Time and Spacetime: The Crystallizing Block Universe

Understand

The nature of the future is completely different from the nature of the past.

• When quantum effects are significant, the future shows all the signs of quantum weirdness, including duality, uncertainty, and entanglement.
• With the passage of time, after the time-irreversible process of state-vector reduction has taken place, the past emerges, with the previous quantum uncertainty replaced by the classical certainty of definite particle identities and states.
• The present time is where this transition largely takes place, but the process does not take place uniformly: Evidence from delayed choice and related experiments shows that isolated patches of quantum indeterminacy remain, and that their transition from probability to certainty only takes place later.