Using Light's Handedness To Find Alien Life

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."

Comments

One problem

[eclectro]

What if the aliens are ambidextrous?

Re:One problem

[Hal_Porter]

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

Re:One problem

[LaskoVortex]

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

[Anonymous Coward]

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

[Hal_Porter]

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

[Ihlosi]

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

[Hal_Porter]

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

[Ihlosi]

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

[Extremus]

What about multidextrous?

Re:One problem

[Anonymous Coward]

You'll need much more than 0.99c to have that kind of problem. At 0.99c, the length contraction factor is about 7, so the density of space increases only about 7 times.

Re:One problem

[Jurily]

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

So you need that much energy to set it on course. Any ideas? Blow up 1,5 million Tsar Bombas?

Also, doesn't mass increase at non-relativistic speeds?

Re:One problem

[Hal_Porter]

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.

Actually you'd don't need the Krasnikov tube. The whole civilisation could travel in Bussard Ramjets. Why do it? Why invade countries for gold, oil or slaves when you could stay home and live sustainably?

Everything is about resources. In my hypothetical planet hopping civilisation planets provide the resources to build more ramjets. You'd send down engineers and machines, they'd strip the planet and turn it into another ships. The reason you target planets with technically advanced civilisations is that they by definition have the resources you need. Maybe you need to fight wars for ideological reasons too or the people in power might want the glory of 'civilizing the barbarians' or making them worship the right god.

It's not like human civilisations have never done this on Earth. In fact pretty much every famous civilisation was to some extend imperialist and didn't just stay home and live sustainably. Maybe there are predator civilisations and prey ones and the predatory ones more fit in Darwinian terms - i.e. they spread more widely, consume the prey and end up writing the history books and portraying themselves as superior.

Certainly the Europeans and Americans have historically been highly predatory and have obliterated scores of more peaceful but 'inferior' civilisations here on Earth. Why is a stretch to think that you couldn't do this on a bigger scale?

Something else occurs to me - you could build lots of Orion type craft to get the loot into orbit since you don't care about the biosphere after you leave. Once in orbit you build a ramjet and head off with lots of new ships plus anything of value (resources or slave labour) from the planet you sacked.

Re:One problem

[Anonymous Coward]

Same as when they turn out to be ambisinister. Could be worse though. They might be ambisinister decapollex, in which case you won't find them because they've most likely gone extinct a long time ago.

Re:One problem

[Anonymous Coward]

I didn't know Krasnikov tubes were part of the general vocabulary ... are you in theoretical physics, or was this used somewhere else?

Re:One problem

[Ihlosi]

Why do it? Why invade countries for gold, oil or slaves when you could stay home and live sustainably?

The question is reversed in our case. Why go through all the trouble of exterminating less advanced civilizations, when the planet they're on only contains a tiny fraction of the "resources" in their solar system?

In my hypothetical planet hopping civilisation planets provide the resources to build more ramjets. You'd send down engineers and machines, they'd strip the planet and turn it into another ships. The reason you target planets with technically advanced civilisations is that they by definition have the resources you need.

The rest of their solar systems contains a couple of orders of magnitude more resources. Why ignore them?

It's not like human civilisations have never done this on Earth. In fact pretty much every famous civilisation was to some extend imperialist and didn't just stay home and live sustainably.

It's not about living sustainable. The approach I suggest is far from that, it's about colonizing the whole galaxy (exponential growth is, by definition, not sustainable in the long term).

Certainly the Europeans and Americans have historically been highly predatory and have obliterated scores of more peaceful but 'inferior' civilisations here on Earth. Why is a stretch to think that you couldn't do this on a bigger scale?

Because on Earth, 'inferior' civilizations were densely packed. In the galaxy, you'd have to spend way too much time and effort to track them down. Just start colonizing everything and quarantine every inhabited planet you find (make it a big zoo or something). You'll end up with a couple of orders of magnitude more resources than if you focus on plundering inhabited planets.

