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Using Light's Handedness To Find Alien Life

timothy posted more than 5 years ago | from the let's-skip-some-steps-in-the-middle dept.

Space 210

Rational Egoist writes "Scientists working at the National Institute of Standards and Technology have come up with a novel, easy way to detect life on other planets. Rather than try to measure the composition of atmospheres, they want to look at the chirality of light coming from the planet. From the article: '"If the [planet's] surface had just a collection of random chiral molecules, half would go left, half right," Germer says. "But life's self-assembly means they all would go one way. It's hard to imagine a planet's surface exhibiting handedness without the presence of self assembly, which is an essential component of life."' And they have already built a working model: 'Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to shine light on plant leaves and bacteria, and then detect the polarized reflections from the organisms' chlorophyll from a short distance away. The device detected chirality from both sources.' The article abstract is available online."

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One problem (5, Funny)

eclectro (227083) | more than 5 years ago | (#27698357)

What if the aliens are ambidextrous?

Re:One problem (4, Informative)

Hal_Porter (817932) | more than 5 years ago | (#27698775)

Then this scan won't find them and no preemptive Relativistic Kill Vehicle [wikipedia.org] will be dispatched to their planet.

Re:One problem (1)

LaskoVortex (1153471) | more than 5 years ago | (#27699051)

Then this scan won't find them

The study makes no mention of the false positive rate. We have 7 or 8 (depending on how you count) other planets in our solar system to get a sense of that and they conveniently didn't do the measurements...OK. I'm just guessing they didn't measure the false positive rate. Of course I didn't RTFA.

Re:One problem (1, Interesting)

Anonymous Coward | more than 5 years ago | (#27699101)

You know that's a terrible idea, right? The only situation in which a "pre-emptive" RKV would ever make sense is if you know there's only one other civilization in your segment of the galaxy, and that this civilization is not significantly advanced beyond you.

  Asimov's "angels and apes" observation ruins the latter. Just by probability alone, virtually any species we encounter will be either millions of years behind us, and thus no threat during our species' lifetime, or millions of years ahead of us, in which case their civilization will most likely not be entirely planet-based, and retribution would soon be at hand.

  It's even worse if there are other civilizations out there, undetected. Virtually any RKV is going to be detectable over great distances due to EM radiation, especially infrared. This means that other civs will see the red-hot launch, and see the kinetic effects of the impact, and they will know what we have done. Even if we hide the launch, plain old Newtownian measurements will give them a good line towards the launch point.
  They may decide that such a vicious little species is too dangerous to live, and prepare to wipe us out in a more untraceable, or even more unsurvivable fashion.

  As soon as we launched an RKV, we'd have to start evacuating Earth, and we'd have to spend the rest of our existence running and hiding, digging into the asteroid belts and trying not to emit detectable heat signatures, lest some civ millions of years beyond our own decides to launch hundreds of RKVs, or worse.

  - mantar

Re:One problem (1)

Hal_Porter (817932) | more than 5 years ago | (#27699635)

Actually I was joking about RKVs. What is interesting though is that they technology for an RKV doesn't seem too extreme.

From the RKV article on Wikipedia a 1kg Mass at 99% the speed of light has a energy of 135Megatonnes. The asteroid that killed the dinosaurs had an yield of 75 to 100 million megatonnes. So you'd need a 740 metric tonne projectile at 0.99c

A bussard ramjet would probably have a mass much more than this. I also think that you could probably figure out clever ways to get 740 tonnes to 0.99c if you were a high tech civilisation.

And you never know, maybe the reason we don't see any aliens is because they keep quiet and RKV any civilisations that look like they are near the technological level to RKV them first.

Ok, idle speculation at best.

Re:One problem (2, Interesting)

Ihlosi (895663) | more than 5 years ago | (#27699739)

So you'd need a 740 metric tonne projectile at 0.99c

The problem is that anything above a certain cross-sectional are will probably just disintegrate at 0.99c. At a velocity like that, even the vaccuum of space suddenly becomes quite dense. Heck, you might even run into problems with vacuum energy.

Re:One problem (2)

Hal_Porter (817932) | more than 5 years ago | (#27699841)

At a velocity like that, even the vaccuum of space suddenly becomes quite dense.

That's a plus point if you're using a Bussard Ramjet.

Actually consider the following scenario. You scan for planets with an oxygen atmosphere and then check for signs of a threatening civilisation.

You then launch a Bussard Ramjet to nuke the planet. The spacsehip builds a Krasnikov Tube as it goes. Then you have a route for ground troops or more likely bots to reach the planet quickly post explosion to mop up/enslave any survivors. Most likely humans would survive in shelters from a K-T type impact, but it would definitely mess up their defensive capability. Or you could use a few hundred smaller projectiles aimed at cities to cripple a technological civilisation without destroying the valuable biosphere - that way colonists could arrive without waiting for the biosphere to recover.

I think this is far too ruthless for humans to do and in any case the technology involved is highly speculative and some parts of it are probably not possible, but who says we're the nastiest species out there? Maybe there are much nasier civilisations with the requisite technology.

Best thing about it is that you don't need to worry about the environment - you could wreck the planet building bots, RKVs and ships to get your people to orbit and then head off to the next victim.

Re:One problem (1)

Ihlosi (895663) | more than 5 years ago | (#27699967)

You then launch a Bussard Ramjet to nuke the planet. The spacsehip builds a Krasnikov Tube as it goes.

