There was physics before Einstein in the same way that there was biology before Darwin. Einstein didn’t just add some new ideas to physics. And he didn’t just add a unifying framework for doing physics, like Newton. Einstein took what people thought was physics, turned it upside down, then turned it inside out.
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There was physics before Einstein… in the
same way that there was biology before Darwin. Einstein didn’t just add some new ideas
to physics. And he didn’t just add a unifying framework for doing physics, like Newton.
Einstein took what people thought was physics, turned it upside down, then turned it inside
out. In the same way Darwin’s work made people
see life itself differently, Einstein’s work made humanity reexamine time and space. [Intro Music Plays] The classical worldview—associated with
names you know, like Euclid, Aristotle, and Newton—held that the rules governing space
and time were absolute. One meter was always one meter long; one hour would always be one
hour long… Matter was made up of immutable and indivisible
atoms. And energy moved through a medium called ether—because
everything had to move through something, right? God wouldn’t just make, I dunno,
a howling void? And with new disciplines like thermodynamics
and fun applications like steam power and light bulbs, hum
an understanding of the fundamental
forces of nature seemed pretty solid. To quote historian of science Milena Wazeck, by 1900, “physics was perceived by many to be an almost completed
discipline.” But within this almost-completeness lurked
many unanswered questions. One of the biggest was the failure of the Michelson–Morley
experiment in 1887. They’d attempted to demonstrate that the speed of light changed
just a little when measured from the earth, which is always moving, relative to the ether
,
which never moves. But despite meticulous efforts, they couldn’t
find any slowing-down. Light moved at a constant speed—almost as if there was no ether.
Then there was the electron and radioactivity. In 1897, English physicist J. J. Thomson showed
that cathode rays were made up of discrete particles, way smaller than whole atoms—electrons.
And around the same time, Marie Curie proposed the theory of radioactivity, which classical
physics didn’t predict. Then, in the early 1900s, Ernest Rutherf
ord
experimented on radioactive decay. He named radioactive alpha, beta, and gamma particles,
classifying them by their ability to penetrate different kinds of matter.
And Henri Becquerel measured beta particles and realized they were actually
electrons exiting the nuclei of atoms at high speeds.
So by the early 1900s, radioactive decay was understood, and the crisis of the immutable
atom was as deep as the crisis of the ether. A bunch of folks were investigating Maxwell’s
equations and looking
at black-body radiation, or the heat emitted by dark objects when they
absorb light. Then Heinrich Hertz, the original radio wave
guy, discovered the photoelectric effect, or the paradox that certain metals produce
electrical currents when zapped with wavelengths of light above a certain threshold.
Things started to get messy. Energy was thought to be a continuous wave. But according to
wave-based theory, there might be infinite energy radiated back by black bodies zapped
with certain wavelength
s. This seemingly violated the newly established laws of thermodynamics. Like, infinite energy doesn't seem right.
So, in trying to explain the weird results about light and heat, German physicist Max
Planck theorized that light may not be a wave after all, but a series
of particles or quantum units. All very non-“classical.” Sorry, Aristotle!
Check out Crash Course: Physics for more about quantum weirdness!
Enter Albert. Einstein was born in 1879 and grew up in southern
Germany, Italy, and Swit
zerland. He dropped out of high school, then studied to teach
physics and math and became a Swiss citizen. But he couldn’t get a teaching job—because
he was Jewish. So in 1901 he took a job at the patent office
and started a Ph.D. at the University of Zurich, which he finished in 1905. You’re going
to want to remember that year…. 1905. Now, Al wasn’t an academic hotshot or self-funded
amateur. He was a working-class nobody who did physics on the side. But he was also a
patent officer who spent h
is days pouring over technical documents.
He was an outsider obsessed with math because math is beautiful, and yet he was a deeply
practical person who believed that good math and science could be communicated plainly.
Plus, he was young and bold. And he had a super smart and supportive first wife, Serbian
mathematician Mileva Marić. So, the year he finished his Ph.D., 1905, Al published his dissertation and four papers
that changed physics overnight. This was his annus mirabilis or miracle year
, like 1666 had been for Newton. Help us out, ThoughtBubble.
