''History Of Time''

This is an attempt to illustrate some current theoretical thinking

that indicates that time may not have any beginning or end.

Not bad, not bad at all. The history of time can be regarded (as well) as the history of the four fundamental forces/the four fundamental interactions or forces. The large circle in the middle represents all four forces unified in the time scale since beginning - 0, when the temperature was (close to) infinite. When the temperature dropped (time scale since beginning 10-11 s) these forces separated from each other, the four smaller circles. After that event the present history of TIME had begun. This history may not be the only one, or most probbaly is only a moment of the infinity. Nice work! Cheers!