Let me know if my attempted synopsis above is helpful or not... I think I can confidently say that the crystal does not travel backwards in time (or forwards in time any faster than the normal rate, as has been pointed out).
However, it is a seemingly miraculous trick of spin systems that we are able to use pulses to effectively reverse the time evolution of the system and produce echoes. When looking at one new pulse sequence which had many pulses, the discoverer of the spin echo (Erwin Hahn) said "With that many pulses I could bring back the Messiah!" [1].
However, it is a seemingly miraculous trick of spin systems that we are able to use pulses to effectively reverse the time evolution of the system and produce echoes. When looking at one new pulse sequence which had many pulses, the discoverer of the spin echo (Erwin Hahn) said "With that many pulses I could bring back the Messiah!" [1].
[1, PDF] https://pines.berkeley.edu/sites/default/files/publications/...