There’s actually no empirical difference between those two cases. There is if there was a true superposition, but there isn’t in the cat case. It’s been demonstrated with macroscopic objects, but under conditions which would kill any cat (such as being in a vacuum and almost 0°K). — noAxioms
This is nonsense. You have a reference to such a crazy definition from a consensus physics reference from the last century? What even is uniform existence? That a body must be the same everywhere? A carrot cannot taper? I presume you to be an absolutist and maybe get your definitions from the sites supporting such, but this is not the consensus definition as used by physicists. — noAxioms
The laws of Newtonian dynamics provide a simple definition: an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions. — https://plato.stanford.edu/entries/spacetime-iframes/#QuasInerFramNewtCoroV\
No, not at all. I can for example reference the inertial frame of Earth when referencing the twins scenario. No duration is specified or necessary when identifying that frame. — noAxioms
There were lots of basic topics covered, down to interpretations of time near the bottom, but I didn’t see quantum interpretations mentioned at all, which requires probably a whole separate course — noAxioms
The problem with vectors is that they represent things (forces and movements) with one dimensional straight lines, when we know that in reality these things act in a multidimensional way. — Metaphysician Undercover
The issue is, as I said at the beginning, the straight line of a vector does not accurately represent a multidimensional activity which has curves inherent within every infinitesimal point. So real movement from one infinitesimal space to the next is not accurately represented with straight vectors, and the longer the vectors are, the more the inaccuracy is magnified. — Metaphysician Undercover
Oh my. Whereas the simplest vector spaces (in R^2 or C) have vectors which can be represented by little arrows in the Euclidean or complex planes, most vectors in QM go far beyond this and cannot be so described. See Hilbert space. — jgill
I can still express the length √2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable. — noAxioms
Actual numbers in nature (such as the ratio of the half lives of two specific isotopes) are not in this countable set. I have a hard time with a model of the universe that requires only the former sort of number, such as one would get in a simulation. Actual numbers are more analog, like ‘so big’ with your hands held apart. — noAxioms
Going to get back to you on this one. Interesting read, but the introduction is already full of interpretation dependent assumptions, such as counterfactual statements. I will look at it from my relational perspective which doesn’t make those assumptions, but thus far I’ve not read enough to really comment on it. — noAxioms
Another option is to give up observer independence completely by considering facts only relative to observers [24], or by adopting an interpretation such as QBism, where quantum mechanics is just a tool that captures an agent’s subjective prediction of future measurement outcomes [25]. — Experimental test of local observer-independence - Proietti, et al., 2019
The use of "inner" makes it sound like these are properties internal to the point. In reality they are how the point relates to other points (by means of vectors), therefore external relations. — Metaphysician Undercover
then the physicist will continue into that theoretical fantasy land, a fictional world requiring the assumption of "virtual particles", in a pointless attempt to maintain the representation of mass at a point. — Metaphysician Undercover
the point does not provide a very truthful, or even accurate representation of a body, which really exists in the area around the point — Metaphysician Undercover
Lattice field theory avoids virtual particles, which are mathematical conveniences. — jgill
I'm curious how you would express what you have said in the context of field theory. — jgill
I think the issue with the lattice representation is that the designation of a quantum (discrete unit) of space is completely arbitrary, not based on any real attributes of space itself — Metaphysician Undercover
I'm not an observer, no, I'm definitely not. — Numerius Negedius
Does the observer have to be conscious or are there non-living "observers"? — Agent Smith
what am I missing then? If you can explain me, I would be so much appreciated — javi2541997
What are the "real" attributes of space? — jgill
OK, maybe, but it’s a very different definition. Is there an example of something that isn’t in this set? Maybe my prior example of the half life of carbon 14. I called it a representable number, and I suppose that if you can represent it, you can compute it as per your definition, and if you can’t compute it, you also cannot represent it, except I think I just did in my example.I can still express the length √2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable.— noAxioms
Yes, computable numbers. — Andrew M
I think I just represented it with such words, so I’ll answer my own question.Do we know that "the ratio of the half lives of two specific isotopes" isn't representable? — noAxioms
Does the statement above apply to non-classical physical systems? Can it simulate say a quantum computer to arbitrary precision? Another interesting note about the above statement is that a Turing machine cannot simulate itself, which is not a violation of the statement.That question seems relevant to the physical Church-Turing thesis (Church-Turing-Deutsch principle) which says that any bounded physical system can be simulated by a Turing machine to any desired precision. — Andrew M
