Planet Four Talk

The Drake Equation

  • wassock by wassock moderator

    Just caught a rerun of this months sky at night. Anyone know of a good source which discusses the detail of the individual Drake equation factors, particularly Fi and Fc?

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  • p.titchin by p.titchin in response to wassock's comment.

    Hi Wassock, I thought that the whole point of the Drake Equation was that as it is not possible to even guess at what the factor values might be , the equation is not solvable. It has solutions from zero to infinity, but is still a useful 'mind game' to provoke discussion and thought on our place in the universe. ( as it is already doing on this thread!!. I didn't catch the S.a.N. Program. What did they conclude on the Drake eqn? ~Pete

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    I agree with Pete that at the moment all solutions all possible. Obviously some solutions are more possible than others !!

    This quote from the website given below is one that I like: "The real value of the Drake Equation is not in the answer itself, but the questions that are prompted when attempting to come up with an answer. Obviously there is a tremendous amount of guess work involved when filling in the variables. As we learn more from astronomy, biology, and other sciences, we'll be able to better estimate the answers to the above questions".

    The site also has a Drake equation calculator so you can put in your own 'best guess'. The first term, N*, is currently the only one which can be given with any sort of accuracy - probably around 200 billion. http://activemind.com/Mysterious/Topics/SETI/drake_equation.html

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  • wassock by wassock moderator

    Heres the thing, all the stuff I have seen tends to assume that if life exists somewhere it will eventually achieve "intellegence". This seems to me non proven, the dinosaurs evolved over millions of years but we have no suggestion that so called intellegence (which seems to equate to 'can build a radio') was the end product. Thus I would suggest that intellegence is not an inherrent product of evolution, if it were then compared with our relatively stunted evolutionary tree the dinosaurs should have sent a dino Bruce Willis to blow up the asteroid that did for them.

    Second how much energy is needed to get to the stage where a powerful radio transmitter can be built? More to the point could we have got there, and thence to here, if we only had trees to burn (no oil/coal/gas)?

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  • p.titchin by p.titchin in response to wassock's comment.

    I think the Drake equation is a bit of a mischievous joke. N is supposed to be the number of developed life forms that we 'could communicate with', and gives little realistic thought to how, what , where and for how long life may exist in a given environment. It also gives little thought to how much longer life may have to exist on earth before WE have the technology to make contact with a far distant advanced life form whose e.m. receptors may be working on a totally different wavelength range than ours> The darned thing does tend to provoke discussion though, don't it! 😃 ~Pete

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    The Drake equation relates more to the SETI program (search for ET Intelligence) rather than a SETL program (search for ET Life).

    I think it's generally accepted by those who believe in life elsewhere that most of it will be fairly simple, ie algae, plants, bugs, maybe animals, and therefore uncontactable unless we go visit their planet. The implication here is that even if life is widespread throughout our Galaxy, 'intelligent' life will be be much rarer. I agree with you that intelligence is probably not an inherrent product of evolution and this will add to the rarity of intelligent life elsewhere.

    However, if we want to move beyond a simple belief system concerning life elsewhere then we need to start somewhere and the Drake equation makes that start. As Pete says, it's a bit mischeivous but makes for a good discussion. 😉

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  • mschwamb by mschwamb scientist, translator in response to wassock's comment.

    Hi,

    Interesting discussion. You might find this an interesting read as well. Goes over some of the terms i the Drake Equation and takes about a revised Drake Equation proposed by astronomer Sara Seager.

    Cheers,

    ~Meg

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  • Kitharode by Kitharode moderator in response to mschwamb's comment.

    Thanks Meg. My mate DrTechnical was gonna post the same thing last night, but you just beat him to it. It's a very well written article and I'm very much in favour of calling it a parallel equation, rather than an upgraded Drake equation.

    I'm also pleased that it adds weight to my point about the Drake equation relating to a search for intelligence, rather than just life, which is what Seager is trying to do. On the down side though, I can't do my follow up post where I was gonna suggest that we had a go at making our own 'Drake alternative' equation. Ho hum ... 😦

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  • wassock by wassock moderator

    So the most important part of determining the number of planets with detectable biosigns is the fraction of planets with detectable biosigns? All seems a bit incestuous to me.

