Carl Sagan Explains the Drake Equation

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Күн бұрын

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The most famous American astronomer and astrophysicist Carl Sagan explains the Drake equation.
The Drake equation (rarely also called the Green Bank equation or the Sagan equation) is a famous result in the speculative fields of xenobiology, astrosociobiology and the search for extraterrestrial intelligence.
The Drake equation states that:
N = R* × fp × ne × fl × fi × fc × L, where:
N is the number of civilizations in our galaxy, with which we might hope to be able to communicate;
R* is the rate of star formation in our galaxy
fp is the fraction of those stars that have planets
ne is the average number of planets that can potentially support life per star that has planets
fl is the fraction of the above that actually go on to develop life at some point
fi is the fraction of the above that actually go on to develop intelligent life
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L is the length of time such civilizations release detectable signals into space.
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Пікірлер: 360

@RyDawg084 15 жыл бұрын

I like how he explained it with pen and paper much easier to follow for people like me.

@jotatsu 15 жыл бұрын

As i remember from my physics class, ligth its an electromagnetic wave and as you mention space its not a perfect vacuum, there are still some atoms specially of hydrogen. This factor becomes relevant when trying to looks at something far away in the order of light years and that every "punctual" source of light still obeys the 1/r´2 factor. That why even modern telescopes/ radiotelescopes sometimes need to point for longer periods to take photos of far away objects.

@hossrex 15 жыл бұрын

I love this stuff. Love it. I'm an agnostic who believes alien life exists, but very far away. Yet... this entire equation can be summed up by saying "guess times guess times guess times guess equals GUESS." It's a HUGE assumption that half of the planets CAPABLE of supporting life will generate it, and it's a *HUGE* assumption to think that one tenth of planets that generates simple amino acids will someday yield life with the capacity to potentially develop technology.

@upstart1776 14 жыл бұрын

2:36.."BILLion"....classic Sagan....we miss you , Doc.

@SufianAhmads 17 жыл бұрын

I miss Carl Sagan :( The guy is just awesome!

@LoogyHead 16 жыл бұрын

As Sagan himself said, These numbers for the most part are estimates, while taking our solar system and planet as the "average." unfortunately we have no other yardstick to measure with so this is as fair as we can get for now

@OneillSG7 16 жыл бұрын

Wow, Sagan did an excellent job of explaining the Drake equation in this video. Sure I read the equation on Wikipedia but this is much easer to grasp. Albeit the Wiki article goes more in-depth about some of the variables and possibilities. I feel the estimation of the time period beings inhabit the planet capable of radio astronomy, at 1/100 million is a bit small -- however 1/100 is a big generous. Maybe more like 1/1 million? This is so interesting to ponder; there are so many possiblities

@GraveHorizon 13 жыл бұрын

You blew my mind with this! Not the likelihood of other similarly intelligent forms of life (that's already a given), but the badass simplicity in the reasoning behind it. Scientific reasoning FTW!

@arashjan 15 жыл бұрын

He explains everything in a simple language .I wish if he was my Calculus professor

@blizzalx 15 жыл бұрын

this gives me the chills

@Elenkeon 16 жыл бұрын

It's very easy to program this equation on a graphing calculator. If you do read the guide on how to make programs, you'll see it's easy to do.

@sonykroket 15 жыл бұрын

Carl Sagan is a hero.

@jamctelex 15 жыл бұрын

i love how the fraction of time that a planet hosts a technical civilization is represented by a mushroom cloud.

@akatauge 15 жыл бұрын

id like to clarify somehting here - sagan said that given cosmic conditions the modelcules of life assemble on their own. this is true... he isnt saying on the other hand that nucleotides just form on their own.

@richtea615 16 жыл бұрын

If there's one question I want answering in my lifetime, it's this one. Are we alone in the universe or not? My instincts tell me that life, especially intelligent life, is an exceptionally rare occurance. Imagine how much would change if one of them contacted or visited us - it could be the best thing that ever happened.

@COMMOGSE 14 жыл бұрын

@Richiehurtsalot You are correct about the structures. The real problem is though that silicium likes to connect to oxygen. The result out of that is sand or quarz.. Not really two lifesupporting elements.

@jamesvhawk 16 жыл бұрын

I thought that what you meant, I wasnt being sour in any way. I appologizise if you took it that way. I agree with you whole heartedly. It is a great piece of work, this video of Carl Sagan. Cheers James

@smithistheownage 13 жыл бұрын

@jeepndesert and in these courses complex math concepts are fully taught and the theories are fully explained and the evidence is offered for such concepts as x/0= undefined and infinity(0)=0. These are things of which mathematicians have come to a consensus on after centuries of rigorous mathematic exploration. Not to say that I would accept the ideas without first coming to a full understanding myself, but this does seem to suggest which course of belief is more applicable to reality.

