Understanding String Theory: A Beginner's Guide

[bondinthesand]

I have, for a couple of weeks, been looking up what string theory is all about but i can never actually really grip it. Is there anyone one out there who can give me a simple explanation of it?

 

[DaveC426913]

Is there anyone one out there who can give me a simple explanation of it?

If they did, it would be wrong. There's no "simple" about it.


What is it specifically that you're having trpouble with?

 

[bondinthesand]

I have trouble with the idea of all the different dimensions.. i just can't grip it idk??

 

[sndtam]

Did you read The elegant Universe by Greene?

 

[DaveC426913]

Did you read The elegant Universe by Greene?

That was going to be my suggestion too.

Though many pros dismiss it as pop sci, it was one of the most enlightening physics books I've ever read. My brain is measurably larger after reading it (twice).

 

[bondinthesand]

thx for the suggestion i have not read that but i would love to! but I am only a jr in high school i probably would get lost but if you have any others i would love to know. i love reading about this stuf

 

[ralilu]

my copy of "the elegant universe" shud be in my mailbox on the 28th. How deep does it go in trying to explain all this modern physics? Does Brian Greene make an effort to make the average reader understand or is it like Stephen Hawking who doesn't make much effort?

 

[bondinthesand]

i have read Stephen's book and I found it was very good and i was not that bad to read

 

[ralilu]

i read it when i was a junior in high school. "Imaginary time" and "sum of histories"... are concepts that arent that easy to grasp and he doesn't make much of an effort to explain them.

 

[humanino]

i read it when i was a junior in high school. "Imaginary time" and "sum of histories"... are concepts that arent that easy to grasp and he doesn't make much of an effort to explain them.

There may something you are missing here. HE is making the ENTIRE effort in writing the book so that YOU can be lazy enough not to understand anything but FEEL like you understood something.

 

[DaveC426913]

my copy of "the elegant universe" shud be in my mailbox on the 28th. How deep does it go in trying to explain all this modern physics? Does Brian Greene make an effort to make the average reader understand or is it like Stephen Hawking who doesn't make much effort?

He stays away from math and formulae pretty well. It's aimed at the knowledgeable layperson. But it's still quite brain-stretching. I had to read it sloooowwwly.

 

[Fra]

I have, for a couple of weeks, been looking up what string theory is all about but i can never actually really grip it. Is there anyone one out there who can give me a simple explanation of it?

Does this help? - http://www.superstringtheory.com/basics/index.html

/Fredrik

 

[ralilu]

There may something you are missing here. HE is making the ENTIRE effort in writing the book so that YOU can be lazy enough not to understand anything but FEEL like you understood something.

Thats the thing. I spent my hard earned cash on his book to understand everything in the book. Stephen Hawking is a brilliant physicist ,but not necessarily a brilliant teacher. Each one is entitled to their own opinion.

 

[ralilu]

He stays away from math and formulae pretty well. It's aimed at the knowledgeable layperson. But it's still quite brain-stretching. I had to read it sloooowwwly.

Cool. i will enjoy reading it if there's a bit of a challenge to it.

 

[sndtam]

You can also try Universe in a Nutshell by Hawking.Its very easy to grasp.

 

[ralilu]

yeah, i read Universe in a Nutshell. Its a lot better than Brief History of Time. I guess the main problem (for me) with Brief Hist...is that its brief.

 

[QuantumKitty]

I suggest reading Lee Smolin's The Trouble With Physics. It gives an in depth, easy to grasp understanding of what string theory is, and also goes into what the theory has done for and to science in general. I enjoyed it greatly.

 

[ralilu]

I am busy reading The Elegant Universe by Brian Greene and so far i think its the best book I've read on this subject. If (big, huge if) i still have queries i'll check out Lee Smolin's book.

 

[DaveC426913]

I suggest reading Lee Smolin's The Trouble With Physics. It gives an in depth, easy to grasp understanding of what string theory is, and also goes into what the theory has done for and to science in general. I enjoyed it greatly.

I could not get through it. It went in a completely uninteresting direction for me.

