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Searching under the lamp-post - Comments

DefenderOfReason!'s Avatar Comment 1 by DefenderOfReason!

There just HAS to be other life-forms out there. The Cosmos is just too enormously vast. Even if the odds were 100 billion:1, life would still be abundant outside of Earth. We live in such exciting times, as far as scientific advances go, and I hope that in my lifetime humanity discovers we are not alone.

Mon, 26 Dec 2011 19:16:32 UTC | #902802

justinesaracen's Avatar Comment 2 by justinesaracen

Yes, that would be one of the most thrilling pieces of news I could imagine, that bacterial life has been discovered on another planet. That would represent a revelation that would equal Darwin's discovery/description of evolution and I would go to my grave pleased to have lived at that bright moment in human history. The implications are staggering.

It would also be interesting to see how the world's believers would integrate that piece of information into their theologies. Or perhaps they would just ignore it, as they do the god-destroying facts of evolution and cosmology.

Mon, 26 Dec 2011 19:34:24 UTC | #902808

huzonfurst's Avatar Comment 3 by huzonfurst

Science continues to advance exponentially, and if society can mature enough to keep from destroying the earth's ability to support life in the next few decades the progress promises to be astounding: nanotechnology to repair cells one molecule at a time leading to life extension and aging reversal, the perfection of genetic engineering, fusion power, teleportation, faster-then-light communication or travel, making daily backups of oneself in case of mishap to be downloaded into one's identical clone, who knows what might be discovered?

Mon, 26 Dec 2011 19:39:02 UTC | #902809

Alan Canon's Avatar Comment 4 by Alan Canon

I don't know the source, but there's a comment as I remember Sir Arthur Clarke once made on the subject of contact with E.T.s: "It may never happen...or it might be the only headline in tomorrow's newspaper."

Mon, 26 Dec 2011 20:10:02 UTC | #902816

Rich Wiltshir's Avatar Comment 5 by Rich Wiltshir

I hope Davies succeeds, but imagine the chances are quite low.

Lamposts or the light of fires?
Fire shares many qualities that may define life. It consumes and replicates but doesn't mutate. On this planet, the fire of life has occupied extremes of conditions and scale. Like fire, life spreads Is it reasonable to infer that Earth is just one ember within the solar system, one ignitition point for self replicating DNA? Life on Mars, Ganymede and Titan or the extremes of Ceres and Jupiter wouldn't surprise me. Multicelular life wouldn't surprise me. But a non-related self replicator would bowl me over.

And religion? Some form of fungal infection, surely?

Mon, 26 Dec 2011 20:34:26 UTC | #902820

HenkM's Avatar Comment 6 by HenkM

I am with those who say life is (extremely) rare. It s no use putting odds at its feet.

I do have a question though: .... " it was established those rocks came from Mars " .....

Rocks are, then, the same as fingerprints? Their (the rocks on Antarctica) make up can only be from Mars, and from Mars only. To me that sounds like circle reasoning.

All other planets about have been thoroughly examined in that way? And I mean: all other planets in the universe.

Mon, 26 Dec 2011 21:19:50 UTC | #902824

Steve Zara's Avatar Comment 7 by Steve Zara

When it comes to searching for ET, I have been influenced by the views of the author Stephen Baxter. If we have to search for ET, then ET almost certainly does not exist.

We can already think of ways to harvest the energy of our sun that would make us visible well across the galaxy - the change in spectrum that would result if we constructed even a partial Dyson Sphere to capture the Sun's energy would make our solar system look very odd indeed from a distance.

We can also come up with ways to send probes or even colonies of humans to other stars. All it would take is for one such colony to be launched every few thousand years from each star and the galaxy would soon look inhabited on cosmic time-scales.

We should not need to look under lamp-posts to find E.T.

However, if E.T. is found there, I would be overjoyed.

Mon, 26 Dec 2011 21:35:46 UTC | #902826

Quine's Avatar Comment 8 by Quine

The problem is that we have no way to know the size of the "it's life, but not as we know it" set. It may be that life has to be much like it is here to get started, but we don't know if that is true, and even if it is true we don't know where that can go with enough time. Especially unknowable are cases in which the extended phenotypes of living things loop back and change the rules. For example, there is nothing stopping us from using our technology to generate a new type of "life not as we know it" that simply could never have gotten started, in that form, by itself.

