue to vibrate while maintaining a specific size , unless an external energy is pumped into it .

[pioneer]

Absolute zero implies no temperature or no energy. Due to the mass-energy equivalence there can not be any matter either. The perfect vacuum without energy can reach absolute zero. This suggests that matter disappears at absolute zero, since it presence will not allow a perfect vacuum. It loosely suggests that the center of a black hole may be at absolute zero since that temperature requirement would also preclude matter-energy.

 

Look at the black hole this way. Gravity is putting the squeeze on matter to ring out all the energy that is contained in it. The energy can't escape but also gets rung out. Infinite wavelength energy forms at the event horizon but this is not technically energy. The product of wavelength and frequency needs to multiple to C. One can't get C with by multiply anything by infinity. That is a by-product of absolute zero since it is neither matter or energy and therefore has no impact on the temperature scale.

[Klaynos]

The perfect vacuum without energy can reach absolute zero.

 

Sorry but there's no such thing as a perfect vacuum, it's a non-physical situation. Pesky vacuum fluctuations!

[Riogho]

The problem with a perfect vacuum is that it is a classical concept.

 

ZPE is a QM concept, they don't mix.

 

So if you're working with anything in the realm of the small, a 'perfect vacuum' or even 'absolute zero' are meaningless.