Friday, May 31, 2013


Did you know that the Apollo 11 launch date of July 16 was also the anniversary of Trinity, the first atom bomb test performed in Alamogordo, New Mexico? The Manhattan project was a $2 billion effort that led to the birth of the atomic bomb. America’s space race, at a cost of $20 billion, culminating in the landing on the moon, was the obvious successor to that previous successful government and science project.

Now we think about the Silicon Valley entrepreneurs with their high caffeine energy drinks, take-out food, and chips are just following in the footsteps of the NASA engineers and their pocket protectors, Mexican takeout, evaporating hotplate coffee, and ashtrays filled with smoldering cigarette butts.

In so many ways, the race to the moon was a sequel to the preceding race for atomic mastery, including the competition with Russia. Both projects were driven by Third Reich émigrés. Trinity and Alamogordo are about 80 miles from the Apollo origins at Fort Bliss where von Braun’s rocket team practiced their art and only 120 miles from where the American rocket pioneer Robert Goddard tested the thrust of the same super-chilled fuels that would send Apollo 11 to the Moon.

These two great achievements of war time engineering, the first a hot war and the second a cold war, should be added to the other great American engineering accomplishments from the Erie Canal, the St. Lawrence Seaway, the Transcontinental Railroad, the Empire State Building, the Panama Canal, the Interstate Highway System, the Rural Electrification Administration and the Tennessee Valley Authority, Hoover Dam, telecommunications satellites, the Internet, and the Global Positioning System. These engineering accomplishments are a key force in the American identity. It was engineers who created these foundations of modern life, and our civilization could not exist without the big pipes, the vast roads, the power grids, the dams, and the people-and-cargo-carrying vehicles of heroic engineering and big science.

Often the study of ancient civilizations will focus on their engineering accomplishments from the pyramids of Egypt (and South America) to the buildings of Greece to the roads of Rome. Following the Renaissance, Galileo proved that the speed of a pendulum remains constant, a fact that his engineer son, Vincenzio, used to create an accurate pendulum clock. This shows engineering producing practical devices based on new scientific theories. However, sometimes the engineering precedes the scientific breakthrough. The steam engine, perfected by engineer James Watt, came before Sadi Carnot’s theories of thermodynamics based on the successful device.

At the founding of America, the political leaders recognized the importance of enlightenment and revered scientist and engineers, considering their work both an inquiry into the very stuff of the cosmos, and a contribution to the greater good of all of mankind.

Modern miracles were unleashed, including steel, refined petroleum, aluminum, and plastic used to build trains, trolleys, buses, subways, cars, planes, and jets. The darkness was pushed aside by the electric light bulb and indoor climates were changed by central heating and air conditioning as well as refrigeration. Soon came sewing machines, cameras, telephones, stoves and ovens, and washing and drying machines taking on the drudgery of everyday life. Movies, radio, television, and ultimately computers and video games transformed how we spent our leisure time.

These accomplishments were often celebrated by expositions and events displaying the technology of the age. London’s Crystal Palace of 1851 and France's Universal Exposition in 1889 with the construction of the Eiffel Tower to New York’s 1939 and 1964 World’s Fairs gave a preview of the technology that would transform modern civilization … a prediction that has become true in ways that those early celebrations would have never expected.

With the advent of computers, cell phones, and modern entertainment technology, our lives have been so transformed by the process and products of engineering that we are touched by it from the moment we’re awaken by our clock radios to the end of the evening watching the news or some other TV program on the over 200 channels available in the comfort of our own living rooms and bedrooms.

It is easy to spot a young engineer in making. That’s the boy (or girl … but sadly, usually the boy) who wants to know how things work. They may try to discover how through the process of disassembly. The desire to know how and why things work and the drive to understand the physical universe are common among those who have the title "engineer."

Often the first glimmer of interest comes from an erector set or a chemistry kit they encounter in their youth, or perhaps by the models of planes and rockets they build the in the quiet solitude of their room or basement. It can also come from the wild speculation contained in the science fiction genre. In our latest times these ideas may be sparked by computer games, the Science or Discovery channel on TV, or from movies and videos. It can come from looking up at the moon — or the stars — and imagining "seeking out new worlds and going boldly where no man has gone before."

I recall my childhood and those special Sunday nights when the Wonderful World of Disney would broadcast a program with a science theme — from an explanation of nuclear chain reaction to tales of space travel and rocket design. These were “Tomorrowland” presentations that were always my favorites.

The interesting back story here is that Walt Disney became obsessed with the idea of creating a California version of Copenhagen's Tivoli Gardens. Roy, his brother and the Walt Disney Company's business manager, refused to allow the corporation to invest in such a"crazy" scheme, so Walt convinced a fledgling television network ABC to offer $4.5 million in loan guarantees for the amusement park in exchange for a Disney television program, both to be called "Disneyland." The television version became America's most popular TV show, and when Disney and ABC wanted to create three episodes showcasing the "Tomorrowland" section of the park, producer Ward Kimball hired as on-air consultants three of Collier magazine's writers, including von Braun, the German rocket master, who was trying desperately to convince the US government of the possibility of a flight to the moon. (Actually Mars, but the moon was a good first destination.) A master at public relations, von Braun used these programs to spark the imagination of a nation.

So, on March 9, 1955, the premiere Disney episode, "Man in Space," effectively established von Braun as a national symbol of rocket science. He famously stated, "We can lick gravity, but sometimes the paperwork is overwhelming." Spoken as a true government employee. So imagine me, an eight-year-old kid, imagination stoked by the animations of rockets to Mars. Is it any wonder I ended up as an engineer. It's just surprising I didn't stow away on that first moon rocket!

Sadly, in our modern age of concern of terrorists and school shootings, that kids playing with gunpowder or chemicals … especially if explosions are involved … are strongly suppressed, often kicked out of school, and discouraged from their creativity. Coincidentally, just yesterday, I visited a robotic STEM project at a local elementary school here in Virginia Beach and spoke with the kids and observed them turning their ideas into practical applications that may some day police the beautiful beachfront, picking up litter and trash. The engineering spark is in their eyes as they don their protective goggles and drill, saw, and bolt together their vision of a litter collection robot. Today they will be competing in a 35 school challenge to see whose robot can best perform the task. "Hands-on," that's what makes an engineer. It was a most refreshing and inspiring visit by yours truly, and I was both impressed and enheartened by what I saw and heard.

Perhaps there will always be a division between engineers unable to engagingly describe their work to nonspecialists, and citizens uneducated enough to be interested in the details of science and engineering. As Carl Sagan once said, “We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.” It’s a modern day paradox.

I suppose I will always be a white-socks, pocket-protector, nerdy engineer, born under the second law of thermodynamics, steeped in steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow …

Science is about what is, and engineering is about what can be.

— Neil Armstrong

Although the twentieth century as a period of terror of war and struggles between nations and societies to overcome injustice with little respite in this current century, still technology has also enabled the reporting of these images and traumas and has brought images of these injustices and a conversation regarding their elimination into the homes of anyone with a television or a computer. John Pierce, the engineer who fathered Telstar, the first satellite to relay television signals across the Atlantic, said that engineering helped create a world in which no injustice could be hidden.

We have the tools to communicate and coordinate. You can thank the engineers for that. The question now is what to do with those tools. What will you do? Now I've got to go find my pocket protector. I know where my slide rule is.

Tuesday, May 28, 2013

Boom, Boom, Boom, Boom

I’m a member of the “me” generation — the baby boomers. Born between 1946 and 1964, this demographic group was conceived during the post-WWII baby boom and has flowed through life and the decades like a pig being digested by a boa constrictor — the lump clearly visible as it moved through the snake.

We rejected and redefined social norms. We were the hip generation. We truly invented rock and roll. Although the official statistics include the eighteen year range, it is the ’46 – ’50 group that led the way. We were teethed on black and white television and taken care of by stay-at-home mothers. We got what we wanted thanks to Dr. Spock, and we were the first to see Mr. Spock.

Our telephones had dials, and some didn’t even have that. We didn’t know terrorism, but we were afraid of the bomb. Our schools were overcrowded, yet we seemed to learn our basics. We were a special generation, maturing in the 60’s, we fought against the war wearing our peace signs and we fought in the war with our M-16s and agent orange. We invented rock and roll and danced in the streets while the cities burned with riots. We invented the artificial heart and the USB port … used in our invention: the personal computer. We invented DNA and Viagra, the world wide web and the Segway Personal Transporter, bar codes and music synthesizers, lithium-ion batteries and ethernet, and flat screen TVs. We’ve got more patents than any generation alive, and we’re now most of the congressmen and women running the country.

We saw the assassinations — of presidents, and leaders, and presidential candidates. We saw the war on our TVs and our cars had big fins. We were always fascinated by cars. Our cars were big and all had V-8’s in an era when gas was so cheap that “mpg” was a foreign term to us. We learned to drive stick shifts and now we’re in little European convertibles speeding down the interstate system that we built.

We discovered the Beatles and celebrated with Woodstock. Nothing like either has come since. Our shows were the Brady Bunch and Leave it to Beaver, celebrating home life with two parents and no swear words … Gilligan’s Island, the professor and Mary Ann … Rod Serling and Ed Sullivan that we watched on our parent's combination 25" TV and record player.

