Dec 29, 2022 01:02 AM
How do we know the fundamental constants are constant? We don't.
https://www.space.com/are-fundamental-co...e-constant
EXCERPT (Paul Sutter): . . . Many physicists argue that having all these constants seems a little artificial. Our job as scientists is to explain as many varied phenomena as possible with as few starting assumptions as we can get away with. Physicists believe that general relativity and the Standard Model are not the end of the story, however, especially since these two theories are not compatible with each other. They suspect that there is some deeper, more fundamental theory that unites these two branches.
That more fundamental theory could have any number of fundamental constants associated with it. It could have the same set of 28 we see today. It could have its own, independent constants, with the 28 appearing as dynamic expressions of some underlying physics. It could even have no constants at all, with the fundamental theory able to explain itself in its entirety with nothing having to be added by hand.
No matter what, if our fundamental constants aren't really constant — if they happen to vary across time or space — then that would be a sign of physics beyond what we currently know. And by measuring those variations, we could get some clues as to a more fundamental theory.
And physicists have devised a number of experiments to test the constancy of those constants... (MORE - missing details)
What is the true nature of our quantum reality?
https://bigthink.com/starts-with-a-bang/...m-reality/
EXCERPTS (Ethan Siegel): . . . Even in strong gravitational fields or close to the speed of light, Einstein’s extensions of Newton’s theories enabled the same outcome: provide the initial, physical conditions to arbitrary accuracy and you can know what the outcome, at any point in the future, is going to be. Until the end of the 19th century, all of our best physical theories describing the Universe followed this path.
[...] Why did nature appear to behave this way? Because the rules that governed it — our best theories that we had concocted to describe what we measure and observe — all obeyed the same sets of rules.
The quantum nature of the Universe tells us that certain quantities have an inherent uncertainty built into them, and that pairs of quantities have their uncertainties related to one another. There is no evidence for a more fundamental reality with hidden variables that underlies our observable, quantum Universe.
[...] It wasn’t so surprising that the Universe was made of indivisible, fundamental units: quanta, like quarks, electrons, or photons. What was surprising is that these individual quanta didn’t behave like Newton’s particles: with well-defined positions, momenta, and angular momenta. Instead, these quanta behaved like waves — where you could compute probability distributions for their outcomes — but making a measurement would only ever give you one specific answer, and you can never predict which answer you’ll get for an individual measurement.
[...] For generations, this puzzle has stymied almost everyone who’s tried to make sense of it. Somehow, it seems like the outcome of a scientific experiment is fundamentally tied to whether we make a specific measurement or not. This has been called “the measurement problem” in quantum physics, and has been the subject of many essays, opinions, interpretations, and declarations from physicists and laypersons alike.
It seems only natural to ask what seems like a more fundamental question: what is really going on, objectively, behind-the-scenes, to explain what we observe in an observer-independent fashion?
[...] But pinning down the behavior of nature under all sorts of circumstances is very different than assuming there even is some sort of objective reality that exists, deterministically, independent of any observer or key interaction.
Reality, if you want to call it that, isn’t some objective existence that goes beyond what’s measurable or observable. In physics, as I’ve written before, describing what is observable and measurable in the most complete and accurate way possible is our loftiest aspiration. By devising a theory where quantum operators act on quantum wavefunctions, we gained the ability to accurately compute the probability distribution of whatever outcomes might possibly occur.
For most physicists, this is enough. But you can impose a set of assumptions atop these equations, and come up with a set of different interpretations of quantum mechanics:
Frustratingly, all of these interpretations, plus others, are experimentally indistinguishable from one another. There is no experiment we have yet been able to design or perform that discerns one of these interpretations from another, and therefore they are physically identical. The idea that there is a fundamental, objective, observer-independent reality is an assumption with no evidence behind it, just thousands upon thousands of years of our intuition telling us “It should be so.”
[...] Understanding the Universe isn’t about revealing a true reality, divorced from observers, measurements, and interactions. The Universe could exist in such a fashion where that’s a valid approach, but it could equally be the case that reality is inextricably interwoven with the act of measurement, observation, and interaction at a fundamental level.
The key, if you want to further your understanding of the Universe, is to find an experimental test that will discern one interpretation from another, thereby either ruling it out or elevating it above the others. Thus far, only interpretations that demand local realism (with some level of determinism thrown in there) have been ruled out, while the remainder are all untested; choosing between them is exclusively a matter of aesthetics.
In science, it is not up to us to declare what reality is and then contort our observations and measurements to conform to our assumptions. Instead, the theories and models that enable us to predict what we’ll observe and/or measure to the greatest accuracy, with the greatest predictive power, and zero unnecessary assumptions, are the ones that survive. It’s not a problem for physics that reality looks puzzling and bizarre; it’s only a problem if you demand that the Universe deliver something beyond what reality provides... (MORE - missing details)
https://www.space.com/are-fundamental-co...e-constant
EXCERPT (Paul Sutter): . . . Many physicists argue that having all these constants seems a little artificial. Our job as scientists is to explain as many varied phenomena as possible with as few starting assumptions as we can get away with. Physicists believe that general relativity and the Standard Model are not the end of the story, however, especially since these two theories are not compatible with each other. They suspect that there is some deeper, more fundamental theory that unites these two branches.
