bobvanluijt
Somewhat related: a book that really helped me is
Picturing Quantum Processes
by Bob Coecke. It's a visual representation of quantum
processes, which really helped me understand the concept
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asystole
This piece looks great, adding to my ever-growing "to
read" collection on Zotero.If anyone is interested in
self-studying quantum physics, QFT for the Gifted Amateur
[1] is very well regarded.1:
https://academic.oup.com/book/36442?login=false
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> ktallett
Second this book, but you need a source before this to
study QP successfully. This requires a lot of UG maths
and physics knowledge that I think most would not
have.
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quietFerry94
That pre-determined value idea is exactly local hidden
variables, and Bell's inequality rules it out, Aspect's
1982 CHSH experiment measured the violation.
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> caturopath
To be precise, Bell's inequality rules out a local
hidden variable theory. Pilot wave theories/Bohmian
mechanics is an attempt to describe a nonlocal hidden
variable theory of quantum mechanics.
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> > antonvs
To be even more precise, it rules out hidden
variable theories that satisfy Bell locality, i.e.
the assumptions that the theorem
makes.Superdeterminism and retrocausality both
allow for local hidden variables - it's just that
they don't satisfy Bell's assumptions.
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> antonvs
If you saw that in section 15, the very next paragraph
covers Bell.
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isolli
In a podcast, Alain Aspect (Nobel Prize winner) explained
that he does use the power of visualization and his
imagination to generate new ideas, but that he always
needs to check them with actual calculations because no
mental picture can be an accurate representation of
quantum physics.
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dtj1123
We understand quantum mechanics well enough to build
machines that depend almost entirely on quantum
principles.It sounds all superior and mysterious to quote
Feynman here, but the fact is many people absolutely do
understand quantum mechanics.
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> Razengan
Or we understand only just enough to make things that
work on (and up to) the layer that we
understand.Ancient humans could build boats 5000 years
ago and expand throughout the planet, but they didn't
know about water being made up of hydrogen+oxygen, or
the tides being caused by the moon, etc.Their
calculations served them on the layer they operated
on.
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> > lloeki
> the tides being caused by the moonMostly because
people around the mediterranean sea didn't have to
care, tides being so small there. Yet the Greek
had fairly advanced models of tide
schedules.Pretty sure peoples that were
experiencing bigger tides and depended on it e.g
for fishing figured out the relationship with the
moon pretty quickly, whatever esoteric reason they
may have plastered upon it.
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lkm0
"IS QUANTUM PHYSICS CORRECT AND COMPLETE?" is reductive,
there are more quantum denominations: Copenhagen, QBism,
RQM, consistent histories, Many-worlds, Bohmian mechanics,
and various spontaneous collapse people. I might've missed
a few.
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> Synaesthesia
Yes this is a particular interest of mine, the various
interpretations of QM. Most physicists subscribe to
the Copenhagen interpretation, but I still find it has
philosophical quandaries.
He mentioned many-worlds.
Bohmian mechanics has been shown to be
inadequate.Blokhinstev's ensemble interpretation,
which I like, is unattractive to many.
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frumiousirc
I take issue with "understand". I agree QM can not be
understood in terms of everyday experience. One must build
experience, language and proper metaphor for the
understanding. For example, in the intro Ross uses the
example of explaining a waterfall to someone who never saw
it. He says that can be done but he relies on implicitly
the listener knowing what people on Earth may take for
granted. That understanding of a waterfall can only happen
if the listener already has some understanding of fluid
flow and gravity. We do, but say a newly found alien
friend from a dry environment that had never experienced
fluid flow would not have the mental building blocks to
understand it. Feynman gave a famous interview where he
said, essentially, "no, I can't explain it to you because
you are too ignorant" (he said it more politely). Going
the other direction, Physics steeped enough in quantum
theory do understand QM enough to have meaningful
discussions free (at times) of rigorous math. They do this
because they have a shared language, vocabulary, metaphor.
Sure, they must rely on math and experiment to ground that
understanding in truth but I guarantee they do not
communicate understanding (solely) in math and measurement
data.
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> charcircuit
Why can AI generate pictures of waterfalls if it has
never lived on Earth?
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chistev
"I think I can safely say that nobody understands quantum
mechanics."- Richard Feynman
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> stratos123
Whether this was even true in Feynman's time, it's
much less true now.
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> ahartmetz
I also like "If you think you understand quantum
mechanics, you don't understand quantum mechanics"
which is supposedly also from Feynman.
