Feb 25, 2022 08:19 PM
9 philosophers and scientists interpret quantum theory's famous thought experiment
https://iai.tv/articles/the-many-meaning...-auid-2057
INTRO: Contemporary versions of Erwin Schrödinger’s famous cat thought-experiment often prefer sleeping gas to cyanide. But for a cat in a box to be both asleep and awake – as opposed to the traditional cat that is both dead and alive – if considerably less gruesome, is just as strange.
Writing to Einstein in 1935, Schrödinger’s imaginary experimental set-up was designed to expose the critical flaws of the Copenhagen interpretation of quantum mechanics, which holds that quantum systems stay in a superposition of two or more states until the system interacts with an external observer. We might be able to dismiss this effect as a peculiarity of the microscopic world of atoms, but what happens when that world has a direct consequence on the macroscopic, everyday world of tables, chairs, and cats?
That’s what Schrödinger’s thought experiment sought to illuminate, and in the process expose the Copenhagen interpretation of quantum mechanics as absurd. It’s one thing having particles be in a state of superposition. But cats? Cats are either one thing or another, dead or alive, they can’t be both, surely.
"One can even set up quite ridiculous cases", began Erwin Schrödinger as he outlined the equipment:
Nearly 90 years later, the story of Schrödinger’s Cat still divides philosophers and physicists and gets to the heart of the big philosophical issues with interpreting quantum mechanics.
There are many contemporary versions and readings of the thought-experiment and its lasting implications. Some seem to restore order to a world made topsy turvy by quantum mechanics. Others, which see the creation of multiple cats in multiple universes, might be said to make the original ‘ridiculous case’ look rather mundane.
Here is a selection of the many meanings of Schrödinger’s Cat from some of our favourite thinkers... (MORE - details)
COVERED:
Amanda Gefter on Schrödinger's QBist cat
Sheldon Goldstein on The Bohmian view
Jenann Ismael on the possibility of knowledge
Chiara Marletto on the counterfactual essence of Schrödinger’s cat
Tim Maudlin on Objective Collapse and Hidden Variables
Alyssa Ney on Wave Function Realism
Tim Palmer on Superdeterminism
Carlo Rovelli on Relational Quantum Mechanics
Lev Vaidman on Many Worlds and many cats
Is the Multiverse real? Two astrophysicists debate
https://bigthink.com/13-8/is-the-multiverse-real/
EXCERPTS: . . . We invited two astrophysicists Dr. Ethan Siegel (Starts with a Bang columnist) and Dr. Adam Frank (13.8 columnist) to engage in a debate over one of the hottest topics in astrophysics: Is the Multiverse real?
Ethan’s argument: Yes, the multiverse is real. Cosmic inflation and quantum field theory both describe the Universe. Cosmic inflation, first put forth in 1980, tells us what the Universe was like prior to the hot Big Bang in order to set it up with the conditions that we observe...
[...] Because the Universe is inherently quantum in nature, that means we should expect that whatever inflation is, it has a nature that is consistent with quantum field theory — our best and most powerful description of the Universe of particles. All the things that come along with quantum physics, like Heisenberg uncertainty and the existence of quantum fluctuations, must apply to inflation as well.
So, what happens when you put inflation and quantum field theory together? You get a series of predictions, many of which have been borne out by observations. Inflation is now widely regarded as the origin of our Universe, and those observations narrow down which classes of inflationary models remain viable. Accepting cosmic inflation and quantum field theory is the scientific consensus right now, meaning it can be considered our “starting point” upon which we build.
If cosmic inflation and quantum field theory are both correct, then the Multiverse arises as an inevitable consequence of the two, combined...
Adam’s rebuttal: No, the multiverse is not real. Ethan does a great job of summarizing both inflation and its connection to the Multiverse. [...] It is important, from my viewpoint, to understand what is happening with inflation theory — because ... It is not what I would call a theory with a capitol “T,” featuring endless points of experimental verification such that its true form has been nailed down and locked tight.
