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Re the wavefunction: it contains all the possible locations of the particle, but obviously, since we don't know where the particle IS, there IS a hidden variable: the location of the particle.
That's not true. Please read the wiki about Bell's theorem, or any book on QM.
I should add that I don't think this point is important for the topic of this thread. Whether or not the world is fundamentally random is functionally irrelevant when you deal with chaotic systems, because even without QM you will never know the initial conditions precisely, and those uncertainties grow exponentially with time. The details of mutations and evolution on short time scales are certainly chaotic.
It isn't just that we don't have all the data. It means that the data not only cannot be measured for practical reasons, it means that no amount of measurement, by any system, conscious or unconscious, technologically advanced or otherwise, can ever find that data.
Again, I understand that. From everything I read about QM in the past, I got the impression that it was indeed a lack of information that made it probabilistic, not the fact that the process was random in the absolute sense. I might be wrong, but that's how I understood it.
Fredrik said:
This isn't true at all. What you're saying here (or at least statements that are equivalent to yours in every way that matters) have been proven wrong by experiments. Your claim contradicts quantum mechanics, but the experiments don't. It is completely false to say that the particle has a specific location. The wave function is the best possible answer to the question of where the particle "is". It's not just that we use a wave function when we we don't have complete information. The wave function really is all the information.
You're saying that the wavefunction doesn't represent a range of possibilities but the actual location of the particle/wave which is the ENTIRE wavefunction ???
ETA: That might not have been very clear. Are you saying that it doesn't represent a range of possibilities about its location, but rather it's actual location i.e. the entire wavefunction. ???
Sol Invictus said:
That's not true. Please read the wiki about Bell's theorem, or any book on QM.
Well apparently that won't do any good. Either I can't read properly, or I can't intepret what I read properly properly.
I should add that I don't think this point is important for the topic of this thread. Whether or not the world is fundamentally random is functionally irrelevant when you deal with chaotic systems, because even without QM you will never know the initial conditions precisely, and those uncertainties grow exponentially with time. The details of mutations and evolution on short time scales are certainly chaotic.
ETA: That might not have been very clear. Are you saying that it doesn't represent a range of possibilities about its location, but rather it's actual location i.e. the entire wavefunction. ???
Let me try to clear that up. The wavefunction gives the probability of finding the particle at some position. It is a function of position, and its value (really its norm squared) at some point is the probability density for finding the particle at that point. Because it is a wave, it can interfere with itself (as in the double slit experiment). A theory in which the particle is really at some specified position all the time cannot do that - that's actually proven by a mathematical theorem, Bell's theorem.
Please think again about double slit. Remember, the interference occurs when no observation has been made at the slits (it doesn't occur when an observation has been made, because in that case the wavefunction collapses). So the interference has nothing to do with observation perturbing the experiment - quite the contrary.
Well apparently that won't do any good. Either I can't read properly, or I can't intepret what I read properly properly.
Well, the statement of the theorem is "No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics." The particle actually having a location is a hidden variable.
Originally Posted by jimbob
Skeptgirl, the reason that I dislike dsecrbing evolution as nonrandom is that it implies that there was an inevitability about the evolution of the particular species that we see today.
I see evidence it is the case. The flying bat and flying birds both fly by 2 wings. The Thylacine resembles predators which evolved via a separate lineage from Thylacines. There are a limited means of locomotion, of vision, of consumption, circulatory systems, muscle systems, digestion, and excretion.
I did mention that some niches are very likely to be filled, for example flight, large grazing herbivores, and their predators (I was thinking especially of wolves and thylacines).
A probabilistic treatment allows you to say that these were likely, and turn up in any suitable environment, whilst other niches might only infrequently get filled. That some unlikely events will happen is also almost certain....
I would say that at the time of the KT impact, there was no inevitibility of humanity evolving. something would have, but what depended a lot on (skewed) chance.
The last common ancsetor of chimps and humans is thought to have lived about 8MY ago. Obviously the descendents of some offspring hafd more chimp-like traits, whilst others had more hominid-like traits (although probably almost imperceptably so). A slight difference in the weather slightly altering the timing of mating could have meant that neither hominids nor chimps would have evolved, but smoething else...
