Information Theory Places New Limits On Origin of Life 211
KentuckyFC writes:
Most research into the origin of life focuses on the messy business of chemistry, on the nature of self-replicating molecules and on the behavior of autocatalytic reactions. Now one theorist says the properties of information also place important limits on how life must have evolved, without getting bogged down in the biochemical details. The new approach uses information theory to highlight a key property that distinguishes living from non-living systems: their ability to store information and replicate it almost indefinitely. A measure of this how much these systems differ from a state of maximum entropy or thermodynamic equilibrium. The new approach is to create a mathematical model of these informational differences and use it to make predictions about how likely it is to find self-replicating molecules in an artificial life system called Avida. And interestingly, the predictions closely match what researchers have found in practice. The bottom line is that according to information theory, environments favorable to life are unlikely to be unusual.
Thermodynamic equilibrium is not required (Score:2, Insightful)
It's a fallacy that entropy always increases ON EARTH, and therefore life is impossible to have evolved naturally, because it violates the 2nd law of thermodynamics. That's only true in a closed system, which most definitely the Earth is not. There's this "Sun" bombarding the planet with energy, constantly.
Stop bringing thermodynamics into biochemical or origin of life questions. It's irrelevant.
Re:Thermodynamic equilibrium is not required (Score:4, Informative)
The key idea in Adami’s formulation is that living systems do not exist in a state of thermodynamic equilibrium
Not only is it not required, they're looking for exactly the thing you're mentioning, so I don't see any point in your comment. Also, they're not saying anything about Earth with increasing entropy. Where did you get that? Are we reading the same things in the first place?
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Pumping energy into a system does not necessarily the order of things.
Also even though the article also mentions therodynamics, shouldn't it be the information theory entropy that is used here?
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The thermodynamic and information theory definition of entropy are the same, which is why "bringing thermodynamics into biochemical or origin of life questions" is entirely relevant.
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The definition is the same, but not the application.
Instead of looking at the state of order in the system, the article seems to be more interested in the transfer of information. That's what I read from their definition of what life is.
The definition of life? (Score:5, Interesting)
If we define life as the ability to organize and propopagate information then the highest form of life is a salt crystal or any self propagating organization of atoms with long range order. A diamond has far lower entropy than any living system. Like wise if we define it as system that processes energy to propogate itself then we have Fire as the ultimate for of life.
clearly gasses (disorded are dead) and crystals are dead. SO is life a liquid (in the middle of the two)? Again obviously not.
The best definition of a living system in terms of information tehory concepts I have come across is the one by David Wolpert who coined in the term self-dissimilarity in reaction to the vogue study of self-similarity in self-organizing systems. For example, a pile of sand is self-organizing system that is ever changing but also ever-self simmilar. it's not alive either
so solids, liquids, gasses and self-simmilar self organizing systems are all bankrupt as a informational definition of life. What's self-dissimilarity then?
It's the concept that the organizational principles of a system can suddenly change as one crosses scales.
imagine one zooms out from a microsope from the atomic scale. at first you see the atom and it has some interesting symmetires in the way the electron oribits have some simmilarities. at a higher scale we see the molecule. then the collection of molecules. soon we see the patterning of molecules.
we observe that this is infact cell. then many cells. then it's an organ. then its many organs. then an animal. then a school of fish. then zooming our we see schools of fish separated across the ocean.
the key insight is this. at each scale everything you infer about the information content and predictibitly of adjaceny in the pattern works to predict the patterns propoagation at a slightly larger zoom. Up until it suddenly fails. you reach the edge of the liver or the edge of the cell or the edge of the animal. then the lower scale is useless in predicting how the next scale up is organized.
these abrupt steps in dissimilarity is a halmark of living systems. the degree of information gain at the step is phenomenal. this is different than saying for example that a composite rock is alive. the difference is that the system is processing information and energy across these organizational boundaries. that's pretty much the best definition of life interms of a single defintion that can be plotted on a graph. the x-axis is the zoom, and the y-axis is the predictability of the next larger scale from the lower one. you see steps. that plus the processing of information across steps is a living system. If you accept this you might feel like their are non-traditional defintiions of life as well. for example, if a bacteria is living thing, is it possible that a community of bacteria is also a lvifing thing. Perhaps the earth is too.
What's intriguing here is that systems with this property may imprint themselves on other systems. you might for example be able to spot radio emissions or atmospheric molecular composition that displays the imprint of dissimilar steps in it's self organization.
