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Quantum weirdness is everywhere in life

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Re: Quantum weirdness is everywhere in life

#61

Post by _rpd »

dekhn wrote: post #44
titzer wrote: post #4

"The colour of your eyes, the shape of your nose, your intelligence or propensity for disease are encoded at the quantum level." Uh, nope.

I'm a biophysicist. Almost most of my work uses entirely classical approximations to quantum (which themselves are parameterized using quantum chemistry and physics), I can assure you, that by definition, all biology is inherently quantum. The physics of hydrogen bonds practically guarantee it (to the extent we can make positive factual statements). The biophysics of DNA mutation repair -- DNA mutations are a major c…

But isn't the reason that the classical approximations work so well that quantum effects are drowned out by the thermal noise floor at room temperature? And reliable processes like DNA replication have to depend on 'classical' chemical bond energies that are at least a couple of orders of magnitude above the noise floor, right?

Re: Quantum weirdness is everywhere in life

#62

Post by dekhn »

_rpd wrote: post #61
dekhn wrote: post #44

Earlier quoted context omitted.

I'm a biophysicist. Almost most of my work uses entirely classical approximations to quantum (which themselves are parameterized using quantum chemistry and physics), I can assure you, that by definition, all biology is inherently quantum. The physics of hydrogen bonds practically guarantee it (to the extent we can make positive factual statements). The biophysics of DNA mutation repair -- DNA mutations are a major c…

But isn't the reason that the classical approximations work so well that quantum effects are drowned out by the thermal noise floor at room temperature? And reliable processes like DNA replication have to depend on 'classical' chemical bond energies that are at least a couple of orders of magnitude above the noise floor, right?

No. I think part of the reason people are having so much trouble on this thread is they are confusing the field of quantum physics with quantum chemistry.

The processes of DNA replication actually involve hydrogen bonds, and comparing the relative energies of different forms of hydrogen bond groups, at or near the thermal limit (1-2 kcal/mol).

Re: Quantum weirdness is everywhere in life

#63

Post by Florin_Andrei »

TTPrograms wrote: post #50
rogerbraun wrote: post #17

It's always a shame when the Copenhagen interpretation of quantum mechanics is presented as how reality works. Most of the perceived weirdness of QM comes from the leaps of faith required to make the Copenhagen interpretation work.

Quantum mechanics is simply a set of equations that describe the universe. Whether or not those equations make sense or are interpretable is irrelevant, as our capability to understand intuitively is only based on the types of interactions we observe every day. To ask somebody what interpretation they prefer is akin to asking a mathematician how they interpret the reality of ZFC they prefer. It's interesting, but ult…

> To that end, Copenhagen makes the important point - "Shut up and calculate".

No, it doesn't. It adds a few assumptions on top of that. That's the point of the whole debate. To be fair, the many-worlds interpretation also does that.

Re: Quantum weirdness is everywhere in life

#64

Post by Florin_Andrei »

dekhn wrote: post #44
titzer wrote: post #4

"The colour of your eyes, the shape of your nose, your intelligence or propensity for disease are encoded at the quantum level." Uh, nope.

I'm a biophysicist. Almost most of my work uses entirely classical approximations to quantum (which themselves are parameterized using quantum chemistry and physics), I can assure you, that by definition, all biology is inherently quantum. The physics of hydrogen bonds practically guarantee it (to the extent we can make positive factual statements). The biophysics of DNA mutation repair -- DNA mutations are a major c…

> that by definition, all biology is inherently quantum

All chemistry is quantum already.

Re: Quantum weirdness is everywhere in life

#65

Post by TTPrograms »

Florin_Andrei wrote: post #63
TTPrograms wrote: post #50

Earlier quoted context omitted.

Quantum mechanics is simply a set of equations that describe the universe. Whether or not those equations make sense or are interpretable is irrelevant, as our capability to understand intuitively is only based on the types of interactions we observe every day. To ask somebody what interpretation they prefer is akin to asking a mathematician how they interpret the reality of ZFC they prefer. It's interesting, but ult…

> To that end, Copenhagen makes the important point - "Shut up and calculate". No, it doesn't. It adds a few assumptions on top of that. That's the point of the whole debate. To be fair, the many-worlds interpretation also does that.

What testable assumptions does Copenhagen add to quantum mechanics? Are there other interpretations that don't add testable assumptions?

Re: Quantum weirdness is everywhere in life

#66

Post by n4r9 »

williamjennings wrote: post #39
n4r9 wrote: post #32

Earlier quoted context omitted.

