"Am I right to assume by this that you mean 'at least four dimensions'?"
Technically speaking, perhaps. But if I understand the hyperspace model
correctly, six of the ten dimensions are "inaccessible"; that is, we cannot
perceive or interact with them directly, even though (as Dave explains) they
account for the non-gravitational interactions of the universe. As such,
for all intents and purposes, we can limit the universe to four dimensions.
However, as far as my question is concerned, it would not matter whether the
universe in fact had five, six or even more perceivable dimensions, just as
long as it had more than three.
Kevin L. O'Brien