物理定律團 2 | 語意互相推卸責任論 3

Allowed topology changes (e.g. conifold transitions) may always be described as a condensation of objects on the original background; allowed (non-traversable) wormholes may be described as entangled states of objects (on a wormhole-free background) whose details reflect the properties of the wormhole.

So what is doomed isn’t a spacetime in the sense of our right of using the concept; what is doomed is the idea that a classical spacetime is unambiguously associated with states or processes. The association is not only refusing to be unique but to a large extent, the spacetime may be chosen arbitrarily (even its topology may be chosen differently, even if the topology change involves time in a nontrivial way). An inconvenient choice of the spacetime background for a given physical situation will be manifested in the complexity of the collections of particles and objects that live on top of the chosen spacetime but the theory will never say that the choice is “fundamentally wrong”.

So the advances in string/M-theory and quantum gravity have eliminated the idea that the reality canonically carries a “particular spacetime background”. At the fundamental level, the separation of the reality to the “spacetime” and “the objects that live on the spacetime” is highly redundant if not arbitrary. This fact may be viewed as a manifestation of the inevitable unification of gravity with other forces or matter. You just can’t objectively or canonically determine which part of the state or process or reality is gravity (space and time); and which part is the information about the objects or phenomena taking place on that background! Only some combination of theirs retains its unambiguous meaning.

— Is space and time emergent? ER-EPR correspondence adds a voice

— Lubos Motl

2013.10.31 Thursday ACHK