Mon, 26 Dec 2011 21:44:57 UTC | #902830

aquilacane's Avatar Comment 9 by aquilacane

It is highly unlikely that the same 64-triplet code would coincidentally evolve more than once independently,

Is it unlikely that the same elements from the periodic table should coincidentally occur more than once independently? Perhaps in the right conditions some things are inevitable. It may not be a coincidence but a necessity. Life may be the path of least resistance if DNA forms naturally with the right environment. What else would it form and why? Why behave differently? The variety of building blocks flying around the universe may be too small to provide for a wide variety of life. There may only be a few simple combinations that can get life going. Who knows?

Mon, 26 Dec 2011 21:57:20 UTC | #902834

Functional Atheist's Avatar Comment 10 by Functional Atheist

Apologies if this sounds smug, but I'm not convinced that finding fossil evidence of former microbial life on Mars would really be so earth-shaking to most humans.

The hard-core religious are unmoved by astonishing fossils on earth--modest fossils from Mars would be easy for them to ignore. The 'normal' public would yawn, as popular movies has built among them an expectation that alien life would be much more exciting than tiny fossils. Scientists and civilians of the sort who read this website would be excited, but not terribly surprised--in such an enormous cosmos, brimming with organic molecules, it would only amount to a partial confirmation of the more optimistic estimates regarding the prevalence of simple life.

A non-extinct population of Martian bacteria would have a deeper impact, but it still might not amount to more than a blip in the popular consciousness--the story of the year, perhaps, but shrugged off as no big deal within a few years.

Intelligent aliens are an entirely different matter, but then they are also much more improbable.

Mon, 26 Dec 2011 22:49:44 UTC | #902844

Alan4discussion's Avatar Comment 11 by Alan4discussion

Meteorite impacts have certainly thrown planetary matter into orbit and beyond, and there were many more impacts in the early history of the Solar System.

Some early ideas of interplanetary transits by matter from one planet to another have been discounted. Tektites are now thought to be Earth rock re-entering the atmosphere from space after meteorite impacts have exploded Earth ejecta into space.

Tektites Early nonterrestrial impact theories
Aerodynamically shaped Australite; the button shape caused by ablation of molten glass in the atmosphere.
Though the meteorite impact theory of tektite formation is widely accepted, minority theories propose alternate ideas of tektite formation.
Tektites contain no cosmogenic noble gases produced by cosmic rays, a factor that excludes long travel in space, necessary if tektites are not terrestrial. According to terrestrial-impact adherents, this makes a lunar origin unlikely, because it is hard to reconcile with finding cosmogenic noble gases in all lunar meteorites – a typical lunar meteorite taking about 1 million years to transfer from Moon to Earth.

Like meteorites identified as from Mars, some have been identified as Moon rocks:-

About 134 lunar meteorites have been discovered so far (as of October, 2010), perhaps representing more than 50 separate meteorite falls (i.e., many of the stones are "paired" fragments of the same meteoroid). The total mass is more than 46 kg. All lunar meteorites have been found in deserts; most have been found in Antarctica, northern Africa, and the Sultanate of Oman. None have yet been found in North America, South America, or Europe.[2]
Lunar origin is established by comparing the mineralogy, the chemical composition, and the isotopic composition between meteorites and samples from the Moon collected by Apollo missions.

@OP - Conversely, if f we found a life form with a very different genetic code – not DNA, or DNA with a different code – we would call it truly alien.

It would still be possible to have a different genetic code from within the Solar System if, for example, living material from the RNA World of early evolution was transferred to another planet by an impact, and then continued to evolve separately. It is possible this could have happened in either direction between Earth and Early Mars.

- A Martian meteorite is a rock that formed on the planet Mars, was ejected from Mars by the impact of an asteroid or comet, and landed on the Earth. Of over 53000 meteorites that have been found on Earth, 99 are Martian (as of 2011-07-30) These meteorites are thought to be from Mars because they have elemental and isotopic compositions that are similar to rocks and atmosphere gases analyzed by spacecraft on Mars.[2]

Mon, 26 Dec 2011 22:49:47 UTC | #902845

Premiseless's Avatar Comment 12 by Premiseless

If ever out late and stuck for the time, I used the method of standing beside a lamp post and reading the shadow. It always approximated to 'after dark'. It's the same method religious people use when referring to ancient writings. Always very late.

Mon, 26 Dec 2011 22:56:58 UTC | #902848

Rodger T's Avatar Comment 13 by Rodger T

I think the vatican "astronomer/astrologer" has already claimed any life found outside of planet as all part of their gods creation. Gotta keep the bases covered ,you know.