    In all this the factor which seems to me to be glaringly missing from both equations is consideration of plate techtonics. We have 2 planets which fall into the "could maybe support life" category. One ran out of steam on the techtonics/vulcanism front and now has no atmosphere to speak of and probably no life any more, the other didn't and thus you are reading this. Thus should active vulcanism be included into the mix as something required for sustsined live, be it as we know it or otherwise? My surmise is the vulcanism is actually important in "regassing" the atmosphere. Mars had surface water and volcanos long ago (concurrently?) And theres even evidence for what maybe some sort of techtonics. No active volcanos now and no atmosphere, or is that just 2+2=5?

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    Once again, you make an excellent observation. http://www.astrobio.net/news-exclusive/plate-tectonics-could-be-essential-for-life/

    Personally I'm not convinced. I don't see tectonics as a 'must have' to get life started and the more we learn about life the more we find how durable and adaptable it can be. The necessary cycling of energy and nutrients might well be acheived by the mix of species present in a non-tectonic environment.

    Or not ... 😉

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  • wassock by wassock moderator in response to Kitharode's comment.

    Kinda agree re need for tectonics for life. But if such is needed to maintain an atmosphere for any great length of time then it's needed to allow enough time to build a radio for Drake and if there's no atmosphere then we can't detect the biosigns for the other. So it ought to be a factor in both (assuming that it's important for maintaining an atmosphere)

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    Yes. For the Drake equation (evolution of radio builders) tectonics might well be vital, so you can put me down as a supporter of your idea for the inclusion of a term in Drake to allow for this.

    It's certainly true that without an atmosphere to begin with we can't detect any changes to said atmosphere, but I'm still not convinced that it needs tectonics to maintain it. Lifeforms may well maintain it for themselves, or given the timescales we have to work with, perhaps even create an atmosphere of their own. At a later date, new species might then create the biosigns Seager is looking for.

    In short I'm guessing, but I'll certainly try to find out more about this. Excellent discussion point. Have a gold star. 😉

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  • Kitharode by Kitharode moderator

    PS to the above: From "Formation of Terrestrial Planet Atmospheres". Linda Elkins-Tanton, Massachusetts Institute of Technology, USA.

    "Planets may obtain atmospheres from three primary sources: Capture of nebular gases, degassing during accretion, and degassing from subsequent tectonic activity. Compositions of primitive and differentiated meteorites provide a range of reasonable starting bulk materials for planetary formation and atmospheric degassing; virtually all meteorites carry at least traces of water, carbon, and sulfur, while some contain as much as 20% water. Material delivered early is likely to have been processed through a planetary melting event (a magma ocean), which are assumed to occur one or more times during the first tens of millions of years of planetary formation through accretionary impacts".

    Which suggests we can have a planet, with an atmosphere, with water, without tectonics. If life gets a foothold on such a planet then it may be able to sustain its ecosystem over long periods, as I've already suggested. Maybe not 'radio builders', but that's not a requirement for the Seager equation.

    Hours of fun ... ** 😃 **

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  • mschwamb by mschwamb scientist, translator

    Hiya,

    You might find this an interesting watch, it was a summary of a recent conference held at the Space Telescope Science Institute.

    You also might find these papers interesting:

    http://arxiv.org/abs/1301.6674

    http://arxiv.org/abs/1404.5292v2

    Cheers,

    ~Meg

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  • wassock by wassock moderator

    Found this http://science.nasa.gov/science-news/science-at-nasa/2008/21nov_plasmoids/

    Which proposes a mechanism for how the atmosphere on Mars gets lost. Seems to me that something similar ought to be happening to the Earth as well? Ok we've got more gravity, but we're also closer in so the wind is stronger?

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  • Kitharode by Kitharode moderator

    Wassock: My first thought is that the Earth's magnetic field is stronger than Mars and it's 'teardrop' (rather than umbrella) shape is more effective at keeping the solar wind at bay. This needs confirming or denying.

    Meg: Nice links, thanks for posting.

