String theoryexplanation needed

  • Thread starter ant0
  • Start date
  • Tags
    String
In summary: Basically, String theory is a theory that tries to explain how particles, like protons and electrons, work. quarks are part of the Standard Model, which is a successful theory, but string theory proposes to explain it in a deeper way. There are different string theories that model elementary particles as behaving like different strings, and eventually one of them was unified into M theory. There are some particles that the theory has had success with, like the graviton, but the majority of particles in the Standard Model are still unknown.
  • #1
ant0
6
0
Basically i need educating here! What are the basic concepts, etc of string theory? I heard that it is something to do with explaining how protons act, etc instead of explaining with quarks? Any help will be appreciated, cheers
 
Physics news on Phys.org
  • #2
No, strings do not replace the quark model. Quarks are part of the present day successful theory called the Standard Model. And string theory does not propose to replace that but to explain it. The basic idea is that the quarks, and other elementary particles, are actuallly vibration modes of tiny, very very tiny strings, or other things called branes.

To give you an idea of what a vibration is, a note, such as middle C, is a vibration mode of a string in a piano. That same string has other modes, overtones of C, and each one of those tones is a vibration mode of that string.

So the tiny strings (BTW, string theory doesn't say what they are made of) vibrate in different modes, which are moreover quantized so the modes don't vary smoothly among themselves but come at separate energies, these quantized modes in some way constitute the particles. The way they do that has not really been fully explained by the string theorists, but they insist they are making progress and will be able to explain it real soon now.

So bottom line the quarks would still be used, just as Maxwell's equations of electromagnetism are still used in spite of the development of quantum electrodynamics, but another level of understanding would have been added.
 
  • #3
bump, any more simple in a nutshell explanatons of string theory?
 
  • #4
another questoin i have: What was the original super gravity theory(s) that were replaced in the mid 1980s by string theory? Can anyone explain them? Was it to do with infinities of energy or something? I'm a tad confused here
 
  • #5
I thought that string theory was called string theory because the elemetary sping 1/2 particles could be described by equations that are similar to the equations that describe the motions of n dimensional strings or membranes.

This leads to a natural terminology for these elementary particles including a string as an elementary particle, and qualities such as tension or length which are not actually length or tension in a physical sense, but instead correspond to positions in the equations that describe the particles.

Since the inception of string theory, there have been developments of several string theories, which model elementary particles as behaving like different strings - for example as closed loops or allowing for open strings instead.

String theory has also been expanded to include particles with integer spin. These expanded theories are referred to as superstring theory.

The existence and variety of string theories has led theoretical physicists to consider the possibility that they are all aspects of a larger theory that includes them. This larger theory is referred to as M theory.
 
  • #6
Nate, there are some misunderstandings in your account.

First, spin 1/2 particles (fermions) could only be incorporated into string theory by employing supersymmetry, in which each boson has a corresponding fermion and vice versa. This superstring theory quickly broke into five theories based on different gauge groups. Eventually the discoverey of dualisms unified them again in the 11-dimensional M-theory, of which Matrix theory is the currently most active representative.

In all of this, the actual representation of low energy particles as we understand them, in the standard model, has been an ever receding foxfire. The only particle that the theory has really had any success with is the graviton. Unless you want to count the tachyon.
 

1. What is string theory and why is it important?

String theory is a theoretical framework in physics that attempts to reconcile general relativity and quantum mechanics by proposing that the fundamental building blocks of the universe are not point-like particles, but rather tiny, vibrating strings. It is important because it has the potential to unify all of the known forces in the universe and provide a more complete understanding of how the universe works.

2. How does string theory differ from other theories of the universe?

String theory differs from other theories, such as the Standard Model, because it posits that the fundamental building blocks of the universe are not point-like particles, but rather tiny, vibrating strings. This allows for a more complete and elegant description of the universe, as it can potentially unify all of the known forces and provide a more complete understanding of the nature of matter and energy.

3. What evidence supports string theory?

Currently, there is no experimental evidence that definitively supports string theory. However, many physicists believe that it is the most promising candidate for a theory of everything, as it has the potential to reconcile many of the discrepancies between general relativity and quantum mechanics. Additionally, certain predictions of string theory, such as the existence of extra dimensions, have not been ruled out by experiments.

4. Are there any challenges or criticisms of string theory?

Yes, there are several challenges and criticisms of string theory. One of the main challenges is that it has not yet been possible to test the predictions of string theory through experiments. Additionally, some critics argue that string theory is too abstract and relies too heavily on mathematical elegance rather than empirical evidence. There are also alternative theories, such as loop quantum gravity, that offer different solutions to the issues that string theory aims to address.

5. Is string theory the only theory of everything?

No, string theory is not the only theory of everything. There are other proposed theories, such as loop quantum gravity and supersymmetry, that also aim to unify the forces of the universe. However, string theory is currently the most well-known and widely studied theory of everything, and many physicists believe it has the most potential for success.

Similar threads

  • Beyond the Standard Models
Replies
31
Views
2K
  • Beyond the Standard Models
Replies
5
Views
1K
  • Beyond the Standard Models
Replies
4
Views
1K
  • Beyond the Standard Models
Replies
4
Views
2K
Replies
47
Views
4K
  • Beyond the Standard Models
Replies
0
Views
902
  • Beyond the Standard Models
Replies
3
Views
1K
  • Beyond the Standard Models
Replies
28
Views
2K
  • Beyond the Standard Models
Replies
1
Views
1K
  • Beyond the Standard Models
Replies
13
Views
1K
Back
Top