geordief Posted June 6, 2021 Share Posted June 6, 2021 (edited) Would I be right to understand that this is a description of the impossibility of knowing the simultaneous position and momentum of a particle? If it is not an example of the "how not why" question could I ask why (or how) this is the case? Is this an observer related phenomenon or is it the case that the particle itself cannot actually be in a particular place with a particular momentum? (as applied to a particular frame of reference if that does not in itself imply an observer) I wanted to post in this thread https://www.scienceforums.net/topic/125204-life-was-inevitable/?do=findComment&comment=1178225 but thought it was better to start a new thread...... Edited June 6, 2021 by geordief Link to comment Share on other sites More sharing options...
swansont Posted June 6, 2021 Share Posted June 6, 2021 Quote Would I be right to understand that this is a description of the impossibility of knowing the simultaneous position and momentum of a particle? It applies to any pair of conjugate variables, so in QM it includes energy & time, and angular momentum & angular position as well. These variables don’t commute, so the order you do the operation matters. Quote If it is not an example of the "how not why" question could I ask why (or how) this is the case? Is this an observer related phenomenon or is it the case that the particle itself cannot actually be in a particular place with a particular momentum? (as applied to a particular frame of reference if that does not in itself imply an observer) It’s inherent in QM i.e. it’s in the math. These variables are fourier transforms of each other. The observer effect is a distinct phenomenon edit: more detail here - https://www.forbes.com/sites/startswithabang/2017/08/12/ask-ethan-where-does-quantum-uncertainty-come-from/?sh=60c0a134794e 1 Link to comment Share on other sites More sharing options...
exchemist Posted June 6, 2021 Share Posted June 6, 2021 (edited) 6 hours ago, geordief said: Would I be right to understand that this is a description of the impossibility of knowing the simultaneous position and momentum of a particle? If it is not an example of the "how not why" question could I ask why (or how) this is the case? Is this an observer related phenomenon or is it the case that the particle itself cannot actually be in a particular place with a particular momentum? (as applied to a particular frame of reference if that does not in itself imply an observer) I wanted to post in this thread https://www.scienceforums.net/topic/125204-life-was-inevitable/?do=findComment&comment=1178225 but thought it was better to start a new thread...... To give a less mathematical response, it is the latter. For a QM entity to be in an exact place with an exact momentum is just not something that is even defined, in QM. The uncertainty is intrinsic to nature. From reading Carlo Rovelli's "Helgoland", it seems the "relational interpretation" of QM in effect denies that a QM entity even has any properties on a continuous basis. According to this view, all properties become manifest only in the course of interactions involving the QM system in question. In between interactions, it is not necessary to assume that it has any properties at all. The wave function (when the QM operator for a property is applied to it) tells you what range of values of the property the system may manifest when it interacts. Tying properties to interactions gets rid of the tiresome issue of "the observer", which has led all sorts of people astray over the years, even sometimes to the extent of speculating that QM gives a special place to conscious observers. This last is something that has spawned an entire industry of quantum woo (Deepak Chopra et.al.). But, on the contrary, any "observation" necessarily requires an interaction. It is the interaction that counts, not an act of observation. The further implication of this is that what we call "reality" is made up of the interactions going on all the time between QM entities. Which is not as crazy as it sounds. After all, something only provides evidence that it exists when it interacts with something else. Classically, we interpolate between interactions by assuming that objects possess properties with defined values all the time, in a continuous manner. But in QM it seems the only thing that unambiguously persists is the wave function, which represents the potential properties exhibited when an interaction "collapses" it. This, at least is my understanding. I find it elegant, as it seems to resolve a number of the paradoxes that QM throws up. Edited June 6, 2021 by exchemist 1 Link to comment Share on other sites More sharing options...
geordief Posted June 7, 2021 Author Share Posted June 7, 2021 (edited) 15 hours ago, exchemist said: To give a less mathematical response, it is the latter. For a QM entity to be in an exact place with an exact momentum is just not something that is even defined, in QM. The uncertainty is intrinsic to nature. From reading Carlo Rovelli's "Helgoland", it seems the "relational interpretation" of QM in effect denies that a QM entity even has any properties on a continuous basis. According to this view, all properties become manifest only in the course of interactions involving the QM system in question. In between interactions, it is not necessary to assume that it has any properties at all. The wave function (when the QM operator for a property is applied to it) tells you what range of values of the property the system may manifest when it interacts. Tying properties to interactions gets rid of the tiresome issue of "the observer", which has led all sorts of people astray over the years, even sometimes to the extent of speculating that QM gives a special place to conscious observers. This last is something that has spawned an entire industry of quantum woo (Deepak Chopra et.al.). But, on the contrary, any "observation" necessarily requires an interaction. It is the interaction that counts, not an act of observation. The further implication of this is that what we call "reality" is made up of the interactions going on all the time between QM entities. Which is not as crazy as it sounds. After all, something only provides evidence that it exists when it interacts with something else. Classically, we interpolate between interactions by assuming that objects possess properties with defined values all the time, in a continuous manner. But in QM it seems the only thing that unambiguously persists is the wave function, which represents the potential properties exhibited when an interaction "collapses" it. This, at least is my understanding. I find it elegant, as it seems to resolve a number of the paradoxes that QM throws up. Perhaps you still remember Harold14370 from the .com site?(Dirty Harry😀 ) Some years ago I fell into the trap of asking about "events" in a GR context and was curtly dismissed by him **because I did not know what an "event" was (it is just a point on the spacetime graph,I think) Seems like those "events" I was clumsily introducing then may be the kind of thing you are talking about ; another way of describing a fundamental interaction. A kind of a phenomenological "atom" (in the historical sense where it was applied to a supposed irreducible building block of nature)? **well he was one of the leading experts on GR there then ,as well as being the Admin. Edited June 7, 2021 by geordief Link to comment Share on other sites More sharing options...
iNow Posted June 7, 2021 Share Posted June 7, 2021 40 minutes ago, geordief said: Perhaps you still remember Harold14370 from the .com site? I remember him from even before that on yet another site called Hypography. Link to comment Share on other sites More sharing options...
exchemist Posted June 7, 2021 Share Posted June 7, 2021 8 hours ago, geordief said: Perhaps you still remember Harold14370 from the .com site?(Dirty Harry😀 ) Some years ago I fell into the trap of asking about "events" in a GR context and was curtly dismissed by him **because I did not know what an "event" was (it is just a point on the spacetime graph,I think) Seems like those "events" I was clumsily introducing then may be the kind of thing you are talking about ; another way of describing a fundamental interaction. A kind of a phenomenological "atom" (in the historical sense where it was applied to a supposed irreducible building block of nature)? **well he was one of the leading experts on GR there then ,as well as being the Admin. Yeah I remember him. Stroppy git, he was.😁 I rather think the relativity issue you refer to would be to do with the physicists' dismissal of the notion of time "passing", as in relativity it is just a coordinate axis and therefore doesn't have a "direction". Anyway I don't think it's related to this QM issue of interactions being what make reality tangible. Link to comment Share on other sites More sharing options...
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