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From: mohammad zaman <meghobristi@y...>
Date: Fri Apr 16, 2004 8:06 am
Subject: Re: [banglarnari] Bangla Article on String theory

Dear Avijit,

Great Job!

About a month ago I asked Aparthib Bhai to write something on String Theory for commoners. It is fascinating.

As per Aparhib Bhai's advice I read the Elegent Universe, Brian Greene's prologue to his recent Fabic of the Cosmos. I am almost half way in this book ...

This is more than a thriller - simply exhilariting even for a non-physicist like me!!

Zaman

From: Aparthib <aparthib@f...>
Date: Sat Apr 17, 2004 5:46 am
Subject: Re: Re: Bangla Article on String theory

Indeed, its great that Avijit took the time and effort to present this fascinating idea of modern physics to layfolks.

Here is the "official" site for String theory, which contains a basic intro to string ideas, people engaged in string research, history of strings etc :

http://www.superstringtheory.com/index.html

Quite interestingly, the leading string theorists represent a mix of ethnicity and gender. Eva Silverstein, whose name was mentioned in my article on International Women's day in Banglarnari is also listed in that site under people. Some leading string theorists not mentioned in that site are Harvard string theorist Cumran Vafa (Iranian origin), Ashoke Sen of Mehta Research Institute, Allahabad, Lisa Randall at Harvard (who has worked with Raman Sunduram on many string papers). Below is the link to an interview of Lisa Randall on strings, branes...

http://www.esi-topics.com/brane/interviews/DrLisaRandall.html

One can see how metaphysical and esoteric the notion of string theory is by simply reading this interview. But its NOT VAGUE metaphysics like all other metaphysics. Another source for a popular intro to strings would be Stephen Hawking's latest book "Universe in a nutshell". Hawking has lately turned his attention to strings having been preoccupied with the large scale structure of spacetime for over thirty years. To me the the most intriguing question is how humans could even conceive of extra hidden dimensions. Evolutionary explanations exist for most human traits like love, aggression, aesthetics sense etc. But there is no evolutionary explanation yet of why human brain could conceive and comprehend the existence of compactified extra dimensions, or put simply, how "brains" could conceive of "branes" is a mystery. Brain and brane will be the hottest are of research in the 21st century. Maybe understanding brane may help understand "brains" or vice versa in an intriguing closed consistency loop. :)

Subject:	String Theory
Date:	Sat, 17 Apr 2004 18:44:37 +0800
From:	"Tanveer Saleh" <[email protected]>
To:	[email protected]

Dear Mr. Avijit,

I have read one article of yours regarding the String theory. I am not a student of Physics but i have a lot of interest in physics. I have two question about the string theory, if you know the answer please clarify my queries.

1. What is this string is made from? We know everything is either matter or energy. The particles like photons are actually energy but travels in packet like particle form, please let me know if i am wrong. Then what is this string?

2. If this string is compared with the violin string then it has to be fixed in some point/points if he wants to oscillate, right? is it So means is it fixed somewhere, then where? i will be glad if you do drop some line, even if my questions are childish.

Thank You Tanveer.

From: "Avijit Roy"
Date: Sat Apr 17, 2004 1:48 pm
Subject: Re: String Theory

Dear Mr. Saleh,

Greetings. and thax for writing me directly for your enquiries. I will try to answer from my limited knowledge in the subject.

Answer: The fundamental particles of the universe that physicists have identified -- electrons, neutrinos, quarks, and so on -- are the main constituents of all matter. According to string theory, if we could examine these particles with even greater precision -- a precision many orders of magnitude beyond our present technological capacity -- we would find that each is not point-like but instead consists of a tiny, one-dimensional loop. Like an infinitely thin rubber band, each particle contains a vibrating, oscillating, dancing filament that physicists have named a string.

From E= mc^2, we know that mass and energy are interchangeable, just like Bangladeshi taka and Singaporean dollar. We see from everyday life that energy is produced from mass. But you might not know, Einstein's theory also works perfectly in reverse; i.e mass can be produced from energy. The mass of a particle in a string theory is nothing but the energy of the vibrating string. Infarct, this phenomenon of string theory explains why one particle is heavier than other is just because, the string constituting heavier particle is vibrating faster and rapidly than the string constituting lighter particle.

You are correct about photon. it is a "bundle" of light and messenger particle of electromagnetic force. Difference b/n photon and string is that photon produced from string vibration, of course the vibration pattern will be most placid and gentle as possible because of it's light mass (in fact mass less). So strings are more finer constituents in the entire scenario. So those Strings are fundamental one-dimensional object that is the essential ingredient in string theory.

2. If this string is compared with the violin string then it has to be fixed in some point/points if he wants to oscillate, right? is it So means is it fixed somewhere, then where?

Answer: Guitar or violin were just some analogies to make complex matter clear to the general readers. No, fundamentally strings do not need to be fixed in certain point (they may be open or closed). Just consider molecular vibration in a matter or any other self exciting system. They do not need to be stick to any fixed boundary or point. Strings on a violin or on a piano are normally used to make analogy for the general readers to give the view of resonant frequencies at which the strings prefer to vibrate. But rather than producing musical notes, each of the preferred mass and force charges are determined by the string's oscillatory pattern in String theory.

Hope I could answer your questions properly. I am giving a CC to mukto-mona forum, so that our readers can also be benefited, and of course they can also point out if I stated something wrongly.

take care.

avijit

From: Raman Shah
Date: Sat Apr 17, 2004 7:01 pm
Subject: Re: [mukto-mona] Re: String Theory

Any particle that has a finite "mass" is considered "matter" (e.g., protons, electrons, neutrons...). Photons are energy (wave) or energy (wave) packets. As of now there it is not known whether strings have either finite mass or have a upper limit on its mass. Regards, Raman Shah

Date:	Fri, 16 Apr 2004 20:26:21 -0600
From:	"Sohel" <[email protected]>
Subject:	Re: Bangla Article on String theory
To:	"Avijit Roy" <[email protected]>

http://groups.yahoo.com/group/MuktoChinta/message/10411 

Dear Avijit,

An excellent article, enjoyed reading it. Hope to see more of your
thoughtful articles.

I'm also reading a few books on this subject, this is indeed a 
fascinating
subject.

Best Wishes,
Sohel

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