Shut up and calculate
Max Tegmark
Dept. of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
I advocate an extreme “shut-up-and-calculate” approach to physics, where our external physical reality is assumed to be purely mathematical. This brief essay motivates this “it’s all just equations” assumption and discusses its implications.
What is the meaning of life, the universe and everything? In the sci-fi spoof The Hitchhiker’s Guide to the Galaxy, the answer was found to be 42; the hardest part turned out to be finding the real question. Indeed, although our inquisitive ancestors undoubtedly asked such big questions, their search for a “theory of everything” evolved as their knowledge grew. As the ancient Greeks
replaced myth-based explanations with mechanistic models of the solar system, their emphasis shifted from asking “why” to asking “how”.
Since then, the scope of our questioning has dwindled in some areas and mushroomed in others. Some questions were abandoned as naive or misguided, such as explaining the sizes of planetary orbits from first principles,
which was popular during the Renaissance. The same may happen to currently trendy pursuits like predicting the amount of dark energy in the cosmos, if it turns out that the amount in our neighbourhood is a historical accident. Yet our ability to answer other questions has surpassed earlier generations’ wildest expectations: Newton would have been amazed to know that we would one day measure the age of our universe to an accuracy of 1 per cent, and comprehend the microworld well enough to make an iPhone.
Mathematics has played a striking role in these successes. The idea that our universe is in some sense mathematical goes back at least to the Pythagoreans of ancient Greece, and has spawned centuries of discussion among physicists and philosophers. In the 17th century, Galileo famously stated that the universe is a “grand book” written in the language of mathematics. More recently, the physics Nobel laureate Eugene Wigner argued in the 1960s that “the unreasonable effectiveness of mathematics in the natural sciences” demanded an explanation.
Here, I will push this idea to its extreme and argue that our universe is not just described by mathematics — it is mathematics. While this hypothesis might sound rather abstract and far-fetched, it makes startling predictions about the structure of the universe that could be testable by observations. It should also be useful in narrowing down what an ultimate theory of everything can look like.
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