Quantum mechanics (Jenann Ismael)

Quantum mechanics is, at least at first glance and at least in part, a mathematical machine for predicting the behaviors of microscopic particles — or, at least, of the measuring instruments we use to explore those behaviors — and in that capacity, it is spectacularly successful: in terms of power and precision, head and shoulders above any theory we have ever had. Mathematically, the theory is well understood; we know what its parts are, how they are put together, and why, in the mechanical sense (i.e., in a sense that can be answered by describing the internal grinding of gear against gear), the whole thing performs the way it does, how the information that gets fed in at one end is converted into what comes out the other. The question of what kind of a world it describes, however, is controversial; there is very little agreement, among physicists and among philosophers, about what the world is like according to quantum mechanics. Minimally interpreted, the theory describes a set of facts about the way the microscopic world impinges on the macroscopic one, how it affects our measuring instruments, described in everyday language or the language of classical mechanics. Disagreement centers on the question of what a microscopic world, which affects our apparatuses in the prescribed manner, is, or even could be, like intrinsically ; or how those apparatuses could themselves be built out of microscopic parts of the sort the theory describes.

4 thoughts on “Quantum mechanics (Jenann Ismael)

  1. shinichi Post author

    (Google Translate)

    量子力学は、少なくとも一見すると、そして少なくとも部分的には、微視的な粒子の挙動、または少なくともそれらの挙動を調査するために私たちが使用する測定機器の挙動を予測するための数学的機械であり、その能力において、それは驚くべきものです。 成功: パワーと精度の点で、これまでのどの理論よりも優れています。 数学的には、この理論はよく理解されています。 私たちは、その部品が何であるか、それらがどのように組み合わされるのか、そして機械的な意味で(つまり、歯車と歯車の内部研削を説明することで答えることができる意味で)なぜ全体がそのように動作するのかを知っています。 一方の端から入力された情報が、もう一方の端から出力される情報にどのように変換されるか。 しかし、それがどのような世界を描いているのかという問題は議論の余地があります。 量子力学によれば世界がどのようなものであるかについては、物理学者の間でも哲学者の間でもほとんど合意がありません。 最小限に解釈すると、この理論は、微視的な世界が巨視的な世界にどのように影響するか、それが私たちの測定器にどのような影響を与えるかについての一連の事実を、日常言語または古典力学の言語で説明します。 意見の相違は、所定の方法で私たちの装置に影響を与えるミクロの世界とは何なのか、あるいは本質的に何であり得るのか、あるいは、それらの装置自体が理論で説明されている種類の微細な部品からどのように構築されるのか、という問題に集中しています。

  2. shinichi Post author

    Can Physics Fuel Philosophy ? – Prof. Jenann Ismael (Dialogues on the Foundations)

    Munich Center for Quantum Science & Technology


    A chat with Prof. Jenann Ismael (John Hopkins University, Baltimore, USA) on the relation between and philosophy, the philosophical implications of quantum mechanics, free will, agency, causality, and much more.

    00:00 Intro
    02:14 Philosophy and Physics
    22:43 Quantum Entanglement, non-locality, Holism
    41:34 The Role of the Observer
    49:13 Agency and the Nature of Probabilities
    01:01:35 Agency and Causality
    01:15:56 Free Will
    01:33:49 Conclusions

    The “Dialogues on the Foundations” are a series of meetings with physicists and philosophers working on the foundations of physics, discussing topics including quantum gravity, cosmology, foundations of quantum mechanics, philosophy of physics, and more.

    The goal is to show how physicists and philosophers are re-assessing and re-shaping the fundamental bases of our understanding of the natural world and to do it through the same main activity they engage on: chatting, discussing, asking questions, suggesting answers, identifying critical points, expressing openly what is known and what is still puzzling or mysterious, hopes and excitement, doubts and confusions.

    The dialogues are part of the CAS Research Focus “Foundations of Physics” at the Center for Advanced Studies (CAS) at Ludwig-Maximilians-Universität (LMU) München, and are supported by the Munich Center for Quantum Science and Technology.
    They are hosted by Dr. Daniele Oriti, the speaker of the CAS Research Focus, and director of the research group “Quantum Gravity and Foundations of Physics” at the Arnold Sommerfeld Center for Theoretical Physics, LMU München, Germany.

  3. shinichi Post author

    Jennan Ismael – What Does Quantum Theory Mean?