Originally Posted by jimbob
If we had ten absoultely identical Earths, just before the KT impact and let evoultion run its course; due tothe fact that quantum events do seem to be truely random, and chaotic systems magnify these effects to affect macroscopic events, then you would get different species 65MY later in each "version". There might be humanity, or something akin to it, or there might not. It was not inevitable that our environmental niche was going to be filled
.
Rather than looking at your example, let's ask a couple different questions. We've already said there is a random component in evolution. The question is how significant is that random component to the outcome, and does mijo's mathematical model describe evolution? I have already answered that mijo's model only describes a small piece of evolution and is not a model of actual evolution any more than a model of reproduction is a model of evolution.
Again you need to look at thetimescales. For geological timescales, I would say that even the environment is significantly altered by random influences, so what organisms are adapting to is altering randomly.
Over a shorter timescale, where the environment could be considered to be altering nonrandomly, then the selection pressures for different traits would be altering nonrandmly, then there would be a predictable components, but how a prtticular niche is filled, or whether it is filled would still be a probabilistic event. In a cave, organisms will loose their eyes, as they "cost". On an island with no predator, many birds will loose flight, as that is a "cost".
So the question here is then, how predictable and how random is evolution? Is the question just a matter of ideology, or is it a matter of evidence?
First I say, forget the hypothesis we wouldn't be here if it weren't for the random event of an asteroid hitting the Earth 65 million years ago. It's just someone's hypothesis. We seem to so readily accept such hypotheses as facts when they are no such thing.
Would human intelligence have evolved if the asteroid impact had not occurred? From the evidence it is more likely than not that human intelligence would have evolved eventually. Perhaps the timing would have differed. What's a million years give or take in a 14.5 billion year old Universe and on a 4.5 billion year old Earth? Not much.
I would say it is certain that human intelligence would not have evolved. You could argue about any similar level intelligence...
Dinosaurs had been around for 160MY without evolving tool-using social-intelligences (unless they nuked themselves...).
Mammals would have found it difficult to evolve sufficient size in the presence of dinosaurs already occupying many of the "intermediate" niches. If there are large predators, the offspring of small animals (aka dinner) will not evolve into large animals as they just become too tempting for the large carnivores. The would also have to compete against large animals already occupying the niche.
Which features of humans would have predictably evolved and which features would have been random? I suggest the evidence points to hands and brains as predictable results of evolution. Those in turn result in technology.
I would disagree, slightly. Obviously larger brains was a viable evolutionary strategy, but a slight alteration in conditions, and the extra energy cost of a larger brain coollud have offset the benefit. I would imagine that pandas are less intelligent than their ancestors.
But there are no technological societies within radio wave range of the Earth. Maybe not but it is a very large and very old Universe relative to our short time spent in the technological era. Considering the vastness of the Universe, and the variety of conditions we have detected just in our solar system, and considering what we have recently discovered about how nonrandom the evolution of life really is, the hypothesis life will evolve anywhere in the Universe the conditions allow it is supported by the most evidence.
For so long we've been operating under the hypothesis life on Earth is so unique that it could have evolved only rarely, and development of technology must be even more rare, we've just come to accept these beliefs as if they were as factual as the laws of physics. That is as ignorant as the belief humans are more than one step further along on the evolutionary path than the other great apes. We have been raised on these egocentric assumptions as if science actually supported the conclusions.
Nonsense! Get a telescope. Look up into the night sky. You can see billions of stars and trillions of galaxies each with billions more stars in them. Planetary systems are as common as dirt. And abiogenesis and evolution are as predictable as the rate molasses runs downhill on an Earth-mass body.
Would life evolve anywhere in the Universe that the initial conditions existed? I would conclude the evidence is a definite yes on that one. Read up on the current research and hypotheses on abiogenesis. You can draw almost no other conclusion. (Unless of course, you don't read up on the current state of the science of abiogenesis.) Would intelligence and technological species evolve given the conditions? Of course they would. Even if an asteroid calamity sped the process up a tad on Earth, that is not evidence it would not have eventually occurred.
Instead of sticking with old hypotheses and old premeses, take a look at the state of the evidence today. It isn't ideology, it is evidence that supports the conclusion evolution is not a random process. Why do you think the research cited in the OP specifically makes that statement? Because they specifically proposed a question which answers that question. If evolution is random, X will occur. If evolution is not random, Y will occur.
I think this is another misunderstianding of the positions (or culture?) of those with a physics-based background.
Just because somemthing is random doesn't automatically mean it is unlikely. It just means that individual events are not repeatable for the same initial conditions.