At the movies it was 007 … and still is … or Annette Funicello at the beach. For politics we had John F. Kennedy and Lyndon Johnson, Richard Nixon and Ronald Reagan. We continued to break records through our career days, inventing personal computers, the internet, and the cell phone, but leaving the discovery of social media to younger kids.

Now we approach retirement, forcing social security to fill sandbags in preparation for the flood. We recognize each other in the grocery store, spotting the gray hair and the beards and beads that never went out of style. We see each other on our Harley’s … flashing peace signs as we pass. We never grew out of style since we set the style.

We’ve got a few more good years in us before we move to the nursing homes and start to soup-up the wheel chairs and the (gluten-free) soup. Those that came after will never know the quiet of the 50’s before helmets on bicyclists or pictures of missing children on milk cartons or being strip searched at the airport. It was a simpler time before we started changing it.

We built the city on rock and roll. The music has never been the same since we discovered motown and Santana, or Janice and Jimi. We added the poetry of Bob Dylan and Jim Morrison to the amplified wailings of Hendrix and Led Zeppelin. We explored all the themes from Pink Floyd to Shocking Pink to Blues Magoos and Black Sabbath. We found harmonies in Crosby, Stills, and Nash, and in Peter, Paul, and Mary. The singer / songwriter with something to say was captured on record and eight-track tape as our music went mobile. Our big bands were just guitars and we discovered the sitar and world music … only to bend it to our own special use.

The guitar was the heart, but the Hammond Organ was the soul. There were the horns and even the flute of Ian Anderson too. It was a new time for music. The bands were in the garages until being signed to instant, overnight fame and fortune. We smoked, dropped, and even shot up every pharmaceutical and herb we could find, always trying to get higher.

Our skirts were mini and our shirts tie dyed … for real, not purchased at Wal-Mart. We communed with nature and tuned in, dropped out, and got high on LSD. We created a new world … a world focused on ourselves and creativity and trying new things. We grew up the generation of wealth and focus and we turned that into a greed driven lifestyle as we questioned everything.

We went from communes to condos and vacations on exotic beaches here and abroad, and stock markets and 401(k)s. But we’re not done yet. You have not heard the last of us. We’re those gray haired people in our pickup trucks and our motorhomes and our SUVs, and we are used to having things our way. We’ve broken the bank and the institutions along the way, and now we’re headed down life’s highway, not looking back at the wreckage we've left in our wake, but seeking what’s over the next hill. We weren’t the greatest generation. We had our sacrifices, but it was really, always, just about us. We were the spoiled generation that rejected materialism … for a while. We believed in truth and justice, and drove the civil rights movement and women’s liberation along with the “pill.” We non-conformed in a most conforming way, perfecting the "beat" philosophy from the fifties and going from mono to stereo to quadraphonic. We were always dancing, and thinking, and acting, and doing. We changed the style in a way that will never occur again.

We didn’t age well … fighting father time the whole way. Our stomachs grew like our bell-bottom pants as fast food sprang up across our nation. We were a particularly American phenomenon, and we changed the world … not always for the better.

It’s been a hell of a ride and the devil will be paid, but — for now — it’s “peace brother” and get out of our way. You will see us every day. We’re not as hip as we used to be, but don’t tell us that … we never listened and we’re not starting now. We’ve got our gray beards and our pony tails and we’re still hip. They even have radio stations dedicated to our music. We’ve got a few more years to go, continuing to change things to fit our desires. They’ll never see the likes of us again.

Thursday, May 16, 2013


I always wanted to be a scientist … or a teacher who taught science. I had that desire from a very early age; so early I can’t put a year to it. I do remember my first science fiction story, “Have Spacesuit, Will Travel,” by Robert Heinlein. Science Fiction was part of my “science” thing that began early. I got the book at the public library.

I know “Have Spacesuit …” was published in 1958 when I was 11 years old, but I have a letter from a professor at Stanford giving me a geology book in 1957. That was based on my interest in science from when he stayed at our motel in the summer doing geological work in central Montana.

So I put the start of my interest prior to that, making me 9 or 10 and in the fourth or fifth grade. Maybe it was sooner, I don’t know. I remember that my first goal was to be an astronomer. That probably went along with the science fiction I was reading. There are several other events I recall from elementary school time that reinforced my recollection of that early interest in science. Some were gifts. My parents gave me a record making machine. It consisted of a plastic disk you put in the center of a turntable over the top of blank record disks that came with the set. There was an arm with a pin that rode in groves in the center disk and a cutting needle connected to a microphone.

I know we lived at the motel at that time, so it was sometime between 1956 and 1960. I remember recording a “lecture” on Einstein’s theory of relativity and specifically the physics behind the limit of the speed of light. In my lecture, I performed my own personal Gedankenexperimente (or thought experiment as the German Einstein would say).

I described a large rocket ship with multiple engines going at a speed very near that of light. I proposed that you add one more rocket engine and explained why that would not push the rocket beyond the light-speed barrier. It is due to the increase in mass as you approach the speed of light. As you get closer and closer, your mass keeps increasing, so adding more velocity only increases the mass requiring even more rocket engines and you can’t get past the speed-of-light no matter how many additional engines are added.

I have no idea where I learned about Einstein and relativity other than the public library and science fiction and science nonficition books that I read back then. I know I was a avid reader and science was my only interest … I wasn’t reading the classics of literature.

I also remember a science set that my grandparents bought for me. It was a series of kits that arrived each month for about six or nine months. Each kit had tons of experiments and gadgets you would build that covered everything from electricity to optics to geology. My dad bought me a quality microscope from Edmund Scientific, and I bought tons of chemistry stuff at a local hobby shop.

My brother and I shared a large bedroom — a giant bedroom — in the basement of the motel under the new office my dad built. It had a small attached room for the water heater. I put in benches and lots of chemistry glassware and wooden test tube holders. I had lots of experiments going in that laboratory, and I put everything under the microscope.

Then my dad bought me a used Hallencrafters Short-wave receiver, and I became very interested in ham radio and electronics. At about 12 years old I was subscribed to “Popular Electronics” and I built a lot of electronic projects out of that magazine. I would order parts and chassis and stuff from Lafeyette Electronics in Chicago, and I saved up and bought a larger Hallencrafters radio and did that all through Junior and Senior High School.

At the end of the first year in Junior High, the seventh grade, we had an awards ceremony. I won an academic letter for my grades, but what really caught my eye was that some eighth grader got the “Outstanding Science Student of the Year” award. I made it my solemn goal to win that award in eighth grade.

I befriended the science teacher and spent a lot of time at his house. He had an excellent astronomical telescope, and I enjoyed the Montana evenings star gazing. I had a journal all through eighth grade science that I recorded my experiments and projects and I got A’s in all my classes. At the awards ceremony at the end of the year, I won a pin for my second year of academic achievement and I was the proud winner of the “Outstanding Science Student” award. It is a beautiful blue ribbon pin with a microscope on the silver pendant. I’ve still got it here in my little collection of memorabilia.

Things were to change though once I entered High School. We had a four year school with Freshman, Sophomore, Junior, and Senior grades. At that time in Montana, you could get your drivers license at 15. The summer after Junior High my grandma helped me buy my first motorcycle, and I rode it until the cops insisted I stop or they'd take it away. So I waited somewhat impatiently for my birthday to roll around so I could get my official license.

As my friends all started driving that Freshman year, my interest in school declined. I often explain that I got distracted by “wine, women, and song,” but not necessarily in that order. The distraction started a bit in Junior High. I did a lot of dating and going to dance parties in seventh and eighth grade. No alcohol, just girls and dancing. I had an agate ring … everyone in Montana had an agate ring … and I was going steady with one girl after another. I’d go to a party going steady with one girl, break-up, get my ring back, and be going steady with a second before the end of the party. Those really were the “good old days.”

By High School the partying got a little more serious. I discovered beer and got more involved with music and just quit doing homework. I was smart enough to get by without a lot of studying, but the A’s became B’s and even sometimes C’s. Still, I did take the toughest classes … the so-called “College Prep” curriculum, but I rarely made the honor role and just didn’t really care. Too much fun I guess.

After High School, naturally I went to college, but where to go? I had considered Stanford or Cal Poly and even DeVry Institute in Chicago. But, I didn’t have any serious plans and my dad suggested the Montana School of Mines, so off I went. I was even a worse student there. Not only didn’t I study, I didn’t even go to class. I was playing guitar, drinking beer, hitch hiking to different towns on the weekend, and the only reason I lasted all year was that it took two semesters for me to fully flunk out. I took Calculus and Chemistry and all the tough subjects the first semester and the only class I passed was Weight Lifting … a PE class. The second semester I took history and sociology and economics, all those fluffy courses, but again I didn’t go to class and flunked everything … except Weight Lifting. What a waste of my parent's money.

I didn’t care. As long as I had a couple of beers, a car, my guitar, friends and girls, it was a blast. Of course this was at the start of the Vietnam war, and I was soon drafted. I broke my arm in a car accident, so the military was delayed a year, but, by the time I was 20, I was in the Navy. I still wanted to go scientific and loved electronics, so I enlisted for six years on a deal that the Navy would give me two full years of electronics training.

I was very successful in that training, graduating top in my class from every Navy school except one, where I graduated second. Because of my good grades, I was enrolled in a special Air Force school and learned electronic test equipment calibration at the National Bureau of Standards in Boulder. While in school I also got to do some teaching and really enjoyed that.

