Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
6 online now:
Newest Member: popoi
Post Volume: Total: 915,815 Year: 3,072/9,624 Month: 917/1,588 Week: 100/223 Day: 11/17 Hour: 0/7


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Evolution vs. Thermodynamics
Richard
Inactive Member


Message 91 of 103 (19509)
10-10-2002 9:57 AM
Reply to: Message 90 by Brad McFall
10-09-2002 12:04 PM


The essence of entropy from a thermodynamic standpoint is simply that the tendency of the universe is to seek the minimal energy level. This is why all forms of free energy will diffuse and why chemical bonds will only spontaneously form when they will can establish that minimal bond energy. The problem that the slot causes for evolution is that at the temperatures and pressures that are necessary for the precursors of dna and rna to survive the amino acids will not SPONTANEOUSLY form. This why abiogenisis is a problem where the origin of life is concerned. To my knowledge no expiriment has yet been perfomed that will give spontaneous development of the necesary amino acids unless enormous expirimenter interference is involved. Every abiogenis scenario postulated from the prebiotic soup to clays to hydrothermal vent and far from equilibrium thermodynamic fail either due 1: reaction is not spontaneous at the suggested temp and pressure so experimentor interference is needed. 2: the environment would destroy the amino acids at a rate that would not leave sufficient concentrations or acids to combine. 3) No mechanism is shown to account for the complex specified information that is inherent in the genetic code.

This message is a reply to:
 Message 90 by Brad McFall, posted 10-09-2002 12:04 PM Brad McFall has not replied

Replies to this message:
 Message 92 by Randy, posted 10-10-2002 12:51 PM Richard has replied

  
Richard
Inactive Member


Message 93 of 103 (19566)
10-10-2002 4:15 PM
Reply to: Message 92 by Randy
10-10-2002 12:51 PM


quote:
Originally posted by Randy:
quote:
Originally posted by Richard:
The essence of entropy from a thermodynamic standpoint is simply that the tendency of the universe is to seek the minimal energy level. This is why all forms of free energy will diffuse and why chemical bonds will only spontaneously form when they will can establish that minimal bond energy. The problem that the slot causes for evolution is that at the temperatures and pressures that are necessary for the precursors of dna and rna to survive the amino acids will not SPONTANEOUSLY form. This why abiogenisis is a problem where the origin of life is concerned. To my knowledge no expiriment has yet been perfomed that will give spontaneous development of the necesary amino acids unless enormous expirimenter interference is involved. Every abiogenis scenario postulated from the prebiotic soup to clays to hydrothermal vent and far from equilibrium thermodynamic fail either due 1: reaction is not spontaneous at the suggested temp and pressure so experimentor interference is needed. 2: the environment would destroy the amino acids at a rate that would not leave sufficient concentrations or acids to combine. 3) No mechanism is shown to account for the complex specified information that is inherent in the genetic code.
This has all been discussed and answered at several places on this thread, including just above. Please read posts 50, 54, 66 and 91 of this thread for discussion of points 1 and 2, and of course "experimenter interference is needed since conditions present on the prebiotic earth are no longer present in nature. As to 3, "complex specified information" is not part of thermodyanmics. This has also been discussed on this thread.
I don't expect it will ever be possible to prove exactly how life arose on earth or prove that it did have a natural origin. The best that will be done is to develop scenarios that are more and more plausible. However, to prove that the second law prevented life from arising naturally you must show exactly which reactions where absolutly necessary for abiogenesis and show that there were no possible conditions on the prebiotic earth where these reactions could have occured. You don't and can't know this information therefore you can't prove that the second law prevented abiogenesis.
BTW your description of entropy and the reasons for chemical bond formation are not very precise.
In statistical thermodynamics the entropy may be defined as Boltzmann's constant time the log of the number of quantum states of a system with equivalent energy but this relationship only holds under very specific conditions and I don't think that anyone has yet started with statistical mechanics and derived a general statement of the second law of thermodynamics that holds in all conditions.
In classical thermodynamics, where the second law is defined (though not dervided mathematically), the entropy change in a process is the integral of the differential of the heat (reversible heat flow) divided by the absolute temperature when the process is carried out in a reversible fashion. It is the sum of the changes in this quantity in a system and its surroundings that can never decrease and that must increase for the universe as a whole (system + surroundings) in any irreversible (ie real) process. In equilibrium thermodynamics the direction of a reaction is determined by the free energy change which is influenced by reaction conditions. Chemical bonds form when the enthalpy of bond formation is negative (heat is released) and is greater than the product of the reduction in entropy times the absolute temperature under the conditions of the reaction. They are trying establish "minimal bond energy" whatever that means. Reactions that are not favorable can be driven if they are coupled to other reactions that are favorable.
Randy