At age twenty six, Einstein published revolutionary work on: 1. Brownian motion, or the random motion of particles
in fluids; 2. the photoelectric effect, supporting the idea
of energy as a series of particles, not a wave; 3. the equivalence of mass and energy; and 4.special relativity. Special relativity, especially made Einstein
a scientific rock star. He proved that nothing can move faster than light. This explained
why Michelson an
d Morley hadn’t observed light slowing in ether. And a lot of other things.
Einstein got rid of all reference frames for space and time. There was no longer some universal
space in which physics happened. All measurements became relative to the position and speed
of the observer. Space and time became one mathematically continuous
spacetime. So an event at one time for observer A could take place at a completely different
time for observer B. And the only constant in the entire system
became the
speed of light—which classical physics predicted could change!
From special relativity followed the equivalence of mass and energy proof. Which was also mind-blowing.
It’s probably the most memorable physics formula ever, since it’s printed on mugs
and T-shirts the world over: E = mc2. Or, energy equals mass times the speed of light,
squared. Or, mass and energy can be converted into each other!
Or, as Einstein said: “…mass and energy are both but different manifestations of the
same thing—a so
mewhat unfamiliar conception for the average mind.”
Now, it’s important to note that Einstein’s new system of physics is simply a different
system than Netwon’s. “Mass” and “energy” mean something different in the two systems—because,
to put it bluntly, Newton’s system turns out to be not so universal. It only seems
to work on earth, because we aren’t particularly massive or fast-moving, compared to stars. Thanks Thought Bubble. We don’t have time
to explain all of the cool science that Einstein
and his generation of physicists did around
World War One, but two things stand out: In 1915, Einstein published the theory of
general relativity. Special relativity was all about comparing physical effects from
different observer positions in terms of velocity, or speed in a particular direction.
General relativity provided all of the complicated math regarding relativity and acceleration,
or speeding up or down. General relativity explains the physics of
all situations. Special relativity is
one specific case of general relativity.
General relativity nailed the coffin shut on the classical, Euclidean worldview: now gravity
itself was shown not to be a force like light, but an effect, a distortion in the shape of
space due to mass… So the planets didn’t follow certain paths
because of the attraction of the sun’s gravity, but because the space before them was curved
by the sun’s mass. Einstein’s universe wasn’t a series of
perfect spheres in an ether, but a void whose very dimensions—
whose rules, basically,
other than the speed of light—could change. Many of his colleagues initially objected
to this, but Einstein was confident—and patient. Astronomers awaited a solar eclipse
in 1919, that allowed them to experimentally confirm Einstein’s theory. The confirmation of gravitational lensing made
Einstein a scientific hero and an icon of pop culture. As The Times of London reported,
“Newtonian Ideas Overthrown.” The second major act of science Einstein did
around World War One wa
s contribute to the birth of modern particle physics. This story
is about, in part, Einstein getting it wrong. In 1911, Ernest Rutherford and Danish physicist
Niels Bohr [“NEELS BOAR”] theorized a model of the atom with electrons zipping around
a heavy nucleus. Scientists began to study the physics of the very small, just as Einstein
was working out the physics of the very large. But over the 1920s, these particle physicists
saw a lot of weird quantum or particle-like effects.
Basically, Bohr’s
Copenhagen group showed that very small particles tend to act like
particles sometimes but like waves at other times. Like waves, their behaviors have probabilities.
But when measured, individual particles are, well particles. They are or aren’t there.
In 1926, two German physicists worked out the math behind these quantum mechanics: Werner
Heisenberg invented matrix mechanics, which [large exhale] are complex and Erwin Schrödinger,
wave mechanics. And lots of dead/not-dead cat jokes.
Because, i
n 1927, Heisenberg proposed his uncertainty principle: any observer can detect
the position or velocity of any quantum particle, at any given time interval, but not both at
the same time. Einstein haaated this. He believed in a universe
ordered by an ultimate rationality, and he famously quipped, “God doesn’t play dice
with the world.” But Al, who had contributed in lots of ways to the emerging model of atoms
and particles of energy, was wrong about uncertainty. By the 1930s, Einstein was easily
the most
famous scientist since Darwin. There was just one problem. He was still Jewish. And living
in Germany. So in 1933, Einstein renounced his German
citizenship and took a professorship at Princeton. As a celebrity genius with intimate knowledge
of the cutting-edge of German science—and perfect hair—Einstein had the ears of politicians
anxiously planning for another great war in Europe.