SO unless this theory considers this, I'm skeptical about it. Salt is self organizing but it's not alive. It is however highly probable. Indeed eutectic separation is highly propable but it's just physics not life.
Re:The definition of life? (Score:5, Interesting)
Since I seem to be dismissing that paper for trying to use thermodynamics to define the probability of a living system I wanted to quickly add that I am explicitly not dismission it. I'm dismissing the summary that conflating the definition of life with a lower bound on it's thermodynamic probability. Often times thermodynamic bounds are very useful in ruling out how something did not happen and to identify the high probability way something could have happened.
Take for example, the observation that most complex living systems are beautiful as well. Why are they beautiful to us. I think it is because they visually have organization. And the single most obvious facet of organization are symmetries at large scale. For example, atomically speaking your eyes are very far apart. Yet your body has this beautiful bilateral symmetry.
THe obvious question is whether symmetries in living systems occur because living systems select for symmetry because there is an evolutionary advantage to it or because of thermodynamics.
to see this take something simpler. The packing of seeds in a sunflower is optimal in some sense (fibonaci) yet one might believe there's a chance it's just a thermodynamic accident not a careful selection.
In fact drill down a little more and consider the fact that nearly all proteins in your body form homo dimers that are symmetric.
an interesting paper
http://www.ncbi.nlm.nih.gov/pu... [nih.gov]
comes to the stunning conclusion that this symmetry is not from evolutionary selection! it's overwhelmingly improbable that function can arise from random collisions between proteins, and the only likely way two proteins can collide and form a low energy conformation that last long enough to perform a function is for collisions that form a symmetrical arrangement. Almost all other collisions wont last long enough for the dimer to perform a function (such as catalyzing production of a useful metabolite). Since Natural selection cannot operate on anything that doesn't do something to increase fitness this means that assymetric collisions are completely invisible to the organism. Therefore thermodynmics can rightfully claim that nearly all protein symmetry arrises simply from thermodynamic probability not from natural selection having a prefernce for symmetry. This is not to say that symmetry has no selectable characteristics. It's just that at the molecular level, those selectable characteristics are not required to explain the emergence of symmetry as we observe it. The frequency that we observe symmetric versus asymmetric homo dimers of proteins is exactly the frequency we would expect at random due to thermodynamics.
Thus the interesting thing about this new work in thermodynamics is it sets a lower bound on the conditions needed for life to emerge. It does not however define the probability of life emerging.
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Even starting with you assumption, life is much more complex and it seems to me has much lower entropy than any diamond.
You are making my point for me. The only reason you beleive life is more complex than a diamond is because of the complexity of it's many different kinds of organization. a diamond is a very simple organization based on a single organizing principle. (and so I might add is DNA oligomerization which is what the author of the paper is discussing). But a living cell has many different kinds of organization whos infomration partioning and propagation seems very non-random.
and yet the diamond has lower entro
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There's this "Sun" bombarding the planet with energy, constantly.
Then take the two-body system given by the Earth and the Sun as the closed system.
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But they aren't.
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What about the tons of dust and debris that fall to Earth every single day? What about the heat this planet radiates out, the loss of gases that occur naturally?
We do not have a closed system. Period. You can be ignorant and attempt to argue it all you want, but you will always be wrong.
Always.
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You can be ignorant and attempt to argue it all you want, but you will always be wrong.
But:
progress in science consists in replacing a theory that is wrong with one that is more subtly wrong -- unknown
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There's this "Sun" bombarding the planet with energy, constantly.
Then take the two-body system given by the Earth and the Sun as the closed system.
If it was a closed system the Earth would have cooked by now coming to equilibrium with the Sun - fortunately we have the cold bath of the rest of the universe to which most of the Sun's energy flows, as well as some heat from the night side of the Earth - so it is not a closed system.
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It's a fallacy that entropy always increases ON EARTH, and therefore life is impossible to have evolved naturally, because it violates the 2nd law of thermodynamics. That's only true in a closed system, which most definitely the Earth is not. There's this "Sun" bombarding the planet with energy, constantly.
Stop bringing thermodynamics into biochemical or origin of life questions. It's irrelevant.
Yes energy is constantly added but without a system to use it it only increases entropy think uv radiation and Dna the energy there disorders the system rather than maintains it.
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You're right but isn't all this just extremely banal? To say that entropy is a statistical measure of disorder and that between certain bounds, life is more or less likely is simply to say that a body at equilibrium (like Mars) is much less likely to harbour life than one that isn't (like the Earth). It's a "no-shit Sherlock" moment.
