hansen, <hansen@best.com>, quotes David Deutsch:
> "To those who still cling to a single-universe world-view, I
> issue this challenge: explain how Shor's Algorithm works. ....
> When Shor's Algorithm has factorized a number, using 10^500 or
> so times the computational resources that 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
> miniscule 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. ..." p 217
I don't agree with Deutsch's suggestion that quantum computers would imply
that the Many-Worlds interpretation must be true. He is not correct
to say that running Shor's algorithm has used many times the computing
resources that can be seen to be present. The quantum computer is
clearly seen to be present; it is put into a superposition of states and
run through a series of transforms, and at the end the answer comes out.
The quantum computer is more powerful than an ordinary computer, and
requires correspondingly more care in its preparation and use, but it
does not use invisible resources.
The reason for the computational power is that the machine is put into
a superposition of states. But such superpositions are observed every
day in quantum experiments, like double slit diffraction.
Hal