|Standard theory of particle physics|
We have now two great physical theories:
· On one side, quantum mechanics, which applies primarily to very small objects (those scarcely affected by gravity), and is the basic tool for the standard theory of particle physics.
· On the other, general relativity, which applies to very large objects (from the planets to the whole universe, those for which almost nothing matters except gravity), and is the main tool for the standard cosmological (Big Bang) theory.
Unfortunately, the two theories are not mutually compatible, so that physics is far from having resolved its outstanding issues. Moreover, these two theories depend on about forty independent variables. Many physicists think that they are too many. If it were true, it would mean that the configuration space of nature has about forty dimensions. If it is difficult to imagine a four-dimensional space, what about forty!