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Wolfram Alpha's take on the Drake Equation
- thebooktocome 16y agoIf I had a buck for every distinct interpretation of values for the Drake Equation, I wouldn't need to grade homework for a living. Whether this is a comment on the Drake Equation or my salary is an exercise left to the reader :)
- PixelRobot 16y agoThat's some optimistic data there.
- danparsonson 16y agoThat's what I thought - "average number of Earth‐like planets per star with planets: 2"... really?
- deutronium 16y agoI'd like to know where that value comes from, is there any scientific basis to it?
- PixelRobot 16y agoIt seems to be just speculation. There's not much data you can use to guess those numbers with the current scientific knowledge.
- rflrob 16y agoWhen the equation was first proposed, I'd guess they assumed Sol is an "average" solar system, and given that we have Earth, which is by definition Earth-like, and Mars, Venus, and several of the Jovian moons, which could all fit a suitably loose definition of "earth-like", Drake might even have thought he was being conservative.
- jawns 16y agoThat raises the question: What's the least-optimistic combination of data that yields at least one communicating civilization?
- asmithmd1 16y agoJust change "fraction of Earth‐like planets that develop life:" from 1.0 to 0.1 and you get 1 That guess could be off by many orders of magnitude as we have exactly one data point right now
- tordirycgoyust 16y agoMore interesting to me is the chance of intelligent life variable. A couple of months ago on Ars Technica iirc, there was published a writeup on a paper on how macro life (much less intelligent life) requires something analogous to mitochondria for the cell to be large enough to handle that level of complexity (the problem being caused by the geometric relationship between volume and surface area). the paper goes on to say that the chances of one organism entering another and them then entering a mutually beneficial symbiotic relationship as being astronomically low (it is, however, a function of time, but Ars implied (iirc) that this doesn't noticably help the Drake equation the chance is that low). Based on this I would adjust Fi by a couple dozen orders of magnitude
- eru 16y agoOh, the chances of such symbioses aren't too bad. They happened many times. See Mitochondria, Chloroplasts, perhaps Cell nuclei, the retro virus that's incorporated in our genes that make mothers' immune system not reject the fetus. (See https://secure.wikimedia.org/wikipedia/en/wiki/Endosymbiosis https://secure.wikimedia.org/wikipedia/en/wiki/Endosymbiosis and https://secure.wikimedia.org/wikipedia/en/wiki/Endosymbiotic_theory https://secure.wikimedia.org/wikipedia/en/wiki/Endosymbiotic... for more.) On a scale broader than single cells there are around 80% of vascular plants and their symbiosis with fungi, the bacteria in our guts, the worms close to black smokers, certain sea cucumbers that absorb algae and live off their photosynthesis, and much more.
- bellaire 16y agoThese are the values originally used by Drake et. al. when they proposed the equation in 1961. Many were outright guesses. Nevertheless, 50 years later, we still don't have much better guesses, but this may change soon for proportion of planets with stars (is probably higher) and stars with earthlikes (coming soon).
- rblion 16y agoSeems low considering Milky Way has between 200,000,000,000 and 400,000,000,000 stars.
- eru 16y agoBut a year is not that long, either.
- aseem 16y agoShouldn't the answer be 42?
- leon_ 16y ago2 earth like planets per star with planets? that's bold.
- ceejayoz 16y agoDepends on your definition of "Earth like". Mars would fit some definitions - rocky, atmosphere, water present.
- PixelRobot 16y agoI assume "Earth like" in this context means planets that resemble the only planet known to hold life at least enough to be capable of holding life themselves. The problem is we don't even know what that means exactly. It's also assuming that life can only exist in "Earth like" conditions. Also, if Fraction of Earth‐like planets that develop life = 1 and Mars is an "Earth like" planet, are they assuming life evolved in Mars too or something?
- exit 16y agoin that case, value of 1 for "fraction of Earth‐like planets that develop life" is odd since we are far from confident that life ever developed on mars.
- rbanffy 16y agoWhat we call atmosphere in Mars would pass for a very good vacuum in a classroom. Life could develop on a Mars sized body, but then the star would have to be far less active than our sun (so that the planet could retain a reasonable atmosphere)
- asmithmd1 16y agoI think this is bolder: "fraction of Earth‐like planets that develop life: 1" For all we know that could be .001 or .0000001
- rflrob 16y agoI'm okay with the Field of Dreams interpretation of astrobiology: "If you build it, they will come", so to speak. All you need is for life to take hold once and it'll take over a planet in just a few billion years. Of course, my own hunch is that suitable chunks of rock (planets, moons, etc) are somewhat more rare than the default value[1]. [1] I plugged in .1, among other variable changes. On the other hand, I got the number of communicating civilizations = .02, so either I'm too pessimistic or we're just really, really lucky.