Whoa, hold on for a minute. The energy required to distort space enough to form a Krasnikov Tube is _huge_. There's no way to accelerate something to 0.99c _and_ form a Krasnikov tube behind it using just a Bussard ramscoop. In fact, it might be impossible just to accelerate to 0.99c without a supplementary power source.

I think this is far too ruthless for humans to do and in any case the technology involved is highly speculative and some parts of it are probably not possible, but who says we're the nastiest species out there? Maybe there are much nasier civilisations with the requisite technology.

Why should a species with access to technology like this limit itself to colonizing previously-inhabited planets? They don't have to care about less-developed civilizations - they could simply pwn the whole galaxy within a few million years or so.

Re:One problem (1)

Extremus (1043274) | more than 5 years ago | (#27699987)

What about multidextrous?

raise your hand... (5, Funny)

Kral_Blbec (1201285) | more than 5 years ago | (#27698363)

if you had to google chirality

Re:raise your hand... (0)

Anonymous Coward | more than 5 years ago | (#27698393)

if you had to google chirality

No, some of us actually read a book once in a while (sorry to burst your bubble there). But I did think something like "chirality: easy to spell, awkward to pronounce."

Re:raise your hand... (1, Funny)

Anonymous Coward | more than 5 years ago | (#27699041)

I'm fairly sure that the OP was making a 'handedness' joke.

Re:raise your hand... (1)

aliquis (678370) | more than 5 years ago | (#27698449)

No, my OS got a dictionary.

Re:raise your hand... (2, Funny)

CRCulver (715279) | more than 5 years ago | (#27699483)

Not me. Four years of undergraduate Greek finally pays off!

How about earth? (0)

guruevi (827432) | more than 5 years ago | (#27698375)

What 'handedness' is earth? I think that because of the vast amount of life on our planet, the handedness would be (statistically speaking) about the same in both directions. According to the article, the handedness gets inherited from parents but it doesn't make clear whether or not it is the same for all life forms.

Re:How about earth? (4, Informative)

Psychotria (953670) | more than 5 years ago | (#27698419)

What 'handedness' is earth? I think that because of the vast amount of life on our planet, the handedness would be (statistically speaking) about the same in both direction

As far as I know, all known life on earth is left handed (i.e. built from left handed amino acids)

Re:How about earth? (0)

Anonymous Coward | more than 5 years ago | (#27698471)

Which means all the right handed amino acids have eloped with the positrons.

Re:How about earth? (0, Redundant)

aliquis (678370) | more than 5 years ago | (#27698475)

Do you know how it is with DL-Phenylanine? I think both forms is supposed to do things in the body but maybe just one occur naturally?

Also for instance R-ALA is supposed to be better than L-ALA but maybe that is because of other things or I don't get it all =P

Re:How about earth? (1)

treddy (1445685) | more than 5 years ago | (#27698509)

Amino acids are "left-handed", but most sugars are "right-handed". Would that even out in the end?

Re:How about earth? (0)

Anonymous Coward | more than 5 years ago | (#27698753)

Just because one contribution is negative and one contribution is positive, it doesn't mean that when you add them you get 0. Example: -2 + 3 = 1.

Re:How about earth? (1)

sFurbo (1361249) | more than 5 years ago | (#27699233)

Not nescecarily, you cannot directly infer the handedness of the reflected light from the handedness of the molecules, L-amino acids and D-sugars might have the same handedness at some frequencies.
But IIRC, the handedness goes way up close to absorption bands, so coloured compounds will account for most of the handedness of the reflected light of a planet. It seems reasonable to assume that the main light-harvesting molecule (chlorophyll in the case of earth) will account for most of the handedness of a planet.

Re:How about earth? (1)

phantomfive (622387) | more than 5 years ago | (#27698701)

That's what THEY want you too think.

Oops, I've said too mu[NO CARRIER]

Re:How about earth? (0, Offtopic)

freedom_india (780002) | more than 5 years ago | (#27699157)

Our schools did NOT teach us much, since teaching us anything beyond adding 1+2 will result in a lawsuit against the school for discrimination.
Idiocracy was a GREAT movie, too bad it didn't do well since people couldn't digest facts.

Re:How about earth? (1)

m50d (797211) | more than 5 years ago | (#27699531)

No, it didn't do well because it sucked. It had a clever conceit, yes, but what happened for the remaining hour or two was your typical action movie, only without the effects budget.

Re:How about earth? (1)

Missing_dc (1074809) | more than 5 years ago | (#27699285)

As far as I know, all known life on earth is left handed (i.e. built from left handed amino acids)

When I read the GP, I jokingly thought to myself, we are inherently evil so we must follow the Left Hand Path.

Funny to see life on this planet is actually wired for evil.

Re:How about earth? (1)

masonc (125950) | more than 5 years ago | (#27699711)

>As far as I know, all known life on earth is left handed
Your left or my left?

Re:How about earth? (1)

Ihlosi (895663) | more than 5 years ago | (#27699761)

Your left or my left?

The other left, of course.

Re:How about earth? (1)

causality (777677) | more than 5 years ago | (#27698431)

What 'handedness' is earth? I think that because of the vast amount of life on our planet, the handedness would be (statistically speaking) about the same in both directions. According to the article, the handedness gets inherited from parents but it doesn't make clear whether or not it is the same for all life forms.

