The History of Quantum Physics
It was a sunny afternoon next to an apple tree.
Einstein: (throwing apple in air to himself) I wonder if the energy from this apple increases
gradually or in series of jumps.
Enter Max Planck
Planck: I have been testing this exact phenomenon and concluded that energy equals a fixed
quantity h, later named after me, times frequency of each quantum or particle and in this
situation, an apple.
Einstein: Who are you exactly? You don’t happen to go by Max Planck do you?
Planck: Yes that is me. And you are Albert Einstein.
Einstein: Yes of course, I didn’t think you would be so tall and bald.
Planck: I didn’t think you were so short and have hair everywhere.
Einstein: I would rather have a full head of hair than be tall but anyway, it was your work that I
found astounding and very helpful.
Planck: If you’re talking about my quantum equation on energy well it was something I never
quite believed in but if it is something that has brought you success than I am glad for it.
Einstein: I understand your frustration on the subject as experimentation is the only proof for a
theory.
Enter James Clerk Maxwell
Maxwell: If it wasn’t for my theory based on electromagnetic radiation, we wouldn’t be where
we are today. I introduced that optics, electricity, and magnetism all have a specific wavelength
and frequency.
Einstein: Sir Maxwell, if I may call you that, you did do something great but you had no idea
what this discovery would do. It was thanks to me and Planck and other hard workers that gave
reason for this discovery and that is quantum theory.
Maxwell: BAH! Everybody expands on ideas that are not yet truly determined. I Expanded on
Rudolf Clausius’s mathematical approach on thermodynamics. If not for him I wouldn’t have my
discovery and it not for me there would be no foundation for you and Planck to build upon.
Planck: Ahhh! James Clerk Maxwell. If not for your inspiring work in thermodynamics, who
knows if I would have pursued music or the mysteries of quantum physics. I have nothing but
thanks and respect for what my predecessors have done for quantum physics.
Einstein: For example, it was the theories and discoveries of Ludwig that were later proven
incorrect by you, Planck. You see, our predecessors are important and vital but we are, if not
just as important, more important because we smooth out and polish those rough edges on
earlier theories. You did just that and discovered the polished formula of a blackbody.
Maxwell Exists
Planck: Even those ideas that are polished can be disagreed upon. You described energy as it
relates to light quantum; I described it as, energy of the atoms in a cavity as they interact with
light.
Einstein: I also stated that radiation consists of quanta, or in other words in whole numbers.
That your equation not only explains electromagnetic radiation but its effect on particles’
energy.
Both exit to an oven
Einstein: I concluded in a paper of mine that when a light shines on a metal, individual particles
retain that energy. When the energy is enough, electrons are ejected. The electrons that are
ejected withhold the exact amount of energy it took for the light wave to eject that electron.
Planck: I do remember publishing that paper and I want to tell you I didn’t agree with it.
Einstein: Also, you may have not agreed on me saying that each atom in the cavity had a
quantized energy. Also if each atom has a fixed frequency than the energy of the vibrating atom
can only come in whole number multiples of Planck’s constant. This became known as the
photoelectric law.
Planck: On the contrary, I believed that the energy was equal to all of the atoms’ divided by
Maxwell’s energy equation. At first, I did not want to believe that energy is transferred to the
atoms in quanta and that the radiation itself comes in quanta.
Einstein: Even after all my experiments though I did not want to fully admit that the quanta
exists but rather say the radiation acts as if it does have a quanta.
Enter Neils Bohr
Bohr: According to the type of atom, different wavelengths and frequencies affect different
atoms. For example light affected the hydrogen atom and its energy was absorbed and
reflected.
Einstein: Yes! Your theory of the atom correctly explains Planck’s cavity radiation law.
Bohr: Not only did my theory help you to explain Planck’s cavity law, but I was also able to
support the atomic structure my friend, Ernest Rutherford, proposed through his gold foil
experiment.
Enter Werner Heisenberg and Erwin Schrodinger
Heisenberg: I understand lately that you’re experiment has only worked with hydrogen atoms. I
have introduced the matrix theory which replaces classical commuting variables with noncommuting variables.
Schrodinger: Yes, it was a rather long formula. I simplified it soon enough and also introduced a
second-order differential equation for a wave function. Although I could not explain the
meaning of this function.
Enter Louis De Broglie and Max Born
Born: The wave function is quite peculiar but I managed to determine its true nature . The
absolute value of this wave function expresses a probability amplitude for the outcome of a
measurement.
Bohr: I believe that maybe the quantum jumps and its relation with energy states that would
cause the wave like behavior.
De Broglie: It was intriguing for me to search what waves were associated with on Earth. But I
do not believe the energy states explains its wavelike behavior.
Einstein: Interesting you ask that because I had the exact opposite problem in which I was
trying to describe how the characteristics of waves vary with energy. Something measurable
with waves.
De Broglie: I am familiar with that discovery and I also used the help of Maxwell’s equation to
conclude whether every particle had wave characteristics or not.
Einstein: It was a revolutionary theory and I enjoyed reading about your discovery.
De Broglie: Thank you, what I did to discover the answer to this question was, at first, a particle
with no net force. Once the particle starts to gain momentum the wavelength shortens and also
the wavelength depended on Planck’s constant.
Planck: In short, electrons should act just like light and water waves?
De Broglie: Correct. Experimenters should be able to detect peaks and troughs when shooting
electrons out of a light.
Enter Feynman
Feynman: And so wraps up the basics of quantum mechanics. Each of the theories and
experiments done all connect to one formula E=hf. You should all join my lecture on the nature
of Particles and waves.
All exit to Feynman presentation on double slit experiment
Feynman: We all agree that particles come in lumps, correct? What should we use to represent
particles in our experiment? Lumps basically represent something with definite size and shape.
De Broglie: Bullets shot from a gun should be a fine representation.
Feynman: Very well. Bullets it is. Now picture a board with only two slits in between the gun
and the board catching all the bullets that make it through. Who can predict where the board is
going to catch the bullets?
Einstein: I would assume that, for bullets, that exactly behind each of the slits is where the most
bullets would be caught. The farther away from those 2 points, bullets decrease because the
probability of the bullet going through at smaller angles decreases.
Feynman: Correct! Also just keep in mind that even if we were to close the first slit, collect
bullets, and do the same with the second slit closed and first slit open, we see that the
combined results equal the results as if both of the slits are open at once.
Bohr: If I know particles like I think I know particles they wouldn’t particularly act so uniformly.
Feynman: Lets be patient now Bohr. Now If I replaced the machine gun with an object that is
jiggling up and down at a constant rate and assume it is a tank filled with water. Once the
jiggling begins the water waves are produced. Once the waves go through the slits and hit the
last board, the waves show results of troughs and peaks.
De Broglie: Ahh! Just like the light waves I had tested!
Feynman: You scientists need to let me finish. The last test was to shoot electrons just as the
bullets. I detected that they acted just as waves and showed interference. Now we tried to
detect the electrons flying through each slit to determine how and why they act as waves. To
do this we added a light behind the board with two slits. The electrons suddenly acted as the
bullets did and no longer interfered with one another.
All Scientists: Unbelievable!