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An excellent female physicist who missed the Nobel Prize

Lise Meitner (1878 – 1968)
She was born in Vienna, Austria, as the third of eight children of a Jewish family.

It was hard for female to go and study in higher education at that time, so she decided to be a French teacher after high school. However, she could not give up studying at a university.

Fortunately, the social environment encouraged women to go to Universities then. Lise took the exam and entered the University of Vienna in 1901. She was major in physics and studied under Ludwig Boltzmann.

She went to The University of Berlin in 1907 to study under Max Planck. Then, she found a research job with the chemist Otto Hahn. Lise and he started studying radioactivity, with her insight of physics and his ability of chemistry. In 1918, they discovered the element protactinium.

In 1934, Lise was fascinated with the paper proposing nuclear fusion by Enrico Fermi, and she wanted Hahn to work on this experiment together. The project started, but Hahn had to dismiss Lise later due to political pressure from Nazi Party.

After that, Hahn observed an unexpected result from an experiment, but he was not sure to explain this. Then, he consulted Lise about the result. Lise and her nephew (physicist) proved that it was the nuclear fission.

Unfortunately, Lise Meitner did not get awarded Nobel Prize for the series of experiments, but she surely played an important role in finding nuclear fission.

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Discrete dynamics and its applications to our daily lives

Math, physics, engineering, and our lives are closely related. Physics formulates the nature’s motion with mathematics. This provides applications to creating a convenient system for our living.

Let us introduce a two dimensional discrete mapping:
x_(n+1) = 0.6x + y + 5.2/(1.0 + x^2)
y_(n+1) = -0.9999x
The plot is shown as a picture above.

The above equation is a mathematical example, but such model can be used to analyze population growth, radioactive decay, pollution control, medication dosages, robotics, etc.

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Complicated waves made from a simple equation

Speaking of waves, we come up with ocean. Wind creates complicated shapes of waves as you know.

Waves have an interesting property that is called principle of superposition. Each wave oscillates up and down. When an up-wave and a down-wave collide at a point, the both waves appear to be vanished if both waves have an equal amplitude.

Sounds and electromagnetic waves also have the same property.

The picture is expressed by the equation, sin(x^2)-cos(y^2)-sin(x*y).

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Gravity on Saturn: If you go there, how do you feel?

Question:

How strong is the gravity on the surface of Saturn?

a) About 0.5 times as strong as that on Earth
b) About 1 times as strong as that on Earth
c) About 2 times as strong as that on Earth
d) About 6 times as strong as that on Earth
e) About 10 times as strong as that on Earth

 

 

The answer is b). The gravitational acceleration is proportional to its mass, but inversely proportional to the square of the radius. Saturn is less dense than Earth.

Photo via Visual Hunt

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Georg Simon Ohm’s biography: How Ohm’s law was formulated

Georg Simon Ohm (1789 – 1854)

He was born in Bayern State in Germany. His father studied math, physics, and philosophy by himself and taught his children what he learned.

Because he learned enough from his father, Georg thought that he wouldn’t learn anything in school when he was eleven years old. After completing the college, he started working as a math teacher.

Although he was major in mathematics, he got a chance to teach physics in schools. He was gradually fascinated with electric phenomena discovered by Oersted. He got engaged in figuring out the mathematical aspect of electricity. Georg discovered that the magnitude of current in a metal wire is proportional to its cross-sectional area and inversely proportional to its length. In addition, he formulated that the resistance is equal to the voltage divided by the current in a circuit, which is called Ohm’s law nowadays.

His performance is based on the experiments and mathematical logic; however, he was not evaluated by German science society for a long time. Allegedly, the strong influence of idealism of philosophy might have prevented it from accepting Ohm’s way to analyze the whole.

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The gravitational wave, the way to understand it in terms of our daily lives

The gravitational waves were detected in February 2016, which was the very first time. After a few months, the scientists again detected another gravitational waves, and they found more details of how the waves were generated by spinning of black holes.

By the way, it sounds too far from our daily lives, doesn’t it? You may wonder about what those scientists are doing? What is the gravitational wave? Why is the black hole?

You can read the theoretical details in other “enthusiastic” websites or papers, but I would like to explain it in terms of what we have.

You know electromagnetic waves that are used for many of our technologies, such as cell phones, radios, wireless network, etc. In fact, the waves are created with electrically charged particles. More precisely, oscillation of the particles emit electromagnetic waves, which was experimentally proven a long time ago.

Now, we can get back to the gravitational wave. Gravity is induced by its mass. If we analogize this to the electromagnetic wave, oscillation of mass can generate the wave of gravity. That is also derived from what Einstein predicted.

Then, why was it really difficult to detect the gravitational wave? This is because the gravitational force is way too much weaker than the electromagnetic force. It depends on particles, but if the electromagnetic force is 1, the gravitational force is 0.0000000000 0000000000 0000000000 0000000001.

Therefore, in order to detect the gravitational wave, the mass to be oscillated must be very large. Black holes are actually very massive.

Let’s summarize it. The gravitational waves are similar to electromagnetic waves. However, the gravitational waves are very weak, so the massive black holes had to be used for the experiment and the technologies also had to be highly sophisticated.