While in the Navy I took a couple of classes at Old Dominion University in Norfolk, Virginia, but I was still into partying and music, so that wasn’t really a focus although I got good grades. I got out of the Navy, moved to Colorado, found a job working as an electronics technician, and started studying electronics at Metropolitan State College.

During the latter part of that schooling, I was working as a teacher at Electronics Technical Institute and getting straight A’s in college. Maybe it was because of my background from the Navy and my experience teaching, often teaching the same text book that I used as a student at the college, but I just breezed through the math and science and even the English and liberal arts courses. The only class I didn’t get an A in was a one credit course that was part of “Senior Project.” My project design only got a B. I did get an A in the second semester when I built the project, and the professor even said he wished he’d given me a better grade in the first semester.

So I graduated from Metro with a Bachelor’s degree in Electronics Engineering. I had a 3.97 GPA and graduated Summa Cum Laude — with highest honors. All through school I got scholarships and awards, and I seemed to really be on my way.

I went to work for IBM, but I still had some years left on my GI Bill, so I enrolled at the University of Colorado pursuing a Master's degree in mathematics with a minor in physics. But now things changed. Graduate math courses were very, very hard. I struggled and only got B’s and even a few C’s. One professor told me I was in the wrong class. I was taking “Advanced Calculus” and he said I should take “Advanced Calculus for Scientists and Engineers.” He said that would be easier and better fit my background and undergrad degree.

I explained that I had changed my major and was working on a Master's in Math. He just shrugged. I did better in the physics classes, but the math was always hard … very, very hard for me.

I recall taking an “Abstract Algebra” class. I would start on the homework with problem one. If I couldn’t figure it out, I moved on to problem two expecting to come back to problem one. I did the same with problems two, three, and four. By the time I got to the last problem, I realized I had not figured out a single question … I had skipped them all. It was at this time I discovered the public library as a quiet place to study.

IBM had a video education program with Colorado State University and it was free, so I started taking Abstract Algebra at CSU at the same time I was taking it at CU. Having two different perspectives from two different teachers helped a bit, and I ended up with a C in the first semester at CU. I buckled down and doubled down the second semester and got a B. To this day I’m prouder of that B than all the A’s I ever got.

I did finish with an acceptable GPA of 3.04, but that was more due to my A’s in physics that made up for C’s in math. I did think I was getting better toward the end and one professor said that my grades in the last few classes were surprising considering my earlier progress. It was a small college (part of a large university) and I had several professors more than once.

My lack of success was not due to the quality of teaching, but it was my difficulty. I did all this college part-time while working full-time. That, plus the GI Bill and scholarships, and even tuition assistance from IBM the last three years made it no problem financially. That was important because I had a family and needed to makes ends meet. However, I do think full-time school and a total immersion in the curriculum would have helped me with the math. Still, I made it.

Meanwhile I was doing very well at work and moving into new fields and being very successful. I joined IBM Technical Education and, for fourteen years, I taught IBMers and customers. It was during this time that I changed careers from Electronics Engineer to Software Engineer. That’s a story for another blog, but it did create a problem for me since my formal training was not programming, with the exception of a few Pascal classes.

However, my travel schedule with Tech Ed prevented my from going back to college. IBM gave me a lot of classes and I ended up graduating from IBM’s University Level Computer Science program, but I wanted more. What I really desired was a doctorate.

The problem was that I had done so many different things, I could not decide what area I wanted to get a Ph.D. in. I considered Electronics Engineering, but I hadn’t done that for ten or more years. I considered math, but my struggle with my Master’s sort of cooled those jets. Plus I hadn’t used my math in ten or twenty years, so it was rusty. I also thought about a Ph.D. in Education, specifically "Instructional Design," something I had a lot of experience in and had even published. But there was no way I could go back to college with my travel schedule.

Finally, I decided to get another Master’s in Computer Science. I left IBM Education and went to work in IBM Printing Systems running the software testing lab. I enrolled at the University of Denver and got my CompSci Master’s in 2003. I didn’t get straight A’s, but I did quite well, graduating with a 3.53 GPA. No high honors, but, again, it was night school attended by a full-time worker, and I did miss a few classes due to business travel, so I was happy with the result.

Upon retirement some ten more years later, I’ve finally gotten myself into a Ph.D. program at one of the most prestigious universities in the country: Stanford University in Palo Alto, California. I’m currently preparing for my qualification exams or “quals,” and I’ve struggled a lot with some of the subjects. I'm pursuing a degree in physics. The problem appeared to be related to the mathematics, so I’ve changed direction slightly and I’m now taking some more math courses before I return to the advanced physics. I’ve had to reset my expectations and I’m dealing with the fact that my undergraduate and graduate work was so many years ago. It’s coming back, but a lot slower than I expected.

So that’s the story of my roller coaster ride. I went from flunking out of the School of Mines to graduating from Navy technical school at the top. I got a job teaching and earned a Bachelor’s degree summa cum laude.

I then struggled with math and barely survived my first experience of graduate school.

Twenty years later I earned a second Master’s degree, again in a subject I was already well trained, graduating in the top 10% (I think … they didn’t have rankings). So it’s been down — up — down — up … and now I’m on a downer.

When I first started at Stanford the classes went well. I zoomed through classical physics, running into a little trouble with Lagrangian and Hamiltonian Dynamics, but I no longer seek straight A’s, so I survived. I then hit a bit of a brick wall, and had to regroup in January. That has gone pretty well with finals next week.

I have a conference call with my adviser today at 9:00. Soon I’ll know. Wish me luck.

Tuesday, May 14, 2013

History of Science -- Part Twenty-Five: Atom Smashers

Particle accelerators are devices that cause atomic particles such as electrons, protons, and even entire nuclei go real fast and then smash them into targets. Some targets are stationary and some are moving in the opposite direction to get the maximum impact. Some accelerators are linear or straight line like a drag strip and some are circular and the particles go round and round and round like a race track.

Progress in particle physics and the resulting gradual discovery of the fundamental properties of the universe is based upon the progress in particle accelerators. Progress in particle accelerators is measured by the higher and higher “resolution” or “magnification” that comes with the acceleration of particle beams to higher and higher kinetic energies.

The first accelerators in the early 1930’s utilized direct voltage to accelerate ions to energies of a few hundred keV (thousand electron-volts), resulting in the first induced nuclear disintegration in 1932. High voltage sparking limited these first accelerators to less than 1 MeV, and new ideas were needed to push past the 1 MeV barrier. The concept of resonant acceleration provided this impetus in the 1940’s by the application of radio frequency (RF) electric fields oscillating in resonance with the particles passing through a series of accelerating gaps. This led from the linear accelerator to the cyclotron, where another seemingly impassable energy barrier was reached at approximately 25 MeV.

Recall that an "electron-volt" is the energy of an electron when accelerated through a potential difference of one volt. You can give the electron (or any other particle) all the kinetic energy in one single potential across a gap, or you can give it multiple kicks from multiple gaps. This is similar to pushing a child in a swing. With each push you add more kinetic energy instead of doing it all in one big shove.

Then came the principle of phase stability, which allowed the invention of the synchrocyclotron and synchrotron, and the energy barrier was pushed up to 2 GeV by the early 1950’s. (Consider "phase stability" as pushing on the child's swing at just the top of the arc, thereby maximizing the energy transferred to the swing.) In the 1950’s came alternating gradient focusing, allowing a dramatic reduction in magnet size in large accelerators, and the barrier moved again to 400 GeV. Then came the concept of colliding beams in the 1960’s, and the energy frontier moved dramatically forward. Super conducting magnets and computer control is the current state of the art. We are limited in the 21st century only by the prohibitive cost of building new accelerators, and the question of where to build them.

Earlier I described Ernest Rutherford’s experiment firing α-particles at a thin sheet of gold foil and discovering, to his amazement, that some of the particles (which are helium nuclei containing two protons and two neutrons) bounced back. This showed that atoms had a very dense, yet tiny central core or nucleus.

A decade later he used α-particles of about 5 million electron volts (MeV) to produce radioactive isotopes and to disintegrate nitrogen nuclei. He then challenged the scientific community to develop devices that would accelerate charged particles to energies greater than those occurring in natural α-decay.

This led to the development of an accelerator at the Cavendish Laboratory in Cambridge, England in 1930. They achieved energies in the 500-800 kV range and made new discoveries when they smashed protons into a lithium nucleus creating α-particles.

In 1930, Robert J. Van de Graaff, developed the generator named after him. It was a simple affair consisting of large metal globes fed electrons by rubber belts. I’m sure all my readers have seen such sparking globes in old Frankenstein movies. The simple device created potential difference of about 1.5 MV, but sparking continued to limit greater energy levels.

Modern Van de Graaff generators can produce as much as 15 MV, but the next big advancement came from the use of multiple gaps that used lower voltages, but several stages to increase particle acceleration. These devices are fed radio frequency alternating voltages and this is what we call the betatron.

A research team working at the University of California at Berkley used this form of acceleration in a round container and created the first cyclotron that spun the particles around and around. That way the particles get a push on each revolution, again like the child in the swing. These devices could accelerate heavy particles such as protons and helium nuclei to several million eV. There were many technical problems that were solved, and by the 1960s there were over a hundred cyclotrons in laboratories all around the world.

