Mansoor’s Reviews > Conversations on Quantum Gravity > Status Update

According to the principles of Einstein’s theory, you can’t unambiguously form a superposition of the two spacetimes, unless you have a map that relates one into the other in a certain way. While this is possible to do if both spacetimes are flat, there is no determined way to map two curved spacetimes, which is problematic. To solve this problem I am not asking for a theory of quantum gravity.
—Sir Roger Penrose

There are lots of people who are running around with different ideas and many of those ideas are wrong. People often don’t care too much about that. If you have a wrong idea you can still make a living
out of it.
—Gerard ’t Hooft

The universe started at some point; that is, it started with some initial state. If we believe that quantum mechanics describes that initial state then that initial state is fuzzy. But how can the beginning of the universe be fuzzy? People like Stephen Hawking have their answers but I think their answers are a bit mystical and I have difficulties with those answers.
—Gerard ’t Hooft

String theory has very loose foundations; it is like an enormous impressive castle built on mud and so the castle is beautiful but the foundations are awful.
—Gerard ’t Hooft

I remember an instance where I was in a conference in California and I wanted to ask a group of string theorists why they begin by looking at the S-matrix, since that already presupposes many things. At that time I was told that this discussion should not be taken (laughs). I find this absolutely ridiculous.

—Alain Connes

In a world that is becoming increasingly more crazy, I think that the most important thing we have to offer to the world is an unwavering belief in the idea of truth. The power of the belief in the truth, without blinding yourself, is something that has guided us for 2000
years and is the bedrock of western society for the past 400 years. However, I am worried that we are currently losing track of it.
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There are two philosophies for how to do physics: there’s conservative radicalism and radical conservatism. The former is bad and the latter is good. Conservative radicalism is the philosophy that we should be radical and relax assumptions of established physics. For instance, you can say that the speed of light isn’t constant or that there is no Lorentz invariance.
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