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History has proved time and again that mathematical modelling is no substitute for a telescope (or other data collection device). Nonetheless, some theoreticians have recently put forward a statistical analysis which suggests that life is probably very rare in the universe – despite the apparent prevalence of habitable-zone exoplanets, being found by the Kepler mission and other exoplanet search techniques.
You would be right to be skeptical, given the Bayesian analysis undertaken is based on our singular experience of abiogenesis – being the origin of life from non-life, here on Earth. Indeed, the seemingly rapid abiogenesis that occurred on Earth soon after its formation is suggested to be the clinching proof that abiogenesis on habitable-zone exoplanets must be rare. Hmm…
Bayes theorem provides a basis for estimating the likelihood that a prior assumption or hypothesis (e.g. that abiogenesis is common on habitable-zone exoplanets) is correct, using whatever evidence is available. Its usage is nicely demonstrated in solving the Monty Hall problem.
Go here for the detail, but in a nutshell:
There are three doors, one with a car behind it and the other two have goats. You announce which door you will pick – knowing that it carries a 1/3 probability of hiding the car. Then Monty Hall, who knows where the car is, opens another door to reveal a goat. So, now you know that door always had a zero probability of hiding the car. So, the likelihood of the remaining door hiding the car carries the remaining 2/3 probability of the system, since there was always an absolute 1/1 probability that the car was behind one of the three doors. So, it makes more sense for you to open that remaining door, instead of the first one you picked.
In this story, Monty Hall opening the door with a goat represents new data. It doesn’t allow you to definitively determine where the car is, but it does allow you to recalculate the likelihood that your prior hypothesis (that the car is behind the first door you picked) is correct.
Applying Bayesian analysis to the problem of abiogenesis on habitable-zone exoplanets is a bit of a stretch. Speigel and Turner argue that the evidence we have available to us – that life began quite soon after the Earth became habitable – contributes nothing to estimating the likelihood that life arises routinely on habitable-zone exoplanets.
They remind us that we need to acknowledge the anthropic nature of the observation we are making. We are here after 3.5 billion years of evolution – which has given us the capacity to gather together the evidence that life began here 3.5 billion years ago, shortly after the Earth first became habitable. But that is only because this is how things unfolded here on Earth. In the absence of more data, the apparent rapidity of abiogenesis here on Earth could just be a fluke.
This is a fair point, but a largely philosophical one. It informs the subsequent six pages of Spiegel and Turner’s Bayesian analysis, but it is not a conclusion of that analysis.
The authors seek to remind us that interviewing one person and finding that she or he likes baked beans does not allow us to conclude that all people like baked beans. Yes agree, but that’s just statistics – it’s not really Bayesian statistics.
If we are ever able to closely study an exoplanet that has been in a habitable state for 3.5 billion years and discover that either it has life, or that it does not – that will be equivalent to Monty Hall opening another door.
But for now, we might just be a fluke… or we might not be. What we need is more data.
Further reading: Spiegel and Turner. Life might be rare despite its early emergence on Earth: a Bayesian analysis of the probability of abiogenesis.
What a fantastic article! Well done!
Great article. Even so, scientists and science writers who make these estimates are well-aware of the anthropic bias, even if they don’t mention it in their article (which they really should do, especially if writing for the general public). I definitely agree that life’s arising so soon on Earth may be due to chance. For evidence backing up the claim that life need not arise SOON after it’s host world formed, look to Titan and the ever-brightening sun in combination. We also commit anthropic bias when we assume life can only survive at temperatures and “Watts per meter squared” of sunlight similar to our own. There may be lifeforms that live at higher or lower temperatures than ours, although I still believe that H2O / Carbon life is the most likely in the universe due to the sheer ubiquity of the two substances and their apparent ease of interaction with each other and other elements where it concerns life’s creation.
While I agree that carbon life is the most likely, I’m intrigued by the possibility of life ‘not as we know it’. Biological ‘life’ is a complex system that hosts sentience. While this may be philosophical supposition, if non anthropocentric sentience ‘could’ exist’ in almost any complex system, then its rational to suppose that life ‘not as we know it’ may be all around us. As a hypothetical, our solar system is a dynamic complex system, if we took a great leap of the imagination and supposed that it could be sentient, how could we possibly ever hope to quantify that level of difference between our notion of existence.
In another hypothetical example; I wonder if the microbial gut flora in our stomachs, if it was sentient, would ever consider that its host might also be sentient? I realize this is a definition of anthropocentric bias but it highlights some pertinent questions, the most interesting of which is, how would we hope to communicate or even recognize sentience that exists at differing scales of existence.
Fun Sunday musing. 🙂
The problem with sentience is that it is a poorly defined term. The Oxford dictionary states that sentience is the ability to “perceive or feel things.” Pretty much all complex life on Earth covers either of these two abilities; necessitated by sensory perception. Here the line becomes blurred as you scale down to ever more primitive forms of life.
The second area of thought you bring up is less sentience as it is intelligence. The problem with the intelligence debate is that it gives rise to speciesism. Which species are intelligent? Gut flora may not be capable of metacognition, but Dolphins appear to be. Where do you draw the line? How do you know for certain a species isn’t intelligent?
When they vote for a Republican candidate who believes in Intelligent Design!
eeek!
Those Republican candidates might almost be welcome when measured against the Creationism nutters that are attempting to take over America.
@William Sparrow,
I know you are aware there is relatively no distinction between intelligent design and the creationism crowd — you are just having us on, aren’t you?
Mary
The Dolphin brain is larger and actually more complex than a human brain. They clearly have a rich or extensive subjective inner conscious existence. The problem is as a species they will never reach the stone age. A similar species on some planet 1000lyr away will never be detected by us. If they send a radio signal or use some device to send some signal encrypted in a universal system (Golay codes, Mathieu groups etc) then we can conclude the presence of an ETI.
LC
So Long, and Thanks for All the Fish.
Agreed and agreed, I guess if we could distill this notion down to a more manageable level and say we did discover some form of life that exists on our boundary of existence in time and space. Could we ever hope to communicate with them. ?
The dolphin is a great example, we agree that they are sentient in the oxford dictionary sense, and self aware. But our attempts at communication with them have not been very productive. Without something like mathematics as a mediator for intelligence differing species are going to have a very hard time trying to communicate. But its not just the applicable language mediator that is needed. We need to consider the differing senses used for communication.
Dolphins have been recently proven to use Electro reception as a sensory tool, Electro-communication may be possible, if we can work it out it may be the first inter-species dialogue we have ever encountered.
http://en.wikipedia.org/wiki/Electroreception
Actually we’ve known that Dolphins use echolocation for decades.
Not ‘Echo -Location’; Electro- Reception…
Its quite possible they also communicate using this sense.
http://www.livescience.com/15240-dolphins-sense-electric-fields.html
This I think hits at the core of what makes our search so frustrating. Even if a species is intelligent, it may never have developed dexterous appendages. It was our ability to manipulate our environment which put us on the road to rockets.
Here we have what could very well be two highly developed intelligences on one world. Not only can we barely communicate with one another – it’s taken us centuries to even realize the other may in fact be intelligent.
I’ve read stories from researchers in the field of Dolphin intelligence and they claim that their Dolphin subjects are equally frustrated at our inability to communicate! It’s as if we might as well be on separate planets.
Perhaps solving the Dolphin communication barrier is a good trial exercise if we plan on communicating with ETIs. After all, it is very possible we might run into other Dolphin-like creatures on distant worlds.
Notes:
The Ancient Greeks had a law that equated the slaughter of a dolphin with the same punishment for murdering a Greek citizen.
Agreed. These points are the reasons I initially became interested in dolphins…and is the basis of my handle.
If I remember correctly, David Brin once made the point that it could be that intelligence is fairly common in the Universe, but that the majority of it could be cetacean/octopi/squid-like in that they may be *physically* incapable of the necessary technology. No matter how intelligent, dolphins on their own will never create radiotelescopes or starships. Intelligences like those will be found only by those intelligences (hopefully not limited to ourselves) that have the capacity to personally go whereever they are, and/or send probes which, speed-of-light communications being what they seem to be, would have to be significant AIs themselves.
Remember Homer, where Odysseus is saved from the wrath of Poseidon by a dolphin.
If dolphins did manage to get a message to us humans it might include things like, “Could please stop what you are doing to the oceans,” and “Please release me from this prison (the holding pens we keep them in) and let me swim free.”
Cetaceans have a large consciousness sphere, to use a term. We might think of consciousness as a large domain of possibilities and different forms of intelligent life in the universe probably have different “projections” into this domain. We happen to mentally project into some subset of this. We have hands and the ability to manipulate the world, language and the ability to accumulate a knowledge base. This means our intelligence has this ability to acquire “compound interest.” We can learn the thoughts of Newton and the music of Beethoven. This means recording thoughts in some form outside of the brain. The ability to manipulate fire helps a lot as well, something cetaceans will never do.
LC
I wouldn’t be too cocky aboUt dolphin potential. Sure, in their current form they ewon’t be too good at toolmaking. But when they evolve opposable thumbs, we’re screwed.
I wouldn’t be too cocky aboUt dolphin potential. Sure, in their current form they ewon’t be too good at toolmaking. But when they evolve opposable thumbs, we’re screwed.
If you go by “the sexual theory of intelligence”, dolphins outdo humans.
Bonobos use sex including homosexuality for social reasons, dolphins are even more displaying flexibility such as voluntarily (it seems) homosexuality and ability to use much everything for sexual purpose (corals, other species, toys, …).
It is a bad theory of course, because we would be dumber than any dog humping our legs…
I don’t think there’s any question that dolphins are capable of metacognition, as well as the demonstration of problem solving ability. The question is, are insects considered sentient beings because they can perceive movement of a predator? I would think not.
They did cover the issue of anthropic bias angle in their article – though I think the whole idea of life beginning “early”, is also an anthropic (or Earth-centric) judgement.
I suspect temperature is not just about keeping water existing as a fluid, but is key to the rate at which chemical reactions take place. Thus, a non-water-solvent chemistry will be less likely to support life (or to support rapid evolution of that life) if it functions at a low temperature.
The rate of most chemical reactions is temperature dependent, running faster at higher temperatures. Biology as we know it does probably requires water in a form where it is liquid or if in a solid form it is such that ice crystal structure at least intermittently slips or shifts so there is liquid behavior. Some Martian features display liquid-like flow from crater rims. Maybe the weight of rock layers provides pressure required for a liquid state. On the other scale it is possible that life in superheated water could exist, where pressure keeps water from vaporizing. However, chemical reaction rates are affected. Water molecules jostle bio-molecules, and at higher temperatures they do so with more energy. Higher temperature is associated with higher entropy, which erases information.
