Ultimate Models for the Universe

The history of physics has seen the development of a sequence of progressively more accurate models for the universe—from classical mechanics, through quantum mechanics, to quantum field theory, and beyond. And one may wonder whether this process will go on forever, or whether at some point it will come to an end, and one will reach a final ultimate model for the universe.

Experience with actual results in physics would probably not make one think so. For it has seemed that whenever one tries to get to another level of accuracy, one encounters more complex phenomena. And at least with traditional scientific intuition, this fact suggests that models of progressively greater complexity will be needed.

But one of the crucial points discovered in this book is that more complex phenomena do not always require more complex models. And indeed I have shown that even models based on remarkably simple programs can produce behavior that is in a sense arbitrarily complex.

So could this be what happens in the universe? And could it even be that underneath all the complex phenomena we see in physics there lies some simple program which, if run for long enough, would reproduce our universe in every detail?

The discovery of such a program would certainly be an exciting event—as well as a dramatic endorsement for the new kind of science that I have developed in this book.

For among other things, with such a program one would finally have a model of nature that was not in any sense an approximation or idealization. Instead, it would be a complete and precise representation of the actual operation of the universe—but all reduced to readily stated rules.

In a sense, the existence of such a program would be the ultimate validation of the idea that human thought can comprehend the construction of the universe. But just knowing the underlying program does not mean that one can immediately deduce every aspect of how the universe will behave. For as we have seen many times in this book, there is often a great distance between underlying rules and overall