
Study: Quantum biology – algae evolved to switch quantum coherence on and off - bkudria
http://www.science.unsw.edu.au/news/study-quantum-biology-algae-evolved-switch-quantum-coherence-and
======
stenl
"whether coherent quantum processes play a nontrivial role in biology" (from
the paper) is very controversial. The idea was that coherence would make
photosynthesis more efficient. If they're right about this mutation switching
between coherence and not-coherence, they should now proceed and test the
efficiency of the two photon harvesting modes.

~~~
stared
Quantum coherence is non-controversial, as it is the necessary condition for
binding atoms in a molecule (see
[https://johncarlosbaez.wordpress.com/2015/03/13/quantum-
supe...](https://johncarlosbaez.wordpress.com/2015/03/13/quantum-
superposition/)). What is controversial, is its spatial range in
photosynthesis.

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justifier
can anyone speak to the link between coherence and tree traversal?

the article and paper both seem to assume this connection should be known to
the reader while also suggesting this paper's discovered methods could answer
the relation, could someone bring me up to speed?

    
    
        “
        It was assumed the energy gets to the reaction centre
        in a random fashion, like a drunk staggering home.
        But quantum coherence would allow the energy to test
        every possible pathway simultaneously before
        travelling via the quickest route.
        ”
    

how complex are these routes? the paper cites that the team was able to use
'Crystallographic analyses [to] reveal two very different quaternary
structures' but i was unable to find any information on the complexity of
these structures

Traveling salesman problems can quickly become unwieldy so even if you allow
for the route traveled to be thought to be the quickest, testing this
hypothesis is equally intractable with current mathematics

from the paper:

    
    
        "from the insertion of a single amino acid, 
        the two αβ monomers are rotated by ∼73° to an 
        “open” configuration in contrast to the “closed”
        configuration of other cryptophyte PBP"
    
        "A central biological question is whether the
        presence of long-lived electronic coherence in the 
        light-harvesting proteins results in a selective 
        advantage for the algae—for example, is coherence 
        important for efficient light harvesting? If the 
        emergence of long-lived electronic coherence gives 
        cryptophytes containing the closed-form PBP a 
        selective advantage over the ancestral cyanobacteria 
        and red algae, it would seem that the Hemiselmis 
        cryptophytes, with their open-form PBPs, have lost 
        this advantage."
    

to summarise the paper would one say that the discovery of a new 'open'
configuration in a light harvesting algae has given us a mechanism to, in the
future, test the relevance of coherence to efficient routing?

~~~
stared
They are not that big. See my paper
[http://arxiv.org/abs/1310.6638](http://arxiv.org/abs/1310.6638) (especially
Fig 4).

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frozenport
What the heck is this article talking about!

Foremost, coherence is a property of tbe light and I dont see any queezing or
fock states so the quantum nature is not important. Does the absoption process
happen coherently with other protiens? Would this reduce the total amount of
light possible to absorb as it requires rejecting the incoherent photons?

What are these guys talking about?!

~~~
maxander
My (vague) understanding of the phenomenon being discussed is that it was
discovered that, in some of the proteins involved in photosynthesis, the
_electrons_ were passed around via multiple, quantum-entangled pathways. This
allows (supposedly!) better energy transmission than classical physics would.

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positron4
Wow! Thanks for the link. I never knew such a field even existed!

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wellyWellyWell

      But quantum coherence would allow the energy to test every 
      possible pathway simultaneously before traveling via the 
      quickest route.
    

Energy does not possess agency. A photon does not behave as Goldilocks anymore
than rain drops do.

If there's anything engaging in "decision making" if we must call it that,
it's the protein.

    
    
      In the weird world of quantum physics, a system that is 
      coherent can exist in many different states 
      simultaneously, an effect known as superposition.
    

Also silly.

The system does not exist in multiple states simultaneously. We just simply
lack the ability to know or measure the true state, so we invent a
hypothetical state to explain this on paper, and then proclaim victory for
ourselves.

~~~
jblow
I suggest you educate yourself about Bell's Inequality.

~~~
wellyWellyWell
Yes, yes, it's very cute to couch a belief in imaginary worm holes through
dimension X behind bland jargon like variable scoping.

And yes, just last month, incontrovertible evidence that with the knowledge of
a particle's spin at site A, I can instantaneously infer another particle's
spin at site B and always be correct. So magical.

[http://www.nature.com/nature/journal/v526/n7575/full/nature1...](http://www.nature.com/nature/journal/v526/n7575/full/nature15759.html)

But not because the particle landing at site B had already possessed a spin we
could not measure at the time of emission. No!

The spin was all things to all people when emitted, and would remain as such
until after we so courteously ask site A's particle to reveal its spin!

Bell says that the spin instantaneously traveled through a worm hole, _across
space and time,_ whispering in the ear of the site B particle, so that it
could poof! Change it's mind!

Bell says no unknowable secrets allowed.

Bell says everyone can have everything.

Bell says it's not because of something we can't determine.

Bell says it's because of a special message transmitted in a way no one can
intercept. Not even him!

Bell says we must have our love notes dictated to us after they are sent, and
only then may true love be known! Until then, the notes are written in all
languages, as both hate and love, war and peace!

Bell says Bob won't love Alice until Alice loves Bob! That Bob's note re-
writes itself before his love can be unrequited because Bob refuses to get
dumped!

~~~
wellyWellyWell
To sum up, with less snark, because I'm not directing the snark at you... It's
directed at Bell, as posthumous snark, since I'm sure he won't feel it.

Anyway, I don't ascribe to the school of thought that tells us that simply
because superposition works on paper, that such a predictive tool accurately
reflects events occurring in reality.

It may help us, to understand and _deal with_ curious events, but Bell hasn't
accomplished anything profound in making his pronouncements.

All he did was insist that people shift conceptual placeholders about, to help
reorganize a mental model for imagining representations of an idea. To regard
his hand-wavy declarations as a crystallized description of reality is
nonsense.

Ask this: If something cannot be touched, known or inferred, then how can he
assert that reality reshapes itself in reverse upon reaching an event, or that
an untouchable relationship persists behind the facade or our reality?

Furthermore, his arguments are pure semantics. One is not allowed to presume
independent unrelated _inaccessible_ slots, one must assume _related
inaccessible_ slots. Even though the relationship of the slots is not actually
revealed until after it no longer matters whether there was a relationship or
not. Oh, and by the way, that relationship transcends reality as we know it,
possibly implying a parallel channel of communication, external to our world.

Sure, so much better than just stating that there is information missing from
our representational model at certain moments in the sequence of events.

~~~
justifier
i am always confused when bell comes up and people use it as an argument for
'the probabilistic nature of quantum mechanics'

as i stated in my comment defending your original skepticism: 'i find that
science as a verb often is the act of discovering previous understandings were
inadequate to describe phenomena'

bell's inequality was a direct response to the Einstein-Podolsky-Rosen paradox
which wanted to assert philosophically the inadequacy of quantum mechanics

conversely bell shows empirically the inadequacy of classical mechanics

which seems uncontroversial.. how many times historically have we shown
contemporary classical mechanics to be wanting?

bell, to me, simply says if you wish to find relation between bodies
associated with classical mechanics and bodies associated with quantum
mechanics you are going to have to do better, and i'd argue.. on both fronts