Thanx for the specific posts I will go back and review.
By minimal bond energy I mean that all chemical bonds will spontaneously seek the most stable bond configuation. This is in line with the concept of entropy that says that all systems will tend toward the lowest possible enery distrbution. Whether you are dealing with "ideal" gasses or heat engines this will always be true. The slot does hold under all circumstances there are no exceptions to this law. However it follows from the second law that in order to reverse the natural tendency work must be done to reverse this tendency. The point about expirimenter interference is that the expirementer must drive the reaction in other work is performed because amino acids will not form spontaneously. To date no one has been able to synthesize rna or dna under labratory conditons and these condition will be far more favorable than they ever woluld be on the prebiotic earth. As for CSI the point is that thermodynamically under the conditions that exist today and have existed for many millions of years and these are the conditions under which life has flourished.(if you believe in evolution) The probablily of spontaneous coding is for all purposes zero. No one knows what the conditons were one the prebiotic earth but since even the simples amino acid will be quickly annilated if conditons are too extreme you have to assume that abogenis took place under conditons close to what exists today in terms of viable tempeatures and pressure since you need the amino acids to survive long enough and in sufficient quantities to allow for self organization. I will now go and review the previous posts. I am looking forward to you reply.

This message is a reply to:
 Message 92 by Randy, posted 10-10-2002 12:51 PM Randy has replied

Replies to this message:
 Message 94 by Randy, posted 10-10-2002 5:45 PM Richard has replied

  
Richard
Inactive Member


Message 95 of 103 (19639)
10-11-2002 12:08 PM
Reply to: Message 94 by Randy
10-10-2002 5:45 PM


