Complex sentence: Thus, testing the "new" metamaterial began for the effects described by Victor Veselago 30 years earlier, but only at first in the microwave frequency domain, and reversal of group velocity was explicitly announced in the related published paper.
Split into simpler sentences: Thus, testing the "new" metamaterial began for the effects described by Victor Veselago 30 years earlier, but only at first in the microwave frequency domain. Reversal of group velocity was explicitly announced in the related published paper.