Instead, it is a class of theories with lots of wiggle room for individual instantiations. [...] This is an important point because inflation takes physics we understand at way, way lower energy scales and extrapolates them into very different kinds of conditions. ... This is one reason why there are so many flavors of inflation. We don’t even know what physical field drives inflation. ... Now this, by itself, is not a problem. Speculation and extrapolation are part of what physicists do.
But… If, in the process of extrapolating to wildly extreme regimes, you end up in dangerous (from the point of view of the epistemological underpinnings of science) territory, then I think you need to step back and ask about what might have gone wrong.
This is exactly what happens with “eternal inflation” and the Multiverse. A theory we understand in one regime (much lower energy particle accelerators) gets stretched into a very different one (10-36 of a second after the Big Bang). That extrapolation solves some problems (but not others), but it all comes at a strange cost. That cost is what I call “ontological exuberance.”
It is possible that the only way the inflation extrapolation works is to accept an infinite number of Universes that you may never ever be able to observe. But that is not good. And it is not like anything else that’s happened in the history of physics...[1]
Ethan’s response: Many predictions have been verified. Adam’s response contains some interesting food-for-thought, but there is a dubious logical gambit in there at the core of his argument, which can be paraphrased this way... (MORE - missing details)
- - - footnote - - -
[1] Actually, throughout history, "what exists" has repeatedly turned out to be larger than what humans of a particular era stingily believed. Before the 1920s, the Milky Way was considered the whole universe. That is, we have already experienced a "recent" transition to yet another "multiverse" scenario, but the terminology shift conceals such today due to "galaxies" replacing "island universes".
Etymology: "Galaxies were initially discovered telescopically and were known as spiral nebulae. Most 18th to 19th century astronomers considered them as [...] just thought of as a part of the Milky Way ... Observations using larger telescopes ... began resolving them into huge conglomerations of stars, but ... the true distances of these objects placed them well beyond the Milky Way. For this reason they were popularly called island universes, but this term quickly fell into disuse, as the word universe implied the entirety of existence. Instead, they became known simply as galaxies."
https://iai.tv/articles/the-many-meaning...-auid-2057
INTRO: Contemporary versions of Erwin Schrödinger’s famous cat thought-experiment often prefer sleeping gas to cyanide. But for a cat in a box to be both asleep and awake – as opposed to the traditional cat that is both dead and alive – if considerably less gruesome, is just as strange.
Writing to Einstein in 1935, Schrödinger’s imaginary experimental set-up was designed to expose the critical flaws of the Copenhagen interpretation of quantum mechanics, which holds that quantum systems stay in a superposition of two or more states until the system interacts with an external observer. We might be able to dismiss this effect as a peculiarity of the microscopic world of atoms, but what happens when that world has a direct consequence on the macroscopic, everyday world of tables, chairs, and cats?
That’s what Schrödinger’s thought experiment sought to illuminate, and in the process expose the Copenhagen interpretation of quantum mechanics as absurd. It’s one thing having particles be in a state of superposition. But cats? Cats are either one thing or another, dead or alive, they can’t be both, surely.
"One can even set up quite ridiculous cases", began Erwin Schrödinger as he outlined the equipment:
A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid.
If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function [wave-function] of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.
Nearly 90 years later, the story of Schrödinger’s Cat still divides philosophers and physicists and gets to the heart of the big philosophical issues with interpreting quantum mechanics.
There are many contemporary versions and readings of the thought-experiment and its lasting implications. Some seem to restore order to a world made topsy turvy by quantum mechanics. Others, which see the creation of multiple cats in multiple universes, might be said to make the original ‘ridiculous case’ look rather mundane.