The betatron, which accelerated electrons, was also subject to design improvements that led to the concept of phase stability and the use of both radio frequency electric and magnetic fields to synchronize particles in a well-defined orbit producing the syncrotron with energies in the several hundred MeV. Further advances in magnet designs led to the cosmotron, so named since it could match the energy level of cosmic rays. The next advance was the ability to focus the beam of particles and energy moved into the GeV range.

Two types of accelerators were being utilized. One uses speeding electrons. Since they are much smaller and less massive than protons, they made fine subtle measurements of atomic structure. The other designs using protons and atomic nuclei were much better at “smashing,” but the larger particles could mask subtle effects.

In 1966 Stanford University built a linear accelerator called SLAC for Stanford Linear Accelerator Center. It was two miles long, buried 25 feet underground. A number of new particles were discovered at SLAC leading to several Nobel prizes. The device continues to be upgraded and improved, but it has been eclipsed by machines with greater power.

I’ve mentioned CERN often in this quantum history. The name CERN is derived from the acronym for the French Conseil Européen pour la Recherche Nucléaire, a provisional body founded in 1952 with the mandate of establishing a world-class fundamental physics research organization in Europe. This research facility is funded by several European nations.

In 1969, CERN started construction on two large, connected rings located on the border between Switzerland and France. When the facility was being built, they dug tunnels large enough to add a more powerful accelerator at some point in the future. CERN was the first proton-antiproton collider and added much to the knowledge of fine atomic structure.

In 1983 the Tevatron was constructed in Illinois and pioneered some of the engineering practices that CERN would follow with their future construction of the Large Hadron Collider. The Tevatron moved energies into the Terravolt range.

Since the 1960’s had produced a fascinating theory predicting a new particle eventually called the Higgs boson and since that particle would complete the jigsaw puzzle of messenger particles and complete what is called the “standard model,” there was a lot of effort to build an even larger collider to explore the energy levels at which the Higgs boson would appear.

In 1993 the Superconducting Super Collider (SSC) was planned for Texas and construction began. However, soon Congress dropped its budget and left it incomplete. Eventually CERN gained the backing of the important European nations and the Large Hadron Collider, the world’s most powerful accelerator, was built in the original tunnels of its predecessor and went operational in 2008 after an initial failure that took over a year to repair. Now it is functioning producing energy in the range of 7 TeV in its 17 mile circumference ring.

Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide. The beams travel in opposite directions in separate beam pipes — two tubes kept at ultrahigh vacuum. Obtaining a collision is actually very difficult. The two beams that meet head-on are like a fog and actual particle collisions are very rare. CERN compares it to firing two needles at each other from 10 km away and hitting head on. It is like two shotgun blasts aimed at each other … some pellets … some times … will hit head on. The collisions do occur, because there are millions of particles in each stream and they go around the ring in microseconds for another opportunity to collide. So, even though a single collision is rare, there are billions and billions of opportunities and impacts occur on a steady basis and the results of these impacts are studied. At four places on the ring the beams are compressed and aimed at each other.

Some 1,232 dipole magnets keep the beams on their circular path, while an additional 392 quadrupole magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. Approximately 96 tons of liquid helium is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (−271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature.

Six detectors have been constructed at the LHC, located underground in large caverns excavated at the LHC's intersection points. The detectors at the LHC are built around the collision points where the particle beams meet head-on and they are designed to track the motion and measure the energy and charge of the new particles thrown out in all directions from the collisions. The LHC detectors are very large, for example ATLAS is the size of a 5 story building. Their great size is necessary firstly, to trap high energy particles traveling near the speed of light and secondly, to allow the tracks of charged particles to be detectably curved by the detector magnets.

Detectors are typically made up of layers, like an onion, with each layer designed to detect different properties of the particles as they travel through the detector. The layers nearest to the collision point are designed to very precisely track the movement of particles, especially the short-lived particles that are both the most difficult to detect and the most interesting to the researchers.

Subsequent layers track the movement, and also slow down and stop, longer-lived and more energetic particles. As these particles are slowed down they release energy that is measured by calorimeters in the layer.

Detectors usually include a powerful magnet; this affects the motion of charged particles produced in collisions and from the extent of its effect researchers can measure the charge and momentum of particles. Through measurements of momentum, mass can be deduced.

Over the last few years, the power of the Large Hadron Collider has been gradually increased. It will be a few more years before the atom smasher is running at full power. In the mean time, there is a lot of data being produced that has to be analyzed and compared. Some of the events that are sought are rare and some particles only “live” for a very, very short amount of time before they disintegrate into other particles. So often the data analysis is to find the secondary or tertiary products of the original particle. It isn’t just looking for a needle in a haystack, but for the bent piece of straw that the needle left behind.

The data collected in the detectors is sent to researchers all over the world. Of course, the data is processed in powerful computers. In order to facilitate the transmission and analysis of the detector data with maximum efficiency, the world-wide network provided by the Internet is used. In the early days of CERN operation, before the LHS was built, this problem of data sharing led to a unique solution.

In order to deliver this data to research labs and universities all over the world, in 1984 a researcher at CERN, Tim Berners-Lee, developed a new graphical interface and system (HTML) for the Internet which he named the “World Wide Web.”

The first Web server was a Next Cube created by the company founded by Steve Jobs after he was forced out of Apple in the 80’s, which Berners-Lee got in September 1990, and it was in December of that year that the Web was established between just a couple of CERN computers. Berners-Lee also used the Next computer to develop and run a multimedia browser and Web editor.

So, that’s the story of particle accelerators, brought to you by this spin-off technology called the WWW. Now, what about the Large Hadron Collider? Did it find the Higgs boson? And why is the Higgs particle so important that the Nobel laureate from the Illinois Institute of Technology, Leon Lederman wrote about it in a book called “The God Particle: If the Universe is the Answer, what is the Question?” Hyperbole for certain, but still a very good question.

Well, keep your eye on the world wide web, because the answer to those questions will be the subject of the next chapter, brought to you via that very same WWW.

This then is the process of quantum theory advancement. Sometimes new discoveries are made in the experimental laboratories that lead to new theories to explain the unexpected results. Other times theory is ahead of experiments and predicts results that take years to be verified in the laboratory. In 1960 the Higgs boson was predicted, but it took over 40 years for the experimental devices to reach the energy range to reproduce the theoretical particle and verify its actual existence. Next is the story of that particle.

Monday, May 13, 2013

History of Science -- Part Twenty-Four: Quarks

Murray Gell-Mann
Physicists Murray Gell-Mann and George Zweig, working separately, each prosed the possibility of the quark in 1964. Its unusual name was chosen by Gell-Mann, who saw the word "quark"  used as a nonsensical term in James Joyce's Finnegans Wake (1939) and liked the sound of it. The line "Three quarks for Muster Mark…" appears in the fanciful book.

Zweig, a 1959 graduate of the University of Michigan, also proposed the existence of quarks while a graduate student in physics at the California Institute of Technology in 1964 (independently of Murray Gell-Mann). Zweig dubbed them "aces" after the four playing cards, because he speculated there were four of them.

Murray Gell-Mann received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. He is a Professor of Theoretical Physics Emeritus at the California Institute of Technology, a Distinguished Fellow and co-founder of the Santa Fe Institute, Professor in the Physics and Astronomy Department of the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.

He introduced the quark constituents of all hadrons, having first identified the SU(3) flavor symmetry of hadrons, now understood to underlie the light quarks, extending isospin to include strangeness, a quantum number which he also discovered.

He developed the V−A theory of the weak interaction in collaboration with Richard Feynman, and he introduced "current algebra" as a method of systematically exploiting symmetries to extract predictions from quark models. This provided starting points underpinning the development of the standard theory of elementary particles.

Gell-Mann was born in Manhattan into a family of Jewish immigrants from the Austro-Hungarian Empire. His parents were Arthur Gell-Mann and Pauline Reichstein. Teaching himself calculus at the age of seven years old, Gell-Mann quickly revealed himself as a child prodigy.

Propelled by an intense curiosity and love for nature and mathematics, he graduated valedictorian from the high school and subsequently entered Yale at the age of 15 where he earned a bachelor's degree in physics in 1948, and a Ph.D. in physics from MIT in 1951.

In 1958, Gell-Mann and Richard Feynman, both professors at CalTech discovered the chiral structures of the weak interaction (in parallel with the independent team of George Sudarshan and Robert Marshak).

Gell-Mann's work in the 1950s involved recently discovered cosmic ray particles that came to be called kaons and hyperons. Classifying these particles led him to propose that a quantum number called strangeness would be conserved by the strong and the electromagnetic interactions, but not by the weak interactions. Another of Gell-Mann's ideas is the Gell-Mann-Okubo formula, which was, initially, a formula based on empirical results, but was later explained by his quark model.

In 1961, this led him (and Kazuhiko Nishijima) to introduce a classification scheme for hadrons, elementary particles that participate in the strong interaction. Gell-Mann referred to the scheme as the Eightfold Way, because of the octets of particles in the classification. (The term is a reference to the eightfold way of Buddhism.) Although now retired from teaching, he is still active in the scientific community and spoke at the “World Economic Forum” in 2012.

As discussed previously, in ordinary matter, the strong force acts only in the nucleus and it is due to the presence of the quarks, the ultimate basic particles from which protons and neutrons are formed. As the electric and magnetic forces are effects arising from electric charges, so is the strong force ultimately due to a new variety of charge, which is carried by quarks but not by leptons. Hence leptons, such as the electron, are not affected by the strong force; conversely, particles such as protons and neutrons that are made of quarks do feel the strong force.

