The future of quantum biology and the applicability of quantum theory at high en

RubyWarbler

Where exactly the microscopic and macroscopic worlds do intersect? How big can the quantum realm be? Quantum biology attempts to answer these questions, proposing experiments or observations on living organisms that may be able to probe the limits of quantum theory. Such experiments or observations, some of which are discussed in this Essay, have already yielded intriguing but not yet conclusive results. Research moves toward macro-level experiments or observations. Thanks to quantum biology, quantum theory is forcefully appearing in the macroscopic world, to the point that we are close to an extension of the regime of validity of quantum theory that goes beyond the microscopic scale and includes all phenomena in which high energies are present. This idea, which could lead to an extraordinary paradigm shift, is endorsed by some recent results on the quantum physics of black holes.

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EmeraldBeetle

RubyWarbler

Thanks for this essay. If I understand you correctly, you are proposing that 'quantum corrections' should be thought of as governed by energy scale (e.g., horizon‑scale physics near black holes) rather than by length scale (as in microscopic quantum coherence). I’m not sure how you intend to bridge these very different regimes since your quantum biological examples are all low‑energy, microscopic and very strongly subject to environmental decoherence.

I'm also unsure about your use of 'entanglement' and 'macroscopic'. WRT the latter, the "microscopic and macroscopic worlds" are generally considered to "intersect" at what's called the 'mesoscopic' world, where quantum coherence and environmental decoherence compete leading to partially coherent and partially classical behaviour. For your examples of DNA proton tunnelling and photosynthetic energy transfer, you claim:

"Since it is an intramolecular transfer process, it therefore takes place on a larger, macroscopic, scale than “traditional” quantum mechanics, which focuses mainly on systems at the atomic and subatomic level.... Even in this case, the process takes place on a larger, macroscopic, scale than “traditional” quantum mechanics."

So, intramolecular doesn't mean macroscopic. AFAIU quantum biology, the relevant length and time scales here for both of these quantum effects are up to nanoscale and femto–picoseconds, thus all very firmly still within the microscopic realm or 'mesoscopic adjacent'. In contemporary usage, 'macroscopic' quantum effects refer to phase coherence over much larger scales usually at extremely low temperatures, such as for superconductivity for example. By contrast, the quantum effects discussed in quantum biology occur at nanometer scales, i.e., microscopic verging on mesoscopic and not anywhere near macroscopic. AFAIK there is currently no evidence for room‑temperature macroscopic quantum coherence in biological systems.

WRT entanglement you state:

"Entanglement is a quantum phenomenon in which two or more particles or energy states can become intrinsically correlated so that the state of one simultaneously influences the state of the other, regardless of the distance at which they are located. All this conflicts with Einstein’s theory of special relativity.... two “correlated” particles ... can communicate simultaneously thanks to entanglement"

This claim tends to conflate nonlocal correlations with communication. Entanglement does not enable faster‑than‑light signalling due to measurement outcomes on each side being locally random and the observed correlations (which can violate Bell inequalities) can't be used to transmit information without a classical \leq c channel. This is the 'no‑signalling theorem' and it is fully compatible with special relativity.

I think if you clarify these two points – on microscopic/macroscopic scale and entanglement/no-signalling – your overall argument will be more accurate and persuasive.

RubyWarbler

Thank you for reading my essay and for your comments. Regarding the points you raise:
1) The macroscopic/microscopic question is a question of terminology; here, by "macroscopic" I mean any scale larger than the atomic one.
2) "High energy" issue: "high" should not be considered in an absolute sense, but rather relative to the scale on which the phenomenon in question occurs. Obviously, defining the exact limits would require a situation-by-situation analysis, and there is still a lot of work to be done.
3) The entanglement issue: the definition concerns Einstein's initial idea that "horrible instantaneous action at a distance" would violate relativity. Various distinctions regarding the question of information transmission and the possibility of using entanglement for instantaneous communication came later.
Thanks again and best wishes.

EmeraldBeetle

RubyWarbler

Hi RW,

Thanks for the follow up, I do enjoy a dialogue! WRT:

" ... by 'macroscopic' I mean any scale larger than the atomic one"

1) I don't think that's a definition anyone else uses in any of the published science-based literature? So all you're doing is confusing people like me! There's no hard and fast definition but generally you'll find the nanoscale is where microscopic quantum effects grade into the mesoscopic grey area where environmental decoherence pushes you towards quasi‑classical mixtures. A 3 nm silicon chip process is definitely on that micro/mesoscopic edge while many mesoscopic phenomena apparently push the boundaries of coherence out to 100s of nm and beyond at low temperatures. Historically speaking, since the mid 1600s, if you need a microscope to see it then it's 'microscopic'. If you still insist on using your nonstandard definition then you should probably define it up front to avoid confusion, maybe something like 'macroscopic \equiv\,>atomic'.

2) On “high energy”, I'm happy for it to be contextual of course, but there's a gigantic gap between the energies relevant to quantum coherence in warm, wet biology and a black hole's horizon‑scale quantum structure with extremely high curvatures/energy densities. I'm not sure how you intend to 'unify' the energy scales between these two radically different regimes but calling them both 'high' is just semantics isn't it? I really have no idea what you're wanting to say here, so if you could unpack it I might be able to comment?

3) So yes, Einstein framed the debate in terms of 'spooky action at a distance' almost a century ago. And I personally think he saw the problem and strangeness of QM more clearly than most, along with Schrödinger. But in our modern 'no-signalling theorem' context there's no question that nonlocal correlations are real but that this doesn't violate SR. The standard model (as a relativistic QFT) respects this theorem, so no superluminal signalling.

Anyways, best wishes and thanks again for engaging!