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> > chistev
I think it's one of those famous quotes that was
never said. The one I quoted was what he
apparently said.
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> > atemerev
Quantum _mechanics_ cannot be understood, it is
full of paradoxes. It contradicts classical EM and
special relativity, among other things. A toy
theory that was an important step to what came
later.Feynman's own QED is a part of QFT, but this
is no longer quantum mechanics. Special relativity
and quantum physics are reconciled since then.
Now, we only need to reconcile GR and QFT, but
this leap was so far beyond our attempts to scale
it. Yet, QED/QFT/SM can be "understood" as there
are fewer obvious paradoxes that plagued QM.
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ktallett
The key aspects of quantum physics can be explained very
simply. The issue is going in depth without those basics.
I often find if someone doesn't get Quantum Physics, it's
that source or you need the steps explaining more
in-depth. Often sources assume your base knowledge and
that is where many fall flat.
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bozdemir
So do the rest of us.
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phpnodejspwn
2 things to understand about science:It's useful, not
metaphysically real. (Hot take btw) This is called
Instrumentalism. The belief that it's real is called
Scientific Realism. However over and over again, science
can't cover edge cases, and we find better fitting models.
The Copernician revolution is a good example of this
dichotomy.2. Academia basically forces you to believe the
doctrine or you fail the class. From philosophy to physics
to sociology. If you read the philosopher survey, you will
find trendy things being quite high. It's a religion in
itself.Bonus 3: Philosophical Pragmatism and
Instrumentalism generally solves this, but is
intellectually a dead end. There is a reason analytic
philosophy continues despite gaping holes in linguistics
(late Wittgenstein) that ruin it. But at the same time,
best fits might be missing a new paradigm. I wish I could
tell people to ask AI to explain Hegel to understand, but
I think people need to read it themselves.Tl;dr: quantum
mechanics is the best we have. It's definitely wrong, but
it's the most useful we have.
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polotics
me neither! How does the Einstein Rosen Podosky Paradox
work? can the unknown that's being collapsed not be a
pre-determined value that therefore is not traveling
faster than the speed of light?
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> superluserdo
>can the unknown that's being collapsed not be a
pre-determined value that therefore is not traveling
faster than the speed of light?This is known as a
"hidden variable theory". People will tell you that a
local (things can only affect their immediate
surroundings) version of the theory is impossible
because it would be a violation of Bell's inequality,
but there is a loophole that requires accepting the
idea of "superdeterminism". This is the idea that
where what measurement a scientist chooses to measure
is predetermined and correlated with what the particle
being measured is going to do.So if a particle lands
on a screen according to distribution p when going
through a double slit, but with distribution p' when
one of the slits is measured at, conventional QM says
that the measurement "collapses the wave function".
But a superdeterministic local hidden variable theory
would imply that the choice of whether to measure at
the slit or not was already set in stone at the same
time that the particle "decided" which path to take to
land on the screen, more or less.
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> lkm0
One of the "coping mechanisms" on a superficial level
is to say that information cannot travel faster than
light, even if entanglement is propagated
instantaneously and measurement acts faster than
light. If Alice and Bob share an entangled pair of
spins and Alice measures it, Bob has gained no
information until Alice communicates (sublight speed)
her result. They could've agreed beforehand on what
entangled pair they want to get, so that Bob
immediately knows when Alice has measured on her end,
but again: this requires previous sublight
communication. No information is shared at measurement
time.
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> T-A
https://en.wikipedia.org/wiki/Hidden-variable_theory
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rramadass
Author: Prof. Douglas Ross of Southampton University -
https://www.southampton.ac.uk/~doug/
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noduerme
My question is, if I just refuse to believe in quantum
physics, that makes it go away and/or be inapplicable to
me, right?Uh oh, some people have no sense of humor =\
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atemerev
When I learned about causal sets program and algebraic
quantum field theory, I finally (somewhat) understood
quantum physics.Tl;dr spacetime does not exist as a global
background where things are "placed", it is not ontic.
"Things" are first, and spacetime is derived from
interaction statistics of "things". This eliminates nearly
all naive paradoxes like double slit etc. Now, these
"things" are somewhat complicated and non-intuitive (e.g.
there are no individual "particles", they are a limit of
discrete distributions), but that's a good start.
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> cgio
Sorkin is great. I think causal sets make some things
simpler but other more mysterious. I also found t'
Hooft's automata and Spekkens toy illuminating in
different ways.
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> > atemerev
"Was", unfortunately. He died this September. What
a loss, he earned a Nobel long ago.
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