Commemorative Envelopes created with
US Postal Service Cancellation
to Honour Feynman
Here is the art for the front of the commemorative envelope available for
cancellation with the special "Feynman Cancellation".
The back has the explanation of the diagram used in the cancel. The text
The Feynman Diagram used for the postal cancel on this envelope depicts what is known
as a "bubble process." It shows a high energy particle, for example, a cosmic
ray from a distant supernova, which emits a high energy photon of light, for example, a
gamma ray. The photon, in turn, creates a particle and an anti-particle that exist for a
brief moment and then recombine. As Feynman liked to point out, an anti-particle is the
same thing as a particle with negative energy traveling backward in time (which is why the
arrow at d points backwards, i.e. to the left). So you could say the photon created only
one particle that, at first, traveled forward in time (the bottom semicircle) and then
reversed and went back in time (the top semicircle) and annihilated itself! By inventing
diagrams like this, Richard Feynman made it much easier to understand what is going on in
the interactions between sub-atomic particles without getting lost in tremendous amounts
of tedious math.
Here is the art for the back.
Information on these envelopes and the club is available from TTCS, 513-6th Ave. S.,
Lake Worth FL 33460-4507. Or E-mail: email@example.com.
Added May 2.