The bias for abiogenesis at an early Earth might have some basis if the physical condition of a new terrestrial planet is more favorable for pre-biotic chemistry. Without some sort of data like that, where we are not sure how to obtain it, the early Earth hypothesis is a sort of anthropic or Gaia-centric bias.
LC
This is a good basic scenario. However, there are new results that implies abiogenesis happens in the process of cooling from high to low temperature, thus avoiding both the rate and the genetic erasure problem.
[FWIW I added some commentary on that above. I dunno if it adds more meat as such, but there are references.]
Yo Steve, at the fourth paragraph, it should be: There are three doors, not “There’s three doors”.
There are three lights! Thanks.
Don’t give into torture Steve!
Another great article Steve; any article that can bring in ETIs and baked beans in one place is onto something 😉
Bring the beer!
I’m a skeptical of the author’s conclusions too. We don’t have enough data to draw any reasonable conclusions. We can extrapolate from Keplar data that habitable zone terrestrial worlds are likely common, and that life arose on Earth quickly. These are both encouraging starting points in the search for life.
What’s needed now is more gear in the sky that can reliably detect terrestrial worlds around main sequence G type stars.
If you were to stick two statisticians and two Australian Aborigines in the Australian Outback and told them to do whatever it takes to survive, you would probably find that, several hour later, the two statisticians have produced six bloody pages of analysis on the (im)probability of surviving in the Outback, whereas the two Australian Aborigines are already sitting down around a camp fire and eating some bush tucker!
Spot On. This made me laugh!
As Mark Twain said in his “Chapters From My Autobiography” : “Figures often beguile me, particularly when I have the arranging of them myself; in which case the remark attributed to Disraeli would often apply with justice and force: ‘There are three kinds of lies: lies, damned lies, and statistics.”’
Research tells us that 1 out of 20 examples of statistics are dead wrong.
[It is true! At least with 95 % certainty.]
This is ridiculous!
I mean, did you know that 98% of statistics are made up on the spot?!
LOL. A random sample tells me you are the better statistician here!
Somebody also told me once that the main cause of statistics is smoking! 😀
Unless of course that is two Australian statisticians, in which case you will find them at the nearest pub.
Indeed, and they will probably bore the hell out of everybody in the pub by lecturing on the risks of Alcohol Consumption in Australia!
That is one way to solve the lectured problem.
But would they do that, it would lower the likelihood of pubs for their next round of “Australia Survivor”?
Maybe after too many beers they would…
Indeed, and they will probably bore the hell out of everybody in the pub by lecturing on the risks of Alcohol Consumption in Australia!
If you were to stick two statisticians and two Australian Aborigines in the Australian Outback and told them to do whatever it takes to survive, you would probably find that, several hour later, the two statisticians have produced six bloody pages of analysis on the (im)probability of surviving in the Outback, whereas the two Australian Aborigines are already sitting down around a camp fire and eating some bush tucker!
The paper will take a bit of study to read in greater detail. The Monte Hall argument can be seen easily if one were given 10 curtains, or 100 of them. You choose one of the curtains, and Monte Hall then opens all of the remaining ones except yours and some other one. So if there were 100 curtains you have 98 opened with nothing, there is the one you chose and another one. It is pretty clear you had better switch.
The argument of this paper appears to be that what ever process there is for abiogenesis, it has some probability for occurring in a time interval under the right conditions. The argument is then that this probability is
P(?t) = 1 – exp(-??t),
where this might be taken to be compared to getting a royal flush in a poker hand. Now every combination of cards in a poker hand, say 5 card stud game, has an equal probability. This includes a combination of cards with no matching numbers, suits and so forth. We categorize valuable hands according to the restricted number of ways we can define them, and the value of the cards. There is only one way to get 4 jacks, 4 different ways to get 3 jacks, and so forth. Every specific combination of cards has the same probability. The above probability is for small time interval P(?t) ~= ??t, and if this is very small we might compare this to getting combinations of cards in a poker hand. The probability of getting a royal flush is the same as getting 4?, 3?, 6?, J?, 6?, which is a lowly pair of sixes. What makes this hand unspectacular is there are many ways one can get a pair of sixes. However, if you get the royal flush on the first hand or maybe early in the game, that is equiprobable with getting it next year after playing over 100 games.
So the posterior probability is then ultimately heavily dependent on the Bayesian prior you use, which the authors say is “Life is highly probable because we know it started earlier in the history of Earth.” This is not too far off from the knucklehead playing slot machines with the idea that after a stream of bad luck that luck has to be on their side with this next throw. This is a sort of gambler’s fallacy — one casino houses “bet on.”
What might make this adjusted with whether the chemical and physical conditions for the formation of life are most optimal at the early formation of a planet. It might be that the more intense volcanism, outgassing, thermal vents, and so forth give more favorable conditions for abiogenesis. A planet later on settles into a more staid situation with a reduced probability for the chemical-physics conditions required.
I don’t think life on Earth is a complete fluke. There is something to the Copernican principle, which says that conditions in one region of the universe have some probability of occurring in other regions, and that the physical principle here and the same as over there. It just might be that life is not an abundant thing in the universe, and it is likely that complex life even more so. A biologically exuberant planet such as Earth might be a pretty rare thing in the universe. Analyses I did back in the 1990s indicates there might only be around 10^2 to 10^3 Earth-like planets in this galaxy. There might be far more Mars-like planets which could have basic life forms on a prokaryotic-like level.
LC
I think their argument had some built-in anthropic (or at least Earth-centric) assumptions about timeframes. A slightly different base chemistry could significantly alter the timeframe and propensity of abiogenesis on a different planet. Maybe life emerged late here – maybe intelligence doesn’t take nearly as long to evolve elsewhere?
I actually think intelligent life is pretty rare, in fact exceedingly so. How ETI is defined is a bit arbitrary, but any life form which can fabricate advanced technology (say making steel, or a radio system etc) might be a start. SETI is useful in putting a lower bound on ETI existing in the universe, or #ETI per galaxy. As for biology in general, that is a bit of an unknown. I actually think it is somewhat prevalent. However, I suspect it is what I would call “Mars-life,” or what biology on Mars might look like if it is there. This is minimal life in cellular complexity and adapted for conditions extreme compared to Earth.
LC
Whatever opinions may account for, I think the fifty plus years of eerie silence raises some doubts of star trek/ star wars universes where we rub shoulders with technologically advanced aliens.
However, finding micro-life (or at least fossils) on Mars remains quite plausible and just one SETI find would be astounding. Definitely worth continuing the search.
i also believe that inteligent life is rare. But what is rare. If there are 1 billion inteligent life spread out in 125 billion galaxies than it is stil rare. Than every 125 galaxies has 1 inteligent creature. We will probably never find 1 of them. I do not think we will find any in our galaxie.
b
It is impossible to say.
The problem with intelligent life (lets assume HEI for the moment) is that it likely develops in a competitive environment. Our own planet is a prime example. Thus, any such civilization will likely have created various means in which to compete with other lifeforms, tame it’s environment or compete against other members of its own species.
There is a risk that these tools and or weapons could lead to a civilization terminating event(s). The longer any civilization exists, the longer these risks persist, giving rise to a greater likelihood of a catastrophe.
Certainly, the more optimistic could argue that this risk metric isn’t universal. Perhaps a civilization could have a collective intellectual epiphany; act to mitigate such risks. This seems unlikely, at least when I look into the mirror and ponder such ideas.
Civilizations may be rare. The silence from SETI is a prime example. We may indeed be the only civilization presently active in our galaxy. Biospheres may be more common and simple organisms living in harsh environments even more so.
The Milky Way galaxy has +- 200.000.000.000 star systems
Please be a bit more optimistic.
The Coperican Prinsiple is very reasonable.
Looking for absolutes is very frustrating when everything is a probability
Most likely that is the case. The extrasolar systems we have identified so far are largely very different than ours, and it poses a question of whether or not Earth-like planets are that common. I worked out the chaos theory of solar systems and found that extrasolar systems that are G-class identified up to about 9 years ago would perturb a putative terrestrial planet at 1AU far more than Earth is perturbed. My conjecture is that highly complex life requires a fair degree of orbital stability, for otherwise a planet might over the course of a few million years or tens of millions of years experience huge swings in temperatures and physical conditions as its orbit is shifted around by other gravitating bodies or jovian planets. This might permit a Mars analogue, or some planet with life on the complexity level of prokaryotes, but a bio-planet with the abundant exuberant complexity of life we have on Earth is probably very exceptional.
The Kepler type observations may give further clues to this. We might find Mars-like planets, where data on the photo-chemistry of atmospheres could reveal signature of biology. Maybe Mars actually has an ecological system of prokaryotic-like life forms as well in the regolith or subsoil of the planet. If we are lucky we might find in some extra-solar system a “super-Mars,” or a planet with about the mass of Earth and thicker atmosphere, where it could have a prokaryotic ecosystem that is much more extensive than what Mars might harbor, and which leaves more of a chemical fingerprint in the atmosphere.
As Gekkehenkie indicates it is likely that ETI is extremely rare, occurring on average maybe once for every 1000 galaxies or so. I doubt there will be Star Trek or Star Wars scenarios of interstellar “communities” that interact with each other. I am not terribly optimistic about our species heading out into interstellar space and the like. It is extremely unlikely that the converse happens so that a flying saucer lands on the Whitehouse lawn.
LC
Agree. I think the most likely scenario is a long distance conversation with very long light speed limited pauses between each side of the conversation.
Hopefully. This might be a best case scenario. The distances to the next HEI may be so great as to make contact nearly impossible.
I do hope to see the day when we detect other biospheres. This at least I am optimistic is achievable in a time-frame of years. e should still be kicking around when this type of discovery is confirmed.
You may believe this or not, but I have a model for that too…
But I will spare this thread. Short and long: here you can put up many and conflicting models. Which means testability isn’t really enough, even if you would be lucky and find it.
Biologists feel that intelligence in the ETI sense is a rare function akin to the development of the Elephantidae trunk; it may happen once on a blue planet. It may be rare seen over many planets, and is sufficient to answer “where are they”.
I’m sorry! They must have passed you by.
