13 Facts About Physicist Niels Bohr

Baron/Getty Images
Baron/Getty Images

Quantum physics might not be the most approachable topic, but there’s a good chance you’ve heard of some of its elemental parts, like atoms. In the early 20th century, Danish physicist Niels Bohr discovered the basic atomic structure—a positively charged nucleus surrounded by orbiting electrons—which laid the groundwork for how we understand atoms today. Here are 13 things you might not have known about Bohr.


Niels Bohr, born in Copenhagen in 1885, was brought up in a family that valued science. His father Christian was a physiology professor at the University of Copenhagen, and he often hosted fellow scientists at his home for lively discussions. Young Niels and his two siblings often listened in, which likely inspired the young student’s future studies. Though he never won, Christian Bohr was nominated for the Nobel Prize by one colleague in 1907 and by two in 1908, all for his research on the physiology of respiration.


Bohr enrolled at the Gammelholm Latin School at age 7 and did well in all of his classes except for composition. According to the Niels Bohr Institute at the University of Copenhagen, he once turned in an essay that contained just two sentences: "A trip in the harbor: My brother and I went for a walk in the harbor. There we saw ships land and leave."

But by secondary school, he was correcting errors that he discovered in his physics textbooks. He excelled in the majority of his studies, and he graduated first in his class. Later in life, he penned a number of philosophical writings on physics, having overcome his youthful aversion to exposition.


Bohr began his university studies in 1903 at the same institution that employed his father, the University of Copenhagen. While he initially studied mathematics and philosophy, he won a physics competition sponsored by the Royal Danish Academy of Sciences, and he soon changed his major to physics. Bohr studied other fields, including inorganic chemistry, perhaps less successfully: He earned a reputation for causing explosions in the lab, and eventually broke a record amount of glass at the school. He would, however, go on to earn a master’s degree in 1909 and a doctorate in 1911 in physics.


After graduating, Bohr continued his studies at Cambridge University under J.J. Thomson, who had discovered the electron in 1897. Thomson had turned his attention to cathode rays, which were then believed to be part of the ether—a theoretical, weightless substance found everywhere in the universe. But he eventually determined that the rays were actually particles even smaller than the atom by showing that they could be deflected by electricity. This led Thomson to propose the “plum pudding” structure of atoms, in which negatively charged electrons are embedded in a sphere of positively charged matter, like raisins in a English pudding. Bohr would later contradict the “plum pudding” structure with his atomic model.


After finding his work at odds with Thomson’s, Bohr joined the Manchester University lab of Ernest Rutherford, who had also studied under Thomson. Rutherford had discovered the atomic nucleus through an experiment in which he shot alpha particles at a thin sheet of gold foil. Because some of the particles bounced back instead of going through the gold, he determined the majority of the atom’s mass must be within a small, central nucleus, with the electrons orbiting around it.

This became the foundation of his work with Bohr. The pair studied the structure of the atom, and Bohr determined Rutherford’s model must not be entirely correct. By the laws of physics, the orbiting electrons should eventually crash into the nucleus and destabilize the atom. Bohr eventually tweaked Rutherford’s model by explaining that the electrons orbiting a positively charged nucleus can jump between energy levels, which stabilizes the atoms.


Based on his atomic research, the University of Copenhagen hired Bohr as a professor of theoretical physics in 1916 when he was just 31 years old. Soon after, he began pushing for a new institute for his field, which would allow researchers from all over the world to collaborate with Danish scientists at a state-of-the-art facility. He was granted approval, and the institute opened in 1921 with Bohr serving as director. (His mathematician brother Harald, a former Olympic soccer player, would go on to open the university’s mathematical institute next door nine years later.) In 1965 the university renamed the facility the Niels Bohr Institute, and today more than 1000 staff and students work and study there.


Bohr and Einstein were not only contemporaries; they were good friends who partook in a series of conversations on physics over the course of decades, most notably at the 1927 Solvay Conferences now known as the Bohr–Einstein Debates. They argued two very different positions regarding the observations of electrons behaving as a particle in some experiments and a wave in others, even though an electron shouldn’t be able to be both. Bohr theorized the concept of complementarity to explain the phenomenon—that is, something can be two things at once, but we can only observe one of those things at a time. In establishing a fundamental principle of quantum mechanics, Bohr argued that the act of observation of particles brings them into existence, which is known as the Copenhagen Interpretation.

Einstein, on the other hand, argued that particles exist whether or not we actively observe them. (Imagine a very complex version of the “if a tree falls in the forest” question.) Even with their opposing theories, both were awarded the Nobel Prize in Physics in 1922: Bohr for his atomic model, and Einstein for his work on the photoelectric effect (instead of his then-controversial theory of relativity). So how did the two physicists receive prizes for the same thing in the same year? Einstein was actually awarded the 1921 prize a year late, due to a technicality.


