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Re: a relativity question

In a message dated 11/26/2002 11:48:18 AM Eastern Standard Time, ajm@CSUPOMONA.EDU writes:

Does not a photon change mass/energy/wavelength/color as it climbs the
gravitational potential hill of the earth?

The mass doesn't change; it is always zero. The energy changes in a
way that depends on the choice of reference frame just like
that of a
ball or any other object.

This reminds me of an article I saw in the New York Times science section from last week. The article was about methods of averting a collision with an asteroid. One of the sidebars referred to infrared photons, which "have a slight mass." It did not elaborate.

Justin

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.