quote:
Originally posted by Randy:
quote:
Thanx for the specific posts I will go back and review.
By minimal bond energy I mean that all chemical bonds will spontaneously seek the most stable bond configuation.
But systems can get locked into non optimum metastable states for ever if the activation energy necessary to get back over the hump between the metastable and the equilibrium state is not supplied.
quote:
This is in line with the concept of entropy that says that all systems will tend toward the lowest possible enery distrbution.
Actually the broadest possible energy distribution may be a better way to state it.
quote:
Whether you are dealing with "ideal" gasses or heat engines this will always be true. The slot does hold under all circumstances there are no exceptions to this law.
This is true for macroscopic systems but there are deviations in microscopic systems. We have discussed this a bit before. Here are the links that were brought up then.
Page not found | American Institute of Physics
Abstract Link
http://arxiv.org/ftp/cond-mat/papers/9901/9901258.pdf
Good article but the slot still hold even here since at base the slot deals with energy transfer in other words unless the bead was temporarily at a lower energy level than the water no energy could have been xferred. I had trouble linking to the abstract I will try again later.
quote:
However it follows from the second law that in order to reverse the natural tendency work must be done to reverse this tendency.
Energy must be supplied true. That’s why it is fortunate that we are not dealing with an isolated system.
The slot hold true for all system closed isolated and open.
quote:
The point about expirimenter interference is that the expirementer must drive the reaction in other work is performed because amino acids will not form spontaneously. To date no one has been able to synthesize rna or dna under labratory conditons and these condition will be far more favorable than they ever woluld be on the prebiotic earth.
Because no one has done it to date you assume that no one will. This assumption has not been justified about other scientific studies in the past. Why are you so sure that it is now. How do you know that the conditions will be far more favorable when you don’t know what the conditions were? I do suppose that we must use more favorable conditions though since we probably don’t want to wait 100,000,000 years to see what happens.
The spontaneousness of the reaction is the key. Once the conditions are correct the self organization will happen very quickly. Remember we are dealing with chemical reactions. We are going from raw elements to amino acids this should not take millions or years. You must assume that the conditions were favorable enough for amino acid generation and amino acid survival.This is what the experimentor does. Based on the known laws of chemistry he postulates certain conditions because he know that a given set is required for the reaction to take place. We dont have life yet just basic building blocks. Your millions or years comes in when you have to make the leap from blocks to life.
quote:
As for CSI the point is that thermodynamically under the conditions that exist today and have existed for many millions of years and these are the conditions under which life has flourished.(if you believe in evolution)
CSI? It is well known that conditions on the prebiotic earth would have been quite different. What is your point?
quote:
The probablily of spontaneous coding is for all purposes zero.
Ah the old bogus post hoc calculation of probability. In my this really has little to do with the second law and has been answered many times before.
This has everything to do with the slot because dna and rna are at a higher bond energy than the individual amino acids they are made from. what this means is it will not happen spontaneously but had to go against the energy gradient. What the slot does it it tells you is that without energy and a way to couple the energy in a useful fashion to reverse the natural tendency tranfer of energy will not happen from a higher energy level to a lower energy level. Thats why even in the above experiment we know that the bead must have been at a lower energy level at least for two seconds. so it absorbed enegy from the colliding water molecules. once the two reached energy equilibrium the further enegy added by the optical tweezers began to xfer energy back to the water. All of this is in line with the laws of thermo. Since dna and rna are at a higher level of bonding enery what is the mechanism that spontaneously organized such a complex molecule by virtue of the organization gave it the specificity necessary to code. The reason I invoke probability is that the organization of dna goes against the energy flow. What is the probability of energy being xferred from a lower energy level to a higher energy level spontaneously. (Spontaneous in this case meaning in absence of a mechanical or biological means or coupling energy to reverse the flow)
quote:
No one knows what the conditons were one the prebiotic earth
Exactly my point.
quote:
but since even the simples amino acid will be quickly annilated if conditons are too extreme you have to assume that abogenis took place under conditons close to what exists today in terms of viable tempeatures and pressure since you need the amino acids to survive long enough and in sufficient quantities to allow for self organization.
How do you know what I have to assume? What about the presence of temperature gradients? Macromolecules created at one temperature could diffuse to regions of lower temperature where they would be stable. What about catalysts and coupled reactions? There are far too many unknowns here to claim that you can show that the second law prevents abiogenesis. BTW since you are only talking about abiogenesis are you conceding that the second law does not prevent evolution.
I agree that that they can diffuse region where the temp is mild enough to survive. My point is that the scenarios suggested for the spontaneous generation are unrealistic. the primordial soup suffers form the need for a reducing atmosphere which brings with it assorted acids hcl h2so4 etc. even the hydrothermal vent theory has problems since at those temps amino acids would not last even a few hours and then there is the additonal problem of degrading of the acids by water. and all these scenarios are covered by the slot. We know that catalysts can alow reactions to take place at safer temps but again in the prescense of waters filled with various acids minerals and other compounds that will be much more reactive you get back to the same problem. you cannot consider evoultion until you solve the problem of abiogenis. Abiogenis is an implict assumption in all evolutionary scenarios. My claim is that life does not violate the slot. Abiogenis does because you must be able to show the intermediate spontaneous steps for the self organiztion of elements to amio acids and amino acids to dna and rna and each step must obey the first and second laws of thermodynamics.
Randy