 

[seerongo]

I am pleased to see so many suggestions about Greene's book "The Elegant Universe" because coincidentally I am about half way through it now and just came upon this thread. It covers more than just String Theory by starting with a pretty good review of Special and General Relativity and a bit (not much) of QM. I find it a bit proselytizing about Strings at times, but I can get past that and maybe it's justified anyway.

My question is to the experts here who have read Green's book. The book was written ten years ago now (1999) unless there is an updated version. Considering that String Theory is such a moving target, is this time period important to the layperson's approach to the subject, or have there been important developments in the meantime?

 

[humanino]

I would definitely not call myself an expert, but I am pretty sure Lisa Randall provides a much better account. I guess the best is to read both to realize the difference.

 

[seerongo]

@ Humanino: Thanks for the tip about Lisa Randall's book. I just requested it from my library. We'll see how that one goes!

I probably will look at Lee Smolin's "The Trouble with Physics" after that. I've actually been avoiding that one because it sounded like it may be too negative and philosophical for my taste. Based on some some other pieces by him and blogs I've read, it sounds as if he is getting discouraged, like he doesn't know where to hang his hat anymore, although I may be seeing too much into all that. But, it may counter some of Greene's enthusiasm for strings, and I do like to know of the problems confronting these cutting edge models. To that end, I find some of the debates on this forum to be helpful, sometimes confusing, but always entertaining!
Ron

 

[humanino]

@ Humanino: Thanks for the tip about Lisa Randall's book. I just requested it from my library. We'll see how that one goes!

I'd be interesting to know how you compare the two books.

 

[Fra]

I probably will look at Lee Smolin's "The Trouble with Physics" after that. I've actually been avoiding that one because it sounded like it may be too negative and philosophical for my taste. Based on some some other pieces by him and blogs I've read, it sounds as if he is getting discouraged, like he doesn't know where to hang his hat anymore

I've read all smolins 3 booksbooks: 3 roads to QG, trouble of physics and the life of the cosmos.

All three books have a large overlap IMO, and all three books contains several parallell implicit topics. Many of them are "research political", some of them are about Smolin's personal adventures and career, but the more interesting topis are that he is trying to put forward often philosophical but still well justified arguments that should encourage the reader to look for new ways of thinking. Somehow this comes to it's peak when he discusses his evolution of law and his example of this, his Cosmologial Natural Selection hypothesis.

I personally think there is one major overall message in all smolins books which I consider to the main point, and that is to encourage the reader to be critical of current frameworks and open for possibilities, and not put all eggs in one basket, because the scientific progress needs both a selection and variation. I personally think variation and diversity should not be confused with irrationality or not knowing where to lay your hat.

/Fredrik

 

[Naty1]

All the above books have their pros and cons; Brian Greene and Lee Smolin are hard to beat for qualitative reading. I personally found Lisa Randall's WARPED PASSAGES excellent but so detailed I just realized I never finished the last 80 pages or so.

Smolin's explanations, I think, are excellent and clearly explained and THE TROUBLE WITH PHYSICS seemed to me a reasonably balanced dicussion about what we know and what we don't know. It is one man's opnion about physics today.

While some authors different books do overlap, and different authors as well have overlap with other authors, getting different explanations of the same phenomena can lead to "aha" moments.

Michio Kaku's Hyperspace, while relatively light on string theory, has enough of interest to be very worthwhile: He lays out in diagram form of an Nx N matrix the relationships between relativity, Maxwell's equations, and the weak and strong force (and others) in what I found to be a fantastic qualitative insight into the implications of N dimensional space.

 

[Naty1]

FRA posted:

I personally think there is one major overall message in all smolins books which I consider to the main point, and that is to encourage the reader to be critical of current frameworks and open for possibilities, and not put all eggs in one basket because the scientific progress needs both a selection and variation

I agree: but for a slightly different reason. Never has consensus "main stream" science been completely correct...(Science is difficult stuff!) Not Ptolomey, Not Erastothenes, not Newton, not relativity, that protons and neutrons are "fundamental", hydrogen peroxide is antiseptic, Vitamin C prevents colds, the universe consists of only "common" matter, atomic weights are just a curosity, black holes are impossible, there are only three plus one dimensions, the universe is static, we can know everything, and on and on... anyone mired in ONLY traditional beliefs and science is unlikely to garner new fundamental insights.

