Supergravity

Supergravity is a theory of gravity that includes supersymmetry in its equations. The theory of supergravity arose from the problem of incorporating the uncertainty principle with general relativity. When the equations of these two theories were combined a number of infinities appeared in the solutions. These infinities were troublesome to physicists. It was apparent to them that something was missing.

All particles exhibit a property known as spin. There is no definite definition of spin. Although physicists do not have a deep understanding of what spin is they do have a mathematical description of how it behaves. This allows them to compare spin's behavior to the behavior of other things that they feel that they understand better. Fermions have half-integer spin and their ground state energies (lowest energy level) are negative. Bosons have integer spin and their ground state energies are positive. The infinities resulting in combining the uncertainty principle with general relativity are the result of having an unequal number of fermions to bosons. When the supersymmetric particles suggested by supersymmetry are added to the equations the number of fermions is exactly equal to the number of bosons. The negative ground state energies of the fermions cancel out the positive ground state energies of the bosons eliminating the infinities. By eliminating these infinities the equations make more sense to physicists.

The equations of supergravity, as well as the equations of string theory, work best if you consider the universe to contain 11 dimensions. That is 10 dimensions of space and one dimension of time. When any other number of dimensions is considered the equations become unstable and produce anomalies. Some physicists believe that the reason that gravity is so weak compared to the other forces is because it is spread out among the other dimensions. The reason that we do not see the other dimensions is that they are too small to be seen.

Availability of Information

The availability of information provided by the Internet is astounding. It has truly changed the world and how we perceive it. Someone once said that knowledge is power, but I can’t remember who. Well, I’ll just plug that phrase into google. Voilà! Sir Francis Bacon said it. The information on the Internet is the culmination of our collective knowledge. The Internet allows every one of us access to that power. Whether we’re catching up on current events, doing some online shopping, or doing some research for work or school the Internet gives us access to the information that we desire at our fingertips anytime and, with the proliferation of mobile devices, anywhere.
 
The availability of information through the Internet has affected many industries. The retail industry has been profoundly affected. Retail stores can promote themselves online by advertising sales and discounts. Customers can look at the websites of different stores to compare prices and read reviews by other customers on the products that they wish to purchase. In the education industry the Internet has almost done away with the need to have actual books made from paper. Many books are available in electronic format. We can purchase a book online and download it to our computers or mobile devices. A lot of the information on the Internet that can be used by teachers is free. The Internet can be a great teaching tool if used carefully. A lot of information on the Internet is invalid and unverified. It is up to the user to judge whether the information is correct or not. When I want to learn something about a particular topic I will usually visit many websites that feature that topic and then try to sort out what is true and what is nonsense.

Cascading Style Sheets

I have done some work with HTML in the past and was recently introduced to cascading style sheets or CSS. I was amazed at how easy CSS make it to format web pages. All of the formatting for an entire web page can be done in small area of the HTML document. Once the document is completed and you don’t like how it looks you can make the formatting changes in the style section in the head of the document without having to navigate throughout the whole document to make the changes. You can make changes to the background, font, color, and alignment to the body of the web page. You can also create classes to control the formatting between particular HTML tags. It saves a lot of time particularly if you have a very large document that you want to format. I haven’t done any HTML programming in a long time, but now that I have some new tools my interest has been piqued. I’ve started looking at some of the old web pages that I created way back when and was wondering how I can improve them with CSS. Who knows, I may even upload them onto my Verizon web space again. It’s been so long since I’ve done anything with my web space that I cannot even remember the URL. I can’t even remember if I have a web page loaded or not. I’ll just add that to my list of things to do after I finish all of my homework.

