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

by Brian Greene

A more convincing approach is to challenge the underlying scenario itself: Central to the argument for Boltzmann brains is the existence of a distant cosmological horizon continuously radiating particles, the raw materials for building complex structures, including minds. Over the long haul, if the dark energy filling space were to dissipate away, then accelerated expansion would draw to a close and the cosmological horizon would withdraw. Without a distant surrounding surface radiating particles, the temperature of space would close in on zero, and with that the chance of spontaneously forming complex macroscopic structures would close in on zero too. There is as yet no evidence for a weakening (or a strengthening) of dark energy, but future observational missions will study the possibility with greater precision. A conservative assessment is that the jury is still out.