Re: how can a particle have a spin of 1/2

Dear James,

How about a spin-2 particle like the postulated graviton that looks
the same when you have only gone half way around (180 degrees)?  Or a
spin-3/2 particle that looks the same when you rotate it by 240
degrees, 480 degrees, or 720 degrees, but NOT 360 degrees?  The
quantum world is quite odd; and models formed from our everyday
experience are not always helpful.  After a while, one simply accepts
the truth conveyed by the mathematics and stops trying to visualize.
Nobel Prize-winning physicist Richard P. Feynman warned to avoid
asking questions like "How can it be like that?" in quantum mechanics
because you'll find yourself "down the drain."

There is, however, experimental support for the conclusions reached 
mathematically.  See, for example, http://www.lbl.gov/abc/wallchart/chapters/05/1.html


--Randall J. Scalise    http://www.phys.psu.edu/~scalise/