Mon, 26 Dec 2011 22:57:46 UTC | #902849

Acitta's Avatar Comment 14 by Acitta

Interesting that RD starts off this article with a story originally attributed to the Sufi Muslim Mullah Nasreddin:
Mullah Nasruddin The Story of Lost Key.

Mon, 26 Dec 2011 23:54:25 UTC | #902856

mmurray's Avatar Comment 15 by mmurray

Comment 1 by DefenderOfReason! :

There just HAS to be other life-forms out there. The Cosmos is just too enormously vast. Even if the odds were 100 billion:1, life would still be abundant outside of Earth. We live in such exciting times, as far as scientific advances go, and I hope that in my lifetime humanity discovers we are not alone.

The number of stars is about 10 to the power of 22. If the odds are life are N : 1 where N is bigger than 10 to the power of 22 then life is unlikely anywhere else . We have very little idea what N is.

Michael

Tue, 27 Dec 2011 00:03:44 UTC | #902857

mmurray's Avatar Comment 16 by mmurray

The analogy of meteorites in antarctica is not quite the same as the keys under the light story. Meteorites are uniformly spread across the surface of the earth so looking for them where you have a chance of finding them makes sense.

Michael

Tue, 27 Dec 2011 00:10:01 UTC | #902858

DefenderOfReason!'s Avatar Comment 17 by DefenderOfReason!

N = RfpneflfifcL

In this equation, N is the number of detectable civilizations in our galaxy. The other variables are described below:

•R is the rate of star formation in the galaxy
•fp is the fraction of stars that form planets
•ne is the number of planets hospitable to life (i.e., Earth-like planets)
•fl is the fraction of these planets on which life actually emerges
•fi is the fraction of these planets on which intelligent life arises
•fc is the fraction of these planets with intelligent beings capable of interstellar communication
•L is the length of time such a civilization remains detectable
The only variable known with any degree of certainty is the rate of stellar formation, R. In the Milky Way, a typical spiral galaxy, new stars form at a rate of roughly four per year. The variable astronomers feel most uncertain about is L, the length of time a civilization remains detectable. A variety of estimates have been used for L, ranging from 10 years to 10 million years.

Astronomers can make educated guesses about the rest of the variables. For example, of the nine planets in our solar system, only four are what astronomers call terrestrial planets -- those that have a solid surface. Of those terrestrial planets, only Earth supports life. If we take our solar system as representative, then we might argue that ne equals 1/4 or 0.25. Similar guesses have been made about the other variables and, interestingly, they all end up having very similar values, usually in a range between 0.1 and 1.0. So, a typical calculation might look like this:

N = 4 x 0.5 x 0.25 x 0.2 x 0.2 x 0.2 x 3,000,000

which gives us a value of 12,000 civilizations in our galaxy.

Drake's original calculations were very close to this value for N. When he ran the numbers, he predicted that there might be 10,000 detectable civilizations in the Milky Way. Carl Sagan, a leader in the SETI movement until he passed away in 1996, was even more generous when he suggested that 1 million civilizations might exist in the galaxy

And mind you, this is merely intelligent life which is detectable. I'd imagine the odds for some sort of microbes, living or extinct, would be much greater.

Tue, 27 Dec 2011 00:52:47 UTC | #902865

Tyler Durden's Avatar Comment 18 by Tyler Durden

Comment 17 by DefenderOfReason! :

For example, of the nine planets in our solar system

Sorry to be pedantic, but it's now eight planets due to Pluto's recent downgrade to dwarf planet (plutoid) by the International Astronomical Union (IAU).

Tue, 27 Dec 2011 01:20:47 UTC | #902869

smitemeifudare's Avatar Comment 19 by smitemeifudare

Given the size of the universe, i think it is an absolute impossibility that life has not evolved elsewhere in it

Tue, 27 Dec 2011 01:22:10 UTC | #902870

mmurray's Avatar Comment 20 by mmurray

Comment 17 by DefenderOfReason! :

N = RfpneflfifcL

We don't know hardly any of these numbers to any degree of accuracy. What reason for example do you have for assuming any particular value for fl and fi ?

Have you seen the Rare Earth hypothesis.

If you read the wiki entry on Drake's equation you will see the sort of guesswork involved. All Drake's equation is good for is telling us what we would need to know to estimate N and to thereby motivate further scientific work. For example the Kepler mission has told us some really interesting things about fp.

