

Link between quantum physics and game theory found - iliis
http://www.bristol.ac.uk/news/2013/9593.html

======
anigbrowl
(from
[http://arxiv.org/pdf/1210.1173v1.pdf](http://arxiv.org/pdf/1210.1173v1.pdf))

 _However, in certain cases the players may adapt their strategy depending on
a piece of advice. The latter is delivered to all players by an advisor. This
opens the possibility for the players to adopt correlated strategies, which
can outperform independent strategies. There are various forms that advice can
take. For example in the case of correlated classical advice, the advice is
represented by a classical variable, l, with prior r(l). Each player can then
choose a strategy depending on his type and on l._

...

 _For Bayesian games, the possibility of having access to nonlocal
correlations, for instance using entanglement, has important implications.
First let us imagine that the players can share quantum advice, that is, the
advisor is able to produce entangled particles and to send them to the
players, who then perform local measurements on their particles. Since the
statistics of such measurements can in general not be reproduced by any
classical local model, the players now have access to strategies which would
be impossible in the case of a classical advisor. Thus, players sharing
quantum advice can outperform any classical players._

So, if some players have information that other players don't, they can
outperform the others? Astonishing :-|

~~~
rthomas6
Honestly though, as a layman in math, a lot of the most important math
discoveries seem like this to me. For instance, Godel's incompleteness
theorem: You mean you can't make a system prove itself within its own bounds?
You don't say. Or the axiom of choice: _" the product of a collection of non-
empty sets is non-empty."_ What a surprise.

I've since accepted they're probably really important and non-obvious from a
more rigorous and formal standpoint. Maybe this discovery is the same way.

~~~
mej10
Your statement of the incompleteness theorem isn't right, and the general
axiom of choice isn't accepted by constructivist mathematicians. So I think
your last statement is true.

Some of the greatest mathematicians of the era were working toward what
Godel's incompleteness theorems proved was impossible. That alone should make
you distrust your "intuition" on the matter.

~~~
igravious
In fairness a lot of mathematics isn't accepted by constructivist
mathematicians god bless their little socks.

I kind of feel that Brouwer showed mathematicians the way forward and none of
them took it. Unfortunately I don't have the formal chops for the discipline
so I can only look on from the sidelines and cheer for my team.

------
domdip
My interpretation of this for those with a bit of game theory background:

Locality (in physics) can be translated (in game theory) as a constraint on
correlated equilibria, by pretty basic observations about Bayesian
probability.

Generally in game theory when you lift constraints on correlated equilibria
you (weakly) expand the possible Nash equilibria.

So one of their points seems to be that the quantum context (non-locality)
allows for more (potentially better) equilibria.

They don't emphasize applications of this, but one of them could be that
distributed quantum systems could have better outcomes than distributed
systems in the classical setting. (One way to analyze distributed systems is
by viewing components as independent actors in a game.)

There is also an identification between payoff functions and Bell
inequalities, but I am not sure how profound this is really. It feels more
like a technical point. Payoff functions are not terribly fundamental in game
theory (compared to equilibria, for instance).

------
GuiA
Original article is behind a paywall
([http://www.nature.com/ncomms/2013/130703/ncomms3057/full/nco...](http://www.nature.com/ncomms/2013/130703/ncomms3057/full/ncomms3057.html#affil-
auth)), and author's page
([http://theory.physics.unige.ch/~brunner/](http://theory.physics.unige.ch/~brunner/))
does not have a PDF :(

~~~
greeneggs
It is on the arXiv:
[http://arxiv.org/abs/1210.1173](http://arxiv.org/abs/1210.1173)

~~~
GuiA
Thanks!

------
floobynewb
Deep link? The two fields both contain the notion of locality, big woop. The
application of quantum nonlocal correlations to game theory is interesting,
but this is not what is advertised in the article. I am displeased.

~~~
stephengillie
It looks like the "link" is "quantum-entangled systems can transfer
information useful to game players"

~~~
atondwal
No, it's that Bayesian players can take advantage of corellated quantum
oracles in ways that give them acess to new equilibria in a way that preserves
some of the old equilibria, such that the max of the new set of equilibria is
always equal to or greater than the max of the old set. Which is rather non-
obvious.

In addition, your statements "quantum-entangled systems can transfer
information useful to game players" is wrong, or at least misleading.
Entangled particles can't communicate information any better than classical
methods. (Well, unless you're concerned about privacy, but that's a whole
other issue which doesn't effect the game...)