The last several articles that interested me also did a terrible job of actually explaining anything. It's surprising that some of the information omitted consists of very basic details that are directly related to the headline. I hope this isn't the beginning of a trend; infotainment and the average press release have done enough damage to journalism already.

Re:How about earth? (1)

u38cg (607297) | more than 5 years ago | (#27699269)

Lordy. This is some pretty fundamental biochemistry - frankly, it's the sort of thing I would really expect most /.ers to have heard of at some point in their life. Even if you hadn't, it should be fairly obvious with a few moment's thought that certain molecules are going to exist in various transformed versions of themselves, and that selective pressures would inevitably lead to the dominance of one particular type.

However, I'm surprised to learn we collect enough light from a planet to be able to authoritatively assess chirality.

Re:How about earth? (3, Insightful)

Elgonn (921934) | more than 5 years ago | (#27698435)

What 'handedness' is earth?

I have no idea. But I'm not sure it matters. Even if Earth was perfectly neutral the method still works. If the presumption is true then any planet significantly away from average would indicate life. Even if it wouldn't find planets with life that were average.

Re:How about earth? (1)

MaskedSlacker (911878) | more than 5 years ago | (#27698917)

You need to work on your prose; that sentence was a bitch to parse (it wasn't grammatically incorrect, but the simplistic sentence structure and abuse of pronouns made my head hurt). Rewording:

What 'handedness' is earth?

I have no idea, but I'm not sure it matters. The method still works even if Earth is perfectly neutral--if the presumption is true then any planet that deviates significantly from the average must have life; although, those planets might not be typical of ones with life.

Re:How about earth? (5, Informative)

kipton (135584) | more than 5 years ago | (#27698445)

Life on earth exhibits a specific "handedness" or chirality. All DNA twists the same way, for example. Apparently the term for this is homochirality.

http://en.wikipedia.org/wiki/Homochirality [wikipedia.org]

Re:How about earth? (3, Informative)

Anonymous Coward | more than 5 years ago | (#27698467)

The chirality ('handedness') of all known forms of life on earth is the same. Your enzymes can work on certain biomolecules but will not work on their mirror image (a molecule with opposite handedness). Once enzymes are fully formed to do a particular task, there usually isn't much selection pressure to evolve another enzyme to make the same products on mirror image biomolecules. As a result, handedness has been conserved throughout evolution and all organisms share the same handedness with respect to what forms of biomolecules they can process and produce.

Re:How about earth? (0)

Anonymous Coward | more than 5 years ago | (#27698513)

Replying to myself.. bad form, but a modicum of more research reveals that perhaps this explanation is perhaps not as established as I thought. Please do not promulgate.

Re:How about earth? (1, Interesting)

Anonymous Coward | more than 5 years ago | (#27698865)

>As a result, handedness has been conserved throughout evolution and all organisms share the same handedness with respect to what forms of biomolecules they can process and produce.

The fact that all life on earth comprises molecules of the same handedness is one of the myriad of strong pieces of evidence that the theory of evolution is correct in its prediction that all species evolved from common ancestors. The chirality of the basic molecules of life just has to be THE most fundamental characteristic that any lifeform can have. The fact that all life on earth is composed of molecules of the same chirality is a reasonable indicator that all life on earth is descendent from a common set of primodorial self-replicating molecules ... possibly even just the one molecule that started it all off.

Re:How about earth? (0)

Anonymous Coward | more than 5 years ago | (#27699347)

Great**n grand-dad, is that you?

Hmm (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27698387)

I don't get it... maybe I should have read the article and not just the summary.

Define "Short Distance" (-1, Troll)

daveime (1253762) | more than 5 years ago | (#27698427)

And they have already built a working model: 'Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to shine light on plant leaves and bacteria, and then detect the polarized reflections from the organisms' chlorophyll from a short distance away

Newsflash, the closest possible planet that *might* be a candidate is something like 9 light years away.

Bit of a stretch from some science geek shining a torch onto his pet cactus. Smells of a "fund me, or PhD me" non-story.

Re:Define "Short Distance" (3, Funny)

aliquis (678370) | more than 5 years ago | (#27698491)

Smells of a "fund me, or PhD me" non-story.

Also possible: "Buy my freaking huge flashlights!"

Anyway, I guess a star would work as a light source to.

Re:Define "Short Distance" (1)

daniorerio (1070048) | more than 5 years ago | (#27699519)

Of course the star will function as the light source, but as I understand the current method of finding exoplanets is looking for regular fluctuations in star spectra caused by their orbiting planet(s). In order for *this* to work light reflected on the planet needs to be intercepted.

Re:Define "Short Distance" (1)

RsG (809189) | more than 5 years ago | (#27698553)

Actually, rough guess here of course (IANAPHD on the subject), I don't think that's the main problem.

Detecting light reflected from a planet at any interstellar distance is a bigger hurdle. We still mainly detect extrasolar planets indirectly, either by gravitational effects, or by occlusion. (For the curious, this is also where the bias in favour of detecting very large planets arises; the bigger they are, the easier these methods can be used to find them.)

Detecting light from a planet is a pain, since they are not inherently luminous to begin with; they reflect light only. Meaning the more luminous the star is and the closer the planet orbits it, the brighter the planet appears to be. However, as those values rise, so too does the glare of the starlight, making detection harder in the process.

