History of Science -- Part Twenty: Anatomy of an Atom

We now understand the three basic particles that make up the atom. There’s the electrons in orbit around a tiny yet massive nucleus made up of protons and neutrons, collectively called nucleons. The electrons each carry a charge of minus one and the protons balance that out with their individual charge of plus one. The Neutrons are electrically neutral and carry no charge.

The number of protons determines the type of element the atom is. For example, one proton is hydrogen and two protons is helium. In the middle of the table of elements is iron with 26 and lead with 82, while the very large atoms such as plutonium have 94 protons.

Typically, the number of electrons matches the number of protons, and the electric charge of the atom is balanced, although there can be local electric effects. It is also possible for an atom to lose or gain an electron or two giving the atom a net electric charge and these are called ions.

There are usually about the same number of neutrons in the nucleus as there are protons, but the number can vary slightly. The overall mass of the atom is given by the number of nucleons since the electrons add very little to the overall mass. Although the mass of an atom does affect the overall weight or interaction with gravity, that is a macro effect depending on the billions and billions of atoms in an object of “human” size.

Besides the atoms and molecules and substances they make up, the weight is also affected by the organization of the atoms and their spacing. More important at the atomic level, mass has an impact on inertia and momentum. Since the heavier elements are fifty to one hundred times as massive as hydrogen, the larger elements such as iron and lead tend to weight more in large quantities than smaller elements such as hydrogen or carbon.

Isotopes are variants of a particular chemical element. While all isotopes of a given element share the same number of protons and electrons, each isotope differs from the others in its number of neutrons. For example there is carbon-12, carbon-13, and carbon-14, each with a different number of neutrons. Isotopes are indicated by the number counting the total protons and neutrons.

Carbon has 6 protons, and it commonly occurs with 6, 7, or even 8 neutrons. These different forms of the element differ greatly by the their total mass since neutrons are just a little more massive than protons. More significantly, these different isotopes vary in their nuclear stability. Some isotopes are stable, while others are prone to spontaneous decay. That’s a great hint of what is holding the nucleus together and this instability is what gives us radioactivity and also nuclear power and bombs.

The size of an atom is difficult to describe because atoms have no definite outer boundary. To overcome this problem, the size of an atom is estimated by describing its radius. In metals, this is done by measuring the distance between two nuclei in the solid state and dividing this distance by 2. For nonmetallic elements, that exist in pure form as molecules, measurements can be made of the distance between nuclei for two atoms covalently bonded together. The size of a typical atom is on the order of 10^-8cm. Atoms can be viewed with modern instruments and IBM Research has even produced a recent movie where they created an animated story line by moving and photographing atoms.

The nucleus, on the other hand, is very small and located in the center of the structure. The compact nucleus is between about 2 and 15 x 10^-12 cm. That means that the nucleus is between ten to one hundred thousandths the size of the overall atom. Atoms are mostly just empty space with a hard and massive core at the center. If an atom was blown up to the size of a large living room, the nucleus would only be about the size of a spec of dust … mostly empty space for sure.

The size of the actual particles echoes this in reverse with electrons very small while protons and neutrons are much larger particles.

The mass given in the table is the “rest” mass, since relativity states that energy and mass are interchangeable (times c²), so accelerated particles have additional mass. For the same reason, mass of particles is often given in electron-volts which is a measure of energy. (For “atomic mass units” or “amu” we assume that the neutron is exactly 1.)

(Again, although a large collection of atoms such as a rock or a mountain or a planet are affected by gravity, the tiny atoms are not affected by gravity because the electrical force and other forces in the atom are much, much more powerful. You ignore gravity when calculating for atoms.)

Name	Symbol	Mass (g)	Mass (amu)	Size
Proton	P+	1.6726231 x 10-24	0.99862349	10-13 cm
Neutron	n0	1.6749286 x 10-24	1	10-13 cm
Electron	e-	9.1093897 x 10-28	0.000543867	< 10-15

Notice from the table that the mass of the proton is 99.86% the mass of the neutron and the electron is 0.054% the mass of the neutron.

Recall that, before neutrons were discovered, scientists thought that the neutral particles in the nucleus were atoms of hydrogen: a single proton with a single electron in orbit. Notice that you can’t really tell by the mass, although the mass of a neutron is slightly more than the mass of a proton plus the mass of an electron. Before the neutron was discovered, the measurement of these particle masses was not as accurate, so that did not disprove the “nuclear electrons” theory. It was quantum formulas that first indicated electrons can’t be contained in the nucleus, even if they are attracted by the positive charge of the proton. Trapping an electron in such a small space wold require a tremendous amount of energy — much more energy than is in the atom.

As you can calculate from the table, it takes nearly 2,000 electrons to equal the mass of a single nucleon. Also, electrons are very small compared to neutrons and protons. The actual diameter of an electron has never been measured and some consider it may be a mathematical “point,” although that would imply an infinite electric field at that point.

As we will soon learn, the electron is an elementary particle and can’t be broken down, while the neutron and the proton are actually made up of more elementary particles called “quarks.” Both the nucleons are made of a combination of three quarks, but there are different kinds of quarks.

It is possible to make a comparison between our solar system and an atom. You can compare the nucleus to the sun and the electron orbits to the orbits of the planets. However, there are significant differences. For example, the planets in the solar system are primarily in a single plane, while atoms are more “three dimensional.” Also, the electron orbits are not defined by Kepler’s laws, but rather by Bohr’s description using Planck’s constant. Of course, we learned that, in quantum theory, the actual location of the electrons in the orbit is a probabilistic wave that sort of indicates the electrons are simultaneously “everywhere” at once.

But those differences aside, it is true that the atom, like the solar system, is mostly empty space. Although the concentration of mass in an atom is much more intense than the concentration of mass in the sun, you can visualize the large central object of the solar system to be like the nucleus.

So that’s what an atom looks like. I mentioned that modern instruments, analogous to a microscope, have directly observed atoms. However, the “magnification” required to see the nucleus is beyond our current technology. Instead, we “observe” the nucleus and the nucleons using indirect methods. We fire particles at atoms in “atom smashers” called “particle accelerators” and determine facts by observing what particles fly out of the rare collisions. (Since atoms are mostly empty space, we rarely strike the nucleus when we fire particles, so we have to fire a lot in order to get results.)

