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.

7 Top-Rated Portable Air Conditioners You Can Buy Right Now

Black + Decker/Amazon
Black + Decker/Amazon

The warmest months of the year are just around the corner (in the Northern Hemisphere, anyway), and things are about to get hot. To make indoor life feel a little more bearable, we’ve rounded up a list of some of the top-rated portable air conditioners you can buy online right now.

1. SereneLife 3-in-1 Portable Air Conditioner; $290

SereneLife air conditioner on Amazon.

This device—currently the best-selling portable air conditioner on Amazon—is multifunctional, cooling the air while also working as a dehumidifier. Reviewers on Amazon praised this model for how easy it is to set up, but cautioned that it's not meant for large spaces. According to the manufacturer, it's designed to cool down rooms up to 225 square feet, and the most positive reviews came from people using it in their bedroom.

Buy it: Amazon

2. Black + Decker 14,000 BTU Portable Air Conditioner and Heater; $417

Black + Decker portable air conditioner

Black + Decker estimates that this combination portable air conditioner and heater can accommodate rooms up to 350 square feet, and it even comes with a convenient timer so you never have to worry about forgetting to turn it off before you leave the house. The setup is easy—the attached exhaust hose fits into most standard windows, and everything you need for installation is included. This model sits around four stars on Amazon, and it was also picked by Wirecutter as one of the best values on the market.

Buy it: Amazon

3. Mikikin Portable Air Conditioner Fan; $45

Desk air conditioner on Amazon

This miniature portable conditioner, which is Amazon's top-selling new portable air conditioner release, is perfect to put on a desk or end table as you work or watch TV during those sweltering dog days. It's currently at a four-star rating on Amazon, and reviewers recommend filling the water tank with a combination of cool water and ice cubes for the best experience.

Buy it: Amazon

4. Juscool Portable Air Conditioner Fan; $56

Juscool portable air conditioner.

This tiny air conditioner fan, which touts a 4.6-star rating, is unique because it plugs in with a USB cable, so you can hook it up to a laptop or a wall outlet converter to try out any of its three fan speeds. This won't chill a living room, but it does fit on a nightstand or desk to help cool you down in stuffy rooms or makeshift home offices that weren't designed with summer in mind.

Buy it: Amazon

5. SHINCO 8000 BTU Portable Air Conditioner; $320

Shinco portable air conditioner

This four-star-rated portable air conditioner is meant for rooms of up to 200 square feet, so think of it for a home office or bedroom. It has two fan speeds, and the included air filter can be rinsed out quickly underneath a faucet. There's also a remote control that lets you adjust the temperature from across the room. This is another one where you'll need a window nearby, but the installation kit and instructions are all included so you won't have to sweat too much over setting it up.

Buy it: Amazon

6. Honeywell MN Series Portable Air Conditioner and Dehumidifier; $400

Honeywell air conditioner on Walmart.

Like the other units on this list, Honeywell's portable air conditioner also acts as a dehumidifier or a standard fan when you just want some air to circulate. You can cool a 350-square-foot room with this four-star model, and there are four wheels at the bottom that make moving it from place to place even easier. This one is available on Amazon, too, but Walmart has the lowest price right now.

Buy it: Walmart

7. LG 14,000 BTU Portable Air Conditioner; $699

LG Portable Air Conditioner.
LG/Home Depot

This one won't come cheap, but it packs the acclaim to back it up. It topped Wirecutter's list of best portable air conditioners and currently has a 4.5-star rating on Home Depot's website, with many of the reviews praising how quiet it is while it's running. It's one of the only models you'll find compatible with Alexa and Google Assistant, and it can cool rooms up to 500 square feet. There's also the built-in timer, so you can program it to go on and off whenever you want.

Buy it: Home Depot

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Common Misconceptions About Dreams

If your nightmares look like Henry Fuseli's The Nightmare (1781), we're so sorry.
If your nightmares look like Henry Fuseli's The Nightmare (1781), we're so sorry.
Henry Fuseli, Detroit Institute of Arts, Wikimedia Commons // Public Domain

Contrary to what Ebenezer Scrooge initially thought in Charles Dickens's A Christmas Carol, nightmares aren’t merely a side effect of eating cheese before bed. In fact, studies have shown that pre-sleep snacks—dairy or otherwise—probably don’t influence your dreams at all. But even if you can’t blame your latest wacky snooze vision on last night’s midnight helping of chicken nuggets, you can try to trace it back to some stressor from your daily life.

Since dream interpretation isn’t an exact science—and sleep in general is one of science’s murkier territories—quite a few myths have arisen about what, why, and how we dream. In this episode of Misconceptions, Mental Floss's own Justin Dodd walks us through some of the more common fallacies about dreams. (And if you’re convinced you never dream, well, he has some news for you on that front, too.)

For more videos like this one, subscribe to the Mental Floss YouTube channel here.