Transcript File

String Theory Talk
Agenda
 Science in the news
 String Theory Talk!
 Higgs Boson Discussion (brief)
Introduction
 4 fundamental forces of nature
 Weak Nuclear Force: Quantum Flavordynamis
 Strong Nuclear Force: Quantum Chromodynamics
 Gravity
 Electromagnetism: Quantum Electrodynamics
Weak Interaction
 Affect all fermions (half spin particles)
 Theorized to be caused by exchange of W and Z
bosons.

The heaviness of these bosons account for the small range of
the weak interaction.
Strong Interaction
 Strongest force, shortest range.
 Holds together protons and neutrons.
 Held together by gluons.
 Caused by meson exchange.
 Helps overcome electrostatic repulsion.
 Relationship between quarks and gluons is known as
quantum chromodynamics.


Pecei Quinn Theory
Yangsmill Equations
Gravity
 Theorized to be caused by the exchange of gravitons.
 Defined by the universal law of gravitation:
Electromagnetism
 Magnetic Field:
 Caused by a charge in motion
 Electric field:
 Caused by presence of an electric charge
Strong in short distances.
Elementary Particles
 You cannot break it down any further.
 Even protons and neutrons can be broken down.
 Three main types:
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Quarks:






Leptons:



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Fundamental constituent of matter.
Combine to form large particles called hadrons.
They can’t be found in isolation.
Various properties.
Six types known as flavors.
Does not undergo strong interactions but is subject to the pauli exclusion principle.
Electron is a lepton.
Two types:
 Electron-like (charged)
 Neutrally charged (neutrinos)
Exchange Particles:


Higgs, mesons, gravitons, etc.
Govern the four forces.
Pauli Exclusion Principle
 Particles with the same quantum state cannot occupy
the same place.
String Theory
 Why is it called the Theory of Everything? Because it
is the one theory that can tie together all four
fundamental forces of nature.
 It can bridge the gap between Relativity and
Newtonian Mechanics.

It can explain how light behaves both as a wave and a particle.
(quantum-photoelectric effect)
String Theory
(or the Theory of Everything)
By Alex Smith
The Basics of String Theory
 Why is it called String Theory?
 Where did String Theory come from, and where is it
now?
 What are some of the requirements of String Theory?
 What does String Theory solve?
 Do we have any proof?
What are the “strings” of
String Theory?
 Miniscule vibrating strands of energy of energy.
 Fundamental unit of the universe. Different ways of
vibrating yield different particles.
 MUCH smaller than any particle.
The
parts
of
String
 The Standard Model
Theory
Describes all known particles. Now complete with
the discovery of the


Higgs Boson.
However, fails to explain gravity or the existence of Dark matter.
 Quantum Mechanics

Describes the three strong fundamental forces in the universe:
Electromagnetism, Strong Nuclear Force, and the Weak Nuclear
Force.
 General Relativity

The explanation of Gravity, the weakest fundamental force.
String Theory Combines these three to create an
all-encompassing picture of reality
Odds and Ends of String Theory
 It requires multiple Dimensions.
 Requires 10 spatial dimensions and one dimension of time.
 These can be either curled up at every point in space, or the
multiverse can be of a higher dimension and we are living in a
3-D membrane, where the strings are attached
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
String theory needs there to be supersymmetry with the particles to
work.
Every particle has a supersymetric partner that is much heavier.
The purpose of String Theory
 Solves Quantum Gravity
 It explains why gravity is so weak: it escapes off of our
membrane and into the higher-dimensional multiverse.
 Unites the Fundamental Forces
 All fundamental forces are united into a single theory to
describe everything. The Holy Grail for scientists.
One Small Problem
 There is currently no proof for string theory, despite
the several decades of it’s existence
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
The theory provides no observable predictions. You can’t claim it as
truth if there is nothing to prove.
So far, supersymmetry is yet undiscovered, but this would not prove
String Theory, or the existence of the Graviton.
The Fuzzball
THE STRING THEORY
VERSION OF A BLACK HOLE
BY MAX FONTANA
Definition
 A Fuzzball is, in superstring theory, the true
quantum description of a black hole
 This theory helps solve two fundamental problems in
the modern definition of a black hole
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The Information Paradox
The singularity at the heart of the black hole
 Idea was conceived by Samir Mathur of Ohio State
University and postdoctoral researcher Oleg Lunin in
2002
Event Horizon
 The physical surface
 Space-time is distorted
around the event horizon
 Light bends around it
 The escape velocity is
equal to the speed of light
 Known as “The Point of
No Return” because it is
impossible for anything to
escape the black hole past
this point
Information Paradox
 The quantum mechanical law of reversibility states that
quantum information cannot be lost in any process
 A black hole’s singularity has no composition, meaning
that the composition of quantum information would be
lost
 The information paradox states that all quantum
information of matter and energy that falls into a black
hole would entirely vanish due to the zero-volume
singularity at the heart of the black hole
 The Fuzzball theory corrects this by suggesting that the
strings that fall into the fuzzball contribute to its makeup,
thus no quantum information is lost
Singularity at the Heart
 In the classic definition of a black hole, the heart is a
region of gravitational singularity, where space-time
curvature becomes
infinite due to
the infinitely
intense gravitational field
in
a zero volume region
 The Fuzzball Theory proposes that the entire area
within the event horizon is a ball of strings
 Therefore, there would be no infinite gravitational
energy in a zero volume area
space-time curve, becomes infinite in a black
hole
Physical Properties
 Whereas a black hole is described as having a distinct
event horizon, a fuzzball would be like a mist

This “mist” is only about a few Planck lengths long
 Small fuzzballs are theorized to form from extremely
dense neutron stars, where the neutrons will have
“melted” down to the quarks, which are strings in string
theory
 A fuzzball is a black hole, and space-time, light, and
anything that gets near its event horizon acts similarly
 Fuzzballs and black holes are unrelated only at the
quantum level
Physical Properties
 The volume of a fuzzball is a function of the
Schwarzschild radius, which is equivalent to about
3,000 meters per solar mass
 The density of a fuzzball decreases as the inverse
square of their mass


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(Mass*2) = (Diameter*2) = (Volume*8 ) = (Density/4)
A typical 6.8 solar-mass fuzzball would have a mean density of 4.0×1017 kg/m3
A piece of such a fuzzball the size of a drop of water would weigh about 20,000,000
metric tons on Earth
 Fuzzballs become less dense as their mass
increases because of fractional tension.
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When matter or energy fall into a fuzzball, strings fuse together instead of being added to
the amount of strings already in the fuzzball
Thus, the quantum information from the strings falling into the fuzzball become part of
larger, more complex strings, resolving the information paradox
Sources
 Mathur, Samir D. "The Fuzzball Proposal for Black
Holes: An Elementary Review." Cornell University
Library, 3 Feb. 2005. Web.
 CERN. "The Black Hole Information Problem and
the Fuzzball Proposal I." CERN, Geneva, 11 Feb.
2009. Web.
 CERN. "The Black Hole Information Problem and
the Fuzzball Proposal III." CERN, Geneva, 12 Feb.
2009. Web.
Thank you for coming!
 Other presentations will be uploaded shortly.