The energy of the particles being fired determines the resolution or “magnification” capability. Modern accelerators can resolve the nucleus and the protons and neutrons. Getting deeper into the particles and observing the quarks and other related particles is the current state of the art. Our theories extend even deeper to the components of quarks and similar particles which is the realm of modern “string theory,” but we have yet to explore that deep into atoms with our current experimental technology.

Since string theory is the very frontier of science, we won’t address it. We will discuss quarks as we search for the force that holds the nucleus together … next time.

The History of Science -- Part Twenty-One

History of Science -- Part Nineteen: Neutrons

James Chadwick

The hydrogen atom is very unique. Since it is the simplest atom with only one proton and one electron (and typically no neutrons) it didn’t present the problem that the atoms of the other elements did. Namely, what holds together a group of protons whose like positive charges should repel them and force the nucleus to fly apart.

We now know that the next larger atom, helium, with its two protons and two electrons also has two neutral particles in its nucleus called "neutrons." These neutrons are essential in establishing a new force of nature, now called the “strong nuclear force,” and it is this new force that overcomes the electric force’s repulsion to hold the nucleus tightly together.

While it was easier to discover electrons since they are on the “outside” of the atom and can be freed relatively easy to be studied with devices like the Crookes tube, getting inside the nucleus was another matter. A hydrogen atom stripped of its electron gave access to the proton, and the helium atom stripped of its two electrons exposes a nucleus consisting of two each of protons and neutrons. Still, the lack of an electric charge made the neutrons difficult to detect.

The early study of these stripped atoms were thought of as “rays.” Some of the first discoveries involved radioactivity, the breakdown of the nucleus of very large atoms and how these “rays” affected photographic film.

There were three types of radiation identified by these researchers:

1. Alpha rays are are fast moving helium atoms. They have high energy, typically in the MeV range, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper.

   An electron-volt or eV is a measure of energy, a very small measure. It is appropriate for use at the atomic scale because it is defined as the kinetic energy (energy of motion) gained (or lost) by a single electron when accelerated across an electric potential of one volt.

   This is analogous to the kinetic energy gained by a rock falling in a gravitational field. A single electron volt is 1.6 x 10^-19 joule where a joule is the amount of energy (or power) required to produce one watt of power for one second — not a very large lightbulb at all. So, if joule’s are small, eV are teeny-tiny. But this is the atomic scale, after all, and there are billions and billions of atoms, so it can add up.

   An MeV is a mega-electron-volt or one million electron volts … still a tiny amount of energy on a human scale.

2. Beta rays are fast moving electrons. They typically have energies in the range of a few hundred keV to several MeV. Since electrons are much lighter than helium atoms, they are able to penetrate further, through several feet of air, or several millimeters of plastic or less of very light metals.

3. Finally, Gamma rays are photons, just like light, except of much higher energy, typically from several keV to several MeV. X-Rays and gamma rays are really the same thing, the difference is how they were produced. Depending on their energy, they can be stopped by a thin piece of aluminum foil, or they can penetrate several inches of lead.

These rays were known prior to the “quantum age.”

In addition to a lack of understanding of what force held the nucleus of larger atoms together, there was another concern that bothered scientists about the nucleus. That was the difference between the mass of the simple hydrogen nucleus, which they figured was the mass of a single proton, and the mass of higher elements. For example, helium, which should contain two protons, had a nucleus that was about four times as massive as the hydrogen nucleus. This disparity in mass was apparent in all the elements.

In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. The periodic chart of the elements, an important tool for understanding atoms as well as chemical and physical properties, is based on the atomic number.

In 1920, Ernest Rutherford conceived the possible existence of the neutron. In particular, Rutherford considered that the difference found between the atomic number of an atom and its atomic mass could be explained by the existence of a neutrally charged particle within the atomic nucleus. He considered the neutron to be a neutral double consisting of an electron orbiting a proton.

This seemed to make sense because we now know the neutron is just slightly heavier than the proton and the electron is a very small particle with less than one-thousandth the mass of the either nucleons — the term for protons and neutrons. Through the 1920s, physicists had generally accepted an (incorrect) model of the atomic nucleus as composed of protons and electrons. It was known that atomic nuclei usually had about half as many positive charges than if they were composed completely of protons, and in existing models this was often explained by proposing that nuclei also contained some "nuclear electrons" to neutralize the excess charge. Thus, the nitrogen-14 nucleus would be composed of 14 protons and 7 electrons to give it a charge of +7 but a mass of 14 atomic mass units.

However, the new quantum mechanics implied that a particle as light as the electron could not be contained in a region as small as the nucleus with any reasonable energy. In 1930, Viktor Ambartsumian and Dmitri Ivanenko in the USSR found that, contrary to the prevailing opinion of the time, the nucleus cannot consist of protons and electrons. They proved that some neutral particles must be present besides the protons.

In 1931, Walter Bothe and Herbert Becker in Germany found that if the very energetic alpha particles emitted from polonium fell on certain light elements, specifically beryllium, boron, or lithium, an unusually penetrating radiation was produced. At first this radiation was thought to be gamma radiation, although it was more penetrating than any gamma rays known, and the details of experimental results were very difficult to interpret on this basis.

The next important contribution was reported in 1932 by Irène Joliot-Curie (Madame Curie) and Frédéric Joliot in Paris. They showed that if this unknown radiation fell on paraffin, or any other hydrogen-containing compound, it ejected protons of very high energy. This was not in itself inconsistent with the assumed gamma ray nature of the new radiation, but detailed quantitative analysis of the data became increasingly difficult to reconcile with such a conclusion.

Finally, in 1932, James Chadwick performed a series of experiments at the University of Cambridge, showing that the gamma ray hypothesis was untenable. He suggested that the new radiation consisted of uncharged particles of approximately the mass of the proton, and he performed a series of experiments verifying his suggestion. These uncharged particles were called neutrons, from the Latin root for "neutral" and the Greek ending "-on" (such as the names of the electron and proton).

James Chadwick was a Physicist by profession. He was born in 1891 in Manchester, England. Chadwick got admitted in Victoria University, Manchester. He was more interested in studying mathematics but instead he was admitted in the field of physics mistakenly. Chadwick was pretty bashful, so he did not make any attempt to amend the error. In 1911, he graduated from the Honors School of Physics. He continued his studies at the same school in the laboratory of Ernest Rutherford.

