arXiv subjects

Alejandro Ascárate

Publications and source records attributed to Alejandro Ascárate.

4 recordsLinked to original sources

arXiv2021

Spacetime Relationalism in GR and QG

We provide here a philosophical basis for [arXiv:2012.03994, arXiv:2107.06693] based on the notion of spacetime relationalism. We argue that the view which is more cleanly compatible with GR is that in which the spacetime manifold is a relational (or 'emergent') property of the aggregate or physical sum of gravitational field portions, field that is considered material and for which spacetime geometry (in the sense of the metric properties) is one of its material properties. All of the previous philosophical notions are defined in relation to a clear ontology of material individuals, briefly described in the appendix. Furthermore, this fits well with the phase space of GR, thing that also may inform how to proceed in the quantum realm.

gr-qc↗

arXiv2021

The Ontology and Semantics of Quantum Theory for Quantum Gravity

Based on a clear ontology of material individuals, we analyze in detail the factual semantics of quantum theory, and argue that the basic mathematical formalism of quantum theory is just okay with (a certain form of ) realism and that it is perfectly applicable to quantum gravity. This is basically a process about 'cleansing' the formalism from semantic assumptions and physical referents that it doesn't really need (we use the term 'semantics' in the sense of the factual semantics of a physical theory, and not in the sense of model theory of abstract mathematics or logic). We base our study on the usual non-Boolean lattice of projectors in a Hilbert space and probability measures on it, to which we give a careful physical interpretation using the mentioned tools in order to avoid the usual problems posed by this task. At the end, we study a possible connection with the theory of quantum duration and time proposed in [arXiv:2012.03994, arXiv:2107.06693], for which this paper serves as a philosophical basis, and argue for our view that quantum gravity may show that what we perceive as change in the classical world was just (an ontologically fundamental) quantum collapse all along.

physics.hist-ph↗

arXiv2021

The Spacetime Picture in Quantum Gravity II

As a continuation to [12], we introduce a new formalism for (part of) QG, which we call TQG, since it's based on the NC Tori. This allows us to obtain numerous insights about the nature of time, like its discretization, its regular pace at the macroscopic scale, a solution to the Problem of Time, and a connection with the Measurement Problem and wave function collapse.

gr-qc↗

arXiv2021

The Spacetime Picture in Quantum Gravity

We propose an approach which, by combining insights from Loop Quantum Gravity (LQG), Topos theory, Non-commutative Geometry à la Connes, and spacetime relationalism, provides fertile ground for the search of an adequate spacetime picture in Quantum Gravity. With this approach, we obtain a novel way of deducing the quantization of the possible values for the area of a surface. One gets the same area values than those from the area operator in standard LQG, but our approach makes a further prediction: some smaller values and sub-divisions are also allowed. In addition, the area arises as a noncommutative distance between two noncommutative points, and thus they should be interpreted as irreducible string-like objects at the physical level (where the area interpretation for the noncommutative distance holds).

gr-qc↗