A candidate world needs to be in the habitable zone, reflecting light that can be distinguished from the star it orbits, and detectable to optical astronomy at interstellar distances. There are no telescopes yet that can do this, nor have we found a planet that I know of that fits the above criteria.

If we had the equipment, somewhere to point it, and the means to analyze the image precisely enough, then we could do this. They're basically talking about spectral analysis of telescopic imagery; we've gotten halfway decent at that in the last thirty years. We might even get to use this method in my lifetime.

Re:Define "Short Distance" (1)

dltaylor (7510) | more than 5 years ago | (#27698671)

Transit.

As a planet passes between us and the star some (very) small amount of light from the star passes through its atmosphere, including incident grazing of the surface. If/when the detectors on a space telescope are sensitive enough, then, during transit they may detect a change in the distribution of polarization. This may also be easier when the transit is either just beginning or just ending, since the main source of light will be mostly "to the side" of the planet.

As the sensor density increases, we should also be able to look at the small number of the atmospherically-affected nodes and ignore the surrounding unobstructed stellar light nodes.

Re:Define "Short Distance" (1)

Nazlfrag (1035012) | more than 5 years ago | (#27699149)

The habitable zone is not fixed in stone, we could perhaps find life outside of it. It would be worth examining chirality for any planet. Still, not much can be done until advances in astronomy let us get a decent view of these exoplanets.

Venus and Mars are 9 light years away? (1)

denzacar (181829) | more than 5 years ago | (#27699693)

When did that happen and why wasn't I informed about it?

Re:Venus and Mars are 9 light years away? (1)

Ihlosi (895663) | more than 5 years ago | (#27699717)

When did that happen

Yesterday.

and why wasn't I informed about it?

Well, if they're 9ly away, then the signal will take another years to get here, of course.

Not any time soon... (1)

le_sean_moon (1519717) | more than 5 years ago | (#27698447)

Ummm... "They already have a working model". That sort of made it seem like you know, maybe they had something that they could use at a range of more than a few FEET. This is a long way off. And maybe not even theoretically sound? Sounds little early to be news.

PSST! (1)

denzacar (181829) | more than 5 years ago | (#27699713)

Sounds little early to be news.

One of the points of "the news" concept is the delivery of the information as early as possible and as soon as it happens.

That is one of the reasons we call it "the news" and not "the olds".

Quirks and Quarks Had a Good Story about This (4, Informative)

nz17 (601809) | more than 5 years ago | (#27698465)

CBC's science program Quirks and Quarks had an interesting story about the handedness of molecules [www.cbc.ca] that it played last month. (Audio available in Ogg Vorbis) It provides a nice, friendly introduction to this topic.

Aliens, we are coming! (2, Funny)

MikeOtl67of (1503531) | more than 5 years ago | (#27698473)

This sound very interesting. Maybe there are business opportunities with Aliens. What do you think they would be ready to buy from us? Maybe something to show an even distrubution of chiral molecules could avoid their friends on other planets to also get discovered by nasty sellers from Earth, but I am not sure we should sell such a thing. Any valid business idea?

Very punny :P (4, Funny)

Merakis (959028) | more than 5 years ago | (#27698479)

So, to sum up the article... Chirality is not dead!

Scanning for lifesigns (2, Interesting)

Anonymous Coward | more than 5 years ago | (#27698489)

One more trek concept brought to real-life, yay! (The other one being the communicators on TOS)

- AC, patiently waiting for warp drives

Wow (4, Insightful)

ShooterNeo (555040) | more than 5 years ago | (#27698501)

This just might work. It'll take incredibly good optics, of course, and the chirality of the light from these distant planets might be lost when the light goes through the earth's atmosphere. Might take a gigantic telescope in outer space.

Re:Wow (0)

Anonymous Coward | more than 5 years ago | (#27698709)

I don't believe circularly-polarized light can have its handedness changed without reflection.

Re:Wow (2)

zeptobyte (1140111) | more than 5 years ago | (#27698887)

If only we had one of those..

Re:Wow (1)

rts008 (812749) | more than 5 years ago | (#27698975)

Might take a gigantic telescope in outer space.

What would be really cool would be able to build one of those array type telescopes(really, outrageously Humongus sized) at one of the lagrange points.

Re:Wow (2, Funny)

sFurbo (1361249) | more than 5 years ago | (#27699253)

(really, outrageously Humongus sized) at one of the lagrange points.

No, please don't give them any more stupid ideas for what to call large telescopes [wikipedia.org]

Re:Wow (0)

Anonymous Coward | more than 5 years ago | (#27699093)

Soooo.... Hubble, Chandra, James Webb, Spitzer, Kepler, COROT type gigantic outer space telescope?

Ah, life-signs! (0)

Anonymous Coward | more than 5 years ago | (#27698517)

I always wondered how they were going to do that.

I'm sceptical.... (5, Interesting)

Genda (560240) | more than 5 years ago | (#27698551)

The whole reason that life produced molecules of fixed chirality is that molecules precursing life are generated in cold gase nebulae that are often effected by radiation from young stars which have a particular chirality. That is to say, the cold nebulae that was the precursor of the Sol system, had light whose chirality precipitated right handed sugars and left handed amino acids.