OK, I said I’d get back on this one. I admittedly get lost in the complex examples, but I did at least want to comment on some of the assumptions the paper is making, assumptions which are very interpretation dependent. The topic here is about how MWI would handle it.A related test has been carried out at a microscopic level (using photons instead of AI's) where it was shown that physical collapse does not occur. — Andrew M
A.Smith, this is also relevant to your question. No, no experiment has demonstrated a living thing to have a special role.Does the observer have to be conscious or are there non-living "observers"? — Agent Smith
An observer is apparently a clerk, reacting to a measurement and putting into some non-volatile state. A digital camera for instance has a CCD (the measurement device) and an SD card (the persistent state) and a bit of circuitry (the observer) to move the data from the CCD to the SD card. This is nothing particularly special, but they give it a very special role in the paper:let us first clarify our notion of an observer. Formally, an observation is the act of extracting and storing information about an observed system. Accordingly, we define an observer as any physical system that can extract information from another system by means of some interaction, and store that information in a physical memory. — PPGBKBRF
It seems that they’ve given this clerical role some special metaphysical status, that of arbiter of what is fact or not, and also the only physical process which is probabilistic instead of deterministic. I’m not sure if they’re asserting these things and strawman arguments to knock down or they’re actually pushing this.The observer’s role as final arbiter of universal facts [1] was imperilled by the advent of 20th century science.
…
in quantum theory, all physical processes are continuous and deterministic, except for observations, which are proclaimed to be instantaneous and probabilistic. — PPGBKBRF
This is suddenly a relational wording of the situation due to the addition of ‘from the friend’s PoV’. Suddenly the ‘observation’ doesn’t make anything a universal fact at all, as evidenced by Wigner’s measurement:According to quantum theory, the friend randomly observes one of the two possible outcomes in every run of the experiment. The friend’s record, h or v, can be stored in one of two possible orthogonal states of some physical memory, labeled either |“photon is h”> or |“photon is v”>, and constitutes a “fact” from the friend’s point of view. — PPGBKBRF
Rightly so. There are no facts, just points of view. The friend is measured to be in superposition of having recorded one fact and of having recorded a different fact, pretty much demonstrating a lack of universal facts. Establishment of those universal facts were the only apparent role of these observers, so with that neatly shot down, the observer plays no role at all.Wigner can now perform an interference experiment in an entangled basis containing the states of Eq. (1) to verify that the photon and his friend’s record are indeed in a superposition—a “fact” from his point of view — PPGBKBRF
Thank you for the definitions. The article you referenced makes no mention of ‘uniform existence’, ‘unchanging presence’ so it helps to define these terms up front if you’re going to use them."Uniform existence" is having an unchanging presence, as in not being acted upon by forces; what is described by Newton's first law, which is commonly referred to as "the law of inertia". — Metaphysician Undercover
A good definition, and it comes from the top of the article, not section 1.7 to which you linked. That section deals with pre-20th-century handling of what is now called accelerated reference frames. It even includes an early form of the equivalence principle as worded by Newton.Check the Stanford article I previously referenced:
“an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions.”
I can still express the length √2 with two characters, a very finite state. Humans deal only with such representable numbers, and they’re countable.— noAxioms
Yes, computable numbers.
— Andrew M
OK, maybe, but it’s a very different definition. Is there an example of something that isn’t in this set? — noAxioms
"That question seems relevant to the physical Church-Turing thesis (Church-Turing-Deutsch principle) which says that any bounded physical system can be simulated by a Turing machine to any desired precision."
— Andrew M
Does the statement above apply to non-classical physical systems? Can it simulate say a quantum computer to arbitrary precision? — noAxioms
Another interesting note about the above statement is that a Turing machine cannot simulate itself, which is not a violation of the statement. — noAxioms
OK, I said I’d get back on this one. I admittedly get lost in the complex examples, but I did at least want to comment on some of the assumptions the paper is making, assumptions which are very interpretation dependent. The topic here is about how MWI would handle it. — noAxioms
An observer is apparently a clerk, reacting to a measurement and putting into some non-volatile state. A digital camera for instance has a CCD (the measurement device) and an SD card (the persistent state) and a bit of circuitry (the observer) to move the data from the CCD to the SD card. — noAxioms
This is nothing particularly special, but they give it a very special role in the paper:
The observer’s role as final arbiter of universal facts [1] was imperilled by the advent of 20th century science.
