- #1

nomadreid

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## Summary:

- When one conjectures about emergent spacetime, one usually refers to either the holographic theory (which only reduces the dimensions), or networks of entanglement, or networks of tensors, or strings, or some combination. But it seems that, for all these, there is an underlying basis of quantum states, but quantum states are defined in terms of spacetime. Isn't this circular?

## Main Question or Discussion Point

Googling "emergent spacetime" I get lots of articles which offer various conjectures about what that may be; an overview for example is given in http://guava.physics.uiuc.edu/~nigel/courses/569/Essays_Spring2018/Files/gupta.pdf. However, although I understand that emergent spacetime is not yet a solid theory, don't all these conjectures ultimately rest upon information coded in quantum states? But the variables of quantum states include those of space and time, no? I am not qualified to go deeply into all of these theories to unravel the seeming circularity of defining spacetime in terms of spacetime, but perhaps someone could give me a rough outline as to why this is not circular?

While I am at it (might as well get hung for a sheep as for a lamb): using the holographic theory, one ends up with information encoded on the boundary. Can one say that this is generating spacetime, or just reducing the dimensions used in our description of spacetime?

While I am at it (might as well get hung for a sheep as for a lamb): using the holographic theory, one ends up with information encoded on the boundary. Can one say that this is generating spacetime, or just reducing the dimensions used in our description of spacetime?