# String theory Formula

Discussion in 'Physics & Math' started by ColdFusion, Jan 22, 2003.

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1. ### ColdFusionRegistered Senior Member

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What is the formula of the string theory?
Is there a general formula like the E=mc^2 in Einstains theory?
I searched the web but I couldn't find anything usefull or understandable. I'm eighteen and finishing highschool this year, but I want to learn

ColdFusion

3. ### chrootCrackpot killerRegistered Senior Member

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2,350
*ROFLMAO*

There is no single formula for ANY theory.

- Warren

5. ### ColdFusionRegistered Senior Member

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58
Someone told me there is a formula of the string.
What is it?

ColdFusion

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8. ### Fraggle RockerStaff Member

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24,690
String Theory

As I understand it:

String theory is an attempt at the GUTE (Grand Unified Theory of Everything). Gravity does not fit into existing models of the universe very well. Accounting for it destroys/prevents simplicity, symmetry, elegance.

In string theory, the elementary... uh, thing(?)... is the string. Every particle, force, wave, etc. is decomposed into strings.

The reason for choosing the string as the basis for the theory is that strings vibrate. Picture the strings on a musical instrument, all clamped at the same length between the bridge and the nut, (yes, fellow musicians, we know that's not quite true but non-musicians don't) and each adjusted to a specific tension. They vibrate at distinct frequencies that can be calculated by one simple and uniform equation.

By introducing vibrations determined by these parameters into the model of the universe, the four forces (gravity, EM, and the strong and weak nuclear forces) suddenly fall into one pattern and can be described by formulas that are simple, symmetrical, and elegant in comparison with our old model.

I'm no physicist, so I can't go into this any deeper. I don't know whether String Theory is simply the next step in the evolution from Newton to Einstein etc., or whether it diverges from some of their postulates. The one rather short article that I was able to read completely without my brain seizing up expressed great hope that String Theory will generate a model of the universe with only the four dimensions that my brain already understands, instead of the eleven or fourteen that I have seen suggested in older research. We should always be wary of scientists trying to prove a theory they like instead of trying to discover the truth, and I'm in no position to tell which camp these guys are in.

For all I know you may be six years ahead of me and what I've just said is bonehead elementary or just plain incorrectly stated. If so forgive me. If not, I hope I have helped. A Google search on the topic will keep you busy for quite a while.

9. ### blobranaRegistered Senior Member

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2,214
I think you gave a great explanation for it ....

But can i add that STRINGS may have notes (vibrations), they may be loops, open ended , tangles or membranes(!)... It may even be the KNOTS that they form that give rise to everything...

Of course string theory has been improved to give M-theory.

10. ### rohitvashistha2003Registered Member

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string theory

i agree with rocker. he is right. string theory is simply an attempt to merge general relativity theory and the quantum theory. the general relativity is the theory for big thngs (how big are the big things) and quantum theory is the theory of small things. here big is interplanatory and small is interatomic. i can suggest a very good book- "the elegent universe written by brian green". go through that book. the best part of this book is that you need not have to understand the most dufficult methamatics of the string theory which involve more then four dimensions. he have explained everything lucidly.

have a nice time with this beautiful theory

11. ### AlphaNumericFully ionizedRegistered Senior Member

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6,702
While it's true that there is no "This is [the formula for string theory!", there are formulae which are central to it. In any quantum field theory or relativity based theory you generallly get the majority of your information about the system from the Lagrangian or Hamiltonian, which tell you the energies of various things, kinetic and potential. In QED you have

$\mathcal{L}_{QED} = \bar{\psi}(i\gamma^{\mu}\partial_{\mu}-m)\psi + ie\bar{\psi}\gamma^{\mu}A_{\mu}\psi$

From this you can work out the equations of motion, the Feynman rules and start calculating scattering amplitudes (ie how particles bounce off one another). In string theory it's not quite as straight forward but there is a Lagrangian for how strings interact, known as the Polyakov action and there's a generalisation of it to branes (ie higher dimensional objects).

$S = \int d^{n}\xi \, \mathcal{L} = \int d^{n}\xi \, P(G_{ab}) = \int d^{n}\xi \, \frac{\partial X^{\mu}}{\partial xi^{a}}\frac{\partial X^{\nu}}{\partial \xi^{b}}G_{\mu\nu}$

P(G) is the pullback of the space-time metric into the n-brane world volume.

When you start considering fields living on the branes or strings it gets generalised to the DBI action where P(G) goes to $P(G_{ab}+2\pi \alpha' F_{ab})$ where $F_{ab}$ relates to generalisatoions of electromagnetic fields.

Then you can go into more specific cases and construct Type IIA, IIB, I, E8xE8 and SO(32) string actions in 10 dimensions, supergravity actions in 11 or less dimensions and even the M theory action. Each are interrelated by dualities, compactifications, particular limits and a slew of other things which if you don't know about the different string types already it's pointless me explaining it.

And buried in all of this are the more familiar things like $E^{2} = m^{2} + |p|^{2}$, from special relativity and $G_{\mu\nu} = 8\pi T_{\mu\nu}$ from general relativity, the former is an input of string theory and the latter is an output.

12. ### Beyond the BoxRegistered Senior Member

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String Theory

For those of you in search of the one inch long "theory of everything", please read this quote from Dr. Michiu Kaku regarding string theory:

"You might have heard me speak about the equation that eluded Einstein for the last 30 years of his life: the one-inch equation that will in a sense summarize everything we know about the physical laws governing the universe we live in. I believe that one day, perhaps the destiny of all intelligent life in the universe may hinge on this equation. Finding it is the goal of a lifetime."

13. ### Cortex_ColossumBannedBanned

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193
We are not the only life in the universe. There are many diverse life out there.

Last edited: Jan 19, 2012
14. ### Fraggle RockerStaff Member

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He said, "all intelligent life."

In any case, to expect to be able to decompose the universe down into a sound bite is human arrogance at its finest. Why would one of the fundamental laws of nature be: "Everything must be fairly easy for humans to understand"?

15. ### James RJust this guy, you know?Staff Member

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36,255
This thread is 9 years old. Start a new one if you're still interested.