Maybe the next time they visit.
I’d hate for you to feel left out
If you are implying you are seeing UFO ETIs, “you are not alone”. I think they have clubs for that now, “how I met an alien and lost my virginity” or something such.
An update: FWIW, further comments made me put the toy model up in this thread. It shows how you may have widespread intelligence (after a migration wave), but no way of detecting it.
[So it’s not a new idea, but the toy model may be.]
Does this mean that we won’t be accepted into the Galactic Federation of Planets ?
Does this mean that we won’t be accepted into the Galactic Federation of Planets ?
The most boring conversation ever
I think the SETI sets the bar here by defining a “useful” ETI.
Sort of the same as how language is seen as the basic human trait. (For Homo it may well be the relative smallness of incisors instead.)
If we ask the SETI Project, which should be experts, that the seeming silence is a problem is not what they think. Apparently the attenuation of broadcast signals gets the SNR down so that we have currently covered ~ 0.1 % of the sky and radio spectra combined. (Whether we look at broadcast or narrowcast.)
IIRC they want to ramp up, in which case we can arrive at a rough but sensible answer within a couple of decades. It is in their white papers on that site.
Fifty + years is not even a blink of the cosmic eye lid
“The Monte Hall argument can be seen easily if one were given 10 curtains, or 100 of them. You choose one of the curtains, and Monte Hall then opens all of the remaining ones except yours and some other one. So if there were 100 curtains you have 98 opened with nothing, there is the one you chose and another one. It is pretty clear you had better switch.”
Never saw this as a good explanation really, why would he not just open one of the other doors?
A clearer explanation of why you should swap is to remember that to win with a strategy of not changing you have to pick the right door straight off at a probability of ?, while by always changing you can (and must) pick either of the wrong doors initially at ?. Since Monty Hall always shows you a wrong door after you made your initial selection, the other one must be the winning one.
This is pretty close. You know before Monty opens the wrong curtain you did not choose that the two you did not choose has a probability of 2/3. Once the curtain is opened the probability for the two is 2/3, but you now have additional information, you prior estimate is better. However, the probability for the two is still 2/3, but you just now have the additional piece of information that the probability for one of them is 0, so the other must have P = 2/3.
LC
This was a very inspiring comment in the context. (Which a similarly inspiring article set up!)
FWIW I added some commentary on different chemistries and abiogenesis rates above. If you can plough through it, you may find it interesting.
If you look arrond you will see that nature works the numbers game with infinite quantities & an infinite variety of those quantities in self similar cycles.
Regarding Monty Hall… once he opens the door and reveals the goat, the probability of your first choice goes up from 1/3 to 1/2. It is a conditional probability now – the odds of you picking the right door, *while knowing that one of the other doors has a goat behind it*.
The opening of the door revealing the goat thus increased the odds of the car being behind one of the two other doors to 50%, and so it makes no sense to switch doors.
In other words, if you look at 10,000 games in which the player chose a door, and then Monty opened another door revealing a goat, and the player did not switch, then in approximately 5000 of them the car is behind the door the player chose. Those 10,000 games, however, represent a biased sample, since there are another set of games in which the door was behind Monty’s door, but we’re not counting them.
k? just in case you’re ever in that situation.
However, if you’re playing wait-wait-don’t-tell-me, that a different matter of course 🙂
I think you’ll find there are years of furious debate underlying this one. The outcome is skewed by the fact that Monty knows where the car is and will aim to keep it hidden.
If you pick the car first – then it doesn’t matter which door he opens, but there is only a 1/3 probability of this outcome.
If you don’t pick the car first – the door he then opens becomes very significant – since he will always open a goat door, meaning the car must be behind the remaining door. There is a 2/3 probability of this outcome – since there is a 2/3 probability that you won’t pick the car first.
You can see the math and diagrams etc if you go to the link in the article.
Steve – let the Player decision be called Px (P1,P2,P3) and the car will be behind Door Dx (D1,D2,D3). Thus PnDn is a winning game, and PnDm where n!=m is a losing game.
The original list of options is P1D1,P1D2,P1D3,P2D1,P2D2,P2D3,P3D1,P3D2,P3D3
Since P and D are independent, these are 9 equally-likely choices.
Suppose I chose D1.
So the new possible list is P1D1,P1D2,P1D3 and only the first one is a winner – thus my odds are 1:3.
Now Monty opens door 2 and shows it is a goat.
The new full list, after the new information is factored in is:
P1D1,P1D3,P2D1,P2D3,P3D1,P3D3 (since we know D is not 2)
I can now either stick with D1, and the options are:
P1D1 and P1D3 (50% winner)
or I can switch to D3, and the options are
P3D1 and P3D3 (50% winner)
Clearly, I won’t choose P2 since that list is:
P2D1 and P2D3 (0% winner)
—-
Here’s a simpler take on it:
Imagine you’re one of three finalists in the Mr. Universe pageant, and so your odds of winning are 1:3. Once one of the OTHER guys is pronounced Mr. congeniality, your odds become 1:2, as do the odds for the other guy.
—
Actually, we can argue this by symmetry. Suppose there were three players, and each chose one of the doors. When Monty opened door #2, player #2 realized he lost. Now you’re saying that player #1 should switch to door #3… but then player #3 should switch to door #1… and both will have better odds ?!
No. Some great minds have been over this. It is not my idea. Check the link to the Wikipedia article. Unless you picked the car first (1/3 chance) – Monty will ensure the car is behind the remaining door (2/3 chance).
Monty acts differently in response to whatever your first choice is – neither of your ‘simpler take’ analogies fit this context.
I’m well familiar with the material in the wiki article. They are mis-applying the conditional probability formula, getting confused because of the “Monty Free Will” issue. P(A|B) is not 1/3, and this can even (as a last resort) be verified empirically.
However, for a gut fell, consider the 100-door example given by lcrowell… After 98 doors have been opened and revealed as goats, do you really think my odds are still 1:100? or have they improved to 1:2 (the two remaining doors)
Are you a statistician? Do you have an advanced degree in statistics? Stop arguing, you are wrong. Simulations done using playing cards prove you are wrong. Go read the wikipedia article and you will see.
To take an extreme case let’s say there’s 1,000,000 doors. The probability that you picked the door with the car is 0.0001%. Monty, who knows what door the car is behind, opens 999,998 of the remaining doors and leaves 1 closed. The probability that the car is behind your door is still 0.0001%. It hasn’t changed just because Monty opened the other doors. That means that the probability that the car is behind the remaining unopened door is 99.9999%. You would be an utter fool not to switch doors.
If the idea is to get you to switch then yes, I’d call it a bluff, call him and stick with my door.
The overarching rule is that unless you pick the car first, Monty will act to ensure the car is behind the last remaining door.
If there are 100 doors, there is a 99/100 probability that you won’t pick the car first. That will be the probability that the car is behind the remaining door.
I see the light after a nights sleep. Probability is dependent on prior knowledge. I was considering probability w/o human intervention. duh!
Read my argument above with 100 doors. You chose one, Monty opens 98 doors to reveal no prize and there is your chosen door and another one still closed. Do you switch? Think about it, you better. This is taking a “large limit” on the problem. Even with 3 doors, yours has 1/3 chance of winning and the other two have 2/3. With the one door opened the only thing which changes is the Bayesian prior estimate pertaining to the other unopened door, but not the joint probability. The 2/3 chance for the previously two unopened doors has now shifted to the single unopened door you did not choose. Your odds of winning increase by two if you switch.
LC
98 is the same as three…. if Monty opened 98 doors, then my odds of having won the car just improved from 1:100 to 1:2, since there are two remaining doors.
At this point, switching doors won’t matter.
Are you seriously saying that AFTER 98 doors have been opened, if I stick with my original choice, I still have only 1:100 chance to win?
—-
Try the symmetry argument again:
Suppose there were three players, and each chose one of the doors. When Monty opened door #2, player #2 realized he lost. Now you’re saying that player #1 should switch to door #3… but then player #3 should switch to door #1… and both will have better odds ?!
I suppose this is why probability can be confusing. With the 100 doors any door you choose has a 1/100 chance of winning. If Monty open 98 of then except yours and another door, the probabilities for your door remains at 1/100 and for the other 99 as 99/100. However, you just now just know that 98 of those 99 doors do not have the prize, so the other door is P = 99/100. Change 100 to 10,000, would you seriously stay with the door you initially chose? I don’t think so.
LC
But, it’s a new ballgame if you decide to change your choice of the remaining 2 doors (which I believe Monte would not allow). Now, instead of 1/100, it’s 1/2 regardless of the one you choose.
How does knowing that all of the other doors are empty except yours and some other change the probability that your choice is p = 1/n of being correct? Suppose there are a million doors, and yours and some other remains closed.
LC
I apologize up front LC. My shallow thinking tells me that no matter how many doors we start with, if after Monte opens all the doors except the one I chose and 1 other and no new car appears and then offers me the chance to change my choice of doors and start the contest over, the odds/chance/([probability?) now are at 1/2 right?
Imagine the game was repeated 100 times. If you truly had a 1/2 chance of winning each time you played the game, you would win about 50 times.
Despite having a billion, trillion doors to choose from, you somehow managed to pick the right door 50 out of 100 times.
It’s just not plausible, and a careful analysis of the statistics explains why.
I don’t know how else to argue, but you are simply wrong. With 100 doors the probability of being correct is p = 1/100. The subsequent opening of the other doors does not change that probability. What is changed is a Bayes prior estimate, which tells you that of the 99/100 percent probability of the prize being in the other 99 curtains, is now restricted to one particular curtain in that set.
http://en.wikipedia.org/wiki/Monty_hall_problem
LC
I think you do it right, because I had an easier time to follow your argument than previous attempts elsewhere.
The problem seems to be bayesian priors; a good example how iffy they are to use in daily life.
I understand what LC is describing as well as others, and I think you’ve all done a pretty good job at trying to help those still arguing understand.
We’ll try it using percentages instead of fractions to see if that helps.
Essentially, you start with 100 doors. That means each door has 1% chance of being correct and a 99% chance of being wrong. So you choose 1 door and there’s the 99 others remaining. Altogether, there’s a 100% chance that the car is behind one of the 100 doors, but if you’ve taken 1% away by picking a door, that leaves 99% for the other 99 doors. This means that you have a 1% chance of choosing the right door, and there’s a 99% chance of it being behind one of the other 99 doors…this is simply added together.