A planet let's say, made of hydrocarbons and complex organic molecules that formed in such a cold dark nebulae, might have no life, but it's chemistry would in fact have fixed chirality. That is to say, someone needs to point the first instance of this instrument at Titan, a place where we are pretty sure no surface life (as we know it) might exist, but whose surface chemistry may very well have preserve some of the chirality of the nebulae that formed the Sol system. If we receive significant chirality frozen in the Titan surface, it would be a strong indicator that this test is less than optimal for finding earth like planets.

Re:I'm sceptical.... (1)

MichaelSmith (789609) | more than 5 years ago | (#27698695)

If Titan has mixed chirality, would this reduce the efficiency of agriculture on that planet? I am thinking that we might try to use indigenous molecules to grow food. If the mix was 50% presumably only half the molecules would work for us.

Re:I'm sceptical.... (3, Insightful)

MaskedSlacker (911878) | more than 5 years ago | (#27698959)

Not all molecules are chiral. Simple molecules which form the raw materials for life forms are not themselves chiral because they are symmetrical (O2, H20, NH3, CO2, etc; chirality is only possible for asymmetric forms molecules). The simplest solution the problem you describe is to introduce simpler lifeforms from earth--bacteria or archaea to start producing organic molecules of the correct chirality from the raw material precursors.

Re:I'm sceptical.... (1)

Sibko (1036168) | more than 5 years ago | (#27698757)

Or it might tell us that there's life on the surface of Titan...

Re:I'm skeptical.... (5, Informative)

Richard.Tao (1150683) | more than 5 years ago | (#27698995)

You appear to be wrong on a few big things...
-most compounds are not chiral, so even if a dead planet had some pure enantiomers, they would be insignificant compared to one with life, life produces a crazy large amount of them
-no one has quite figured out why life has the handedness it does, some say it could be because of silicon catalyzing a certain handedness, others disagree, there is not an answer to this question yet, but it makes sense that life would evolve to have a specific handedness so all the parts could be interchangeable and we don't have bizzaro ecoli floating around that can exchange DNA with normal ecoli
-since when does polarized light catalyze chiral reactions?? UV light can catalyze reactions, and chiral molecules can cause a reaction to form with a specific handedness, but only chiral MOLECULES can catalyze reactions to cause a more enantiomericly pure product

Re:I'm skeptical.... (3, Informative)

sFurbo (1361249) | more than 5 years ago | (#27699267)

-since when does polarized light catalyze chiral reactions?? UV light can catalyze reactions, and chiral molecules can cause a reaction to form with a specific handedness, but only chiral MOLECULES can catalyze reactions to cause a more enantiomericly pure product

Not quite, IIRC, there are examples of some reactions with polarized light which gives ~1% excess of one enantiomer. It has been hypothesized to be the origin of the handedness of life. But in itself, it will not give enough of a excess to be meassured with this technique.

Re:I'm skeptical.... (2, Interesting)

TeknoHog (164938) | more than 5 years ago | (#27699305)

-no one has quite figured out why life has the handedness it does

I recall a theory that it is due to the slight asymmetry in weak interaction, but I've forgotten the exact mechanism. This asymmetry exists basically everywhere in the universe, but as life is self-replicating, it can amplify the effect to a great extent. Here's the first reference found via quick googling:

http://www.springerlink.com/content/0743577n4716u23j/ [springerlink.com]

Re:I'm skeptical.... (1)

Jeff DeMaagd (2015) | more than 5 years ago | (#27699339)

I recall a story about it, someone in this thread linked to a Quirks and Quarks story where it turned out that comets have been shown to have a tendency to lean towards containing amino acids with a certain handedness. The thought is that life likely formed with that handedness because there were more amino acids to work from.

Re:I'm skeptical.... (2, Interesting)

Cyberax (705495) | more than 5 years ago | (#27699757)

Also, don't forget racemization (http://en.wikipedia.org/wiki/Racemization) - a lot of enantiomeric compounds can spontaneously switch chirality (it's actually a big problem for some extremophile bacteria - they replicate so slowly because they have to expend energy to repair damage from racemization).

Re:I'm sceptical.... (2, Informative)

endall (148631) | more than 5 years ago | (#27699193)

According to this article (http://asunews.asu.edu/20080229_pizzarello [asu.edu] ), an un-contaminated meteorite was was found to have amino acids with mixed chirality, but with a bias towards the left-handed (up to 15%), not the 50%-50% suggested in the article linked in the submission. So to some extent, this supports what you said.

Even so, the technique described in the submitted article could work. It's all about signal to noise. If some feature of a planet reflects vastly more chiral bias than a rocky moon or asteroid in the same system, that could indicate that it harbors life.

Life Jim, but not as we know it! (4, Informative)

Omnifarious (11933) | more than 5 years ago | (#27698559)

First, for those who are wondering "What the heck is chirality?". So, you have left handed gloves and right handed gloves, and you can't transform one into the other without doing something like flipping it through a fourth spatial dimension (strangely, flipping it through the time dimension will result in an opposite handed glove traveling backwards in time that's made of antimatter) or turning it inside out. Proteins, also being three dimensional objects, are the same way. And there is a convention for deciding whether a given molecule is right or left handed. Chemical processes tend to produce equal numbers of left and right handed versions. Biological processes on earth tend to produce almost exclusively right handed molecules.