What I took from TFA is not that there's anything groundbreaking in terms of prediction in the paper, rather it provides some minor mathematical grounding for our theories of abiogenesis [wikipedia.org]. No, it's not a huge breakthrough, and no it doesn't provide any definitive answers. What it does is lend credence to the idea that abiogenesis is fairly common, given appropriate conditions.
Does this change the world? No. Does this add (in a minor way) to our theories of how life could begin? Yes.
Unusual in a huge system ... (Score:2, Insightful)
Except in a universe with billions and billions of galaxies, each containing billions and billions of stars ... some of us assume that, statistically, the 'unusual' happens all the time.
In the last 30 years our understanding of how many stars have planets has changed entirely. We used to think there would be a small amount with planets and that we were really unique. Now, not so much.
These co
Re:Unusual in a huge system ... (Score:4, Informative)
Wait. If they are unlikely to be unusual, then they are likely to be usual. Right ?
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Oh, shit ... yes, I'm a moron ... I got the opposite out of that.
So, information theory tells us life should be common.
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Sounds pretty unlikely to me. ;-)
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It isn't not an entirely unreasonably way to discuss the opposite.
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the law of astronomically (no pun in tended) large numbers.
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'unlikely to be unusual' is a weird way to put it.
I understand that to be the same as 'likely to be usual', or as one would normally say: 'likely'.
So environments favorable to life are likely?
You mean fewer people should not read them... (Score:2)
Re: Unusual in a huge system ... (Score:2)
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The universe is infinite, thus every unusual thing that can happen is also infinite, just a smaller infinite.
If we assume particles have a finite ways to be arrange(as it seems) that means there are a small infinite places just like earth, with another you reading the exact same post by another me.
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Here, let me fix that for you:
There ya go. We don't actually know if the universe is infinite or not. We do know the Universe is Euclidean, my layman's understanding of that concludes that we live in one of two universes:
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Sorry, but that is a fallacy. You can very easily have things so unlikely that this universe will not have any instance or only one of them. This happens especially often if you do not know the probability of things.
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We used to think there would be a small amount with planets and that we were really unique. Now, not so much.
I'm not sure we ever really believed that. Now we just have proof.
I think a lot of us expected extra solar planets to be common, and that even extra-terrestrial life will prove to be fairly common. But for me, at least, the open questions are how common higher life forms are, and whether 'sentience' is a common evolutionary solution... or relatively rare / unique...
Symmetry? (Score:2)
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indeed:
http://www.ncbi.nlm.nih.gov/pu... [nih.gov]
Life may be common, but not always as we know it (Score:3)
One interesting thing about this is that if we were to find a planet filled with plants made up of D amino acids and left-handed DNA we may find ourselves unable to consume those plants for nutritional value.
Re:Life may be common, but not always as we know i (Score:5, Funny)
....if we were to find a planet filled with plants made up of D amino acids and left-handed DNA we may find ourselves unable to consume those plants for nutritional value.
More importantly, they would not be able to consume us for nutritional value.
Re:Life may be common, but not always as we know i (Score:4, Insightful)
So, we'd be junk food?
Great, that makes me feel much better. :-P
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Plants might not be intelligent enough to realize that until too late (for us).
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or they will taste like peppermint. :)
Too esoteric?
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or they will taste like chicken. :)
Too esoteric?
There. FTFY.
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not able to sustain both directions
But either direction may have turned out to be viable. So at this decision node, the probability of life would be 1. On the other hand, given an initial equal distribution of forms, had one been non viable, the other would have out-competed it.
What we need to look for is what the probability of local maxima or dead ends is. Where some process is preferred at that point and is selected. But for which more advanced branches do not exist.
What? (Score:5, Funny)
environments favorable to life are unlikely to be unusual.
How can you not argue against not having that be untrue?
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Because previously it was said:
"environments favorable to life are likely to be unusual."
now they know it's unlikely to be unusual
The web of life... (Score:3)
I blew my wife's mind the other day when I pointed out that we are literally just a small component of a single, globe-spanning, four billion year long chemical reaction. A single, very long running checmial reaction. It's pretty neat when you think about it.
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I blew my wife's mind the other day
Did you mean to post AC? This is admissible in court, you know.
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I blew my wife's mind the other day when I pointed out that we are literally just a small component of a single, globe-spanning, four billion year long chemical reaction. A single, very long running checmial reaction. It's pretty neat when you think about it.