Now you know for a fact that Monty is going to pick only the wrong doors. This doesn’t remove their combined percentage of being correct from the total equation. You made your choice based off a 1% chance and it will always be 1% because it was chosen from a possibility of 1 out of 100. If he opens 98 doors, that leaves just 2…which if you were to make your choice THEN and not before, you would have a 50% chance. If Monty gave you 100 doors, and then took 98 away without having you pick beforehand, you could pick with a 50% chance because you know the car is in one or the other. You made no choice prior and therefore it isn’t a factor in your chance of picking the right one out of 2.
However, you made your choice at the start with 100 possibilities, not with the 2 options you have now…that means that there’s still a 99% chance that you chose the wrong door and therefore a 99% chance that the car is behind the other door since the other 98 were eliminated.
The same is true with the 3 doors. You have a 33% chance of having picked the right door, and a 66% chance that you didn’t. For me, those numbers are close enough that I would base my decision on whether to switch based on how I perceive the situation at the time. You’re not a fool if you switch because the percentages are with you, but 33% is not really a bad enough possibility for me to say that you’re a fool if you don’t.
I remember Carl Sagan once said that either the universe is teaming with life, or that we may be pretty much it (at least for intelligent life). My intuition has always led me the latter conclusion. Not very scientific, but still in the ballpark as evidenced by this article. But..we have not yet reached the Model T stage of space exploration,etc. Many exciting discoveries await, alien intelligent life or no….
Carl Sagan was a visionary. Nevertheless, he made those statements before we started finding all those rocky worlds around dwarf stars. I’m optimistic life exists, the statistics game is pretty good from the look of it. There may be a lot of inhospitable worlds with simple extremeophiles and various slimes. Rich biospheres may be less common and ETI may be rare indeed.
This model starts out from a Poisson model of abiogenesis attempts. Remember folks, you heard it here first: “I will be using a first order testable Poisson model for abiogenetic attempts.”
Seriously, I don’t know whether to be gratified because professional astrobiologists shore up my understanding of the subject, or be aggrieved because they take the idea to the opposite conclusion from mine.
That conclusion is that the timeline of life may get us information.
We observe that life on Earth didn’t occur halfway in on the biosphere lifetime, which is estimated to be ~ 5 – 7 Gy. Let us try a stochastic model to see what we can get out of that.
Abiogenesis, having probiotic chemistry evolve into protobiotic cellular life, could be a repeated process of attempts over time and locales. In the simplest stochastic model this belongs to the family of Poisson processes.
Such processes stacks their probability mass early, due to their exponential distribution. A homogenous Poisson process has P(T > t) = e- λt.
This is a testable model.
To simplify we use a normed distribution where observation time t = 1. Since this is a one-sided interval from t = 0, we want to have a set of distributions with at least 0.99 of the probability mass within the interval.
The probability mass is expressed by the cdf (cumulative distribution function). Inserting into the Poisson cdf, we get F(t,λ) = 1 – exp(-t*λ) >e; 0.99 → t*λ > 4.6.
Now t = 1 corresponds to &lambda ~ 5. That means the normed waiting time T ~ 0.2. With actual time t* ~ 5 Gy we get actual waiting time T* ~ 1 Gy.
With current understanding we have putative observations of life from ~ 3.8 – 3.5 Gy ago. Earth aggregated ~ 4.5 Gy ago, which means the interval gets close to the required <e; 1 Gy.
Before I get to the caveats raised by the paper, let us look at if such a model achieves what it set out to do.
In principle a stationary process means a stationary mechanism in a stationary environment.
This isn’t what happened at the start, since volatiles were collected, temperatures and pressures going down and tectonics started. But since it *looks* stationary it means it was close to stationary in some stochastic sense, even if it was frustrated in actuality. In this sense the process was robust and the environment stable enough.
Further smaller wait time, which could be even smaller if tectonics had allowed observation, means that there were many parallel attempts. Larger wait time considered above means deterministically either fewer attempts over long time for some reason or fewer successful for some other. Both is indicative of deterministic difficulty.
Further as opposed to other situations in statistics there is no inherent problem with having just one data point, though it is a lousy statistic. So this is indeed informative.
Now for possible caveats:
This can fail internally or by putting a more predictive hypothesis (since this is the simplest in its class).
Internally:
1) The process isn’t stationary after success (since existing life interrupts it). As argued above, this is not a fail.
2) The process can succeed numerous times, in which case it is a Lévy process. This is a complicated process to understand. However:
– If it looks like a compound Poisson process, a generic class of simplest Lévy processes, the model still applies.
– Post-event the phylogenetics looks like 1 success (a universal tree).
Externally:
– “What if” the observation had been closer to observation time t?
Such test wouldn’t have been possible to do with such confidence. That doesn’t affect this test that is to be scrutinized for its failure, not its success.
This is the Poisson argument used. The paper has various sigmoid graphs of life approaching unit probability as time advances. The thing we do not know is the value of ?, which is probably not constant. The model assumes a constant ? in time and makes assumptions about it from planet to planet. Is suspect it declines as the planet matures, for the planet is less geologically active. I conjecture that pre-biotic chemistry emerged in hot pools, vents, and maybe in such an environment where these was some sort of proton pump chemistry which energetically drove the process. These conditions are less abundant today, where during the first billion years the Earth may have been seething with the chemical caudrons.
This probably does answer the question of “where are they?” We may never know. We may say that they are too far away to communicate with, or that they do not exist. If we do find other bio-planets the hypothesis for ETI remains open, but it may never be answered.
Interestingly this thinking can be applied to multiverse ideas as well.
LC
Thanks for the response!
As I discussed in the other comment, taking attempt rate λ as stationary is not a bad model.
One can further suspect that it settles into a quasistationary state, as long as plate tectonics maintain the release process of heat flow through the crust at the everlasting plate boundaries.
But even if it wasn’t so, the one example of Earth may suffice to inform us on the general easiness of abiogenesis, as I described above. Whether rates elsewhere varies becomes secondary to that, then we need to understand what if anything would lower the rate.
I suspect that the chemistry would make a difference. However, water-CHNOPS should be the likeliest outcome.
I agree that another result would bear on the Fermi question. However, the question is insufficiently constrained to invalidate a result that implies easy abiogenesis.
[In fact, the more likely hypothesis that accords with biologist thinking here is that technological intelligence is a rare trait.]
This I don’t agree with, at least for the moment. I think Bousso’s suggestion, to use the proxy of dust formation, is an excellent suggestion.
That takes the anthropic principle to an observer independent, chemistry independent, easy to apply environmental principle. The ease comes from that the dust proxy can be further replaced by entropy formation.
What could be wrong with that? Maybe the largest problem is to drop the new place at the center stage that the anthropic principle gave us, after the copernican principle pulled us off the first time.
Now we have a conundrum. Testability argues for one model that predicts that life is not rare based on data (see my previous comment). A bayesian analysis claims that it is not.
– Let us take the comparison first.
In my comment I treat much of what they argue is a problem for a simpler model, such as occurrence of several rooted trees of life. And as I noted there, a testable model can’t be falsified by another model, it must be out-competed.
Further, a ~ 36 % probability of life @ 5 Gy is comparable with earlier results. IIRC Lineweaver et al gets ~ 18 % with their Las Vegas approach. (Not to be confused with the Monty Hall problem … I think.)
Naively the bayesian approach suggested here fails in a comparison. It would be a more complex model by way of introducing parameters describing different priors.
– Let us look at the bayesian model as such.
AFAIU the model isn’t testable.
Further, while I don’t know about bayesian models and how they are used in statistics, the usual bayesian approach one can see is choosing the best parameter set within a specific model. This is what the WMAP team did to choose the parameters of the standard cosmology. And this is how biologists works bayesian methods in phylogenetic trees.
To use it to choose over distributions, or equivalently different stochastic processes as I understand it, seems fraught with problems. You add degrees of freedom, which in frequentist statistics means you allow yourself the luxury to fit anything. But a method that predicts everything doesn’t predict anything, again it isn’t testable.
[Just for kicks I may insert a model that informs on and answers the paper’s concerns about variation over time in an abiogenetic process. But now I need to get to a coffee shop!]
Some arguable points in the article:
That is a philosophical point. Especially here, it turns out.
If you are a frequentist statistician, it is correct that you should demand that several events could happen to have a cumulative distribution function on what is called a measurable distribution.
Here it doesn’t really matter if you take a sample or make another estimate. (Say, using the data point available.)
Then in the naive picture of only looking at data you have a problem. You can’t use one data point from one event to ascertain that you have a distribution with several events in the first place!
However, that is a philosophical approach. As always actual models* is a way out of such problems. Here you can assume that you have a stochastic process (say), and self-consistently use a poor estimate.
Actually they don’t. The stationary process they use say that all these people eat baked beans similarly (same appetite).
What the process tells us is that the appetite doesn’t change because dinner is interrupted by a phone call.
[Well, a longish call might. But please stay with the analogy! :-P]
And the problem is to be sure that is valid. If the dinner was quick, the chance that there was a phone call interruption (or change of appetite) becomes minute.
——————–
* And testability, for that matter.
My dinner is never interrupted by a phone call – I ignore the damn thing!
See? No change of appetite!
If it takes a loaf of bread 2 days to go all green sitting out in my dank, filthy kitchen… How much does that contribute to our knowledge of the likelihood of mold growing AT ALL on a loaf in your dry, tidy one…?
http://i.imm.io/7vqY.jpeg
alslam
I was educated and trained a scientist and engineer and have huge respect for the achievement of innovative and inventive scientists and engineers the world over, whose endeavours have lead to vast improvements in both our physical and material wellbeing. As a result of that training, in solving a problem I will always try to take a logical, scientific approach to it. However, in regard to the universe and the prospect of finding any form of life in another part of it, I firmly believe that, however long we humans exist on this planet, we will never find it, nor will we ever fully understand the universe itself; the laws of probability dictate that there is always an element of doubt about the results of any test of scientific thesis; nothing is one hundred percent certain. Our continuing quest to solve this riddle of the universe is admirable, but in the final analysis, it is nothing if not escapism… we are running away from the deeply serious challenges that we face on this planet!
I therefore believe that, instead of wasting so much of our time and resource chasing dreams in outer space, we should apply all our resourcefulness, brilliance, invention and innovative ability to solving the problems we have here on earth: and these problems, it strikes me, are primarily concerned with the distribution of its raw materials in relation to its populations; in other words, feeding ourselves effectively and keeping ourselves warm (or cool), as well as settling on some way of resolving the paradox, rooted in the enduring ability humans have had throughout our history, for the inequitable distribution of its assets, particularly those that are unearned.