Michael

Tue, 27 Dec 2011 01:37:39 UTC | #902872

mmurray's Avatar Comment 21 by mmurray

Comment 19 by smitemeifudare :

Given the size of the universe, i think it is an absolute impossibility that life has not evolved elsewhere in it

Given the beauty of the stars there just has to be God right ?

Michael

Tue, 27 Dec 2011 01:38:10 UTC | #902873

Steve Zara's Avatar Comment 22 by Steve Zara

comment 21 by mmurray

Given the beauty of the stars there just has to be God right ?

Michael

I'm more sympathetic to the view that life is widespread. Doesn't it look increasingly like planets turn up just about everywhere, and the basic chemical ingredients of life are common? Also, as more and more research goes into the questions of the possible origin of life, it seems to be turning out to be not that hard at all, and perhaps even a normal occurrence on planets like the early Earth.

It's also interesting that water-splitting photosynthesis seemed to get started very quickly as well, so the oxygen-rich environment needed for active multi-cellular life was also likely, even though it took a long time for the chemistry of the seas to change sufficiently.

Perhaps complex animal life is extremely common on a cosmic scale. I think this is looking ever more likely, although another sample of a biosphere would help the statistics!

Tue, 27 Dec 2011 01:49:41 UTC | #902875

mmurray's Avatar Comment 23 by mmurray

I'm more sympathetic to the view that life is widespread. Doesn't it look increasingly like planets turn up just about everywhere, and the basic chemical ingredients of life are common? Also, as more and more research goes into the questions of the possible origin of life, it seems to be turning out to be not that hard at all, and perhaps even a normal occurrence on planets like the early Earth.

It's also interesting that water-splitting photosynthesis seemed to get started very quickly as well, so the oxygen-rich environment needed for active multi-cellular life was also likely, even though it took a long time for the chemistry of the seas to change sufficiently.

Perhaps complex animal life is extremely common on a cosmic scale. I think this is looking ever more likely, although another sample of a biosphere would help the statistics!

I'm also sympathetic to it just not the argument that the universe is really big so life must occur elsewhere. The expected number of stars with life on a planet around them is

(number of stars ) x ( probability of life occurring on a planet around a star )

we know the first number is big but very little about the second. The gut feeling that because the first number of really, really big the second one can't be so small as to make the product a lot less than one is what I object to. It isn't an argument. You have to do some research. Kepler and the research on abiogenesis is a lot more persuasive I agree. Genuinely different life on Mars or Europa would be outstanding.

Michael

Tue, 27 Dec 2011 01:58:30 UTC | #902878

Steve Zara's Avatar Comment 24 by Steve Zara

Comment 23 by mmurray

The gut feeling that because the first number of really, really big the second one can't be so small as to make the product a lot less than one is what I object to. It isn't an argument.

Isn't it sort of an argument, though? The idea that Earth is special is a bit too anti-Copernicus, isn't it?

So much of science is based on the idea that we are in a typical situation in the universe. It would be a bit odd if we were in the only solar system that had a very special sort of chemistry that was necessary for life.

I know this isn't much of an argument, but I think the Copernican principle does tend to point in the direction of life being reasonably common.

We'd only really know if we found life that was different, such as having different nucleotides. I suspect that there has been so much contamination of microbes between the planets of our solar system through asteroid impacts splashing out debris (bacteria can survive those sorts of forces with no problem) that I would expect us to find life on Mars somewhere, and it's going to be bacteria and/or archaea.

Tue, 27 Dec 2011 02:45:59 UTC | #902887

rjohn19's Avatar Comment 25 by rjohn19

I am going to disagree with a couple of posters here. I have found this to be a low-payout proposition for myself but I persist because I usually learn something in the process which is the main reason I spend so much time here.

First to Steve Zara (I’m in for a serious ass-whupping here)- If we have to look, it’s not there… If you meant by that it’s probably not under the lamp post, then I’d agree. But as radio waves travel the speed of light, our earliest signals have only crossed about a tenth of our own galaxy, which I don’t consider statistically relevant. Incoming signals would suffer the same limitations unless there was a civilization that developed radio technology 100,000 years ago.

Any civilization that far ahead of us could see what a muck we are making of things and want nothing to do with us. Even if a civilization were 100 years ahead of us, that would let us hear their signals and cover a fifth of the galaxy, they would be unaware of us for another 100 years.

