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for discussion,here are some abstract and an email from L.Smolin.

A recent conclusive paper as well https://arxiv.org/abs/2201.06988Many thanks for writing. FIrst, let me say that I am a huge fan of Tom B, and read and think about many of his papers. My own impression is that he greatly weakens the power and influence of his thought by hiding his pretty radical ideas in the

language of adS/CFT tc, which is incapable of fully expressing them. Same thing for Willy F. At least the importance of Ted Jacobson's work has gotten through to them.

As for their Holographic Spacetime, I like the idea, but my understanding is it is essentialy the model of quantum spacetime that Fotini Mrkopoulou proposed some years earlier under the name of quantum causal histories. In my opinion that was too bad because thy could make good use of the further work by her on coarse graining and RG based on Cremmer-Cohen's ideas and Heyting algebras.

**The formalism of Holographic Space-time (HST) is a translation of the principles of Lorentzian geometry into the language of quantum information. Intervals along time-like trajectories, and their associated causal diamonds, completely characterize a Lorentzian geometry. The Bekenstein-Hawking-Gibbons-'t Hooft-Jacobson-Fischler-Susskind-Bousso Covariant Entropy Principle, equates the logarithm of the dimension of the Hilbert space associated with a diamond to one quarter of the area of the diamond's holographic screen, measured in Planck units. The most convincing argument for this principle is Jacobson's derivation of Einstein's equations as the hydrodynamic expression of this entropy law. In that context, the null energy condition (NEC) is seen to be the analog of the local law of entropy increase.**I'd like to know what the community's ideas are on the basic principles and viability of HST,and also as Smolin has pointed out,the implications of Jacobson's work and the correlations with HST.