17 Little-Known Facts About Max Planck

Hulton Archive/Getty Images
Hulton Archive/Getty Images

These days, Max Planck’s name comes up most by way of the prestigious scientific institutes named after him. (The Max Planck Society runs 83 throughout Germany and the world.) But who was the real Max Planck, and why would there be so many research centers in his name? Here are 17 facts about the theoretical physicist.


There are two theories that modern physics uses to explain the universe. There is relativity—Einstein’s work—and there is quantum theory, invented by Planck. In the late 1890s, he began his work studying thermal radiation and found a formula for black-body radiation, one that eventually became Planck’s Law. To explain why his formula worked, he introduced the idea of packets of energy he called “quanta,” giving rise to the branch of quantum physics.

He himself was surprised at the radical nature of his own discoveries, writing, “My futile attempts to put the elementary quantum of action into the classical theory continued for a number of years and they cost me a great deal of effort.”

By the time he died, though, Planck was a legend in the scientific world. “Max Planck was one of the intellectual giants of the 20th century and one of the outstanding intellects of all time,” The New York Times wrote upon his death in October 1947, ranking “with the immortals of science, such as Archimedes, Galileo, Newton, and Einstein.”


Planck helped popularize the term “theory” to describe Einstein’s relativity work. In a 1906 talk, he referred to the model of physics put forth by Einstein as “Relativtheorie,” which became “Relativitätstheorie,” or “relativity theory.” Einstein himself referred to it as the “relativity principle,” but Planck’s terminology caught on.


Planck was a highly respected academic in his lifetime. As science writer Barbara Lovett Cline explains, “In Germany at this time only princes and barons were accorded more respect than professors,” and Planck was no exception. He racked up a multitude of awards in his academic career before finally winning the Nobel Prize in Physics at the age of 60. He received more nominations for the Nobel from a wider range of physicists than any other candidate at the time. He finally received the prize for 1918 “in recognition of [his] epoch-making investigations into the quantum theory,” as the president of the Royal Swedish Academy of Sciences said upon presenting the award.


Planck recognized the importance of Einstein’s work on relativity early, and was one of the first important boosters of his theories. “Einstein may be considered Planck’s second great discovery in physics,” J.L. Heilbron writes in his book The Dilemmas of an Upright Man: Max Planck as a Spokesman for German Science, “and his support, in Einstein’s judgment, was instrumental in securing the swift acceptance of new ideas among physicists.” At the time, Einstein didn’t have a Ph.D. or work at a university, and the support of an established, famous scientist like Planck helped usher him into the mainstream. Though he would remain skeptical of aspects of the younger scientist’s work—like his 1915 research on “light quanta,” or photons—the two remained friends and close colleagues for much of their lives. According to Planck’s obituary in The New York Times, “When the Physical Society of Berlin conferred on him a special medal, he handed a duplicate of it to his friend, Einstein.”


Planck was a gifted pianist and almost dedicated his career to music instead of physics. He hosted musical salons at his home, inviting other physicists and academics as well as professional musicians. Albert Einstein attended [PDF], sometimes picking up the violin to play in quartets or trios with Planck. According to Heilbron, “Planck’s sense of pitch was so perfect that he could scarcely enjoy a concert,” lest it be ruined by an off-key note.


Not long after the 16-year-old Planck got to the University of Munich in 1874, physics professor Philipp von Jolly tried to dissuade the young student from going into theoretical physics. Jolly argued that other scientists had basically figured out all there was to know. “In this field, almost everything is already discovered, and all that remains is to fill a few holes,” he told Planck. Luckily, the budding scientist ignored his advice.


Though he was described as a bit dry in front of a classroom, Planck’s students loved him. English chemist James Partington said he was “the best lecturer [he] ever heard,” describing Planck’s lectures as crowded, popular affairs. “There were always many standing around the room,” according to Partington. “As the lecture-room was well heated and rather close, some of the listeners would from time to time drop to the floor, but this did not disturb the lecture.”


In The Dilemmas of an Upright Man, Heilbron describes Planck as an “exact economist with his time.” He ate breakfast precisely at 8 a.m then worked in a flurry until noon every day. In the evenings and during university breaks, though, he relaxed and entertained friends. His routine involved “a rigid schedule during term—writing and lecturing in the morning, lunch, rest, piano, walk, correspondence—and equally unrelenting recreation—mountain climbing without stopping or talking and Alpine accommodation without comfort or privacy,” according to Heilbron.


