What makes the strings in string theory "vibrate"?

QuantumKitty

Does string theory include or say what is responsible for making strings vibrate? Also, why do the strings not all vibrate in the same pattern; what makes a string "choose" one pattern over another?

Bob_for_short

It's energy. All depends on energy.

QuantumKitty

But how does the energy "choose" what pattern to vibrate in? If the answer depends on how much energy a particular string has, then why do some strings have low energy while others have higher energy?

Bob_for_short

Energy-momentum is something with which the species exchange while interaction. The total energy is distributed over species in some way and this distribution changes due to interactions.

gesseg

As I see it God (or life energy) makes the strings vibrate. They vibrate at particular frequencies in order to give specific properties to particles in the quantum world.

Naty1

"Does string theory include or say what is responsible for making strings vibrate?"

I have not yet seen that....only that the math reflects vibrational energy patterns. It's not surprising on the surface anyway: I have thought of it reflecting Heisenberg uncertainty, like a particle confined in an ever smaller volume becoming more and more energetic...

String vibrational patterns theoretically reflect in part geometries (sizes and shapes) of extra compactified dimensions...more dimensions means more vibrational patterns....extra dimensions we can't observe determines particle properties that we do!!!

its analogous to how a violin string vibrates, for example...tension,length,geometry....except a violin string can be made of different materials, strings not.

but the pertubative equations of string theory have so far not revealed the shape and size of the extra dimensions...

Above outline from Brian Green's FABRIC OF THE COSMOS, 2004

mjacobsca

What keeps the strings vibrating after all this time? If the strings got their initial vibration pattern via some distribution of energy, how would they keep this vibration pattern since the energy that was present around the string is now different? Shouldn't the vibration slow down at some point? Or shouldn't the vibrating pattern change with time or via collisions with other strings?

Fra

I can't speak for how a string theorists sees this but although I do not like the string program as it stands, it does have some plausible traits. But to speak for myself, analysing these nice traits, one sees that they have really nothing to do with strings per see, and thus aren't specific to string theory. The way string theory could make sense to me, is not to actually think of this as a regular "mechanical string".

There is a possibilty to cast into a more information abstraction, where you can see the "string" as an observer, and the microstructure of this (be it a string, brane or systems therof), then could represents a coded form of knowledge this object has about it's own environment.

Then a "vibration" could be seen as just a state of oscillation, or "state of uncertainty" of the string has. Then one could argue that there is no reason for someone to revise an opinon until it's faced with contradictory information.

To get away from the IMO silly analogy of a oscillating mechanical strings and the issue of friction etc, here is anothre way of seeing it.

In an environment where there is constant interactions, a stable information state (be it a state of motion or whatever) is a state where the ambient incoming information is consistent withe what is encoded. Then no change is made. But clearly, if the anvironment changes the information state is generally not stable, and the information state (string modes for example) will destabilise and recover a new equilibrium.

These intuitive argument is a general view though that makes use of an information state, beeing "excited" and "revised" in the light of new evidence. It is not specific to string theory at all.

Instead the question that one would ask form this reasoning is : why would a string be the obvious fundamental microstructure to represent information? Why not a membrane? or a sphere? Apparently these questions is what the string community has been lead to eventually, not because of general arguments but beacuse the original idea didn't lead to a unique theory.

A "democracy of observers" is the sound way I see most of the dualities in string theory. And a string would generally SEE the world differently than say a membrane, but why would one be more fundamental than the other? Is a string "simpler" than a membrane? Maybe, but this simplicity certainly needs to be quantified. Could it be that simplicity is context dependent, so that somethings a string is the simplest representation, and sometimes a membrane is, and sometimes it could maybe even be a discrete network?

In this general view, the choice of representation, strings, branes, networks, is really not the important thing. I think it's what they represent and how they evolve that is interesting. In that sense I think string theorists started in the wrong end.

/Fredrik

arivero

Existence. Or, said otherwise, ask what could be the responsible for the strings to do NOT vibrate.

Actually, vibrate is sort of misnomer. Most strings live in the fundamental state, so I would guess that a rigid rotation is a better image.