Something else occurs to me - you could build lots of Orion type craft to get the loot into orbit since you don't care about the biosphere after you leave.

If you stick with uninhabited planets, you won't even have a biosphere to deal with (so no risk at all of any kind of contamination). In fact, if you stay away from large gravity wells, sending more stuff into space will get even easier.

Re:One problem

[elrous0]

It worked on the Martians, didn't it?

Stupid native Martians. Always whining that people don't treat their ancestor's bones with respect.

Re:One problem

[maxwell demon]

Actually you'd don't need the Krasnikov tube. The whole civilisation could travel in Bussard Ramjets. Why do it? Why invade countries for gold, oil or slaves when you could stay home and live sustainably?

Simple: Because on earth, about everywhere where ressources are there are also people, nations, etc. So your only chance to get ressources (except for buying, of course) is to invade other countries. OTOH, there are lots of ressources in space which are not on habitable planets, indeed, most are. So there's no reason not to exploit those, too. Only other civilizations which are also advanced enough to exploit those "non-inhabitable ressources" would be a possible war target, because they are the only ones which might get in your way (by themselves exploiting those ressources).

Only after the advanced civilizations have used up all the ressources in space (which are more than on habitable planets), they would get interested enough in the ressources of habitable planets to start a war against those. But until then, they are probably advanced enough that they don't need to: They just use advanced armour, and otherwise simply ignore those lesser civilizations on those planets. Not that those civilizations would likely survive that anyway, but it would just be waste of energy to actively fight against them.

Re:One problem

[maxwell demon]

Also, doesn't mass increase at non-relativistic speeds?

Well, actually, mass doesn't increase at all with speed, but even if you use the outdated concept of relativistic mass, then nonrelativistic speed is defined as speed where relativistic effects are negligible. So no, there's no mass increase at non-relativistic speeds.

Of course, 0.99c is clearly a relativistic speed anyway. :-)

Re:One problem

[pleappleappleap]

Mass doesn't increase at *non*-relativistic speeds. At non-relativistic speeds, the conservation of mass applies.

Anyway, it wouldn't require anything like blowing up a giant bomb. You don't need to get the rate of acceleration of the projectile very high. You just need to accelerate it for a long time.

Re:One problem

[geekoid]

AS long as the disintegrated pieces(Atoms) hit the planet at that speed, the planet will still be dead.

Of course, at that speed, you really only need something the size of a softball to cause the atmosphere to explode and kill most, if not all life.

Re:One problem

[geekoid]

"se. Why go through all the trouble of exterminating less advanced civilizations, "

  because they are competitors for resources.
If they are at a primate level, then fine, but if they are cusping on space technology then you ahve to do something.

Either kill them, or infiltrate them and co-op there society.

Also, have a habitable planet ready to go is nice.

Re:One problem

[Jurily]

Mass doesn't increase at *non*-relativistic speeds. At non-relativistic speeds, the conservation of mass applies.

Typo. I meant relativistic.

You don't need to get the rate of acceleration of the projectile very high. You just need to accelerate it for a long time.

Acceleration requires energy, no matter the rate. As you apply energy, the object's mass increases as well, not just its speed, though it's insignificant at low speeds, so you get Newtonian physics if you disregard it. At speeds comparable to c, however, the mass increases significantly, so you have to add even more energy to accelerate it further. This is why you can't reach light speed: at c, the mass, and thus the required energy would be infinite.

See here and play it out as v approaches c.

Re:One problem

[Seedy2]

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.

Maybe the Dinos annoyed someone who flung a RKV at them... seems to have worked. :)
And without trashing ALL life on the planet, earth has recovered nicely.
Too bad we are messing it up so much... hmm.

Re:One problem

[Anonymous Coward]

because they are competitors for resources.
If they are at a primate level, then fine, but if they are cusping on space technology then you ahve to do something.