This message is a reply to:
 Message 94 by Randy, posted 10-10-2002 5:45 PM Randy has replied

Replies to this message:
 Message 96 by Randy, posted 10-11-2002 4:30 PM Richard has replied

  
Richard
Inactive Member


Message 97 of 103 (19861)
10-14-2002 3:11 PM
Reply to: Message 96 by Randy
10-11-2002 4:30 PM


quote:
Originally posted by Randy:
Richard wrote:
quote:
Good article but the slot still hold even here since at base the slot deals with energy transfer in other words unless the bead was temporarily at a lower energy level than the water no energy could have been xferred. I had trouble linking to the abstract I will try again later.
Experimental Demonstration of Violations of the Second Law of Thermodynamics for Small Systems and Short Time Scales
G. M. Wang,1 E. M. Sevick,1 Emil Mittag,1 Debra J. Searles,2 and Denis J. Evans1
1Research School of Chemistry, The Australian National University, Canberra ACT 0200, Australia
2School of Science, Griffith University, Brisbane QLD 4111, Australia

(Received 04 March 2002; published 15 July 2002)
We experimentally demonstrate the fluctuation theorem, which predicts appreciable and measurable violations of the second law of thermodynamics for small systems over short time scales, by following the trajectory of a colloidal particle captured in an optical trap that is translated relative to surrounding water molecules. From each particle trajectory, we calculate the entropy production/consumption over the duration of the trajectory and determine the fraction of second law—defying trajectories. Our results show entropy consumption can occur over colloidal length and time scales. 2002 The American Physical Society
In terms of statistical mechanics the second law represents a tendency. This tendency is overwhelming with large collections of particules over long time scale but significant fluctuations can occur in smaller systems at short time scales as this paper demonstrates.
quote:
The slot hold true for all system closed isolated and open.
While the second law may hold in all macroscopic systems it is only in isolated systems that entropy must always increase as I think you know. It is also quite difficult to figure out exactly how to apply the second law in open systems that are not at least fairly close to equilibrium for the purpose of calculating entropy changes in processes. At least I think irreversible thermodynamics are a bit difficult especially at the statistical level. Maybe you don't but I do.
quote:
This has everything to do with the slot because dna and rna are at a higher bond energy than the individual amino acids they are made from.
Actually DNA and RNA are not made from amino acids at all. DNA codes for the production of amino acids through messenger RNA but DNA and RNA are of course made from nucleotides. Perhaps you should read a basic biochemistry text. I like Biochemistry by Chris Mathews and Ken van Holde but I am probably biased because I did a significant fraction of my Ph.D. research in Ken van Holde's lab many years ago.
quote:
what this means is it will not happen spontaneously but had to go against the energy gradient. What the slot does it it tells you is that without energy and a way to couple the energy in a useful fashion to reverse the natural tendency tranfer of energy will not happen from a higher energy level to a lower energy level.
What the second law says is that transformations from one equilibrium state to another equilibrium state in thermodynamically isolated systems will lead to an entropy change that is greater than or equal to zero. There are many open systems far from equilibrium that spontaneously order. Examples are the Benard Instability in viscous solutions under temperature gradients and oscillating chemical reactions such as the Belousov-Zhabotinsky reaction.
quote:
Abiogenis is an implict assumption in all evolutionary scenarios.
The common descent of all life on earth from previous ancestors going back to single celled organisms depends not one bit on how the first cells arose or appeared.
quote:
Abiogenis does because you must be able to show the intermediate spontaneous steps for the self organiztion of elements to amio acids and amino acids to dna and rna and each step must obey the first and second laws of thermodynamics.
As I said above DNA and RNA are not made from amino acids but that is beside the point. The formation of biopolymers involves chemical reactions. Chemical reactions will proceed if the free energy change is favorable. Unfavorable reactions can be driven if they are coupled to favorable ones. You don’t know what the reaction conditions were. You don’t know what sequence of reactions were absolutely required, how they may have been catalyzed or what reactions may have been coupled together. You don’t whether or not the currently proposed scenarios actually reflect what may have happened. Without this knowledge your arguments against abiogenesis do not and can not have the force of the second law of thermodynamics behind them.
Many creationists, some of whom I expect know far more about thermodynamics than you do, understand that the second law does not prevent abiogenesis or evolution and I have given links to the web pages of a couple of them in previous posts but here they are again.
http://members.aol.com/steamdoc/writings/thermo.html
The page you were looking for doesn't exist (404)
You are recycling arguments that have been discussed in detail in the posts that I asked you to read before.
Randy
PS I had a bit of difficulty sorting out your replies from my post. Please use some way to distinguish the two and the preview function to see if it worked in the future.