I meant "rigorous and comprehensive" to include "representative of the entire quantum community". That poll was conducted at a single conference and had 33 participants. The bias inherent in this approach can be seen when the same poll was conducted at two other conferences: http://arxiv.org/abs/1303.2719 http://arxiv.org/abs/1306.4646 In both cases, de-Broglie Bohm interpretations ruled the day. As the abstract of t…

My opinion is that the Copenhagen interpretation does not contradict DeBroglie in terms of nuclear chemistry, but solely thermodynamics. The Copenhagen interpretation makes a leap of faith with the Born Rule as it is based on Maxwell-Boltzmann statistics. The work of t'Hooft is a more modern alternative for ensembles where the outcome is stochastic, rather than probabilistic. Photosynthesis has that property, as do m…

Not sure what you mean by "contradict". Certainly you won't easily find experiments for which the two offer different predictions. They are very different in terms of their ontology though: DeBroglie states that particles have definite positions and momenta at all times whereas Copenhagen does not.

Re: Quantum weirdness is everywhere in life

#67

Post by wpietri »

kordless wrote: post #52
titzer wrote: post #43

Earlier quoted context omitted.

Reading their abstract makes me cringe. "The principle that mutations occur randomly with respect to the direction of evolutionary change has been challenged by the phenomenon of adaptive mutations. There is currently no entirely satisfactory theory to account for how a cell can selectively mutate certain genes in response to environmental signals. However, spontaneous mutations are initiated by quantum events such a…

You say it makes you 'cringe', yet you offer no substantial argument to why you are fearful of their hypothesis. Saying things like "BS" and "WTF" is a weak attempt at hacking biases, and usually attributed to dissonance. I don't accept biased arguments as truths. Quite the contrary, I see them as indicators of an unresolved argument. I'm not afraid of their hypothesis and I welcome the truth, however weird it may be…

I didn't read that as fear of their hypothesis. I read it as irritation with the enormous amount of quantum waffle offered by loons, quacks, and frauds. Evolutionary biology has also had to deal with pseudoscientific intrusion from the get-go.

This paper may be totally legit, and quantum magic may really be how biology works. But I can totally see why someone would whip out Occam's Razor and start slashing after reading that paragraph.

Re: Quantum weirdness is everywhere in life

#68

Post by omalleyt »

TTPrograms wrote: post #50
rogerbraun wrote: post #17

It's always a shame when the Copenhagen interpretation of quantum mechanics is presented as how reality works. Most of the perceived weirdness of QM comes from the leaps of faith required to make the Copenhagen interpretation work.

Quantum mechanics is simply a set of equations that describe the universe. Whether or not those equations make sense or are interpretable is irrelevant, as our capability to understand intuitively is only based on the types of interactions we observe every day. To ask somebody what interpretation they prefer is akin to asking a mathematician how they interpret the reality of ZFC they prefer. It's interesting, but ult…

That's how people used to view "imaginary" numbers...and the field of complex analysis laid dormant for 200 years. When a valid geometric interpretation was found that backed up the algebraic existence of these numbers, the field blossomed.

We're humans, we can't understand equations without knowing what they "mean."

Re: Quantum weirdness is everywhere in life

#69

Post by omalleyt »

n4r9 wrote: post #20
rogerbraun wrote: post #17

It's always a shame when the Copenhagen interpretation of quantum mechanics is presented as how reality works. Most of the perceived weirdness of QM comes from the leaps of faith required to make the Copenhagen interpretation work.

There's a lot of truth in that, and the orthodox interpretation is indeed riddled with incoherence. But what fascinates me is that after so much effort, the quantum community seems to be further away than ever from coming to a consensus on interpreting the theory. Every proposed interpretation does away with some foundational issue, yet introduces another in the process.

Pilot wave theory: the "weird effects" that QM displays are really just the result of space time being a thing that vibrates in a wave-like pattern influenced by mass.

And the reason this is cool is because when you put everyday objects in situations like that stated above, they exhibit quantum interference and everything else.

Re: Quantum weirdness is everywhere in life

#70

Post by coverup »

AnimalMuppet wrote: post #60
coverup wrote: post #58

Earlier quoted context omitted.

It's a shame when physics is presented as how reality works! Rather than what it is: our best model.

Physics is our best model? OK, I buy that. The Copenhagen interpretation? Not so much. It's an interpretation . The actual physics is in the equations. I can believe the equations without believing the Copenhagen interpretation, or any interpretation.

Right. The various interpretations are not so much science as philosophy. At best, they're scientific hypotheses, and that's only if they turn out to be falsifiable.
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