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FRAGMENT FROM NATURE continues from last weekend and concludes this weekend on an exceptional article by Professor Jeremy Butterfield on quantum issues including gravity and time. We are lucky to have great minds contemplating these marvelous issues, for the world becomes a different place after their illuminations. View in LinkedIn

HOLOGRAM. “For a certain symmetry structure of the network, the gapless modes appear to inhabit a lower dimensional surface area, thereby displaying a holographic behaviour.” https://onlinelibrary.wiley.com/doi/full/10.1002/prop.201800007?casa_token=GdPRXs_tGLEAAAAA%3Ag-pxPMtkcleTYDUNK3mYGfpEzKRyc2LqQknTgFFB7dkYFDL8rDe2s0f4_0Q0oKjXD4_AEgFPGWolVTQ View in LinkedIn

This image is deeply embedded in ancient Girona stonework. 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

The cathedral in Barcelona, a grand old lady. 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

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 FOOTNOTE. “Decoherence is an important aspect of quantum theory’s ‘recovery’ of a classical realm.” 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

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