Brief Answers to the Big Questions

by Stephen Hawking

Religion was an early attempt to answer the questions we all ask: why are we here, where did we come from? Long ago, the answer was almost always the same: gods made everything.

At first, it seems a baffling problem – after all, in our daily lives things don’t just materialise out of the blue. You can’t just click

your fingers and summon up

a cup of coffee when you feel like one. You have to make it out of other stuff like coffee beans, water and perhaps some milk and sugar. But travel down into this coffee cup – through the milk particles, down to the atomic level and right down to the sub-atomic level, and...

At least, for a short while. That’s because, at this scale, particles such as protons behave according to the laws of...

Instead, they were dynamical quantities that were shaped by the matter and energy in the universe. They were defined only within the universe, so it made no sense to talk of a time before the universe began. It would be like asking for a point south of the South

Pole. It is not defined.

If stars

had been radiating for an infinite time, they would have heated up the universe until it reached their own temperature. Even at night, the whole sky would be as bright as the Sun, because every line of sight would have ended either on a star or on a cloud of dust that had been heated up until it was as hot as the stars.

we have all made, that the sky at night is dark, is very important. It implies that the universe cannot have existed for ever, in the state we see today. Something must have happened in th...

metaphysics

When the universe is big, there are a very large number of rolls of the dice, and the results average out to something one can predict. But when the universe is very small, near the Big Bang, there are only a small

number of rolls of the dice, and the Uncertainty Principle is very important.

retrodict

gravitation obeying the inverse square law, as discovered by Robert Hooke in 1665 and elaborated on by Isaac Newton.

mammals already contained their versions of the essential organs we have. All that was required to evolve from early mammals to humans was a bit of fine-tuning.

Some people would use the term ‘evolution’ only for

the internally transmitted genetic material and would object to it being applied to information handed down externally. But I think that is too narrow a view. We are more than just our genes. We may be no stronger or inherently more intelligent than our caveman ancestors. But what distinguishes us from them is the knowledge that we have accumulated over the last 10,000 years, and particularly over the last 300. I think it is legitimate to take a broader view and include externally transmitted information, as well as DNA, in the evolution of the human race.

It might be possible to use genetic engineering to make DNA-based life survive indefinitely, or at least for

100,000 years. But an easier way, which is almost within our capabilities already, would be to send machines. These could be designed to last long enough for interstellar travel. When they arrived at a new star, they could land on a suitable planet and mine material to produce more machines, which could be sent on to yet more stars. These machines

would be a new form of life, based on mechanical and electronic components rather than macromolecules. They could eventually replace DNA-based life, just as DN...

pantheon

In physics the smallest doll is called the Planck length and is a millimetre divided by a 100,000 billion billion

billion. We are not about to build particle accelerators that can probe to distances that small. They would have to be larger than the solar system and they are not likely to be approved in the present financial climate.

Whereas the short-term impact of AI depends on who controls it, the long-term impact depends on whether it can be controlled at all.

Intelligence is characterised as the ability to adapt to change. Human intelligence is the result of generations of natural selection of those with the ability to adapt to changed circumstances. We must not fear change. We need to make it work to our advantage.

People asked a computer, ‘Is there a God?’ And the computer said, ‘There is now,’ and fused the plug.

ingenuity,

Einstein had the ability to look beyond the surface to reveal the underlying structure. He was undaunted by common sense, the idea that things must be the way they seemed. He had the courage to pursue ideas that seemed absurd to others. And this set him free to be ingenious, a genius of his time and every other. A key element for Einstein was imagination. Many of his discoveries came from his ability to reimagine the universe through thought experiments. At the age of sixteen, when he visualised riding on a beam of light, he realised that from this vantage light would appear as a frozen wave. That image ultimately led to the theory of special relativity.

He opened my eyes to maths as the blueprint of the universe itself. If you look behind every exceptional person there is an exceptional teacher. When each of us thinks about what we can do in life, chances are we can do it because of a teacher.

Most people respond to a qualitative, rather than a quantitative,

understanding, without the need for complicated equations.