The laws governing this are fundamentally similar to the those for the electromagnetic force. Quarks carry the new charge in what we can define as the positive form, and so antiquarks will carry the same amount but with a negative charge. The attraction of opposites then brings a quark and an antiquark together. The quark-antiquark particles are called mesons. (Note that the antiquark is not the same flavor as the quark. Otherwise the antimatter antiquark and the quark would be destroyed. For example, it might be an u quark with a d antiquark.)

Baryons, which are made of three quarks, don’t bond with this “+” / “−” bond, but another characteristic is the cause of the strong force.

It turns out that there are three distinct varieties of the strong attraction and to distinguish among them we call them red (R), blue (B), and green (G). As such they have become known as color charges, though this has nothing to do with color in the familiar sense — it is just a name.

As unlike colors attract, and like repel, so would two quarks each carrying a red color charge, for example, mutually repel. However, a red and a green would attract, as would three different colors, RBG. Bring a fourth quark near such a trio and it will be attracted to two and repelled by the third which carries the same color charge. The repulsion turns out to balance the attraction such that the fourth quark is in some sort of limbo; however, should it find two other quarks, carrying each of the two other color charges, then this trio can also tightly bind together. Thus we begin to see the attraction of trios, as when forming protons and neutrons, is due to the threefold nature of color charges. As the presence of the electric charges within atoms leads to them clustering together to make molecules, so do the color charges within protons and neutrons lead to the clusters that we know as nuclei.

The underlying similarity in the rules of attraction and repulsion give similar behavior to the electromagnetic and strong forces at distances much less than the size of an individual proton or neutron. However, the threefold richness that positive or negative color charges have in comparison with their singleton electric counterparts leads to a different behavior in these forces at larger distances. The color-generated forces saturate at distances of around 10-15 meters, the typical size of a proton or neutron, and are very powerful, but only so long as the two particles encroach within this distance — figuratively “touch” one another — hence the color-induced forces act only over nuclear dimensions. The electromagnetic force, in contrast, acts over atomic dimensions of some 10-10 meters when building stable atoms, and can even be felt over macroscopic distances, for example the magnetic fields surrounding the earth.

Based on this new theory of “color” charges, the study of quarks and the understanding of the nucleus and the strong force is called Quantum Chromodynamics or QCD in analogy to Quantum Electrodynamics or QED.

Since quarks can’t be isolated singularly due to a phenomenon known as color confinement, quarks are never directly observed or found in isolation; they can be found only within hadrons, such as baryons (of which protons and neutrons are examples), and mesons. For this reason, much of what is known about quarks has been drawn from observations of the hadrons themselves.

In seeking a deeper explanation for the regularities of the SU(3) classification scheme, Gell-Mann invented quarks. In this approach there are three fundamental quarks dubbed “up,” or u, “down,” or d, and “strange,” or s — and their antiparticles, the antiquarks. Mesons are built from a quark plus an antiquark, while baryons are composed of three quarks. The proton is a combination of two up quarks plus a down quark (written uud), for example, while the neutron is made of an up quark plus two down quarks (udd).

By assigning a charge to the up quark of + 2/3 e (where − e is the charge on the electron) and − 1/3 e to the other two, the charges on all the known mesons and baryons came out correctly.

But the idea of fractional charges was not accepted by physicists of the day; in his original paper, Gell-Mann even wrote that “a search for stable quarks of charge − 1/3 or + 2/3 at the highest energy accelerators would help to reassure us of the nonexistence of real quarks.”

After several years of fruitless searches, most particle physicists agreed that although quarks might be useful mathematical constructs, they had no innate physical reality as objects of experience.

However, experiments run at the Stanford Linear Accelerator (SLAC) from 1967 to 1973 were eventually interpreted to indicate the actual existence of fractional charged objects within the proton and neutron. In 1973, experimental and theoretical developments had produced a coherent picture of the nucleon as composed of fractionally charged quarks plus neutral gluons. Quarks do exist!

Quarks and Leptons are the building blocks which build up matter, i.e., they are seen as the "elementary particles". In the present standard model, there are six "flavors" of quarks. They can successfully account for all known mesons and baryons (there are over 200).

The most familiar baryons are the proton and neutron, which are each constructed from up and down quarks. Quarks are observed to occur only in combinations of two quarks (mesons), three quarks (baryons). (There is a theoretical combination of five quarks, but it has not been found in experimental data … at least not yet.)

So a proton, consisting of two up and one down, has a total charge of

2/3 + 2/3 − 1/3 = + 1.

A neutron, on the other hand, is two down and one up for

−1/3 −1/3 + 2/3 = 0.

These were the simple equations written on napkins by Gell-Mann when he supposed that the nucleons were made up of three charged particles. It was a simple math trick … yet it turned out to be what Nature had hidden in the nucleus all along.

Each of the six "flavors" of quarks can have three different "colors". The quark forces are attractive only in "colorless" combinations of three quarks (baryons), quark-antiquark pairs (mesons) and possibly larger combinations such as the pentaquark that could also meet the colorless condition. Quarks undergo transformations by the exchange of W bosons, and those transformations determine the rate and nature of the decay of hadrons by the weak interaction.

The property of quarks labeled color is an essential part of the quark model. The force between quarks is called the color force. Since quarks make up the baryons, and the strong interaction takes place between baryons, you could say that the color force is the source of the strong interaction, or that the strong interaction is like a residual color force which extends beyond the proton or neutron to bind them together in a nucleus.

Inside a baryon, however, the color force has some extraordinary properties not seen in the strong interaction between nucleons. The color force does not drop off with distance and is responsible for the confinement of quarks. The color force involves the exchange of gluons and is so strong that the quark-antiquark pair production energy is reached before quarks can be separated. Therefore, you won’t see any quarks in isolation.

Another property of the color force is that it appears to exert little force at short distances so that the quarks are like free particles within the confining boundary of the color force and only experience the strong confining force when they begin to get too far apart. The term "asymptotic freedom" is sometimes invoked to describe this behavior of the gluon interaction between quarks.

We now recognize six flavors of quarks (plus six more antiquarks).

Quark Symbol Charge
Up u + 2/3
Down d − 1/3
Charm c + 2/3
Strange s − 1/3
Top t + 2/3
Bottom b − 1/3

So if protons and neutrons are not fundamental particles, but are actually made up of even smaller particles called quarks, why not suppose that quarks are made of even smaller particles … possibly blue and called “smirfs”? What indeed?

There is an ancient cosmological myth that describes a flat earth riding on the back of a turtle. When asked, “what holds up the turtle,” the jocular answer given was “turtles all the way down.” That is, the turtle rode on the back of another turtle, sort of an infinite regression. Stephen Hawking made the expression famous in a 1988 book. It is sort of the chicken and egg conundrum, but in the case of sub-atomic particles, we don’t believe there are any more turtles.

The latest theories propose that quarks are actually made up of strings … vibrating strings … vibrating in more than three or four dimensions; maybe as many as 29 dimensions. String theory naturally incorporates gravity, and is therefore a candidate for a theory of everything, a self-contained mathematical model that describes all fundamental forces and forms of matter.

Isn’t it odd that I started this journey with the Greeks and their vibrating musical instrument strings suggesting a simple order to the universe … and we now end with vibrating “super strings.”

However, that theory will require a lot more powerful atom smashers to explore. The latest and largest smasher is the Large Haldron Collider in Switzerland at CERN. Our story continues there … next time.

Thursday, May 9, 2013

History of Science -- Part Twenty-Three: Fundamental Forces

Wolfgang Pauli
The History of Physics has gone through many stages. I don’t mean just this narrative, I mean the actual history. In Newton’s age the idea of force via contact was popular. Everything was billiard balls bouncing off each other. It was the contact that transferred the force.

One interesting aspect of that model is that time could run backward. The rules of physics worked exactly the same in reverse as they did in forward gear. Imagine a cue ball hitting two other balls that are sitting touching. The two other balls would fly apart at some angle from the force of being hit by the cue ball. Now imagine the reverse. The cue ball sits still and is hit by two balls coming in at an angle. They stop and the cue ball flies backwards. The rules of physics worked the same in both directions. In a sense, time was reversible. That was force transferred by contact.

The solar system presented a bit more of a problem. Where was the contact with gravity? I suppose some still considered the crystal spheres, but just how gravity worked over a distance was not understood and Newton refused to give a hypothesis.

Later, taking the lead from iron filings behavior around a magnet, electromagnetics in Maxwell’s time was all about fields. It wasn’t force at a distance, but rather fields that particles followed. Einstein finalized that view with his general theory of relativity that showed that gravity was just planets responding to the distortion of space-time similar to bowling balls rolling down the gutter at the bowling alley. However, theories and later experiments proved that these fields fluctuated and "emminated" from the source of the force.

As scientists dug into how atomic particles followed the old and new fundamental rules of force, they actually went back to Newton’s perspective of force through contact. Using Einstein’s equivalency of mass and energy, they supposed virtual particles that would be created from energy to carry the force from one object to another. This theory of “force carriers” or “messenger particles” helped explain the zoo of subatomic objects that appeared in high energy collisions of tiny matter.

In this episode of “The History” we will look again at the four fundamental forces in review and introduce the force particles proposed to be basic to the individual forces. These force carriers or messenger particles would also obey the rules of the quantum world and would have properties such as mass, momentum, and even angular velocity or spin.

