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.
Quantum mechanics
by Jenann Ismael
Stanford Encyclopedia of Philosophy (2008)
https://philpapers.org/rec/ISMQM
(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。
Can Physics Fuel Philosophy ? – Prof. Jenann Ismael (Dialogues on the Foundations)
Munich Center for Quantum Science & Technology
https://youtu.be/c2GgI-Ds58k?si=l-G6D_WCEbU-4B1x
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.
Jennan Ismael – What Does Quantum Theory Mean?
Closer To Truth
https://youtu.be/0KLnIthdCLQ?si=m22UhH4YO62vRRsm
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?
Jennan,
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
um
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
yeah
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
yeah