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An important quantum algorithm may be a property of nature

technologyreview.com

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Re: An important quantum algorithm may be a property of nature

#21

Post by knzhou »

Iv wrote: post #4

A reason why I allow myself some skepticism on the feasibility of quantum computing is that if it were possible, I would have expected evolution to have used it somehow. If it turns out that protein folding really use a quantum computation, I'll move quantum computers from the "too good to be true" category to the "probably revolutionary stuff that I will see in my lifetime" alongside with nuclear fusion and strong A…

This argument proves too much. By that same argument, nuclear fission, ordinary CPUs, steam engines, rockets, helicopters, jets, X-rays, radio waves, superconductivity, superfluidity, air conditioning, liquid helium, liquid nitrogen, the Haber process, the fractional quantum Hall effect, Doppler cooling, graphene, long-distance satellite communication, gravitational waves, and GPS corrections for relativity all don't exist, because nothing in life is designed like them or takes advantage of them. You've literally taken us back to the 1700s.

I know that it's fashionable to simply declare quantum computing is impossible, and there are some strong arguments in this direction, but this particular argument isn't one.

The general reason people believe quantum computing is possible is that it describes just about all the things I mentioned above absolutely perfectly, along with literally thousands of other phenomena, with no deviations ever measured. This gives us good reason to assume quantum mechanics actually works, and if it does, then it's possible for quantum computing to work. (Also, of course you need to account for quantum mechanics to account for protein folding. You literally can't have chemical bonds at all without quantum mechanics.)

Re: An important quantum algorithm may be a property of nature

#22

Post by knzhou »

nicwilson wrote: post #6

Hmm, there are several things I find strange about this article. There are 22 proteinogenic amino acids (admittedly two are rare, selenocysteine and pyrrolysine, but with rarity comes importance when they do occur). The search for the correct amino acid is not class balanced, e.g. the aromatics are much less common. The tRNAs are also not equally distributed, neither in the codon-anticodon pairing, the aromatics are…

This is all correct, and shows why both biologists and physicists don't take the conclusions of Patel's paper too seriously. Just aiming for "20" without any context for what that means is a bad kind of numerology. There's probably a grain of truth in the paper, but only enough to get to something like "20 plus or minus 10", not exactly "20".

Speaking as an MIT alumnus, some of the school's promotional material is glitzy on the outside and hollow on the inside. The MIT Tech Review's "Emerging Technologies" column is particularly bad. I've written numerous rants over the years rebutting incredibly misleading viral articles from it. It's a shame that people automatically trust it because of the MIT name.

Re: An important quantum algorithm may be a property of nature

#23

Post by goodmachine »

SolarNet wrote: post #19
xenadu02 wrote: post #11

Earlier quoted context omitted.

Use of the vast majority of the radio spectrum is not used by any form of life that we know of. Being able to communicate non-visibly without giving away our position audibly would be a huge advantage (until your predators/competitors figured it out). Life isn't generally suitable to the use of really high energies like X-rays because it damages cells. It isn't suitable for low energies because it is difficult to cre…

There are sea bacteria that "communicate" in the giga-hertz frequency. But the general point being that large portions of the range are used, like the visible spectrum and the thermal spectrum. x-rays aren't a unique physical phenomena, just a wave length of electromagnetic waves, which is a physical phenomena that life makes excessive use of (photosynthesis, vision).

> There are sea bacteria that "communicate" in the giga-hertz frequency.

Wow. Link?

Re: An important quantum algorithm may be a property of nature

#24

Post by Ultimatt »

nicwilson wrote: post #6

Hmm, there are several things I find strange about this article. There are 22 proteinogenic amino acids (admittedly two are rare, selenocysteine and pyrrolysine, but with rarity comes importance when they do occur). The search for the correct amino acid is not class balanced, e.g. the aromatics are much less common. The tRNAs are also not equally distributed, neither in the codon-anticodon pairing, the aromatics are…

Yup the biology bit is hocus pocus. If you read the single author arxiv paper referenced, its thinking is quite confused on the biology. The main thing discussed is hydrogen bonding between nucleotide pairs which doesn't fit the magic numbers. Then in an odd Q and A section its eluded to that mrna-trna interactions do, therefore it must be. Already the different bond lengths of the hydrogen bonding is known to be part of optimising that process. It says nothing about selection of nucleotides from the surrounding environment being magically quantum, rather than classically diffusive. That's something this blog article made up out of nothing.

Re: An important quantum algorithm may be a property of nature

#25

Post by knzhou »

Iv wrote: post #14
xenadu02 wrote: post #11

Earlier quoted context omitted.

Use of the vast majority of the radio spectrum is not used by any form of life that we know of. Being able to communicate non-visibly without giving away our position audibly would be a huge advantage (until your predators/competitors figured it out). Life isn't generally suitable to the use of really high energies like X-rays because it damages cells. It isn't suitable for low energies because it is difficult to cre…

Well, if we exclude all the visual spectrum, which is the most useful part of the RF spectrum for animals: transparent to water and atmosphere, reflects well on a lot of surfaces, has kilometers of range if there is line-of-sight, wavelength of a size making it possible to have lens and sensor cells small enough to fit an animal. But yes, the idea is that if there were a physical principle that would be super useful…

What's the explanation for why living things don't contain superconductors?