@Catmandude 13 жыл бұрын

@Strangerinasland There is a difference between a guess and an estimation. For example, my step father was a sailor and asked me how high I thought a bridge 2 miles away was. I asked him how high the mast of a typical sail boat is (similar to ours). I projected that distance into an imaginary perspective line and counted by an estimated 10 units (for speed purposes). I came within 10 feet of the actual hight. A guess is 'heads or tails'? - where you have no basis for an answer, just a gut feel

@JBlackrose 17 жыл бұрын

WOW Im so Stoned right now. And Dr Carl just blow my mind away!!!! RIP Dr Sagan

@acuaman42 14 жыл бұрын

The problem with Drake equation is that it only considers FOUR dimensions, the same dimensions we are living right now. According to String Theory, there are at least ELEVEN DIMENSIONS, so that ecuation has very limited application.

@AriMalatesta 16 жыл бұрын

He was just giving a round number for a standard solar system, taking our Solar system as an average model. By the time there was discussion about naming Titan a planetoid instead of a moon, based on the same reasons that have recently "downgraded" Pluto from planet to planetoid. Also there were the first hints of some other object orbiting beyond Pluto, and of some planet between Mercury and the Sun wich didn't survive. Taking all this into account, 10 is a good average round number.

@sukiesoya 16 жыл бұрын

Incredible..my bet is on the millions of current technical civilizations..if a planet like us can do it I think that many others will be like it too.

@LordSirpiko 15 жыл бұрын

i love how he went conservative/underestimates all these numbers and it still comes out to 100 million possiblities.

@RyDawg084 16 жыл бұрын

the universe is so big and the chances of someone stumbling upon our solar system would be almost impossible

@dondiemarte 12 жыл бұрын

@MrNotoriousNinja And yes these factors are mere "guesstimates". Carl never claimed it to be more than that. Remember, he did this tv show back in the 80s. These factors would be changed from what we know now (with the Hubble and all).

@ArtDekko 16 жыл бұрын

Given the fact that our minds cant comprehend simple questions like: When did time start, and what happened before that? or How can space just go on forever?, I think our minds, its tools and what we consider to be logic are all ill-equipped to make any reasonable estimate. Perhaps some life forms exist, but are completely incomprehensible. After saying that, his ideas are quite fun to consider, and beautifully presented. The guy is an artist.

@000Elysium000 16 жыл бұрын

He's an amazing teacher. :)

@Tamooj 15 жыл бұрын

There is a lot of very deep, technical debate about the terms of the Drake Equation (and variants thereof). We fill in blanks every month as they find new planets, deep space organics, water in other systems, etc. Most researchers agree N is likely large... even disagreements of several orders of magnitude yields interestingly large values for N. Intelligent counter-arguments can be found in books like "Rare Earth", etc.

@AuspexAO 11 жыл бұрын

Ha ha, thanks for the suggestion on the EC video :)

@AllanCaetano_SP 15 жыл бұрын

I don't know if Sagan ever addressed the Fermi paradox - which is basically to ask, about the second hypothesis, "so where are they?" - in the "Cosmos" TV series. He certainly didn't do it in the book. Might be that Carl was one of those that are put down by its forebodings? Myself, I see it just as an open invitation to go exploring.

@ThePostRockProject 14 жыл бұрын

that equasion has changed slightly at the time that this was filmed as he said humans had only been sophisticated enough to possibly communicate with "aliens" for 30 years. that number has probably doubled since then. if anyone knows when this was filmed please let me know :)

@ChillStreamsLive 11 жыл бұрын

5:42-6:00 "If we multiply all these factors together, we would find, a hundred billion times a tenth times a tenth, or one billion planets on which civilizations have arisen at least once." Clear enough for you?

@almussalix 15 жыл бұрын

In an eternal time scale, yes, but just because its expanding forever doesn't mean it isn't finite at any given point in time.

@mynameFAISALmyname 16 жыл бұрын

yeh he sounds totally like mr smith!!! and i agree - great teacher

@bombarderoazul 15 жыл бұрын

When this video was made we had not discovered any planets around any star yet. As of june 2009 we know of about 350 planets discovered so far. It is estimated that there are about 6 billion stars with planetary systems like our own, I believe the latest drake equation based on new information, calculated that there are several thousand civilisations on our milky way alone.