I would agree with you about the odds of life elsewhere.
Derail:
And here is an interesting article in this weeks nature (currently not behind a paywall), demonstrating behaviour that neurons would need.
Cellular memory hints at the origins of intelligence Slime mould displays remarkable rhythmic recall
Learning and memory — abilities associated with a brain or, at the very least, neuronal activity — have been observed in protoplasmic slime, a unicellular organism with multiple nuclei.
When the amoeba Physarum polycephalum is subjected to a series of shocks at regular intervals, it learns the pattern and changes its behaviour in anticipation of the next one to come1, according to a team of researchers in Japan. Remarkably, this memory stays in the slime mould for hours, even when the shocks themselves stop. A single renewed shock after a 'silent' period will leave the mould expecting another to follow in the rhythm it learned previously. Toshiyuki Nakagaki of Hokkaido University in Sapporo and his colleagues say that their findings “hint at the cellular origins of primitive intelligence”.
Yes it does, and why do you mention rule 30? I looked it up, and that system is obviously deterministic, but that doesn't in any way imply that evolution is.
Of course with total knowledge technically randomness would be deterministic...
Mammals would have found it difficult to evolve sufficient size in the presence of dinosaurs already occupying many of the "intermediate" niches. If there are large predators, the offspring of small animals (aka dinner) will not evolve into large animals as they just become too tempting for the large carnivores. The would also have to compete against large animals already occupying the niche.
I would argue that a lot of this is the weak anthropic principle,
We think we are special becaues we exist.
Of course we can observe the universe, if we didn't exist, the universe would still be here, but there would be no "we" to discuss it.
I am not arguing that we are important, the convrse, we evolved because of a series of accidents, and there was no inevitability about it, nor any "plan".
No worries^^. It's just that in a debate on the semantics of "random", you suddenly use another of those words which means one thing to laymen and another thing to some experts, and yet another thing to other experts (and so on). I find it funny, but understand in what way you used it.
Communication is always limited by differing definitions held by the communicator and communicatee. Even when you define terms, the definitions require words which themselves may hold differing meanings to the participants in the discussion. All you can do is look for possible instances of this etiology of miscommunication and ask for clarifications, as you did.
I am not arguing that we are important, the convrse, we evolved because of a series of accidents, and there was no inevitability about it, nor any "plan".
As I asked before: do you really think the best way to describe a function is by the nature of its inputs? Saying "evolution is random" is non-descriptive and it's inaccurate since the process works in the same way even if you remove all traces of randomness from the system.
So are you really trying to make a statement about evolution or are you just determined to ensure we all understand it's "accidental"?
Originally Posted by Fredrik
Yes it does, and why do you mention rule 30? I looked it up, and that system is obviously deterministic, but that doesn't in any way imply that evolution is.
Have you been understanding what Sol Invictus and Fredrik have been saying?
The best evidence is that quantum events are random, the particle doesn't "know" where it is either. Identical systems with identical inputs would not always give the same output.
Nonlinear systems (such as weather) are affected on a macroscopic scale by events at the quantum scale, where there is randomness. It is not merely that it is unpredicatabe because of inaccuracies in measurement, but that future random events will affect the weather.
Quote:
Mammals would have found it difficult to evolve sufficient size in the presence of dinosaurs already occupying many of the "intermediate" niches. If there are large predators, the offspring of small animals (aka dinner) will not evolve into large animals as they just become too tempting for the large carnivores. The would also have to compete against large animals already occupying the niche.
As I asked before: do you really think the best way to describe a function is by the nature of its inputs? Saying "evolution is random" is non-descriptive and it's inaccurate since the process works in the same way even if you remove all traces of randomness from the system.
If you ignore the inputs, outputs and mechanism of a process, then you don't have much left to understand.
Selection would be different if it weren't probabilistic. Evolution would be faster as beneficial traits would always prosper and deletereous traits would always vanish.
Artificial selection is faster than natural selection for that reason. The selection pressure is far closer to 100% than in natural selection, where 1% is a more realistic number.
Once you get beyond broad statements, and actually try to see what would happen in certain situations, a probabilistic treatment for selection is useful:
Consider the lemming:
Its population is cyclic. This means that if a trait occured in an individual during a population boom it is very likely that it would spread (even if it were slightly deletereous). If the same trait occured during a population crash it is highly likely that it would vanish (even if beneficial). Of course, if the trait was established in the population and was beneficial, and survived to the next population boom, it would be very likleyu to survive.