    Closer To Truth


    Quantum theory may be weird—superposition and entanglement of particles that in our normal world would make no sense—but quantum theory is truly how the microworld works. What does all this weirdness mean? How to go from microworld weirdness to macroworld normalcy? Will we ever make sense out of quantum mechanics?

    in trying to get to the rudiments of reality,
    you have to start with quantum physics,
    but when i do i hear all these different interpretations
    some from scientists but many from philosophers of physics
    why are there so many interpretations of quantum physics
    it’s a science

    it’s a science
    i think one of the really exciting things about quantum physics from a philosophical point of view is
    that what the theory is at the very least is a complicated algorithm for actually not a complicated outcome of an elegantly simple algorithm
    for allowing us to predict the results of any observations or any measurements
    that we could possibly make in nature and it’s unparalleled as you know in terms of precision and testability

    so nobody doubts that quantum mechanics gets the predictions right
    but the problem is it seems like when we try to interpret the formalism by which i mean we try to understand what the world is like according to quantum mechanics
    it turns out that we can give a reconstruction of all of the predictions of quantum mechanics with completely
    different stories about what the fundamental constituents of
    of nature are like a completely different just into even intuitive terms picture of reality at the fundamental level

    and i think from a philosophical point of view that raises really interesting questions
    because it tells us that the constraints on the way the
    world is that are placed by all anything that we could possibly see are not strong enough
    to tell us

    to specify one thing

    that’s exactly right
    and not not just not just
    not just that it doesn’t specify only one thing so not just that it doesn’t give us a single um conception

    but it leaves open wildly different conceptions

    give me examples

    well for example just to use the notion closer to truth
    there’s no way of sort of even narrowing down
    the description of the way the world is
    because we have things as radically different as whatever it tells us
    which is that there’s a whole bunch of different non-spatial temporally connected branches of space-time
    that are mutually inaccessible
    or at least in the ordinary everyday way of just looking around us that couldn’t
    that we couldn’t distinguish by those means branches of reality

    another view holds that no matter there is just one world
    but things evolve in such a way that every once in a while
    there’s a discontinuous change in the state of matter
    another one holds that the world is largely classical
    in the way that we think it is
    but there is this sort of weird field in nature
    that guides the particles around
    and is largely unseen by us
    and that produces correlations between distant systems located in different parts of space
    there are even really quite wild ones
    that say what we see in everyday sort of experience is a kind of weird redundant projection of a higher higher dimensional reality
    so even space time itself is a kind of illusion

    okay you’ve given me some very wild concepts
    as we sit here on a very nice porch and beautiful trees around us
    so how do you begin to get your hands around
    that it seems like it’s
    it’s almost in principle impossible to differentiate between those

    uh to differentiate between them by doing an experiment

    even a thought experiment

    i think we need to
    well let me say one of the other exciting things about quantum mechanics
    which is that it’s forced people to do some real soul searching about the most fundamental concepts
    metaphysical concepts the nature of space and time
    the nature of causation
    then they the the criterion
    by which we individuate systems
    by which i mean how do we count systems
    we normally suppose that
    if a system is located in one part of space
    it can’t affect systems in other parts of space
    or to put it a little bit differently
    that if we see events in two parts of space
    those are two separate events um
    the alternative to that would be well
    maybe reality is kind of redundant in the way that
    when we look through the lens of a kaleidoscope
    we see multiple redundant images of what’s ultimately a
    single glass bead or located in you know a different part of the world
    so what we see is a kind of redundant image
    those are those are questions that are raised
    by quantum mechanics
    and different interpretations of quantum mechanics
    we’ll answer those in different ways
    so the question really becomes
    what are the criteria
    besides just observation
    besides just adequacy to reproducing those observations
    that would allow us to rule between them
    and i think actually
    you know there are implicit in the canons of scientific reasoning
    criteria that we employ for ruling out you know implausible descriptions
    or descriptions that are less plausible
    than other ones and those come under real pressure
    um when we you know we don’t when experiments give out

    some would claim that everything that you just said just means
    that there’s something more fundamental than quantum physics
    and that quantum physics is an emergent out of something more fundamental
    so that all of these uncertainties
    which are built into quantum mechanics will disappear
    when you get down to a more fundamental level

    right so um
    philosophers of quantum gravity hope for such a thing
    so the idea if i’m understanding you properly
    is that all of the ambiguity that we have in interpretation of quantum mechanics will ultimately be eliminated
    and it will emerge that there’s a single monolithic theory
    that speaks with a an absolutely unified voice
    and no choice about how to interpret it
    right now that’s a bit of a pipe dream
    but it is it is one that would resolve all these ambiguities
    on the other hand
    there are people um
    who will say no matter how many

    levels you go down

    there will always be that kind of
    that kind of ambiguity

    are you rooting for that?

    i’m no i’m rooting for the ultimate theory
    that leaves absolutely no question about how to interpret it


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