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Source: A Brief History of Time

From the lecture Life in the Universe http://hawking.org.uk/index.php?option=com_content&view=article&id=65 (1996)

Also quoted in &quot;Stephen Hawking warns over making contact with aliens&quot; http://news.bbc.co.uk/2/hi/uk_news/8642558.stm at BBC News (25 April 2010). <br class="br">Into The Universe with Stephen Hawking (2010) <br class="br">Context: If aliens visit us, the outcome would be much as when Columbus landed in America, which didn&#x27;t turn out well for the Native Americans. … We only have to look at ourselves to see how intelligent life might develop into something we wouldn&#x27;t want to meet.

Foreword to The Physics of Star Trek by Lawrence Krauss (2007), p. xiii http://books.google.com/books?id=NEhSpZFWiBMC&amp;lpg=PP1&amp;pg=PR13#v=onepage&amp;q&amp;f=false

During the same 1994 exchange with Penrose as the previous quote, transcribed in The Nature of Space and Time (1996) by Stephen Hawking and Roger Penrose, p. 26 http://books.google.com/books?id=LstaQTXP65cC&amp;lpg=PA26&amp;dq=hawking%20%22where%20they%20can&#x27;t%20be%20seen%22&amp;pg=PA26#v=onepage&amp;q=&amp;f=false and also in &quot;The Nature of Space and Time&quot; (online text) http://arxiv.org/abs/hep-th/9409195<br>Unsourced variants: Not only does God play dice with the Universe; he sometimes casts them where they can&#x27;t be seen.<br>Not only does God play dice, but... he sometimes throws them where they cannot be seen. <br class="br">Variant: So Einstein was wrong when he said &quot;God does not play dice&quot;. Consideration of black holes suggests, not only that God does play dice, but that He sometimes confuses us by throwing them where they can&#x27;t be seen.

"Colonies in space may be only hope, says Hawking" by Roger Highfield in Daily Telegraph (16 October 2001).

As quoted in &quot;Stephen Hawking: &#x27;There is no heaven; it&#x27;s a fairy story&#x27;&quot; by Ian Sample, in The Guardian (15 May 2011) http://www.theguardian.com/science/2011/may/15/stephen-hawking-interview-there-is-no-heaven <br class="br">Context: I have lived with the prospect of an early death for the last 49 years. I&#x27;m not afraid of death, but I&#x27;m in no hurry to die. I have so much I want to do first... I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.

As quoted in Stephen Hawking&#x27;s Universe http://books.google.com/books?id=lkntNIwunAAC&amp;pg=PA77&amp;dq=hawking+%22my+goal+is+simple%22&amp;ei=q5HtSvCOIoLklQTU_cWhDA#v=onepage&amp;q=hawking%20%22my%20goal%20is%20simple%22&amp;f=false (1985) by John Boslough, Ch. 7 : The Final Question, p. 77

Source: Black Holes and Baby Universes and Other Essays (1993), pp. 133–135.
Context: The ultimate objective test of free will would seem to be: Can one predict the behavior of the organism? If one can, then it clearly doesn't have free will but is predetermined. On the other hand, if one cannot predict the behavior, one could take that as an operational definition that the organism has free will … The real reason why we cannot predict human behavior is that it is just too difficult. We already know the basic physical laws that govern the activity of the brain, and they are comparatively simple. But it is just too hard to solve the equations when there are more than a few particles involved … So although we know the fundamental equations that govern the brain, we are quite unable to use them to predict human behavior. This situation arises in science whenever we deal with the macroscopic system, because the number of particles is always too large for there to be any chance of solving the fundamental equations. What we do instead is use effective theories. These are approximations in which the very large number of particles are replaced by a few quantities. An example is fluid mechanics … I want to suggest that the concept of free will and moral responsibility for our actions are really an effective theory in the sense of fluid mechanics. It may be that everything we do is determined by some grand unified theory. If that theory has determined that we shall die by hanging, then we shall not drown. But you would have to be awfully sure that you were destined for the gallows to put to sea in a small boat during a storm. I have noticed that even people who claim everything is predetermined and that we can do nothing to change it, look before they cross the road. … One cannot base one's conduct on the idea that everything is determined, because one does not know what has been determined. Instead, one has to adopt the effective theory that one has free will and that one is responsible for one's actions. This theory is not very good at predicting human behavior, but we adopt it because there is no chance of solving the equations arising from the fundamental laws. There is also a Darwinian reason that we believe in free will: A society in which the individual feels responsible for his or her actions is more likely to work together and survive to spread its values.

The Universe in a Nutshell (2001), p. 59
Context: One might think this means that imaginary numbers are just a mathematical game having nothing to do with the real world. From the viewpoint of positivist philosophy, however, one cannot determine what is real. All one can do is find which mathematical models describe the universe we live in. It turns out that a mathematical model involving imaginary time predicts not only effects we have already observed but also effects we have not been able to measure yet nevertheless believe in for other reasons. So what is real and what is imaginary? Is the distinction just in our minds?

British Telecom advertisement (1993), part of which was used in Pink Floyd's Keep Talking (1994) and Talkin' Hawkin'<nowiki/> (2014)
Context: For millions of years, mankind lived just like the animals. Then something happened which unleashed the power of our imagination. We learned to talk and we learned to listen. Speech has allowed the communication of ideas, enabling human beings to work together to build the impossible. Mankind's greatest achievements have come about by talking, and its greatest failures by not talking. It doesn't have to be like this. Our greatest hopes could become reality in the future. With the technology at our disposal, the possibilities are unbounded. All we need to do is make sure we keep talking.

Source: A Brief History of Time (1988), Ch. 12
Context: Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe? The usual approach of science of constructing a mathematical model cannot answer the questions of why there should be a universe for the model to describe. Why does the universe go to all the bother of existing?

Response upon being questioned as to his IQ, in interview with Deborah Solomon "The Science of Second-Guessing", The New York Times (12 December 2004)

Speech at Macworld Expo in Boston, as quoted in The Daily News (4 August 1994) http://news.google.com/newspapers?id=bD8PAAAAIBAJ&amp;sjid=IoYDAAAAIBAJ&amp;pg=4837%2C5338590. A nearly identical quote can be found at the end of the second paragraph of his lecture Life in the Universe http://hawking.org.uk/index.php?option=com_content&amp;view=article&amp;id=65 (1996).