Task: Text Categorization
Input (English): The cooling named for this effect is a type of laser cooling that impacts particles within a certain   range of speeds. A profile named for this effect is used to find the temperature of a gas based on the  way that this effect broadens spectral lines. The transverse type of this effect is explained by the   time dilation of special relativity and was confirmed by the Ives-Stilwell experiment. Astronomical  measures of this effect led to the development of Hubble's Law and the belief that the universe  is expanding. Name this change of frequencies such as redshifts and blueshifts caused by relative  velocities between a source and observer.
Output (English): Science