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Superstring Theory: The DNA of Reality

One of the most exciting scientific adventures of all time is the search for the ultimate nature of physical reality.

Overview

One of the most exciting scientific adventures of all time is the search for the ultimate nature of physical reality. The latest advance in this epic quest is string theory. Dr. S. James Gates, Jr., has presented more than 100 public talks on string theory, enhanced by a set of visual aids designed to convey to a lay audience the difficult mathematical ideas that underlie this subject. Are you eager to look over the shoulder of a prominent theorist at work-one who has a gift for explaining the subject to nonscientists? Prepare to be intrigued, enlightened, and amazed.

About

S. James Gates Jr.

Ultimately science is also an act of faith.

INSTITUTION

University of Maryland, College Park

Dr. S. James Gates Jr. is the John S. Toll Professor of Physics and Director of the Center for String and Particle Theory at the University of Maryland at College Park. He earned two B.S. degrees in mathematics and physics and earned his Ph.D. in the studies of elementary particle physics and quantum field theory at the Massachusetts Institute of Technology. Dr. Gates's first post was a Junior Fellow in the Harvard Society of Fellows. That led to an appointment at the California Institute of Technology and a faculty appointment at the Massachusetts Institute of Technology. During his tenure at the University of Maryland, Dr. Gates served a leave of absence as Professor of Physics and Department Chair at Howard University. Professor Gates is the recipient of many awards and honors, including the American Physical Society's Bouchet Award; the MIT Martin Luther King, Jr., Leadership Award; the Klopsteg Award of the American Association of Physics Teachers; the Washington Academy of Sciences College Science Teacher of the Year Award; and the 2006 Public Understanding of Science and Technology Award by the American Association for the Advancement of Science. In 2009, he was appointed to the President's Council of Advisers on Science and Technology and became a member of the Maryland State Board of Education. Professor Gates is the author or coauthor of more than 180 published research papers and is the coauthor of Superspace, or 1001 Lessons in Supersymmetry. Professor Gates has been featured on four PBS television series: Breakthrough: The Changing Face of Science in America; A Science Odyssey; The Elegant Universe; and E = mc2: The Biography of the World's Most Famous Equation. Professor Gates has also served as a consultant for the National Science Foundation, the U.S. Department of Energy, and the U.S. Department of Defense.

By This Professor

The Macro/Micro/Mathematical Connection

01: The Macro/Micro/Mathematical Connection

Professor Gates opens with a survey of the goals of the series and introduces the concept of strings, which are incredibly tiny objects that may be the most fundamental objects in the universe. String theory is not yet experimental physics; it is theoretical physics, based on sophisticated mathematical ideas.

34 min
Who Is Afraid of Music?

02: Who Is Afraid of Music?

Mathematics will play an important role in this course because string theory is purely mathematical. But instead of studying equations, you will explore the mathematics of strings through computer images and animations. These are comparable to the music generated by notes on a musical score.

31 min
Apropos Einstein's Perfect Brainstorm Year

03: Apropos Einstein's Perfect Brainstorm Year

This lecture explores Einstein's general theory of relativity, which led to a new understanding of gravity and sparked Einstein's quest for a "theory of everything." Building a mathematical theory of everything is like confronting a complicated toy on Christmas Eve, whose box states, "some assembly required."

31 min
Honey, I Shrunk to the Quantum World—Part I

04: Honey, I Shrunk to the Quantum World—Part I

In the first of two lectures on the quantum world, you start at the level of the atom and dig deeper, discovering the following: leptons (electronlike objects); nuclear matter (protons, neutrons); quarks (subnuclear matter); and force carriers (photons, gluons, W and Z bosons, and gravitons).

30 min
Honey, I Shrunk to the Quantum World—Part II

05: Honey, I Shrunk to the Quantum World—Part II

You investigate more properties of the quantum world, including spin, the Pauli exclusion principle, quantization, vacuum polarization, and quantum tunneling. You are also introduced to the Higgs boson, sometimes called the "God particle" for its apparent role in imparting mass to other particles.

31 min
Dr. Hawking's Dilemma

06: Dr. Hawking's Dilemma

Any object that possesses a temperature above absolute zero must give off thermal radiation. But how is this possible with a black hole, which is so massive that not even light can escape from it? In 1975, Stephen Hawking forced a crisis in theoretical physics with a stunning theory addressing this problem.

30 min
I'd Like to See a Cosmos Sing in Perfect Harmony

07: I'd Like to See a Cosmos Sing in Perfect Harmony

In trying to explain black holes in a way consistent with Hawking's 1975 theory, scientists had to combine two pillars of physics—quantum theory and the general theory relativity. The resulting mathematics predicted a surprising form of matter: strings.

30 min
Einstein's Hypotenuse and Strings—Part I

08: Einstein's Hypotenuse and Strings—Part I

String theory may involve extra dimensions beyond the familiar three of space plus one of time. But how are physicists able to think about extra dimensions? The Pythagorean theorem provides a model, showing that it's possible to calculate the properties of objects in higher dimensions without having to visualize them.

29 min
Einstein's Hypotenuse and Strings—Part II

09: Einstein's Hypotenuse and Strings—Part II

Einstein incorporated the fourth dimension of time into the Pythagorean theorem and came up with an idea known as the Einstein hypotenuse. This led to the famous equation E = mc2, which can be interpreted as a statement about areas in a four-dimensional world. You see how Einstein's hypotenuse led to an object that could have destroyed the world of physics: the tachyon.

