Quotes from Stephen Hawking

If one believed that the universe had a beginning, the obvious question was what happened before the beginning? What was God doing before He made the world? Was He preparing Hell for people who asked such questions?

After my expectations had been reduced to zero, every new day became a bonus, and I began to appreciate everything I did have. While there's life, there is hope.

In space, no one can you scream; an in a black hole, no one can see you disappear

All the known particles in the universe can be divided into two groups: particles of spin ½, which make up the matter in the universe, and particles of spin 0, 1, and 2, which, as we shall see, give rise to forces between the matter particles.

The Ionian idea that the universe is not human-centered was a milestone

model-dependent realism. It is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.

There has been relatively little change in human DNA in the last 10,000 years. But it is likely that we will be able to redesign it completely in the next thousand. Of course, many people will say that genetic engineering on humans should be banned. But I rather doubt that they will be able to prevent it. Genetic engineering on plants and animals will be allowed for economic reasons, and someone is bound to try it on humans.

The brightest boys did mathematics and physics. The less bright did biology.

The naive view of reality therefore is not compatible with modern physics. To deal with such paradoxes we shall adopt an approach that we call model-dependent realism. It is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.

If time travel were possible we'd be inundated with tourist from the future.

We see the unity, and not the divisions. It is such a simple image with a compelling message; one planet, one human race.

God not only plays dice, He also sometimes throw the dice where they cannot be seen.

N VIKING MYTHOLOGY, Skoll and Hati chase the sun and the moon. When the wolves catch either one, there is an eclipse. When this happens, the people on earth rush to rescue the sun or moon by making as much noise as they can in hopes of scaring off the wolves.

If we do discover a complete theory, it should in time be understandable in broad principle by everyone, not just a few scientists. Then we shall all, philosophers, scientists, and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason—for then we would know the mind of God.

Despite some early success predicting the motion of celestial bodies, most events in nature appeared to our ancestors to be impossible to predict. Volcanoes, earthquakes, storms, pestilences, and ingrown toenails all seemed to occur without obvious cause or pattern.

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.

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.

Anaximander (ca. 610 BC–ca. 546 BC), 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

One could define God as the embodiment of the laws of nature.

To understand the universe at the deepest level, we need to know not only how the universe behaves, but why. 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.

The microwave background indicated that the universe had had a hot, dense stage in the past.

the statement "All uranium-235 spheres are less than a mile in diameter" could be thought of as a law of nature because, according to what we know about nuclear physics, once a sphere of uranium-235 grew to a diameter greater than about six inches, it would demolish itself in a nuclear explosion. Hence we can be sure that such spheres do not exist. (Nor would it be a good idea to try to make one!)

When we invented fire, we messed up repeatedly, then invented the fire extinguisher. With more powerful technologies such as nuclear weapons, synthetic biology and strong artificial intelligence, we should instead plan ahead and aim to get things right the first time, because it may be the only chance we will get. Our future is a race between the growing power of our technology and the wisdom with which we use it. Let's make sure that wisdom wins.

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 behavior is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.