[Sabertooth]

Caused? That seems to me an inappropriate extrapolation.

Why do you think so?

[edsheppa]

Many reasons. Our intuitive notions of causation are unreliable as can be seen by discoveries of the last century. Even had they not, it isn't appropriate to extrapolate from everything in the universe having a cause to the universe (and this is what you mean by nature, no?) having a cause. Isn't it even a category error since causation is law-like correlation in time and, supposing the universe to include time itself, cannot apply to time itself.