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Explanation of modern views of the Force of Gravity - Succeed in Physical Science. Also refer to physics, Newton, Einstein, forces, Relativity, Quantum Physics, curvature of space, wave, particle, duality, elevator, acceleration, graviton, Ron Kurtus, School for Champions. Copyright © Restrictions

Modern Views of the Force of Gravity

by Ron Kurtus (revised 2 September 2007)

Isaac Newton determined the laws of gravity around 1680. Albert Einstein reformulated the laws to fit his General Theory of Relativity. He said gravity was similar to acceleration and that is it caused by a curvature of space. Recent theories about gravitation state that it has wavelength and is a particle.

Questions you may have include:

• How is gravity similar to acceleration?
• What causes curvature in space?
• How can gravity be a wave and a particle?

This lesson will answer those questions. There is a mini-quiz near the end of the lesson.

Similar to acceleration

Physicist Albert Einstein examined gravitation in his study of the General Theory of Relativity. He noticed that if you are in an elevator that was going up, you felt heavier due to the acceleration of the elevator's motion.

Einstein concluded that since the force from acceleration had the same effect as the force caused by gravity, there must be some mathematical relationship between the two. In fact, he said that gravity was actually caused by acceleration.

That idea is not too clear, since when the elevator is accelerating upward, it is directly pushing on you. On the other hand, gravity is a force that acts at a distance through some force field or perhaps unknown means. Perhaps gravity is similar to acceleration, but it is not caused but it.

This effect was the starting point in the development of an explanation of gravitation. Einstein considered the relationship of moving objects, their acceleration, and the apparent effects they had. This led him to the conclusion that space was curved.

Curvature of space

Einstein postulated that the presence of matter distorts the space around it.

This can be explained by picturing space as a grid of lines. Without matter, space would be a perfect grid of parallel lines. An object would move in a straight line through space.

The presence of another mass of matter would distort the lines, drawing some toward it. Thus a moving object would no longer travel in a straight line. Instead, it would curve toward the other object, appearing to be attracted to it. What this theory does is says that gravitation—the attraction of an object toward another—was not caused by the apparent force of gravity between masses. Instead, it was simply a property of space.

This is a pretty abstract concept, but Einstein demonstrated it with highly complex mathematical equations. Many scientists accept this concept of the curvature of space as an explanation of gravitation.

Particle and waves

The problem with the General Theory of Relativity's explanation of gravitation as being caused by the curvature of space is that it did not follow the rules of Quantum Mechanics or Quantum Physics—the study of matter at extremely shorts distances. Thus, scientists predicted that a gravitational field would exhibit wavelengths, similar to electromagnetic waves. Using highly sensitive instruments, experiments were made to verify that gravity is indeed a waveform of some sort.

To follow the wave-particle duality in Quantum Physics, it was also predicted that gravity consists of particles called gravitons. This is similar to the theory that light is not only a waveform, but also consists of particles called photons. Electrons are also viewed as both particles and waves.

This view of gravity being a wave or particle goes back to the idea that matter exhibits gravitation and that there truly is a force of gravity. (Nobody said that Physical Science would be easy and that everything was known or explained.)

Summary

Einstein's laws of gravity fit his General Theory of Relativity. He said gravity was similar to acceleration and is caused by a curvature of space. Recent theories about gravity state that it has wavelength and is a particle.

Answers to Readers' Questions

Think of all the possibilities

Resources

The following resources provide information on this subject:

Websites

Physical Science Resources

Books

Top-rated books on Simple Gravity Science

Top-rated books on Advanced Gravity Physics

Miscellaneous

Mini-quiz to check your understanding

1. What happens when a roller coaster suddenly goes downhill?

2. According to Einstein, what happens as you increase the mass of an object?

3. How can waves be particles at the same time?

If you got all three correct, you are on your way to becoming a Champion in Physical Science. If you had problems, you had better look over the material again.

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Modern Views of the Force of Gravity