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CONSENSUS DOUBTS. “Does such a universe conform to the holographic principle or the holographic bound? Susskind's argument based on collapse to a black hole is of no help here. Indeed, the holographic bound deduced from black holes must break down in a uniform expanding universe.” https://lnkd.in/draqjTW View in LinkedIn

MODERN CONSENSUS. “Most cosmologists today concur that our universe resembles an FRW universe, one that is infinite, has no boundary and will go on expanding ad infinitum.” (FRW = Friedmann-Robertson-Walker universe). https://lnkd.in/draqjTW View in LinkedIn

“HIGHLY SYMMETRIC and empty, the 5-D antide Sitter universe is hardly like our universe existing in 4-D, filled with matter and radiation and riddled with violent events. Even if we approximate our real universe with one that has matter and radiation spread uniformly throughout, we get not an antide Sitter universe but rather a Friedmann-Robertson-Walker universe.” https://lnkd.in/draqjTW View in LinkedIn

5D VS 4D SPACETIME. “The correspondence works the other way, too. Witten has shown that a black hole in antide Sitter spacetime corresponds to hot radiation in the alternative physics operating on the bounding spacetime. The entropy of the hole--a deeply mysterious concept--equals the radiation's entropy, which is quite mundane.” https://lnkd.in/draqjTW View in LinkedIn

5D VS 4D PARTICLES. “The holographic equivalence can allow a difficult calculation in the 4-D boundary spacetime, such as the behavior of quarks and gluons, to be traded for another, easier calculation in the highly symmetric, 5-D antide Sitter spacetime.” https://lnkd.in/draqjTW View in LinkedIn

JACOB D. BEKENSTEIN has contributed to the foundation of black hole thermodynamics and to other aspects of the connections between information and gravitation. He is Polak Professor of Theoretical Physics at the Hebrew University of Jerusalem, a member of the Israel Academy of Sciences and Humanities, and a recipient of the Rothschild and the Israel prizes. Bekenstein dedicates this article to John Archibald Wheeler (his Ph.D. supervisor 30 years ago). https://lnkd.in/draqjTW View in LinkedIn

Hazy days of summer with high contrasts of light and shadow, blazing heat and relief. View in LinkedIn

GOD IS A GEOMETER. “Tool-use, with its Subject (the tool), Verb (movement of the tool), and Object (the workpiece), and manipulation of mental images, is an extension of the sentence. The sense of truth and falsity shares a common source with the right and wrong answers of arithmetic.” (The human mind’s origins in geometry, an unusual viewpoint) https://lnkd.in/drepKdh View in LinkedIn

THE WORLD AS INFO. “Holography may be a guide to a better theory. What is the fundamental theory like? The chain of reasoning involving holography suggests to some, notably Lee Smolin of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, that such a final theory must be concerned not with fields, not even with spacetime, but rather with information exchange among physical processes. If so, the vision of information as the stuff the world is made of will have found a worthy embodiment.” https://lnkd.in/draqjTW View in LinkedIn

ENTROPY. “Furthermore, even if the infinity is tamed, the mysterious dependence of information on surface area must be somehow accommodated.” https://lnkd.in/draqjTW View in LinkedIn