Education changes the world
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
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.
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.
Michael Faraday was a British physicist who contributed to many of important findings for electromagnetic phenomena.
His family was challenged economically, but his siblings and religious belief supported him. In his childhood, he was interested in doing experiments by reading science books.
The turning point of his life came when he audited Humphry Davy’s science lecture. Then, Michael Faraday became his assistant. After a while, Davy found that Faraday had a talent in performing experiments. Faraday was genuinely devoted to finding out electricity in his life.
Now, we are using electricity everyday in our lives, and it becomes indispensable. Without knowing the fundamental theory, we don’t even manufacture cars, airplanes, and a lot of other products.
On the other hand, if we apply such knowledge to what we make, we may be able to create innovative products.
History suggests that the combination between engineering and science changes our life styles and concepts.
I encountered the error when I installed WooCommerce in my WordPress. The general solution is given on this webpage. But it was a little broad to figure out what the problem is in my case.
First, I installed WordPress; install a theme called AZERA Shop; and then I installed a plugin that is WooCommerce. I found the Internal Server Error when I click “Shop” in the menu bar. I tried several suggestions from other webpages, but none of them was able to solve it.
As the above page and others suggested, I decided to edit .htaccess file in the folder.
Here is what I did. After I logged in, I went to “Settings.” There is “Permalinks” in the menu. At the bottom of the page, the proper content of .htaccess is shown. I compared it with what I already had in the server. They were different! I immediately copied the new one and paste it on the old file. After uploading it, the Internal Server Error was gone.
In fact, I remember that I changed the “Site Address (URL)” after installing WooCommerce. (Please go to “General” in “Settings” to find Site Address URL.) Therefore, the .htaccess was modified!
The other point is that my server didn’t let the software change the content of .htaccess file. Then, I kept on getting the error only with shop-related pages.
Hope this will help someone figure out this type of problem.
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