# Thoughts on the Drake Equation



## Mirannan (Feb 28, 2015)

Prompted by watching a BBC4 documentary on the subject. To cut a long story short, the number of civilisations in the Galaxy with which we may be able to communicate seems to be roughly 5L, where L is the number of years for which a civilisation is on the phone, so to speak.

It's also worth noting that if the number is really small it's because L is small, which means that we won't be doing any communicating except by a miracle, because said civilisation will be extinct in these terms by the time our message gets to it. (If L is say 100, then if it is more than 50 lightyears away one exchange is possible before it disappears.)

However, there is in my opinion a hidden assumption buried in such speculations. And that is the assumption that a civilisation of great age will be a viable partner in a conversation. To illustrate this point, consider the technological difference between Earth in the 1920s and today. (1920s is very roughly the era in which radio communication became common.) And also consider the acceleration of technological change; it's at least arguable that Earth of 2015 is more different from the Earth of (say) 1999 than 1999 was from the 1920s, and the rate of change continues to accelerate. (Insert obligatory Singularity reference should you so desire.)

Now consider the case where L is maybe 100,000 years. How easy or otherwise is it going to be to communicate with a civilisation which has undergone a thousand centuries of exponentially accelerating change? Will they want to talk to us?

Which means that the L implicit in the Drake equation may well have nothing to do with the average life of civilisations but rather with the time before they ascend beyond anything we can understand. To take an example from fiction, if the Culture wanted to hide from us would we have any chance at all of even knowing they exist?


----------



## Brian G Turner (Mar 1, 2015)

I do find the calculations people put forward for assessing other civilisations to be so riddled with assumptions that it's difficult to see how they can be taken seriously - as you point out.

One thing space has always done is surprise us. IMO that's best kept in mind before anyone tries to tell us what to expect out there.


----------



## Venusian Broon (Mar 1, 2015)

It's an interesting point Mirannan, and I do think it is an unwritten assumption that when a civilisation reaches a certain point 1) it stays there 'sort of' and 2) they are as interested as us in contacting others

However the Drake 'equation' is one my bugbears. As Brian says it's so full of untestable assumptions (once you get past the easy star and planet stuff that we can actually measure to some degree) that any answer is practically meaningless. 

In fact I think that's why I dislike it so much - people with little understanding of mathematics and science can get hoodwinked by any answer as gospel from 'experts', and totally miss the point that the Drake equation _should_ just be a handy way of describing the assumptions we think go into the formation of intelligent life and civilisation. (as you have done Mirannan) Maybe one day we will be able to get some of the really airy-fairy parameters nailed down, but I can't see it happening for a very long time (if at all.)

As John Von Neumann said: *With four parameters I can fit an elephant, and with five I can make him wiggle his trunk
*
I'm clearly a bit grumpy this morning, so I apologise if the above came across as a bit of a rant


----------



## mosaix (Mar 1, 2015)

All guesswork.

If there's one thing we've learnt from the exploration of space it's that when you get there it's never as you expected - or guessed.


----------



## Ray McCarthy (Mar 1, 2015)

The Drake equation has a huge failing.
1) Radio many only be used for local portable devices or for long range LW/MW/SW, neither of which has likely enough range for Bernard's star.
2) Deliberate radio telescope (= big dish) is very narrow beam. It's unlikely.
3) Detecting civilisation by pollution + oxygen via spectroscopic analysis is best method, we have only started doing that.
4) Without something FTL, any meaningful two way communication is impossible.

Also in recent years we have moved from thinking a small proportion of stars might have planets and a smaller proportion are in Goldilocks zone to thinking that maybe nearly all stars have planets and most may have planets in the Goldilocks zone.

We need a new equation and a fresh approach to SETI, not radio based (Laser is no better than Microwave Radio).

Step one is "detecting" civilisation. 
We have no real idea how to do step two unless they are on the Interstellar doorstep (Communication).