Here is a selection of the many meanings of Schrödinger’s Cat from some of our favourite thinkers... (MORE - details)
COVERED:
Amanda Gefter on Schrödinger's QBist cat
Sheldon Goldstein on The Bohmian view
Jenann Ismael on the possibility of knowledge
Chiara Marletto on the counterfactual essence of Schrödinger’s cat
Tim Maudlin on Objective Collapse and Hidden Variables
Alyssa Ney on Wave Function Realism
Tim Palmer on Superdeterminism
Carlo Rovelli on Relational Quantum Mechanics
Lev Vaidman on Many Worlds and many cats
Is the Multiverse real? Two astrophysicists debate
https://bigthink.com/13-8/is-the-multiverse-real/
EXCERPTS: . . . We invited two astrophysicists Dr. Ethan Siegel (Starts with a Bang columnist) and Dr. Adam Frank (13.8 columnist) to engage in a debate over one of the hottest topics in astrophysics: Is the Multiverse real?
Ethan’s argument: Yes, the multiverse is real. Cosmic inflation and quantum field theory both describe the Universe. Cosmic inflation, first put forth in 1980, tells us what the Universe was like prior to the hot Big Bang in order to set it up with the conditions that we observe...
[...] Because the Universe is inherently quantum in nature, that means we should expect that whatever inflation is, it has a nature that is consistent with quantum field theory — our best and most powerful description of the Universe of particles. All the things that come along with quantum physics, like Heisenberg uncertainty and the existence of quantum fluctuations, must apply to inflation as well.
So, what happens when you put inflation and quantum field theory together? You get a series of predictions, many of which have been borne out by observations. Inflation is now widely regarded as the origin of our Universe, and those observations narrow down which classes of inflationary models remain viable. Accepting cosmic inflation and quantum field theory is the scientific consensus right now, meaning it can be considered our “starting point” upon which we build.
If cosmic inflation and quantum field theory are both correct, then the Multiverse arises as an inevitable consequence of the two, combined...
Adam’s rebuttal: No, the multiverse is not real. Ethan does a great job of summarizing both inflation and its connection to the Multiverse. [...] It is important, from my viewpoint, to understand what is happening with inflation theory — because ... It is not what I would call a theory with a capitol “T,” featuring endless points of experimental verification such that its true form has been nailed down and locked tight.
Instead, it is a class of theories with lots of wiggle room for individual instantiations. [...] This is an important point because inflation takes physics we understand at way, way lower energy scales and extrapolates them into very different kinds of conditions. ... This is one reason why there are so many flavors of inflation. We don’t even know what physical field drives inflation. ... Now this, by itself, is not a problem. Speculation and extrapolation are part of what physicists do.
But… If, in the process of extrapolating to wildly extreme regimes, you end up in dangerous (from the point of view of the epistemological underpinnings of science) territory, then I think you need to step back and ask about what might have gone wrong.
This is exactly what happens with “eternal inflation” and the Multiverse. A theory we understand in one regime (much lower energy particle accelerators) gets stretched into a very different one (10-36 of a second after the Big Bang). That extrapolation solves some problems (but not others), but it all comes at a strange cost. That cost is what I call “ontological exuberance.”
It is possible that the only way the inflation extrapolation works is to accept an infinite number of Universes that you may never ever be able to observe. But that is not good. And it is not like anything else that’s happened in the history of physics...[1]
Ethan’s response: Many predictions have been verified. Adam’s response contains some interesting food-for-thought, but there is a dubious logical gambit in there at the core of his argument, which can be paraphrased this way... (MORE - missing details)
- - - footnote - - -
[1] Actually, throughout history, "what exists" has repeatedly turned out to be larger than what humans of a particular era stingily believed. Before the 1920s, the Milky Way was considered the whole universe. That is, we have already experienced a "recent" transition to yet another "multiverse" scenario, but the terminology shift conceals such today due to "galaxies" replacing "island universes".
Etymology: "Galaxies were initially discovered telescopically and were known as spiral nebulae. Most 18th to 19th century astronomers considered them as [...] just thought of as a part of the Milky Way ... Observations using larger telescopes ... began resolving them into huge conglomerations of stars, but ... the true distances of these objects placed them well beyond the Milky Way. For this reason they were popularly called island universes, but this term quickly fell into disuse, as the word universe implied the entirety of existence. Instead, they became known simply as galaxies."