 

[Naty1]

Is there anyone one out there who can give me a simple explanation of it?

If you start from the premise that instead of infinitesimal point particles, the basic constitutents of matter are actually one dimensional vibrating strings of energy ...extended objects, that is a start. Vibrational patterns of the strings create the particle properties we observe, like mass, energy,spin. Because they are extended entities not point particles, infinites are avoided.

The only way those strings can be constrained to vibrate in such a way as to produce mathematical characteristics which include experimentally observed properties around us is to constrain their vibrations via the shape and size of extra curled up dimensions.

That's the "good news"; the "bad news" is after maybe 20 years of prodigious effort there are still many bugs to work out...string theory is still unfinished and untested. For example, the best understood string theories operate in a fixed spacetime background...so they can't reconcile QM, gravity and particle physics which was the hoped for result of string theory.

 

[DaveC426913]

Because they are extended entities not point particles, infinites are avoided.

I'll elaborate on this. The avoidance of infinities allows the reconciliation of SR and QM, which is one of the Holy Grails of our time.

 

[Fra]

Never has consensus "main stream" science been completely correct...

That's true. But if you, like I do, see strong connections between physical processes, and scientific informational inference processes, then there is a somewhat deeper implications of Smolins ideas, that does not end with historical curiosity of human science. He has in several places and books elaborated on this and what it has to say about the notion of physical law. For example he notes that inferrable state spaces, are bound to be dynamical and the idea of timeless state spaces and laws are problematic if you insist on the abstractions to be inferred from real interactions. His CNS is one realisation of this, but the general idea behind is reasoning does not end where his specific CNS might.

This is the perspective I think makes most of his books worth the most.

The other stuff about personal things, politics is also interesting and entertaining but it's not the strongest points of the books.

/Fredrik

 

[QuantumKitty]

It seems this thread has turned into a book discussion ;-)

I agree with Fra and Naty1 about Smolin's book. I think he tries to encourage readers to think for themselves and not just agree with everything without at least knowing why they're agreeing. I also like the point Smolin makes about, as Fra put it, not putting all your eggs in one basket.I tried to read Randall's book Warped Passages. I made it through about 4 chapters before putting it down. One of these days I'll get around to finishing it.

 

[humanino]

Is Randall's book difficult or unpleasant ? I'm surprised, I found it excellent.

 

[QuantumKitty]

Is Randall's book difficult or unpleasant ? I'm surprised, I found it excellent.

It just didn't hold my attention and keep me interested. So I guess in a sense I found it difficult and it felt less like a hobby than a task to read it. Then again, maybe I was just being lazy...

 

[seerongo]

I haven't read Randall's book yet, but it may be worth noting that Amazon shows 152 customer reviews and averages 4.5 stars (out of 5). Coincidentally, one of the reviews was from Lee Smolin himself who gave the book 5 stars and said why he liked it. There were several other reviews by professionals in the field, although I only read maybe 10 of the reviews. BTW, one reviewer thought the second half was better than the first, but that was just one person.

So, even if some may find it a difficult read, it may be worth slogging through it anyway. I should be getting my copy from the library in a few days but I can't guarantee how long it will take me to get through it. I need to finish Greene's book first also.

Ron

 

[Fra]

Is Randall's book difficult or unpleasant ? I'm surprised, I found it excellent.

I haven't read this book and I don't even know what book it is, but all the talke made the curious. What book of hers are we talking about?

Can someone briefly describe the books main topics and points? Is it constrained to string theory or does it review other ideas as well?

/Fredrik

 

[seerongo]

Fra, Lisa Randall's book is called "Warped Passages" and is supposed to be a pretty comprehensive review of cutting edge physics leading mostly toward string theory. I'm hoping that she is a good writer and can get into the extra dimension business and Calabi-Yau spaces which seems to be at the heart of string theory. There is a quite a bit of info on it on the web. It's been out since about 2005.

Ron