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.

1. HE CREATED ONE OF THE PILLARS OF MODERN PHYSICS.

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.”

2. AND HE HELPED NAME THE OTHER ONE.

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.

3. HE WON A NOBEL.

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.

4. HE WAS ONE OF EINSTEIN’S EARLIEST SUPPORTERS.

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.”

5. HE WAS A GREAT MUSICIAN.

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.

6. A PROFESSOR WARNED HIM NOT TO GO INTO PHYSICS.

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.

7. HIS LECTURES WERE STANDING-ROOM-ONLY.

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.”

8. HE KEPT A STRICT SCHEDULE.

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.

9. HE WAS A LIFELONG MOUNTAIN CLIMBER.

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.

10. HE WAS PRETTY GOOD AT TAG.

“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!"

11. THE GESTAPO INVESTIGATED HIM DURING WORLD WAR II.

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.

12. HE PERSONALLY ASKED HITLER TO LET JEWISH SCIENTISTS KEEP THEIR JOBS.

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.

13. BUT HE HAD A COMPLICATED RELATIONSHIP WITH THE NAZIS.

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.”

14. HIS SON WAS LINKED TO A PLOT TO ASSASSINATE HITLER.

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.

15. HIS MOTTO WAS “PERSEVERE AND CONTINUE WORKING.”

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.

16. HE CALLED PHYSICS “THE MOST SUBLIME SCIENTIFIC PURSUIT IN LIFE.”

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.

17. THERE ARE MANY THINGS NAMED AFTER HIM.

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.

Arrokoth, the Farthest, Oldest Solar System Object Ever Studied, Could Reveal the Origins of Planets

NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko
NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko

A trip to the most remote part of our solar system has revealed some surprising insights into the formation of our own planet. Three new studies based on data gathered on NASA's flyby of Arrokoth—the farthest object in the solar system from Earth and the oldest body ever studied—is giving researchers a better idea of how the building blocks of planets were formed, what Arrokoth's surface is made of, and why it looks like a giant circus peanut.

Arrokoth is a 21-mile-wide space object that formed roughly 4 billion years ago. Located past Pluto in the Kuiper Belt, it's received much less abuse than other primordial bodies that sit in asteroid belts or closer to the sun. "[The objects] that form there have basically been unperturbed since the beginning of the solar system," William McKinnon, lead author of one of the studies, said at a news briefing.

That means, despite its age, Arrokoth doesn't look much different today than when it first came into being billions of years ago, making it the perfect tool for studying the origins of planets.

In 2019, the NASA spacecraft New Horizons performed a flyby of Arrokoth on the edge of the solar system 4 billion miles away from Earth. The probe captured a binary object consisting of two connected lobes that were once separate fragments. In their paper, McKinnon and colleagues explain that Arrokoth "is the product of a gentle, low-speed merger in the early solar system."

Prior to these new findings, there were two competing theories into how the solid building blocks of planets, or planetesimals, form. The first theory is called hierarchical accretion, and it states that planetesimals are created when two separate parts of a nebula—the cloud of gas and space dust born from a dying star—crash into one another.

The latest observations of Arrokoth support the second theory: Instead of a sudden, violent collision, planetesimals form when gases and particles in a nebula gradually amass to the point where they become too dense to withstand their own gravity. Nearby components meld together gradually, and a planetesimal is born. "All these particles are falling toward the center, then whoosh, they make a big planetesimal. Maybe 10, 20, 30, 100 kilometers across," said McKinnon, a professor of Earth and planetary sciences at Washington University. This type of cloud collapse typically results in binary shapes rather than smooth spheroids, hence Arrokoth's peanut-like silhouette.

If this is the origin of Arrokoth, it was likely the origin of other planetesimals, including those that assembled Earth. "This is how planetesimal formation took place across the Kuiper Belt, and quite possibly across the solar system," New Horizons principal investigator Alan Stern said at the briefing.

The package of studies, published in the journal Science, also includes findings on the look and substance of Arrokoth. In their paper, Northern Arizona University planetary scientist Will Grundy and colleagues reveal that the surface of the body is covered in "ultrared" matter so thermodynamically unstable that it can't exist at higher temperatures closer to the sun.

The ultrared color is a sign of the presence of organic substances, namely methanol ice. Grundy and colleagues speculate that the frozen alcohol may be the product of water and methane ice reacting with cosmic rays. New Horizons didn't detect any water on the body, but the researchers say its possible that H2O was present but hidden from view. Other unidentified organic compounds were also found on Arrokoth.

New Horizon's flyby of Pluto and Arrokoth took place over the course of a few days. To gain a further understanding of how the object formed and what it's made of, researchers need to find a way to send a probe to the Kuiper Belt for a longer length of time, perhaps by locking it into the orbit of a larger body. Such a mission could tell us even more about the infancy of the solar system and the composition of our planetary neighborhood's outer limits.

The Moon Will Make Mars Disappear Next Week

Take a break from stargazing to watch the moon swallow Mars on February 18.
Take a break from stargazing to watch the moon swallow Mars on February 18.
Pitris/iStock via Getty Images

On Tuesday, February 18, the moon will float right in front of Mars, completely obscuring it from view.

The moon covers Mars relatively often—according to Sky & Telescope, it will happen five times this year alone—but we don’t always get to see it from Earth. Next week, however, residents of North America can look up to see what’s called a lunar occultation in action. The moon's orbit will bring it between Earth and Mars, allowing the moon to "swallow" the Red Planet over the course of 14 seconds. Mars will stay hidden for just under 90 minutes, and then reemerge from behind the moon.

Depending on where you live, you might have to set your alarm quite a bit earlier than you usually do in order to catch the show. In general, people in eastern parts of the country will see Mars disappear a little later; in Phoenix, for example, it’ll happen at 4:37:27 a.m., Chicagoans can watch it at 6:07:10 a.m., and New Yorkers might even already be awake when the moon swallows Mars at 7:36:37 a.m.

If you can’t help but hit the snooze button, you can skip the disappearing act (also called immersion) and wait for Mars to reappear on the other side of the moon (called emersion). Emersion times vary based on location, too, but they’re around an hour and a half later than immersion times on average. You can check the specific times for hundreds of cities across the country here [PDF].

Since it takes only 14 seconds for Mars to fully vanish (or reemerge), punctuality is a necessity—and so is optical aid. Mars won’t be bright enough for you to see it with your naked eye, so Sky & Telescope recommends looking skyward through binoculars or a telescope.

Thinking of holding an early-morning viewing party on Tuesday? Here are 10 riveting facts about Mars that you can use to impress your guests.

[h/t Sky & Telescope]

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