Danish beer giant Carlsberg, known for having its own laboratories to promote the study of natural sciences as they related to brewing, invited Bohr to live in its honorary residence, a house near its production facilities given to a deserving artist, scientist, or writer for life. It had a tap connected directly to the brewery for free beer. In 1932, Bohr and his family moved in, and stayed for the next 30 years.

The sweet real estate deal was not Carlsberg’s first interaction with the scientist. The brewery’s foundation helped Bohr pay for his research in England and funded the Institute for Theoretical Physics.


As the Nazis overran Europe at the height of World War II, Bohr helped scientists escaping the regime in Germany by providing them with funding, lab space, and temporary homes in Copenhagen. Bohr himself was forced to flee in 1943 after the Nazis overtook his country—Bohr’s mother was Jewish, and his entire family was persecuted. They fled Denmark on a fishing boat bound for Sweden, then Bohr and his son Aage were smuggled to England in the empty bay of a British Mosquito bomber plane. In London, he consulted with the Canadian and British governments’ ultra-classified program to develop nuclear weapons, code-named Tube Alloys.


In 1939, American officials had learned that Germany was attempting to build an atomic bomb. Five years later, the U.S. government invited Bohr to work on the Manhattan Project, its top-secret program to develop uranium- and plutonium-based nuclear bombs with the purpose of forcing the Axis nations to surrender. For two years, Bohr collaborated with American and British physicists at Los Alamos National Laboratory in New Mexico, using the name Nicholas Baker as a cover. In 1944, he wrote to British Prime Minister Winston Churchill with a progress report:

“What until a few years ago might be considered as a fantastic dream is at present being realized within great laboratories and huge production plants secretly erected in some of the most solitary regions of the United States. There a larger group of physicists than ever before collected for a single purpose, working hand in hand with a whole army of engineers and technicians, are preparing new materials capable of an immense energy release, and are developing ingenious devices for the most effective use of these materials. […]

“One cannot help comparing the situation with that of the alchemists of former days, groping in the dark in their vain efforts to make gold. Today physicists and engineers are, on the basis of firmly established knowledge, controlling and directing violent reactions by which new materials far more precious than gold are built up, atom by atom.”


He was a staunch believer in sharing the science behind nuclear weapons—a view not taken by U.S. and British leaders. Returning to Denmark after the war, Bohr directed his atomic research toward developing sustainable power rather than weapons. He and several colleagues established Risø, a research laboratory with a modern particle accelerator dedicated to developing nuclear energy for peaceful purposes, in the 1950s.

At the same time, Bohr co-founded the European Center for Nuclear Research (CERN), which held conferences and conducted research at Bohr’s Institute for Theoretical Physics for its first five years, prior to moving to Geneva, Switzerland, in 1957. The center now houses the Large Hadron Collider, the world’s largest particle accelerator, which generates electrical fields to speed up the movement of atomic particles and uses magnets to direct their flow. The collisions of the particles reveal information about their properties. Using the Large Hadron Collider, a team of researchers first observed a new type of particle, the Higgs boson, in 2012.


Bohr’s life wasn’t just focused on his work—he was a family man, too. He married Margrethe Nørlund in 1912, and they had six sons, four of whom survived into adulthood. His son Aage would follow closely in his father’s footsteps, becoming not only a physicist, but also the director of the Institute of Theoretical Physics (after his father passed away in 1962) and winner of the 1975 Nobel Prize in Physics for his research into the structure of atomic nuclei. The Bohrs are one of six father-son pairs to have each won a Nobel Prize (Niels Bohr’s professor J.J. Thomson and his son George Paget Thomson are another).


Bohr still contributed to physics after his death—in a way. In 1981, German researchers succeeded in creating a single atom of Element 107, isotope 262, the result of bombarding bismuth atoms with chromium atoms. They named it Bohrium. The highly radioactive element does not occur in nature and, so far, only a few atoms of it have ever been created in a lab.

15 Positively Reinforcing Facts About B.F. Skinner

Silly rabbit via Wikimedia Commons // CC BY 3.0
Silly rabbit via Wikimedia Commons // CC BY 3.0

Burrhus Frederic Skinner was one of the preeminent American psychologists of the 20th century. B.F. Skinner founded “radical behaviorism”—a twist on traditional behaviorism, a field of psychology that focused exclusively on observable human behavior. Thoughts, feelings, and perceptions were cast aside as unobservable.

B.F. Skinner dubbed his own method of observing behavior “operant conditioning,” which posited that behavior is determined solely by its consequences—either reinforcements or punishments. He also coined the term "positive reinforcement." 

