
Purifying Physics: The quest to explain why the “quantum” exists - aethertap
https://plus.maths.org/content/purifying-physics-quest-explain-why-quantum-exists
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stared
Please... what is "embarrassing" about quantum mechanics? (As an (ex) quantum
physicist I consider the desire to "metaphysically understand" anything a
mental trap.)

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jerf
This sounds less like metaphysics and more like a math exercise to me, though.
Deriving a smaller handful of cleaner axioms that result in quantum mechanics
is a valid exercise in mathematical cleanup. And if I'm reading their claims
correctly, doing so such that all but one axiom equally applies to classical
mechanics, and only the introduction of one specific one yields quantum
mechanics, would be legitimately interesting mathematically. It reminds me of
Euclid's Fifth axiom, where it turns out that tweaking that one specifically
yields multiple different valid geometries.

It probably isn't really progress in the sense the article writer thinks;
juggling isomorphic representations is in some sense not "really" progress.
But it can still be worth it for the practical improvements and potential
didactic improvements. Perhaps if we had better education for QM with a better
mathematical model, it would lead to less existential angst in the first
place. I've seen Scott Aaronson trying to do some work on that front as well.
In fact I'd consider it ironic if QM turns out merely to be slightly difficult
and a hundred years of psuedo-philosophical babbling sourced from nothing more
than a slanted view of relatively simple principles. I think some people will
actually get _upset_ if there is success in taking the mysticism away from
QM....

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Zuider
They say that the Born rule can be derived from first principles from their
set of axioms. In other formulations, it must be assumed without further
explanation. That is progress.

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stared
It has already 10 years, at least: [http://arxiv.org/pdf/quant-
ph/0405161.pdf](http://arxiv.org/pdf/quant-ph/0405161.pdf) (a great paper
IMHO)

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pjdorrell
From my limited understanding of QM, it would appear that their assertion,
that all "mixed" states are really part of a "pure" state, is just a
restatement of the Many Worlds hypothesis. In the MW hypothesis, reality is
described by the wavefunction of the whole universe, which is a single "pure"
vector in Hilbert space whose operators are observables on the whole universe.

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fengwick3
Paper on the 5 axioms: [http://physics.aps.org/featured-article-
pdf/10.1103/PhysRevA...](http://physics.aps.org/featured-article-
pdf/10.1103/PhysRevA.84.012311)

It looks familiar actually; it could be posted on HN or had generated an
initial pop science hype wave when it was first published.

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musgravepeter
Thanks for the link. That is a pretty long paper!

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dschiptsov
After couple of thousands of years LHC would be viewed the same way we
consider Egyptian Pyramids today.

Back then Egyptians were sure that everything they do makes a perfect sense -
the height and shape of structures are in accordance with the opinion of the
most knowledgable and authoritative experts, writings on the walls are
perfectly correct and verified many times, etc.

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bitwize
I think the LHC would rather be recognized as the precursor to the tabletop
hadron colliders that smart kids get as birthday presents.

Beaides which, the pyramids _are_ pretty remarkable from a scientific and
mathematical standpoint.

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dschiptsov
The point was about a set of current beliefs which determined the direction
which big social events would take. GHC project, like pyramids, is a way to
get living for so many people and organizations in the first place.

There is still no consensus among philosophers and, of course, no empirical
evidence of existence of time as a phenomena of the Universe, apart from
mental concept which could be derived from this or that physical processes
using mathematical modeling. But for math models being proven does not imply
existence. There are phenomena we call "mass", and hence phenomena we call
forces, there is notion of distance, succession, rate of change, but there is
no phenomena of time apart from some physical process observable by a mind.
The famous clocks being accelerated is mere a mental construct.

How come that we are so convinced that time exist? Well, suppose you have
arrived to some big Tibetan Monastery in Lhasa or Shigatse at the beginning of
the last century. You will be overwhelmed by the architecture, paintings,
buzzing activities, which all seemingly makes perfect sense for those who
performs them. All the rituals, offerings, recitation of scriptures, daily
duties, strict hierarchy, etc. Much like MIT nowadays.)

Unless you are questioning everything, trying to reduce everything back to
first principles, being skeptical and aware of socially constructed dogmas,
you will be convinced very quickly that there are various buddhas and other
deities which appear and disappear upon their will, that they hide some
scriptures in the past, to be revealed when humanity will be ready for the
knowledge. You will study cosmology, reasoning, philosophy of emptiness, as a
refinement of crude ancient Indian philosophy (which is the only real marvel
Tibetan culture produced) and so on. If you are good student you will become
very good rimpoche, expert in all the subtle details of the teachings. I am
seasonal guide in Tibet, so I know what I am talking about.)

What do we call notions held firmly by society but which cannot be empirically
proven? We call it beliefs. How do we call organized beliefs, supported by
social institutions? We call it a religion. Modern quantum physics is nothing
but a bunch of religious sects.

BTW, traditional Indian philosophy, which goes back to Upanishads, put the
human mind in the center, so it could observe itself, how easily and readily
it produces chimeras and dogmas. The two almost unbreakable of these is
"myself" and "time". Upanishads were the very first systematic discourses
which attempted to prove logically non-existence of these mental concepts.
Still, no one managed to refute Upanishads. "A priori" established by Kant is
related to that mind - an observer, not to the observed Universe.

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AnimalMuppet
> There are phenomena we call "mass", and hence phenomena we call forces,
> there is notion of distance, succession, rate of change, but there is no
> phenomena of time apart from some physical process observable by a mind. The
> famous clocks being accelerated is mere a mental construct.

Well, you list "rate of change" among your phenomena, but deny time as part of
the phenomena. But how can rate of change be a "real" phenomena without time
also being "real" in the same sense? "Rate of change" is really "rate of
change with respect to time", after all.

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dschiptsov
There are slow rivers and quick ones. Even same river has spots with different
rates of flow. But there is still no time.)

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sandworm101
>>Quantum mechanics ... allows us to describe elementary particles and
fundamental forces, to understand chemical reactions, and to construct lasers,
transistors, and computers.

What? So much for purifying the discussion. I know a little about the history
of electronics and do not remember any discussion of quantum mechanics by
those building the first computers, lasers or transistors. These were rather
practical inventions based on easily observable experimentation.

The field of quantum physics certainly allows us to better understand how and
why these devices work, and to improve them, but it is not responsible for
their existence.

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swehner
One explains semiconductors using quantum mechanics.

Computers are constructed with semiconductors.

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sandworm101
That was my point. The OP states that quantum mechanics "allows us to
construct", not only describe.

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typon
Incorrect. Lets say I grant you that Shockley and Bardeen didn't know anything
about quantum mechanics and constructed the first transistor purely due to
"observable experimentation" (whatever that means), that idea is completely
false today.

I use and write atomistic simulators and semi-classical (finite-element
analysis based) simulators to simulate modern FET devices every day as part of
my research. I literally use quantum mechanics to write the algorithms behind
the simulator (DFT, NEGF in my case). Moreover, if you look at the manual for
Synopsys Sentaurus (which is the semi-classical simulator), they have hundreds
of pages describing the derivation of their mobility models and structural
models from basic quantum theory.

In summary, modern transistors are most definitely constructed taking quantum
mechanics into account because without it you wouldn't have transistors
functioning at 90nm much less at 14nm. You wouldn't take into account gate-
leakage, tunneling, stress, bandstructures, and a host of other properties of
modern transistors.

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sandworm101
Read the early experiments with crystals (not wikipedia, which most deals with
stuff post-patent). They didn't start with physics textbooks. They started
with odd electrical behavior observed in practical experiments.

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typon
I already granted you that.

