String Theory: Introduction

In the world of physics, there are always contests and divisions of thought, factions of people supporting different theories of why the universe is the way it is. Physics is divided into two different realms the macroscopic (large) world for things like gravity and then the quantum world (very small) where Quantum-chrono-dynamics (QCD) and Quantum gravity exist. With string theory, devised by Michael Duff, Michael Green and Brian Green et al, tried to unify these two worlds, the world of the macroscopic and quantum world to create a “theory of everything”, which works as a self sustained and self sustained mathematical model, which can allow for the description of the 12 fundamental forces and the different forms of matter.

String theory when first devised, was lead with some severe controversy. Scientists would not touch the subject let alone research it, due to the major consensus boycotting the research. People’s jobs and careers were on the line, chancing such an endeavor. But in the last 10 years, Sting theory has taken a big turn, making the topic much more serious and for respected academics to start brain storming about it.

 Fig.1 A Graphical representation of a vibrating string

In the Universe scientists have discovered that it is made up of two groups or very small important (Fundamental) particles, these are called the boson and fermions. With bosons, that are carriers of the fundamental forces, pertaining to, Strong/Weak nuclear forces, E.M Forces (Electromagnetic) and Gravity(the weaker of the 4 forces).  With fermions they are actually the matter that you can see such as atoms, molecules in all its configurations.

The standard model, which has been herald as the most stable and accurate scientific theory thought of, allowing for the explanation of the forces except for the force of gravity. As mentioned in previous post the inside of a black hole the mathematics breaks down in the singularity. This is simply because the standard model cannot explain the math and physics behind the mechanics of a singularities from a gravitational point of view. This also applied to the big bang theory as well.

A word that some people might of heard from time to time, and probably left them confused is the word super symmetry, this an important part of string theory. This is need for the string theory to actually work, where the concept that matter (particles) have a corresponding force.

More of will be covered in the next post. As this will a multiple post topic

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What is Gravity and why does it work?

Since Issac Newton, scientists have tried to grasp one of the 4 fundamental forces of nature. Gravity. The weaker of the 4 forces but yet little is known about the way it operates. We understand how it has a relationship with mass/matter and that gravity due to relativity can alter or bend space and time if strong enough. Examples of this would be black holes. Infinitely massive particles but reduced to an infinitely small space. Such compression typically makes a black hole. Though as mentioned in my previous posts black holes are not portals to another world or plane of existence. But what is inside them, is a tiny dot with so much mass, and light is unable to escape the clutches of the void.

So what is gravity, in its purest sense? How does it work? Well there are two answers to this question:

1) Nobody knows. It just does.

2) There's a very peculiar property of gravity that people have noticed for a long time. In particular, "gravitational charge" is exactly the same quantity as "inertial mass". That is, the "m" in the formula "F = G m1 m2 / r2" for gravitational attraction is exactly the same stuff as in the formula "F = ma". That is interesting, because there's no particular reason why that should be the case. But, for everything we've been able to measure (to exquisite accuracy) the "m" in the first formula is exactly the same as the "m" in the second formula, so that everything accelerates the same in the same gravitational field.

Well, forces with that property are often called "pseudo forces" and when they are observed they're usually just symptoms that you chose the wrong coordinate system to consider your problem. "Centrifugal force" is an example of a force like that -- if you're inside a sealed centrifuge, you can immediately tell that you are, even if you can't see out, because you stick to the walls. But someone in a near-inertial frame sitting around the outside of the centrifuge can see that the walls of the centrifuge are really just pulling you inward with an acceleration a, and f_centrifugal = m_you * a_centrifuge. (f=ma).

 Fig.1 Matter interacting with Gravity, and is influencing the space time fabric

Credit: PhysicsForum.com

The cool thing about Einstein's general theory of relativity is that it does away with the coincidence between the two kinds of mass. He instead explained gravity as a curvature of space time itself so that the straightest possible path through space and time curves slightly in the vicinity of mass. To do that, he had to produce a unified theory of space and time, which has us living in a four-dimensional place called "space time". The time axis is special in some ways but just like the spatial axes in other ways, for many things, you can treat time as "just" a different direction than the three we're used to.

The curvature is usually very, very slight, one of the important things to realize about Einsteinian relativity is that everything in the Universe is zipping along the "time" axis at the speed of light -- so if it takes you one second to jump up 4 feet from the ground and fall back down onto it, the amount of curvature of your trajectory is spread out over a complete light-second of motion (30,000 kilometres along your time axis). But because we don't perceive motion on the time axis directly, that curvature is very, very foreshortened and your trajectory looks like a tight parabola, just like you can spot a very slight bend in a pool cue by sighting down the length of the cue to foreshorten the cue itself.

 

Fig.2 Matter getting sucked in by a sheer gravitational vortices

Now, why does mass bend space time? Nobody knows. There are some very good ideas floating around, but the only solid answer right now is that nobody has been able to figure out why it actually happens. Though the unification of Quantum gravity is the makeup of General Relativity and Quantum Mechanics, which recently has taken a hit in the world of theoretical physics from analysed Gamma Ray Bursts. But in principle, no one theory has been proposed and has been proven, leading to an ever changing battle for the Grand Unified Theory.

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