    Everybody: If you've followed Meg's links and don't know much about the wonderful Main Sequence on the H-R diagram, I've got a Word.doc lesson on Star Evolution that covers it. (GCSE level). Sadly I can't get my dropbox link to work here, but if you want it send me a pm with an email address and I'll post it to you. My thanks to Garry Mayes for permission to do this. http://www.planeteartheducation.co.uk/

    Late edit: This seems to confirm my first thoughts on magnetic fields. http://genesismission.jpl.nasa.gov/science/module4_solarmax/solarmax_planets.html

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  • wassock by wassock moderator in response to Kitharode's comment.

    Kith when you putba dropbox link up you have to edit it, change www to dl no idea why but it works

    I was reading my paper as showing that itsvam iteraction between magnetic field and solar wind that wss biting chunks of atmosphere of and thus would also happen, to some extent, on earth

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  • mschwamb by mschwamb scientist, translator in response to Kitharode's comment.

    Mars doesn't have an active dynamo in the core. The core is pretty much cold and dead, unlike the Earth's core. So there is no magnetic field on Mars unlike Earth. There is a remnant patching places that are magnetized rocks but those are more local. No global magnetic field is present. MAVEN a NASA mission that just arrived at Mars is going to try to study the atmosphere to help figure out how the atmosphere was lost and what it was like before.

    Cheers,

    ~Meg

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  • wassock by wassock moderator

    Adds up to pretty much the same thing wrt my case. Cold dead core equals no vulcamism equals no atmosphere equals no ongoing or detectable life

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  • Kitharode by Kitharode moderator

    Something else that may be relevant in protecting Earth's atmosphere are the Van Allen Belts. In short, if the solar wind can't get to the atmosphere then it can't strip it away.

    "Van Allen Radiation Belts, two zones encircling the earth in which there are relatively large numbers of high-energy (fast-moving) charged particles. The particles are mainly protons and electrons, which are trapped within the belts by the earth's magnetic field .... The Van Allen radiation belts are centered along the earth's magnetic equator in a region of the upper atmosphere called the magnetosphere, or exosphere. The inner and more intense belt extends from roughly 600 miles (1,000 km) to 3,700 miles (6,000 km) above the earth; the outer belt, from roughly 9,300 miles (15,000 km) to 15,500 miles (25,000 km) above the earth. Scientists believe most of the particles that form the belts come from the solar wind". http://science.howstuffworks.com/dictionary/astronomy-terms/van-allen-radiation-belts-info.htm

    A third belt, more diffuse and transient, has recently been discovered. http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-065_Van_Allen_Probes_Belts.html#.VCLdjBbLLCQ

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  • Kitharode by Kitharode moderator

    PS to previous post: Thanks wassock. The edit works for me so hopefully it'll work for others. Should I also make the dl change when posting images?

    Lesson on Stellar Evolution: https://dl.dropbox.com/s/iqqiaf0g9njbj39/Lesson 6 - Star Evolution.doc?dl=0

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  • wassock by wassock moderator in response to Kitharode's comment.

    Yes dl to insert images into posts as well.

    Wrt radiation belts, they are a product of magnetic field which needs a molten core which equals vulanism (sort of) which brings us back to let you volcanos go out abd you wont have an atmosphere for long

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    I take your point. I might even agree with you, given time. 😉

    But what about Saturn's moon, Titan? The only volcanoes there are 'cold', more oozing than explosive, but it has a thick atmospere. No chance of life on the surface, but maybe (like Mars) something lives at depth.

    Perhaps more to the point: Venus has virtually no magnetic field, lies closer to the Sun than Earth, and has a dense atmosphere ... ?

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  • wassock by wassock moderator

    Ah - good question, clearly there's more than one thing going on wrt atmosphere. But Venus is quite big and has gravity similar to earth I think (did I see somewhere about there being a protective ionosphere which doesn't need a magnetic field?) Titan is somewhat further out, and so has less solar wind, think the important thing is that there's something bring up stuff from the interior to the surface and Saturn has a fairly chunky magnetic field itself which could protect Titan to some extent?

    But Venus is a tricky one I'll grant.

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  • Kitharode by Kitharode moderator

    Yes, there is some sort of non-magnetic interaction with Venus' atmosphere and the solar wind. Can't remember what exactly, but I'm sure we'll find out. Ditti the Saturn-Titan interaction.

    For a lifeless planet I can see that your idea of stuff from the interior being brought to the surface might well be a must-have if the atmosphere is to be sustained over long periods or, as with Venus, some sort of interaction with its parent star. For a living planet however (and just for the hell of it) I'm gonna stick with my suggestion that the lifeforms themselves might well be enough to maintain their own atmosphere.