I know my comment may seem to be unhelpful, considering the honest, scientific nature of this article, but I’m afraid that we are losing site of the endeavour in which the human race really needs to indulge itself, with unfettered enthusiasm, courage and great, great urgency, before it becomes too late for us to tackle. The big question remains: who has the courage to start this debate and who will initiate it.? Someone with influence and the power to do so… a paradox indeed.
Governments already put a critically low emphasis on space science. Your argument is already won.
I am not sure what your reasoning behind this statement is. There are many valid reasons to suppose otherwise. Keplar data, statistical projections, the diversity of environments for life here on Earth, the possibilities for unusual life with different chemical makeups, the abilities of microbes to withstand vacuum-irradiated conditions and the sheer size of the universe all point to the likelihood of life elsewhere. Observations show that the same physics at apply here as in the furthest reaches of the cosmos, indicating that similar processes which spawned life here may be at work elsewhere.
It’s just a matter of patience. I for one, would like to keep opening doors – even if we keep finding goats. Some doors are going to require a better lockpick, creative ways to open, or just more telescopic muscle.
One day will will get a car, even if it means stashing a heck of a lot hay in the interim.
Uncle Fred, with respect, I don’t question any of what you say above, but I do question its validity for the finite future of life on earth. I never said that there is no ET life out there; what happened here on earth 3Bn or so years ago could well happen somewhere else in the universe. What I did say is “we will never find it”. Statistical projections, particle and quantum physics models and hypotheses may abound until the cows come home, but, unless we can genuinely observe the thing we are searching for, we will never be certain it exists. You can be as patient as you like, and stand by as many doors as you will, but we are chasing dreams – and the mountain of hay will cost us all :-).
There are ways to observe life from Earth. Atmospheric chemical signatures are the first port of call. Even with today’s telescopes, we can distinguish the different elements in gaseous extra-solar planets. Life on Earth keeps our atmosphere unstable. It is an artificial mixture of oxygen/nitrogen. Without life, this mixture wouldn’t likely exist. Though such a mixture detected in another terrestrial planet would not be definitive proof of life, it would be highly suspect.
It is also possible to measure the reflectivity of a nearby planet. This observational technique will be more prominent in the next generation of telescopes. By measuring the volumetric qualities of reflections, we may be able to detect if the planet is home to extensive foliage.
Many other factors could be indicative of life, or at least indicate conditions on a planet are favorable to its formation. Oceans of liquid water, the arrangement of Jovian giants within a system, and other conditions.
Obviously, the only way to be 100% certain is to send a probe, or hit the jackpot and discover some recognizably artificial signal. Neither of which are likely going to happen in the short term (I’m not convinced the latter may happen at all). Even if we did send a probe, the cost (though high) would still be well within our ability to absorb.
Where I draw the line on costs is in the realm of manned space exploration. Space colonies, Martian trips, and Lunar bases do not make sense from a cost-return perspective. These nationalistic ventures were never really about science. They largely belong to another era where cold-war politics was king, and robots couldn’t do the exploration for us.
LC pointed out earlier that our Earth is our spaceship. Not to over-inflate his ego, but this is a genius comment – we should start seeing the it as such. Space science by robots is cheap, sending man to far off celestial destinations is not.
As for taking care of our own problems, I agree wholeheartedly. However, NASA’s budget is small. To put it in perspective, the US military spends over 20 Billion to provide air conditioning to the troops. That’s more than NASA’s entire budget, manned space exploration and all!
http://www.huffingtonpost.com/2011/06/21/air-conditioning-military-cost-nasa_n_881828.html
Uncle_Fred, thanks for your response. I’ve put in another long comment above in answer to a number of other responses to my original comment including some of your points; had no idea it would generate this much interest, but there you go! Only thing I’d add to yours is I agree NASA’s budget is smaller than the money we UK taxpayers leant to our banks! And budgets are additive; even the military costs could well reduce if we get our act together, politically and socially speaking.
Yes I agree, brilliant notion of earth as the spaceship, our survival pod, if you like. We have to respect it.
I have to disagree about abandoning the quest to understand the universe. I would like to think we can come to understand the universe as at least an effective theory that unifies gravitation and quantum mechanics. I do not know to what extent this can ever be a final theory or a theory of “everything.” It would be of interests if we humans can observe the universe at least up to the limits of what is observable and to codify this within some math-physical language that is within our mental abilities to understand.
I do agree that we need to readjust our energy-entropy balance on Earth. I would also say that I have written here on numerous occasions here on UT that ideas of moving off to other planets in colonies and the rest in order to save ourselves is ridiculous. In some sense this planet is our “spaceship,” as it orbits a star, a star that orbits a galaxy, and a galaxy which is on an accelerated co-moving frame in a de Sitter vacuum cosmology. It makes little sense to tear up our spaceship in order to make trifles and trinkets.
The one thing which has to be taken into account, and this is the most difficult part, is that in order to readjust our situation on this planet in some sustainable form, even if quasi-sustainable on just a longer term, it requires a different sort of economy. This is why there is such political resistance to issues of the environment and now global warming. If we were to really get serious about working on these problems it means restructuring the entire national and global economic system. Since the guys who really run our world are those who own it, which are the mega-financial and corporate sectors, they are not very forgiving on this front. This is the major problem we face, where those who own most of everything care only for quick profits now at the expense of our longer term prospects.
LC
I have to disagree about abandoning the quest to understand the universe. I would like to think we can come to understand the universe as at least an effective theory that unifies gravitation and quantum mechanics. I do not know to what extent this can ever be a final theory or a theory of “everything.” It would be of interests if we humans can observe the universe at least up to the limits of what is observable and to codify this within some math-physical language that is within our mental abilities to understand.
I do agree that we need to readjust our energy-entropy balance on Earth. I would also say that I have written here on numerous occasions here on UT that ideas of moving off to other planets in colonies and the rest in order to save ourselves is ridiculous. In some sense this planet is our “spaceship,” as it orbits a star, a star that orbits a galaxy, and a galaxy which is on an accelerated co-moving frame in a de Sitter vacuum cosmology. It makes little sense to tear up our spaceship in order to make trifles and trinkets.
The one thing which has to be taken into account, and this is the most difficult part, is that in order to readjust our situation on this planet in some sustainable form, even if quasi-sustainable on just a longer term, it requires a different sort of economy. This is why there is such political resistance to issues of the environment and now global warming. If we were to really get serious about working on these problems it means restructuring the entire national and global economic system. Since the guys who really run our world are those who own it, which are the mega-financial and corporate sectors, they are not very forgiving on this front. This is the major problem we face, where those who own most of everything care only for quick profits now at the expense of our longer term prospects.
LC
I have to disagree about abandoning the quest to understand the universe. I would like to think we can come to understand the universe as at least an effective theory that unifies gravitation and quantum mechanics. I do not know to what extent this can ever be a final theory or a theory of “everything.” It would be of interests if we humans can observe the universe at least up to the limits of what is observable and to codify this within some math-physical language that is within our mental abilities to understand.
I do agree that we need to readjust our energy-entropy balance on Earth. I would also say that I have written here on numerous occasions here on UT that ideas of moving off to other planets in colonies and the rest in order to save ourselves is ridiculous. In some sense this planet is our “spaceship,” as it orbits a star, a star that orbits a galaxy, and a galaxy which is on an accelerated co-moving frame in a de Sitter vacuum cosmology. It makes little sense to tear up our spaceship in order to make trifles and trinkets.
The one thing which has to be taken into account, and this is the most difficult part, is that in order to readjust our situation on this planet in some sustainable form, even if quasi-sustainable on just a longer term, it requires a different sort of economy. This is why there is such political resistance to issues of the environment and now global warming. If we were to really get serious about working on these problems it means restructuring the entire national and global economic system. Since the guys who really run our world are those who own it, which are the mega-financial and corporate sectors, they are not very forgiving on this front. This is the major problem we face, where those who own most of everything care only for quick profits now at the expense of our longer term prospects.
LC
I agree with the science side of this.
But when we come to the societal side, there is little here I can get a handle on. The space exploration/exploitation bit I answered above.
What does that even mean? We are situated in an extensive flow of energy and hence an immense production of entropy.
The problem seems to be the reverse, we are able to use very little of that. Foremost, it is efficiency that has taken us from earlier wasteful hunter-gatherers and early agrarians to the resource-rich society of today. To become more efficient we need to invest even more.
An equally valid analogue would be that it makes little sense to keep our spaceship boringly utilitarian. “Tear up that dilithium chamber and make me a bracelet; we have too many reactors and no recreation room!”
I seriously doubt any reputable economist think so. They seem to think market economy works well to regulate these things. An example I saw the other day was that deep sea oil is projected to cost twice as much to produce, which will nicely start to wean us from it.
And as they say on “other theories”: “show me the money”. Develop these “different sort” methods, then show us that these works at least as well as today’s methods.
I would think that if there were something in it, it would be fruitful. But so far they have been sorely lacking. (Communism and other dictatorial commando economies; are there more alternatives?)
I agree with the science side of this.
But when we come to the societal side, there is little here I can get a handle on. The space exploration/exploitation bit I answered above.
What does that even mean? We are situated in an extensive flow of energy and hence an immense production of entropy.
The problem seems to be the reverse, we are able to use very little of that. Foremost, it is efficiency that has taken us from earlier wasteful hunter-gatherers and early agrarians to the resource-rich society of today. To become more efficient we need to invest even more.
An equally valid analogue would be that it makes little sense to keep our spaceship boringly utilitarian. “Tear up that dilithium chamber and make me a bracelet; we have too many reactors and no recreation room!”
I seriously doubt any reputable economist think so. They seem to think market economy works well to regulate these things. An example I saw the other day was that deep sea oil is projected to cost twice as much to produce, which will nicely start to wean us from it.
And as they say on “other theories”: “show me the money”. Develop these “different sort” methods, then show us that these works at least as well as today’s methods.
I would think that if there were something in it, it would be fruitful. But so far they have been sorely lacking. (Communism and other dictatorial commando economies; are there more alternatives?)