At the temperatures common to our world, four discrete forces govern the interactions of matter — gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. Each force is carried by a separate messenger particle unique to it. The strong force is by far the strongest of the forces, followed by the electromagnetic force, the weak force, and finally the extremely feeble gravitational force. Though these four forces govern every matter interaction, a theory that unites them all is still being sought.

As I explained, there is a unique messenger particle associated with each of the four fundamental forces. These particles can be considered the "smallest amount" of each force than can exist in nature. Experiments have confirmed the existence of three of the four particles, but the graviton has yet to be discovered. Calculations show that it should be massless. Although the other three forces are thought to be the result of a single particle, the weak force messengers or "gauge bosons" come in two separate varieties with different masses.


Gravity, the force we discussed first in this history, is the weakest of the four forces. It is about 10-36 times the strength of the strong force. This weakness is easily demonstrable — on a dry day, rub a comb across your shirt to give it static electricity, then hold it over a piece of paper on a desk. If you were successful, the piece of paper lifts off the desk. It takes an entire planet to keep the paper on the desk, but this force is easily overcome with everyday materials employing the electromagnetic force.

However, the range of gravity is unlimited — every object in the universe exerts a gravitational force on everything else. The effects of gravity depend on two things: the mass of two bodies and the distance between them. In more precise terms, the attractive force between any two bodies is directly proportional to the product of the masses and inversely proportional to the square of the distance between the bodies. The dominance of gravity on macroscopic scales is due not to any intrinsic strength but instead to its enormous range and constant attractive nature, especially as compared to the other forces. (On a universal scale, the more powerful electric force tends to be balanced out. The positive and negative poles cancel each other out in large systems.) These properties of gravity have made it extremely difficult to incorporate gravity into modern theoretical frameworks.

The messenger particle of gravity is the graviton. It has not been experimentally verified, mainly because it is extremely hard to find the smallest denomination of the weakest force. (In addition, gravity “waves” have also been proposed, but also not verified experimentally.) Recent calculations indicate that the graviton will likely be massless, which makes it even harder to detect.

Interestingly, all versions of modern string theory incorporate gravity (unlike previous quantum theories) and not only allow but require a particle with the properties of the graviton. Its discovery will likely represent a major victory for string theory, since previous quantum theories based on the model of point particles give illogical, infinite answers when gravity is incorporated.


The electromagnetic force is actually second in effective strength to the strong force, but it is listed out of order here because it, like gravity, is more familiar to most people and this is the order we discussed them in “The History.” Its strength is less than 1% of that of the strong force, but it, like gravity, has infinite range. However, unlike gravity, electromagnetism has both attractive and repulsive properties that can combine or cancel each other out. Whereas gravity is always attractive, electromagnetism comes in two charges: positive and negative. Two positive or two negative things will repel each other, but one positive and one negative attract each other. This can be neatly illustrated by magnets: two "alike" poles will repel each other, but two opposite poles attract each other.

This is the principle that keeps atoms together: the positively charged nucleus and the negatively charged electrons attract each other. This is also the explanation of atom sizes: more electrons have greater repulsive force, so atoms with more electrons are larger because of the electrons' mutual repulsion. Similarly, atoms with larger nuclei and the same number of electrons are smaller overall because they exert a greater attractive force on the electrons.

The messenger particle of electromagnetism is the photon, a massless particle that logically (since light is a manifestation of electromagnetism) travels at the speed of light (299,792,458 meters per second or 186,282 miles per second).

The Strong Nuclear Force

The strong nuclear force is one of the less familiar fundamental forces. It operates only on the extremely short distance scales found in an atomic nucleus. Its "duties" are keeping quarks together inside protons and neutrons, and thereby keeping protons and neutrons inside atomic nuclei. Its messenger particle is the massless gluon, so named because it "glues" elementary particles together.

The Weak Nuclear Force

The weak nuclear force is the other unfamiliar fundamental force. Like the strong force, its range is limited to subatomic distances. The weak force is responsible for radioactive decay. In actuality, it is stronger than electromagnetism, but its messenger particles (W and Z bosons) are so massive and sluggish that they do not faithfully transmit its intrinsic strength.

In fact, the large mass of the W+, W-, and Z0 particles was a problem for theorists; how to explain such large mass. The conclusion was a field that acted like molasses, slowing down the particles and giving them apparent mass. This field is generated by something called a "Higgs boson." The search for this elusive particle took forty years after it was first theorized, but in the last year or so it has been found using the large accelerator at CERN in Europe.

Four Fundamental Forces
Force Strength Range (m) Particle
Strong 1 10-15
(diameter of a medium size nucleus)
gluons, π(nucleons)
Electro- magnetic 1/137 infinite photon
mass = 0
spin = 1
Weak 10-6 10-18
(0.1% of the diameter of a proton)
intermediate vector bosons
W+, W-, Z0
mass > 80 GeV
spin = 1
Gravity 6 x 10-39 infinite graviton ?
mass = 0
spin = 2

Particle Classification

There are many different particles beyond the electron, proton, and neutron that have been discovered as we’ve explored the atom. There have also been many attempts to organize these different particles and make sense of the zoo of different characteristics. When Dmitri Mendeleev developed the periodic table of the elements based on atomic number and certain repetitive characteristics of the elements, science gained great insight into the underlying atomic structure that yielded this organization.

The goal is to repeat Mendeleev's feat and learn more about the fine structure of the universe through a logical organization of these tiny and often short-lived objects. This has led to several naming conventions and families of particles that share certain characteristics. It is hard to discuss these particles without applying these various family names, so here’s a brief discussion of the most important names with some hints at why these certain particles are grouped together.


Corresponding to most kinds of particles, there is an associated antiparticle with the same mass and opposite charge. For example, the antiparticle of the electron is the positively charged anti-electron, or positron, which is produced naturally in certain types of radioactive decay.

Particle-antiparticle pairs can annihilate each other, producing photons. Since the charges of the particle and antiparticle are opposite, total charge is conserved. For example, the positrons produced in natural radioactive decay quickly annihilate themselves with electrons, producing pairs of gamma rays.

Antiparticles are produced naturally in beta decay, and in the interaction of cosmic rays in the Earth's atmosphere. Because charge is conserved, it is not possible to create an antiparticle without either destroying a particle of the same charge (such as occurs in beta decay) or creating a particle of the opposite charge. The latter is seen in many processes in which both a particle and its antiparticle are created simultaneously (this occurs inside of particle accelerators). This is the inverse of the particle-antiparticle annihilation process.

Although particles and their antiparticles have opposite charges, electrically neutral particles need not be identical to their antiparticles. The neutron, for example, is made out of quarks, the anti-neutron from anti-quarks, and they are distinguishable from one another because neutrons and anti-neutrons annihilate each other upon contact. However, other neutral particles are their own antiparticles, such as photons, the hypothetical gravitons, and some “weakly interacting massive particles” or “WIMPs.”


Bosons comprise one of two main classes of elementary particles, the other being fermions. The name "boson" was coined by Paul Dirac to commemorate the contribution of Satyendra Nath Bose in developing, with Einstein, Bose–Einstein statistics — which theorizes the characteristics of elementary particles. Examples of bosons include fundamental particles: Higgs boson, the four force-carrying gauge bosons of the Standard Model, and the still-theoretical graviton of quantum gravity; as well as composite particles such as mesons and stable nuclei with even mass number like deuterium (hydrogen-2 or “heavy hydrogen”) and helium-4 and others.

An important characteristic of bosons is that there is no limit to the number that can occupy the same quantum state. This property is evidenced, among other areas, in helium-4 when it is cooled to become a superfluid. In contrast, two fermions cannot occupy the same quantum space. Whereas fermions make up matter, bosons, which are "force carriers" function as the “glue” that holds matter together.


A fermion (a name coined by Paul Dirac from the surname of Enrico Fermi) is any particle characterized by Fermi–Dirac statistics and following the Pauli exclusion principle.

The Pauli exclusion principle is the quantum mechanical principle that no two identical fermions may occupy the same quantum state simultaneously. The principle was formulated by Austrian physicist Wolfgang Pauli in 1925.

Fermions include all quarks and leptons, as well as any composite particle made of an odd number of these, such as all baryons and many atoms and nuclei. A fermion can be an elementary particle, such as the electron; or it can be a composite particle, such as the proton.


A subset of the fermions is leptons. A lepton is an elementary particle which does not undergo strong interactions, but is subject to the Pauli exclusion principle. The best known of all leptons is the electron which governs nearly all of chemistry as it is found in all atoms and is directly tied to all chemical properties.

Two main classes of leptons exist: charged leptons (also known as the electron-like leptons), and neutral leptons (better known as neutrinos). Charged leptons can combine with other particles to form various composite objects such as atoms, while neutrinos rarely interact with anything, and are consequently rarely observed. Although predicted in 1930 by Pauli, they were not detected until the 1950s.


Particles that interact by the strong interaction are called hadrons. This general classification includes mesons and baryons but specifically excludes leptons, which do not interact by the strong force. (Mesons are bosons, while the baryons are fermions.) The weak interaction acts on both hadrons and leptons. Both protons and neutrons are baryons, and therefore, hadrons; but the electron is a lepton.

Hadrons are viewed as being composed of quarks, either as quark-antiquark pairs (mesons) or as three quarks (baryons). There is much more to the picture than this, however, because the constituent quarks are surrounded by a cloud of gluons, the exchange particles for the color force. More on that in a later chapter.