To understand the process and its implications, you need a probabilistic treatment.
The best evidence is that quantum events are random, the particle doesn't "know" where it is either. Identical systems with identical inputs would not always give the same output.
Selection would be different if it weren't probabilistic. Evolution would be faster as beneficial traits would always prosper and deletereous traits would always vanish.
Grossly wrong as I've tried to explain to you before but you just won't listen because you don't seem to get the difference between having a trait and being able to exploit it for gain - i.e. it being used.
Artificial selection is faster than natural selection for that reason. The selection pressure is far closer to 100% than in natural selection, where 1% is a more realistic number.
Yes. Very realistic numbers pulled straight from the proverbial bottom.
Its population is cyclic. This means that if a trait occured in an individual during a population boom it is very likely that it would spread (even if it were slightly deletereous). If the same trait occured during a population crash it is highly likely that it would vanish (even if beneficial). Of course, if the trait was established in the population and was beneficial, and survived to the next population boom, it would be very likleyu to survive.
To understand the process and its implications, you need a probabilistic treatment.
I see that the last 65 pages of this discussion failed to change many minds of the participants. Perhaps some lurkers were influenced. But clearly it is presumptuous of me to think I have any more to add than what was covered in those 65 pages. But then I am a presumptuous optimist, and I don't have the problem of burnout from having participated much in those 65 pages.
The more I learn about the mechanisms of genetics, the more I see a paradigm shift. That shift has not trickled down through the ranks of society just yet. We all see it arguing with the Creationists. They often argue decades old science as if we've discovered nothing new about the theory of evolution in the last 50 years.
Looking at the positions of people in this thread, I wonder if I am not seeing something similar but on a different scale. Rather than arguing decades old science, it is very much more recent. And there is no exact date because research papers written even today do not all reflect the paradigm shift that is occurring.
The research in the OP did indeed present that paradigm shift. Meadmaker did not understand my description of the article when I said,
Skep: Why do you think the research cited in the OP specifically makes that statement? Because they specifically proposed a question which answers that question. If evolution is random, X will occur. If evolution is not random, Y will occur.
Well, Y occurred.
Dave: Have you read the research cited in the OP? It doesn't make that statement.
They then reasoned that this variation, since it did not affect the final adult vulva, should have evolved in a stochastic, or random, fashion.
In executing the study, the research team analyzed more than 40 characteristics of vulva development, including cell death, cell division patterns, and related aspects of gonad development. They plotted the evolution of these traits on a new phylogenetic tree, which illustrates how species are related to one another and provides a map as to how evolutionary changes are occurring.
Their results showed an even greater number of evolutionary changes in vulva development than the researchers had expected. In addition, they found that evolutionary changes among these species were unidirectional in nearly all instances.
In other words, the researchers were very specifically looking for evidence which favored evolution as a stochastic model (random) or a deterministic model. The result supported deterministic, not random evolution.
To look at this in a different study, here is another article which actually found both random and deterministic forces involved in evolutionary changes.
the researchers suggest that the high metabolic cost of maintaining the retina is the source of selection against eyes in the cave. By contrast, no such great cost is associated with pigmentation--thus, the two traits regress for different reasons.
So what is going on? If the forces were simply random processes being acted upon by non-random natural selection, then there shouldn't have been any difference in the findings in the cave fish study.
But there was a difference. And this is what I mean about a paradigm shift in evolution theory. We have mostly all agreed there are random and nonrandom processes. I think nonrandom describes the process better, Mead thinks the two should be looked at more equally, and mijo thinks random describes the process better. (Forgive me Dave if I am misreading you.)
This minireview will describe mechanisms of mutation that are not random and can accelerate the process of evolution in specific directions. The existence of such mechanisms has been predicted by mathematicians (6) who argue that, if every mutation were really random and had to be tested against the environment for selection or rejection, there would not have been enough time to evolve the extremely complex biochemical networks and regulatory mechanisms found in organisms today.
Taken together, the DNA sequences of these primates suggest a model whereby highly repeated DNAs are established and evolve as a consequence of unequal nonrandom exchanges of DNA duplexes. These exchanges may be mediated by short repeated nucleotide sequences and involve exchanges within and between the greater than 170-base-pair wings.
