(no subject)

[mlr]

To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor's algorithm works. I do not merely mean predict that it will work, which is merely a matter of solving a few uncontroversial equations. I mean provide an explanation. When Shor’s algorithm has factorized a number; using 10[500] or so times the computational resources than can be seen to be present, where was the number factorized? There are only about 10[80] atoms in the entire visible universe, an utterly minuscule number compared with 10[500]. So if the visible universe were the extent of physical reality, physical reality would not even remotely contain the resources required to factorize such a large number. Who did factorize it, then? How, and where, was the computation performed?

David Deutsch

from a New Yorker article about David Deutsch & quantum computing