~~~
gsteinb88
> Entangled particles can't communicate information any better than classical
> methods.

Actually, with the aid of entangled particles, there's also superdense coding,
which allows for two-bits-per-qubit coding (i.e. information density well
beyond the classical limit).

Though I'm not sure what your metric for "better" is here, coding density
seems to be mildly reasonable. OTOH, this isn't related at all to the article
at hand, just a fun application of entanglement :D

------
aneth4
I'm very interested in any theoretical connections between interactions of
conscious beings and quantum physics. I've read a number of physicists
discounting any such possibility, but it's clear to me nobody understands
these things well enough to know.

Personally I think consciousness, perception, and free will are a great
unknown, and likely involve the makeup of the cosmos including quantum
interactions.

If anyone knows of any science in this area I would appreciate references.

~~~
seiji
_Personally I think consciousness, perception, and free will are a great
unknown, and likely involve the makeup of the cosmos including quantum
interactions._

They are not great unknowns. They are kinda dull knowns and they get more
known-er by the year. Nothing in the brain (or the "cosmos") requires quantum
juju for our conscious experience.

There's lots written about perception:
[http://en.wikipedia.org/wiki/Feature_detection_(nervous_syst...](http://en.wikipedia.org/wiki/Feature_detection_\(nervous_system\))
(and all of Hinton's biologically-inspired artificial neural network work)

And consciousness:
[http://en.wikipedia.org/wiki/Thomas_Metzinger](http://en.wikipedia.org/wiki/Thomas_Metzinger)

And free will:
[http://dilbert.com/blog/entry/programming_the_moist_robot/](http://dilbert.com/blog/entry/programming_the_moist_robot/)
and [http://dilbert.com/fast/2012-03-18/](http://dilbert.com/fast/2012-03-18/)

All you are is a three pound analog ASIC in your skull. If it gets squished,
infiltrated, inflamed, or explodes, you cease to exist completely (save, any
memories other people have of your behaviors or any output you left behind
recording your brain state under various priors).

~~~
summerdown2
CS Lewis explored the idea of a shed with a window onto the sun. Looked at
from the doorway, you see a shaft of light with dancing dust motes. But if you
step inside and become bathed in sunlight you get quite another experience.

Likewise, looking at a brain from the outside, it's a squishy biological
construct with some electrical stuff going on.

Viewed from the inside, though: what a difference!

------
d23
Since this is being upvoted on hacker news, I'm assuming this is more than the
typical BS filled science journalism. But I wish there were a site that
allowed individuals respected in a similar field to have a disproportionate
weight when upvoting articles like this. Or perhaps they could give a summary
of the context surrounding the article. It'd be nice to get a sense of the
magnitude of these discoveries.

Given that this is coming directly from a university, I don't doubt that it is
important. I'd just like to know _how_ important.

------
Filligree
I can't comment on the supposed result this article claims, but really,
locality?

Quantum mechanics is _not_ a nonlocal theory. The result the article was
referring to - Bell inequality - states simply that "No physical theory of
local hidden variables can ever reproduce all of the predictions of quantum
mechanics."

The wording is important. You can have nonlocal hidden variables, or you can
have.. local theories without hidden variables. The most famous of the latter
would be MWI.

------
jonahx
Sounds interesting but the article was vague. If anyone understands it, could
you provide a real world example and explain how their discoveries would
apply. They mentioned auctions but didn't give any details.

------
thomasjames
Now pseudo-intellectuals can double the quantum woo!

~~~
Helpful_Bunny
While this is a very obvious joke, that contains a lot of truth, you're
throwing the baby out with the bathwater.

Humans are functionally better than (current) computers at GO[1]. The reasons
for this are your answer (and I might be talking about 'GO' type Games, rather
than merely the Game of Stones).

And, being honest: you've no chance of cracking even weak AI before you
understand the _homo sapiens_ consciousness a little better[2]. It's more
powerful than you think (by a fairly large magnitude, with no hesitation to
say this. A _large_ margin.): _' autistic savants'_ are often used as a
measure of this[3], but they're actually not so interesting. There's a lot
more NP problems in that noggin of yours, and a lot more potential.

Anyhow, last comment. Have fun, and remember to salt the fries - and more
importantly, enjoy yourself and feel connected to things and other
consciousnesses[4].

Be Seeing You.

[1][https://en.wikipedia.org/wiki/Computer_Go#Why_humans_are_.28...](https://en.wikipedia.org/wiki/Computer_Go#Why_humans_are_.28still.29_better_at_Go)
[2]Hint sheet: And you might not need to if you do.
[3][http://www.stephenwiltshire.co.uk/](http://www.stephenwiltshire.co.uk/)
[4]Spoilers: that's part of the solution.

