  The physicists of the early 20th century were unaware of two ideas which are
vital to understanding some aspects of modern physics within classical theory.
The two ideas are: 1) the presence of classical electromagnetic zero-point
radiation, and 2) the importance of special relativity. In classes of modern
physics today, the problem of blackbody radiation within classical physics is
still described in the historical context of the early 20th century. However,
the inclusion of classical zero-point radiation and of relativity now allows a
completely satisfactory classical understanding of blackbody radiation with the
Planck spectrum, as well as of some other aspects of modern physics. Here we
sketch the current classical understanding of blackbody radiation, pointing out
that thermodynamics allows the presence of classical zero-point radiation, and
that use of nonrelativistic physics leads to the Rayleigh-Jeans spectrum while
relativistic physics gives the Planck spectrum. The current textbooks of modern
physics are a century out of date in presenting the connections between
classical and quantum physics.