Planck stayed active throughout his life, hiking and mountain climbing well into old age. In his 80s, he still regularly climbed Alpine peaks reaching more than 9800 feet in height.


“Planck loved merry, relaxed company and his home was the center of such conviviality,” famed nuclear physicist Lise Meitner described in 1958 (as quoted by the Max Planck Society). “When the invitations happened to be during the summer term, there would be energetic games in the garden afterwards in which Planck participated with downright childish glee and great adeptness. It was almost impossible not to be tagged by him. And how visibly pleased he was when he had caught someone!"


Due to his outspoken support of Jewish physicists like Einstein, Planck was labeled by the nationalist Aryan Physics faction of academics as being part of a grand Jewish conspiracy to keep German scientists from appointments in university physics departments Along with other physicists in Einstein’s circle, he was called a “bacteria carrier” and a “white Jew” in the official SS newspaper, Das Schwarze Korps, and his ancestry was investigated by the Gestapo.


Though Planck didn’t always support his Jewish colleagues against the Nazis—he chastised Einstein for not returning to Germany after Hitler came to power and eventually dismissed Jewish members of the Kaiser Wilhelm Society (later the Max Planck Society) due to pressure from the Third Reich [PDF]—he did make several stands against Nazi policies. He fought against the inclusion of Nazi party members in the Prussian Academy and, as president of the Kaiser Wilhelm Society, met with Hitler and appealed to the Führer to let certain Jewish scientists keep their jobs.

It didn't work. In 1935, one in five German scientists had been dismissed from their posts (as many as one in four in the field of physics) and supporting Jewish scientists became increasingly risky. Still, in 1935, Planck convened a commemorative meeting of the Kaiser Wilhelm Society to honor the late Jewish chemist Fritz Haber despite an explicit government ban on attending the event. His prominent support of Jewish scientists like Haber and Einstein and refusal to join the Nazi Party eventually resulted in the government forcing him out of his position at the Prussian Academy of Sciences and blocking him from receiving certain professional awards.


He was one of many apolitical civil servants in German academia who hoped that the worst effects of anti-Semitic nationalism would eventually pass, and who wanted to maintain Germany’s importance on the world scientific stage as much as possible in the meantime. When Hitler began demanding that speeches open with “Heil Hitler,” Planck begrudgingly complied. As physicist Paul Ewald described of his address at the opening of the Kaiser Wilhelm Institute of Metals in the 1930s, “… we were all staring at Planck, waiting to see what he would do at the opening, because at that time it was prescribed officially that you had to open such addresses with ‘Heil Hitler.’ Well, Planck stood on the rostrum and lifted his hand half high, and let it sink again. He did it a second time. Then finally the hand came up and he said ‘Heil Hitler.’ … Looking back, it was the only thing you could do if you didn’t want to jeopardize the whole [Kaiser Wilhelm Society].” As science writer Philip Ball describes, for Planck, the rise of Hitler and Nazi Germany was a “catastrophe that had engulfed him, and which in the end destroyed him.”


Erwin Planck was a high-ranking government official before the Nazis came to power, and although he resigned from political life in 1933, he secretly helped craft a constitution for a post-Nazi government. In 1944, he was arrested and accused of taking part in Claus Stauffenberg’s assassination attempt on Adolf Hitler, in which the Nazi leader was wounded by an exploding briefcase. While it seems that Erwin didn’t directly take part in the bombing plot, he did recruit supporters for the conspirators, and he was sentenced to death for treason. Trying to save his favorite son’s life, the 87-year-old Max Planck wrote personal letters begging for clemency to both Hitler and the head of the SS, Heinrich Himmler. Erwin was executed in 1945.


After World War I, Planck encouraged his fellow scientists to ignore the turbulence of politics to focus on the greater importance of their scientific achievements. “Persevere and continue working” was his slogan.


In his autobiography, Planck described why he chose to pursue physics. “The outside world is something independent from man, something absolute, and the quest for the laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life,” he wrote.