Wolfgang Ernst Pauli was an Austrian theoretical physicist and one of the pioneers of quantum physics. In 1945, after being nominated by Albert Einstein, he received the Nobel Prize in Physics for his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or Pauli principle." The principle involves spin theory and angular momentum of atomic particles, underpinning the structure of matter and the whole of chemistry.

He was born in Vienna to a chemist, Wolfgang Joseph Pauli, and his wife Bertha Camilla Schütz in 1900. His middle name was given in honor of his godfather, physicist Ernst Mach.

Pauli spent a year at the University of Göttingen as the assistant to Max Born, and the following year at the Institute for Theoretical Physics in Copenhagen, which later became the Niels Bohr Institute. From 1923 to 1928, he was a lecturer at the University of Hamburg.

The German annexation of Austria in 1938 made him a German national, which became a difficulty with the outbreak of World War II in 1939. In 1940 he tried, in vain, to obtain Swiss citizenship, which would have allowed him to remain at the ETH. Pauli moved to the United States in 1940, where he was Professor of Theoretical Physics at the Institute for Advanced Study at Princeton. After the war, in 1946, he became a naturalized citizen of the United States, before returning to Zurich, where he mostly remained for the rest of his life. In 1949 he finally gained Swiss citizenship as well.

In 1958, Pauli was awarded the Max Planck medal. In that same year, he fell ill with pancreatic cancer. When his last assistant, Charles Enz, visited him at the Rotkreuz hospital in Zurich, Pauli asked him: “Did you see the room number?” It was number 137. Throughout his life, Pauli had been preoccupied with the question of why the fine structure constant (α), a dimensionless fundamental constant, has a value nearly equal to 1/137. Pauli died in that room on December 15, 1958.


Next chapter will discuss quarks in some length. These particles are the components of protons and neutrons and appear in other combinations. The study of quarks has added color, charm, and strangeness to an already colorful, charming, yet strange history of science.

Tuesday, May 7, 2013

History of Science -- Part Twenty-Two: The Weak Nuclear Force

Enrico Fermi
We learned in the last chapter that neither protons nor neutrons are fundamental particles. That is, they are made up of something even more basic: quarks. Both nucleons are made of a combination of three quarks, but the recipe is different. Protons are sort of like cake and neutrons are like pie. Similar ... both for dessert ... but different things in the mix.

There are several implications of these different recipes. For one thing, protons have a positive charge while neutrons are electrically neutral. Also, neutrons are just a little bit more massive than protons. But there is another difference. Protons are fundamentally stable, while neutrons are prone to disintegrate or fly apart.

Neutrons can decay, turning into a proton and ejecting an electron is what is called “beta radioactivity.” The force that destroys a neutron is the “weak force,” so called because it appears weak by comparison to the electromagnetic and the strong force at normal temperatures. The weak force disrupts neutrons and protons, causing the nucleus of one atomic element to transmute into another through beta radioactivity. It plays an important role in helping convert the protons — the seeds of the hydrogen fuel of the Sun — into helium. This is the process by which energy is released, eventually emerging as sunshine.

I stated earlier that gravity was too weak to be felt at the atomic level. That is not true when there is a massive amount of atoms, such as in a large planet or sun. The effect on gaseous atoms in large bodies like the sun is to pull the atoms together under tremendous pressure driven by gravity. This closeness causes a large amount of bumping and banging, atomic motion that we call “heat.” So the pressure builds up the heat to a point that the electrons are stripped off leaving bare nuclei. This is a fourth state of matter called a “plasma.” (The other three states are solid, liquid, and gas.)

This is what the core of our Sun and other suns similar to ours is like. It is a big ball of hydrogen gas under great pressure producing heat and making an atomic plasma. This plasma then undergoes fusion, converting hydrogen to helium and creating a lot of energy.

Not only is energy produced, but in some stars, other elements are created such as carbon, oxygen, and iron, all the way up to the highly radioactive elements such as uranium and plutonium. When these stars explode, they spread these heavier elements out throughout the galaxy. That is the basic mechanism whereby the original element of hydrogen produced in the “big bang” becomes the heavier elements we find on the earth and in our bodies. That’s right! We are made up of atoms from exploding stars. We are literally star stuff!!

Here are the details. Interesting that they involve all four of the known forces of nature. That is what keeps us in existence, an intricate dance of the forces of Nature. There are many theories that if these various physical constants such as the weak and the strong force were slightly different, then the universe and life could not exist. A lucky accident? I don’t think so!

The gravitational attractions among the multitudinous protons in the Sun pull them inwards until they are nearly touching. Occasionally two move fast enough to overcome their electrical repulsion momentarily, and they bump into one another. The weak force transmutes a proton into a neutron, the strong force then clumps these neutrons with the protons, after which they build up a nuclei of helium.

Energy is released and radiated courtesy of the electromagnetic force. It is the presence of these four forces and their different characteristics and strengths that keeps the Sun burning at just the right rate for us to be here.

In the Standard Model of particle physics the weak interaction is theorized as being caused by the exchange (that is, emission or absorption) of W and Z bosons; and as such, is considered to be a non-contact force, like the other three forces. The best known effect of this emission is beta decay, a form of radioactivity. The Z and W bosons are much heavier than protons or neutrons and it is the heaviness that accounts for the very short range of the weak interaction.

Since the mass of the Z and W particles is on the order of 80 GeV, the uncertainty principle dictates a range of about 10-18 meters which is about 0.1% of the diameter of a proton. It is the search for the mechanism that creates these heavy particles that points to the existence of the Higgs boson that was experimentally demonstrated just in the last year.

The discovery of the W and Z particles in 1983 was hailed as a confirmation of the theories which connect the weak force to the electromagnetic force in electro-weak unification. The theory suggests that at very high temperatures, where the equilibrium kinetic energies are in excess of 100 GeV, these particles are essentially identical and the weak and electromagnetic interactions are manifestations of a single force.

The weak force was originally described, in the 1930s, by Fermi's theory of a contact four-fermion interaction: which is to say, a force with no range (entirely dependent on physical contact.) However, it is now best described as a field, having range, albeit a very short range. The theory of the weak interaction can be called Quantum Flavordynamics (QFD), in analogy with the terms QCD and QED, but in practice the term is rarely used because the weak force is best understood in terms of electro-weak theory.

Enrico Fermi, born in 1901, was an Italian theoretical and experimental physicist, best known for his work on the development of Chicago Pile-1, the first nuclear reactor, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics.

Along with Robert Oppenheimer, he is referred to as "the father of the atomic bomb.” He held several patents related to the use of nuclear power, and was awarded the 1938 Nobel Prize in Physics for his work on induced radioactivity and the discovery of transuranic elements. Throughout his life Fermi was widely regarded as one of the very few physicists who excelled both theoretically and experimentally.

Fermi left Italy in 1938 to escape racial laws that affected his Jewish wife Laura, and emigrated to the United States, where he worked on the Manhattan Project during World War II. Fermi led the team that designed and built the Chicago Pile-1, and initiated the first artificial self-sustaining nuclear chain reaction when it went operational in December 1942. He was present at the Trinity test on July 16, 1945, where he used one of his experiments to estimate the bomb's yield.

His estimate of the strength of the atomic bomb detonated at the Trinity test, based on the distance traveled by pieces of paper dropped from his hand during the blast, was 10 kilotons of TNT. This was remarkably close to the now-accepted value of around 20 kilotons, a difference of less than one order of magnitude, and all based on a simple experiment.

Enrico Fermi was born in Rome, the third child of Alberto Fermi, a division head in the Ministry of Railways, and Ida de Gattis, an elementary school teacher. As a young boy, he shared his interests with his brother Giulio. They built electric motors and played with electrical and mechanical toys. He was largely self taught working his way through several very difficult and advanced science texts.

Fermi graduated from high school in 1918 and applied to the Scuola Normale Superiore in Pisa. The school provided free lodging for students but candidates had to take a difficult entrance exam, which included an essay. The given theme was "Specific characteristics of Sounds." The 17-year-old Fermi chose to derive and solve the partial differential equation for a vibrating rod, applying Fourier analysis. The examiner that interviewed Fermi concluded that his entry would have been commendable even for a doctoral degree. Fermi achieved first place in the classification of the entrance exam.

During his years at the Scuola Normale Superiore, Fermi's knowledge of quantum physics reached such a high level that his professor asked him to organize seminars on the topic. During this time Fermi learned tensor calculus, a mathematical technique that was needed to demonstrate the principles of general relativity. Fermi initially chose mathematics as his major, but soon switched to physics. He remained largely self-taught, studying general relativity, quantum mechanics, and atomic physics

Fermi was the first to warn military leaders about the potential impact of nuclear energy, giving a lecture on the subject at the Navy Department in March 1939. In August 1939, three Hungarian physicists — Leó Szilárd, Eugene Wigner, and Edward Teller — prepared the “Einstein-Szilárd letter,” which they persuaded Einstein to sign because of his reputation, warning President Franklin D. Roosevelt of the probability that the Nazis were planning to build an atomic bomb.

Eventually, the first artificial nuclear reactor, Chicago Pile-1, was constructed at the University of Chicago, by a team led by Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on December 2, 1942 at 3:25 PM. The reactor support structure was made of wood, which supported a pile (hence the name) of graphite blocks, embedded in which was natural uranium-oxide “pseudospheres” or “briquettes.”