----------



## Mirannan (Mar 1, 2015)

At least one of the factors is close to being testable, IMHO. The one I mean is fl, the fraction of life-suitable planets that eventually develop life. The incidence of planets and the fraction of Goldilocks planets were completely unknown when this equation first appeared; now they are reasonably well known but fl isn't.

The way to test this? If life is found in the Sol system with different chemistry from ours it means life is easy to form and the estimate of this goes way up. (Life on Mars or Europa that shares our genetic code doesn't help, because it might have hitched a ride on a meteor.)

The incidence of intelligent life? Well, first of all this only counts if they are tool-users; some people think dolphins are sapient, but without help they are not going to be building radio transmitters - ever. Second, our presence has probably suppressed the evolution of tool-using sapience in other mammals. IMHO it's quite likely that if humans disappeared, some other might well take over; perhaps one of the other primates, or raccoons, both groups having high intelligence and manipulating appendages. Or even elephants, perhaps.

Work on the ability of various animals to learn the use of tools helps nail down the incidence of tool-using sapience.


----------



## Ray McCarthy (Mar 1, 2015)

Mirannan said:


> Life on Mars or Europa that shares our genetic code doesn't help, because it might have hitched a ride on a meteor.


I think life may be very similar everywhere as the chemistry and physics is universal. The "hitching a ride" is a theory with an agenda. It's a frankly nutty idea. So IMO, even if life found elsewhere has some similarity, it's more likely by "Occam principle" that it originated there and not hitched a ride.

Either the Galaxy will be teaming with life in any environment that supports it or very odd indeed is that's it's rare or only here.


----------



## Ray McCarthy (Mar 1, 2015)

Mirannan said:


> some people think dolphins are sapient, but without help they are not going to be building radio transmitters - ever. Second, our presence has probably suppressed the evolution of tool-using sapience in other mammals. IMHO it's quite likely that if humans disappeared, some other might well take over; perhaps one of the other primates, or raccoons, both groups having high intelligence and manipulating appendages.


Dolphins seem to like fun. There is little evidence that they are even as smart as a British Rook!

No-one know really why UK rooks only show much tool using ability in a lab, or why apes, chimps are so dumb really. There is obviously more to it than having hands or a big brain.

We don't really know why we do what we do.


----------



## BAYLOR (Mar 1, 2015)

So far  we've found planets but baed on what we do know about then (which is very little) none of which  seem like  candidates for civilizations  or even life for that matter.


----------



## Vertigo (Mar 1, 2015)

I agree with all who say the Drake equation is really nothing but guess work. Even the incidence of planets in the habitable zone (sorry I just hate the 'goldilocks' name) does not take into account all of the many other factors. For example the Moon. 

Our moon is quite exceptional in the solar system in it's relative size to the earth and by extension is likely to be exceptional throughout space. And it contributes massively to the stability of our axis of rotation which in turn contributes massively to the stability of our climate. Without that stability it is hard to imagine the development of life much higher than microbial. 

It is clearly not enough to be within the habitable zone; just look at Mars and Venus, we have yet to find any evidence of life on either. And even if we do it is again hardly likely to be or have been any higher than microbial.

There are a whole host of other factors without which life or certainly higher life would not have evolved here - tectonics, abundant water, magnetosphere, abundance of heavier elements (you won't find nearly as many of them in the younger outer reaches of the Galaxy), habitable zone in both the solar system _and_ the Galaxy... the list goes on. Many planets in the galaxy might have one or two of these but not all and the signs are that we needed all of them.

Also, was the genesis of the very first self duplicating 'cell' just a cosmic fluke? After all the indications are that it occurred just once since all DNA on earth is related. Think about that for minute; just once in 4.6 billion years. Sadly I think most of us are overly optimistic about finding other life. I truly wish I could be more optimistic!


----------



## BAYLOR (Mar 1, 2015)

Places to look for habitable words , any yellow stars like our sun , with gas giants, since they suck up a cometary and asteroid debris.