…
in quantum theory, all physical processes are continuous and deterministic, except for observations, which are proclaimed to be instantaneous and probabilistic.
— PPGBKBRF
It seems that they’ve given this clerical role some special metaphysical status, that of arbiter of what is fact or not, and also the only physical process which is probabilistic instead of deterministic. I’m not sure if they’re asserting these things and strawman arguments to knock down or they’re actually pushing this. — noAxioms
for the no-go theorem we tested here [4] it is sufficient that [the observers] perform a measurement and record the outcome. — Experimental test of local observer-independence - Proietti, et al., 2019
Modulo the potential loopholes and accepting the photons’ status as observers, the violation of inequality (2) implies that at least one of the three assumptions of free choice, locality, and observer-independent facts must fail." — Experimental test of local observer-independence - Proietti, et al., 2019
Wigner can now perform an interference experiment in an entangled basis containing the states of Eq. (1) to verify that the photon and his friend’s record are indeed in a superposition—a “fact” from his point of view
— PPGBKBRF
Rightly so. There are no facts, just points of view. The friend is measured to be in superposition of having recorded one fact and of having recorded a different fact, pretty much demonstrating a lack of universal facts. Establishment of those universal facts were the only apparent role of these observers, so with that neatly shot down, the observer plays no role at all.
This pretty much answers the topic title here, at least from that article’s description. Facts are relative to a system state, which makes it ‘observer dependent’ if you want to apply the label of ‘observer’ to a specific system state, but I see no point in the special label. — noAxioms
"Uniform existence" is having an unchanging presence, as in not being acted upon by forces; what is described by Newton's first law, which is commonly referred to as "the law of inertia". Check the Stanford article I previously referenced:
The laws of Newtonian dynamics provide a simple definition: an inertial frame is a reference-frame with a time-scale, relative to which the motion of a body not subject to forces is always rectilinear and uniform, accelerations are always proportional to and in the direction of applied forces, and applied forces are always met with equal and opposite reactions.
— https://plato.stanford.edu/entries/spacetime-iframes/#QuasInerFramNewtCoroV\ — Metaphysician Undercover
It's still weird to me that the observer is a necessary component of making sense of MWI, since decohered branches are still in universal superposition, which is what infinite De sitter space will become, except without the decohered observers. — Marchesk
... It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured. It will then decohere (become entangled with the wider environment), which causes a splitting of the wave function into separate branches.
It’s key that the macroscopic device in question starts out far from equilibrium. Otherwise it would already be entangled with everything, and the measurement/splitting process couldn’t occur.
...
The informal notion of an “observer” requires a macroscopic system that is out of equilibrium. In de Sitter space, everything is in equilibrium. — Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll
The standard story says that the inflaton field undergoes quantum fluctuations, which then get imprinted as fluctuations in density. What we’re saying is that the inflaton doesn’t actually “fluctuate,” it’s just in some calculable quantum state. But there’s nothing “observing” it, causing decoherence and branching of the wave function. At least, not while inflation is going on. But when inflation ends, the universe reheats into a hot plasma of matter and radiation. That actually does lead to decoherence and branching — the microscopic states of the plasma provide an environment that becomes entangled with the large-scale fluctuations of the inflaton, effectively measuring it and collapsing the wave function. So in our picture, all of the textbook predictions for inflation perturbations remain unchanged. — Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll
It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured — Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll
It has nothing to do with consciousness or intelligence (of course). An “observation” in quantum mechanics happens whenever any out-of-equilibrium macroscopic system becomes entangled with the quantum system being measured
— Squelching Boltzmann Brains (And Maybe Eternal Inflation) - Sean Carroll
That is an a priori assertion, but which really could only ever be validated by observation. — Wayfarer
Get involved in philosophical discussions about knowledge, truth, language, consciousness, science, politics, religion, logic and mathematics, art, history, and lots more. No ads, no clutter, and very little agreement — just fascinating conversations.