Quotes from book
The Universe in a Nutshell

The Universe in a Nutshell

The Universe in a Nutshell is a 2001 book about theoretical physics by Stephen Hawking. It is generally considered a sequel and was created to update the public concerning developments since the multi-million-copy bestseller A Brief History of Time published in 1988.


Stephen Hawking photo
Stephen Hawking photo

“So what is real and what is imaginary? Is the distinction just in our minds?”

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?

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