    Finally, if I'm to survive your discussions over long timescales then I definately need more coffee ... 😉

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  • Kitharode by Kitharode moderator

    Having topped up my coffee levels and had a bit of a google (with chips) I've discovered that the 'Venus problem' is really difficult. But one or two items of interest might be worth consideration.

    Venus is similar in size and density to Earth, therefore similar in mass and with similar gravity, but its atmosphere (mainly co2) is much heavier than Earth's (nitrogen/oxygen) so it can hold on to it better.

    There is an ionosphere and solar wind interaction that helps protect the atmosphere from being stripped away.

    Venus goes round the Sun in about 225 earth days, but rotates on its axis in about 243 days, therefore its day is a little longer than its year. If this has slowed the core of the planet, or stopped it completely, then no magnetic field like on Earth.

    Radioactive decay and convection seem to be important considerations.

    Most of the stuff I looked at was really heavy reading and a bit much for me, but this is an easy and interesting read: http://www.britannica.com/EBchecked/topic/625665/Venus/54191/Interior-structure-and-geologic-evolution

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  • wassock by wassock moderator

    Been trying to find some numbers to show something like this for a while then good ole Prof Brian Cox delivers the goods in a docu on I-Player and it must be true cos Brian said so.

    Seems that every day we use up fossil fuels equivalent to a years worth of all the earths plant derived energy. I did think that we were using more energy than the planet could provide but never though it would be that much out of whack.
    OK so here's the pitch - if there is no plate tectonics then there's no sinking basins and thus no oil, may be a bit of peat or low grade coal but not much (and I think I've seen it writ that we only have coal because there were no bacteria which could break down lignin way back when). So no fossil fuel and we are limited to the amount of 'wood' we can grow, once our technology reaches the stage where the energy needed to maintain that level of tech equals the amount of energy we can get from burning stuff further development gets markedly slowed down. I'm making an assumption technical advancement and industrial growth go hand in hand with a steady increase in energy required.

    So all we need now is a nice graph showing the level of energy use against the amount of energy which can be produced agriculturally and we can see in what year we would have reached equilibrium and thus the stage of technology we'd have got to by then. I'm assuming this would have been some way before the development of semi conductors so solar power is not in the equation. Thus if we run out of energy before we get to radio then no matter how clever we are we can't get noticed by anyone out in space.

    Even with tectonics this energy gap would have done for the dinosaurs in terms of communicating their intelligence (had they evolved any) because the fossil fuels wouldn't have been "cooked" while they were in power and would have been of no use to them.

    So my idea is that it doesn't matter how clever a species is if they don't have access to to enough power they can't develop technology to send radio signals (and if they do they'll end up cooking the planet and wiping themselves out in the process?)

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  • Mote by Mote

    Not sure if I'm interrupting or whipping this poor beast, but I would like to hear your thoughts on the whole carrot idea. I do not mean to sound as if I am disagreeing with ideas, for none are wrong, and I offer this idea- would not having enough drive one to find more? I'm relativity pusher... the bacteria in the petri dish start at one side of the spectrum, plenty of food, and progress to the other side, reaching equilibrium, then evolution through adaptation occurs while observing and approaching the limit of starvation (producing antibiotics which reduce the number of competitors, let's say ), then because evolution does not occur fast enough relative to the size of the petri dish and the rate of growth of the bacteria, it does not evolve intelligence, it cannot figure out how to get out of the petri dish, it starves, and the poor little colony is toast (or cheese perhaps). My point being is there is a need for incentive, relative to the rate of growth and relative to surface area or volume (which is access to energy). Any thing can evolve, whether it's the expansion of information, dna, life, business, or artificial intelligence- and it will evolve until it meets a limit it cannot surpass. Given that without an incentive , random chance evolves something slowly, and it's in observing a limit that provides the incentive to adapt rapidly. Having access to enough and not having enough are both required to need a radio (an organism evolving an organ that allows communication in radio waves can exist, even if by random chance, if there is an incentive to evolve). Relativity is a state of being, an observation from which behind is nothing and ahead is everything, while both are infinite, the observation is not, it is something which relates the incentive for each to move, adapt, and overcome. I observed Drake's equation recently, chance would have it I observed your 6 day old post also, creating an incentive in me to move my rambling thoughts from my pile to yours in order to both give you a pile to adapt to and potentially receive more, allowing the expansion of information to overcome the boundary of my feeble mind. The laws of nature, motion, thermodynamics, all relatively conserved. Intelligent life in the galaxy will meet eventually, even if we have create it! 😃 (just throwin' this out there, what if a planet produces a species that is able to block or absorb radio waves biologically and they are able leave the planet through sporation, is that planet intelligently communicating or just reproducing?)

