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Posted 24 May 2008

Perceptions of Reality and Our View of the Universe

by Frikkie de Bruyn


By deepening our understanding of the true nature of physical reality,
we profoundly reconfigure our sense of ourselves and our experience
of the universe
.........................................................-Brian Greene


1. Introduction

In a conversation with a fellow amateur astronomer I asked the question: “What is reality?” The response was very quick: “Reality is what we see”. I took a prism and showed him the wavelengths of visible light separated in different wavelengths and colour. Did this change his perception of reality? This might have changed his view or it might not. But what this clearly illustrated is that there is more to reality than we can perceive with our senses. The same is of course true of our view of the universe. Scientists are only beginning to piece together the details of galaxy formation, the true nature of the contents of neutron stars, even the source of the most powerful events in the universe that caused the emission of gamma rays remains a mystery. The question is: “Will we ever learn all the details?” What impact will that have on our everyday lives? Should we not accept that the details will be revealed to us by our senses, nothing else? The problem is that our senses mislead us often. The story that science tells us, most of us will agree, is very different from what our senses reveal to us. Einstein’s revelations about the true nature of space and time have shaken the very basis of our understanding of reality. Spacetime became the player in the shaping of the universe. Einstein did not admit it, but his general theory of relativity equations revealed to us some of the nature of the birth and evolution of our universe. Let us look at some of the major changes science brought to our understanding of the universe.

2. Gallileo

Galileo is mostly remembered for two reasons, both are wrong. He did not invent the telescope as generally believed. It was apparently invented by lens makers in Holland about 1608. Nor was Galileo condemned by the inquisition for believing that the Earth moved around the sun. Why were Galileo’s ideas important for our views of the universe? He seems to have adopted the Copernican model of the heliocentric model that the Earth moved around the sun. Galileo used the telescope to systematically observe the sky and apply his observations to the theoretical problem of the day, the place of the earth in our solar system. He applied a new method of finding out facts, the scientific method. He discovered that the moon was not perfect as previously thought. It had mountains and valleys and he used the shadows to calculate the heights of the mountains. He discovered that the Milky Way was made up of stars which couldn’t be seen with the unaided eye. His most spectacular discovery, however, was the discovery of the moons of Jupiter. Galileo was condemned by the Vatican for promoting the ideas of Copernicus and sentenced to life imprisonment where he continued to use his telescope. Galileo was accused of promoting ideas in conflict with the scriptures, but he phrased his own believes as follows: “The Bible tells us how to go to heaven, not how the heavens go.” His trial was basically about scientific observation believed to be in conflict with faith. This tragic error was rectified by Pope John Paul II and Galileo was found not guilty. Galileo’s trial was really about the birth of modern science.

3. Newton and gravity

Isaac Newton is often erroneously described as the discoverer of gravity. Does this mean gravity did not exist before Newton? Rather, it would be correct to say Newton understood some of the ways gravity worked. He discovered the laws of mutual gravitation, the inverse square law of gravity and astronomers use his laws to describe the universe. His laws were amazingly successful in describing the heavens and the movement of planets and stars. Edmund Halley used Newton’s laws to calculate the orbits of comets, one of them now known as Comet Halley. During his life Newton invented calculus, developed three laws of motion and discovered the three laws of mutual gravitation. Newton extended our perceptions of how the universe works, how the planets revolve around the sun and how to calculate the apparent force of attraction of gravity in terms of the distance between bodies. But some of Newton’s laws were in conflict with experiments by Maxwell and the velocity of light. After almost two centuries Albert Einstein showed that Newton’s laws were only approximately correct and could be seriously wrong in special circumstances. Einstein did not replace Newton’s laws but extended our understanding of reality and the universe.

4. Einstein’s relativity theories

We have seen above that in Einstein’s general relativity theory space and time form an active unity, spacetime. In the pre-Einstein way of thinking space and time were separate, they were out there and they were never changing. Accordingly the time on Jupiter would have been the same as on Earth. Einstein rejected this notion and made spacetime an active player in the evolution of the universe. This enabled him to correctly describe the effects of gravity as the curvature of spacetime. This was proved to be correct in hundreds of experiments. This had far reaching consequences for our perception of time. Time was not the same for everyone. Each person has his/her own time. Our perception of reality has been changed accordingly. The now is different for everyone. Let us take as an example one of the Pioneer spacecraft (there are two) which is currently leaving the solar system. If there could be an astronought on board and I could compare time with her I would find that her time passes slower than mine. It might sound crazy, but please bear with me. If the astronought could have a very powerful telescope to see events unfolding on Earth she would see that Earth has advanced quicker in time than she has. Her twin sister on Earth will look considerably older than she (the astronought) is. What does it tell us about the flow of time? We are in for a rude shock. The flow of time is an illusion. The past exist in our memories only, but the past is really part of my now. Einstein reconciled what we call “time” with the laws of physics since the flow of time has no place in physics. In short; time does not exist!

5. The quantum revolution

Quantum mechanics simply tells us that reality is very different from what we observe with our senses. I shall shortly describe how quantum fluctuations drastically changed our views of reality. In the pre-quantum and pre-Higgs physics (it is believed that the Higgs field permeating all of space give mass to matter), we regard a region of space as being empty if it contains no particles and the value of every field was uniformly zero. If the value of a field is zero then it cannot change and we know both the value and the rate of change of the field (zero) at the same time. But this clashes with the most basic tenet of quantum mechanics, the uncertainty principle. According to the uncertainty principle it is impossible to know both the rate of change of a field and its value. If the field has a definite value then the rate of change will be indefinite. A vacuum field is seething with quantum fluctuations which can also be described as virtual particles flashing in existence and annihilating within the time prescribed by the uncertainty principle. In the Casimir experiment it is proved that if you place two ordinary metal plates extremely close together in an otherwise empty region, there will be fewer quantum fluctuations between he plates and the plates will be forced together. There are many other examples of how the quantum revolution changed our views of reality and the universe such as quantum entanglement, but this requires another article.

Frikkie de Bruyn


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Recommended for further reading:

Technical but very good:
Wald, Robert M. 1984, General Relativity, University of Chicago Press, Chicago.
Less technical highly recommended:
Penrose, Roger R. 2004, The Road to Reality, A Complete Guide to the Laws of the Universe, Random House, London.
Barbour, J.B. 1992, Time and the Interpretation of Quantum Gravity, Syracuse University.
Gell-Mann, M 1994, The Quark and the Jaguar: Ad ventures in the Simple and the Complex, W.H. Freeman, New York.
Greene, B. 2004, The Fabric of the Cosmos, Space, Time, and the Texture of Reality, Penguin Books, London
Hawking, S.W. and Penrose, R. The Nature of Space and Time, Princeton University Press.

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