Quantum paradox points to shaky foundations of reality
https://www.sciencemag.org/news/2020/08/...ns-reality
INTRO: Nearly 60 years ago, the Nobel prize–winning physicist Eugene Wigner captured one of the many oddities of quantum mechanics in a thought experiment. He imagined a friend of his, sealed in a lab, measuring a particle such as an atom while Wigner stood outside. Quantum mechanics famously allows particles to occupy many locations at once—a so-called superposition—but the friend’s observation “collapses” the particle to just one spot. Yet for Wigner, the superposition remains: The collapse occurs only when he makes a measurement sometime later. Worse, Wigner also sees the friend in a superposition. Their experiences directly conflict.
Now, researchers in Australia and Taiwan offer perhaps the sharpest demonstration that Wigner’s paradox is real. In a study published this week in Nature Physics, they transform the thought experiment into a mathematical theorem that confirms the irreconcilable contradiction at the heart of the scenario. The team also tests the theorem with an experiment, using photons as proxies for the humans. Whereas Wigner believed resolving the paradox requires quantum mechanics to break down for large systems such as human observers, some of the new study’s authors believe something just as fundamental is on thin ice: objectivity. It could mean there is no such thing as an absolute fact, one that is as true for me as it is for you.
“It’s a bit disconcerting,” says co-author Nora Tischler of Griffith University. “A measurement outcome is what science is based on. If somehow that’s not absolute, it’s hard to imagine.” For physicists who have dismissed thought experiments like Wigner’s as interpretive navel gazing, the study shows the contradictions can emerge in actual experiments, says Dustin Lazarovici, a physicist and philosopher at the University of Lausanne who was not part of the team. “The paper goes to great lengths to speak the language of those who have tried to merely discuss foundational issues away and may thus compel at least some to face up to them,” he says... (MORE)
RELATED (Scientific American): This Twist on Schrödinger’s Cat Paradox Has Major Implications for Quantum Theory
Twistors: A New Direction For A Unified Theory
https://www.science20.com/tommaso_dorigo...ory-250029
EXCERPT: Twistor theory is a mathematical construction that dates back to the sixties [...] Funnily enough, it has now been brought to the fore by Peter Woit ... In his book [Not Even Wrong] Woit exposed the nudity of ... string theory ... the theory was most likely rather an intriguing piece of mathematics than anything connected with physical reality ... Maybe sad, but true, Woit's assessment has stood the test of time.
But Woit is also very well known for his outstanding blog, which has been up for over 15 years without a glitch. [...] Twistor spaces are the topic of the blog post at Peter Woit's site. There, he explains how he got enthused by their properties, as he saw in particular that they can be brought to have a deep connection with the internal symmetry properties of fundamental fields.
An internal symmetry is a symmetry that is not realized in spacetime, but in some other "internal space" that describes the properties of the object. Electric charge, for instance, is a quantity that describes the symmetry properties of particles withstanding electromagnetic interactions. E.g., if you change all electric charges of a system of particles, whatever that is, by switching positive ones to negative ones and vice-versa, you get a system that behaves exactly in the same way.
Because fundamental fields (the particles the world is made of, and the particles that propagate the interactions between them, and ultimately keep our world together) possess several distinct internal symmetries, it goes without saying that any mathematical structure that can describe the transformation properties of the connected attributes of the fields should get our attention, if we are about trying to decypher the inner fabric of our universe.
In his post Woit describes much better than I could do here why twistors might be a key to the construction of a theory of everything, so I suggest that you visit his post if you want to know more. If you are happy with my sound bytes, the most intriguing thing is that the twistor space "contains" both the Minkowsky space of space-time transformations and the Euclidean space as "slices" of its complex structure... (MORE - details)
https://www.sciencemag.org/news/2020/08/...ns-reality
INTRO: Nearly 60 years ago, the Nobel prize–winning physicist Eugene Wigner captured one of the many oddities of quantum mechanics in a thought experiment. He imagined a friend of his, sealed in a lab, measuring a particle such as an atom while Wigner stood outside. Quantum mechanics famously allows particles to occupy many locations at once—a so-called superposition—but the friend’s observation “collapses” the particle to just one spot. Yet for Wigner, the superposition remains: The collapse occurs only when he makes a measurement sometime later. Worse, Wigner also sees the friend in a superposition. Their experiences directly conflict.
Now, researchers in Australia and Taiwan offer perhaps the sharpest demonstration that Wigner’s paradox is real. In a study published this week in Nature Physics, they transform the thought experiment into a mathematical theorem that confirms the irreconcilable contradiction at the heart of the scenario. The team also tests the theorem with an experiment, using photons as proxies for the humans. Whereas Wigner believed resolving the paradox requires quantum mechanics to break down for large systems such as human observers, some of the new study’s authors believe something just as fundamental is on thin ice: objectivity. It could mean there is no such thing as an absolute fact, one that is as true for me as it is for you.
“It’s a bit disconcerting,” says co-author Nora Tischler of Griffith University. “A measurement outcome is what science is based on. If somehow that’s not absolute, it’s hard to imagine.” For physicists who have dismissed thought experiments like Wigner’s as interpretive navel gazing, the study shows the contradictions can emerge in actual experiments, says Dustin Lazarovici, a physicist and philosopher at the University of Lausanne who was not part of the team. “The paper goes to great lengths to speak the language of those who have tried to merely discuss foundational issues away and may thus compel at least some to face up to them,” he says... (MORE)
RELATED (Scientific American): This Twist on Schrödinger’s Cat Paradox Has Major Implications for Quantum Theory
Twistors: A New Direction For A Unified Theory
https://www.science20.com/tommaso_dorigo...ory-250029
EXCERPT: Twistor theory is a mathematical construction that dates back to the sixties [...] Funnily enough, it has now been brought to the fore by Peter Woit ... In his book [Not Even Wrong] Woit exposed the nudity of ... string theory ... the theory was most likely rather an intriguing piece of mathematics than anything connected with physical reality ... Maybe sad, but true, Woit's assessment has stood the test of time.
But Woit is also very well known for his outstanding blog, which has been up for over 15 years without a glitch. [...] Twistor spaces are the topic of the blog post at Peter Woit's site. There, he explains how he got enthused by their properties, as he saw in particular that they can be brought to have a deep connection with the internal symmetry properties of fundamental fields.
An internal symmetry is a symmetry that is not realized in spacetime, but in some other "internal space" that describes the properties of the object. Electric charge, for instance, is a quantity that describes the symmetry properties of particles withstanding electromagnetic interactions. E.g., if you change all electric charges of a system of particles, whatever that is, by switching positive ones to negative ones and vice-versa, you get a system that behaves exactly in the same way.
Because fundamental fields (the particles the world is made of, and the particles that propagate the interactions between them, and ultimately keep our world together) possess several distinct internal symmetries, it goes without saying that any mathematical structure that can describe the transformation properties of the connected attributes of the fields should get our attention, if we are about trying to decypher the inner fabric of our universe.
In his post Woit describes much better than I could do here why twistors might be a key to the construction of a theory of everything, so I suggest that you visit his post if you want to know more. If you are happy with my sound bytes, the most intriguing thing is that the twistor space "contains" both the Minkowsky space of space-time transformations and the Euclidean space as "slices" of its complex structure... (MORE - details)