The Grand Design

The most incomprehensible thing about the universe is that it is comprehensible.

 -Albert Einstein 

A unifying theory of the universe is the holy grail of modern physics. Einstein sought but did not find it. The great Cambridge mathematician Stephen Hawking and CalTech physicist Leonard Mlodinow believe they have found that unifying theory in something called M-theory. They take us on a journey I can only sketch in their elegant book The Grand Design (Bantam 2010).

Why is there something rather than nothing?

Why do we exist?

Why this particular set of laws and not some other? 

This is the ultimate question of life, the universe, and everything.

Humans have tried to explain the universe since the dawn of our consciousness. Kepler, Galileo, Descartes, and Newton thought the laws that govern the universe came from God. Contemporary classical science posits "a real external world whose properties are definite and independent of observers." A newer approach that Hawking and Mlodinow endorse is called model-dependent realism. It says that if two models both agree with scientific observation, we cannot say which is more or less real. 

Since 1999, a series of experiments in which physicists fire molecules toward a barrier with two slits in it have led to the conclusion in quantum physics that these molecules have alternative histories of how they travel through the two slits.

There is no single reality of their journey. Measuring them as they travel changes their journey. The great eccentric physicist Richard Feynman said, "I think I can safely say that nobody understands quantum mechanics." Feynman's quantum observations are fundamental, in ways I cannot detail here, to M-theory as a unifying theory. Essentially, it turns out that the only way to try (so far with only partial success) to unify the four forces of nature is to use quantum theories.

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