photon• Consider a photon which is polarisedparallel to the opticalaxis of P, .• But photons are extremely oddparticles indeed.• How will you capturephotonsfast enough to propel the sail at speed and over long distances?• The great advantage of using lower-energy photons rather than X-rays is the greater resolution attainable.• But here things are very different: each individualphotonbehaves like a wave entirely on its own!• Consider also, this kind of phenomenonaffects not just photons, but every particle in every interaction.• How can it be that by allowing the photon an alternativeroute, we have actually stopped it from traversing either route?• The two photons are like the left and the right eyes of the cat.