To Skinner’s critics, the idea that these “principles of reinforcement,” as he called them, lead to easy “behavior modification” suggested that we do not have free will and are little more than automatons acting in response to stimuli. But his fans considered him visionary. Controversial to the end, B.F. Skinner was well known for his unconventional methods, unusual inventions, and utopian—some say dystopian—ideas about human society.

1. B.F. Skinner invented the "operant conditioning" or "Skinner" box.

Skinner believed that the best way to understand behavior is to look at the causes of an action and its consequences. He called this approach “operant conditioning.” Skinner began by studying rats interacting with an environment inside a box, where they were rewarded with a pellet of food for responding to a stimulus like light or sound with desired behavior. This simple experiment design would over the years take on dark metaphorical meaning: Any environment that had mechanisms in place to manipulate or control behavior could be called a "Skinner box." Recently, some have argued that social media is a sort of digital Skinner box: Likes, clicks, and shares are the pellet-like rewards we get for responding to our environment with certain behavior. Yes, we are the rats.

2. B.F. Skinner believed that all behavior was affected by one of three "operants."

Skinner proposed there were only three “operants” that had affected human behavior. Neutral operants were responses from the environment that had a benign effect on a behavior. Reinforcers were responses that increased the likelihood of a behavior’s repetition. And punishers decreased the likelihood of a behavior’s repetition. While he was correct that behavior can be modified via this system, it’s only one of many methods for doing so, and it failed to take into account how emotions, thoughts, and—as we learned eventually—the brain itself account for changes in behavior.

3. He's responsible for the term "positive reinforcement."

B.F. Skinner eventually moved on to studying pigeons in his Skinner box. The pigeons would peck at a disc to gain access to food at various intervals, and for completing certain tasks. From this Skinner concluded that some form of reinforcement was crucial in learning new behaviors. To his mind, positive reinforcement strengthens a behavior by providing a consequence an individual finds rewarding. He concluded that reinforced behavior tends to be repeated and strengthened.

4. Some critics felt "positive reinforcement" amounted to bribery.

Critics were dubious that Skinner's focus on behavior modification through positive reinforcement of desired behavior could actually change behavior for the long term, and that it was little more than temporary reward, like bribery, for a short-term behavioral change.

5. B.F. Skinner's idea of "negative reinforcement" isn't what you think.

Skinner believed negative reinforcement also helped to strengthen behavior; this doesn't mean exposing an animal or person to a negative stimulus, but rather removing an “unpleasant reinforcer.” The idea was that removing the negative stimulus would feel like a “reward” to the animal or person.

6. B.F. Skinner taught pigeons to play ping-pong.

As part of his research into positive reinforcement, he taught pigeons to play ping-pong as a first step in seeing how trainable they were. He ultimately wanted to teach them to guide bombs and missiles and even convinced the military to fund his research to that effect. He liked working with pigeons because they responded well to reinforcements and punishments, thus validating his theories. We know now that pigeons can be trained in a whole host of tasks, including distinguishing written words from nonsense and spotting cancer.

7. B.F. Skinner's first book, The Behavior of Organisms, broke new ground.

Published in 1938, Skinner’s debut book made the case that simple observation of cause and effect, reward and punishment, were as significant to understanding behavior as other “conceptual or neural processes.”

Skinner believed behavior was everything. Thoughts and feelings were just unreliable byproducts of behaviors, he argued—and therefore dismissed them. Many of his fellow psychologists disagreed. Regardless, Skinner’s theories contributed to a greater understanding of the relationship between stimuli and resulting behavior and may have even laid the groundwork for understanding the brain’s reward circuitry, which centers around the amygdala.

8. B.F. Skinner created the "baby tender."

Skinner was fond of inventions, and having children gave him a new outlet for his tendencies. He designed a special crib for his infant daughter called “the baby tender.” The clear box, with air holes, was heated so that the baby didn't need blankets. Unlike typical cribs, there were no slats in the sides, which he said prevented possible injury. Unsurprisingly, it did not catch on with the public.

9. B.F. Skinner also developed his own "teaching machine."

Silly rabbit via Wikimedia Commons // CC BY 3.0

You may have Skinner to thank for modern school workbooks and test-taking procedures. In 1954 Skinner visited his daughter’s classroom and found himself frustrated with the “inefficiencies” of the teaching procedures. His first "teaching machine"—a very basic program to improve teaching methods for spelling, math, and other school subjects—was little more than a fill-in-the-blank method on workbook or computer. It’s now considered a precursor to computer-assisted learning programs.