We're not likely to find anything around Blue stars  because they  burns too hot and too fast and end as a supernova .  Not long enough for any kind of life to evolve

Red Stars tend to be old and near the end of their life cycle,  so no life their either.


----------



## Ray McCarthy (Mar 1, 2015)

Star too small and planet tends to suffer  more from flares because it has to be closer, which are worse on smaller stars.
Star too big and even further away to be cool enough, the UV content is too high.

A star has to also be a main sequence type.

That could still be  10 Billion to 100 Billion stars just in our own Galaxy. The estimate of total stars keeps going up.



Vertigo said:


> indications are that it occurred just once since all DNA on earth is related


That's an assumption. If in fact if the life we have is the only way it works, then there is no reason to suppose all life came from one kind of life. There is actually no historic evidence for a single origin.


----------



## J-Sun (Mar 1, 2015)

I don't look at the equation as being intended to produce a "six civilizations" sort of number. I think it's most useful as a conceptual tool which isolates many factors, suggests a scope to the problem, and produces fruitful further thinking. Everybody who's saying "it's flawed, it sucks, it should say X or consider Y" could just as easily say, "It's brilliant because it made me think about the problem in a more specific way and I realize it could also say X and I now consider Y".

But, yeah, you ain't gonna get a reasonable number out of it and there are always more factors to consider.



mosaix said:


> If there's one thing we've learnt from the exploration of space it's that when you get there it's never as you expected - or guessed.



I was just thinking about this the other day regarding today's exoplanet hunt. We actually think we know what we're talking about with these exoplanets based on the thinnest shreds of multiply-derivative indications and our extrapolations. Think about what we thought we knew about our own system in 1955 and what that picture looked like in 1985 and how it's even changed to 2015 and think about how are chances of being accurate about other star systems are now. Interstellar probes and boots on the ground. In the meantime, it's just high-tech guessing. Which is good as long as the guessing encourages exploration but not when it doesn't, obviously.


----------



## BAYLOR (Mar 1, 2015)

Ray McCarthy said:


> Star too small and planet tends to suffer  more from flares because it has to be closer, which are worse on smaller stars.
> Star too big and even further away to be cool enough, the UV content is too high.
> 
> A star has to also be a main sequence type.
> ...




You might want also rule out Binary star systems,. Having twin suns even the same if they both yellow  would mean double the energy and radiation output and what would orbits be like. Worse if the companion star is white dwarf or a black hole .


----------



## BAYLOR (Mar 1, 2015)

J-Sun said:


> I don't look at the equation as being intended to produce a "six civilizations" sort of number. I think it's most useful as a conceptual tool which isolates many factors, suggests a scope to the problem, and produces fruitful further thinking. Everybody who's saying "it's flawed, it sucks, it should say X or consider Y" could just as easily say, "It's brilliant because it made me think about the problem in a more specific way and I realize it could also say X and I now consider Y".
> 
> But, yeah, you ain't gonna get a reasonable number out of it and there are always more factors to consider.
> 
> ...



Until we can come with ship that will go faster then light  or one thats multigenerational  were not likely going to be able to go to those places anytime soon.


----------



## Ray McCarthy (Mar 1, 2015)

J-Sun said:


> "It's brilliant because it made me think about the problem


Yes, that's the important bit.

So if there were 1,000 to 10,000 Tech Civilisations today how would we best detect them? Actual communication seems problematic even if we knew someone was on a planet 100 Light years away never mind 10,000 light years away. Galaxy is about 100,000 LY across. The central bit and the extreme fringes may have less life. Otherwise it could be fairly randomly distributed. We'd have to be very lucky or a huge number of Tech Civs for one to be within 200 LY.


----------



## BAYLOR (Mar 1, 2015)

Ray McCarthy said:


> Yes, that's the important bit.
> 
> So if there were 1,000 to 10,000 Tech Civilisations today how would we best detect them? Actual communication seems problematic even if we knew someone was on a planet 100 Light years away never mind 10,000 light years away. Galaxy is about 100,000 LY across. The central bit and the extreme fringes may have less life. Otherwise it could be fairly randomly distributed. We'd have to be very lucky or a huge number of Tech Civs for one to be within 200 LY.