The most important thing to realize about economics is that it is all artificial. There are no economic rules in nature. We might try to emulate ecological systems in an economy, which might have some merit to it, but it is still a created game. Economics is an artificial game even though economists try to model it with complex mathematics. Money has value because we believe it has value. Governments for several centuries have generated debt with the idea that it could be paid back with economic growth, or early on by the divine powers given to a king. The US has generated debt since the War of Independence. This has worked because there is the “good faith and standing” of the treasury. Most large scale economic trends in the US were bankrolled by Federal grants and debt. It works because there is an element of faith behind it all — it is secular religion in disguise. The system got out of balance with Bush’s tax cuts and the wars he waged. Now the people from the same party want to demolish the whole program, which is a bit like trying to play a monopoly game without the bank in the game.
There is a lot of nonsense about economic flying around today. One of them is that capitalism is synonymous with freedom. Ernst Krupp of the German conglomerate wrote a memo in 1930, “We have now put Mr. Hitler on the payroll,” as they agreed to bankroll the Nazi Party. Mussolini wrote that fascism was rule by corporate power. So I think that myth can be dispensed with. In the end, any system of economic power will tend to attract people of avarice and sociopathic tendencies.
I think that a rather strange song by Laurie Anderson sort of really sums up how things work in our world
Catch the last line of the lyrics — it about says it all.
LC
First:
I am sorry, but your answer dodges the issue of presenting “a different sort of economy”.
Of course economics is artificial, so are the scripts running this site. Yet they have a specified and observable function. The question is if this can be improved. I expect not, and your response serve to confirm such expectations.
What we can do is tweak economical processes and constraints, as is already ongoing. There is no inherent problem in that. Which is good for moral and economical concerns such as health care et cetera.
Then:
You respond with a description of your “energy-entropy balance” claim in another comment.
But as I already pointed out, society is far from maximizing entropy. It is desirable to do so, since entropy is a measure of available energy levels. By maximizing efficiency we can increase our resource base efficiently, while minimizing waste.
This is what the biosphere does, by being bathed in an energy flow it can utilize and recycle material, and by doing so it is increasing local entropy more than the non-life planet would.
That doesn’t mean increased resource base, efficiency and recycling is ’emulating ecological systems’. Ecology concern relationships between many populations and the environment, and is much more complex than the simple resource utilization we are concerned with here.
Also, a physics nitpick:
Extrema of entropy characterizes equilibria only. We are discussing systems close to steady-state, so there is no reason to expect a maximum (or minimum). Unfortunately.
Well said that man!
I agree. I think that what I said does imply we should abandon research into the universe, but I didn’t mean that we should abandon it altogether! All I want to do is test the waters of opinion and draw attention to the issue. I will always be fascinated by the the great ‘out there’ and there could be shorter term benefits to science here on earth of continuing focused research, but the big minded quest to understand it all, beyond what is observable will yield nothing of foreseeable benefit.
Your final para really hits the spot and the biggest issue, my hobby horse. This is the paradox I mentioned in the first place; the conflict of interest between the State and the Corporate. This is beyond the reach of science. It is, as I’ve re-commented elsewhere above, a matter of political will and, beyond this, requires a complete change of mindset, which, like any massive research project, needs a gradual preparation, starting with a philosophical but logical approach to the problem; but it has to start somewhere. The political will has to involve finding a way round the ‘Corporaticity’ – that is the reality of the power of multi-national corporations, who sponsor everything and cannot be separated from the state, at least as it currently stands.
So what next?
To be honest I am not terribly optimistic. There is in physics something called the principle of least action. This says that a system evolves in a way so it minimizes a quantity we call the action. In general relativity it turns out this extremization involves a maximal principle. Thermodynamic systems evolve to maximize entropy, and the course taken is the one where the system reaches max entropy or equilibrium in the shortest period of time. In the “battle” between socialism and capitalism I think that from a pure physical perspective the victory of capitalism has a lot to do with the fact it is the economic system which permits the most rapid use of resources and energy, along with rapid increase in entropy. It takes little to see that we are rapidly using up the planet and changing the environment in negative ways, and there is a manic sort of politics in the US that adamantly opposes any attempt to down regulate this. In fact these extremists held the nation hostage in a sense and threatened to cripple the economy permanently to get their way, which they largely succeeded in doing. So the prospect that our species will suddenly get around to seriously addressing these planetary issues seems very faint.
LC
A very worthy response, Icrowell, thank you. I agree with almost all you say here, much of which resonates with me. The only thing that I might disagree with is the increase in entropy accompanying the rapid use of resources and energy. In the short term the building of civilisation is accompanied by a reduction of entropy, increasing order, but in the long term I perceive the sand castle will be reduced to a natural pile of sand by the forces of nature.
Yes, the prospect of addressing these planetary issues does seem faint, but it won’t be sudden; it will not happen over night.
@John Anstie,
you say:
Those individuals wishing to work toward the goal you state as being your desired outcome are already working to win that end. Any not working in that arena due to a different philosophic view than your’s may be switched by your orations or those of another of the same view toward a common end; any wishing to will is what this means in simpler words.
The current view is that the Earth and those common resources (the commons is the usual term) are best distributed in a free market with a level playing field by those wishing to prosper from involvement in the distribution and allocation. The fact that this view does not match well with the real world is a significant problem. Empowering those who do not know what to do with that power is not a good thing for them or any others they contact and influence.
Giving is not the goal, enabling is not the end; charity is not best for the charitable or the beneficiaries. Having is not wanting being fulfilled. Hope, once dashed, generally requires major surgical intervention to breathe once more. Assumptions as to the kindness of all of humanity in general do not ever equate to the ‘individuality of a mob of humans wishing and working for what they wish’.
Asking folks to devote hours of their day toward a goal they do not share is not only a troubling idea, it is fruitless in a free market as that individual will change jobs as soon as possible, sooner if the desire outweighs the sensibilities of that person.
Asking governments and organizations to restrict additional births has been viewed as inhumane and a less desired solution with the goal of a voluntary choice of some individual(s) to not bear children. Selecting some random 10% of the world population regardless of age, sex, marital status, religion, eye color, etc., and removing any and all ‘Right to Life’ from them is also seen as inhumane –however if individuals step forward and ask for this choice would you give it to them. Restriction of birth within national, racial, religious groups, etc., is akin, in their eyes, to killing the dream of that group.
One argument is “The population increase needs to reverse, rapidly, the resources are finite and manageable for a smaller and better trained peasantry.” One addendum is the speed of that reduction — it needs to foreshorten several generations. Who is to be the arbiter, who is to win the goal of fair and equitable distribution of life never-born to these groups.
You are asking that some individuals make choices for other individuals, both the living and the never-born. The ethics of that choice will always be questionable to some group, nation, race, creed, etc., and can not be enforced short of the restriction of other rights by those NOT being asked to surrender the ‘Right to Life’ they might have under this argument so as to enforce the will of the many over the will fewer, of the other than many in other words. Who will represent them to the rest of us, and how can they look those left alive in the eye?
As much as we may wish for a better world and work toward that outcome the brutal facts will deny that fruition.
Sorry I got so long, I actually shorten this by half.
Mary
Don’t make excuses, in the context of my comments these are short!
Mary, couple of brief points. The length of your answer tells me you have have read too much into my questions, missed the ‘paradox’ and elicited meaning that is not there.
I deliberately avoided the issue of population control, simply because it is about as big an issue as humanity will ever have to deal with and I believe it will self regulate, anyway.
I did not claim that there is no ET life out there, I just said we will never find it – and even if we did, assuming that it was able to communicate itself to us and we to it, what on earth (if you pardon the cliche) would we do about it, with it? But this is not the point; my point is that we are scratching the surface of knowledge of what is out there, simply because we cannot truly observe a vast majority of it; it is the sheer scale of the universe that militates against.
Sorry to shatter the scientists dreams, but let’s get a grip on reality here on earth.
The reality is that your claim (“we will never find it”) is erroneous and based on a strawman, see my comment addressing that above.
I leave it for the reader to judge who has the better “grip on reality”.
I agree that the topic is inappropriate in a thread not geared for it.
The only proper response I can give to this is that it is a false suggestion based on a false argument.
– In the extreme, it is a false choice suggestion, because we can do both. Hence a wrong argument.
Unless you acknowledge that there are mere resource constraints, ROI factors, and analyze those.
– And in fact we do both.
No one is running away. Especially if we are trying to promote science, which is acknowledged to be cumulative and give good (perhaps best) ROI for socity prosperity.
But that is another case, of exploration and exploitation.
And I agree with other commenters, no one thinks there is a solution to urgent local problems in that. We may or may not supplement our local resource base, but that is it. We can’t possibly import or export material or people sufficiently effectively to be helpful.
However, this is a good tie in to the larger and more immediate topic of the article here. lcrowell saw that. To give his reply a perspective, I can plug yet another model I mentioned below:
Outer space is in fact an answer to the question raised in the first photo: “where are they”. The so called Fermi question has a natural answer in what will happen as we expand out into space.
As soon as we get to the Oort belt, we will meet an effectively infinite resource base – comets supplying habitats, volatiles, organics, metals, fissiles/fusables, and usable as vessels.
When that happens we will eventually stop wasting our resources on expensive visits to planets deep in gravity wells. In fact, once lost such a capacity would be hard to develop again.
So a feasible answer to “where are they” may be “they are out there”.
An Oort cloud migration would take on the order of age of the current universe to disperse from one side of the Milky Way to the other with chemical rockets.
And such a society wouldn’t broadcast. It would soon speciate and fragment.
Torbjörn, I am pleasantly surprised at the volume of response to my comment, but I have to say I interpret your response as a bit of a diversion from my questions; by this I mean you have not addressed the question with enough clarity. And, yes, this may not be the forum to raise this point, because you are all too deeply immersed in a complex process of hypothesis and scientific analysis. My comment does not need to to be over analysed by scientists at this stage – and I’m assuming you are inclined that way. This question, the paradox, will only be solved by scientists, once there is a political will to do so. Then ROI, and all the other practical requirements and commercial motive become almost irrelevant.
John, the volume of my response to your question goes until “urgencies”, so is no longer.
It was a specific short reply to your suggestion that there is a “paradox” – it is not. I have not used science in any of this, nor an “over analyze”, I pointed out where the connection to real concerns lie.
The answer to the social question is similarly short, so I can as well put it up:
If one acknowledge that this is a question of best return on finite resources, as always, instead of declaring that “all” resources goes to this or that:
NASA claims that return on space investment is ~ 50 % (IIRC), and the usual figure is something like ~ 20 % (IIRC), the best way to address outstanding concerns on Earth is to increase the returns by investing in space. That takes care of exploration and exploitation.