- geuis 16y agoIts interesting that Alpha has the equation baked in. What would be more interesting would be to see a regularly updated version of this with the latest cosmological data coming in from telescopes like Kepler. Over the next 3-5 years, Kepler is going to be finding Earth-size planets that exist in their star's habitable zones. For those not familiar with how Kepler is finding planets, I'll explain. Basically, Kepler looks for planets transiting in front of their stars. The telescope watches for dips in the star's light. If the planet has an atmosphere, in some cases it can even get an idea of some of the gases from the light. The reason that astronomers aren't expecting to find Earth-size worlds in the habitable zones is that they have to wait for several transits to know for sure they've seen a planet. The reason that most of the planets found to date have been gas giants orbiting very close to their stars is that it only takes a few weeks or months for them to transit the star several times. Astronomers can see one transit, but have to wait for a 2nd to hypothesize a planet is found, and have to see a 3rd or more transit to verify the planet is real. So Kepler has likely already detected suspected Earth-size planets in habitable zones around at least a few stars. However, the telescope has to watch for several years to confirm the transits. Imagine an astronomer in another solar system that has seen Earth transit the Sun. They would have to wait 3-4 years to see Earth transit the Sun several times to confirm our existence. Edit: Meant to include this earlier. There are multiple ways to detect exoplanets, including the transit method. http://en.wikipedia.org/wiki/Methods_of_detecting_extrasolar_planets#Transit_method http://en.wikipedia.org/wiki/Methods_of_detecting_extrasolar...
- RomP 16y agoThis is something I have hard time understanding. Most of the stars are having star flares most of the time. If they're like our Sol, they have periods of high and low flares activity, but within the periods the pattern is random (i.e. noise). Presumably, the change in luminosity caused by a random flare is bigger than by a planet transit (remember transit of Venus?). So how are they filtering the noise out?
- jerf 16y agoThere's no quick answer to that question, unfortunately, because if you want something other than handwaving the answer is to go learn about the basics of signal processing. But in short, the signature of a set of random flares and a regular crossing of a planet are sufficiently different that they are easily separated by the correct tools, the frequencies are totally different.
- Adrock 16y agoWhat's really depressing is if you assume the number of communicating civilizations is 1 and make average lifetime of communicating civilizations be the free variable.
- khafra 16y agoYou might be interested in The Great Filter, although it probably won't make you feel any better: http://hanson.gmu.edu/greatfilter.html http://hanson.gmu.edu/greatfilter.html
- DanielBMarkham 16y agoOne of the things I love so much about the Drake equation is how it's all so much bullshit. Before you downvote me, I think it's a great equation and I don't have problems with folks using it. As long as you know what you are doing. really, think about it, all it actually says is that there is this list of things that we feel have to happen in order to determine communicating civilizations, and given any random set of probabilities for a list of things, you multiply them together to get an aggregate answer. It doesn't address whether the list is complete, or overly complex, or mis-stated. The numbers provided are juts best guesses. It's just "multiply a bunch of numbers together and get a new number" I love it. It's definitely not science -- yet it has this cool-looking formula involved. It also has a powerful impact on folks who use it. Drake is really cool in that it gets people thinking about how likely ET is. For that, it's a wonderful tool. But at its heart there's really not much there. At least yet. Perhaps in the future we'll have some solid survey results to put in, especially with Kepler online. Can't wait to start seeing those results coming in.
- dantheman 16y agoI really dislike the drake equation because it's the epitome of bad science -- when someone enters value for the variables they have no idea what is reasonable, absolutely no idea -- is it 0.1 or 0.0000000000000000000000000000001 we have no way of knowing. Though I do like how it gets people to realize how small and insignificant we are in the grand scale that is the solar system, the reasoning we take to get there is fundamentally flawed. We use numbers that have everyday meaning to us, and of course it spits out nice results; this is flawed reasoning since we have no basis to think those numbers are even remotely correct. In general, I just think it's sloppy thinking that takes advantage of deficiencies in human thinking -- it's a magic trick.