@Tylerpierre99 17 жыл бұрын

That's a very conforting equasion, to think perhaps millions of civilisations could be out there right now thinking: I wonder who is out there, maybe a few are aware, and we are the exception....time will tell if e live to see it. great video!!

@Marzano15 14 жыл бұрын

There are so many astronomical events (like 1 in a trillion or smaller) that had to happen for us humans to evolve (I could list dozens and I'm not even educated on the subject aside from various articles n videos that I've read/watched,) that some scientists believe that perhaps the Universe isn't meant to support life, but that we hit the universal jackpot of real estate as well time period. I think there are probably only a few civilizations as impressive as ours out there.

@briantdt 14 жыл бұрын

this made me happy

@Achillesinhistent 16 жыл бұрын

Whether the equation is mathematically useful or not is irrelevent. The equation is important for it's possible implications. "Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying." attributed to Arthur C. Clarke -Arthur C. Clarke

@Jahan917 15 жыл бұрын

I agree, every ancient civilization has, some sort of story or myth of "people coming down from the sky" they didn't make those stories for no reason, that had some meaning to them. Theres even paintings of disc objects and such.

@dondiemarte 12 жыл бұрын

@MrNotoriousNinja Multiplying by fractions is the same as dividing. a x 1/2 is the same as a/2,

@bluesborn 16 жыл бұрын

Again,it's the unimaginably enormous scale of the known visible universe that must be taken into account.Even a thousand advanced civilizations in the universe(if evenly dispersed)would exist,in all likelyhood, beyond our reach or ability to detect.

@philthy122 13 жыл бұрын

@ThePostRockProject The equation has not changed at all "Drake's Equation" is the same now as it was when first postulated. What has changed is our understanding of the values that can be put in to the equation; ie, number of starts in our solar system, the fact that there are extra-solar planets (over 700 to date), availability of water in our own solar system an therefore the likely hood of life. We are a long way from solving Drake's Equation, but it is a fixed equation.

@kdwormy 16 жыл бұрын

10 advanced civilizations per galaxy is a pretty huge number if you calculate how many there must be in the universe (hundreds of billions of galaxies). I suspect Sagan has overwhelmingly overestimated the probability of the initial formation of life, such that there is probably only a handfull of inhabited planets in each galaxy and something like one out of every few thousand galaxies with advanced intelligent life.

@MadOldMan 15 жыл бұрын

The current calculation of the drake equation is N~ 2.31

@Bookworm35753 11 жыл бұрын

Although I agree with the notion that a vast amount of planets in the Milky Way can contain life, I do not agree that half of the planets that exist have had life of some sort at some point. We have about 9-10 planets of our own and only know of Earth having life (and very likely Mars at some point in the history). That is 2/10 or 1/5.

@scifi75 12 жыл бұрын

It hasn't even been a hundred years since we discovered that other galaxies existed and that they are in movement. The stars that we looked are but a few. We could be in an area of the galaxy considered "rural" to others or we could be overlooked as uninteresting or as an undeveloped race still prone to aggression. We also base the development a sentient race along our own conceptions. It all sums up that we still have much work to do and we need to get out in the stars to find out.

@pmacgilli 15 жыл бұрын

So true. I can never decide if the problem is a lack of imagination, a lack of desire to use imagination or a surplus of fear. Either way it's amazing how even very intelligent people are willing to make the leap to deism and then theism with no more reason than it seems like the only possible answer. Cheers.

@GanJiko 16 жыл бұрын

correction to my previous statement andromeda is the closest galaxy to earth its .77mpc's (megaparsecs) away.

@Doomcharger 14 жыл бұрын

@JLPVIDEO Problem with that line of thought. to go faster than you are currently going you need double the energy. so to travel at FTL speeds you need infinite energy.

@hossrex 15 жыл бұрын

No. He does. Right at *around* six minutes into the video. He makes a statement about how its legitimately possible that we'll "destroy ourselves tomorrow", and plots a variable in his equation at one hundred millionth, which gives the total sum of the equation at 10 civilizations in our galaxy. He then recalculates his equation making the assumption that civilizations might last long enough to be rated on galactic time scales, which recalculates to "millions" of civilizations.

@abarbar06 15 жыл бұрын

this little equation is only based on the stars of this one galaxy when in reality there are billions of galaxies out there

@LoogyHead 16 жыл бұрын

Then you must have been misreading it. From nasa's website (first search result for Jupiter): "The force of gravity at the surface of Jupiter is up to 2.4 times stronger than on Earth. Thus, an object that weighs 100 pounds on Earth would weigh as much as 240 pounds on Jupiter."