The same principle adheres to science which is integrative. By expanding it in space, the overall return will be maximized.
There is nothing odd in this, complex systems are expected to have non-linear responses, not obeying “common sense” patterns.
Thanks for your further replies, Torbjorn.
The following will attempt to pull together all the different threads of comments above and below this point, which relate to my original input.
This is all very interesting, if distracting! I do feel we are talking on completely different levels… yours paying little regard to political will and social (as opposed to apparent economic) interest and mine with little interest in the veracity or otherwise of the scientific arguments, not because I don’t want to understand them, not because I don’t have an interest in them myself, but just because the reality of the socio-political-economic status of the world makes them irrelevant at the present time. This is simply because the latter cannot stand on their own without the former (i.e. without political will and corporate sponsorship there will be no work for scientists in the area of space exploration). All I can say here, Torbjorn, is enjoy it while ye may; and indeed you may and I hope you will for the rest of your life, but future generations may well not be able to.
On the subject of ROI and economic justification: you have missed my point. I said “ROI…etc. become almost irrelevant”, whether or not NASA can “claim” a high ROI from space exploration is of no consequence; there’s no point wasting time trying to verify their figures, because the issues on earth, to which I originally referred, will critically dictate what research can be continued.
Another point on the “side issues’ to which you refer above, in particular the methods you list for observation of habitability and life itself… “…to various distances” I would simply ask with what statistical confidence? But, regardless of that question, again I think you have missed the point I made, which is my claim about ET life that “we will never find it”. I never said that there isn’t other life out there, just that we won’t find it.
To put the record straight, throughout my education, physics was always my favourite subject; the logic of its laws are so ingrained. Consequently, “The Laws Underlying The Physics of Everyday Life…” (good article by the way) always inform the logic I adopt in solving many everyday physical problems in my life; it is of enduring value and the high level physics that you guys use to examine the almost un-examinable is admirable. So, don’t take anything I’ve said as a slant against honest science and honest scientists i.e. you guys, but my stance on the justification for space research stands, regardless. My position, my ‘reality’ if you like, in the latter stages of my life are now focussed very firmly on the socio-political rather than the engineering-scientific aspects of life. The two join up in the middle somewhere, but in this arena, it is hard to see where – and please don’t waste any of your time trying to answer this one!
Finally, your comment about who has a grip on reality. I suppose I could take offence at that, but I don’t, because I don’t think you intended it so. We are all wired differently, sometimes with very minor differences, sometimes far greater; but differently nonetheless and “vive la difference” many would say. Ask the mother with her dying child in her arms in famine-torn Africa what is her take on reality; ask the child of drug addicted parents living without hope in the ghetto of any city of the world; ask the well educated, well connected and privileged son or daughter of a banker what is their view of reality; all will give you radically different answers. These differences in our perceived realities can make the world the diverse and rich tapestry it is, but, perversely, it could also be our undoing, because without a common perception of what is needed, how we resolve the problems we face, the inequalities in the distribution of the world’s assets amongst its populations, a vast majority of us will sooner rather than later suffer the consequences in many ways that will be a shock to the system; and that includes whether you get paid any kind of living wage to do your research; whether I get a pension or not!
The paradox to which I originally referred, is here. The political and the inextricably linked corporate will to address these issues depend entirely on whether or not the relevant individuals, who have the power and influence, wish to diminish the material motive in favour of a more equitable solution. And herein lies the rub.
http://tinyurl.com/Distribution-of-Resources
Now on to the side issues, which are more appropriate here:
As for feasibility, Uncle_Fred discuss that. Observational methods are developed as we speak.
Currently it seems we will be able to observe habitability from:
– Indirect (models) and direct (emitted light) temperature measurements
– Atmosphere composition (emitted and reflected light spectra)
– Water (specular reflection; reflected light cloud absorption)
We can observe life from:
– Thermodynamical imbalances in atmospheres (metabolism)
– Thermodynamical imbalances in atmospheres (photosynthesis)
– Vegetation (reflected light modulation from continent wide forests)
– Civilization (night light emissions)
Out to various distances.
The reason we would like to do that is because it informs us on:
– a question that has been primary in many societies for a long time (“are we alone”)
– chemistry and environment of life
– frequency of inhabited vs habitable worlds
which constraints in turn informs us on biology of abiogenesis.
As before, science stimulates science, ultimately progress will help us with societal concerns.
This is complete a strawman of science.
That is perplexing since you start out be describing yourself as familiar with science.
Surely any scientist would know, and promote, that “The Laws Underlying The Physics of Everyday Life Are Completely Understood“, as physicist Carroll puts it.
The reason it works out that way is because testing eliminate erroneous fact and theory by taking advantage of uncertainty (quantifying it). Observably then the process converges.
Nor is there a principle problem here. The stack of theories and facts allow for ever more reach. Recently we have started to probe planck scales it seems. (By timing and polarization observations of supernova photons.)
On the other hand, we have finite resources and inhabits a localized volume in a large universe. It is preposterous to claim that just because we likely _can_ understand it all in principle, we will eventually _do_ so in practice.
As the lady says, “it is sweeter to keep some secrets”.
Now on to the side issues, which are more appropriate here:
As for feasibility, Uncle_Fred discuss that. Observational methods are developed as we speak.
Currently it seems we will be able to observe habitability from:
– Indirect (models) and direct (emitted light) temperature measurements
– Atmosphere composition (emitted and reflected light spectra)
– Water (specular reflection; reflected light cloud absorption)
We can observe life from:
– Thermodynamical imbalances in atmospheres (metabolism)
– Thermodynamical imbalances in atmospheres (photosynthesis)
– Vegetation (reflected light modulation from continent wide forests)
– Civilization (night light emissions)
Out to various distances.
The reason we would like to do that is because it informs us on:
– a question that has been primary in many societies for a long time (“are we alone”)
– chemistry and environment of life
– frequency of inhabited vs habitable worlds
which constraints in turn informs us on biology of abiogenesis.
As before, science stimulates science, ultimately progress will help us with societal concerns.
This is complete a strawman of science.
That is perplexing since you start out be describing yourself as familiar with science.
Surely any scientist would know, and promote, that “The Laws Underlying The Physics of Everyday Life Are Completely Understood”, as physicist Carroll puts it.
The reason it works out that way is because testing eliminate erroneous fact and theory by taking advantage of uncertainty (quantifying it). Observably then the process converges.
Nor is there a principle problem here. The stack of theories and facts allow for ever more reach. Recently we have started to probe planck scales it seems. (By timing and polarization observations of supernova photons.)
On the other hand, we have finite resources and inhabits a localized volume in a large universe. It is preposterous to claim that just because we likely _can_ understand it all in principle, we will eventually _do_ so in practice.
As the lady says, “it is sweeter to keep some secrets”.
While there are many interesting comments made here, they all skewed by our quite naturally anthropocentric world-views.
The evolutionary model advanced in “The Goldilocks Effect” (free e-book download from my Unusual Perspectives website) takes a much wider view and provides a quite different approach to phenomena related to biological (and other) life processes.
Incidentally, (Wezley Jackson) my first and related work “Unusual Perspectives” really DOES include baked beans and ETI in its subject matter. That, too is a free download.
Apropos The Monty Hall problem I think we can agree that the crux of the different interpretations of residual probability hinges on the agency attributed to him. With this agency the argument for changing doors is fair, irrespective of the number of doors. If, however, the doors were instead opened by some purely random means the probability reduces to 1/2 for either remaining door.
So, as so often happens, perhaps the protagonists are really arguing at cross purposes?
It doesn’t seem to be a textbook or review. Instead it looks to be the kind of “personal theory” TOE that litters the web and that used to be banned here. Am I right? (Unfortunately no synopsis is offered, so it would take quite some effort to ascertain relevance.)
[Btw from the site, it is quite impossible “to offer the odd olive branch to readers of a religious disposition” from the perspective of science; dogma is the opposite of revisable fact & theory!]
I do my best to catch personal theories when possible. If you see any blatant violations Torbjorn, feel free to email me: [email protected]
That e-mail address sounds rude!
That sounds like a plan!
The rationale behind “offering the odd olive branch” to the religious” was to perhaps draw some of the less committed towards evidence-based stand-points.
Essentially provision of a “slippery slope” towards reason, an alternative to the “bang them over the head with a hammer” tactic that has been adopted by, for instance, Richard Dawkins
Since writing “Unusual Perspectives”, however I have become increasingly cynical about the efficacy of either approach and suspect that both, as suggested by Torbjen, are essentially just “pissing in the wind.”.
Accordingly I have taken a much more hard line approach in “The Goldilocks Effect”.
Actually I have a strong hunch that, in general, humor may be. the best weapon for fighting superstition. The work of Monty Python, Penn & Teller and Tim Minchin spring to mind.
Interestingly the other, essentially Ad Hominem, remarks by Torbjorn provide no kind of substantive discussion whatever. This kind of behavior is sadly very common in blogs, where many contributors seem to have very limited attention-spans and unable to comprehend any argument that occupies more than a few paragraphs.
My writings in no way represent a TOE and, indeed, I have very serious doubts that a TOE is achievable.
What they do support is the notion that the basic evolutionary patterns and directionality exhibited in biology are contiguous with other processes extending from (at least) stellar nucleosynthesis right through to the currently observed evolution of technology. Evidence is provided to support this non-anthropocentric stance.
As to the lame “Personal theory” dig – surely nearly all the comments made on this and other blogs are “Personal theories”.
The world would be a sad place without them.
At the risk of sounding whiny, not so long ago Bayesian analysis may have been helpful detecting exo-planets in data from another famously canceled telescope… Linear and Bayesian Planet Detection Algorithms for the Terrestrial Planet Finder. Sigh
I want to just add my two cents worth since the probability of life and, more specifically, ETI has been a subject near and dear to my heart for many years.
I am 100% certain that not just life but ETI exists elsewhere in the universe. The universe is simply so large that in respect to a human being’s understanding of such things it is infinite. I understand that according to modern science, the universe is not infinite, although I’m still not convinced this is the case. There are just too many unknowns about it to be sure.
Regarding the existence of life and ETI elsewhere in the universe, we have only 1 example to use as statistical evidence – the planet Earth. Does this mean we shouldn’t even hazard a guess? Of course not – it simply means that our evidence is severely limited and we should be prepared to admit that whatever conclusions we come to could be proved wrong in the future.