Now with the discovery and confirmation of the existence of neutrons, the model of the atom was complete. Atoms in their normal state consist of a nucleus containing protons providing a positive charge and neutrons with no electric charge. This nucleus is surrounded by a cloud of electrons. Normally the number of electrons with their negative charge and the number of protons are equal. If an atom gains or loses an electron or two, it becomes an “ion,” a charged atom. Positive ions have lost electrons and negative ions have gained electrons.

That seemed a good and simple model and worked well for chemistry and electrical devices until science looked closer. Again radiation from large atoms provided some clues as did the powerful “rays” from space called cosmic rays provide others. Soon scientists realized that these three basic particles were not all there is. The new, sub-atomic particles being discovered soon became a zoo of new and strange objects. But,before we start splitting atoms, we should discuss this strong force that could hold the nucleus together and the role that neutrons play in that force, for there is yet another nuclear force to be found … next time.

The History of Science -- Part Twenty

The Golden Age of Science Fiction

I’m a science fiction fan ... one of the biggest ... and I mean that several ways. Yet I think this is the first time I’ve written about SciFi on my blog. After over 250 different subjects and essays, I finally get around to my life-long love affair with science fiction ... which was the genesis and heart of my love of science.

I was around ten-years-old when I read my first science novel. It was “Have Space Suit, Will Travel” by Robert Heinlein. This was a story (or book) intended for a younger audience ... a so-called “juvenile.” Heinlein wrote this book after world war two and it was based on his experience as an aeronautics engineer working at a lab where pressure suites were being developed for use at high altitudes. The title echoes the expression “Have tux, will travel” and also the popular at that time TV show “Have Gun — Will Travel.”

Although the book was written for kids, it did receive a nomination for the Hugo award in 1959. The Hugo Awards are a set of awards given annually for the best science fiction or fantasy works. The awards are named after Hugo Gernsback, the founder of the pioneering science fiction magazine Amazing Stories. There may be a movie in the works now based on that this story.

I’ve read science fiction all my life. I finished off a couple of short stories just last night. In fact, although modern science fiction is often in the novel form, in its hay-day it was most often short stories published in magazines called “pulps” due to the inexpensive paper that was used. With our modern world of computers and cellphones and blockbuster SciFi movies such as “2001: A Space Odyssey” and “Star Wars” as well as lots of TV shows with an outer space theme, we seem to be living the fiction.

If you go back one hundred years, it was also a time of speculative fiction, but the evidence of the modern technological world was just starting to appear. The nineteenth century saw steam and the telegraph both drastically reduce distances and inspiring imaginations. There were some founding science fiction in the writings of Jules Verne and H.G. Wells during that time, but with the advent of the twentieth century there was a revolution, both in science and in day-to-day life. The new century saw the spread of the automobile, electric light, telephone, radio, and many other new inventions that definitely pointed to a technological future.

Fiction was filled with stories of spaceships and aliens and the imagination of a generation was captured by these low cost, “pulp” publications and what dreams were dreamed.

The development of American science fiction as a self-conscious genre dates in part from 1926, when Hugo Gernsback founded Amazing Stories magazine, which was devoted exclusively to science fiction tales. He is notable for having chosen the variant term “scientifiction” to describe this incipient genre. The term "scientifiction" and Gernsback’s name are often inextricably linked. However, even though Gernsback encouraged stories featuring scientific realism to educate his readers about scientific principles, such stories shared the pages with other exciting tales that had little basis in reality.

Published in his and other pulp magazines with great and growing success, such scientifiction stories were not viewed as serious literature but as sensationalism. Nevertheless, a magazine devoted entirely to science fiction was a great boost to the public awareness of the scientific speculation story. Amazing Stories competed with several other pulp magazines, including Weird Tales (which primarily published fantasy stories), Astounding Stories, and Wonder Stories, throughout the 1930s. It was in the Gernsback era that science fiction fandom arose through the medium of the “Letters to the Editor” columns of Amazing and its competitors.

At this time science fiction was still a relatively small field dominated by Gernsback and other editors such as F. Orlin Tremaine. Probably the most notable work that came from this period was the writings of E.E. “Doc” Smith. Edward Elmer Smith, Ph.D., was a chemical engineer who worked in the food industry on doughnut and pastry mixes. His two series, the Skylark and Lensmen earned him the title the “father of the space opera.” But it was his inclusion of hard science facts into his fiction that really was the spark.

It was in the 1930’s that science fiction found its voice. Toward the end of that decade the voice began to resemble, more and more, that of John Wood Campbell, Jr., and in the 1940’s Campbell dominated the field to the point where to many he seemed to be all of science fiction. It was his age of influence that was “The Golden Age of Science Fiction.”

Campbell’s singular, personal impact was a phenomenon that had never happened before and can never be repeated. Before the 1940’s, science fiction was a small field, there was nothing to dominate. Campbell, however, towered. He had a charismatic personality that utterly overshadowed everyone he met. He overflowed with energy and he had his way with science fiction. He found it pulp and he turned it into something that was his heart’s desire. He then made it the heart’s desire of the reader.

Put another way, he found science fiction a side-issue written by eager fans with only the beginnings of ability, or by general pulp writers who substituted spaceships for horses, and disintegration rays for revolvers, and then wrote their usual stuff. Campbell put science fiction center stage and made it a field that could be written successfully only by science fiction writers who learned their craft.

To put it still another way, he found science fiction a trifling thing that could only supply writers with occasional pin-money and he labored to make of it something that which science fiction writers could make a living. He could not, in the 1940’s, drag the field upward to the point of making writers rich, but he laid the foundations for the coming of that time in later decades.

John W. Campbell, Jr., born in Newark, N.J. in 1910, attended M.I.T. between 1928 and 1931, but never finished his schooling there. The story is that he failed German, and transferred to Duke University. In many ways this experience was reflected in his later life. At M.I.T. he picked up his interest in science, and, at Duke, he was influenced by R.B. Rhine and the ESP tests, carried out at the Parapsychology Laboratory at Duke University, and picked up his interest in extra-sensory perception and the scientific fringe. The former was apparent in the 40’s and the latter became his theme in the 50’s and 60‘s with his support of L.Ron Hubbard.

He started out as a writer and sold his first science fiction story when he was just a teenager, which is not unusual for science fiction devotees. However, he didn’t realize you need to keep a carbon copy and the manuscript was lost by the publisher he submitted it to, which was unusual. So having a good backup isn’t just an issue in our computer age. His second sale was “When Atoms Fail,” which appeared in the January 1930 issue of Amazing. He was nineteen at the time.