Several discoveries by Planck were eventually named after him, including Planck’s law, Planck’s constant (h, or 6.62607004 × 10^-34 joule-seconds), and Planck units. There is the Planck era (the first stage of the Big Bang), the Planck particle (a tiny black hole), the lunar crater Planck, and the European Space Agency spacecraft Planck, among others. Not to mention the Max Planck Society and its 83 Max Planck Institutes.

Allergies Are On the Rise, and Scientists Have a Good Idea Why


If it seems like everyone around you is constantly sneezing and sniffling, it might be because allergies are on the rise. As New Scientist reports, several studies seem to indicate this is an ongoing trend. While allergies were rare before the mid-20th century, they’re now a common occurrence in children and adults alike. According to the Food Allergy Research and Education Organization, 15 million people in the U.S. have a food allergy.

To make matters worse, some of the fastest-developing countries are seeing a steady increase in allergies, especially in China. Asthma rates among children in Shanghai rose from 2 percent to 10 percent between 1990 and 2011.

So what exactly is at play here? Scientists think the rise in allergies has much to do with how drastically our lifestyles have changed in the last century. In particular, many modern people spend most of their days—and lives—indoors, which wasn’t always the norm. Spending time outdoors at an early age helps expose you to certain microbes “that have helped hone the human immune system for millennia,” New Scientist notes.

For that reason, children who grow up on farms are less likely to develop allergies. However, scientists still don’t understand exactly how these microbes help prevent our immune system from producing Immunoglobulin E, which is released in response to an allergen coming into contact with the body.

Fortunately, there are ways to keep your allergies under control, even if you can't prevent them entirely. Showering before you sleep, using an air purifier, and keeping pets off your bed are just a few of the quick tips you can try.

[h/t New Scientist]

The Science Behind Why the Earth Isn't Flat

Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.

On March 24, 2018, flat-earther Mike Hughes set out prove that the Earth is shaped like a Frisbee. The plan: Strap himself to a homemade steam-powered rocket and launch 52 miles into sky above California’s Mojave Desert, where he'd see Earth's shape with his own eyes.

It didn't matter that astronauts like John Glenn and Neil Armstrong had been to space and verified that the Earth is round; Hughes didn't believe them. According to The Washington Post, Hughes thought they were "merely paid actors performing in front of a computer-generated image of a round globe."

The attempt, ultimately, was a flop. He fell back to Earth with minor injuries after reaching 1875 feet—not even as high as the tip of One World Trade Center. For the cost of his rocket stunt ($20,000), Hughes could have easily flown around the world on a commercial airliner at 35,000 feet.

Hughes isn't alone in his misguided belief: Remarkably, thousands of years after the ancient Greeks proved our planet is a sphere, the flat-Earth movement seems to be gaining momentum. "Theories" abound on YouTube, and the flat-Earth Facebook page has some 194,000 followers.

Of course, the Earth isn't flat. It's a sphere. There is zero doubt about this fact in the real, round world. To say the evidence is overwhelming is an understatement.


Not every celestial body is a sphere, but round objects are common in the universe: In addition to Earth and all other known large planets, stars and bigger moons are also ball-shaped. These objects, and billions of others, have the same shape because of gravity, which pulls everything toward everything else. All of that pulling makes an object as compact as it can be, and nothing is more compact than a sphere. Say, for example, you have a sphere of modeling clay that is exactly 10 inches in diameter. No part of the mass is more than 5 inches from the center. That's not the case with any other shape—some part of the material will be more than 5 inches from the center of the mass. A sphere is the smallest option.

Today the Earth is mostly solid with a liquid outer core, but when the planet was forming, some 4.5 billion years ago, it was very hot and behaved like more like a fluid—and was subject to the squishing effects of gravity.

And yet, the Earth isn't a perfect sphere; it bulges slightly at the equator. "Over a long time-scale, the Earth acts like a highly viscous fluid," says Surendra Adhikari, a geophysicist at the Jet Propulsion Laboratory in Pasadena, California. The Earth has been spinning since it was formed, and "if you have a spinning fluid, it will bulge out due to centrifugal forces." You can see evidence for this at the equator, where the Earth's diameter is 7926 miles—27 miles larger than at the poles (7899 miles). The difference is tiny—just one-third of 1 percent.


