July 24, 2017

Symmetry In Theoretical Physics

Symmetry in Theoretical Physics

From Newton to the Standard Model to GUTs to SUSY and Beyond

Abstract: Classical physics includes many important conservation laws which were established through experiment. Looking back these conservation laws can be explained as the consequence of symmetry. For the advancement of Modern Physics in the early Twentieth Century, theory, including applications of symmetry, played a vital role in the understanding of relativity, particle spin and anti-matter. Theoretical considerations of symmetries and broken symmetry led the development of the Standard Model of Elementary Particles, and these same considerations provide tantalizing clues to what may yet be discovered. This discussion will provide a high-level overview of these concepts without all of the mathematics and technical complications. The slides may be viewed here.

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Explore Particle Physics

symmetry

dimensions of particle physics

I, Dr. Rob, am a particle physicist. While theoretical physics is an amazing topic, it can be difficult to discuss with non-physicists. For that matter it can be difficult to discuss with physicists from other fields. I am thrilled to tell my friends about Symmetry Magazine. The articles are short, well written, and the photos and other graphics are incredible. If you wish you may subscribe for e-mail updates that contain links to the feature stories.


Symmetry Magazine -- Annus Mirabilis

One article that is especially interesting concerns Einstein’s most famous equation, E=mc2. The article is Einstein’s most famous equation, and it contains a fabulous video that is only two and one-half minutes long. It discusses how mass may be converted into energy, such as fusion or fission energy. It also discusses how new particles are created in particle accelerators like the LHC. Just click on the Annus Miarbilis figure shown, or go to the article link above. The visuals are very powerful, and the discussion is surprisingly easy to follow.

I choose to teach!

apple web size copyOur culture is the exponentially growing collection of knowledge and invention that we pass from one generation to the next.  Science and mathematics are especially rich components of our culture with millenia of contributions from many cultures and all regions of the globe.  Unlike other forms of inheritance which must be subdivided and are often distributed with inequity, this inheritance is the birthright of every person, and every person may consume as large a share as he or she would wish. Our world is one of science, mathematics and technology; literacy in these areas is essential for any individual who is to be engaged with and empowered in our world.  The curriculum is a subset of this inheritance which is distilled down and shared with students in the environment we call school.

The America that we know today was built by those who left their homelands because they were not first-born sons  and therefore had very limited birthrights.  Others came from situations where even first-born sons had few if any prospects.  With an education in America a person has prospects to not only survive but to thrive and to provide for children.  But if we measure the value of an education solely in terms of economic benefit, then we ignore the greater part of its value.Owl Box

In times past you might have been a  carpenter because  your father was a carpenter whether or not you were well suited for that occupation.  You might have been a mother and a housekeeper because it was expected,  but even learning to read was not a possibility.  Perhaps you would have been a field hand because that was the only option available.  Carpentry, parenthood  and farm work  are all important roles, and they bring joy to those who choose them.  However, with education you may choose to be a nurse, or a doctor or a software engineer because  the work suits you well.  And along the way you may sculpt your own identity;  you need not accept the identity that others force upon you.

Students do not always appreciate the awesome value of this cultural inheritance, so  a primary function of the teacher is to help the student understand the meaning of the curriculum with respect to the life of the student.  Once the student is engaged the teacher serves as  a guide.  Success is  achieved when the student is  able to function as the most important person in his or her own education.  A successful education system produces graduates who are life-long learners that are able to learn and grow with or without formal schooling.   I teach as a matter of social justice. I teach to empower students. I teach so that students may understand their world, be part of it, contribute to it and reap its rewards.  I teach because the rewards of working with students greatly outweigh the economic remuneration that comes with teaching.

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Book Review: The Fly in the Cathedral by Brian Cathcart

Fly in Cathedral

I thoroughly enjoyed this historical book about Cockcroft and Walton and the first time an atomic nucleus was split in the laboratory.  It brings to light an exciting era in science that most people only know from the lore of newspaper articles from decades ago.  This book has very broad appeal.

Most students of physics or chemistry learn something about Rutherford’s experiments that discovered the structure of the atom as a miniscule but very heavy nucleus surrounded by mostly empty space and some tiny and very lightweight electrons.  Rutherford used a radioactive substance as a natural source for alpha particles which were directed at a thin gold foil.  Most of the alpha particle passed through the foil with minimal deflection, and experimenters counted flashes of light when the particles hit a scintillating screen.

Flash forward to the search for the Higgs boson at the Large Hadron Collider at CERN in Geneva where custom designed particle beams of astounding TeV energies where protons infinitesimally close to the speed of light  are collided with each other.  In place of  human eyes and a scintillating screen is an amazing high-tech detector larger than a house, and all of the data are collected and analyzed with awesome computing power.

The story of Cockcroft and Walton at the Cavendish in Cambridge is a story of great experimental ingenuity.  Taking advantage of electricity which is newly available they generate the first synthetic particle beams.  There is a lot of work with high voltages and vacuum systems, and progress is difficult and dangerous.  The first experimentation with automated detectors begins.  Suddenly the field of nuclear physics  is alive, and immediately it is astonishing that, despite the challenges, it was at the same time easier than anticipated.

The name of the book?  That tiny nucleus in all of that empty space is like a fly in a cathedral.

Why is my logo an apple with a funny diagram on it?

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I wanted an attention-grabbing logo for my web site, but it had to be reasonably simple. I merged a few different physics concepts, and this is what resulted. It’s not really important for everybody to understand what it means to me.

I started with an apple. That much might be obvious as many people know the story about Isaac Newton. He made the incredible leap that the motion of a falling apple and the motion of stars and planets are determined by the same force called gravity.

The diagram drawn on the apple is slightly distorted due to the curvature of the surface of the fruit. This is suggestive of Albert Einstein’s General Theory of Relativity which describes gravity as the warped geometry of space-time. I actually got that idea from staring at the cover of Gravitation by Misner, Thorne and Wheeler.

The diagram itself is a Feynman diagram from Quantum Field Theory describing the interaction of three photon-like particles through the exchange of electron-like particles. The numeric value of this diagram is actually infinite, and it would indicate that the various components of the Standard Model of Elementary Particle Physics should fail. However, the contributions of the Electromagnetic, Weak Nuclear and Strong Nuclear forces conspire in such a way that the offensive infinities cancel exactly.

This very strongly suggests that the parts combine in a unified theory and is the basis of the idea of the Grand Unified Theory (GUTs). While such theories have not yet been experimentally successful it is generally believed that unification is manifest, and eventually gravity will be part of the unified theory, and we return full-circle to gravity.

In brief, this image represents to me the past, present and future of physics.

While the concept is mine, I wanted help from an artistic person who could go far beyond my white-board doodling. I thank Sharon Neveu for her excellent work!

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