As I mentioned, in those days the greatest name among the science fiction writers was E.E. “Doc” Smith. His “The Skylark of Space,” a three-part serial that appeared in Amazing in 1928 dealt with interstellar travel and mega-forces and mega-distances. It was an example of what came to be called “super-science stories” and Smith made it his specialty. Campbell followed that model from the start.

There was a difference, however. Smith could not change. He remained super-science to the end. Campbell could change and did. He wanted to write science fiction less in scale and more with puzzling mind.

He even changed his name for that purpose, using the pseudonym Don A. Stuart. Under this new name he wrote “Twilight” which appeared in 1934 in Astounding Stories. This tale told of the end of humanity in a far distant future. It proved a tremendous hit, and instantly began the change of making science fiction smaller in scope and deeper in thought.

He wrote “Stuart” stories predominately thereafter, until he published his best known story, “Who Goes There?” that appeared in Astounding in 1938. In 1973 the story was voted by the Science Fiction Writers of America as one of the finest science fiction novellas ever written.

The story has been adapted three times as a motion picture: the first in 1951 as “The Thing from Another World;” the second in 1982 as “The Thing” directed by John Carpenter; and most recently as a prequel to the Carpenter version, also titled “The Thing," released in 2011. In the original version, six-foot, seven-inch tall James Arness, later to gain fame as Marshal Matt Dillon of Gunsmoke, played the alien, although it was difficult to recognize him in the makeup. Part of the movie was shot in Glacier National Park in Montana ... possibly a good substitute for the snowy and remote Alaska research base that was the supposed locale for the story. The later movies matched the original Campbell “shape shifter” story line more accurately than the 50’s version.

By October of 1937, Campbell was appointed to an editorial position at Astounding, and, within a few months, he was in full charge. His first significant action was to change the name of the magazine. He wanted to get rid of words like “amazing,” “astounding,” and “wonder,” which emphasized the shock-value and superficiality of science fiction. He wanted to call the magazine simply Science Fiction, thereby defining its scope clearly. Unfortunately, that name was already taken by what turned out to be a short-lived magazine from Columbia Publications. So, with its March 1938 issue, Astounding Stories became Astounding Science Fiction.

As an editor, Campbell was a phenomenon even greater than he had been as a writer. He held open house and anyone who might conceivably help him achieve his aims was welcome. It was then that an eighteen-year-old named Isaac Asimov appeared with his first story and was invited to Campbell’s office for a chat lasting over one hour. Although Campbell rejected Asimov’s first story, he saw the potential in the soon to be famous writer, and encouraged him. Although he continued to reject Asimov’s stories, he would meet with the young writer offering advice and encouragement until Asimov’s writing improved to the point of acceptance.

These were difficult times for publishing houses and writers. The war created a paper shortage and the draft and war-work depleted the number of writers. Many magazines failed. In addition, comic magazines (comics) had appeared and competed for the limited small change of the science fiction buying public. As magazines failed and were discontinued, only Astounding Science Fiction survived, largely due to the efforts of John Campbell.

Campbell had built a stable of excellent writers, some from before his time, but ones that fit the Campbellesque style and wrote what Campbell sought. Outstanding among those writers was Jack Williamson, Clifford D. Simak, and L. Sprague de Camp. However, for the most part, Campbell found new writers such as Isaac Asimov. His first issue that truly demonstrated his thinking and new authors in his mold was the July 1939 issue. Most consider it as the start of the “Golden Age of science fiction.”

The issue contained such classics as “Black Destroyer,” the first science fiction story written by A.E. van Vogt, “Trends” by Isaac Asimov, “Greater Than Gods” by C.L. Moore, and “The Moth” by Ross Rocklynne. All four of these authors became known as “Campbell authors,” although some had published before.

The next issue contained the first story by new author Robert A. Heinlein, “Life-Line.” Heinlein and van Vogt were common contributors to Astounding and soon were science fiction “superstars.” Another great Campbell author is Arthur C. Clark, whose first science fiction story “Loophole” appeared in 1946 Astounding. Also among these early authors are Lester del Rey, whose first story, “The Faithful,” appeared in 1938 and T.L. Sherred and A. Bertram Chandler.

However, not every great science fiction writer could write for Campbell. They didn’t have the “Campbell touch.” One such writer is Frederic Brown and another, most famous writer, Ray Bradbury.

Campbell’s influence continued into the 50’s and 60’s, until his death in 1971. Sadly, toward the end of his life, he was involved with several “pseudo science” topics including his promotion of “General Semantics,” a theory of logic that was adopted by Campbell, and some of his writers, including A.E. van Vogt in his novel “The World of Null-A.” The name “Ā” refers to non-Aristotelian logic. This is logic that includes three or more values and rejects the simple true/false of Aristotle’s thinking.

Later Campbell became a big supporter of Hubbard’s Dianetics and his Scientology, although Hubbard’s other fellow writers and friends had a lot of doubts.

SF writer Alfred Bester, an editor of Holiday Magazine and a sophisticated Manhattanite, recounted at some length his "one demented meeting" with Campbell, a man he imagined from afar to be "a combination of Bertrand Russell and Ernest Rutherford.”

Although Bester only wrote a few science fiction stories, his 1956 “The Stars are my Destination” (also known as “Tiger, Tiger” from the William Blake poem) is, in my opinion, one of the greatest science fiction stories of all time.

Bester states that the first thing Campbell said to him was that Freud was dead, destroyed by the new discovery of Dianetics, which, he predicted, would win L. Ron Hubbard the Nobel Peace Prize. Bester commented: "It reinforced my private opinion that a majority of the science-fiction crowd, despite their brilliance, were missing their marbles.”

Hubbard, another of Campbell’s favorite authors is considered one of the most published writer of all time. In 2006, Guinness World Records declared L. Ron Hubbard the world's most published and most translated author, having published 1,084 fiction and non-fiction works that have been translated into 71 languages. Isaac Asimov and his over 500 published works is also often listed as a most popular writer, but others such as , J.K. Rawling, Agatha Christie, and William Shakespeare hold records too.

To me, in addition to Bester, Asimov — “The Good Doctor” and Arthur C. Clark, the man who first thought up geosynchronous satellites, were some of the greatest writers for the Golden Age and beyond. (And, of course, Heinlein.) I was never that big a fan of Bradbury, but his work is definitely first rate.