You are correct dna etc is not composed of amino acids amines are used by dna to construct the protiens that drive biological functions.
I am saying that the slot put constraints on the direction of energy flow. For example the expiriment that showed loss of entropy at the micron level. The slot does not forbid the loss of entropy in isolated or open systems. This experiment qualifies at the very least as an isolated system. So it is not a true violation of slot for it to be a violation the expirement would have to show that energy flowed from a lower level to a higher level spontaneously. this was a isolated system far from equilibrium and localized entropy fluctuations are permitted. what the experimentors did was quantify the old argument between boltzmann and loschmsmidt which was what is the upper bound of the scale you would see the fluctuations on and for how long. No one is claming that this will allow for the self ordering of life from non life.
Now back to abiogenis at some point you have to say what are the minimal conditions to expect for raw elements to spontaneous combine not only form the base products of life but contribute to thier surivability long enough for the base element to under go another spontneous reaction to actually live. Since we are speculating from the standpoint of a prebiotic earth no one knows the initial conditions but it is an unworthy dodge to fall back to that as a cover when life as is here on earth presents some constaints.
1:all life is carbon based. 2. all life requires either rna or dna and amino acids. Now I agree entirely that in the prescense of catalysts the conditons can be made more favorable. To date however no one has postulated how you get both the base materials and survialbilty in such a harsh environment because in the presence of hcl h2s02 hg various minerals other reactive elements which certainly would be present on earth at this early stage there are other reactions that are far more thermodynamicaly favorable and the would destroy the base material and the catalysts. Think of our own bodies our stomachs contain very dilute hcl. Do you think that if you had the base element that form dna in our stomach along with whatever catalyst you need to spontneously form the more complex compounds do you think they would form no the hcl would destoy the bases and probably the catalyst. This is the reason slot stand in the way you cannot always say no one knows the intial conditons. But we do know the constraints that life puts on the initial conditions.
There are creationists and non creationists that know more about thermodyamics but it does not change the fact that the reactions must follow thermodynamic constraints. Until some one synthesyses dna in a lab in conditons that could reasonably be expected to have occurred on the primitive earth all you have are just so stories and woefully unrealistic experiments. But the overall path must be consistent with its laws. Taking in to account the most probable conditons on the primitive earth (given life as we know it) where is the thermodyamically consistent path that spontaneously generates the base constiutents of life make them live and provide a self replication code dna?
Abiogenis is the fly in the ointment of evolution. There would be no rehashing of these objections if you had a resonable and testable hypothesis to account for abiogenis. You have to have spontaneous generation of life from non life and this includes information coded into it so it can replicate itself otherwise it will go extinct and this all has to be thermodynamically possible.

