Year: 2022

ONLY DEFINED BY RELATION. “So much the worse, it seems, for the relationist tradition, stemming from Leibniz through Berkeley and Mach, of denying that space, time (and space-time), and their parts, are objects; and of conceiving them instead as a system of spatiotemporal relations between bodies. For the bodies have become diaphanous and omnipresent fields, which are themselves complicated structures of properties and relations among spacetime points.” https://lnkd.in/dMm_YkR View in LinkedIn

OTHER ISSUES. “But there are many interpretative issues about quantum theory, such as entanglement and non-locality, which we need not engage here.” https://lnkd.in/dMm_YkR View in LinkedIn

THE FOOTNOTE. “Decoherence is an important aspect of quantum theory’s ‘recovery’ of a classical realm.” https://lnkd.in/dMm_YkR View in LinkedIn

EIGENSTATES. “Decoherence is a process that rapidly puts macroscopic objects (including tiny ones such as dust particles) that interact with their environment (even very slightly, such as with the microwave background radiation) into mixtures, whose components are, in typical cases, approximate position eigenstates. The process diffuses the interference terms characteristic of the macro-object’s initial superposition into the environment, so that its statistical behaviour is as if it is in a mixture—and a mixture of states that have definite values for familiar quantities like position, or quantities very ‘close’ to those like position.” https://lnkd.in/dMm_YkR View in LinkedIn

THE STRETCH. “Our washing up is just like our language. We have dirty water and dirty dishcloths, And yet we manage to get the plates and the glasses clean. In language too, we have to work with unclear concepts and form a logic whose scope is restricted in an unknown way, and yet we use it to bring some clarity into our understanding of nature.” (Neils Bohr, page 4) https://lnkd.in/d_2R77E View in LinkedIn

The cathedral in Barcelona, a grand old lady. View in LinkedIn

THE OBSERVER REQUIREMENT. “The endeavour of quantum gravity is closely related to quantum cosmology, i.e., the attempt to have a quantum theory of the whole universe. And in quantum cosmology, the traditional Copenhagen interpretation, with its requirement of an observer external to the system, is obviously inapplicable.” https://lnkd.in/dMm_YkR View in LinkedIn

OTHERNESS. “The Copenhagen interpretation is one that requires, not an observer, but a ‘classical background’ external to the system. And, arguably, one obvious candidate for such a background is the continuous spacetime manifold of our usual quantum theories (both quantum mechanics and quantum field theories). But we admit to giving this sort of interpretation little credence.” https://lnkd.in/dMm_YkR View in LinkedIn

THE PROBLEM OF TIME. “The canonical quantisation of general relativity leads to a quantum state-vector which is a functional of 3-geometries; (this subject is known as ‘quantum geometrodynamics’). But there are immense mathematical and conceptual difficulties about this quantisation. Prominent among the conceptual difficulties is what is what is perhaps the best-known philosophical topic arising from quantum gravity: the so-called ‘problem of time’.” https://lnkd.in/dMm_YkR View in LinkedIn

TANGLED KNOT. “What then is the problem of time? As emphasized by Kuchar it is really a cluster of problems that arise principally from the disparate ways in which time is treated in quantum theory and in general relativity.” https://lnkd.in/dMm_YkR View in LinkedIn