What if said civilizations used about tachyon based communications? Tachyons do travel faster then light right? But can we detect such things with out current level of technology ?


----------



## Ray McCarthy (Mar 1, 2015)

BAYLOR said:


> tachyon based communications



Tell me how it works and I'll draw up the plans.

There is no evidence that tachyons actually exist, and some theory that says they either can't or are only detectable if you are moving faster than light!


> the hypothetical tachyon particles which give the device its name do not exist even theoretically in the standard model of particle physics,


see https://en.wikipedia.org/wiki/Tachyonic_antitelephone

Especially "Don't eat the shrimp!"

The important first step which would divert spending from Military (for USA) to NASA is proof that other Tech Civs actually exist.

If we we were spending and doing more with space, then we might figure out Ansibles and Jump Drive, if they are at all possible.


----------



## BAYLOR (Mar 1, 2015)

Ray McCarthy said:


> Tell me how it works and I'll draw up the plans.
> 
> There is no evidence that tachyons actually exist, and some theory that says they either can't or are only detectable if you are moving faster than light!
> 
> ...




Hm ,  To much science fiction my part here Ray .There are some rather sizable gaps in my scientific knowledge. Okay so no Tachyons.


----------



## Ray McCarthy (Mar 1, 2015)

We need to start taking steps. At least discovering someone else, even if we can't communicate would seriously motivate the politicians to spend the money on the next step.  Really now we are not doing much beyond commercial and military satellites. A tiny amount on Space exploration and research. India did a Mars Mission for $75M.
Look how much ONE nuke powered  sub or nuke powered Aircraft carrier costs?


----------



## BAYLOR (Mar 1, 2015)

Ray McCarthy said:


> We need to start taking steps. At least discovering someone else, even if we can't communicate would seriously motivate the politicians to spend the money on the next step.  Really now we are not doing much beyond commercial and military satellites. A tiny amount on Space exploration and research. India did a Mars Mission for $75M.
> Look how much ONE nuke powered  sub or nuke powered Aircraft carrier costs?



The obscene amount of money wasted  for weapon systems.  It's a travesty that we spend so much money on weapons.

Imagine what kinds of exploration would be possible if Nasa had access to the  kind of money that defense gets.  Who knows ,we might  have gotten a manned  mission to Mars 15 years ago. Maybe a whole lot more.


----------



## Mirannan (Mar 1, 2015)

BAYLOR said:


> You might want also rule out Binary star systems,. Having twin suns even the same if they both yellow  would mean double the energy and radiation output and what would orbits be like. Worse if the companion star is white dwarf or a black hole .



Well, in the case of a binary with one member a collapsed object some rather violent things have happened in its past. But binary systems in general are possibilities, providing that they are either extremely close (and thus have a shared Goldilocks zone) or at least as far apart as Saturn is from the Sun because reasonably stable orbits could exist around either. The Alpha Centauri system would be suitable; a similar system with the B star being in a less eccentric orbit would be even better.

Regarding Mars and Venus, I've heard an opinion that if the two planets were swapped in position Sol system would have three habitable planets. Mars, somewhat warmed up, would be habitable and Venus twice as far from the Sun probably would be as well - or at least it would have a chance.


----------



## BAYLOR (Mar 1, 2015)

Mirannan said:


> Well, in the case of a binary with one member a collapsed object some rather violent things have happened in its past. But binary systems in general are possibilities, providing that they are either extremely close (and thus have a shared Goldilocks zone) or at least as far apart as Saturn is from the Sun because reasonably stable orbits could exist around either. The Alpha Centauri system would be suitable; a similar system with the B star being in a less eccentric orbit would be even better.
> 
> Regarding Mars and Venus, I've heard an opinion that if the two planets were swapped in position Sol system would have three habitable planets. Mars, somewhat warmed up, would be habitable and Venus twice as far from the Sun probably would be as well - or at least it would have a chance.



