A question about the doppler shift for light?

EDITED RESPONSE!

Actually, most metal will block gamma rays if it is thick enough, But that is not relevant to your question which is a very insightful and reasonable question about relativity, unlike most questions on this subject that appear in Yahoo! Answers.

The fact is that this is not entirely a relativity question. Energy value is not independent of the observer. The earth observer can calculate the frequency of the light as observed by the traveler by using the relativistic doppler formula fo = fe(1 + v/c)/√[1 - (v/c)^2], The traveling observer will see the shortened wavelength because of relativistic doppler shift.

Energy is not observer independent, and that goes for photon energy as well as kinetic energy. If you were to determine the energy of a moving object with respect to another moving object, you would calculate the first object's velocity from from the point of view of the second, not your own. So would you compute the wavelength of the arriving photons: with respect to the traveler, not your perspective.

There are formulas published for both relativistic velocity summation and doppler shift; I suspect that the resulting apparent wavelength will come out the same for both observers.

In any case, unlike in quantum mechanics, both observers must agree as to whether the traveler is poisoned.

You've answered your own question, but for the lay person I suspect the basic response would be something along the line of "Holy Crap! He was going fast!" But you might need a window in the front of the spaceship. It might not look like one to you, but you're dead, so you don't count.

You answered your own question. What they saw (heard, felt, tasted, smelled) was it **their** reference frame. Not yours.

Doug