Introduction: The world of Strings

String theory is a model of fundemental physics where the fundemental building blocks are not pont like particles but one dimensional objects called strings.

String theory tries to explain the fundamental laws of nature in an entirely different way. It includes one dimensional string like objects which does not exist in usual 4-dimensions (3-space and 1-time) but in ten, eleven or even twenty-six spatial dimensions.

The size of these particles are almost a plank length across, which is about 10^-35 meters. Just like the string of a violin, these elementary units called string can vibrate in a specific manner to give rise to different particles like quarks, baryons etc. which further give rise to neutrons and protons. The vibrations of a string are confined to only specific resonant frequencies. Further strings are of two types, a closed string (A) and an open string (B) as shown below.

Particle interactions:

So far we know that we do get our usual particles from the vibrations of the strings. But how and why do they interact with each other? For instance an electron and proton interact with each other with electrostatic force. How can we understand this with strings?

Well according to string theory, a string can split into two or even combine with another to from a new one. This splitting and recombining results in the production and absorption of particles and their interactions.