Yep. I've often pointed out that life is like a fire that has the ability to gather its own wood. Ultimately, that's what we are - not a fire per se but a well-controlled chemical reaction.
in other words... (Score:4, Interesting)
Re:in other words... (Score:5, Interesting)
Nonsense.
The argument seems to be that, because we don't see "evidence of technological activity" when we look out at the universe, intelligence leading to technological culture must be rare or absent. If an entity or a culture doesn't cause huge, recognizable perturbations in its environment, it must not represent "intelligence".
Think of an electrical engineer from the 1880s studying the data cables that run through a modern city. He might cut into a cable, expecting to find a wire carrying electrical impulses. Instead, he sees a bundle of glass fibers, glowing brightly if he nicks or breaks them. No tools at his disposal would let him even detect the gigahertz-scale fluctuations in that light.
For that matter, consider a 1960s "exobiologist" trying to decode an intercepted 2014 video stream. If you told him it was image data, he might look for periodicities that would let him determine rows, columns, and pixels. In an MPEG-compressed stream, he wouldn't get far. Heaven help him if it's DRMed.
My point: the things we look for as evidence of technological civilization may just be evidence of insufficiently advanced technological civilization. The "filters" we fear -- nuclear annihilation, bioterror, grey goo -- may indeed claim a lot of civilizations, or they may be laughably uncommon. It seems to me most likely that, instead of trying and failing to build space-opera-scope interstellar empires, most civilizations simply grow into something that we aren't yet sophisticated enough to notice.
More Complicated Than That (Score:3)
a key property that distinguishes living from non-living systems: their ability to store information and replicate it almost indefinitely.
As Douglas Hofstadter pointed out, it's actually more complicated than merely indefinite replication. It has to allow variance while still retaining the ability to replicate. Sure, there are clones everywhere, especially outside the animal kingdom, and they still considered "living". So the quote is still technically true. But it doesn't capture how immensely more difficult it was for life we observe here on Earth to come about. It also raises an interesting question. Did non-varying life have to come about first, in order to saturate the environment with organic compounds? Did the varying life then come about later, piggy-backing on this enriched environment? Or can you go straight from an abiotic world to varying life?
a prediction of not the future (Score:2)
"The new approach is to create a mathematical model ... And interestingly, the predictions closely match what researchers have found in practice"
Unless the mathematical model was built *before* any of those practical empirical test results, it is not at all interesting or surprising that the model happens to match the pre-existing data.
Related work: entropic bounds on (Score:2)
Related work:
http://arxiv.org/abs/1209.1179 [arxiv.org]
surprisingly no references between Adami and England.
"Self-replication is a capacity common to every species of living thing, and simple physical intuition dictates that such a process must invariably be fueled by the production of entropy. Here, we undertake to make this intuition rigorous and quantitative by deriving a lower bound for the amount of heat that is produced during a process of self-replication in a system coupled to a thermal bath. We find that the m
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And this [ggpht.com] is the only information that you need.
Re: First (Score:2)
Re:Empirical Data Trumps Information Theory (Score:5, Insightful)
Gibbs Free Energy (Score:3)
Meh. Information is basically tied to entropy. You can reduce entropy (which is to say, you can order information); it just takes energy to do so (and in the process releasing waste heat).
So, basically, this says nothing more useful than "Life requires a source of free energy, and a way to reject waste heat."
Sure, but we knew that already.
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No, it puts quantitative limits on what is to be expected. That's quite different from your qualitative results which we know.
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No, it puts quantitative limits on what is to be expected.
Delta G = Delta H - T Delta S
where S = k ln (omega)
Any other quesitons?
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What do you think a tornado is?
The finger of God. However you have a good point. Matter spontaneously organises itself in order to reach maximum entropy in minimum time, Brian Cox has done an excellent documentary series about this stuff. At first glance life ( and tornadoes ) appear to go against the laws of thermodynamics by making itself more organised but such observations (often made by creationists) ignore the rate of increase in entropy of the system as a whole. Like tornadoes, life will spontaneously arise where there is an energ
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Where is the waste heat, or change in internal energy, in a magnifying glass system, used to focus the sun's rays to produce a concentrated, high-temperature Airy disk?
U = Q - W
The U (internal energy) of a magnifying glass does not change appreciably during use. Q is heat added to the system; it is much less than the W, or heat produced by the focused rays, which do the work of lighting a fire.