10. Skinner imaged an ideal society based on his theories of human behavior.

Skinner admired Henry David Thoreau’s famous book Walden, in which Thoreau writes about his retreat to the woods to get in greater contact with his inner nature. Skinner's "Ten Commandments" for a utopian world include: “(1) No way of life is inevitable. Examine your own closely. (2) If you do not like it, change it. (3) But do not try to change it through political action. Even if you succeed in gaining power, you will not likely be able to use it any more wisely than your predecessors. (4) Ask only to be left alone to solve your problems in your own way. (5) Simplify your needs. Learn how to be happy with fewer possessions.”

11. B.F. Skinner wrote a utopian novel, Walden Two.

Though inspired by Walden, Skinner also felt the book was too self-indulgent, so he wrote his own fictional follow-up with the 1948 novel Walden Two. The book proposed a type of utopian—some say dystopian—society that employed a system of behavior modification based on operant conditioning. This system of rewards and punishments would, Skinner proposed, make people into good citizens:

“We can achieve a sort of control under which the controlled, though they are following a code much more scrupulously than was ever the case under the old system, nevertheless feel free. They are doing what they want to do, not what they are forced to do. That's the source of the tremendous power of positive reinforcement—there's no restraint and no revolt. By careful cultural design, we control not the final behavior, but the inclination to behave—the motives, desires, the wishes.”

12. Some felt Skinner's ideas were reductionist ...

Critics, of which there were many, felt he reduced human behavior to a series of actions and reactions: that an individual human “mind” only existed in a social context, and that humans could be easily manipulated by external cues. He did not put much store in his critics. Even at age 83, just three years before he died, he told Daniel Goleman in a 1987 New York Times article, “I think cognitive psychology is a great hoax and a fraud, and that goes for brain science, too. They are nowhere near answering the important questions about behavior.”

13. ... and others were horrified by Walden Two.

Astronomer and colleague JK Jessup wrote, “Skinner's utopian vision could change the nature of Western civilization more disastrously than the nuclear physicists and biochemists combined.”

14. B.F. Skinner implied that humans had no free will or individual consciousness.

In the late 1960s and early '70s, Skinner wrote several works applying his behavioral theories to society, including Beyond Freedom and Dignity (1971). He drew fire for implying that humans had no free will or individual consciousness but could simply be controlled by reward and punishment. His critics shouldn't have been surprised: this was the very essence of his behaviorism. He, however, was unconcerned with criticism. His daughter Julie S. Vargas has written that “Skinner felt that by answering critics (a) you showed that their criticism affected you; and (b) you gave them attention, thus raising their reputation. So he left replies to others.”

15. He died convinced that the fate of humanity lay in applying his methods of behavioral science to society.

In 1990, he died of leukemia at age 86 after receiving a Lifetime Achievement Award from the American Psychological Association. Proud of his work, he was nonetheless concerned about the fate of humanity and worried “about daily life in Western culture, international conflict and peace, and why people were not acting to save the world.”

A New DNA Test Will Break Down Your Cat's Breed


Modern DNA testing kits can reveal a lot of information about you just by sending your spit off to a lab for analysis. As a result, it's easier than ever to learn about your personal ancestry and health risks. And now, the same goes for your cat, too.

Basepaws is now offering what it calls the "world's first DNA test for cats," which can tell you which breeds your beloved fur baby likely descended from, in addition to other information about their characteristics. The CatKit will reveal whether your little Simba is more similar to an American Shorthair, Abyssinian, or one of the other 30 breeds on record, as well as determining which of the "big cats" (think lions) your kitty has the most in common with.

Here's how it works: After receiving your kit in the mail, you will be asked to collect a DNA sample from your feline friend. The current kit includes adhesives for collecting cat hair, but Basepaws will soon roll out new kits that call for saliva samples instead. (This will provide a more consistent DNA sample, while also allowing staff to process more samples at once, according to a company spokesperson. It also will make it easier to collect samples from hairless cats like Sphinxes.)

A cat DNA test result

Once you collect the sample, just mail it in and wait eight to 12 weeks for your report. Basepaws uses sequencing machines to "read" your kitty's genetic code, comparing it to the sequences of other cats in its network. "More than 99 percent of your cat's genetic sequence will be similar to every other cat; it's the small differences that make your cat unique," Basepaws writes on its website.

In the future, Basepaws will also be able to determine your cat's predisposition for certain diseases, as well as their personality and physical traits. The company holds on to your cat's genetic data, allowing it to provide updates about your cat as the Basepaws database continues to grow.

Order a kit on the Basepaws website for $95. Enter the code "MEOWRCH-I5W3RH" at the checkout for a 10 percent discount.

And don't feel left out if you're a dog lover rather than a cat person—Wisdom Panel offers a similar service for canine companions. Its kit is available for $73 on Amazon.