You're still missing Asimov's "Angels or Apes" factor. Imagine the sum of our species' total history laid out on a yardstick from the time we were recognizable as semi-intelligent creatures a couple of million years ago, leading on into the distant future. On the left hand you'd have a foot or so marked "apes" wherein our species (and its large-brained immediate predecessors) used very little recognizable technology and was only barely sapient. Then after those there's a tiny hundredth of an inch marked "Men" which represents the past 4000 years, which is followed by the remaining two feet, standing for millions of years marked "Angels" which represents the period wherein our technology will advance so far as to make our society almost unrecognizable to our predecessors, and our abilities far above those of men and apes.

  Now imagine you're an alien species discovering this planet at some point in our history. (or conversely that we are discovering them) Odds are best you'd spot our world during the hundreds of millions of years when there wasn't any highly intelligent life (apart from cetaceans in a recent few million years) at all, but we'll ignore that, since we're talking about encounters with intelligent, tool-using life. Such a discovery could happen at any point along that ruler. What are the odds that it would land on or near that little bitty mark in the middle where we would be just advanced enough to be a competitor, but not so far advanced as to be well beyond anything they could compete with? And no matter what point they are at in their planet's lifespan, the same problem occurs.

  Bablyon 5 got around this problem by having the Shadows come out every 3000 years and blow everything up. Star Trek mostly ignores it, except briefly in Star Trek IV.

  Waging interstellar wars is a really bad idea, because the odds are pretty good there will be an interstellar species out there hundreds of millions of years older than you, which may be quiet because they're expecting, from experience, to see vicious little planet-killers to pop up now and then. And when such a species appears, they probably extirminate them.

  - mantar

Re:One problem

[Hal_Porter]

I think you're looking at things from a Carl Sagan like perspective where advanced civilistations are highly rational and benign. The real world isn't like that at all. The Europeans and the Japanese both had the technology to travel long distances and convinced themselves that they were some kind of master race, destined to rule what - to them at least - was the universe.

Most European cultures never met a civilisation which could stop them and built empires and got rich. The Japanese and Germans tried the same thing but much too late and were stomped by the Americans and their allies. Still they were very unlucky in meeting a much more advanced and fundamentally more principled competitor.

In my scenario it's quite plausible that a civilisation bent on slash and burn exploitation could grow to the point of invincibility before meeting a peer competitor. Now inside the civilisation people may worry about the wisdom of continued conquest, but no one would listen while it still seemed to be working. It's quite plausible, if life exists ubiquitously, that the universe is full of civilisations trying the same sort of trick, just like Earth upto 1900 was.

Which would explain the Fermi Paradox - advanced civilisations exist but those that broadcast their existence are quickly stomped by others.

Re:One problem

[Anonymous Coward]

AS long as the disintegrated pieces(Atoms) hit the planet at that speed, the planet will still be dead

The point was that nothing with that amount of rest mass is going to hold together at ultrarelativistic speeds.

There are several ways to consider why - here are two:

1) in the inertial frame in which the "softball" is at rest there is a huge dipole anisotropy in the ambient photons that we (not moving relativistically) see as the cosmic microwave background radiation, which has a small dipole anisotropy. At ultrarelativistic speeds, the small directionality is magnified to ELF radio in one direction, high frequency gamma radiation in the other. A similar dipole anisotropy happens in the background neutrino field. Since the fluxes are quite large, the high mass-energy gamma rays and high mass-energy neutrinos will quickly dismantle composite particles that experience the electromagnetic and weak forces. Vacuum fluctuations will quickly dismantle composite particles that experience the strong force, too. Because of the directionality of the high energy particles, ultimately conservation of momentum will cause the "primitivized" mass-energy of the "softball" to adopt a kelvin wake pattern (or if you prefer, to migrate into the umbra and penumbra of the central mass-energy).

2) At ultrarelativistic speeds the pressure and shear terms of the Einstein stress-energy tensor become very large with off-axis accelerations being more energetically favourable. "Spacetime piles up in front of objects travelling at ultrarelativistic speeds". Again there is a kelvin wake or penumbral/umbral shape to the spacetime around the object, and the curvature is high enough to tear apart the object gravitationally; at relativistic speeds molecular binding energy cannot hold against the curvature of space around the object; at higher speeds still electromagnetic binding energy cannot resist the curvature; at yet higher speeds the weak force cannot resist the curvature, and so forth.