U is small, Q is small, W is large. In theory, U should be large and negative. But it's not...
http://www.askamathem [askamathematician.com]
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With your magnifying glass example, there's nothing that says you can't change the entropy of the energy passing through it at the cost of... the energy passing through it. There is a cost though, and that is the diffraction index of the glass that is doing the focusing. It absolutely does heat up. It's highly efficient (doesn't heat up much, assuming a good diffraction index), but it's there. If you were trying to imply that Q is the energy added
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"If you were trying to imply that Q is the energy added to the system that the light is being focused upon,"
No, I'm guessing Q would be the heat added to the magnifying glass on the sun side, which is very small compared to the heat produced on the side where the light is focused; the latter heat does the work you want (lighting a fire or whatever). Since Q is small, and W is large, U should be negative. But it's not.
"The process of compressing your data costs more than decompressing it. Rule of thumb holds
Re:Gibbs Free Energy (Score:5, Informative)
Costs more in what sense? Energy cost? Lines of code cost? Time cost? In any event, it is not something that I consider when zipping a file. Zip and unzip are treated as equivalent from the user's standpoint.
The great thing about the universe (and information theory) is that it's flexible in how the cost be paid, but the laws of thermodynamics apply all the way down the chain. Zipping can cost more in memory, or more in CPU cycles. The fact that it's the same to you doesn't really matter. It's not the same to the things doing the work.
The point that confuses me is: the energy on the outside lens surface can't light a fire, but the energy produced by the glass can.
The energy hitting the outside of the glass *can* light a fire. It's simply spread over too wide of an area. In the same way that all the potential energy in the gap between the clouds and the ground doesn't immediately kill you, as it exists at all times. It requires a mechanism to focus it before it becomes fatal. The poles are cooler than the equator not because there is less sunlight passing through a square meter of space above them as opposed to the equator, but because the earth sits at a less perpendicular angle to that light, so it is spread out over more area.
You can simulate this effect by angling your magnifying glass in such a way as the focused dot obliquely hits the object-to-be-burned enough to spread out the energy again (let entropy do its thing)
How is the lens doing any work, in that sense?
The lens is doing work via diffraction. Light can't just be redirected by anything but the curvature of space. While that lens looks transparent, what is actually happening is the light is being aborbed by every atom (or electron, more precisely) it hits, and then re-emitted as an all-new photon with a change of direction that follows a statistical set of rules that focuses it (based on the diffraction qualities of the lens). The absorption and re-emission has a cost, it's not free.
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What cost does the absorption and re-emission extract from me, every time I use the lens to do the work I want it to do? What am I losing, what am I giving up to get heat of ignition from sunlight?
I had to buy the glass, and there was an energy cost in producing it. But those are one-time expenditures. Once it's made, the cost to light a fire is nothing.
Also, the first law of thermodynamics seems to be violated, as outlined above. U = Q - W. U (internal energy of the system, in this case the magnifying glas
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Zipping a file takes energy to power the CPU. Unzipping does too. In both cases, global entropy has been increased.
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What about information entropy? The entropy is lowered when the file is zipped, then raised when the file is unzipped. According to the "rule of thumb" cited above, if a process is reversible, the entropy remains constant. Zipping is reversible, but the information entropy is not constant; it lowers and increases.
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Fail. The level of confidence in Quantum Theory describing physical reality is pretty well established, but it is both incomplete and not absolute truth. Information theory, on the other hand, does not apply to reality unless you grossly simplify, hence it is actually impossible for anything real to "violate" it, it is just not close enough to reality.
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Information does travel through space at a velocity faster than c - see the EPR paradox, which was subsequently questioned by Bell, and then experimentally tested by Alan Aspect (sorry I don't know the correct French spelling for his name).
Based on the evidence, quantum information does seem to travel faster than c.
Given the paradox of the wave-function collapse within the Copenhagen interpretation of QM (once a particle is measured it takes on a definite set of properties, which means that the wave-functio
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Information does travel through space at a velocity faster than c - see the EPR paradox, which was subsequently questioned by Bell, and then experimentally tested by Alan Aspect (sorry I don't know the correct French spelling for his name).
Based on the evidence, quantum information does seem to travel faster than c.
Given the paradox of the wave-function collapse within the Copenhagen interpretation of QM (once a particle is measured it takes on a definite set of properties, which means that the wave-function must collapse everywhere simultaneously) it suggests that quantum information is transfered instantaneously.
This most probably shows that the wave-function-collapse interpretation does not have much to do with the reality and is just an artifact of the theory. There are other interpretations which do not involve such mysterious collapses and provide smooth transition from quantum to macroscopic level. The logically most consistent one is the many-worlds interpretation (http://en.wikipedia.org/wiki/Many-worlds_interpretation).
