Sunday 15 October 2017

Quantum Biology much ado about noting

First apologies for not posting for a while I did not finish S383 the third TMA was a nightmare all waffle and no maths. A very disappointing course my reccomendation for those who want a mathematical based course is to avoid this one like the plague. Anyway I am now on restricted status which means under the new regulations I can't take any more OU courses unless I apply for removal from my restricted status. I did manage to salvage something namely I had built up enough credits for a second open degree without honours. If I want an honours degree in mathematics then I would have to take a new 1st level course in Statistics, another 1st level course and the second level course in mathematical methods. I can't really see me taking this so that would appear to be the end of my open university studies

Anyway I digress the main focus of this post is on the allegedly new science of quantum biology the claim has been made that biological systems exhibit all the mysterious effects associated with quantum mechanics such as non-locality, entanglement and bose Einstein condensation a short overview of these claims is given by Jim Al Khalili (Who I would have thought known better but I guess he has to get his money from somewhere and how better than to jump on a bandwagon)

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjp2K27hvPWAhWIChoKHYr6Dz4QtwIIKDAA&url=https%3A%2F%2Fwww.ted.com%2Ftalks%2Fjim_al_khalili_how_quantum_biology_might_explain_life_s_biggest_questions&usg=AOvVaw2SeqAMJK9gfXHM97NcUGMU


I have severe doubts about the whole thrust of this (as those who have read my earlier posts on quantum mechanics might have guessed)

Just a few points

a) It is highly surprising that phenomenon such as Bose Einstein condensation occur at room temperatures usually such effects manifest themselves at very low temperatures. The wet noisy enviroment associated with biological systems would seem to mitigate against this

b) The fact that experiments seem to have established long range electron coherence in photo-synthesis and other similar processes should not necessarily be seen as evidence for non-locality, the conditions in which so called entanglement occur and violation of the Bell inequalities are usually quite specific involving the emission of two particles from a common source such that their net angular momentum is zero. In photosynthesis there would appear to be no such initial conditions

c) Khalili and others make the common fallacy of assuming that the so called wavefunction is a physical entity and not as the Born interpretation would have effectively the square root of a probability density function or probability amplitude whose modulus squared gives rise to a probability density function. Thus the pictures that Khalili show of quantum tunneling are pictures of a probability density function not of an electron or other particle spread out over all space.

d) Quantum superposition is not an actual superposition but a superposition of possible states. The idea that some people have that before a measurement is made a quantum system is in a state of limbo which collapses to one of the possible states on measurement is misleading to say the least. Before measurement the observer does not know which one of the many possible states the system will be found in. He or she can only assign certain probabilities in accordance with the physical setup On measurement the system will be found to be in one of those states and so the superposition of possibilities 'collapses' to the one found on measurement. If the experiment is repeated a sufficiently large number of times then the system will have been found in each one of the states in accordance with the probabilities initially assigned. However because of the random nature of quantum events I can never tell by a single measurement what state the system will be found in.

e) The above interpretation simplifies all the agonising over the Aspect experiment. On the above interpretation a given observer A at his or her station will either measure a particle to have spin up or down. However once A has done this he or she will immediately know the result of B's measurement But of course as B has no way of knowing what A's measurement is then as far as he is concerned his particle could still be measured with spin up or spin down. There is no faster than speed of light communication caused by A's affecting B's particle.

So for all those reasons even if it were true that biological systems are exhibiting the so called mysterious aspects of quantum mehcanics. There is a perfectly rational explanation based on a purely statistical interpretation of quantum mechanics. Particles do not split in two when passing through slits, Particles do not traverse all possible paths at once and there is definitely no faster than light communication between separated quantum systems.

However recent experiments have caused doubt on whether or not the long correlation times observed in photosynthesis are due to quantum effects.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5559008/

A good overview of how photosynthesis is modelled is given by this MSc thesis which again shows that there is no need to invoke the mysterious aspects of quantum mechanics to explain the electron coherence.

https://arxiv.org/abs/1503.03277

Also this web site is the blog of a condensed matter physicist who has been very sceptical about the quantum biology bandwagon

http://condensedconcepts.blogspot.co.uk/

So for all the above reasons I think it is safe to say that the Quantum biology bandwagon is truly much ado about nothing




2 comments:

  1. The UK Biotechnology and Biological Sciences Research Council and the US National Science Foundation currently have an open grant call for research proposals in Quantum Biology, so presumably they do not think that it is "much ado about nothing"

    https://www.ukri.org/opportunity/2020-bbsrc-nsf-bio-lead-agency-opportunity/

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  2. well I don't deny that quantum mechanics may or may not be useful in modelling biological systems. What I do deny is the interpretation that Jim Kahlili and others place on it. Namely that it involves electrons being in more than one place at once or that signals can travel faster than the speed of light
    An electron is not in more than one place it's probability density function is. So called nonlocality does not involve signals travelling faster than the speed of light merely an update of my knowledge about a system. So that if before a measurement occurs I don't know which of two possible outcomes will entail, but after I have made my measurement I will know a) my result and instantaneously the result of the other persons measurement because if the law of conservation of angular momentum. That is where there is unjustified hype not the application of the mathematics of quantum to biological systemes but the interpretation of quantum mechanics. To coin a phrase it's not mystical Just statistical :)

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