string theory: the theory of everything

8/14/2019 String Theory: The Theory of Everything

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not work instantly; instead it takes time for the gravitational pull the Sun has on the Earth

to reach us. He supports this claim with showing that there is a cosmic speed limit. It

is said the cosmic speed limit is that of the speed of light, nothing is able to overcome this

(NOVA). Since Einstein claims that nothing is able to surpass this, gravity then in turn

takes the same time to reach earth. A revised visual in The Elegant Universe shows what

would happen if the sun was to disappear following Einsteins theory. When the Sun

disappears, the Earth would stay in orbit and will continue to have light and gravity. This

is because Einstein also says that the speed of gravity travels in ripples across space at the

speed of light (NOVA). As the last of the light from the Sun reaches Earth, so does its

gravitational pull. When the last of the both of these pass the Earth, it would be then that

we veer off our orbit and wander into space. Einstein gave the name to his theory

General Relativity (NOVA). It was after this that Einstein then wanted to come up with a

theory that could explain everything. Einstein's goal was to be able to combine the

theory of gravity and electromagnetism. Electromagnetism is the combination of

electricity and magnetism. A man named James Clark Maxwell brought the relationship

between the two together. Although Albert Einstein spent most of his life trying to create

a universal theory, he ran out of time when he died.

It was in the 1930s that a new type of physics was introduced. The name of this

one is Quantum Mechanics. Quantum mechanics created a problem with general

relativity. In general relativity, it states that everything in the universe can be predicted

with equations (NOVA). With quantum mechanics, it is said that this is not true; that the

best we can do is predict the chances of one outcome of another. Although many

contradictory claims were made in quantum mechanics, many new ones were made as


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well. One of these new claims is that parallel universes exist. Although there were many

good points made with quantum mechanics it lacked in explaining one very important

thing, gravity. Both general relativity and quantum mechanics make the claim that they

(the theories) exist everywhere (NOVA). The problem that arises is that we are unable to

have two everywheres. A reason to unite these two theories, or to completely prove

one another wrong never really existed until the discovery of black holes was found.

Black holes asked a question that made people think, which was do you use general

relativity because the star is incredibly heavy or quantum mechanics because it's

incredibly tiny, (NOVA). An answer to this question was not one or another of the two,

but it was both combined, creating something completely new.

It was here that quantum gravity was found. Quantum gravity is a theory that

successfully merges quantum mechanics and general relativity. Quantum gravity is also

the backbone to string theory. It was in 1968 that the first indication of string theory

emerged (Gribbin 154n). Two men, Gabriel Veneziano and Mahiko Suzuki, who were

researchers at CERN, came across a mathematical formula used in the 19th century by

Leonhard Euler (Gribbin 154n). It was with this formula that the two researchers were

able to describe the behavior of strongly interacting particles. These mathematical

formulas were then later taken by Yoichuro Nambu at The University of Chicago and

turned into physics (Gribbin 154n). It was then later in 1974 that Jol Sherk and John

Schwarz published a paper that showed how string theory is able to describe gravitational

force. As John Schwarz says, We felt strongly that string theory was too beautiful a

mathematical structure to be completely irrelevant to nature. Although this is was a

break through, but it was never really noticed; the popularity of string theory was dying


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off. Ten years later, string theory became popular again. The reason for this was because

the new theory that was proposed, quantum chromodynamics (John H. Schwarz) was

getting nowhere and John Schwarz and Mike Green came published another paper. This

paper showed how string theory was able to explain the existence of particles with built-

in left-handedness.

Before any more is said about string theory, it is important to state what it is.

String theory is the theory that describes particles in terms of strings (Lidsey 51). It is

these strings that make up everything in our universe. From You and I to the stars, they

are all made up of strings. A string is defined as energy as a string vibrating at different

frequencies (NOVA and Lidsey 52). It is with these different vibrations that give each

string its identity. There are two different types of strings, open and closed (these will

be talked about into further detail later). These strings have elastic like properties

(Lidsey 52). The open strings are tied down to our membrane, or universal fabric. The

closed strings are not tied down to these membranes (NOVA). Strings have on property

that is shared in every string. Each string is one dimensional (Glossary), the dimension

of length.

String theorys popularity was beginning to die off. But before string theory

began to die off in the early 1970s, a few different types of string theories were already

devised. These are known as Type I theory and Type II theory (Gribbin 170). Although

Type I and Type II had many differences, there was one major difference. This was that

Type I consists of open strings while Type II consists of closed strings (Gribbin 167-171).