Alpha Centauri  A Sun is a yellow sun like our only 20 percent larger,  Alpha Centuri B is  an orange star slightly smaller and slightly less radiant then our Sun .  Proxima Centauri is red dwarf .   That system might have possibilities for habitation.


Venus in Mars orbit ,  I could be wrong here but wouldn't it be Ice age conditions?  If so it  probably habitable at the equator regions . Venus would still need a large moon to steady its axis to have stable seasons. Mars in Venus orbit could be like Death Valley only much much hotter and  probably not might be habitable on the surface. I could definitely be wrong here as well.


----------



## Vertigo (Mar 2, 2015)

Ray McCarthy said:


> That's an assumption. If in fact if the life we have is the only way it works, then there is no reason to suppose all life came from one kind of life. There is actually no historic evidence for a single origin.


Less of an assumption than the opposite. As far as I know all life on Earth shares a significant part of it's DNA. We, for example, share around 7% of our DNA with bacteria. The chances of that happening with independent genesis is vanishingly small. As far as I am aware the accepted scientific view is currently that all living organisms have a single common ancestor.


----------



## Stephen Palmer (Mar 2, 2015)

That's true. A hilarious attempt was recently made to prove "Life 2.0" here on Earth, something to do with arsenic metabolic systems or owt... got laughed out of court.


----------



## Ray McCarthy (Mar 2, 2015)

Vertigo said:


> accepted scientific view is currently that all living organisms have a single common ancestor


But it's purely a consensus based on the assumption that any commonality of DNA means a single origin.  It's a circular argument not actually based on evidence. A supposition.

Till we can examine life elsewhere, we can't tell. There are no preserved records of early enough life, nor any method to prove or disprove the any commonality of DNA = common origin theory.

I'm not saying I believe all life here hasn't a common origin, but there is a difference between supposition and real evidence.


----------



## Mirannan (Mar 2, 2015)

Ray, you are saying more or less what I did. But to clarify:

If ET life in the Solar System turns out to have identical basic chemistry (DNA/RNA with the same nucleic acid bases, genetic code and amino acids in use) as ours then it means that either (a) that's the only way life can work or (b) all life in the Sol system comes from a common origin on one of the planets. There is no clear proof either way, although I don't see how biochemistry with opposite chirality from ours and no other differences couldn't work - for example.

If, however, ET life (in vaguely Earthlike places such as Mars or Europa's ocean) has different basic chemistry from ours then that certainly does prove something. And that something is that life is extremely easy to get started.

Incidentally, some interesting although very preliminary work has been done on the formation of cell membrane-like structures at Titan temperatures in non-polar solvents like liquid methane, with the basic chemicals being polar molecules such as acrylonitrile - which happens to be detectable in Titan's atmosphere so it obviously can form somehow under Titan conditions.

Which means a rather weak hint that life in conditions very unlike those of Earth might, just might, be possible. It is worth noting that doing chemistry with liquid methane is very difficult on Earth. Apart from the obvious difficulties with cryogenic chemistry, there is also a serious fire and/or explosion risk.


----------



## Ray McCarthy (Mar 2, 2015)

Mirannan said:


> very preliminary work has been done on the formation of cell membrane-like structures at Titan temperatures in non-polar solvents like liquid methane, with the basic chemicals being polar molecules such as acrylonitrile


Though the researchers are ONLY demonstrating a membrane and admit they are not biologist.

Interesting, but a long way from biology or life. Certainly Ammonia rather than water has been postulated. But as with this only a few isolated aspects have been demonstrated.

The chirality thing is very odd indeed. You'd expect the opposite shape but otherwise same formula organic chemicals to have the same properties. But some don't. Perhaps because everything, like Alice through the Looking glass needs reversed. An oddity too is that synthesised compounds (sugars?) often seem to be opposite handed. You can make a Kerr cell with a sugar solution and detect the chirality (handedness) with polarised light.

