loop quantum gravity – Quanta Magazine

How to Understand the Universe When You’re Stuck Inside of It

Amanda Gefter — Thu, 27 Jun 2019 15:20:18 +0000

The universe is kind of an impossible object. It has an inside but no outside; it’s a one-sided coin. This Möbius architecture presents a unique challenge for cosmologists, who find themselves in the awkward position of being stuck inside the very system they’re trying to comprehend. It’s a situation that Lee Smolin has been thinking about for most of his career. A physicist at the Perimeter...

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Where Gravity Is Weak and Naked Singularities Are Verboten

Natalie Wolchover — Tue, 20 Jun 2017 16:59:58 +0000

Physicists have wondered for decades whether infinitely dense points known as singularities can ever exist outside black holes, which would expose the mysteries of quantum gravity for all to see. Singularities — snags in the otherwise smooth fabric of space and time where Albert Einstein’s classical gravity theory breaks down and the unknown quantum theory of gravity is needed — seem to always...

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String Theory Meets Loop Quantum Gravity

Sabine Hossenfelder — Tue, 12 Jan 2016 15:51:13 +0000

Eight decades have passed since physicists realized that the theories of quantum mechanics and gravity don’t fit together, and the puzzle of how to combine the two remains unsolved. In the last few decades, researchers have pursued the problem in two separate programs — string theory and loop quantum gravity — that are widely considered incompatible by their practitioners. But now some scientists...

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Theories of Everything, Mapped

Natalie Wolchover — Mon, 03 Aug 2015 15:48:51 +0000

“Ever since the dawn of civilization,” Stephen Hawking wrote in his international bestseller A Brief History of Time, “people have not been content to see events as unconnected and inexplicable. They have craved an understanding of the underlying order in the world.” In the quest for a unified, coherent description of all of nature — a “theory of everything” — physicists have unearthed the...

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In Fake Universes, Evidence for String Theory

Natalie Wolchover — Wed, 18 Feb 2015 15:38:54 +0000

Thirty years have passed since a pair of physicists, working together on a stormy summer night in Aspen, Colo., realized that string theory might have what it takes to be the “theory of everything.” “We must be getting pretty close,” Michael Green recalls telling John Schwarz as the thunder raged and they hammered away at a proof of the theory’s internal consistency, “because the gods are trying...

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