For the last twenty-nine years, each year, I purchase and read “The Year’s Best Science Fiction” collection edited by Gardner Dozois. This thick collection of the latest writing by the latest writers is very interesting. Science Fiction is now as much about people as about science and the art form has advanced considerably.

However, I must admit that after completing reading one of these up-to-date stories, I often just don’t get it. I just want to go back to the old stories from the Golden Age. I have already read most all of them, but a failing memory in my “Golden Age” allows me to experience them again in their original freshness. Who says old age has problems.

The Golden Age formed the foundation of modern science fiction and its influence can be traced through the science fiction movies of the fifties to “2001” and “Star Wars.” But more significant is the influence this literature and fiction had on my generation of scientists and engineers, including yours truly.

History of Science -- Part Eighteen: Protons

Ernest Rutherford

Around 460 B.C., a Greek philosopher, Democritus, developed the idea of atoms. He asked this question: If you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break it no further? Democritus thought that it ended at some point, a smallest possible bit of matter. He called these basic matter particles, atoms.

For more than 2000 years nobody did anything to continue the explorations that the Greeks had started into the nature of matter. Not until the early 1800's did people begin again to question the structure of matter.

Then an English chemist, John Dalton performed experiments with various chemicals that showed that matter seemed to consist of elementary lumpy particles (atoms). Although he did not know about their structure, he knew that the evidence pointed to something fundamental.

The German physicist Johann Wilhelm Hittorf studied electrical conductivity in rarefied gases. In 1869, he discovered a glow emitted from the cathode, the part connected to the negative terminal of a battery. In 1876, the German physicist Eugen Goldstein showed that the rays from this glow cast a shadow, and he dubbed the rays cathode rays.

During the 1870s, the English chemist and physicist Sir William Crookes developed the first cathode ray tube to have a high vacuum inside thereafter called the “Crookes’ tube.” He then showed that the luminescence rays appearing within the tube carried energy and moved from the cathode to the anode, the part connected to the positive terminal of the battery. Furthermore, by applying a magnetic field, he was able to deflect the rays, thereby demonstrating that the beam behaved as though it were negatively charged.

In 1896, the British physicist J. J. Thomson, with his colleagues, performed experiments indicating that cathode rays really were unique particles, rather than waves, atoms, or molecules as was believed earlier. Thomson made good estimates of both the charge e and the mass m, finding that cathode ray particles, which he called "corpuscles," had perhaps one thousandth of the mass of the least massive ion known: hydrogen. He showed that their charge to mass ratio, e/m, was independent of cathode material. He further showed that the negatively charged particles produced by radioactive materials, by heated materials, and by illuminated materials were universal. The name electron was proposed for these particles by the Irish physicist George F. Fitzgerald.

These cathode rays and tubes with cathodes and anodes enclosed in a high vacuum became the “high tech” of the first half of the twentieth century. The so called “vacuum tubes” had a cathode “emitter” that was heated by a light bulb-like filament to “boil off electrons.” For example, the 6L6 vacuum tube has a six-volt filament and the 12AT7 has a 12-volt filament. Between the cathode and the anode are one or more screens called “grids.” A triode has a single grid in addition to the cathode and anode. The “A” battery in old radios would provide the filament power and the “B” battery would provide a positive voltage to the anode or “plate” called B+. Vacuum tubes required several hundred volts B+ to operate.

There are vacuum tube “diodes” with only a cathode and an anode. They can’t be used to amplify a signal, but they can be used like one way valves ("valve" is also the British term for a vacuum tube) to change AC current into DC current.

Another form of cathode ray tube or CRT applied a very large negative voltage to the cathode, over a thousand volts in some cases, and then surrounded the sides of a funnel shaped tube with a grounded anode. The electron beam would fly down the middle of the tube and hit a fluorescent screen at the end. The beam would be bent by magnetic fields in a TV and the CRT is called a “picture tube.”

Comparing mass and charge to the simplest atom of all, the hydrogen atom (with its one electron and one proton) soon convinced scientists that this cathode ray consisted of a component of an atom, and that these electrons could be detached from the atom by heat (and, as additional studies showed, by large electric fields and also the photoelectric effect explained by Einstein.)

Since atoms are electrically neutral, it was obvious that an atom must have some positive charged material to offset the negative charge of the electron.

I’ve described before the various theories of a “rice pudding” like atom and that Ernest Rutherford arrived at the correct structure of the electrons spinning around the nucleus. So what is the nucleus made of?

Was the nucleus one solid substance? Further, since we know electrons are very light compared to even the hydrogen nucleus, what forms the nucleus of larger atoms such as carbon, oxygen, iron, or gold.

One theory was that the more massive (and “larger”) atoms were made up of a combination of hydrogen atoms. This concept of a hydrogen-like particle as a constituent of other atoms was developed over a long period. As early as 1815, William Prout proposed that all atoms are composed of hydrogen atoms (which he called "protyles"), based on a simplistic interpretation of early values of atomic weights called “Prout's hypothesis,” which was disproved when more accurate values were measured. (Prout had failed to account for neutrons, which we'll hear about in another chapter.)

Ernest Rutherford was the son of James Rutherford, a farmer, and his wife Martha Thompson, originally from England. James had emigrated to New Zealand from Perth, Scotland, "to raise a little flax and a lot of children." Ernest was born at Spring Grove (now Brightwater), near Nelson, New Zealand.

He studied at Havelock School and then Nelson College and won a scholarship to study at Canterbury College, University of New Zealand where he was president of the debating society, among other things. After gaining his BA, MA and BSc, and doing two years of research during which he invented a new form of radio receiver, in 1895 Rutherford was awarded an "1851 Exhibition Scholarship" to travel to England for postgraduate study at the Cavendish Laboratory, University of Cambridge.

Under the inspiring leadership of J. J. Thomson he managed to detect radio waves at half a mile and briefly held the world record for the distance over which electromagnetic waves could be detected, though when he presented his results at a meeting in 1896, he discovered he had been outdone by another lecturer by the name of Marconi.

In 1898 Thomson offered Rutherford the chance of a post at McGill University in Montreal, Canada. Rutherford accepted, which meant that in 1900 he could marry Mary Georgina Newton to whom he had become engaged before leaving New Zealand. In 1907 Rutherford returned to Britain to take the chair of physics at the University of Manchester.