Of course: you need an extremely cold and clean environment, which is very hard to generate in a cell. And it wouldn't even be that useful for cells anyway.

The exact same reasoning applies to quantum computers.

Re: An important quantum algorithm may be a property of nature

#26

Post by wnkrshm »

Iv wrote: post #15
changoplatanero wrote: post #12

Earlier quoted context omitted.

lasers would be another one, right? Is there any lifeform that can make a laser?

Is there any lifeform that needs it? With light sensors that basically give us line-of-sight range, I don't see which problem organic lasers would solve.

What single-mode lasers do offer is a means of inconspicuous communication. If you can aim your communications channel at a receiver, you cannot easily be detected.

But life could do similar things with collimating reflectors, even for sound. Are there organisms that use geometry to shape sound to send a signal? I'm only aware of ones that use geometry to boost/tune their reception (e.g. owls).

Edit: Dolphins apparently

Re: An important quantum algorithm may be a property of nature

#27

Post by TheSpiceIsLife »

wnkrshm wrote: post #26
Iv wrote: post #15

Earlier quoted context omitted.

Is there any lifeform that needs it? With light sensors that basically give us line-of-sight range, I don't see which problem organic lasers would solve.

What single-mode lasers do offer is a means of inconspicuous communication. If you can aim your communications channel at a receiver, you cannot easily be detected. But life could do similar things with collimating reflectors, even for sound. Are there organisms that use geometry to shape sound to send a signal? I'm only aware of ones that use geometry to boost/tune their reception (e.g. owls). Edit: Dolphins apparen…

> Are there organisms that use geometry to shape sound to send a signal?

Wouldn’t this include pretty much any animal than can vocalise?

Re: An important quantum algorithm may be a property of nature

#28

Post by jessriedel »

knzhou wrote: post #22
nicwilson wrote: post #6

Hmm, there are several things I find strange about this article. There are 22 proteinogenic amino acids (admittedly two are rare, selenocysteine and pyrrolysine, but with rarity comes importance when they do occur). The search for the correct amino acid is not class balanced, e.g. the aromatics are much less common. The tRNAs are also not equally distributed, neither in the codon-anticodon pairing, the aromatics are…

This is all correct, and shows why both biologists and physicists don't take the conclusions of Patel's paper too seriously. Just aiming for "20" without any context for what that means is a bad kind of numerology. There's probably a grain of truth in the paper, but only enough to get to something like "20 plus or minus 10", not exactly "20". Speaking as an MIT alumnus, some of the school's promotional material is gl…

MIT Tech Review is no longer associated with MIT. The name is historical vestige. It's just another magazine like Popular Science.

Re: An important quantum algorithm may be a property of nature

#29

Post by jyounker »

Iv wrote: post #4

A reason why I allow myself some skepticism on the feasibility of quantum computing is that if it were possible, I would have expected evolution to have used it somehow. If it turns out that protein folding really use a quantum computation, I'll move quantum computers from the "too good to be true" category to the "probably revolutionary stuff that I will see in my lifetime" alongside with nuclear fusion and strong A…

Not quantum search, but sizable fraction of a second quantum coherence at room temperature:

https://arxiv.org/pdf/0906.3725.pdf

I suspect we’re just really bad at identifying quantum processes in living things.

Re: An important quantum algorithm may be a property of nature

#30

Post by TheOtherHobbes »

Iv wrote: post #14
xenadu02 wrote: post #11

Earlier quoted context omitted.

Use of the vast majority of the radio spectrum is not used by any form of life that we know of. Being able to communicate non-visibly without giving away our position audibly would be a huge advantage (until your predators/competitors figured it out). Life isn't generally suitable to the use of really high energies like X-rays because it damages cells. It isn't suitable for low energies because it is difficult to cre…

Well, if we exclude all the visual spectrum, which is the most useful part of the RF spectrum for animals: transparent to water and atmosphere, reflects well on a lot of surfaces, has kilometers of range if there is line-of-sight, wavelength of a size making it possible to have lens and sensor cells small enough to fit an animal. But yes, the idea is that if there were a physical principle that would be super useful…

Evolution is a relatively poor search algorithm that tends to get stuck at local maxima. Unlike science, it doesn't build maps and models for exploration and extrapolation.

So far as I know there's no general theory of theories which quantifies this, so there's no way to make predictions about the cut-off point for evolutionary invention.

But in a hand-wavy way, evolution's only feedback loop is first-order and binary - mutate and reproduce at a positive replacement rate, or not.

The feedback loop in science is more complex. Instead of being driven by a random search, "mutations" are guided by a creative model. This creates momentum in the model space which isn't available to evolution - which in turn makes it possible to discover more complex and less immediately accessible solutions.

It also makes it possible to build systems whose value is guaranteed, or at least strongly suspected, before resources are diverted to making them physical.

The bottom line is evolution is only ever going to find a small subset of all possible biological configurations, and that space is going to exclude many features that are available to science-driven search.

(Of course you can argue that scientific meta-search was a product of evolution anyway, so the distinction is academic.)

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