Gravity is one of the most popular concepts in this world. You don’t need to study Physics to experience it. Just grab a weight scale and step on it, we already can see how gravity impacts us so badly. I’m not gonna address what is gravity in details, however, I will write all the funny tales surrounding this bad guy, from the past to the future.
Archimedes
Archimedes was a Greek mathematician, physicist, engineer, inventor, and astronomer, who lived in the ancient world. One of his greatest explorations is the physical law of buoyancy. The principle states that any body completely or partially submerged in a fluid is acted upon by an upward force, whose magnitude is equal to the weight of the displaced fluid by the body. The principle till now has many applications in submarine, ship, and even hot-air balloon function.
Archimedes also found the center of gravity of a system. He postulated that if two equal weights did not have the same center of gravity, the center of gravity of the two weights together would be in the middle of the line that joins their centers of gravity
Galileo’s Town of Pisa
Galileo, a famous physicist living in the 16th century, “the father of observational astronomy”, made many contributions to the physics word in his lifetime. One of those is his experiment to disprove Aristotle’s belief that heavier objects have a higher gravitational acceleration, the Tower of Pisa experiment.
However, many resources state that this experiment actually never happens in physical action, but more likely was a theoretical argument. Galileo assumes that if Aristotle’s belief is right, then let’s bring the situation when we have 2 object balls with different mass ( one is 1M and one is 2M). We will tie these 2 balls with a very light string and drop them from a certain height, let’s say Tower of Pisa. According to our assumption, 1M ball with fall with an acceleration a, and 2M ball will fall faster with an acceleration b (where b is greater than a). Since these 2 balls are tied together with a string, the 1M ball, which is falling slower, will retard the fall of the heavier object via the string. As a result, the whole system (which weighs 3M) will fall slower than the only 2M falling, which, of course, contradicts our assumption.
We can also use Archimedes’s hypothesis above about the center of system to disprove this. We all agree that the center of gravity of this system in on the string when all of them are falling vertically. Since the whole system (3M) will fall faster than the 2M ball itself, then the center of gravity of the system(let say point S) will be below the center of gravity of the 2M ball ( let say point 2). But because these 2 balls are tied together with the string, then if point 2 is below point S, then the center of gravity of the 1M ball (point 1) should be the lowest one among the three, which will lead to the fact that the 1M ball is falling the fastest. This is again contradicting our assumption.
Newton’s beautiful equation
Up to the 17th century, sir Isaac Newton found the beautiful equation of gravity:
This founding made a great impact on explaining the behavior of the planets in our universe.
To this time, people believed that gravity is just a force. This force is created by two mass, which is calculated by the equation above.
Einstein’s Relativity
Newton’s law of gravity has united and found the answer to the behavior of the planets in the universe. Well, actually, for most of the planets. There is one planet which behaves differently to Newton’s and Kepler’s principle – Mercury. However, they didn’t know why and actually refused to try to find the explanation. That’s where Einstein stepped in and came up with General Relativity. So the gravity now is no longer to be a simple force, but rather be a field, which affects both space and time dimension.
Higgs Boson
Now we came to the 20th century, where things were far more complicated than before. More and more things were discovered. We found the relativity. We question the answer to our own universe, to our own old hypothesis, are they still correct, or were correct? We found out so many particles that even smaller than atoms (proton, neutron, electron), and sub-atomic particles that even smaller (quarks, leptons). The Standard model came in, string theory came in, and a lot more. However, we still don’t know why there are some sub-atomic particles that are heavier than the others. The heaviest known one is Top quarks, which weighs 172 GeV, compared to electron, which only is 0.0005 GeV. These 2 particles actually are having the same size, no size, but what makes their mass so different.
This came to the theory that we believed there is an invisible field surrounding us. Any particles which interact more with this field will have greater mass. This field is called the Higgs Field, which is named after physicist Peter Higgs. Later in 2012, people finally discovered Higgs Boson, the boson that made the Higgs Field. This founding contributed a great impact on the Standard Model. Dr. Don Lincoln in the Fermilab has a great analogy to this concept. Let’s think the field is the water. A barracuda fish, being supremely streamlined, and only interacts slightly with the field, can move through it very easily. This fish can be considered as low mass particles. On the other hand, human interacts more with the water due to our bigger surface area, will move slower in the water, and can be considered as the high mass particles. Water is made of H20 particles, the same as Higgs field is made of Higgs Boson.
How the Gravity will look like in this 21st century? Let’s wait for our scientists.
There’s a lot more to tell surrounding Gravity. But I think this post is long enough. To next time.
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