Along with Hans Geiger and Ernest Marsden in 1909, he carried out the Geiger–Marsden experiment, which demonstrated the nuclear nature of atoms. It was Rutherford's interpretation of this data that led him to formulate his model of the atom in 1911 — that a very small charged nucleus, containing much of the atom's mass, was orbited by low-mass electrons.

In 1917, Rutherford proved that the hydrogen nucleus is present in other nuclei, a result usually described as the discovery of the proton. Rutherford had earlier learned to produce hydrogen nuclei as a type of radiation produced as a result of the impact of Alpha particles on hydrogen gas, and recognized them by their unique penetration signature in air and their appearance in scintillation detectors.

(Alpha particles are two protons and two neutrons bound together. It is the nucleus of the helium atom stripped of its two electrons. Alpha particles, were known before anyone understood the structure of the atom and the nucleus. So called Beta particles are actually high speed electrons (or their antimatter twin, positrons). These “rays” were first discovered in the study of radioactivity and X-rays, which was also part of the discovery of the atom and its components.)

Rutherford knew hydrogen to be the simplest and lightest element and was influenced by Prout's hypothesis that hydrogen was the building block of all elements. Discovery that the hydrogen nucleus is present in all other nuclei as an elementary particle, led Rutherford to give the hydrogen nucleus a special name as a particle, since he suspected that hydrogen, the lightest element, contained only one of these particles.

He named this new fundamental building block of the nucleus the proton, after the Greek word for "first", πρῶτον. Plus, Rutherford also had in mind the word protyle as used by Prout.

The single proton in the nucleus of hydrogen was easy to understand. But what about helium and heavier atoms such as carbon or oxygen. You see, the problem is, what would hold the nucleus together. Recall that we know that like charges repel. So what holds the two protons in helium together in the nucleus, not to mention the six protons in carbon or the eight in oxygen, or the 82 in lead.

To overcome the repulsion of the electric force would require a force even stronger than the electric force. And if this force was so strong, why hadn't it been detected before? Was it a force that was only present in the nucleus of an atom?

Some of the answers hinted at another particle in the nucleus as well as a new force. Up until this point, only gravity and electromagnetic force were known. The study of the nucleus led to a discovery of a third force called the “strong nuclear force.” However, that has to wait for the 1930s and the discovery of the neutron to really be understood. And that leads to the discovery of a fourth fundamental force, also present in the nucleus.

So many questions. So many chapters. Another coming your way.

The History of Science -- Part Nineteen

Feeling Rosey

I was at a concert last night and I ran into Brett Michaels back stage. He was about to go on and perform “Every Rose Has Its Thorn.” I asked if they were going to use any keyboards, and Brett said they planned to just do guitar and drums. I saw a big Hammond B-3 and some Leslie’s in the wings and said if they’d roll that onto the stage I’d just provide a mellow “G – C (add a ninth).” Brett said that would be cool, so I went on with them for that one song.

We got a standing ovation. I really couldn’t see too well over the tall Hammond, but I think people were throwing flowers on the stage.

As I walked off, Axl Rose grabbed me by the arm. He insisted that I play drums for “Paradise City” since he'd fired Steven Adler.

I explained I didn’t know how to play drums, but Axl demanded and said it is an easy beat. So I started out with the simple bass – snare with a double bass beat every fourth measure and a sort of triple bass off the beat in the last bar.

Everything was going so well … then the song began to pick up. All the players kept turning to me and motioning for me to pick it up and add some more … I don’t know what … I guess “drums.”

I was clueless. I told Axl I didn’t play drums. Why didn’t he believe me? Then the audience began to throw things at me and they weren't flowers. I ducked a tomato as a whole cabbage sailed past my shoulder. Now I really wished I’d taken those drum lessons my parents insisted I take.

But nooooooooo, I wouldn't listen to my parents. I wanted to be a rebel. I had to take piano lessons. Now what was I gonna do?

Then I woke up!

History of Science -- Part Seventeen: Bell’s Theorem

John Stewart Bell

By 1935, the basic form of quantum mechanics was clear. Schrödinger’s equation was the new universal law of motion. Although it was only required for objects on the atomic scale, quantum theory presumably governed the behavior of everything. The earlier physics, by then called “classical,” sort of like the ancient Greek theories, was the much easier to use approximation for macroscopic behavior. Nonetheless, quantum science has crept into modern technology in day-to-day objects such as transistors and microprocessors or lasers, items we take for granted today.

Although quantum theory works perfectly, it seems to imply something weird, almost absurd. That has been a problem for scientists and philosophers alike.

Yet quantum theory underlies all physics, which underlies all other sciences. So is all this theory built on sand? Copenhagen insists, and most scientists pragmatically accept the formulas for the practical reason that they work, what’s the problem?

(A minor note: mathematics is not based on physical science. Therefore, math does escape the paradox and does not require interpretation. It is still an unfettered and unrestricted tool, although a fellow by the name of Gödel proved his “Incompleteness Theorem” for mathematics in 1931, which is a sort of “Heisenberg Uncertainty” for math. But mathematical processes still are sharp tools for examining what we don’t know and proving what we can know. Not all is lost to crystal balls and stochastic processes.)

Schrödinger, himself, was bothered by the Copenhagen interpretation. He boiled his concerns down into a thought experiment, now quite famous, called “Schrödinger’s Cat.” It attempts to put the microscopic, quantum world into our macro-world and show the craziness and absurdity of what it implies.

I won’t describe the “cat in the box” story, but Google with quickly provide the details. This experiment has echoed down through the history of quantum theory and led to many an explanation, refutation, and even the title for a book. Stephen Hawkings once said, “When I hear about Schrödinger’s Cat, I reach for my gun.”

That quotation is taken out of context and doesn’t get into the subtleties of what Hawkings has said about it, so time for some more Google-ing. You can spend the better part of the day following the cat / rabbit trail.

As for another often-misquoted scientist, Albert Einstein, he said, “I think that a particle must have a separate reality independent of the measurements. That is, an electron has spin, location, and so forth even when it is not being measured. I like to think the moon is there even if I am not looking at it.”

Einstein rejected the Copenhagen interpretation and spent his lifetime in friendly jousting with Niels Bohr in an attempt to disprove Copenhagen.

Quantum theory has an atom being either a spread-out wave or a concentrated particle. If, on the one hand, you detect it in a single box (or through a single slit), you show it to be a compact particle. On the other hand, it can participate in an interference pattern that shows it to be an extended wave — an apparent contradiction. But the theory is protected from refutation by the Heisenberg uncertainty principle, which shows that checking to see through which slit an atom comes kicks it hard enough to blur any interference pattern. So you thus can’t demonstrate a contradiction.