I didn't know this before reading the article, but it makes sense... the chirality of a molecule apparently affects the polarity of the light that is reflected from it or transmitted through it.

Now, to talk about what I think of the article...

Scientists make too many assumptions. Life requires self-replication... that's it. It doesn't require water and it doesn't require chirality. It doesn't require a whole host of things that scientists tend to assume it requires simply because it's a characteristic we've observed about life on earth.

But, I will agree that if they can detect the predominance of one particular chirality then that's a strong indicator of some life-like process at work.

That absence of chirality is no indicator that there isn't life. It just won't resemble the life we have here on earth.

It may be possible to prove that self-replication within a given system (like chemistry, for example) is very hard without certain conditions. I'm willing to believe, for example, that non-carbon based life that primarily functions chemically is highly unlikely because carbon is such a fantastically versatile atom chemically speaking.

Of course, there might be life based on nuclear processes [wikipedia.org] or, even farther fetched, life based on gravitational processes. As support for the second, galaxies have a very complex lifecycle in which supernovas and black holes play key roles. They eat the thin gas left over from the big bang, and metabolize it into new stars with supernovas and black holes. I'm not sure where self-replication fits into that picture so galaxies may just be metabolism absent a mechanism for self-replication (i.e. engines) and hence not really alive.

Life based on nuclear processes or gravity is certainly not going to exhibit any chirality signature, nor require water or even carbon.

But, as I said, I will agree that a chirality signature is strong evidence for chemistry based life. I just don't think its absence is strong evidence against life.

Re:Life Jim, but not as we know it! (1)

RsG (809189) | more than 5 years ago | (#27698635)

I'll avoid the obvious pitfall of pointing out that we can't conclusively prove a negative. I think that, at any arbitrary point in the future, we'll either have found non-carbon life, or we'll still be arguing over it's existence. Science fiction of the thirtieth century should be an interesting read :-)

However, we need to look for the carbon-based life first, regardless. We currently have a sample size of one for livable planets, and that tells us next to nothing about the rest of the universe. Is our world unique, is it vanishingly rare, or are worlds like it common as dirt?

Once we've addressed this, at least partially, we'll have a better handle on asking what other forms life can take. Even a single instance of extraterrestrial life would increase our sample size by 100%, a start in the right direction.

Re:Life Jim, but not as we know it! (1)

MichaelSmith (789609) | more than 5 years ago | (#27698641)

Arthur C Clarke wrote a great story about this.

Spoiler Alert

An engineer gets exposed to an intense magnetic field during an accident in a power station. While recovering from his injuries it turns out that he can no longer extract energy from normal human food. The theory is that the field created a volume of four dimensional space within which he rotated before the power was removed. Faced with the prospect of starving to death he agrees to repeat the exposure in the hope that he will get rotated around the fourth dimension again. Unfortunately he translates along that dimension during the process and reappears inside after the power station after it has been put back into operation.

Re:Life Jim, but not as we know it! (0)

Anonymous Coward | more than 5 years ago | (#27699167)

"Technical Error".

Re:Life Jim, but not as we know it! (1)

TapeCutter (624760) | more than 5 years ago | (#27699283)

"Scientists make too many assumptions."

I disagree, enumerating and testing assumptions is at the core of their job description. They don't have any examples of "life as we don't know it" so they cannot make ANY TESTABLE ASSUMPTIONS about it, if scientists cannot test it then it's NOT science. This probably explains why your dragon's egg link is classified as fiction.

Life requires self-replication... that's it. It doesn't require water and it doesn't require chirality. It doesn't require a whole host of things that scientists tend to assume it requires simply because it's a characteristic we've observed about life on earth.

Crystals self replicate on the atomic scale so I think your definition requires some work. The characteristics we have observed on Earth are the ONLY KNOWN characteristics for differentiating between life and "something else". Sure there may be "life as we don't know it" somewhere, it could even turn out to be god, but why waste telescope time and probes looking for something with unknown characteristics? It's much, much, much, more efficient to SCIENTIFICALLY narrow the search to "life as we know it". You can prove this efficientcy claim to yourself by simply picking up a rock and listing it's infinite set of unknwon characteristics.

It's a shame you felt you had to take a poke at scientists since you are obviously an intelligent life form and the rest of your post contains some interesting speculation.

Re:Life Jim, but not as we know it! (1)

Omnifarious (11933) | more than 5 years ago | (#27699687)

Crystals self replicate on the atomic scale so I think your definition requires some work.

This is true. I believe there is a more formal definition out there involving the ability to evolve [wikipedia.org] . But defining exactly what that means can be a bit tricky.

I disagree, enumerating and testing assumptions is at the core of their job description. They don't have any examples of "life as we don't know it" so they cannot make ANY TESTABLE ASSUMPTIONS about it, if scientists cannot test it then it's NOT science. This probably explains why your dragon's egg link is classified as fiction.

...

It's a shame you felt you had to take a poke at scientists since you are obviously an intelligent life form and the rest of your post contains some interesting speculation.

I disagree. For example, I think looking for chirality is a much more general, and a stronger test than looking for water. I think what you want to look for is evidence of complex self-ordered systems.

I do agree that looking for life that's like the life we already have first hand examples of is the easiest thing to do, and probably what we should be concentrating our efforts on. I just dislike the intellectual laziness inherent in statements that declare things like "Life requires water.". It constrains people's thinking in ways that make it less likely that people will come up with interesting and novel ways to look for life because it embeds preconceptions in their notion of what they're looking for.