- DanielBMarkham 16y agoI really tried to be even-handed with my comment -- I didn't want to sound like a troll -- but you are completely correct. In fact, the Drake Equation is a religious statement. That is, it is a creative speculation using commonly understood symbols to that which are completely unknown to us. It's the same as a couple of cavemen sitting on a hill talking about thunder as being large rocks falling from a cliff in a faraway valley. It makes sense, it fits in with what we know, but it's really just a bunch of guesses connected with symbols that, based on context, we feel social approval towards. It's a mind-hack. And a very nicely executed one at that. The reason I didn't use the "R" word, religion, is that folks see that word and stop thinking. They give you an instinctual answer. No way! I'm not religious! etc. The Drake equation basically says what anybody who has looked up at the night sky knows intuitively: there are a lot of stars out there, and it's extremely unlikely that we're all by ourselves. It just does it in a way that makes us feel like we're receiving some sort of imparted scientific wisdom, instead of what it really is: creative speculation. In that sense the formula itself may be total bullshit scientifically, but what it tells us about how science and religion play with each other is very important. People look at it and just feel that there is some truth there, and there is, but it's not the same kind of truth as f=ma, although both statements are expressed mathematically and have the same air of seriousness around them.
- exit 16y agonote that the drake equation gives the number of currently communicating civilizations. if you think there are 10 communicating civilizations now, each communicating for 10000 years, then there should have been quite a few such civilizations in the 13000000000 year history of our milky way galaxy. if the parameters provided apply for 1% of the milky ways history, we would expect 13000 communicating civilizations in total. i would imagine any communicating civilization lasting 10000 years would also develop self reproducing space probes, thus becoming a permanent feature.
- narag 16y agoWhen first stars appeared they were made out of hydrogen. It seems that you have to wait for second or third generation stars (formed from rests of previous defunct stars) in order to have heavy elements that would form planets and allow life. We could be the first, or one of the first civilizations in the galaxy. Trouble with the equation is that it does make nobody happy. As we are knowing better some factors (like how many stars have planets) it seems that life should be everywhere. But it's enough that one the still unknown unknowns is worse than we think, to make the density as low as a few dozen civilizations in the galaxy. That's too far for us to communicate in a 10.000 years scale. BTW, I find this 10.000 number is cruft from cold war era. Some people love the extintion idea, not sure why.
- btilly 16y agoThe best response to the Drake opinion, IMO, is Tipler's point that if even one civilization created and sent out a von Neumann machine just a million years ago, they'd be here by now. So the fact that we don't see them all over suggests that they do not exist at all. See http://en.wikipedia.org/wiki/Von_Neumann_probe#Implications_for_Fermi.27s_paradox http://en.wikipedia.org/wiki/Von_Neumann_probe#Implications_.... It should be noted that if our civilization survives another few hundred years, we are likely to send out von Neumann machines.
- Confusion 16y agoWe are? I find that a rather bold assertion. The main problem of the von Neumann machine is gathering and transforming enough materials on its own. If we need enormous amounts of ore and factories to do that, so does the machine. It would need to be mindboggingly huge, also because it needs enough fuel to reach new sources. A tiny machine won't work, because it can't refine it's own materials. Really, the practical problems are being hugely underestimated.
- random42 16y agoWhy the search of ET Intelligence is of any significance for mankind (or even science for that matter)? Even if we assume that ET life exists, in all likelyhood, after spending billions of trillions of dollars, we may get to know that ET exists (assuming they do), are thousands of light-years away from us. Apart from the curious "are we alone?", does answering this question, has any positive/productive outcome?
- jbri 16y agoI hear that "transistor" thing is pretty much a waste of time too. A scientific curiosity at best. It's not necessarily about the destination, the stuff we find on the journey is valuable in its own right.
- varjag 16y agoWe are nowhere near billions of trillions of dollars spent on SETI (I'd venture to guess it's in 100s of millions for all these decadesat best), but. Finding an ET would be event of scientific significance that can hardly be compared to anything else. Perhaps a manifestation of God's existence comes closest.
- bufo 16y agohttp://xkcd.com/384 http://xkcd.com/384
- PostOnce 16y agoThe Drake Equation's most telling fault, for me, is the "average lifetime of communicating civilizations". The default is 10,000 years. That results in 10 civilizations. A 1,000 year lifespan means there is only 1 civilization, and a 100,000 year lifespan means there are 100 civilizations. As if we have any idea how long a communicating alien civilization would last. We don't even know how long we will last, and aliens would be completely different to us.
- iwwr 16y agoA quick thing to notice, if you fiddle a bit with the variables, you can get the answer "1" to the number of civilisations in our galaxy. Just decrease the probability of life or intelligent life. After all, it took 3 bn. years before the first multicellular life developed on Earth and 1bn. years for intelligence to develop afterwards.