Leonard Susskind (born 1940) is a very prominent physicist, being widely regarded as one of the fathers of “string theory.” He is currently the Felix Bloch Professor of Theoretical Physics at Stanford University, and is also the author of Cosmic Landscape: String theory and the illusion of intelligent design.

These comments are from an interview with him by Amanda Gefter. It was published in issue 2530 of New Scientist magazine, 17 December 2005, page 48, entitled, “Is String Theory in Trouble?”.

The introduction to the article states that, according to string theory, there could be, not one universe, but “10⁵⁰⁰, each with different constants of nature, even different laws of physics.” It goes on:

The inventor of string theory, physicist Leonard Susskind, sees this “landscape” of universes as a solution rather than a problem. He says it could answer the most perplexing question in physics: why the value of the cosmological constant, which describes the expansion rate of the universe, appears improbably fine-tuned for life. A little bigger or smaller and life could not exist. With an infinite number of universes, says Susskind, there is bound to be one with a cosmological constant like ours.

Within the article Mr. Susskind states, very candidly:

…The value of the cosmological constant – the energy of empty space which contributes to the expansion rate of the universe – seems absurdly improbable, and nothing in fundamental physics is able to explain why.

He goes on to say that even if there were a million universes, that is “not enough for anthropic explanations; the chances of one of the universes being suitable for life are still too small.” Only if there are 10⁵⁰⁰ possible universes could there be one like ours.

As he states elsewhere in the interview, “even most of the hard-core adherents to the uniqueness view [i.e., that there is only one universe] admit that it looks bad.” This is, again, because of the incredible fine-tuning of the physical laws of the universe.

His answer to the last question of this interview shows just how committed many secular physicists are to finding some reason for not believing the universe was created by God, i.e., to not believe that the it is the product of “intelligent design.” At least, you have to appreciate his honesty in this regard:

If we do not accept the landscape idea are we stuck with intelligent design?

I doubt that physicists will see it that way. If, for some unforeseen reason, the landscape turns out to be inconsistent – maybe for mathematical reasons, or because it disagrees with observation – I am pretty sure that physicists will go on searching for natural explanations of the world. But I have to say that if that happens, as things stand now we will be in a very awkward position. Without any explanation of nature’s fine-tunings we will be hard pressed to answer the ID critics. One might argue that the hope that a mathematically unique solution will emerge is as faith-based as ID.