There are studies seeking to test the random/nonrandom hypotheses specifically, like the articles I linked to above and the article from the OP. Researchers are looking at the mechanisms for non-random evolutionary processes at the supposedly random genetic level.
There is a random component in evolution. No one is arguing there isn't. But there is a paradigm shift in how genetic mutation is actually directed that has only recently been added to the theory of evolution.
Actually, I have addressed the views with which I disagree. You just don't like my responses, because they are not of the form: "Oh, now I see the light. Of course evolution by natural selection is non-random. I admit that saying that saying that evolution by natural selection is random is a stupid and deliberately confusing creationist straw man. Thank you, skeptigirl, for your clear explanation and presentation of copious evidence."
Is there any evidence that I could present to convince that evolution by natural selection is random by the nontrivial definition "[o]f or relating to a type of circumstance or event that is described by a probability distribution"?
Is there any evidence that I could present to convince that evolution by natural selection is random by the nontrivial definition "[o]f or relating to a type of circumstance or event that is described by a probability distribution"?
Do you ever check your citations to see if they are claiming that evolution by natural selection is not random because it is biased to a certain outcome?
This is the reason the article in the OP said evolution by natural selection is deterministic and the reason why I disagree with the statement in the article that it is deterministic. Such a definition of random is inconsistent with the vast majority of phenomena that we describe with random variables and probability distributions, therefore causing a strange, confusing, and contradictory notion of a deterministic random variable. The only truly consistent and rigorous definition is "[o]f or relating to a type of circumstance or event that is described by a probability distribution" because each of the key terms (i.e., "event" and "probability distribution") is defined in a very specific and unambiguous way in probability theory, a fact that you would know if you bothered to pick and scan any probability theory textbook.
But the problem is that the actual research did not say "Evolution is random", or even "Evolution is stochastic." They were looking specifically at developmental systems drift. There has been a debate going on within the biological community about how traits change. Specifically, the role of "genetic drift".
"Genetic drift" refers to evolution (i.e. genotype and phenotype changes in a population) in the absence of selection pressure.
Biologists noted change in species over time, with no obvious advantage for the species as a result of that change. Why did that happen? Some people said that these changes occurred because there was some unrecognized selection pressure. Without that pressure, there would be a conservative force that would keep the population stable. Others reasoned that with no selection pressure, there might be random changes in the population to a trait that was no better, but no worse, than the previous state.
The biologists from the OP figured out a way to test the two theories. These nematodes gave them a way to track the changes. If the changes in the population were random, not the result of selection, the traits involved would go sometimes this way and sometimes that way, and sometimes reverse direction, because there was no real advantage for one direction or the other. If the changes provided an advantage, the direction of change would be consistent, as things got a little bit better at each step.
It turns out that most, but not all, of those changes went in a single direction. Developmental systems drift occurs primarily as a result of selection pressure.
So does that mean that "evolution is not random?" Well, again, you have to define your terms. In their case, they defined random as not favoring one direction or the other for development of a particular trait. They defined evolution as changes to a trait. Using those terms, "evolution" is not "random". (And actually, they never used the word random, and they never claimed to define evolution. They said stochastic, and they specified evolution of a trait.)
I'm not sure that this is a real paradigm shift at all. I think it's a return to a paradigm that is as old as Darwin. It did challenge a potential new paradigm that said there were other forces besides natural selection that were responsible for changing species' characteristics. This paper says that "genetic drift" is not a significant role.
(Aside: We speak of "natural selection" as a "force" or say it "drives" evolution. We can't help ourselves. We have to talk about causes, and things that do things, but it is an illusion. Natural selection isn't a force, it's a consequence.)
Mead thinks the two should be looked at more equally, and mijo thinks random describes the process better. (Forgive me Dave if I am misreading you.)
More accurately, I think the two should be given different weight depending on what you are describing. Either can lead to misunderstanding of the process. I think insistence on saying that one or the other is "better" either means you are fixated on one aspect, or there's some sort of psychological or ideological bias against the other.
But the point is that nothing can be "constrained and biased to the point of deterministic". If there is at least one other possible outcome, even if it has a probability of 0, the system is "stochastic" or "random". "Stochastic", or, to a lesser extent, "random", is truly the most rigorous term that can be used to describe, and all the obfuscating and equivocating that articulett attempts will not make that false.
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