Looking at the history of life on Earth (as far as we understand it), our planet has been habitable for approximately 3.6 billion of its 4 billion year life, if I remember correctly. Further, complex life (life more complex than bacteria) has only been around for about 600 million years and humans or their immediate ancestors for only a few million years, let’s say 5 million years for the sake of argument since this is a very subjective time period. Again I am repeating this based on memory so please feel free to correct me if I’m wrong. AFAIR, the average estimate for how long the Earth will remain hospitable to human life as we know it is around 500-750 million years, with all life becoming extinct around 1-1.5 billion years from now. Using these numbers, the Earth’s total time frame for habitability for any kind of life is approximately 5 billion years. This works out to life first appearing after approximately 18% of the Earth’s total habitability time frame had elapsed. This seems rather encouraging as it pertains to the possibility of life elsewhere in the universe and, although somewhat biased, I personally believe life is abundant in the universe. As far as human life is concerned, we (or our immediate ancestors) first appeared after approximately 89% of this total habilitability time frame had elapsed. To relate that to a human life span, we did not evolve on this planet until our planet was 89 out of 100 years old. In other words, our planet Earth was in its old age when we finally evolved. This is not very encouraging to me and leads me to believe that ETI as we would understand them are not very common at all.
I always look for information that will re-energize my desire to believe that not only do ETI exist elsewhere in the universe but that our galaxy alone is chock-full of them. Of course, how can this be, when SETI has not detected even 1 confirmed signal from any ETI? One paper I read a few years ago was very intriguing. I looked for it on the web today and could not find a reference to it but the gist was something like this. Due to the property of radio waves to lose energy (through dispersal) and degrade over distance as well as when they come into contact with matter, even radio waves from as nearby as the Alpha Centauri system may not be recognizable as such by the time they reach Earth. The author stated that these waves would still reach the Earth but may not be recognizable as anything other than noise and may, in fact, be intermingled with and contained within the cosmic microwave background. Personally, I am not a big proponent of the big bang theory and thus would like to think that the CMB is nothing more than these degraded radio/energy waves from the countless ETI civilazions surrounding us. That obviously was not a part of the paper I was referring to but it would really be nice, right?
Anyway, please all feel free to comment and correct any of this post you wish to. FYI – I am what everyone would consider a layman with regards to most of the subject matter found on UT. I did attend Texas A&M University for 2 years in the Aerospace Engineering program and have some educational experience in modern physics, advanced mathematics, and astronomy/cosmology but am by no means an expert.
Thanks all – Mike F.
I will brave yet another response in this already long thread.
– I would say you get the simplest baseline models for statistics of abiogenesis and intelligence evolution correct. (I comment on those below, FWIW.)
– The SETI description is my understanding too, FWIW.
– The physics is odd:
That was true in the old big bang cosmology, or at least there was little information on it.
However the decade old standard cosmology that replaced it changed all that. Putting inflation before a roughly freewheeling big bang expansion, and having dark energy accelerated expansion dominate after the freewheeling phase, made it explicitly forward eternal.
Of course people like to ponder physics that may change this, but you have to introduce it into the current cosmology.
It also opens up the symmetry of potentially infinite space, because space looks flat. The simplest model is precisely that. As above you would have to introduce physics to remove it.
(And similarly the simplest model of inflation may be backward eternal, which completes a symmetry time vs space. The lone symmetry breaking would be the expansion/forward direction of time.)
The isotropy of CMB makes discrete and localized sources impossible AFAIU. The multipole behavior of the spectra makes later time radio sources impossible I think, it would be too much finetuning.
CMB originated in thermal radiation that permeated the early universe.
Conversely, if you remove the CMB as predicted by something else than the result of expanded thermal radiation, how would you explain the absence of thermal radiation from the early, denser, hotter universe? You still observe cosmological redshift, so have an expansion.
Thank you for your response. I very much enjoyed reading it but I believe it points out that in my efforts at brevity, I did not explain my thoughts with enough clarity.
When I stated that the universe is not infinite I was generally stating that in our current accepted understanding of the universe as I understand it, the universe had a beginning and although it will still exist, will also have an end in the final form resulting from the laws of thermodynamics where all energy has dissipated in the ever greater expanding universe. Of course this does not bring into the discussion possible multiple universes, branes, etc.
One question for my own clarity of your response. Does your statement that the dominating accelerated expansion of the universe makes it explicitly forward eternal mean just that the finite universe is expanding in such a way that we will never know it to be anything other than infinite? If I’m way off here please explain that further – I would appreciate it.
Lastly, regarding your comments about the CMB and its representation of the thermal radiation that permeated in the early universe, when I stated I was not a big proponent of the big bang theory, I should have expounded on that by stating that I’m not sure there ever was an early universe. So if you make a very crazy assumption that the universe is in an expanding phase of a repeating cyclic oscillation and will eventually slow down then repeat, wouldn’t you be able to take the CMB representing this early universe thermal radiation out of the equation and then posit other hypotheses as to the reason for the existence of the CMB?
This is not a personal theory (moderator!) :). It is simply my own personal musings of how things may be different than we generally perceive.
Thank you so much for your response.
Mike F
Thank you for your response. I very much enjoyed reading it but I believe it points out that in my efforts at brevity, I did not explain my thoughts with enough clarity.
When I stated that the universe is not infinite I was generally stating that in our current accepted understanding of the universe as I understand it, the universe had a beginning and although it will still exist, will also have an end in the final form resulting from the laws of thermodynamics where all energy has dissipated in the ever greater expanding universe. Of course this does not bring into the discussion possible multiple universes, branes, etc.
One question for my own clarity of your response. Does your statement that the dominating accelerated expansion of the universe makes it explicitly forward eternal mean just that the finite universe is expanding in such a way that we will never know it to be anything other than infinite? If I’m way off here please explain that further – I would appreciate it.
Lastly, regarding your comments about the CMB and its representation of the thermal radiation that permeated in the early universe, when I stated I was not a big proponent of the big bang theory, I should have expounded on that by stating that I’m not sure there ever was an early universe. So if you make a very crazy assumption that the universe is in an expanding phase of a repeating cyclic oscillation and will eventually slow down then repeat, wouldn’t you be able to take the CMB representing this early universe thermal radiation out of the equation and then posit other hypotheses as to the reason for the existence of the CMB?
This is not a personal theory (moderator!) :). It is simply my own personal musings of how things may be different than we generally perceive.
Thank you so much for your response.
Mike F
This subject hinges on observation of habitability and appearance of earliest life. Unfortunately there doesn’t seem to be any recent review on that topic, that I am aware of. Therefore I will attempt a synopsis.*
Observation of time for earliest life is done by two methods, fossil methods and molecular clock methods.
*** Fossil dating ***
This is the most rigorous of the two.
* Assured dating *
Fossils provides likely assured dating. The currently most popular date for assured early life seems to be ~ 3.5 Ga.
It includes two locales, Australia and South Africa. Those who criticize the Australia stromatolites and microfossils usually promotes South Africa finds instead. But there is one Australia stromatolite find which, to my knowledge, stands fairly well. In any case, one or two fairly good observations.
* Tentative finds *
– Earlier putative observations are trace fossils. A cluster of carbon isotope fractionated minerals goes back to ~ 3.85 Ga.
Carbon fractionation measures δ 13C difference in the 12C/ 13C ratio. Most minerals scatter ~ – 5 – 15 o/oo compared to the reference.
Abiotic Fischer Tropfsh processes, that can happen in hydrothermal vents say, takes CO2 and H2 over CO and COH to -CH chains. It results in a rather precise – 30 o/oo addition to the background fractionation.
Various cellular metabolisms add too. Most is added to the background, ~ – 45 o/oo, by the common glycolysation that is a key point for both catabolic (breaks molecules and gives energy) and catabolic (takes energy and builds molecules) processes.
The oldest Akilia find shows inclusions that clusters ~ – 10 o/oo and ~ 50 o/oo. The latter is most easily predicted as result of metabolism.
Criticism given is that those are metamorphic carbon minerals. I am naive on what contribution metamorphism adds in fractionation as light carbon would preferentially leave the mineral one would think. However, an alternative prediction is a previous source of light carbon.
– The earliest published possible trace fossil is the Jack Hill zircon diamond inclusions going bacj to ~ 4.25 Ga. They too cluster as above, and here a light carbon reservoir has been explicitly mentioned.
– An earlier set of trace fossils may be the Nuvvuagittuq greenstone belt that can go back to ~ 4.28 Ga. This is not published, but apparently there have been ideas of them having traces of an early sulfur cycle.
* Habitability *
Jack Hill zircons dated to ~ 4.35 Ga shows formation with presence of liquid water.
*** Molecular clocks ***
* Standard molecular gene clocks *
These gives latest dates, and need fossil or geological events for calibration.
They are controversial. Earlier methods could scatter ~ 20 times (!) the fossil dating. New methods that circumvent the problems by being able to include many fossil and geological time references have been developed.
However, the so far given latest date of earliest divergence of ~ 4 Ga is made with old methods.
* Gene family clock *
This is another toy model of mine. It derives from the fairly steady gene family event rate (sum of birth, transfer, duplication, loss) shown by early work. [“Rapid evolutionary innovation during an Archaean genetic expansion”, David et al, Nature 2010.] It ranges from ~ 0.4 events/My to ~ 1.6 events/My.
They assume a date for the LUCA, from the trace record, of ~ 3.85 Ga. The model is self-consistent however, and accords with dates for end of Late Heavy Bombardment (the Archaean Expansion, AE) and atmosphere oxidation (electron transfer redox metabolism).
Moreover, before the AE there is only a steady gene birth.
Let us assume that steady rate of ~ 0.4 events/My. Their LUCA estimates ~ 180 gene families. (Of course it is now estimated that the LUCA had ~ 3 000 – 4 000 genes, comparable to todays prokaryote average.)
This gives a latest date for the first gene family of ~ (4.55 – 3.85)*103 – 183/0.4 ~ 200 My from Earth accretion. Or ~ 4.31 Ga.
This clock date slips comfortably in between presence of water and first putative fossils.
———————–
Since I have not enough time, I will not provide all pertinent references at this time.
Of course, the brouhaha over Bayesian Analysis is because it is not just an application of Bayes Theorem, so I’m not sure why the Monte Hall problem is relevant.