Of course, much of what I perceive as intellectual laziness could just be the result of bad and/or imprecise science reporting.

I do not mean to put down science as a whole. I think it is our absolutely best and most useful tool for learning about the world around us. I do think though that there is an unfortunate tendency to repeat dogma as science (i.e. they are not the 'laws of physics', they are simply the best mathematical model we've yet discovered for what we've observed so far), and I don't like that because I think it impedes scientific progress. Constrained and focused observational efforts are wise, constrained thinking is not.

Re:Life Jim, but not as we know it! (2, Funny)

4D6963 (933028) | more than 5 years ago | (#27699317)

So, you have left handed gloves and right handed gloves, and you can't transform one into the other without doing something like flipping it through a fourth spatial dimension

Little known fact : that's actually how right hand gloves are made. Turns out that using a fourth spatial dimension is cheaper than machinery to build both types of gloves.

Re:Life Jim, but not as we know it! (1)

Omnifarious (11933) | more than 5 years ago | (#27699705)

Little known fact : that's actually how right hand gloves are made. Turns out that using a fourth spatial dimension is cheaper than machinery to build both types of gloves.

You know, I was wondering about that.

I thought for awhile that maybe what they did was take the left hand glove at some point in the future and flip it into antimatter. And this would be safe because, you know, it was in the future and it was already known when the gloves would join together in the past and so it was safe to send an antimatter glove back because causality dictated that it would never react explosively with its environment.

But I guess flipping them through a fourth spatial dimension is easier and less error prone.

Re:Life Jim, but not as we know it! (1)

Corporate Troll (537873) | more than 5 years ago | (#27700055)

Life requires self-replication...

According to your definition "fire" would qualify as life. When I was in highschool, the definition given to us was the 7 points in the wikipedia article [wikipedia.org] .

I'm no biologist, but replication only isn't enough for life.

This is all well and good, but... (3, Interesting)

cyn1c77 (928549) | more than 5 years ago | (#27698605)

If we can't actually go visit any aliens we detect because they are light years away, it is just going to drive us batty.

And I don't really want the aliens coming to visit us either, because that would mean they were more technologically advanced than humans. And the inferior species always seems to end up as food or raw material. Come on, even Hollywood has figured this out!

Re:This is all well and good, but... (0)

Anonymous Coward | more than 5 years ago | (#27699775)

We have to devise a planet-wide filter that hides our chirality signature.

Re:This is all well and good, but... (0)

Anonymous Coward | more than 5 years ago | (#27699911)

But it would take them so long to get here that we'd either have progressed to their level of technology by then, or we'd be dead.

A sufficient, but not necessary condition for life (2, Interesting)

dido (9125) | more than 5 years ago | (#27698631)

I suppose that if you were to detect chirality bias in the light coming from a particular planet, that would probably be sufficient to conclude that there might be some form of life on that planet that was causing that particular bias. However, it doesn't seem that it's a necessary condition, i.e. not detecting chiral bias might mean that there might after all be some very strange life form on the planet whose chemistry made use of both left and right handed molecules. In fact, there are some strange life forms on Earth, notably archaea [wikipedia.org] , that actually use right-handed proteins in some aspects of their biochemistry, quite unlike all other life forms found on earth, which use left-handed proteins exclusively.

Test it on Europa (3, Insightful)

kn0tw0rk (773805) | more than 5 years ago | (#27698711)

Surely this would be a good test to check out Europa?

Even though the ice crust might obfuscate things, if the light was from reflected from the area of a crevice/crack then there would be elements (or the lack thereof) in the frozen water that give some indication.

Re:Test it on Europa (0)

confused one (671304) | more than 5 years ago | (#27699085)

"All these worlds are yours except Europa. Attempt no landing there."

hmmm i guess we are a few lightyears away... (0)

Anonymous Coward | more than 5 years ago | (#27698803)

a slight angle difference of even a few seconds at the source planet, we will need to have the receivers millions / billions of light years away from earth...

or triangulate the ones we receive on earth....

Let Me Guess... (1)

hyades1 (1149581) | more than 5 years ago | (#27699005)

Based on the little-known work of Dr. Peter Pullet-Wildly, it should be possible to detect not just alien life, but alien intelligence. Because if you encounter left-handed rather than right-handed chirality, it feels like somebody else.

Unless you're a southpaw, of course.

Re:Let Me Guess... (1)

shmooattack (1482261) | more than 5 years ago | (#27699155)

Probably little-known for a reason.

Sure, eventually we'd like to know the nature of the life we find... whether or not they have cars, jetpacks, or nuclear weapons to destroy all of humankind. I think it's ok to start with the small stuff. There's no reason to start building a laser-based chupacabra containment machine until we definitively determine they exist, don't you think?

Well... (1)

Richard.Tao (1150683) | more than 5 years ago | (#27699053)


That would be an immense technological feat. Where already doing something similar with a telescope that looks for planets by seeing the slight dimming of stars caused by the planet eclipsing then star. It was compared to seeing a fly pass by a headlight a mile away.
Detecting a minor variation in the handedness of the light that the planet happens to catch on the surface then reflect back into space, which is light years away, whose feeble light is VASTLY over powered by it's home star. I'm guessing will have to wait many years for this, and there maybe a more feasible technique that comes along before it.