This experiment was a landmark in the quest for energy, and it was typical of Fermi's approach. Every step was carefully planned, every calculation meticulously done. Thus the first self-sustained nuclear chain reaction was achieved.

In the summer of 1944, Robert Oppenheimer persuaded Fermi to join his “Project Y” in Los Alamos, New Mexico. Arriving in September, Fermi was appointed an associate director of the laboratory, with broad responsibility for nuclear and theoretical physics, and was placed in charge of “F Division,” which was named after him.

After the war, Fermi served on the General Advisory Committee of the Atomic Energy Commission, a scientific committee chaired by Robert Oppenheimer that advised the commission on nuclear matters and policy.

Following the detonation of the first Soviet fission bomb in August 1949, Fermi, along with Isidor Rabi, wrote a strongly worded report for the committee, opposing the development of a hydrogen bomb on moral and technical grounds. Although Fermi was later proven wrong on the technical objections, the moral issues are still present in today’s world.

Also still present is our distrust of those that object to progress. Fermi was among the scientists who testified on Oppenheimer's behalf at the Oppenheimer security hearing in 1954 that resulted in denial of Oppenheimer's security clearance.

The hearing was a product of longstanding doubts about Oppenheimer's loyalty, and suspicions that he was a member of the Communist Party and might even have spied for the Soviet Union. The concerns about him were exacerbated by personal conflicts between Oppenheimer and others in the atomic community, including Lewis Strauss, chairman of the Atomic Energy Commission, and Edward Teller, with whom he had clashed over the development of the hydrogen bomb.

Oppenheimer was born in New York City in 1904, son of Julius Oppenheimer, a wealthy Jewish textile importer who had immigrated to the United States from Germany in 1888, and Ella Friedman, a painter. He had studied in England and he applied to the Cavendish Laboratory with Ernest Rutherford, although Rutherford considered him more of a theorist than an experimentalist, Oppenheimer was accepted to the laboratory by J.J. Thomson.

His German ancestry should not have been an issue since, by the time of Oppenheimer’s trial, the war with Germany was over and they were considered our national allies. However, our former war ally, Russia or the USSR, was now our cold war enemy. Just how much national origin or even ethnic and religious background played in the drama is not certain. These were very troubling times in the U.S.: suspicion and prejudice was prevalent.

The official result was that “Oppenheimer was unusually discrete with atomic secrets, yet he was a security risk” and his clearance was withdrawn and he never worked for the government again. The father of the atomic bomb was found to be a security risk. Government … don’t you just love it?

Oppenheimer's hearing is the subject of a play, and several article and book-length studies. Oppenheimer's trial, which marked the end of his formal relationship with the government of the United States, generated considerable controversy regarding whether the treatment of Oppenheimer was fair, or an expression of anti-Communist hysteria.

Fermi died in 1954 and Oppenheimer in 1967, but theoretical work on the weak interaction continues. In 1968, the electromagnetic force and the weak interaction were unified, when they were shown to be two aspects of a single force, now termed the electro-weak force. The hope is to, someday, combine all four forces into a unified field theory. That may be far off in the future, but small steps are made each day.

The discovery of quarks and the concept of even more mysterious forces beyond them means that, unlike the pronouncement of Lord Kelvin at the turn of the last century, there is plenty more exciting discoveries to be made. We’ll start that discussion in the next chapter.

History of Science -- Part Twenty-One: The Strong Nuclear Force

Hideki Yukawa
The attraction of the positive charged nucleus holds the negative electrons in their paths around the atom, similar to how the gravitational attraction of the sun holds the earth in its orbit.

However, the repulsion of the “like” charges in the nucleus creates a paradox of the existence of the nucleus itself. What holds it together? The nucleus is compact. Its positive electrical charge due to the many protons within it should cause it to fly apart. How can these protons, experiencing such intense electrical repulsion, manage to congregate? Why doesn’t the nucleus self-destruct?

The fact that it doesn’t gives an immediate clue to the existence of an additional, “strong” attractive force felt by the protons and the neutrons, which is powerful enough to hold them in place and resist the electrical repulsion. This strong force is one of a pair that act in and around the atomic nucleus. They are short range forces that just work on the nuclear scale and are not immediately familiar to our gross senses, yet they are essential to our existence. The strong force is so named since it is stronger than the electric force (and much, much stronger than gravity which is non-consequential at the atomic scale).

The nuclear force has been at the heart of nuclear physics ever since the field was born in 1932 with the discovery of the neutron by James Chadwick. The traditional goal of nuclear physics is to understand the properties of atomic nuclei in terms of the “bare” interaction between pairs of nucleons, or nucleon–nucleon force.

The strong force is 137 times stronger than the electric force. This number, “137,” appears in many quantum formulas and is called “alpha” or "α." Alpha is another physical constant of the universe such as “c,” the speed of light, or Planck’s constant.

For thousands of years we were only aware of the two forces, gravity and electromagnetic, until the “atomic age” increased our understanding of these two additional forces so well hidden away in the nucleus of the atom. Even in 2013, we are still making important and fundamental discoveries about these forces, although the latest experiments are actually based on theories put forward during the 1960’s.

The stability of the nuclei of atomic elements can be a delicate balance between the competing strong attraction and the electrical repulsion. You cannot put too many protons together or the electrical disruption will make the nucleus unstable. This is the source of certain radioactive decays, where the nucleus will split into smaller fragments. All of the elements with 84 or more protons are radioactive and there are a couple of naturally radioactive elements with less: technetium with 43 protons and promethium with 61.

Neutrons and protons feel the strong force equally; however, only the protons feel the electrical repulsion. This is why the nuclei of all elements other than hydrogen contain not just protons, but have neutrons to add to the strong attractive stability of the whole.

Uranium-235, for example, is so called due to the 92 protons that make it the uranium element and 143 neutrons making a total of 235 nucleons in all.

Actually, too many neutrons seems to lead to instability too. The extra mass of a neutron relative to the proton (recall the neutron is a small amount more massive than the proton) underlies an intrinsic instability of neutrons, whereby they can decay, turning into protons and ejecting an electron — the so-called “beta” particle of “beta rays.”

In 1934, Hideki Yukawa made the earliest attempt to explain the nature of the nuclear force. According to his theory, massive bosons (mesons) mediate the interaction between two nucleons. Although, in light of modern quark theory (QCD), meson theory is no longer perceived as fundamental, the meson-exchange concept continues to represent the best working model for a quantitative nucleon force potential.

Hideki Yukawa was born in Tokyo, Japan, and grew up in Kyoto. In 1929, after receiving his degree from Kyoto Imperial University, he stayed on as a lecturer for four years. After graduation, he was interested in theoretical physics, particularly in the theory of elementary particles. In 1933 he became an assistant professor at Osaka University, at the age of only 26.

In 1935 he published his theory of mesons, which explained the interaction between protons and neutrons, and was a major influence on research into elementary particles. In 1940 he became a professor in Kyoto University and he won the Imperial Prize of the Japan Academy, and in 1943 the Decoration of Cultural Merit from the Japanese government. In 1949 he became a professor at Columbia University, the same year he received the Nobel Prize in Physics, after the discovery by Powell, Occhialini, and Lattes of Yukawa's predicted pion in 1947. He was the first Japanese Nobel Laureate. Yukawa also worked on the theory of K-capture, in which a low energy electron is absorbed by the nucleus.

In ordinary matter, the strong force acts only in the nucleus and, at its source, we now think it is due to the presence of quarks, the ultimate basic particle from which protons and neutrons are formed. (Protons and neutrons, each contain three quarks.)

It was discovered in the 1970’s that protons and neutrons were not fundamental particles, but were made up of constituent particles called quarks. The strong attraction between nucleons was the side-effect of a more fundamental force that bound the quarks together inside the protons and neutrons.

As the electric and magnetic forces are effects arising from electric charges, so is the strong force ultimately due to a new variety of charge, which is carried by quarks, but not by leptons such as the electron. Hence electrons are not affected by the strong force at all.

Thus the strong nuclear force (or actually the “residual strong force”) binds the nucleus together. There is energy in this bonding which is released when large atoms are split or when small atoms such as hydrogen are fused. This is the energy released in nuclear power and nuclear weapons, although fusion, the process that takes place in the sun, has only been used for weapons. If fusion power could be developed, that would be a great advancement due to the lack of radioactive by-products.

The force is powerfully attractive between nucleons at distances of about 1 femtometer (fm) between particle centers, but rapidly decreases to insignificance at distances beyond about 2.5 fm. (A femtometer is 10-15 meters or 10-13 cm.) That is about the diameter of a medium sized nucleus. Again, this limited range is why the larger atoms are not stable and are radioactive.

At very short distances, less than 0.7 fm, the force becomes repulsive, and is responsible for the physical size of nuclei, since the nucleons can come no closer than the force allows.

The nuclear force is now understood as a residual effect of the even more powerful strong force, or strong interaction, which is the attractive force that binds particles called quarks together to form the nucleons themselves. This more powerful force is mediated by particles called gluons. A gluon is a type of gauge boson. Gluons hold quarks together with a force like that of electric charge, but of far greater power.

I’ve got more to say about quarks and this new kind of charge and a theory called Quantum Chromodynamics. So there’s more to cover from QCD to the weak force and radioactivity. That’s next.