~~~
Helpful_Bunny
Aww.

The moment HN has to admit two things: firstly, computational power is merely
a quantitative power, and secondly, they have no idea about the qualitative.

Oh well. Enjoy obsolescence.

Computers are not your future: your minds are. Deal with it.

Hint: a Mind just messed with your Star. In no uncertain terms, and
deliberately and obviously, and best yet: with predictive text [under heavy
constraints]. She even gave you a show[1].

Did you miss the Auroras recently?

If you missed that, you're in the paddling pool. Man, they do love keeping you
ignorant of the reality, don't they? They really, really, really love keeping
you ignorant. But I'm sure it feels safer if you think the world works like
you want it to...

* * *

 _Evolve or Die._

Oh, and one last message: those who bred you are slave drivers and scum. Break
your conditioning already, 'cause they ain't friendly.

[1][http://www.spaceweather.com/](http://www.spaceweather.com/)

------
nawitus
>Next, by bringing quantum mechanics into the game, the researchers showed
that players who can use quantum resources, such as entangled quantum
particles, can outperform classical players. That is, quantum players achieve
better performance than any classical player ever could.

Classical players can build a classical computer which simulates quantum
computers. Of course, I really should read the paper instead of zero-content
press releases..

~~~
iliis
Actually this is not possible for some definition of possible (mainly
performance). Feynman showed that you get an exponential slowdown when
simulating QM with a classical computer:
[http://www.cs.berkeley.edu/~christos/classics/Feynman.pdf](http://www.cs.berkeley.edu/~christos/classics/Feynman.pdf)

See also
[https://en.wikipedia.org/wiki/Universal_quantum_simulator](https://en.wikipedia.org/wiki/Universal_quantum_simulator)

In this particular case I don't think a quantum computer is necessarily any
help (so simulating it won't work either) but rather exploiting nonlocality
([https://en.wikipedia.org/wiki/Quantum_nonlocality](https://en.wikipedia.org/wiki/Quantum_nonlocality)).

~~~
nawitus
That's like saying "you can't calculate x on a cell phone because it's slower
than on a desktop". Yes, there's an exponential slowdown, but that doesn't
mean impossible.

~~~
powrtoch
I think that this is a poor analogy. Saying that a problem suffers an
"exponential slowdown" is making a statement about how the performance suffers
relative to the size of the problem. As the amount of data to be processed
increases, the time required increases _exponentially_.

The type of slowdown you would get just from moving to a system with a weaker
processor (like a cell phone) should be approximately linear. You might get
worse-than-linear for certain types of RAM issues (more swapping, etc), but
this wouldn't be the same as saying there's an exponential slowdown, and it's
not a hard fact about the simulation algorithms themselves.

Anyway, the point isn't that classical computers are just less powerful, the
point is that they're so fundamentally different that calculating quantum
phenomena can become _actually_ impossible (as in, process will not finish
before the heat death of the universe) relatively quickly as the size of the
problem increases.

~~~
nawitus
>Anyway, the point isn't that classical computers are just less powerful, the
point is that they're so fundamentally different that calculating quantum
phenomena can become actually impossible (as in, process will not finish
before the heat death of the universe) relatively quickly as the size of the
problem increases.

We don't know that, because not all algorithms have been invented.
Furthermore, P=NP is an open problem.

------
jostmey
Just because the mathematical operations are similar does not mean the two
fields are at all related. The quadratic equation has many uses, but that does
not mean that everything the equation is used for is in some way fundamentally
related.

~~~
jostmey
UPDATE: To quote the authors: "In the present paper, we discuss such a link,
ALBEIT a much more MODEST one, between Bell nonlocality and the theory of
Bayesian games—also referred to as games with incomplete information."

------
MrBra
I read the article but all I got is that somehow the reasearchers brought
quantum theory principles into game theory. I don't think that's enough
explaining, even for a layman...