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  • p.titchin by p.titchin

    Perhaps it has taken so long that any other communicating life is in the parts of space that have now expanded so far from us that any electomagnetic emmisions,(including light) from their system can no longer reach us at the speed of light, as space continues to expand at an accelerating speed. and they are beyond our "horizon" 😉 ~Pete

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  • Kitharode by Kitharode moderator

    Phew ... My brain hurts. 😛

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  • PaulMetcalfe by PaulMetcalfe

    Hi,

    I thought I would put my non-scientific two-penneth in here related to the Drake equation.

    My understanding is that this equation basically postulates the number of planets capable of supporting intelligent ‘Biological’ life. But suppose that the normal for intelligence is not to require a body and therefore has no real need for a planet. Perhaps we on Earth (and probably other worlds) are just evolving energy patterns that haven’t mastered the way to communicate, travel etc. in that state and therefore are unaware of a multitude of intelligence out there.

    Perhaps we were out there and are taking an adventure holiday from the boredom of being able to do anything on a whim.

    Okay, I have posted this as a bit of fun to get away from the scientific talk but I do believe it very possible that intelligence can exist without a ‘container’ or habitable world and we will be incapable of understanding it at the moment and probably will not find it with any equation.

    Before anyone gets all scientific on this, I do write science fiction as a hobby and I created a whole universe of such intelligence. It releases the brain from thinking about research and investigation and is fun and not taken too seriously. I think I will just drift off into the ether now.

    Have a good Christmas.

    Paul

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  • p.titchin by p.titchin in response to PaulMetcalfe's comment.

    Fantastic response Paul. As I tried to intimate earlier in this thread, I think this is the whole purpose of the 'Drake Equation' - to instigate light hearted discussion amongst those interested, some of whom can sometimes be so serious in their thoughts that a little humerous 'brainstorming ' is therapeutic, and at the same time --- it provokes the imagination. 😃
    P.s. Are you he of ;science fiction chronicles'? ~Pete

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  • Kitharode by Kitharode moderator

    I think that's the beauty of the 'Just Chatting' board. It's a great place for small talk, chit-chat, humour and imagination, with absolutely no need for serious science. All of which could be said about the Drake equation. 😉

    Having said that, I like the Drake equation. I think it's well thought out and is a brave attempt to estimate the inestimable (if there is such a word). I'm resisting the urge to challenge anyone to do better - and I've just failed. ** 😛 **

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  • PaulMetcalfe by PaulMetcalfe in response to p.titchin's comment.

    Hi Pete,

    To answer your question - No - I am just a boring old hobby writer (actually not that boring - quite good really). In the new year, I hope to spend a lot more time on the Zooniverse projects and open a website for my science fiction. Unfortunately, I can't do a lot of marking on Planet 4 because of a recurring problem with the marking tools but it might go away like it did once before.

    Paul

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  • DZM by DZM admin in response to Kitharode's comment.

    I think that's the beauty of the 'Just Chatting' board. It's a great place for small talk, chit-chat, humour and imagination, with absolutely no need for serious science.

    That is exactly the point! And in the future, we're hoping to move such chatter into a shared space with other Zooniverse projects, so stuff that isn't project-specific can be enjoyed by all zooites together, regardless of their project(s) of choice. 😃

    @PaulMetcalfe , please share that sci-fi website when you get it set up! I'd love to read a thing or two of your hobby writing.

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  • p.titchin by p.titchin in response to DZM's comment.

    thanks DZM, thats exactly what our 'chat' board is about! Take care though, it's addictive. 😃 Good to get the other projects relaxing enough to have some science fun though. Good luck with your efforts.. ~ Pete

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