String Theory

[Ashish]

can anyone explain me the basic of String theory

[thedarkshade]

Well... the very basic thing about string theory is that string theorists think that everything (literally everything) is made of strings (little vibrating strand of energy), but string theory is quite a wide concept.

I can provide you some links if you want, where you can watch the whole three parts of "The Elegant Universe", which explains in a very good way what string theory is about! If you are interested just let me know!

 

Cheers,

Shade!

[Ashish]

Well thanks for the reply

 

 

and I've seen the video about which you are talking about

but can you tell the term used here "string " whats that

[thedarkshade]

As you may know, everything is made of atoms. An atom consists of a nucleus and the electrons orbiting the nucleus. Nucleus is made of protons and neutrons. Neutrons and protons are made of quarks, and according to string theory quarks are made of some extremely small vibrating strand of energy which vibrate in different ways, and these are called strings. String are thought to be the most fundamental particles that build everything!They are called strings simply because string theorists think that they 'look' like strings (although there's something about the membrane stuff)!

[ydoaPs]

An atom consists of a nucleus and the electrons orbiting the nucleus.

NO! Electrons do not orbit! If the electrons orbited the nucleus(like the Bohr model), then they would give off radiation since they are charged. This would lower their energy and they would fall into the nucleus.

[thedarkshade]

This would lower their energy and they would fall into the nucleus.

OMG! Tell me you're joking?! They have strict orbits and move from that orbit only when energy is given to them, otherwise they keep moving on their own orbits!

[Daecon]

Are they like little pinpoints orbiting the nucleus at a set distance away, like a miniature solar system, or are they waves, swirling about the nucleus as a given distance like a... um, like in a sci-fi show where you fire a gun at a spherical force field and see an interference pattern spread out from the point of impact and reverberate around...?

[thedarkshade]

Yeah, something like that Transdecimal...

[fredrik]

can anyone explain me the basic of String theory

 

Decide for yourself if it makes sense, but check http://www.superstringtheory.com/basics/index.html

 

/Fredrik

[ajb]

Read the very good notes by Richard J. Szabo; BUSSTEPP Lectures on String Theory.

 

There is also a book published based on these notes.

 

If you want other books and references I can supply some.

[Severian]

I have bad memories of BUSSTEPP.

[ydoaPs]

OMG! Tell me you're joking?! They have strict orbits and move from that orbit only when energy is given to them, otherwise they keep moving on their own orbits!

No, I'm not. They have strict energy states, but they do not orbit. Click here to learn more.

Unlike the fixed orbit conceptualization, an electron cloud bound in an atom is not predicted to collapse towards the charge nucleus, while emitting photons, in order to minimize the sum of electric potential and kinetic energies, since the "cloud" would gain too much kinetic energy, as required to conserve uncertainty. The smear obeys Schrödinger's equation (see also Erwin Schrödinger[/url']), which has discrete solutions at differing energy levels.

[Realitycheck]

No, I'm not. They have strict energy states, but they do not orbit. Click here to learn more.

 

So, essentially the electrons still travel in orbitals, just not orbits.

[foodchain]

So, essentially the electrons still travel in orbitals, just not orbits.

 

Its called the electronic configuration and I think it also ties into the periodic table. You have certain values if you will in which an electron can "occupy". This then leads to a probability of finding the electron I think in that certain orbital. This ties into the Pauli exclusion principle for shell filling or is that the Hund rule. So say you have iron, its electron configuration as cut and pasted from wiki is [Ar] 4s2 3d6. This tells you how many electrons and where they are at and a I think the closest living relative which in this case is argon.

 

I don’t know why its still called an orbital. Lots of QM goes back to Planck and really you have discrete values of energy. So a simple way to look at it is it takes so much energy to eject the first electron, and so fourth. I think this even has a name I just cant remember it. The thing about it is if you could say exactly where an electron was you would have to know both position and momentum at the same time. The electronic configuration and related variables are all products of QM I think. A good example of why QM works is because it could explain random decay and why the electrons did not simply crash into the nucleon.

 

If you go through the electronic configuration for an element it typically leaves you with the reactivity or amount of electrons and element has, or what shell is not filled for instance.

[ajb]

I have bad memories of BUSSTEPP.

 

You have got to say more than just that!

 

I have never been to BUSSTEPP.