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String Theory’s Strange Second Life | Quanta Magazine

String theory has so far failed to live up to its promise as a way to unite gravity and quantum mechanics. At the same time, it has blossomed into one of the

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Edward Witten Ponders the Nature of Reality

Edward Witten reflects on the meaning of dualities in physics and math, emergent space-time, and the pursuit of a complete description of nature.

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The Power of Mirror Symmetry

Ideas that originate in particle physics have an uncanny tendency to appear in the most diverse mathematical fields. This is especially true for string theory. Its stimulating influence in mathematics will have a lasting and rewarding impact, whatever its final role in fundamental physics turns out to be. The number of disciplines that it touches is dizzying: analysis, geometry, algebra, topology, representation theory, combinatorics, probability-the list goes on and on.

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Mathematicians Measure Infinities, Find They’re Equal | Quanta Magazine

Two mathematicians have proved that two different infinities are equal in size, settling a long-standing question. Their proof rests on a surprising link

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“Gravity Alters the Quantum Nature of Particles on Earth” –What Does It Imply at Cosmological Scales? (Today’s Most Popular)

“It is quite surprising that gravity can play any role in quantum mechanics”, says Igor Pikovski, a theoretical physicist working at the Harvard-Smithsonian Center for Astrophysics:”Gravity is usually studied on astronomical scales, but it seems that it also alters the…

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"Gravity Alters the Quantum Nature of Particles on Earth" –What Does It Imply at Cosmological Scales? (Today's Most Popular)

“It is quite surprising that gravity can play any role in quantum mechanics”, says Igor Pikovski, a theoretical physicist working at the Harvard-Smithsonian Center for Astrophysics:”Gravity is usually studied on astronomical scales, but it seems that it also alters the…

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Australian Physicists Have Proved That Time Travel is Possible

Scientists from the University of Queensland have used photons (single particles of light) to simulate quantum particles travelling through time. The research is cutting edge and the results could be dramatic!

Their research, entitled “Experimental simulation of closed timelike curves “, is published in the latest issue of Nature Communications. The grandfather paradox states that if a time traveler were to go back in time, he could accidentally prevent his grandparents from meeting, and thus prevent his own birth.

However, if he had never been born, he could never have traveled back in time, in the first place. The paradoxes are largely caused by Einstein’s theory of relativity, and the solution to it, the Gödel metric.

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A Strange New Theory of How Space-Time is Emerging

“A metaphorical chip holding all the programming for our universe stores information like a quantum computer.” This is the radical insight to the foundation of our Universe developed by Mark Van Raamsdonk, a professor of theoretical physics at the University of British Columbia, that says that the world we see around us is a projection from a set of rules written in simpler, lower-dimensional physics-just as the 2D code in a computer’s memory chip creates an entire virtual 3D world. “What Mark has done is put his finger on a key ingredient of how space-time is emerging: entanglement,” says Gary Horowitz, who studies quantum gravity at the University of California Santa Barbara. Horowitz says this idea has changed how people think about quantum gravity, though it hasn’t yet been universally accepted. “You don’t come across this idea by following other ideas. It requires a strange insight,” Horowitz adds. “He is one of the stars of the younger generation.”
“We’re trying to construct a dictionary,” says Van Raamsdonk, that allows physicists to translate descriptions of our complex universe into simpler terms. If they succeed, they will have found the biggest jigsaw piece in the puzzle of a Grand Unified Theory-something that can describe all of the forces of our universe, at all scales from the atomic to the galactic. That puzzle piece is, specifically, something that can describe gravity within the framework of quantum mechanics, which governs physics on small scales. Such a unified theory is needed to explain the extreme scenarios of a black hole or the first moments of the universe.” The catacylst for Van Raamsdonk’s theory was a 1998 paper by Juan Maldacena a theoretical astrophysicist at Princeton’s Institite for Advanced studies that proposed that to understand quantum gravity through string theory, you can look instead to the much more ordinary, well-described system of quantum mechanics called quantum field theory that concluded that it seems that all the information about our complex multi-dimensional world can be described using a simpler, lower-dimensional language-just as a 3D image is projected from the 2D screen of a hologram, or a 3D computer gaming world created from a 2D memory chip. “After that, people wrote thousands of papers just testing whether that could be true,” says Van Raamsdonk. “No one has actually proven it, but we’re as certain about it as about anything in physics,” he added.

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The theory of parallel universes is not just maths – it is science that can be tested

The existence of parallel universes may seem like something cooked up by science fiction writers, with little relevance to modern theoretical physics. But the idea that we live in a “multiverse” made up of an infinite number of parallel universes has long been considered a scientific possibility – although it is still a matter of vigorous debate among physicists. The race is now on to find a way to test the theory, including searching the sky for signs of collisions with other universes.