An open string is a string that is attached to the fabric of space and our universe. Type

II has closed string, which are not attached to this fabric (Gribbin 167-171). The most


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common type of closed string is a graviton. A graviton is the smallest bundle of the

gravitational force field (Susskind 387). The special thing about a graviton and other

type of closed strings (such as photons) is that they are not attached to the fabric

(NOVA). Since they are not attached, they then become massless (John H. Schwarz) and

then are able to float around freely. Since they can float around freely, this means (in

theory) that other parallel universes can feel them. The easiest way to explain a

parallel universe is through a visual. InFigure 1-1 (I still have yet to find a picture

online, so I am thinking I will just photocopy a picture from one of my books), it is

shown that it is possible for multiple universes to co-exist. One question that is always

brought up is; why cant we see it (it being the other universes). The answer to this

question is fairly simple. When going back to Type I, it is explained that a string is

attached to the fabric of our universe. We (people) are also composed of these open

strings, and then are bound to our fabric. Each universe has its own fabric. Since we

(our open strings) are bound to our fabric, that means that it would be impossible to see

anything on another fabric, even if it is less than an inch away. This is where Type II

comes into play. Since in Type II, the closed strings are NOT bound to our fabric, they

are able to float around freely. As this is explained in The Elegant Universe, gravitons

are able to travel from one universe to another. This is because they are not bound to the

fabric, unlike open string. At this time, these two theories, along with another one

called the heterotic theory, were battling among each other to be the correct version of

string theory. This went on for some time until a revolutionary proposal was made to end

this.


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In 1995, Edward Witten, a theoretical physicist, made a proposal that got rid of

these many different theories. His proposal was called the M-Theory. Witten claimed

that these different theories were not different, they were in fact the same, and they were

just being looked at in different ways. M-Theory is the theory that he came up with; it

was a combination of Type I, Type II and the Heterotic. Along with the combination of

these theories, there was also the proposal of there being eleven dimensions. A

dimension is, an independent axis or direction in space or spacetime (Glossary). What

was (and still is) accepted is that there are only the four dimensions, the three space and

the one time.

M-Theory is accepted by many notable physicists, but not everyone agrees with it.

Stephen Hawking, in his book, The Theory of Everything, he explains the reasons that are

given from string theory critics to attempt to prove how it does not exist (Hawkings 159).

Hawking once again brings up the point that we cannot see these other universes, so they

must not exist. Another reason is that of the extra dimensions (Hawking 158). Hawking

explains how if these other dimensions did exist, it would not be possible for life, as we

know it to exist, even in other universes (Hawking 159). An opposing argument is that it

is unreasonable to make this claim. Since we are never going to be even to look into

another universe. We can only make assumption, and who is to say that the same laws of

physics that exist in our universe exist in others as well. The same is to be said about

string theory. James E. Lidsey makes this very clear in his bookThe Bigger Bang, This

picture of particles as strings is very appealing. We should emphasize, however, that the

superstring concept is just a theory at this stage. (Lidsey 52). Hawking then someone


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restates this in his book as well, but with a bit more support. Hawking makes three

suggestions about a unified theory of everything. They are

- There really is a complete unified theory, which we will someday

discover is we are smart enough- There is no ultimate theory of the universe, just an infinite sequence

of theories that describe the universe more and more accurately

- There is no theory of the universe. Events cannot be predicted beyonda certain extent but occur in a random and arbitrary manner. (Hawking 160)


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Works Cited

"Glossary". NOVA. February 26, 2009

.

Gribbin, John. The Search for Superstrings, Symmetry, and the Theory of Everything.

Boston: Little, Brown, 1998.

Hawking, Stephen. The Theory of Everything. City: New Millennium Press, 2002.

Lidsey, James. The Bigger Bang. Cambridge: Cambridge University Press, 2000.

NOVA - The Elegant Universe. Dir. Joseph Mcmaster. Perf. Michael B. Green, Joseph

Lykken, Maria Spiropulu. DVD. Wgbh Boston, 2004.

Schwarz, John. "John H. Schwarz". February 26, 2009

.

Susskind, Leonard. The Cosmic Landscape. Boston: Little, Brown and Co, 2006.

string theory: the theory of everything

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