That more fundamental theory could have any number of fundamental constants associated with it. It could have the same set of 28 we see today. It could have its own, independent constants, with the 28 appearing as dynamic expressions of some underlying physics. It could even have no constants at all, with the fundamental theory able to explain itself in its entirety with nothing having to be added by hand.
No matter what, if our fundamental constants aren't really constant — if they happen to vary across time or space — then that would be a sign of physics beyond what we currently know. And by measuring those variations, we could get some clues as to a more fundamental theory.
And physicists have devised a number of experiments to test the constancy of those constants... (MORE - missing details)
What is the true nature of our quantum reality?
https://bigthink.com/starts-with-a-bang/...m-reality/
EXCERPTS (Ethan Siegel): . . . Even in strong gravitational fields or close to the speed of light, Einstein’s extensions of Newton’s theories enabled the same outcome: provide the initial, physical conditions to arbitrary accuracy and you can know what the outcome, at any point in the future, is going to be. Until the end of the 19th century, all of our best physical theories describing the Universe followed this path.
[...] Why did nature appear to behave this way? Because the rules that governed it — our best theories that we had concocted to describe what we measure and observe — all obeyed the same sets of rules.
- The Universe is local, which means that an event or interaction can only affect its environment in a way that’s limited by the speed limit of anything propagating through the Universe: the speed of light.
- The Universe is real, which means that certain physical quantities and properties (of particles, systems, fields, etc.) exist independent of any observer or measurements.
- The Universe is deterministic, which means that if you set your system up in one particular configuration, and you know that configuration exactly, you can perfectly predict what the state of your system is going to be at an arbitrary amount of time into the future.
The quantum nature of the Universe tells us that certain quantities have an inherent uncertainty built into them, and that pairs of quantities have their uncertainties related to one another. There is no evidence for a more fundamental reality with hidden variables that underlies our observable, quantum Universe.
[...] It wasn’t so surprising that the Universe was made of indivisible, fundamental units: quanta, like quarks, electrons, or photons. What was surprising is that these individual quanta didn’t behave like Newton’s particles: with well-defined positions, momenta, and angular momenta. Instead, these quanta behaved like waves — where you could compute probability distributions for their outcomes — but making a measurement would only ever give you one specific answer, and you can never predict which answer you’ll get for an individual measurement.
[...] For generations, this puzzle has stymied almost everyone who’s tried to make sense of it. Somehow, it seems like the outcome of a scientific experiment is fundamentally tied to whether we make a specific measurement or not. This has been called “the measurement problem” in quantum physics, and has been the subject of many essays, opinions, interpretations, and declarations from physicists and laypersons alike.
It seems only natural to ask what seems like a more fundamental question: what is really going on, objectively, behind-the-scenes, to explain what we observe in an observer-independent fashion?
[...] But pinning down the behavior of nature under all sorts of circumstances is very different than assuming there even is some sort of objective reality that exists, deterministically, independent of any observer or key interaction.
Reality, if you want to call it that, isn’t some objective existence that goes beyond what’s measurable or observable. In physics, as I’ve written before, describing what is observable and measurable in the most complete and accurate way possible is our loftiest aspiration. By devising a theory where quantum operators act on quantum wavefunctions, we gained the ability to accurately compute the probability distribution of whatever outcomes might possibly occur.
For most physicists, this is enough. But you can impose a set of assumptions atop these equations, and come up with a set of different interpretations of quantum mechanics:
- Is the quantum wavefunction defining these particles physically meaningless, until the moment you make a measurement? (Copenhagen interpretation.)
- Do all possible outcomes actually occur, requiring an infinite number of parallel Universes? (Many-worlds interpretation.)
- Can you imagine reality as an infinite number of identically prepared systems, and the act of measurement as the act of choosing which one represents our reality? (Ensemble interpretation.)
- Or do particles always exist as absolutes, with real and unambiguous positions, where deterministic “pilot waves” guide them in a non-local manner? (de Broglie-Bohm/Pilot wave interpretation.)
Frustratingly, all of these interpretations, plus others, are experimentally indistinguishable from one another. There is no experiment we have yet been able to design or perform that discerns one of these interpretations from another, and therefore they are physically identical. The idea that there is a fundamental, objective, observer-independent reality is an assumption with no evidence behind it, just thousands upon thousands of years of our intuition telling us “It should be so.”
[...] Understanding the Universe isn’t about revealing a true reality, divorced from observers, measurements, and interactions. The Universe could exist in such a fashion where that’s a valid approach, but it could equally be the case that reality is inextricably interwoven with the act of measurement, observation, and interaction at a fundamental level.
The key, if you want to further your understanding of the Universe, is to find an experimental test that will discern one interpretation from another, thereby either ruling it out or elevating it above the others. Thus far, only interpretations that demand local realism (with some level of determinism thrown in there) have been ruled out, while the remainder are all untested; choosing between them is exclusively a matter of aesthetics.
In science, it is not up to us to declare what reality is and then contort our observations and measurements to conform to our assumptions. Instead, the theories and models that enable us to predict what we’ll observe and/or measure to the greatest accuracy, with the greatest predictive power, and zero unnecessary assumptions, are the ones that survive. It’s not a problem for physics that reality looks puzzling and bizarre; it’s only a problem if you demand that the Universe deliver something beyond what reality provides... (MORE - missing details)