@savedfaves 11 жыл бұрын

I never knew how much of an estimate the Drake equation was. That 400 billion star number is big, though. And it seems the more time marches on the more likely it looks that all stars have 1 to several planets around them. So that 10 civilisations may be much higher.

@fntime 15 жыл бұрын

Mac,I can appreciate your comment. But where I disagree,'physical systems will follow a path of least resistance' I'm not sure that they 'physical system' you are talking about, is a 'galactic system' or a 'universe system' Until I see roses, on another planet,I'm going to presume they might be unique to the earth. I understand your point,Darwin felt that the system was DNA, and has nothing to do with anything other than a 'system. I need more,it's consistent with my experiences.

@bluesborn 16 жыл бұрын

I find the idea of being alone in a universe very unlikely,although given the scale of things the chances of ever communicating with other beings seems vanishingly small.

@fntime 15 жыл бұрын

I don't know Mac, if I agree with that. But thanks, for your intelligent response, I think, I'm going to 'meditate' on it! Thanks again, even if we don't agree, there is no necessity for rudeness, or anger.

@showmeanedge 14 жыл бұрын

@PMAJannetta Which both ways was I trying to have it? I only tried to make one point, which is that any extraterrestrial civilization en-route to here would need to be so sophisticated that they would be creating some of the needed resources for the trip, during the trip. It would be pretty hard to leave from another part of the galaxy and bring everything with you.The assertion that they need a habitable world is really just an assumption on your part.

@Peter7Paul 16 жыл бұрын

Great video and interesting equation. Although I do feel that he was a bit liberal with the estimates at times.

@COMMOGSE 14 жыл бұрын

@Richiehurtsalot That is only partly correct. Carbon is capable 4 million organic compounds, silicon only reaches about one hundred thousand anorganic compounds. Silicon is only capable of long chained molecules at the low temperature of -200c . Which prohibits life in itself as we know. At -200c chemical processes have also slowed down massively. And last but not least , silicon likes to react with oxygen and i think you know what that means.

@vampsith 14 жыл бұрын

We have to stop being so arrogant as a species to think that intelligent life is ANYTHING like ours here on earth. Also, Carl Sagan is the MAN.

@Adro1337 13 жыл бұрын

And lets not forget, the milkyway Galaxy is relatively small compared to several other recognized galaxies !!!

@ant16to 17 жыл бұрын

StreetcornerCatholic productins presents: "If I can't explain it, it's impossible"

@biunyia 16 жыл бұрын

back when dr sagan spoke these words in 81 82, since then the hubble telescope has found over 100 BILLION galaxieds and counting multtyply his calculations by 100 billion,,,,,the mind boggles

@franksaninocencio 15 жыл бұрын

with all of the current events of today, we should acknowledge the possibility that our planet has the potential of becoming one of those planets that don't survive.

@smithistheownage 13 жыл бұрын

@jeepndesert if it was infinity, then it would be defined as infinity in mathematics. Mathematicians have no problem grasping concepts of infinity. Imagine division by zero this way: Division by any number implies that that number goes into the numerator some 'x' amount of times. If we begin this operation with zero we see that by adding one zero to another we've gotten no closer to our numerator. So we continue to add zeros, but find it makes no difference. So, even after adding

@ChillStreamsLive 11 жыл бұрын

I don't know of what he contributed to Physics. I never heard of this dude in any Physics textbooks I've ever read. People like Issac Newton, Albert Einstein, Galieo, Niels Bohr, and Erwin Schrodinger contributed greatly to physics with theories like general relativity, classical mechanics and quantum mechanics. Carl Sagan, on the other hand, I've never even heard of until a few years ago.

@andyx1205 15 жыл бұрын

note that he got the number "10" for our GAlAXY alone, and there are more than 100 BILLION GALAXIES in the observable universe! so you add the # of galaxies in the equation and you get 10 x 100 billion, a trillion intelligent civilizations capable of communicating. note however many of them live billions of light years away, and we've only sent out signlas 200 years ago and have been accepting signals for only under 100 years

@Keitaro2011 13 жыл бұрын

By my calculations, if there are 10,000 civilizations evenly diffused throughout the galaxy, then the nearest one is 500 lightyears away.

@jaxxrr 15 жыл бұрын

AWESOME VID

@arryhuk 15 жыл бұрын

Amazing stuff

@marxmith 16 жыл бұрын

I understand. Thank you.

@r4v3nh34rt 14 жыл бұрын

Advanced or not, if they evolved on a planet similar to our own, then it surely won't lack of resources. We need them.