To argue that quantum theory led to an inconsistency and was therefore wrong, Einstein attempted to show that even though an atom participated in an interference patter, it actually came through a single slit. To demonstrate this he had to evade the uncertainty principle. (Ironically, Heisenberg attributed his original idea for the uncertainty principle to a conversation with Einstein.)

Einstein presented his explanation at the 1927 Solvay conference. Niels Bohr then rose to point out a flaw in Einstein’s reasoning. With simple algebra, Bohr was able to show that the uncertainty principle would foil Einstein’s demonstration.

Three years later, at another conference, Einstein proposed an ingenious thought experiment claiming to violate a version of the uncertainty principle. This one stumped Bohr and he had a sleepless night. By morning, however, he was able to embarrass Einstein by showing that Einstein’s experiment actually violated Einstein’s own general theory of relativity. A humbled Einstein went home from the conference to concentrate on general relativity, his theory of gravity, or so Bohr assumed.

Four years later, in 1935, Einstein wrote a paper with two young colleagues, Boris Podolsky and Nathan Rosen. This paper hit Bohr like a “bolt out of the blue.” The paper, now famous as “EPR” for the three authors, did not claim that quantum theory was wrong, just that it was incomplete. They designed a thought experiment intended to reveal what they believed to be inadequacies of quantum mechanics. To that end they pointed to a consequence of quantum mechanics that its supporters had not noticed.

According to quantum mechanics, under some conditions, a pair of quantum systems may be described by a single wave function, which encodes the probabilities of the outcomes of experiments that may be performed on the two systems, whether jointly or individually.

For example, there is something called “twin-state” particles, such as two photons created together and moving in opposite directions. Quantum theory predicted a particular state for each photon depending on the state of the other. Basically, they are described by a single wavefunction, just like the split electron in two boxes I described in a previous chapter.

So what if the two photons traveled some great distance before one is observed. Then, once observed the wavefunction would collapse to a particular state. But that implied the other photon, now some great distance away, would also have to "decohere" to the opposite state. How would the photon so far away, under the limitations of instant communications denied by relativity, obtain the opposite polarization? How would it “know” that its twin had been “observed”?

In modern terminology we say that the two particles are “entangled”; and it is called “quantum entanglement.” Einstein called it “spooky actions at a distance” and proposed a much simpler explanation that defied quantum theory, namely that the states of the two particles were established when they were emitted and didn’t require an observer or any long distance communications. Recall, he didn’t believe “God plays dice.”

These ideas are often explored in a set of experiments with polarized light. The original paper talked of a complex combination of position and momentum of particles instead of photons of light, but the polarization explanation is considered equivalent and much easier to understand, even to a layperson.

Bohr refuted EPR in a paper, but, like the Copenhagen interpretation, it did leave one with a feeling that something was missing; the explanation seemed more philosophical than scientific, and the argument went on.

Einstein seems in later years to have given up a bit on his view. Although he continued to search for the secrets of the universe, he did write to a friend later, “I have second thoughts. Maybe God is malicious.”

I suspect the continual agreement of all experiments with the descriptions and equations of quantum theory eventually wore Einstein down. (Not that some theories proposed in the intervening years didn’t turn out to be incorrect or incomplete, but the core of Schrödinger’s equations never was found in error … ever.)

The argument was laid to rest in 1970 when John Stewart Bell published his theorem. Bell’s theorem has been called “the most profound discovery in science in the last half of the twentieth century.” It rubbed physics’ nose in the weirdness of quantum mechanics. As a result of Bell’s theorem and the experiments it stimulated, a once “philosophical” question has now been answered in the laboratory.

There is universal connectedness. Einstein’s “spooky interactions” in fact do exist. There is some sort of connection between two particles in certain situations that can exist over great distances and seemingly defy relativistic speed constraints.

These “entanglements,” as modern science calls them, are part of the new frontier of physics. Bell’s theorem lays to rest, once and for all, Einstein’s argument about hidden variables. No, matter and behavior at atomic levels actually is probabilistic and cause-effect has a new interpretation.

Both Einstein and Bohr died before Bell’s explanation. We are sure Bohr would have predicted the experimental result confirming quantum theory. It is not clear what Einstein would have predicted had he seen Bell’s proof. He said he believed that quantum theory’s predictions would always be correct. How would he feel if the predicted result was an actual demonstration of what he denied as “spooky actions”?

The universal connectedness predicted by quantum theory (“Thou canst not stir a flower / Without troubling a star”) is now demonstrated routinely in the laboratory. So, is "non-locality" incompatible with fundamental relativity? Or is space-time folded — just one speculated result of Bell's theorem.

It supports wild speculations. It also, like the rest of quantum mechanics, just works. Now let’s use it to dig deeper into the nucleus.

The History of Science -- Part Eighteen

History of Science -- Part Sixteen: Copenhagen Interpretation

Werner Heisenberg

The meaning of Newton’s mechanics is clear. It describes a “clockwork universe.” It needs no “interpretation.” Einstein’s relativity is surely counterintuitive, but no one interprets relativity. We get used to the idea that moving clocks run slow or that space is non-Euclidian. It’s harder to accept the quantum theory premise that observation creates the reality observed. That requires interpretation.

Physics is supposed to be about the physical. Now we find we need to interpret what physics has found (and proved), almost like Daniel interpreting King Nebuchadnezzar’s dream. Physics is supposed to be about material things, not supernatural, mental, or spiritual!

Filling that need for interpretation, within a year after Schrödinger’s equation, the “Copenhagen interpretation” was developed at Bohr’s institute in Copenhagen with Niels Bohr as its principal architect. Werner Heisenberg, his younger colleague, was the other major contributor. Although there is no “official” version, there is a general understanding of three principles that make up the interpretation.

Copenhagen softens the interpretation of “observation,” describing it as taking place whenever a microscopic, atomic-scale, object interacts with the macroscopic. When a piece of photographic film or a sensor “observes” the photon, or when a Geiger counter clicks in response to a particle entering a discharge tube, etc., we say the event has been observed.

The three pillars of Copenhagen consist of:

1) The probability interpretation of the wavefunction.