This message is a reply to:
 Message 96 by Randy, posted 10-11-2002 4:30 PM Randy has not replied

Replies to this message:
 Message 98 by Percy, posted 10-14-2002 4:27 PM Richard has replied

  
Richard
Inactive Member


Message 99 of 103 (20037)
10-16-2002 4:02 PM
Reply to: Message 98 by Percy
10-14-2002 4:27 PM


quote:
Originally posted by Percipient:
Richard writes:
Abiogenis is the fly in the ointment of evolution. There would be no rehashing of these objections if you had a resonable and testable hypothesis to account for abiogenis.
Though we always know more today than we did yesterday, in science there will always be things we don't know. At present we do not know the process by which the first life came to be. We may never know, since after all there's little evidence left after 3.8 billion years. Even if we're eventually able to piece together a workable scenario, there will be no way of knowing if life's origin followed that scenario or some other yet undiscovered.
You therefore are not objecting to evolution on any valid grounds. You are not saying, for instance, that the abiogenesis process currently accepted by scientists violates thermodynamics and is therefore impossible, because there is no such process. You can't even say that you've examined all the tentative scenarios proposed by scientists and found that they all violate thermodynamics, because not one of them does. Your objection therefore reduces to, "I don't believe abiogensis could have happened because if it did I believe it would have violated thermodynamics."
This is not to say you are wrong, just that you have no evidence supporting your belief. I think this belongs in the "argument from personal incredulity" category.
--Percy
[This message has been edited by Percipient, 10-14-2002]

Not from incredulity but from lack of scientific evidence. You cannot have it both ways. Abiogenis is the foundation for evoulution. Neo Darwinism mechanisms are random chance coupled with natural selection. But natural selection can only operate on living forms.
Again it is not a case of all the possible scenarios. We know that life only exists on this planet within certain range of conditions etc above a certain temp and or pressure life ceases to exist at all levels of complexity. Since the earliest forms had to be very simple probably not even as complex as the viruses and bacteria known today that places constraints on the environment. What I am saying is based on all that is currently known in all of the physical and life sciences and assuming that the early life scenarios are based on this knowledge we should be able to run plausible scenarios and see if they suceed or fail. If they fail either the theory needs to be adjusted based on the expiriment or the expiriment is not an accurate representation of conditions or a combination of both. The reason that thermo stands in the way of abiogenis is that there are so many variable involved in the spontaneos generation of life that to have all of them come together at once is shown to be statistically impossible. Consider the simplest possible life form you would have to have all of the necessary catalysts to make the reactions for favorable for the building blocks of life all there at the same time under conditions that would not degrade them to where they would be useless and then the life form from the very begining must have the necesary genetic complexity to reproduce and do error correction to offset the random mutations and damgage caused by its environment. This is where thermo stands in the way. The probabilities of all the reactants being there at the same time in the necessary concentrations at thermdynamically favorable conditions for all is next to impossible. this is where thermo stands in the way. Abiogenis reminds me of the problem with the fossil record. If the fossil record was truly compelling then punctuated equilibrium would never have been developed. If Abiogenis was so obvious then we should be able to devise resonable simulations that support it and take what we learn from the failures to devise more accurate scenarios.
For example lets take the bases of the miller urey expiriment a reducing atmosphere. Now if life was here 3.8B years ago does the geological evidence supportive of a reducing atmosphere. If yes then what does that imply for the prebioic soup. what is a resonable range of dissolved minerals in the soup. A resonable temp range of the soup. if volcanism was a source of the reducing atmosphere what does that imply as to the ph of the soup. Based on the atmospheric conditions how much uv of gamma radiation could be expected to come through. Yes we do not know exact answers but we could postulate a range for these conditions. What is happening today is just believe us it happend! Do not ask us to present plausible scenarios and test them out. Why should abiogenisis be exempt from rules that apply to every other theory.

This message is a reply to:
 Message 98 by Percy, posted 10-14-2002 4:27 PM Percy has replied

Replies to this message:
 Message 100 by Randy, posted 10-16-2002 6:25 PM Richard has not replied
 Message 101 by Percy, posted 10-16-2002 9:02 PM Richard has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024