This fits well with observation and experiment here on Earth involving ultrarelativistic protons (H+) and relativistic heavier nuclei.

Anything with lots of rest mass will necessarily either be travelling at a smaller fraction of the relativistic speed limit, will have been travelling at higher fractions for much shorter durations, or will have much larger binding energy than the electroweak scale (e.g. a black hole).

Next-to-lastly, with enormous binding energy or short distances allowing for an ultrarelativistic collision, the momentum will be so high that surprisingly little energy will be transferred away from the axis of collision. Far from exploding the atmosphere, the ultrarelativistic supersoftball would pass right through the planet like a bullet (only cleaner).

Finally, there is a huge aiming problem that is being ignored: where is the Earth going to be in a few decades' time? Consider the problem from the perspective of an alien 1000 light-years away; the Earth has a minuscule angular diameter at that range, and it does not move especially cleanly because of perturbations within the Earth-Moon system, the solar system and the local group of stars. So the alien must use 1000 year old data to predict a location in 1000 years time of an object that has has several quasi periodic oscillations in its movement. Good luck!

Re:One problem

[Ihlosi]

Also, have a habitable planet ready to go is nice.

By the time a civilization is able to travel interstellar distances, whether a planet is habitable or not should be pretty much irrelevant to them.

Re:One problem

[Ihlosi]

Which would explain the Fermi Paradox - advanced civilisations exist but those that broadcast their existence are quickly stomped by others.

Err ... there's one big gaping hole in that argument: If it was true, then where's that one advanced civilization that's best at stomping out others (and at avoiding getting stomped out in return)?

Re:One problem

[Hal_Porter]

Keeping very quiet.

Re:One problem

[Ihlosi]

Keeping very quiet.

Ah, yes. I didn't think of that. Those guys have to be sneaky bastards.

Re:One problem

[Hal_Porter]

Actually it's a bit like the joke.

Q) Why do you carry that heavy idol around with you?
A) It keeps away tigers.
Q) That's ridiculous!
A) No it's not, I've never seen any tigers.

raise your hand...

[Kral_Blbec]

if you had to google chirality

Re:raise your hand...

[Anonymous Coward]

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...

[aliquis]

No, my OS got a dictionary.

Re:raise your hand...

[Anonymous Coward]

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

Re:raise your hand...

[CRCulver]

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

Re:raise your hand...

[Hatta]

Don't they cover this in the second semester of freshman chem?

Re:raise your hand...

[eclectro]

if you had to google chirality

You know, it's when you open the door for ladies.

Re:raise your hand...

[Anonymous Coward]

some of us actually read a book

Like this one? *runs*

Re:raise your hand...

[hayalci]

two hands for "life's self-assembly".

OP: not all people at slashdot are biologists, you know that right?

Re:raise your hand...

[Kral_Blbec]

In that case it died with the invention of the rotating doorway.

Re:raise your hand...

[Anonymous Coward]

What is freshman?

Re:raise your hand...

[Anonymous Coward]

Ladies? /me goes to google "ladies"?

How about earth?

[guruevi]

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?

[Psychotria]

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?

[causality]

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?

[Elgonn]

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?

[kipton]

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

Re:How about earth?

[Anonymous Coward]

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?

[Anonymous Coward]

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

Re:How about earth?

[aliquis]

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?

[treddy]

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

Re:How about earth?

[Anonymous Coward]

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?

[phantomfive]

That's what THEY want you too think.

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

Re:How about earth?

[Anonymous Coward]

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?

[Anonymous Coward]

>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?

[MaskedSlacker]

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?

[freedom_india]

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?

[sFurbo]

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?

[u38cg]

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?

[Missing_dc]

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?

[Anonymous Coward]

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

Re:How about earth?

[m50d]

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?

[masonc]

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

Re:How about earth?