As for the bulk of the possibilities for ET, galaxies other than our own, the distances are just too great for us to know before we do ourselves in, making the discussion irrelevant.

And even our intergalactic possibilities are limited to those planets who have evolved a Marconi. So having to search for ET is the one example that works for that religious saw “absence of evidence is not…”

Also going to disagree with MMurray who took exception to the lamp post analogy for searching in Antarctica. Searching for meteorites at the South Pole is not looking under a lamp post but searching for life in them is.

Okay fellas, I'm ready for the woodshed.

Tue, 27 Dec 2011 03:01:12 UTC | #902889

Steve Zara's Avatar Comment 26 by Steve Zara

comment 25 by rjohn19

I'm not thinking about signals from other civilizations, I'm considering signs of activity, such as altered spectra of stars indicating substantial use of "solar" power. I doubt very much that we will hear radio signals from other civilizations because that is a very inefficient way of communicating, and on Earth we are starting to go quiet in radio frequencies as we switch to use of networks for communication rather than broadcasting.

Space is very, very big, but, time is bigger. The galaxy is tens of thousands of light years wide, but billions of years deep in time. Even an incredibly slow process of colonisation would have filled the galaxy on a timescale of millions of years, because of the exponential nature of growth. If any culture had launched replicating probes, they would be here because they would be everywhere.

There has been enough time for an intelligent species to have evolved from worms and filled the galaxy ten times over, even at speeds much, much less than light.

In my opinion, the only reasonable conclusion is that although life might be very common, space-faring technological species are astronomically rare, so rare that at least in our galaxy and its neighbours, we are alone.

Tue, 27 Dec 2011 03:23:51 UTC | #902892

Schrodinger's Cat's Avatar Comment 27 by Schrodinger's Cat

There's a crucial factor in the search for ET, and it's not immediately evident from the Drake equation. And that is.....the average distance between civilisations.

Beyond a certain average distance, we might simply never know for certain if ET exists. If there was on average only one civilisation per galaxy, there would be 100 billion civilisations in the known universe......yet they would mostly remain utterly oblivious to the existence of each other.

That is what I suspect is actually the case. A universe 'teeming' with civilisations the vast majority of whom will conclude they are alone.

Tue, 27 Dec 2011 03:25:00 UTC | #902893

Steve Zara's Avatar Comment 28 by Steve Zara

Comment 27 by Schrodinger's Cat

Beyond a certain average distance, we might simply never know for certain if ET exists. If there was on average only one civilisation per galaxy, there would be 100 billion civilisations in the known universe......yet they would mostly remain utterly oblivious to the existence of each other.

Yes, this is true, but only if civilizations never spread beyond their home star systems, not even as robot probes. Perhaps this is the situation, but it's hard to see how that is the case. We already have robot probes leaving our solar system, and that's an achievement of only the first few decades of space exploration.

It's something of a puzzle!

Tue, 27 Dec 2011 03:31:54 UTC | #902894

DefenderOfReason!'s Avatar Comment 29 by DefenderOfReason!

Comment 27 by Schrodinger's Cat :

There's a crucial factor in the search for ET, and it's not immediately evident from the Drake equation. And that is.....the average distance between civilisations. Beyond a certain average distance, we might simply never know for certain if ET exists. If there was on average only one civilisation per galaxy, there would be 100 billion civilisations in the known universe......yet they would mostly remain utterly oblivious to the existence of each other.

That is what I suspect is actually the case. A universe 'teeming' with civilisations the vast majority of whom will conclude they are alone.

I feel the same way. And to me it seems that basic types of life such as single-celled microbes would be more abundant, of course, than intelligent life. Though S.E.T.I. is a great thing, I think we have a better chance finding evidence for primitive, perhaps even fossilized life, in a rock from, say, Mars than we do finding space-traveling, bi-pedal, grey-skined humanoids.

Tue, 27 Dec 2011 04:05:33 UTC | #902897

severalspeciesof's Avatar Comment 30 by severalspeciesof

Comment 26 by Steve Zara : . Even an incredibly slow process of colonisation would have filled the galaxy on a timescale of millions of years, because of the exponential nature of growth. If any culture had launched replicating probes, they would be here because they would be everywhere.

I'm curious Steve, why would it necessarily have to be exponential growth? Couldn't there be extenuating circumstances (of what I'll admit to not knowing) that would prevent such growth?

Tue, 27 Dec 2011 05:03:45 UTC | #902903