**Physicist Andrei Linde wants to know: Since we live in this weird universe - fractal, self-replicating, inflationary - does that imply that it was created not by God, but by some physicist-hacker?**

**Andrei Linde, a 47-year-old physicist from Moscow, started teaching at Stanford University in 1990. He lives there with his wife, Renata Kallosh (also a Stanford physics professor, specializing in superstrings and supergravity), and his two sons, Dmitri and Alex. In 1982, he began formulating a new theory of the universe - an improvement on the big-bang model. He uses computer simulations for much of his research, and he has recently suggested that our universe may be the result of a physicist-hacker's experiment. An attractive, tidily dressed man, Linde speaks with a thick Russian accent and a colorfully inverted syntax. His responses to the questions of mathematician Rudy Rucker have been smoothed by Rucker's interpolation and editing.**

Two scalar fields that are important for inflationary theories are sometimes called the inflaton field and the Higgs field. These fields fill the universe and show their presence by affecting the properties of elementary particles. You don't notice a constant scalar field any more than you notice a constant air pressure or a constant electric charge. When there is a large air pressure, you get wind; when there is a large electrical charge, you get sparks; and when there is a large scalar field called the inflaton field, you get an expansion of space. Quantum mechanics implies that the scalar fields undergo unpredictable fluctuations as a result of the uncertainty principle. If there is a place where the fluctuations make the inflaton field sufficiently large, then at this spot the universe begins expanding very rapidly, which creates so much space that we can safely live there.

*Wired*:What about the "self-reproducing" aspect of your model?

Linde:The fluctuations that increase the speed of inflation can happen over and over, again because of the essential fuzziness that the uncertainty principle of quantum mechanics introduces into the equation. This makes the universe self-reproducing; the universe actually replicates itself in all its forms.

The standard big-bang theory depicts a homogeneous universe that looks like a single bubble. But if we take into account quantum effects, the self-reproducing inflationary universe is a bubble producing new bubbles producing new bubbles producing new bubbles and so on. This kind of repeatedly branching pattern is what mathematicians call a fractal. A fractal pattern is characterized by the property that the small bits of the pattern are exact replicas of the whole pattern. An oak tree, for example, is like a fractal in that a single branch of an oak resembles a scaled-down model of the entire tree. Another example of a fractal is a mountain range. If you chop off the top of a mountain and look at it closely, it resembles the whole mountain range; a single rock on the mountain resembles a whole mountain in itself.

So, we think of the self-reproducing inflationary universe as a fractal. The big bang works as a description of each particular bubble, but it cannot describe the growing fractal. In the fractal model, there is no real reason for the universe to stop growing - indeed, it is likely to keep growing and blooming in new regions forever.