Author 193954

Stephen
Hawking
1942

English Theoretical Physicist, Cosmologist, Author, Honorary Fellow of the Royal Society of Arts, Awarded the Presidential Medal of Freedom, the highest civilian award in the United States, Lucasian Professor of Mathematics at the University of Cambridge, Research Chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario

Author Quotes

A few years ago the city council of Monza, Italy, barred pet owners from keeping goldfish in curved goldfish bowls. The measure?s sponsor explained the measure in part by saying that it is cruel to keep a fish in a bowl with curved sides because, gazing out, the fish would have a distorted view of reality.

If the theory is confirmed by observation, it will be the successful conclusion of a search going back more than 3,000 years. We will have found the grand design.

Quantum physics might seem to undermine the idea that nature is governed by laws, but that is not the case. Instead it leads us to accept a new form of determinism: given the state of a system at some time, the laws of nature determine the probabilities of various futures and pasts rather than determining the future and past with certainty.

Until the advent of modern physics it was generally thought that all knowledge of the world could be obtained through direct observation, that things are what they seem, as perceived through our senses. But the spectacular success of modern physics, which is based upon concepts such as Feynman?s that clash with everyday experience, has shown that that is not the case. The naive view of reality therefore is not compatible with modern physics.

Among the heresies was the idea that nature follows laws, because this conflicts with God?s omnipotence. Interestingly, Pope John was killed by the effects of the law of gravity a few months later when the roof of his palace fell in on him.

Ignorance of nature?s ways led people in ancient times to invent gods to lord it over every aspect of human life.

Quantum physics tells us that no matter how thorough our observation of the present, the (unobserved) past, like the future, is indefinite and exists only as a spectrum of possibilities. The universe, according to quantum physics, has no single past, or history. The fact that the past takes no definite form means that observations you make on a system in the present affect its past. That is underlined rather dramatically by a type of experiment thought up by physicist John Wheeler, called a delayed-choice experiment. Schematically, a delayed-choice experiment is like the double-slit experiment we just described, in which you have the option of observing the path that the particle takes, except in the delayed-choice experiment you postpone your decision about whether or not to observe the path until just before the particle hits the detection screen. Delayed-choice experiments result in data identical to those we get when we choose to observe (or not observe) the which-path information by watching the slits themselves. But in this case the path each particle takes?that is, its past?is determined long after it passed through the slits and presumably had to decide whether to travel through just one slit, which does not produce interference, or both slits, which does. Wheeler even considered a cosmic version of the experiment, in which the particles involved are photons emitted by powerful quasars billions of light-years away. Such light could be split into two paths and refocused toward earth by the gravitational lensing of an intervening galaxy. Though the experiment is beyond the reach of current technology, if we could collect enough photons from this light, they ought to form an interference pattern. Yet if we place a device to measure which-path information shortly before detection, that pattern should disappear. The choice whether to take one or both paths in this case would have been made billions of years ago, before the earth or perhaps even our sun was formed, and yet with our observation in the laboratory we will be affecting that choice. In

We are the product of quantum fluctuations in the very early universe. If one were religious, one could say that God really does play dice.

Anaximander, a friend and possibly a student of Thales, argued that since human infants are helpless at birth, if the first human had somehow appeared on earth as an infant, it would not have survived. In what may have been humanity's first inkling of evolution, people, Anaximander reasoned, must therefore have evolved from other animals whose young are hardier.

In 1992 came the first confirmed observation of a planet orbiting a star other than our sun.

Recent experiments in neuroscience support the view that it is our physical brain, following the known laws of science, that determines our actions, and not some agency that exists outside those laws. For example, a study of patients undergoing awake brain surgery found that by electrically stimulating the appropriate regions of the brain, one could create in the patient the desire to move the hand, arm or foot, or to move the lips and talk. It is hard to imagine how free will can operate if our behaviour is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.

We believe human begins have existed for only a small fraction of cosmic history, because human race has been improving so rapidly in knowledge and technology that if people had been around for millions of years, the human race would be much further along in its mastery.

As a result, in more than three dimensions the sun would not be able to exist in a stable state with its internal pressure balancing the pull of gravity. It would either fall apart or collapse to form a black hole, either of which could ruin your day.

In fact, according to quantum physics, each particle has some probability of being found anywhere in the universe.

Single photons are not usually evident, but in the laboratory we can produce a beam of light so faint that it consists of a stream of single photons, which we can detect as individuals just as we can detect individual electrons or buckyballs. And we can repeat Young?s experiment employing a beam sufficiently sparse that the photons reach the barrier one at a time, with a few seconds between each arrival. If we do that, and then add up all the individual impacts recorded by the screen on the far side of the barrier, we find that together they build up the same interference pattern that would be built up if we performed the Davisson-Germer experiment but fired the electrons (or buckyballs) at the screen one at a time. To physicists, that was a startling revelation: If individual particles interfere with themselves, then the wave nature of light is the property not just of a beam or of a large collection of photons but of the individual particles.

We create history by our observation, rather than history creating us.

Because gravity shapes space and time, it allows space time to be locally stable but globally unstable. On the scale of the entire universe, the positive energy of the matter can be balanced by the negative gravitational energy, and so there is no restriction on the creation of whole universes. Because there is a law like gravity, the universe can and will create itself from nothing.

In fact, if general relativity were not taken into account in GPS satellite navigation systems, errors in global positions would accumulate at a rate of about ten kilometers each day!

So look carefully at the map of the microwave sky. It is the blueprint for all the structure in the universe. We are the product of quantum fluctuations in the very early universe. If one were religious, one could say that God really does play dice.

We create models in science, but also in everyday life. Model-dependent realism applies not only to scientific models, and mental models that we create all know, conscious or subconscious level, to interpret and understand the world every day. We cannot eliminate observer - ourselves - from our perception of the world, obtained by processing sensory perception and the way we think and rational. Our perception - and hence the observations which underpins our theories - not directly, but is adjusted by a kind of lens, interpretive structure of the human brain.

Bodies such as stars or black holes cannot just appear out of nothing. But a whole universe can.

In modern science laws of nature are usually phrased in mathematics. They can be either exact or approximate, but they must have been observed to hold without exception?if not universally, then at least under a stipulated set of conditions. For

Some people make a great mystery of this idea, sometimes called the multiverse concept, but these are just different expressions of the Feynman sum over histories.

Why is there something rather than nothing? Why do we exist? Why this particular set of laws and not some other? This is the Ultimate Question of Life, the Universe and Everything. We shall attempt to answer it in this book. Unlike the answer given in The Hitchhiker?s Guide to the Galaxy, ours won?t be simply ?42?.

Both observer and observed are parts of the world that has an objective existence, and any distinction between them has no meaningful significance. In other words, if you see a herd of zebras fighting for a spot in the parking garage, it is because there really is a herd of zebras fighting for a spot in the parking garage.

Author Picture
First Name
Stephen
Last Name
Hawking
Birth Date
1942
Bio

English Theoretical Physicist, Cosmologist, Author, Honorary Fellow of the Royal Society of Arts, Awarded the Presidential Medal of Freedom, the highest civilian award in the United States, Lucasian Professor of Mathematics at the University of Cambridge, Research Chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario