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Horizon 2017: Strange Signals from Outer Space



 
 
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  #71  
Old July 15th 17, 04:06 PM posted to uk.tech.digital-tv
Robin[_8_]
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Posts: 451
Default Horizon 2017: Strange Signals from Outer Space

On 15/07/2017 15:03, Johnny B Good wrote:

Don't forget, as some proponents for the idea that life pervades the
whole universe would prefer you to believe, anyone is quite free to plug
their own values (best guesses) into this equation to obtain their own
guestimate. :-)


Most people treat the Drake equation as time-invariant. They take no
account of the evidence that mass-extinction events - even galactic mass
extinction events - were more frequent in the past. So the answer to
Fermi's Question may be "just hang about a bit longer".




--
Robin
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  #72  
Old July 15th 17, 04:51 PM posted to uk.tech.digital-tv
Johnny B Good[_2_]
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Default Horizon 2017: Strange Signals from Outer Space

On Sat, 15 Jul 2017 10:55:49 +0100, Norman Wells wrote:

On 15/07/2017 10:42, Roderick Stewart wrote:
On Sat, 15 Jul 2017 00:09:11 GMT, Johnny B Good
wrote:

The more I've learned about the series of very *fortunate* accidents
that lead to the Earth's environment that so swiftly became benign to
the evolution of life, the more I think that Drake's famous equation
represents an outrageous level of optimism in discovering other
intelligent species in the Universe that we can actually interact
with.


I've always thought exactly the same. The Drake "equation" is just a
string of estimated probabilities multiplied together. Some of those
estimates appear to be reasonable ones, based on facts, and since the
equation was first proposed we've discovered a few more facts - but not
(yet?) the most important one. We can make guesses at how life might
progress, but it's meaningless as long as we know nothing about the
probability of life appearing *at all*. Multiply several numbers
together, and no matter what they represent, if just one of them is an
unknown quantity then the whole thing is unknown. It looks like
mathematics, which makes it look clever, but really it's still just
wishful thinking.


It's not 'wishful thinking' but a best estimate based, as everyone
involved accepts, on certain informed guesswork. You're free to make
any other different assumptions you want and come up with a different
answer.


Quite true but, understandably, the SETI proponents will concentrate on
their own best guesses and play down the ones where the result tends
towards unity (i.e. Just Us!).


But your assumptions would have to be pretty wild to come to the
conclusion that intelligent life on earth is unique. They'd have to
exclude the possibility that the chemical processes leading to life here
could not or would not happen anywhere else at all. And I wonder if you
could possibly justify that.


Putting aside the question of *intelligent life* capable of producing
radio signals, from the evidence so far I doubt any scientist would
harbour such an extreme view as that. Indeed, our current understanding
of biochemistry suggests that whatever life forms which may arise
elsewhere outside of the Solar system, it's extremely unlikely that
they'd all be based on anything other than Carbon.

Limiting our scope to just that of Carbon based biochemistry might seem
a rather parochial attitude to the question of 'Life elsewhere in the
Universe' but, quite frankly, even with all of Carbon based compounds'
advantage of 'unstable complexes' throughout the liquid phase of water,
we're struggling to fathom out how in Ghod's name such precursor
complexity required to construct cellular life was able to arise in the
first place let alone how such cells managed to spring into being at all.
It seems a pretty safe bet that if life is to arise anywhere else in the
Universe, it will inevitably be Carbon based.

Although it may become possible to theorise about life based on a
different key element to Carbon, I suspect such a possible alternate life
form would probably require several lifetimes of the stellariferous phase
of the Universe in which to allow such an accumulator bet to pay off,
instead of the mere 10 billion years or so that it took for Carbon based
life to collect on its own accumulator bet.

When Einstein expressed his dislike of the new fangled quantum mechanics
theory by claiming "God does not play Dice!", I reckon he had the whole
concept of an omnipotent deity, responsible for everything in the
universe (including the Universe itself), totally arse about face. :-)

--
Johnny B Good
  #73  
Old July 15th 17, 05:55 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Default Horizon 2017: Strange Signals from Outer Space

On Sat, 15 Jul 2017 12:47:04 +0100, Jim Lesurf
wrote:

The more I've learned about the series of very *fortunate* accidents
that lead to the Earth's environment that so swiftly became benign to
the evolution of life, the more I think that Drake's famous equation
represents an outrageous level of optimism in discovering other
intelligent species in the Universe that we can actually interact with.


I've always thought exactly the same. The Drake "equation" is just a
string of estimated probabilities multiplied together. Some of those
estimates appear to be reasonable ones, based on facts, and since the
equation was first proposed we've discovered a few more facts - but not
(yet?) the most important one. We can make guesses at how life might
progress, but it's meaningless as long as we know nothing about the
probability of life appearing *at all*. Multiply several numbers
together, and no matter what they represent, if just one of them is an
unknown quantity then the whole thing is unknown. It looks like
mathematics, which makes it look clever, but really it's still just
wishful thinking.


Yes and no. :-)

We should distinguish between the *equation* which includes a series of
variables and the question of how we might decide actual values for each
variable in order to get an overall figures.


True, but for this equation we don't have an actual value for the most
important variable - the probability of life appearing spontaneously
independently of the life that we are aware of here on Earth, or the
number of times this has happened, whichever way you want to express
it. Without this value, the rest of the equation is useless as a means
of estimating the probability of life appearing elsewhere.

Its virtue as an equation is that it lets us divide the question into a
series of sub-questions about the value of each variable.


We can amuse ourselves as much as we want considering as many
sub-questions as we can think of, but without the answer to the most
important one - see above - we know nothing.

We can then look for ways to get plausible values for each variable as a
way to build a way towards the result the equation would then give.


Good. Let's do that. Let's try to find life that has arisen elsewhere
and thus provide a value for the missing variable, but in the meantime
let's recognise that we haven't found it yet. If anybody, even a
respected scientist (and they really ought to know better) says they
are "hopeful" of discovering extraterrestrial life, then that's all it
is - hope - not science, and certainly not an indication of the
probability of it happening.

We won't be able to calculate the probability of discovering
extraterrestrial life until we've actually discovered some
extraterrestrial life, and then we won't need to calculate it because
then we'll know. This would appear to render the Drake equation
pointless, but that's life. At least it's life as we know it.

Rod.
  #74  
Old July 15th 17, 06:04 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Default Horizon 2017: Strange Signals from Outer Space

On Sat, 15 Jul 2017 14:03:16 GMT, Johnny B Good
wrote:

It's true enough that most of the variables are just 'best guesses',
some of which may or may not be relevant (such as the need for a planet
in 'the Goldilocks zone' to suffer a collision with a Mars sized planet
in order to get a spin axis stabilising moon which will also provide
tidal forces to create interesting habitats to help drive evolution) but
this list of possible factors, if nothing else, provides targets for
research which may prove essential to determining whether or not there is
life elsewhere in the universe. The equation is part of the process in
gaining a better understanding of the problem.


Indeed. It gives us a better understanding of just how many variables
there could be, and to wonder how many of them might or might not be
relevant. That's an interesting set of concepts to wonder about in its
own right. For those of us who understand that that's all it is, there
isn't a problem, but unfortunately the Drake equation is often put
forward as a way of estimating the actual probability of finding
extraterrestrial life, and it cannot possibly be this until we have
credible values for *all* of its variables. As things stand at the
moment, one absolutely vital value is missing.

Rod.
  #75  
Old July 15th 17, 06:54 PM posted to uk.tech.digital-tv
Indy Jess John
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Posts: 1,218
Default Horizon 2017: Strange Signals from Outer Space

On 15/07/2017 17:55, Roderick Stewart wrote:

Good. Let's do that. Let's try to find life that has arisen elsewhere
and thus provide a value for the missing variable, but in the meantime
let's recognise that we haven't found it yet.


They have found "organic matter" in some meteorites, but nobody has yet
put their head above the parapet and said it demonstrates life rather
than a chance combination of chemicals.

So there is a reasonable assumption that organic chemistry exists
somewhere other than Earth, but it is perhaps a step too far to assume
that such an occurrence is an example of life elsewhere.

Jim
  #76  
Old July 15th 17, 06:54 PM posted to uk.tech.digital-tv
Robin[_8_]
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Posts: 451
Default Horizon 2017: Strange Signals from Outer Space

On 15/07/2017 17:55, Roderick Stewart wrote:
snip
We should distinguish between the *equation* which includes a series of
variables and the question of how we might decide actual values for each
variable in order to get an overall figures.


True, but for this equation we don't have an actual value for the most
important variable - the probability of life appearing spontaneously
independently of the life that we are aware of here on Earth, or the
number of times this has happened, whichever way you want to express
it. Without this value, the rest of the equation is useless as a means
of estimating the probability of life appearing elsewhere.


I do not know what you mean by "the most important variable". If you
mean "the smallest one" then it is just your assumption that that is the
probability of life arising. It might for all we know be the length of
time that communicative civilizations release detectable signals.

Its virtue as an equation is that it lets us divide the question into a
series of sub-questions about the value of each variable.


We can amuse ourselves as much as we want considering as many
sub-questions as we can think of, but without the answer to the most
important one - see above - we know nothing.

We can then look for ways to get plausible values for each variable as a
way to build a way towards the result the equation would then give.


Good. Let's do that. Let's try to find life that has arisen elsewhere
and thus provide a value for the missing variable, but in the meantime
let's recognise that we haven't found it yet. If anybody, even a
respected scientist (and they really ought to know better) says they
are "hopeful" of discovering extraterrestrial life, then that's all it
is - hope - not science, and certainly not an indication of the
probability of it happening.

We won't be able to calculate the probability of discovering
extraterrestrial life until we've actually discovered some
extraterrestrial life, and then we won't need to calculate it because
then we'll know. This would appear to render the Drake equation
pointless, but that's life. At least it's life as we know it.

Pedantic but important (well I would say that, wouldn't I?) point: the
Drake Equation (at least in its original form) does not deal with the
probability of *discovering* life, only the existence of active,
communicative extraterrestrial civilizations. Discovery depends on
other factors - eg how long do we listen? how hard? how?


--
Robin
reply-to address is (intended to be) valid
  #77  
Old July 15th 17, 09:43 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 1,974
Default Horizon 2017: Strange Signals from Outer Space

If it wasn't for the strange fact that electromagnetic waves will
propagate though a vacuum we would have no idea that the universe
existed other than the Earth. But since life would never have started on
Earth it wouldn't matter much.

Bill
  #78  
Old July 16th 17, 08:48 AM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,150
Default Horizon 2017: Strange Signals from Outer Space

On Sat, 15 Jul 2017 18:54:21 +0100, Indy Jess John
wrote:

Good. Let's do that. Let's try to find life that has arisen elsewhere
and thus provide a value for the missing variable, but in the meantime
let's recognise that we haven't found it yet.


They have found "organic matter" in some meteorites, but nobody has yet
put their head above the parapet and said it demonstrates life rather
than a chance combination of chemicals.

So there is a reasonable assumption that organic chemistry exists
somewhere other than Earth, but it is perhaps a step too far to assume
that such an occurrence is an example of life elsewhere.

Jim


"Organic chemistry" just means big molecules with carbon atoms, so
yes, the discovery of the chemicals alone is no guarantee that they
ever have or ever will develop into life. I remember the first lesson
of Organic Chemistry A Level, which began with the alkanes - methane,
ethane, butane, propane and so on. They all burn nicely but are a long
way from developing intelligence.

Rod.
  #79  
Old July 16th 17, 08:56 AM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,150
Default Horizon 2017: Strange Signals from Outer Space

On Sat, 15 Jul 2017 18:54:25 +0100, Robin wrote:

We should distinguish between the *equation* which includes a series of
variables and the question of how we might decide actual values for each
variable in order to get an overall figures.


True, but for this equation we don't have an actual value for the most
important variable - the probability of life appearing spontaneously
independently of the life that we are aware of here on Earth, or the
number of times this has happened, whichever way you want to express
it. Without this value, the rest of the equation is useless as a means
of estimating the probability of life appearing elsewhere.


I do not know what you mean by "the most important variable". If you
mean "the smallest one" then it is just your assumption that that is the
probability of life arising. It might for all we know be the length of
time that communicative civilizations release detectable signals.


The variables in the Drake equation are to do with the probabilities
of life developing in particular ways, becoming intelligent, inventing
radio, etc - all except one. That one variable is the probability of
anything that can be called life appearing *at all*. This is what I
mean by the most important variable, because until we can give a
numerical value for it, the others are useless.

[...]
Pedantic but important (well I would say that, wouldn't I?) point: the
Drake Equation (at least in its original form) does not deal with the
probability of *discovering* life, only the existence of active,
communicative extraterrestrial civilizations. Discovery depends on
other factors - eg how long do we listen? how hard? how?


Discovery of anything depends crucially on whether it is there to be
discovered in the first place. Until we know that, all the rest is
speculation.

Rod.
  #80  
Old July 16th 17, 09:25 AM posted to uk.tech.digital-tv
Norman Wells[_6_]
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Posts: 948
Default Horizon 2017: Strange Signals from Outer Space

On 16/07/2017 08:56, Roderick Stewart wrote:

The variables in the Drake equation are to do with the probabilities
of life developing in particular ways, becoming intelligent, inventing
radio, etc - all except one. That one variable is the probability of
anything that can be called life appearing *at all*. This is what I
mean by the most important variable, because until we can give a
numerical value for it, the others are useless.


Well, it's certainly happened here, on the only planet we know that much
about. What you have to consider is really the probability of it *not*
having occurred anywhere else in all the incredible vastness of the
universe.

You may think you're special and unique, but you're still just a bunch
of chemicals made up of a very low number of elements that are abundant
everywhere and are perfectly capable of combining anywhere in the same
way as in you.

Even your DNA contains just five of those: carbon, hydrogen, oxygen,
nitrogen and phosphorus.
 




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