Characteristics of Physical Law


Despite numerous limitations, we human beings are able enough to study as well as appreciate the grandeur of the universe. Our great journey of determining scientific laws began as we understood the regular repetitions of the day and night, the annual cycle of seasons, the eclipses, the tides, the volcanoes, the rainbow and so on.


What is scientific law?

A scientific law is verbal or mathematical explanation that describes some phenomenon of the natural world. For example, Newton's law of gravity, which states that every particle attracts every other particle in the universe with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. But the law itself does not explain why the phenomenon exists or what causes it: that is really the job of theory, in this case, Einstein's theory of general relativity.

The scientific law is factual and should not be confused with logical truth. For example, "boiling point of water is 100 degrees celsius" is a law whereas "every number has a double" is logical truth and not really a law.


Constant over space and time

The same laws which apply here on earth also apply to the rest of the universe. For example, Galileo's law of falling bodies was tested on the moon by astronaut David Scott in 1971.


This is simple and yet beautiful truth, that the laws of nature are universally valid. There are no laws of nature that hold just for the planet earth or the Andromeda Galaxy, for that matter.

In addition, the laws of nature do not change as time progresses. There is a joke which goes something like this, "Before Newton discovered gravity, all things could fly." That is so not the case; there are no laws of nature that hold just for the eighteenth century or just for the Mesozoic Era.



Same for animate and inanimate

The laws are same for living beings and for inanimate objects. There is no evidence yet that what goes on in living creatures is necessarily different, so far as the physical laws are concerned, from what goes on in non-living things.

For example, conservation of angular momentum is a fundamental law of nature. A rotating ballerina spins faster when drawing her arms in.

how are physical laws symmetrical?

Similarly, the earth and other planets revolving around the sun obey the law of conservation of angular momentum, which is why, when a planet is nearer to the Sun, the orbital speed increases and when it is farther away, it slows down.


Simple in nature

Eminent kiwi physicist Ernest Rutherford used to say, "it should be possible to explain the laws of physics to a barmaid." But even though the laws themselves are so simple, their implications are far and wide.

For example, Newton's third law of motion is simply, "for every action there is equal and opposite reaction", and yet it is noticeable in many instances of life such as in walking, swimming, recoiling of gun, and most importantly, rocket propulsion.

how are physical laws symmetrical?

Similarly, Newton's second law of motion is just, F=ma, but it made possible the industrial revolution. Steam engines, locomotives, factories, machines, all of it due to the mechanics set into motion by the second law of motion.


Same in uniform motion

If we have an experiment working in a certain way and then take the same apparatus, put it in a car, and move the whole car, plus all the relevant surroundings, at a uniform velocity in a straight line, then so far as the phenomena inside the car are concerned, there is no difference.


Unification of laws

Scottish physicist James Clerk Maxwell took a set of known experimental laws such as Faraday's Law, Ampere's Law and unified them into a symmetric coherent set of equations known as Maxwell's equations.

how are physical laws symmetrical?

Maxwell's equations are also laws just like the law of gravity. They govern the behavior of electric and magnetic fields. Also, light itself is an electromagnetic wave. Therefore, Maxwell's equations have in a way unified three separate phenomena, electricity, magnetism and optics, into one.

A similar type of unification occurred in the early part of the 20th century. The laws of conservation of energy and conservation of total mass were proven to be equivalent by German physicist Albert Einstein in a simple equation, E=mc^2.


These unifications are possible because the laws of physics are symmetrical in nature. Two or more distinctly appearing natural phenomena appear to be governed by just one simple law. Thus, one day, we may be able to find an ultimate law of physics that may explain everything.

Renowned American physicist Richard Feynman had famously said, "God is always invented to explain those things that you do not understand."

Throughout history, man has credited god for this or that phenomena. For example, early Greeks believed that lightning was a weapon of Zeus. Now, when you finally discover how something works, you get some laws which you're taking away from god; you don't need god anymore.

Thus, "what one man calls god, another calls the laws of physics," or in other words, to have an understanding of the physical laws is in a way a liberation from all superstition.

How To Study Physics By Using Feynman Technique

how to learn by feynman technique

Richard Feynman was one of the world’s greatest scientists who won a nobel prize for physics in 1965. But we recognize him more as an outstanding teacher, a story-teller and an everyday joker whose life, was a combination of his intelligence, curiosity and uncertainty.

Feynman was once asked in an interview whether an ordinary person could understand physics like him. After a brief pause, "of course!", he replied candidly. "I was an ordinary person who studied hard."

In this post, you will learn to study physics by using the Feynman Technique, a method involving four easy steps, which was designed to help you understand concepts you don't get and to remember stuff you've already learned.

1. Write

how to learn by feynman technique

This is a no-brainer. Always write down everything you know about the topic on a notebook page. Add examples and illustrations in your notes whenever possible.

Why is it important to write? Because writing anything down makes us remember it better. This is also the reason why many life coaches advise to pen down our goals.