Do Clouds naturally polarise light in one aspect? A sunstone is a primitive polariser and I think helps to spot sun's location when sky overcast?
https://en.wikipedia.org/wiki/Sunstone_(medieval)

If clouded skies are ALWAYS a particular polarisation, then for photosynthesis there is advantage of same "handedness" (chirality). Then everything is going to have chirality to match the handedness of that first photosynth cell.  Otherwise enzymes etc don't work so well, sugar won't be as sweet etc...

Maybe all completely nonsense, just thinking about it as I type. It's odd.

Plants use Xanthophyll (not just Chlorophyll), apparently we have it in our eyes too

https://en.wikipedia.org/wiki/Xanthophyll


----------



## Mirannan (Mar 2, 2015)

Ray - I did look into the chirality thing and it appears that there are two ways of defining chirality for a particular molecule, one of which is more fundamental than the other. They are distinguished in the literature by using lower or upper case letters, I believe.

Essentially, just about all biological molecules are interconvertible. By some accident of stereochemistry, if one follows the long chain of reactions to make (say) glucose from an l-amino acid then that glucose is in the d form. For further explanations, it turns out Wikipedia explains it all quite well:

https://en.wikipedia.org/wiki/Chirality_(chemistry)


----------



## Ray McCarthy (Mar 2, 2015)

I did organic chemistry back in the Plasticine age. 
It's fascinating stuff.


----------



## Vertigo (Mar 3, 2015)

I accept what you say Ray, and I know you are not rejecting the single origin idea, but I think he argument is somewhat stronger than you suggest. It's not like it's just the chemistry that is the same it is the actual gene sequences that are the same and that is a level of complexity that it is hard to imagine being duplicated in any other way. But beyond that I'll bow out as my knowledge of organic chemistry goes no further than what I have learnt from documentaries etc 

But I'd still go back to my original point that the conditions that have produced higher life forms on Earth are far far more complex than just being in the habitable zone and having water. Which is why I tend to think the Drake equation overly optimistic. The single origin idea is really just one of those factors though if correct a pretty major one. But I can't see how we'll ever really know that one for certain.


----------



## Brian G Turner (Mar 3, 2015)

Vertigo said:


> the conditions that have produced higher life forms on Earth are far far more complex than just being in the habitable zone and having water.



Very much agree - it's limiting ourselves to the familiar, rather than possible.



Ray McCarthy said:


> Till we can examine life elsewhere, we can't tell. There are no preserved records of early enough life, nor any method to prove or disprove the any commonality of DNA = common origin theory.



There are a lot of scientists who agree that abiogenesis on earth is problematic - Fred Hoyle and Francis Crick both calculated that statistically it is improbable. There are further concerns about just how quickly life actually appeared for it to have been a random event, with the additional problem that all the ingredients required for life to develop might not have been available. The number of objections appears fairly significant.

Am currently reading about this very topic in "Evolution of life from space" by Chandra Wickramasinghe of Cardiff University - fascinating reading.


----------



## Stephen Palmer (Mar 3, 2015)

Brian Turner said:


> There are further concerns about just how quickly life actually appeared for it to have been a random event, with the additional problem that all the ingredients required for life to develop might not have been available. The number of objections appears fairly significant.



These to my mind are minor, or even irrelevant concerns. Even with people like Andrew Knoll around, we still don't know enough about the very early conditions to say anything with conviction. Imo, Fred and the rest have vivid imaginations. Just a personal opinion.


----------



## Nick B (Mar 3, 2015)

I think until we have some idea how frequently life evolves it is just to hard to make any sensible conclusions. If life happens easily, the chances of cvilizations arrising is good, if life is incredibly unlikely to evolve then intelligent life may be unbelievably rare no matter how many goldilocks planets there are.


----------



## Stephen Palmer (Mar 3, 2015)

True. One reason I want to live to see the results of the Europa expedition!


----------