Quantum Mechanics

Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics that attempts to describe the universe on an extremely small scale. Quantum field theory describes elementary particles as having a wave-particle duality. This duality states that elementary particles exhibit both the properties of waves and the properties of particles. Particles can be described as objects that have physical properties such as mass and momentum. Waves are how energy moves through a medium and have properties such as wavelength and frequency. Quantum field theory deals in probabilities as opposed to general relativity in which the result of experiments can be precisely predicted. In quantum field theory the result of an experiment cannot be precisely determined because the act of observing the particles in the experiment changes the result of the experiment. Physicist can only predict the probable outcome of an experiment. This is the basis of Heisenberg’s uncertainty principle which states that you cannot know at any point in time the exact position and velocity of a particle. The more you know about the position of a particle the less you can know about its velocity and vice versa. Einstein was deeply troubled by the uncertainty principle and the probabilities of quantum field theory. This prompted Einstein to say that “God does not play dice.” In the last years of his life he tried to disprove quantum field theory, but failed to do so.

The Standard Model

The standard model is a theory of particle physics that explains the relationship between the elementary particles of matter and the electromagnetic, weak nuclear, and strong nuclear forces. It basically describes what everything in the universe is made of and what keeps it all together. The standard model separates the elementary particles into groups. One group consists of fermions. Fermions are the elementary particles that form matter. The fermions group can be further broken down into quarks and leptons. The basic difference between quarks and leptons is that quarks are always found together forming other particles such as protons and neutrons. Leptons are solitary and do not join together to form other particles. The best known lepton is the electron which surrounds protons and neutrons to form atoms. Another group of elementary particles described in the standard model are the bosons. Bosons are particles that carry the fundamental forces of nature. For example a gluon is a boson that carries the strong nuclear force that holds the nucleus of atoms together. The strong force is propagated by particles exchanging gluons with each other. The other forces of nature are propagated in the same way with particles exchanging bosons with each other. The force of gravity is propagated by a boson called the graviton. The graviton has not been found yet, but physicist can predict its existence through experimentation. String theory suggests that all of the particles in the standard model are vibrating strings and not point particles. String theory also suggests that the standard model is not complete. According to string theory each of the particles in the standard model has a supersymmetric partner particle. These supersymmetric partner particles are predicted to exist by string theory, but have not yet been proven to exist by experimentation.

General Relativity

General relativity is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915. Before general relativity Newton’s law of universal gravitation had been the accepted explanation of the gravitational forces between masses. According to general relativity the observed gravitational attraction between masses results from their warping of space and time. Through observations and experiments the general theory of relativity accounts for several effects of gravity that are unexplained by Newton’s laws. General relativity predicts effects of gravity such as gravitational waves, gravitational lensing, and the effect of gravity on time known as gravitational time dilation. Many of these predictions have been confirmed by experimentation while others are the subject of ongoing research. General relativity deals with physics on the large scale. At the very small scales of quantum mechanics the mathematical models of general relativity produce inconsistent results. The mathematical models of string theory reconcile most of the inconsistencies produced when combining general relativity with quantum mechanics. 

String Theory In a Nutshell

String theory postulates that the quarks and electrons that make up an atom are made up of 1- dimensional vibrating strings. The frequency of the vibrations determines what type of particle each string makes. The theory has been around for more than 30 years and was developed to reconcile some of the inconsistencies in our current knowledge of particle physics.

In order to understand the basics of string theory one needs to understand the other theories that string theory was developed to work with. General Relativity, The Standard Model, and Quantum Mechanics have all played major roles in the development of string theory.

The first developed string theory is the Bosonic String theory. A major problem with this theory is that it only includes force carrying particles called bosons while many particles are fermions which are the particles that make up matter. With the introduction of supersymmetry 5 new string theories emerged that include bosons and fermions. These new string theories are called superstring theories. At first physicists believed that only 1 of the 5 theories was the correct theory. After years of research physicist now believe that all 5 theories are correct and each one is just a different aspect of the same theory. M-theory was developed to combine the 5 superstring theories into a model where they complement each other.

Proponents of string theory suggest that it is a good candidate for a theory of everything where all known physical phenomena are linked and the outcome of any experiment can be predicted. Opponents of string theory argue that many of the theories aspects cannot be proven with experimentation at our current level of technology.