TY - JOUR PB - American Physical Society ID - 10.1103/PhysRevFocus.6.22 TI - Why Now? JF - Physical Review Focus JA - Phys. Rev. Focus J1 - FOCUS VL - 6 IS - SP - 22 EP - PY - 2000/11/16/ UR - http://link.aps.org/doi/10.1103/PhysRevFocus.6.22 A1 - Matthews, Robert ER -