There exist several computer programs which successfully model the discovery process in science. There are successful expert systems in medicine and other areas. But one area is a real challenge for such systems: theoretical physics. The most advanced knowledge discovery programs (like BACON written under the supervision of the Nobelist Herbert A. Simon) successfully reproduce only 17, 18, and 19 century physics, but stop short of explaining the very first formula of the 20 century: Planck's law of black body radiation. This law, discovered by an insight, led to the modern Quantum Physics. The programs stop short not because the computers are not fast enough: as Simon emphasized, we need new ideas -- not only new computers.
In the present paper, we present the natural symmetry ideas which lead directly to Planck's formula. Possible other applications of these ideas are discussed.