@KeithPhillips 16 жыл бұрын

400 billion within our OWN galaxy. There are a LOT more. Possibly even billions of billions, or far more than that. The Hubble Ultra Deep Field image which is about a 1 million second exposure of a very dark area in the constellation of Fornax, shows over 10,000 galaxies alone. Those galaxies would contain 100s of billions of stars just in and of themself. If even a billionth of each of those stars had intelligent life, the overall amount would still probably be billions of civilizations...

@dinosauravenger1989 16 жыл бұрын

No, he meant Jupiter and it's systems. Sagan believed that because of the desnsity of Jupiter's atmosphere may produce organic molecules, those life forms would be clouds of gas. Possible, but extremely unlikely for many reasons. IF there was life on Jupiter, it would be very simple, and not intellegent, more like a plant or something.

@ultravidz 16 жыл бұрын

the Drake Equation is still widely accepted, even today. he was just basing his explanations on the knowledge of the solar system available at that time...

@macwelsh007 15 жыл бұрын

Isnt that just calculating how many planets contain advanced civilizations over the course of the existence of the universe? What are the chances of those civilizations existing at the same time?

@Pr0xYk1ll4r 14 жыл бұрын

@acuaman42 Of course the equation is for our third dimension, its about the posibility of life in this universe, i dont doubt that there is life in other dimensions but we cant proove that, but we can proove life in this universe by looking at ourselves.

@MartinBarreby 16 жыл бұрын

no, but probebly they have discovered the radio signals since they are everywhere in the space. So that would be the best way to try to comunicate with others, and then use the internatinal language of the universe: math.

@JonasAlbrecht 15 жыл бұрын

Keep your faith, I'm sure it does you a tremendous good. Just don't stop the rest of us from exploring truths and possibilities.

@jannonball 16 жыл бұрын

Even if there is civilizations out there, how do we know they even want to communicate?

@cristianorem 16 жыл бұрын

thank you for your brilliant insight, do you have anything to back up your claims?

@termyextremo 16 жыл бұрын

I considear this video a very interesting and educative one.

@krophoto 15 жыл бұрын

no. you should listen again--he addresses that.

@harry_l_meredith 15 жыл бұрын

but everything needs to be so balanced- it just doesn't make sense for the number to be so high.

@hossrex 15 жыл бұрын

That actually is part of his equation, actually. Watch till the end.

@Letranger 16 жыл бұрын

I wonder how many people who think the LHC will cause some kind of cataclysm actually know anything whatsoever about what the LHC will actually do. If I were to guess, I'd have to say none of them, because anyone who knows what the LHC will do knows that it's perfectly harmless.

@phatmike21 14 жыл бұрын

I really hope our species gets its act together. As Sagan says, we have only lasted technologically around lets say 100 years and look at how much damage we have brought to the Earth. That is a fraction of a second in the Universal clock - there is a hump we have to get over to last hundreds of thousands of years, lets just hope we make it to that hump so we can truly explore the galaxy.

@blake119538 14 жыл бұрын

Why would nobody give him a transplant, nobody stopped to think that they were going to be dumbed down after Carl's passing.

@spase667 15 жыл бұрын

I loved this video.

@aetherflow 13 жыл бұрын

where is the variable for civilizations that do not want to be found ?

@2CSST2 14 жыл бұрын

@phatmike21 Indeed I think if Im not mistaken the fastest speed ever reached was about one ten thousanth of the speed light. For a time dilatation strong enough and thus making it possible to travel afar in the space we need to get very close to the speed light. It's already a challenge to make elementary particles atain such speeds... But another way would be to try to create a warm hole and a way to travel in it safely, if it is at least possible for one to exist...

@D0YA 15 жыл бұрын

I hope so bro, i hope so....

@veronicachic 13 жыл бұрын

TEACH ME MORE!!!!!!!!!

@XXIstCenturyBoy 14 жыл бұрын

No, we wouldn't attack. Years of hearing about the "Prime Directive" mean that we won't, just like years of hearing about the 3 laws of Robotics actually means that robotic theoreticist are trying to implement what was a romantized set of rules into real world robots. We like to think of the human race as savage, but we usually all root for the underdogs.

@NightSurfer47 16 жыл бұрын

The sad thing is we will most likely never make contact.

@1RadicalOne 15 жыл бұрын

I would have used 5% and 33.3% for the intelligent life and tech life parameters - most intelligent life will develop technology at some point.

@LoogyHead 16 жыл бұрын

The diameter of Jupiter is 9275 km greater at its equator than from its poles. Using newtons laws and the numbers given on Wiki, My own calculations give 28.33G's. All this means in context is if life COULD exist on Jupiter, it would be found nearer the equator. Feel free to correct me. I just used the law of universal gravitation. It's still much less than the 300G's you brought up.