Newton’s Clockwork Vision of the Universe and Its Relation to Gravity Force

FROM THE LECTURE SERIES: THE JOY OF SCIENCE

By Robert M. Hazen, Ph.D., George Mason University

As the history of science reveals, the clockwork vision correlates the universe to a mechanical clock. It goes on ticking with its gears controlled by the laws of physics, making every behavior of the device predictable. Isaac Newton also followed this idea after he developed his laws of motion. What were his findings?

An illustration of a clock in the galaxy on a cosmic background.
A clockwork universe raised many theological debates in centuries past. (Image: agsandrew/Shutterstock)

The Difference Between Mass and Weight

Recognizing the fundamental difference between weight and mass is very significant because these terms are often interchanged. Weight is the gravitational force, and it varies from place to place on the Earth’s surface. It’s different on the Earth than the Moon. 

Mass, however, is the amount of stuff or the number of atoms, and it doesn’t vary from one place to another. The mass of an object is constant even though the weight may vary depending on where the object is.

How To Calculate Weight on Earth 

An illustration of the Moon orbiting the Earth
Newton proved that weight is different from mass. (Image: canbedone/Shutterstock)

There are two ways to calculate the weight, for example, of a person, on Earth. One, using the second law of motion, force equals mass times acceleration. A 60-kilogram person on Earth equals 588 newtons according to this equation. 

The other way is to do the exact same calculation by plugging into the expression for gravity, force equals capital G, the mass of the Earth, times the mass of the object divided by r2.  This equation also provides the same answer which is 588 newtons for a 60-kilogram person.

This is a transcript from the video series The Joy of Science. Watch it now, on The Great Courses Plus.

Gravitational Constant and Weight on the Moon 

Objects weigh less on the Moon because the Moon is a less massive object than the Earth. To determine what is the weight of a 60-kilogram object on the Moon’s surface some variations like the radius and the mass of the Moon are needed.

After plugging the numbers into the same equation for gravity—force equals the mass of the Moon times the mass of the individual divided by the radius of the Moon squared—the answer will be 95 newtons. Of course, 95 newtons is only one-sixth of the weight of an object on the Earth’s surface. 

A diagram of the Moon and the Earth showing gravity’s impact on scale measurements.
A person can jump higher on the moon because they weigh less there. (Image: Vectormine/Shutterstock)

That is why people can skip and jump really high on the Moon, and everything looks like it is taking place in slow motion because the force of gravity is so much less. And because the acceleration on the Moon is one-sixth the acceleration on the Earth, people jump and come down very slowly. 

A golf ball could be hit a lot farther on the Moon, largely because of the difference in the gravitational acceleration at the surface of the Moon, also because there is no atmosphere, so there is no wind resistance to that golf ball.

Learn more about Newton’s laws of motion.

Newton’s Clockwork Vision of the Universe 

Newton’s universal laws of motion and gravity reveal the deep and pervasive order in the natural world. One set of laws applies everywhere in the universe (on the surface of the Earth, Moon, planets, stars, etc.). They provide a framework by which many other phenomena can be more understandable, and they also provide unity to the understanding of the natural world. 

There is nothing special about the surface of the Earth in terms of the laws of motion and in terms of the forces involved. Perhaps Newton’s greatest legacy is the view of the universe as a place of deep mathematical order, a clockwork universe. The mechanisms can be deduced through observation and analysis of the natural world.

Learn more about the fact of evolution—the fossil record.

Cause and Effect or Law and Order? 

The optimistic view that humans could deduce the order of the natural world had a significant trickle-down effect in other human endeavors. During the enlightenment, which was about a century after Newton, scholars advocated this rationalist approach to all different kinds of human endeavor, like economics, education, political systems, and the law. 

It was felt that there must be universal laws that dictated all kinds of activities that humans undertook. Indeed, Newton’s first firm statement of this cause and effect relationship in the natural world seems to have pervaded the legal system today. If something bad happens, there must be a specific cause.  

But indeed, cause and effect have become part of people’s thinking about the universe. The drafters of the United States Constitution and the Bill of Rights firmly believed that there was a rational system of government that could be derived, and there were laws and order to the political system as well. The Bill of Rights and the Constitution thus reflect this optimistic view of order—the attempt that humans could find that order, and in fact run their lives according to those laws.

Learn more about Charles Darwin and the theory of natural selection.

Newton’s Laws and the Theological Debates 

Newton’s laws even contributed to theological debates. Some followers of Newton, notably the French mathematician Pierre Simon Laplace, who lived from 1749 to 1827, speculated that since the laws of motion are exact and predict the motions of every possible particle under every kind of force and interaction, hence, the future of every particle in the universe was preordained, and this led to a very interesting theological speculation.

The speculation that, since everything in the universe is preordained, there is no such thing as free will, and people actually act out their lives. Accordingly, every event in people’s lives was something that was preordained just by the way particles were set into motion billions of years ago before anyone had ever heard of Isaac Newton and his laws of motion. But is that possible?

Common Questions about Newton’s Clockwork Vision of the Universe

Q: What is the theological debate according to the clockwork vision?

Since clockwork vision was deduced through gravity force laws, the debate speculates that every event in the world is preordained and that all particles were set into motion billions of years ago before gravity was discovered.

Q: What is the difference between mass and weight?

Mass is a constant that is not changed according to where it is. However, weight varies from one place to another. These variables help in the comprehension of concepts such as gravity force and its equation.

Q: Why is acceleration different on the Earth than on the Moon?

According to gravity force and Newton’s law, more mass means more force. Since the Moon is less massive than the Earth, its acceleration is only one-sixth of the Earth’s.

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