Re:Empirical Data Trumps Information Theory (Score:4, Insightful)
This is not information theory or quantum theory, this is Information Theory and Quantum Theory. It is astonishing that there are still people around that do not understand the difference and claim they are "just theories". No. They are not. Apparently the educational system is far worse then generally assumed.
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the educational system is far worse then generally assumed.
Yep. The education system even fails to teach spelling.
(Sorry, I just couldn't resist. ;)
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There are no misspelled words in the quoted excerpt. The error is improper use of the word "then" versus the presumptively intended word "than," and thus the mistake is classified as a grammatical error.
Sorry, I just couldn't resist.
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In light of past attitudes, would it not be more informative to say "environments favorable to life are unusually likely"?
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The phrase "...places new limits on..." suggests that they have found that Life is even less likely. But the phrase, "...favorable to life are unlikely to be unusual...", however awkwardly, suggests that Life is more likely.
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Many people have an emotional need for the presumed eternal correctness of "a law of science", even though no such thing can exist. And they are incompetent to rate the relative stability of various different theories.
Well, everyone is incompetent to rate the relative stability of various different theories except, perhaps, in their own small area of expertise. That's why we are forced to depend on experts. Then we need to decide how much to trust each expert. It's not a simple problem, and it's probabl
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All models are flawed, by definition. These holy "Theories" you have such emotional attachments to simply use models. In a 100 years, they will be superseded and allow us to do things we can't think of today. Like GPS wouldn't work if we relied on Newton's theory of gravity.
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There's a difference between the colloquial use of the word "theory" and the scientific use, which many people don't understand. In the colloquial use, "theory" means "hypothesis," so that the layman becomes confused when it's used in science. Hence expressions like, "only a theory." Even educated people will use expressions like, "Gravity is only a theory," as if that explained anything.
But this is how language works. Meanings shift through use (or misuse) over time. Think of how the word "addiction" is no
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More, any particular god is a hypothesis. It doesn't rise to the level of a theory until you can use it to make verifiable predictions that are then tested.
FWIW, there are several gods that I have tested, some of them gave weakly positive results. None of them matched the gods of any standard religion, which religions have so defined their gods that emperical tests are impossible.
N.B.: This does not prove that they are incorrect, it proves that there is no reasonable way to chose between them, and the nu
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If it's unlikely that life can appear I think it's even more unlikely that intelligent life can occur.
I once did put what I thought was plausible figures into the Drake equation [wikipedia.org] and ended up with a value of about 0.8.
Mostly because I think that the chance of an intelligent civilization is low. I find it much more likely for life to appear and spread in a galaxy than for intelligent life to appear that is able to develop technology.
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Considering our planet only has another billion years before its turned into a crispy planet like Venus (killing all life in the process) due to our sun exhausting its hydrogen supply, it seems even less likely that intelligent life which can spread beyond its planet would have time to evolve.
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Actually it will be a lot worse than Venus and due to a different cause in that the sun would actually be irradating many times more energy on it, and possibly even engulfing it in hot plasma. Venus is heated by the insulation of a huge amount of CO2, the Earth with that much CO2 would be equally hot, and Venus without it would be just a tropical Earth. And when the sun expands the CO2 will be irrelevant (I would think the heat would actually make it escape to space), not that that is going to help any.
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The sun might have 5 billion years left in it, but it will swell and render the earth uninhabitable in only 1 billion. Given that it took 1.5 billion years for life to form on earth at all, and another 3 billion after that to turn into something intelligent, the window (from our single data point) seems rather tight. A little setback here or there, an ill-timed asteroid impact (or lack of a well-timed impact) and you've got nothing.
Hot stuff (Score:2)
Except that our sun isn't the most common type of star in the universe. IANAA (Astronomer), but I recall hearing (possibly from the New Cosmos series) that dwarf stars are far more common than G type stars. Since they put out a constant volume of energy for a very, very long time, this would give life plenty of time to evolve into intelligent lifeforms. The more massive a star, the shorter a window of time for life to evolve near it, so it wo
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That's a good point. My brain was not working...I clearly need more coffee.
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There is water on the moon, and mars.
Gravity is real, ok !
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unless you put it in a recurring cron job it's not alive
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Here's a few choice quotes:
Although now rejected by mainstream science, vitalism has a long history...
Vitalism is no longer philosophically and scientifically viable...
By 1931, "Biologists have almost unanimously abandoned vitalism as an acknowledged belief."