... constant¹

It is worth pointing out that there has been some non-trivial criticism of this construction. Put crudely, the construction is entirely at the level of effective field theory, and it is unclear that it really can be embedded into a full `stringy' setup. Since this is a technical point beyond the scope of this review, I will have nothing more to say about it here.

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... Principle²

To quote Lenny Susskind: `We live where we can live.', (New York Times, Sept. 2, 2003)

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