Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe

by Brian Greene

Even if the region appears empty, seemingly containing no energy at all, quantum theory shows that its energy content actually rapidly fluctuates up and down, yielding zero energy only on average. These are the same type of quantum fluctuations that gave rise to the temperature variations in the cosmic microwave background radiation that we encountered in chapter 3. Through E = mc2, such quantum energy fluctuations can also show up as quantum mass fluctuations—particles and their antiparticle partners popping into existence in otherwise empty space. This is happening right now in front of your eyes, yet however intently you stare you’ll see no evidence of it. The reason is that quantum mechanics also dictates that such particle-antiparticle pairs quickly find each other, annihilate and fade back into empty space. We do detect indirect signatures of these ephemeral machinations because it is only when we include them in our calculations that we achieve the stunning agreement between predictions and measurements that has justifiably made quantum mechanics the centerpiece of fundamental physics.7 Hawking revisited these quantum processes but now imagined them taking place just outside the event horizon of a black hole. When a particle-antiparticle pair pops into this environment, sometimes the two particles will annihilate quickly, just as they would anywhere else. But, and this is the point, Hawking realized that on occasion they will not annihilate. Sometimes one member of ...