“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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Stephen Hawking 122
British theoretical physicist, cosmologist, and author 1942–2018Related quotes
Source: https://www.lifewithoutacentre.com/writings/shockingly-simple-principles-of-spiritual-awakening/

As he said in the Greek parliament
Source: https://www.youtube.com/watch?v=wqZeImBRWjc
“What’s real is what’s valuable. Everything else is just an illusion.”
Source: Lady of Mazes (2005), Chapter 17 (p. 183).