# Quote — Stephen W. Hawking, A Brief History of Time

> 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?

- Author: [Stephen W. Hawking](https://www.leafyquotes.com/stephen-w-hawking.md)
- Book: [A Brief History of Time](https://www.leafyquotes.com/stephen-w-hawking/a-brief-history-of-time.md)
- Page: 174
- Source: [Wikiquote](https://en.wikiquote.org/wiki/Stephen_Hawking#A_Brief_History_of_Time_(1988)) ([CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/))
- Quote page: https://www.leafyquotes.com/stephen-w-hawking/a-brief-history-of-time/even-if-there

## More from this book

> Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory. As philosopher of science Karl Popper has emphasized, a good theory is characterized by the fact that it makes a number of predictions that could in principle be disproved or falsified by observation. Each time new experiments are observed to agree with the predictions the theory survives, and our confidence in it is increased; but if ever a new observation is found to disagree, we have to abandon or modify the theory.

p. 10 — [Quote page](https://www.leafyquotes.com/stephen-w-hawking/a-brief-history-of-time/any-physical-theory.md)

> One could say: "The boundary condition of the universe is that it has no boundary." The universe would be completely self-contained and not affected by anything outside itself. It would neither be created nor destroyed. It would just BE.

p. 136 — [Quote page](https://www.leafyquotes.com/stephen-w-hawking/a-brief-history-of-time/one-could-say.md)

> The laws of science, as we know them at present, contain many fundamental numbers, like the size of the electric charge of the electron and the ratio of the masses of the proton and the electron. ... The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life.

p. 125 — [Quote page](https://www.leafyquotes.com/stephen-w-hawking/a-brief-history-of-time/the-laws-of-science.md)