I’ve explained this previously. I described the waviness in a region (technically the absolute square of the wavefunction) as the probability that the object will be found in that region. This is central to the Copenhagen interpretation.

But, remember, it isn’t like the likelihood of winning (or loosing) the lottery. In the “two boxes” experiment the object actually was in both boxes until the wavefunction is collapsed by an observation. I suppose you could consider you might win or loose the lottery before the winning number is drawn, that isn’t what’s going on here. It is sort of as if you have both won and lost … you’ve gotten the money and you’ve torn up the loosing ticket … until the winning number is drawn.

This is hard to grasp. That’s why I keep repeating it. To quote another physicist, Pascual Jordan, one of the founders of quantum theory, “Observations not only disturb what is being measured, they produce it.” That’s the essence of the “superposition state.”

While classical physics is strictly deterministic, quantum mechanics tells of the ultimate randomness in Nature. At the atomic level, God does play dice.

Cosmologist John Wheeler puts it concisely, “No microscopic property is a property until it is an observed property.” Bohr said, “There is no quantum world. There is only an abstract quantum description. It is wrong to think that the task of physics is to find out the how nature is. Physics concerns what we can say about nature.” Some would be even less tactful and just say, “Shut up and compute.”

Einstein rejected Bohr’s attitude as defeatist, saying he came to physics to discover what is really going on, to learn “God’s thoughts.” Schrödinger also rejected the Copenhagen interpretation.

Would Bohr actually deny that a goal of science is to explain the natural world? Perhaps not; he once said, “The opposite of a correct statement is an incorrect statement, but the opposite of a great truth may be another great truth.”

Is there another “great truth” out there still to be discovered? Is this just an episode of the “X Files”? Yeah, I sometimes think that. So, am I Fox Mulder or Dana Scully? What about you? Are you the believer or the skeptic?

2) The Heisenberg uncertainty principle.

Bohr’s assistant, Heisenberg, showed that any demonstration to refute the Copenhagen interpretation’s claim of observer-created reality would be frustrated.

His principle describes a fundamental limit to measurement. If one choses to measure the position of a particle very accurately, then you can’t measure the velocity accurately. And, vice-versa attempts to measure the velocity accurately, limit the ability to measure the location.

For example, to observe an atom with a microscope, one must bounce a photon off the atom that is then reflected into the microscope. But the photon will change the motion or position of the atom. The measurement has limits … and it is not just that the scientist needs to build a better measurement tool. It is not the tool at fault, it is the principle. Sure, the impact of measuring either position or motion will change the other. But it is really more of a fundamental issue, not just a statement about the experiment apparatus.

Again Planck’s constant appears. That is the true limit. As you design an experiment to measure either property precisely, you disturb the other property and the product of the measurement accuracy is always greater than or equal to Planck’s constant. (That’s a non-precise statement of Heisenberg’s equation. It is the “delta” or variation of the position measurement times the delta of the velocity measurement must be greater than or equal to Planck’s constant.) If you reduce the delta of one of the measurements, that must cause the uncertainty or delta of the other to increase.

Like most of these quantum theories, Heisenberg’s uncertainty principle has also been proven time and time again by all kinds of ingenious experiments.

Heisenberg’s uncertainty applies to other quantum characteristics too, such as energy or spin. The uncertainty principle can also be derived directly from the Schrödinger equation.

The uncertainty principle comes from the wave-like property of quantum mechanics and the uncertainty principle actually states a fundamental property of quantum systems, and is not a statement about the observational success of current technology.

This basic limitation to both experiment and interpretation is now well accepted, regardless of other views and theories. Yet it isn’t quite enough to prevent certain contradictions in accepted quantum theory.

That leads to the third principle:

3) Complementarity

Copenhagen invokes the “complementarity” principle to confront a spooky aspect of observation: the instantaneous collapse of an object’s wavefunction everywhere by an observation anywhere.

Bohr understood that the two possibilities of an object being both a wave, spread-out and probabilistic as well as a real particle when observed is contradictory. So he supposed a concept called “complementary,” which allows the contradiction since we must consider only one aspect at a time. That’s what we mean when we say the wavefunction collapses upon observation. The contradictory view disappears, leaving us with a physical object. This covers both Schrödingers equations and the observed dual nature of both waves like electromagnetic waves and photons as well as matter such as electrons and atoms also having this dual nature and wave-like properties.

Recall that the spread-out wave could cover a lot of space. So the collapse to a physical object would suddenly put all the matter, or all the information, in one specific location. If the wavefunction really were spread-out matter, then that matter (or even energy or information) would have to move faster than the speed of light to collect in one place. As crazy as all we’ve talked about so far, we don’t think that happens. As kooky as the probability wave interpretation seems to be, it would be downright impossible to believe the object is actually smeared out across space. Remember, there is only the wave, not the wave and the particle, it is just the wave … until observation. Then there is just the particle.

What we are left with is the view that all we can understand is the results of our experiments. Stop worrying about what “really” happens. That we can’t know. We just know the click of the Geiger counter, the trail in a cloud chamber, the flick of a meter, the view in the microscope, the computer printout of the sensor data … all macroscopic phenomenon.

This almost appears to eliminate all physical objects at the atomic level. It appears that all we have are the measurements of our instruments and the design of our experiments. We can’t speak of atoms directly because we can’t observe them directly like we can a rock or water.

(This is no longer true. IBM labs produced one of the first photographs of actual atoms — atoms of argon. They even moved them around and spelled out “IBM.” So this “we can’t see or know” explanation is getting a bit thin. Modern, young physicists are continually challenging these explanations, even if they have been accepted as Gospel for almost one hundred years.)

This calls back Newton’s response when asked just what gravity “is.” He answered, hypothesis non fingo which means, “I make no hypothesis.” He didn’t claim to explain gravity. His equations simply predicted how it works. Einstein did extend that, giving great insight into the nature of space and time. Will some new “Einstein” eventually describe what is really going on in quantum physic?

Essential to the Copenhagen interpretation is a clear separation of the quantum microworld from the classical macroworld. May we some day eliminate the need for the Copenhagen interpretation in favor of a true story of Nature?

Only time will tell. So far we haven’t. Copenhagen is the primary explanation used today. Sure there are others like the “Many Worlds” explanation so popular with science fiction writers, and several more, but Copenhagen has stood the test of time and it is what is taught today.

So what about Einstein? Did he try to come up with an interpretation. You bet. That’s next.

The History of Science -- Part Seventeen