30 min
Tying Up the Tachyon Monster with Spinning Strings

10: Tying Up the Tachyon Monster with Spinning Strings

This lecture explores the phenomenon of spin, which is ubiquitous in the quantum world. Spin was well known to particle physicists in the 1970s, but it presented problems for the first generation of string theory. A new generation of spinning strings solved the problem and also dealt with the tachyon threat.

32 min
The Invasion of the Anti-Commuting Numbers

11: The Invasion of the Anti-Commuting Numbers

Starting with the frustum (a truncated pyramid) on the back of a dollar bill, you explore some intriguing properties of numbers, including anti-commuting Grassman numbers. Anticommutivity is useful in quantum mechanics and manages to banish the tachyon from certain versions of string theory.

31 min
It's a Bird—A Plane—No, It's Superstring!

12: It's a Bird—A Plane—No, It's Superstring!

In 1977 three physicists—Gliozzi, Sherk, and Olive—observed that it is supersymmetry (the equality of bosons and fermions) that kills the tachyon monster. Supersymmetry is the child of string theory and the parent of superstrings. But why are there five versions of superstrings.

30 min
Gauge Theory—A Brief Return to the Real World

13: Gauge Theory—A Brief Return to the Real World

While working on supersymmetry around 1982, physicists Schwarz and Green found a solution that required 496 charges, implying a world in which there are 32 possible ways to rotate. The resulting string was called the SO(32) superstring, and was the world's first unified field theory, achieving a dream of Einstein.

30 min
Princeton String Quartet Concerti—Part I

14: Princeton String Quartet Concerti—Part I

Circular polarization of light possesses a mathematical property useful in superstring theory. Standing waves, left-moving waves, and right-moving waves are introduced in this lecture. Recognition that all three exist in superstring theory led to a new "heterotic" string constructed by a group of four physicists at Princeton in 1984.

30 min
Princeton String Quartet Concerti—Part II

15: Princeton String Quartet Concerti—Part II

The initial work of the "Princeton String Quartet" led to two strings from different dimensions: a left-moving superstring and the old bosonic right-moving string. But this work did not incorporate the requisite 496 charges. This lecture explores a new description of the heterotic string that produces that magic number.

29 min
Extra Dimensions—Ether-like or Quark-like?

16: Extra Dimensions—Ether-like or Quark-like?

It is often said that string theory requires extra dimensions, but that's not quite true. The mathematics of the heterotic string can be interpreted with extra dimensions or without. What appear to be extra dimensions can be understood as angular variables associated with the change of force-carrying particles.

31 min
The Fundamental Forces Strung Out

17: The Fundamental Forces Strung Out

This lecture shows how superstring theory provides mathematical support for Hawking's theory of black-hole radiation, which was discussed earlier in the course. Observational proof of string theory may come not by looking at nature's smallest structures but by looking at its largest: the universe itself.

30 min
Do-See-Do and Swing Your Superpartner—Part I

18: Do-See-Do and Swing Your Superpartner—Part I

Why does the universe observe a dichotomy, in which beams of matter obey the Pauli exclusion principle but beams of energy do not? The universe may be more symmetrical than this model suggests. Here, you look at evidence for supersymmetry that points to the existence of superpartners for ordinary matter.

30 min
Do-See-Do and Swing Your Superpartner—Part II

19: Do-See-Do and Swing Your Superpartner—Part II

Supersymmetry implies that every known matter particle has a superpartner that has yet to be observed in the laboratory. In fact, it is much more likely that superpartners will be discovered indirectly than in the lab. This lecture covers a technique for detecting them.

30 min
A Superpartner for Dr. Einstein's Graviton

20: A Superpartner for Dr. Einstein's Graviton

Can physicists find a consistent way to introduce mass to the superpartners so that they become very heavy while ordinary matter remains very light? The Higgs mechanism is one such method and may offer an explanation for the mysterious dark matter that is key to the formation of galaxies.

30 min
Can 4D Forces (without Gravity) Love Strings?

21: Can 4D Forces (without Gravity) Love Strings?

This lecture follows current attempts to use concepts from string theory to understand the forces and structures of matter inside the proton and neutron. You also visit the strange world of branes, and explore the type IIB string, which is one of five types of superstrings.

30 min
If You Knew SUSY

22: If You Knew SUSY

If you were to pick up a physics journal from the last 20 years, you would likely come across the word SUSY, which means supersymmetric. In this lecture, you study an unusual aspect of SUSY, superspace, and learn how it accounts for the five types of superstrings.

31 min
Can I Have that Extra Dimension in the Window?

23: Can I Have that Extra Dimension in the Window?

Strings supposedly describe everything. But if that's true, how can there be five different "everythings"? This lecture investigates a possible solution in 11-dimensional supergravity, which may be part of a larger and even more mysterious construct, M-theory.

30 min
Is String Theory the Theory of Our Universe?

24: Is String Theory the Theory of Our Universe?

String theory weaves together an amazing story with contributions by several generations of mathematicians and physicists. Professor Gates closes with a review of the current state of the field, and he looks at some denizens of the world of supersymmetry that he and his colleagues have recently identified.

31 min