I do not know if you're being funny or not, because there is indeed a study of the minimum raw energy requirements for a given computation in our universe[1], so it is technically possible to rate the amount of computation something requires in terms of joules or your choice of energy unit. So I don't know if you know of this and are confused, or if you're trying to make a bad joke/pun on "power" (seems to be lolcraft's theory). Since there is a serious angle to your post, deliberate or otherwise, a serious answer:<p>Because encryption difficulties tend to scale exponentially as you add bits, it is relatively easy to make encryption that brute forcing would require more energy than exists in the known universe. As big as the Universe is, exponential is "bigger".<p>That's why even now the real problem is algorithms that have something far more clever than "brute force" available; we could already guarantee that even a post-Singularity adversary can't brute force our encryption (assuming they don't get new physics to play with), what we can't guarantee is that such an intelligence couldn't find a far more practical attack.<p>[1]: <a href="http://en.wikipedia.org/wiki/Limits_to_computation" rel="nofollow">http://en.wikipedia.org/wiki/Limits_to_computation</a>