Instructions on doing something similar at home... (1)

Centurix (249778) | more than 5 years ago | (#27699061)

By using a combination of rice paper and domestic household bleach you can detect if a planet is either Regular or Goofy footed...

A good tool for the toolbox. (1)

Ihlosi (895663) | more than 5 years ago | (#27699089)

I like the idea. It looks like an execellent tool to add to the toolbox for determining the probability of an extrasolar planet harboring an ecosystem.

Of course, an alien ecosystem could have evolved to use both handednesses, but the information that one handedness is predominant on the planet is a strong hint that there's something unusal going on there. Same goes for the detection of unusually large quantities of unstable substances (oxygen, halogens, etc) in the atmosphere of the planet.

Heavy handed approach not working (1)

Orlando (12257) | more than 5 years ago | (#27699115)

Using Light's Handedness To Find Alien Life

Because the heavy handed approach we've taken so far is not working?

Oh wait...

It's the approach that's novel, not the idea. (1)

shmooattack (1482261) | more than 5 years ago | (#27699133)

The notion that chiral molecules polarize light is not the contribution of this research. Anyone that has taken an introductory organic chemistry course will know this property of chiral molecules to be true. Also, those involved with "origins of life" research are certainly aware that looking for this type of light might be our best bet at discovering alien life. The idea is not novel. The approach is. The paper they reference is titled: "Detection of circular polarization in light scattered from photosynthetic microbes" Which focuses on the approach to detection, not the novelty of what the detection might implicate.

Implication / equality (0)

Anonymous Coward | more than 5 years ago | (#27699151)

I hate to rain on your parade, but while this could provide an interesting test to filter out potential candidates for life-bearing planets, it's not enough to find life itself.

Put another way: the fact that life implies chirality doesn't mean that chirality implies life.

And that's assuming that "life implies chirality" is even true. We know it is here, but are we really so sure it'll ALWAYS be true EVERYWHERE? What reason to we have to expect other life forms' biological markup to be any similar to our own? It might well be, but then again, it might well not.

Statements like "it's hard to imagine" (in this case, "how X could be true without Y") should make you skeptical, anyway. Yes, it IS hard to imagine. Lots of things are, but that doesn't mean they can't be true.

Sci-Fi Much? (0)

Anonymous Coward | more than 5 years ago | (#27699169)

I wonder if this technology could be used to create a "life-signs" detector (ala Stargate Atlantis)?

Rather thin (1)

jandersen (462034) | more than 5 years ago | (#27699213)

That is a very weak cup of tea. For one thing, I can't see what is new in this; we have been able to do this sort of thing for decades. Also, I don't think we would be able to detect life on Earth using this method, let alone another planet lightyears away. The biomass on Earth is actually rather minute compared to the whole of the atmosphere or the oceans, so the signals would be weak, even for our own planet; and there are many things between us and our neighboring stars that could both polarise and depolarise the light on the way, thus scrambling the signal.

To me this sounds like cartoon science.

The assumption here... (3, Interesting)

exp(pi*sqrt(163)) (613870) | more than 5 years ago | (#27699251)

...is that life forms a kind of amplification process.

If you have some random soup of molecules formed by abiotic processes then apart from some small biases brought about by parity-violating fundamental physics we expect complete symmetry between left- and right-handed molecules.

But life, arguably, forms a kind of amplification process. Competition between molecules with different chirality might serve to increase any initial small difference between one group and another. So what starts as almost exact symmetry results in a planetwide bias one way or the other.

But there are two issues.

(1) Could such a planetwide bias show up strongly enough in the polarisation of light reflected from the planet. It seems very unlikely given how messy a planet is. Let's say you pick a million different types of molecule than come in chiral pairs and for each molecule pick one of the pair, discarding the other. Now jumble up many different copies of each of these molecule types. Your chances of detecting chirality from afar is minimal even though, in some sense, the mixture is perfectly chiral, because of the overall randomness of the mixture.

(2) Could any other physical processes cause such amplification? The answer is yes. For example some kinds of crystal growth can result in homochirality.

So I'm pretty sceptical despite the idea being neat.

we search for life with lanterns (1)

tommten (212387) | more than 5 years ago | (#27699665)

reflections of light
our query: is it life jim?
- not as we know it

What it is (0)

Anonymous Coward | more than 5 years ago | (#27699859)

In layman's terms
Rather than the frequency/ wavelength of light from a planet, , they're ar looking at the Modulation of it , phase / amplitude and distribution of that light
May I coin the phrase 'life Modulation '?

Meteorite organics show chirality (1)

Richard Kirk (535523) | more than 5 years ago | (#27700015)

Material from space has already been shown to exhibit chirality. There's quite a nice review on...

http://scienceandreason.blogspot.com/2009/04/amino-acid-chirality.html [blogspot.com]

We do not know that this chirality comes from life. People have presented this as evidence that life exists in space, that life was seeded from space, and all sorts of other stuff. All we actually seem to know is that some stuff out there shows a handedness. If your light is passing through chiral material in space it will pick up a polarization.

This is not to say that this is not a test. If we find a star with planets, and one of the planets reflects more of one circular polarization than the other, then whatever it is that was doing it is probably on or about that planet. A good start would be to see whether we can pick out earth from space this way. I think they are planning to do just that.

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