Exploring String Theory - A Conversation for Everyone

[DANTHEMAN]

Firstly, I'm new here. I looked around a bit to see if there was another thread about String Theory. Didn't see any so I said what the hey. I certainly hope that this subject hasn't been beatin to death.

I'm not a physicist, nor am I overly educated. But I like to think that I understand physics, relativity, and quantum mechanics better than the average bear.

To the best of my knowledge. Strings are supposed to be the basic building blocks of everything. They resonate just like the strings on a stringed instrument. And somehow, the way they vibrate contains all the stuff of the universe. (told you I wasn't very educated)

Also, If I understand correctly. There are multiple dimensions that are explained in string theory. Along with the thought that perhaps each string is somehow connected to some sort of a membrane. And that each membrane is a separate universe unto itself.

So anyway, I'd like to hear all of your thoughts.

I see that this forum has some educational functions. So if you could provide some for the average joe that is just curious, that would be much appreciated!

 

[ZapperZ]

You need to look CLOSER. If you look in the PHYSICS section of PF, the LAST of the 6 different categories is a section called "Strings, Branes, & LQG". Bingo!

Zz.

 

[DANTHEMAN]

Yep, I only checked the quantum forum. Totally my fault.

 

[quantumdude]

Dan,

I've scooted your thread over to our String Theory section. We do in fact get this kind of "What is string theory?" question fairly frequently, and it really is a monumental task to answer the question. So I'll tell you what we usually tell people when they ask, "What is X", where X=strings, GR, QM, etc:

Get specific!

The way to explore a subject is one aspect at a time. Check out the following website and see if there's anything in particular that you'd like to discuss.

http://www.sukidog.com/jpierre/strings/

Cheers, and welcome to PF,

Tom

 

[DANTHEMAN]

I'll check out that site, and try to make my 2nd thread better than my first.

Also, thanks for moving my thread to where it belongs.

Dan.

 

[quantumdude]

Feel free to continue right along in this thread, if you like. It could develop quite nicely, one module at a time.

 

[Nate.]

I want to introduce myself and say that I'm kind of in the same boat as DANTHEMAN. I registered a few months ago and have been lurking ever since. I figured this was as good a thread as any to make a formal introduction.

To be brief, I'm an armchair physicist. My most advanced formal training is college level physics I and II. After that it's been all Greene and Kaku.

I'll try not to annoy you more advanced types with silly questions. I'm about as well of a seasoned google and wikipedia veteran as you'll find.

Anyway, Hello.:)

 

[ohwilleke]

Real quick version:

1. Sting theory makes virtually no testable predictions, but it looks very like it ought to reproduce the electro-magnetic force, strong force, weak force and gravity with associated particles because string theories are based on a part of algebra known as group theory which can be broken into parts that a strongly suggestive of those forces and the associated particles.

2. Something this beautiful can't be wrong, or so have reasoned a huge number of theoretical physics graduate students.

3. But, the math is really hard, and you need lots more than four dimensions to do anything that makes any sense. So the string theory community is stumped at the moment, although trying very hard to figure out how to turn their equations into something real. One way that they have done so is with "Brane Theory" because one way to model gravity that seems to work is to have lots of gravitational force seep out of the universe we know and love into other dimensions, while we and almost all matter and photons are stuck on the 4-D equivalent of a soap bubble's surface.

4. Meanwhile, a little dissident colony of string theorists have broken off and basically said, screw the ambitious project of explaining everything with strings, we're going to try to explain gravity alone using a loop variety of string and playing around with the underlying structure of space-time by making it discrete rather than continuous in a really clever kind of way that makes very few assumptions about the nature of space time. These are the Loop Quantum Gravity (LQG) people.

5. The LQG people aren't ready for prime time either, but they're doing better. They have recently graduated from models with two dimensions in space and one in time, to models that kinda look like real life, and they are starting to apply their theories to the big bang and black holes, and they are starting to be able to make some predictions. String theorists, as a result, are green with envy.

But, nobody has a theory that makes strong predictions which have been tested empirically, so this could all be a bunch of B.S. Smolin has a nice long paper with technical details on the state of both string theory and LQG which is floating around in a fairly recent link someplace. Maybe Marcus, our resident librarian, could dig it up for you. It is tough going, but, the trouble with string theory and LQG and most modern physics, for that matter, is taht it has really wicked hard math and involves a lot of technical terms which are hard to follow. So, reading papers like this is not for the faint of heart, and there isn't a lot of middle ground between the heinously difficult stuff and the easy stuff ("The Elegant Universe" is a popular one that tries to bridge the gap).

 

[Chronos]

The LQG paper usually referenced:

http://arxiv.org/abs/hep-th/0408048
An invitation to loop quantum gravity
Authors: Lee Smolin

Here is a decent string intro that won't immediately induce a coma:

http://www.arxiv.org/abs/hep-th/0207249
Introduction to String Theory
Authors: Thomas Mohaupt