2. Explain

Describe whatever you have learned to an empty room. This step will not only test memorization but also help you to become a better teacher.

how to learn by feynman technique

Yes, many of you may not want to go into the teaching profession but it is a good practice to convey your learning in loud words. Remember, teaching is a powerful tool to learning.


3. Analyze

There is a famous saying which many attribute to Feynman, "If you cannot explain it simply, you do not understand it", which is fairly obvious.

how to learn by feynman technique

Did you teach it well? Where is the gap in your understanding? Identify it. Then, revisit your notes for revision.

Revision often increases your confidence because the gap in your understanding is reduced. You may even want to rewrite your notes in a more simple language than before.


4. Repeat

Because of revision, you should have a better grasp of the subject. So gather one of your friends and explain the topic once again, to him/her. This step is powerful because when one teaches, two learn.

how to learn by feynman technique

At the end, take feedback from your friend as that might help in understanding any remaining gaps. Did you know that Professor Walter Lewin, famous for his physics videos on YouTube, used to teach at least five times to an empty hall, before actually taking the class?


Summing up

Feynman had once said, "I don't know what's the matter with people: they don't learn by understanding; they learn by some other way, by rote or something. Their knowledge is so fragile!"

But if you follow what is known as the Feynman Technique, as described here, you will be able to learn more efficiently and firmly. It is a tried and tested method so please share this post with fellow students.

Who was Carl Sagan?

Carl Sagan Biography For Teenagers

As a scientist, Carl Sagan contributed enormously to our knowledge of the solar system. He correctly predicted the existence of methane lakes on Saturn's largest moon Titan. When other astronomers had imagined Venus to be a balmy paradise he showed it to be dry, thick and unpleasantly hot. Carl went on to propose that the atmosphere of the early earth must have contained powerful greenhouse gases.


When she returned, all of Carl's enthusiasm turned into utter disappointment. She had with her a book on the Hollywood stars, wait what, those weren't the kind of stars that concerned an astronomer.

The librarian, a little embarrassed, shifted her attention to a different bookshelf. After searching for a while, she brought with her the correct book, titled, "secrets of the stars". She handed it to the young astronomer. This incident made a deep and lasting impression on a young Carl Sagan.


Career at NASA

Carl Sagan attended the University of Chicago where he came under the guidance of famous physicists such as Enrico Fermi and Edward Teller. As an undergraduate he worked for geneticist H.J. Muller and wrote a thesis on the origins of life.

Carl Sagan Biography For Teenagers

Carl Sagan went on to earn a masters in physics in 1956, before earning a PhD degree in 1960.

Then he became a visiting scientist to NASA's Jet Propulsion Laboratory where he contributed to the making of the first Mariner orbiter mission to Venus.

The Mariner Orbiter confirmed his conclusions on the surface conditions on Venus in 1962. He also worked closely with NASA for the successful landing of man on the moon in 1969.


Next, he worked with NASA for the Viking space program which  was set up to explore the habitat and environment of planet Mars. For the first time in human history, a man-made object had landed on an alien world.

Carl Sagan Biography For Teenagers
viking on mars, 1976

However, the viking landing did not receive attention it deserved. The general public was widely unaware of a significant success in the field of space exploration. Was it not important to people? Was it not worth their time? These questions began to haunt Carl's imagination.

Therefore, just two years later in 1978, Carl Sagan began to work for a new TV show, Cosmos: a personal voyage. Its objective was to narrate to people the story of cosmic evolution, sciences and civilization. In 1980, the first episode of Cosmos was aired and became an instant hit.


Cosmos

Using the word "cosmos" rather than the word universe implies viewing the universe as a complex and orderly system; the opposite of chaos. Nobody had ever explained space, in all its bewildering glory, as well as Sagan did.

Carl Sagan Biography For Teenagers
ship of the imagination

Cosmos was seen in over 60 countries by more than 500 million people. It was the biggest show of the eighties.

In the fifth episode of the series, Sagan explained the kind of experiments performed by viking on the surface of planet Mars. The episode ends with the possibility of the colonization of Mars which became inspiration for the likes of Elon Musk.


During the same time, he was also working with NASA for the voyager space program whose mission was to investigate the outskirts of the solar system for signs of life.

Voyager 1, which had completed its primary mission and was leaving the Solar System, was commanded by NASA to turn its camera around and take one last photograph of Earth across a great expanse of space, at the request of Carl Sagan.

This picture is called The Pale Blue Dot.

Carl Sagan Biography For Teenagers
consider again that dot

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light.

The earth is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.


People's Astronomer

Through his appearances on TV and eloquent writings, he has shown many a times how space humbles as well as lifts. He brought astronomy into our living rooms.

Today, the word "cosmos" is on everyone's lips thanks to Carl Sagan. He made astronomy more accessible to people by popularizing it.

Carl Sagan Biography For Teenagers

In fact, Carl Sagan turned astronomy into a deep spiritual experience.

That we are not different from space but a little part of it, made from it. The nitrogen in our DNA, calcium in our teeth and iron in our blood were first forged in the interiors of the dying stars. That we are the star-stuff contemplating the stars is well and truly a great spiritual realization.

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