Scientists have a history of trying — and failing — to link biology and quantum mechanics. The real connection between them may be in the math.

123 points•pseudolus•6 days ago•60 comments•

60 comments

__MatrixMan__4 days ago
I feel like "is biology quantum?" gates are kept in a needlessly stringent way.

They say that biological systems are too warm for quantum coherence to persist long enough to have meaningful effects. But if you have some molecule whose conformation is in a superposition of states--however briefly--and then the environment causes it to decohere and take on some fully determined non-quantum shape... that actual shape is still one of many possible ones into which it did not decohere. The environment has still hacked probability to trigger decoherence into this shape and not some other one, and evolution leans on this.

If you took a classical bag and filled it with classical locks and classical keys and just shook it around for a while, none of those keys would end up in the locks. But because of this quantum lubricant, ligands binding receptors do find themselves in the appropriate conformation to facilitate signal transduction, even at low concentrations. It's absolutely astounding that it works at all, and in a fully classical world it wouldn't for the same reason that the keys don't end up in the locks when you shake the bag for a while.

Biology is plenty quantum, and the people who are here to tell you it isn't are citing the abundance of interactions as evidence that it is not quantum, but it's through those many interactions that its quantum nature expresses itself.

Maybe it's not spooky-action-at-a-distance style quantum. Maybe it's not indeterminate enough for this theoretical purpose or that one. If you're trying to cram god in there, well it might not be quite spooky enough for that, but so much of what happens in the macroscopic world would not happen if the quantum world were not as strange as it is, and that's doubly true for biology.

FeepingCreature4 days ago
Aiui most people who push for "biology is quantum" specifically want the large-scope effects because they're grasping for it as a way to justify why consciousness is special. Cells are of course plenty quantum at the scale of molecular interactions.
aeonik4 days ago
I think you are right, but this is a straw man.

There are some quantum consciousness cults out there, but plenty of people are interested in investigating the quantum nature of biological effects including consciousness that aren't quacks.

There is also a tendency for some scientists to react dismissively to hypotheses associated with pseudoscience, even when the narrower scientific question is perfectly legitimate.

Reminds me of the visceral reactions in history, like the Rejection of Continental drift (i.e. high level idea was right, but mechanisms hadn't been pinned down yet).

Not claiming that the quantum hypothesis is right, just saying we didn't jump to conclusions.

jryb4 days ago
Your key and lock analogy is simply incorrect. Those interactions can be modeled with classic electrochemistry and are super predictive - the specificity is driven by evolution, not quantum mechanics. I mean sure, every system is technically quantum mechanical but those effects are never explored afaik.

There are even educational demonstrations where people shake bags of 3D printed proteins with magnets (including competing proteins) and you end up with the expected structure.

timschmidt3 days ago
> every system is technically quantum mechanical but those effects are never explored afaik

Photosynthesis depends on quantum behavior: https://www.youtube.com/watch?v=rvFMBRnR3ms

__MatrixMan__4 days ago
classic electrochemistry has plenty of quantum effects baked into the parameters of the theory, it just doesn't bother to explain them in quantum terms.

I'll have to look up those demonstrations. I know if I were making such a thing I'd stack the deck in favor of a good demonstration and I'd stick to very simple interactions. But if they've given the potential for random useless tangles a fair shake I'll have to rethink my position.

If somebody has made some analog of ATP synthase which operates in this way it would be just fantastic to behold.

Although if I did relax this position, I'd then be in need an explanation for why all of biochemistry feels like it takes place in some kind of cartoon universe. Like, maybe I've failed to put my finger on the reason, but I can't shake the feeling that the world being presented in biology class is just a little too cute to be this one.

Eridanus24 days ago
The keys could random walk to lock-ports in finite time iff the search space were 2D or 1D. In 3D space, it is gets very unlikely. Biology solves it by dimensionality reduction, find substrates, cling, slide and find love/compatible hole.
HarHarVeryFunny3 days ago
The article acknowledges that quantum behavior like tunneling necessarily happens everywhere, if you look at the relevant scale, and also seems very clear about what it is actually talking about - whether classical-scale quantum effects can be seen in biology.

You seem to talking at cross-purposes to the article - not arguing against the research it is discussing of classical explanations of quantum-like behavior, but wanting to point out that biology is not immune to quantum effects at the scale where that is not surprising.

__MatrixMan__3 days ago
You're right on both points. The article isn't misleading, I just think it's an entry into a space which has overreacted to quantum woo woo in an unhelpful way.
joebig4 days ago
There is some inaccuracy here I think. Decoherence means washing out of interference phenomenon, viz. you will observe no fringes in the double slit experiment with incoherent source pair (they switch so rapidly as to end up plain grey). What is erased or overwritten in tiny timescales cannot have a residual resultant or guiding gulley effect, or as you say, freezing the pattern/steric landscape in a preffered state repeatably. It would be tantamount to observing the fringe pattern with incoherent sources, for all timescales.
__MatrixMan__4 days ago
Take flash memory for example. We read the bit via quantum tunneling. We don't have to wait for the electron to actually bounce out of its little box, we can detect the small probability that it might, and then we can act on that detection.

So every time I act on the basis of such a read event, am I not being guided down one of gulleys that were set up by the designer of my device (or, analogously for biology, by evolution)?

smashers11144 days ago
I feel like the author was either trying to write to a pretty lay audience or didn't understand the broad applicability of quantum mechanics. There is no threshold either where things are "classical" or "quantum". The systems that may be satisfactorily described by classical mechanics are just those in which the Planck constant may have a value of zero. While in modeling a system using quantum mechanics, it has a finite value.

Computational chemistry is based on different approximation methods for evaluating the interactions of a molecule with another. These methods work well, and as you can imagine form a large portion of biochemistry. Saying "Biology may not be quantum.." in the title seems pretty misleading at best.

Most of the interview quotes are researchers talking about any sort of long term coherence used in a biological organism. The article mentions this in brief but I didn't see a link. For a real cool example of biology pushing quantum limits check out the magnetic field "vision" of birds [0].

[0] https://www.pnas.org/doi/10.1073/pnas.0711968106

dataviz10004 days ago
Something similar came up in Neil deGrasse Tyson's StarTalk yesterday. [0]

Neil deGrasse Tyson used the number 8 as an analogy to explain that mathematical similarities between two systems do not mean they share a physical connection -- they were discussing how both the universe and human brain can be described using fractal mathematics. He pointed out that you can count 8 planets in the solar system and 8 children in a room, but having the same count doesn't mean the children are planets.

The similarities say more about mathematics than it does about the universe and the human brain or planets and children.

[0] https://www.youtube.com/watch?v=0zNnJ2AzmA4

melvinroest4 days ago
That it says something about the human brain seems to be about right. If you have 8 planets and 8 children it means you've classified certain things you've seen to be part of the same concept and you group them together.
chasil4 days ago
Bilology is quantum? It is the bottom of the food chain.

https://www.kavlifoundation.org/news/unraveling-the-quantum-...

Edit: FTA, "In photosynthesis, for example, organisms use specialized pigments and proteins to harvest light with nearly perfect quantum efficiency; they convert almost every incoming photon into useful chemical energy."

Edit: this is about standing waves and overtones: "In 2024, Scholes found a way to design complex networks of oscillators such that they produced emergent states — stable patterns of synchronized behavior, like a crowd that claps in time — that could be mathematically described as vectors in a Hilbert space."

Read the full thread on Hacker News →

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