EINSTEIN'S UNFINISHED REVOLUTION

The latest update on physicists’ painful efforts to make sense of quantum mechanics.

So far they’ve failed, but Smolin (Time Reborn: From the Crisis in Physics to the Future of the Universe, 2013, etc.), a founding faculty member of the Perimeter Institute for Theoretical Physics, believes they’re on the right track, and readers who pay close attention may understand what he is attempting to explain. Einstein’s theory of relativity delivered an accurate explanation of space, time, and matter for most of the universe, but it breaks down at the level of atoms: the quantum world. Quantum mechanics works beautifully but only by postulating paradoxes and nonsensical behavior such as an electron being both a particle and a wave depending on the experiment. Einstein insisted that this didn’t make sense, but most colleagues had no objection. Smolin reminds readers that this is an argument between realists and nonrealists. Realists ask, “does the natural world exist independently of our minds?” and “can we understand enough about the laws of nature to explain the history of our universe and predict its future?” Current quantum theory says no. Nobel Prize winner Louis de Broglie proposed a “realistic” explanation in his 1927 pilot wave theory. Unlike the already dominant anti-realist view of Bohr and Heisenberg, his electron remains a particle, and an electron-wave flows through space, directing the particle where to go. The concept of pilot waves did not catch on, but after 1950, some mainstream physicists began looking seriously into realistic theories through concepts such as hidden variables, the many-worlds view, and nonlocality. None of these men are household names, and their studies poke a few holes in traditional theory without simplifying matters. Since quantum mechanics continues to work well, most physicists pay little attention.

This is a philosophical debate that has disturbed thoughtful scientists for a century. Its ideas are fundamental, but the details are complex. Smolin works hard and with mixed success to explain these to a lay readership.