It's a reference to the Doppler effect. As an observer is moving towards a light source its spectrum appears to the observer to be shifted into the blue region. Hence "blue shift."
If you are moving away from the source then it is shifted into the red. Of course this assumes that you are speaking about the visible light spectrum.
Slashdot Mirror
It's a reference to the Doppler effect. As an observer is moving towards a light source its spectrum appears to the observer to be shifted into the blue region. Hence "blue shift."
If you are moving away from the source then it is shifted into the red. Of course this assumes that you are speaking about the visible light spectrum.