And, after one of his physicist buddies demonstrated that an atom could be straight-up, stone-cold
split
open, Einstein felt that he had a moral obligation to explain to the American establishment
just how powerful atomic energy could be… We’ll pick up this thread next time.
Suffice to say, World War Two eventually ended, and a new Cold War started—with scientific
discovery, especially in the physics that Einstein had created, as the new measuring
stick of imperial might. Israel offered Einstein the presidency, which
he turned down. He lived the rest of his life in the home of technological innova
tion and
“fat sandwiches”—New Jersey. Einstein always regretted that his work was
used for violent ends. In fact, he was generally skeptical of modernity. Way back during World
War One, he wrote: “Our entire much-praised technological progress, and civilization generally,
could be compared to an axe in the hand of a pathological criminal.”
And yet, in the end, even the horrors of two world wars never shook his faith that there
was great meaning in the universe—a code to be deciphered by science.
He died never quite accepting quantum randomness, and believing that, one day, humans would
crack the code. Next time—the Americans use Einstein’s
world-threatening Bomb, and warfare changes forever. It’s the birth of nuclear physics,
the end of World War Two, and the beginning of the Cold War. Crash Course History of Science is filmed in the Dr. Cheryl C. Kinney studio in Missoula, MT and it's made possible with the help of all these nice people. And our animation team is Thought Cafe. Crash
Course is a Complexly production. If you wanna keep imagining the world complexly with us, you can check out some of our other channels like Scishow, Eons, and Sexplanations. And, if you'd like to keep Crash Course free for everyone forever, you can support the series at Patreon, a crowd funding platform that allows you to support the content you love. Thank you to all of our Patrons for making Crash Course possible with your continued support.
Comments
Sorry to be nitpicky, but Einstein didn't study at the university of Zurich. He studied at the federal polytechnic school of Zurich, which is today known as ETH Zurich. The university of Zurich is a separate university. But they are next to each other... So close but not quite
"There where physics before Einstein, in the same way that there was biology before Darwin." Pure poetry.
Einstein wasn't against quantum mechanics. His paper on the photoelectric effect is often called the first paper written on quantum mechanics. He just thought people were looking at it the wrong way. Unfortunately, he never figured out the "right" way, but his work on that came up with quantum tunneling.
Wait, you're not going to cover the gold foil experiment? That's even more fun than the double-slit experiment.
What a great way to start off the year. Thanks Hank, complexly, and everyone.
Newton was the Man who explained how Gravity makes things fall And Einstein the Man who explained how it didn't! Absolute Genius.
6:30 So that means you're doing a History of Science, Season 2 eventually, right?
5:27 Nice Interstellar reference. 👍
I watched all of this course in like two days, its so interesting! Thank u and i can’t wait to see more xoxo
IIRC Max Planck actually didn't predict quantum particles. Quantization was just a mathematical "trick" he used to derive the correct equations, but he didn't think it had any physical meaning.
2:50 I think it's wavelenghts BELOW a certain threshold. uv light produces electrons while infrared doesnt.
I love you videos so much! I’ve been watching them for a very long time. You inspired me to create a science channel actually. 😊 but i am just starting, creating some compilations, its poor sofar. Hopefully one day i will have at least a fraction of an impact on effort to get educated as you do. Please, keep it up!
Wonderful! You inspire me to learn more.
Hank: god didn't just make, I don't know, a howling void. Me: Yes he did. it's called the internet
I'm a simple man. I see Einstein, I press like 😂
"Newtonian Ideas Overthrown" -- throwback to when alarmist headlines about scientific discoveries were actually true.
Your pronounciation of "Schrödinger" cracked me up :'D Anglophones are notorious for not even trying but we do kind of love you for it too :)
been binge watching the videos They finished :'( . I was like WTF! Then saw the time stamp. Oh last video just 2 weeks ago. Now waiting for the new videos. Great work keep it up!
I love your videos, keep up the good work!
Hello there