# Homework Help: Grand Unification Theory (GUT)

1. Dec 24, 2005

### hotp

Hey im new to the site...i have to write an essay on 'an unsolved problem in modern physics' ive started (i chose GUTs)
could sum1 check it over and if possible help me out cos im stuk! :(

An unsolved problem in modern physics:

The problem I will be discussing is that of the ‘Grand Unification Theory (GUT).’ A unified theory is one in which there is a mathematical backbone, where all forces and particles occur naturally (e.g. under a unified experiment no masses or charges would have to be fixed for the experiment to work). In physics the GUT is a means by which the fundamental forces would be united together (mathematically) as one ‘single unified force’.
The forces are:
1. Electrical
2. Magnetic
3. Weak Nuclear Force (WNF)
4. Strong Nuclear Force (SNF)
5. Gravity
The first unification breakthrough occurred in 1860 when James Maxwell joined the first two to form Electromagnetism(EM). In 1967 EM and the WNF were joined by Salam and Weinberg and the ‘Electroweak force (EWF)’ was devised (i.e. at high enough energies it was shown that both EM and WNF were aspects of the same force. It predicted the existence of W and Z bosons (these were later proved to exist via proton-antiproton collision experiments).
With the formation of the EWF this lead to the ‘Standard Model’ of three interactions: EM, WNF and the SNF. In this model, particles like muons, electrons, quarks and neutrinos make up matter. They interact through the mentioned forces. The force carriers are other particles, such as photons, gluons, W and Z bosons. The SM allows the prediction of rates of interactions between particles and can be confirmed through experimentation. Yet it does not include the most well known force of all: Gravity. Along with this is the fact that the SM requires ‘fine-tuning’ various constants to allow real world calculations such as the ‘constant of gravity’ and the ‘speed of light.’
Various attempts have been made at unifying both the SM and Gravity.
STILL GOT 700 WORDS 2 WRITE!!!!

2. Dec 24, 2005

### inha

The way you start is a bit off. Electrical and magnetic forces are of the same origin at the same energy scale unlike the EM and weak interaction for example.

As for increasing the length, you cover the force mediating particles and the constituents of matter with just a sentence when you could easily write paragraph after paragraph about those. Just expand on what you've written so far.

3. Dec 24, 2005

### rbj

i doubt this will help with your 700 words, but the value for $G$ and for $c$ is purely a human construct. the numbers depend solely on the system of units used to measure them. i doubt that the SM cares about what system of units you would use.