The ancient Greeks figured out that Earth was a sphere 2300 years ago by observing the planet's curved shadow during a lunar eclipse, when the Earth passes between the Sun and the Moon. Some flat-Earth believers claim the world is shaped like a disk, perhaps with a wall of ice along the outer rim. (Why no one has ever seen this supposed wall, let alone crashed into it, remains unexplained.) Wouldn't a disk-shaped Earth also cast a round shadow? Well, it would depend on the orientation of the disk. If sunlight just happened to hit the disk face-on, it would have a round shadow. But if light hit the disk edge-on, the shadow would be a thin, straight line. And if the light fell at an oblique angle, the shadow would be a football–shaped ellipse. We know the Earth is spinning, so it can't present one side toward the Sun time after time. What we observe during lunar eclipses is that the planet's shadow is always round, so its shape has to be spherical.

The ancient Greeks also knew Earth's size, which they determined using the Earth's shape. In the 2nd century BCE, a thinker named Eratosthenes read that on a certain day, the people of Syene, in southern Egypt, reported seeing the Sun directly overhead at noon. But in Alexandria, in northern Egypt, on that same day at the same time, Eratosthenes had observed the Sun being several degrees away from overhead. If the Earth were flat, that would be impossible: The Sun would have to be the same height in the sky for observers everywhere, at each moment in time. By measuring the size of this angle, and knowing the distance between the two cities, Eratosthenes was able to calculate the Earth's diameter, coming up with a value within about 15 percent of the modern figure.

And when Columbus set sail from Spain in 1492, the question wasn't "Would he fall off the edge of the world?"—educated people knew the Earth was round—but rather, how long a westward voyage from Europe to Asia would take, and whether any new continents might be found along the way. During the Age of Exploration, European sailors noticed that, as they sailed south, "new" constellations came into view—stars that could never be seen from their home latitudes. If the world were flat, the same constellations would be visible from everywhere on the Earth's surface.

Finally, in 1522, Ferdinand Magellan's crew became the first people to circle the globe. Like Columbus, Magellan also set off from Spain, in 1519, heading west—and kept generally going west for the next three years. The expedition wound up back at the starting point (though without Magellan, who was killed during a battle in the Philippines). And speaking of ships and seafaring: One only needs to watch a tall ship sailing away from port to see that its hull disappears before the top of its mast. That happens because the ship is traveling along a curved surface; if the Earth were flat, the ship would just appear smaller and smaller, without any part of it slipping below the horizon.


But you don't need a ship to verify the Earth's shape. When the Sun is rising in, say, Moscow, it's setting in Los Angeles; when it's the middle of the night in New Delhi, the Sun is shining high in the sky in Chicago. These differences occur because the globe is constantly spinning, completing one revolution per day. If the Earth were flat, it would be daytime everywhere at once, followed by nighttime everywhere at once.

You also experience the Earth's roundness every time you take a long-distance flight. Jetliners fly along the shortest path between any two cities. "We use flight paths that are calculated on the basis of the Earth being round," Adhikari says. Imagine a flight from New York to Sydney: It would typically head northwest, toward Alaska, then southwest toward Australia. On the map provided in your airline's in-flight magazine, that might look like a peculiar path. But wrap a piece of string around a globe, and you'll see that it’s the shortest possible route.

"If the Earth were flat," Adhikari says, "the trajectory would be completely different." How different depends on which way the globe is sliced into a flattened map, but if it looked like it does on a Mercator-projection map, it might head east and pass over Africa.

Engineers and architects also take the Earth's curvature into account when building large structures. A good example is the towers that support long suspension bridges such as the Verrazano Narrows bridge in New York City. Its towers are slightly out of parallel with each other, the tops being more than 1.5 inches further apart than their bases. If the Earth were flat, the bottom of the towers would be separated by the exact same distance as the top of the towers; the planet's curvature forces the tops of the towers apart.

And for the last half-century, we've had eyewitness and photographic proof of the Earth's shape. In December 1968, the crew of Apollo 8 left Earth for the Moon. When they looked out of the Command Module windows, they saw a blue-and-white marble suspended against the blackness of space. On Christmas Eve, lunar module pilot William Anders snapped the famous "Earthrise" photograph. It gave us an awe-inspiring perspective of our round planet that was unprecedented in human history—but it wasn't a surprise to anyone.


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