[Ihlosi]

Your left or my left?

The other left, of course.

Re:How about earth?

[tibman]

[Laughs] Right, kick ass. Well, don't want to sound like a dick or nothin', but, ah... it says on your chart that you're fucked up. Ah, you talk like a fag, and your shit's all retarded. ...
Don't worry scrote! There are plenty of 'tards out there living really kick ass lives. My first wife was 'tarded. She's a pilot now.

I thought it was a hilarious movie : )

Re:How about earth?

[jtseng]

This is the basis for creating artificial sweeteners. Sucralose contains mostly dextrose, which is a mirror image of glucose. They have the same chemical formula, but since it's of the opposite chirality of all the other structures in your body it's unable to be metabolized.

Re:How about earth?

[csartanis]

From wikipedia:

The origin of this phenomenon is not clearly understood. It is even unclear if homochirality has a purpose.

So I guess its not fairly obvious. What exactly makes it obvious that a mirror image of a molecule wouldn't function exactly the same and therefore be found in the same quantity as the other?

Re:How about earth?

[mikael]

Converting food sources (proteins, molecules) from left-handedness to right-handedness and vice versa is going to take more energy than just having the same handedness as the food source. Whichever food source became dominant would eventually force everything else up the food chain to have the same handedness. In the end, everything would flip to one state or the other.

Re:How about earth?

[Ihlosi]

This is the basis for creating artificial sweeteners. Sucralose contains mostly dextrose, which is a mirror image of glucose. They have the same chemical formula, but since it's of the opposite chirality of all the other structures in your body it's unable to be metabolized.

The body can metabolize dextrose (d-glucose) just fine (in fact, it's the l-glucose that the body cannot metabolize). Sucralose, on the other hand, is a different molecule since it contains chlorine atoms in some of the places where sucrose contains HO groups. Sucralose is also about 600 times sweeter than sucrose.

Re:How about earth?

[maxwell demon]

OK, so we just have to determine the color of the main light-harvesting molecule of extraterrestrial life forms.

And hope that the planet doesn't have an advanced-enough civilization that the main light-harvesting objects on it are solar cells. :-)

Re:How about earth?

[Hatta]

Actually there are forms of DNA that twist in a right handed manner and a left handed manner. But of course that has little to do with chirality.

Re:How about earth?

[Anonymous Coward]

Chlorophyll would account for most of the chirality of Earth, but we're not necessarily looking for space-oaks here.

I mean, unless Star Trek was right, in which case we'd still probably be better off trying to determine the chirality of light reflected off a sea of fedoras, or the characteristic quantity of red light bounced off a planet full of Roman helmets.

That, and spirit gum.

Re:How about earth?

[TempeTerra]

...and that selective pressures would inevitably lead to the dominance of one particular type.

Why is that obvious? It seems obvious that left and right handed molecules should be useful for different things like the Z and S blocks in Tetris, but why should one be discarded entirely?

Re:How about earth?

[causality]

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.

While I appreciate your snide pontification and hope that it provided the feeling of correctness that you seemed to be after, you have missed my point entirely. I wasn't speaking about whether I personally have heard of this or not; you just felt free to assume that with no positive unmistakable reason for thinking so (baseless assumptions - what could possibly go wrong?). A *good* article would not have left the sort of questions open that the GP was asking. That the article doesn't begin to explain how we can detect this across interstellar distances only further reinforces my point, for that too would need to be addressed in some way before this technique could begin to be useful. It's just a poor-quality article. When someone makes a general comment about what he perceives to be the decline of journalism, do you really believe that this automatically indicates he needs your assistance with the subject matter of the article? Some people need to be needed. I don't know if that's you (see, no assumption!), but if it is, know that you won't find much joy down that path.

Re:How about earth?

[Anonymous Coward]

Bonus points to any organic chem major who can explain the difference between D,L; S,R; and (+),(-) for a chem novice like me. If there are any webpages that explain this in a helpful way (besides the oversimplified and overdetailed) with lots of examples (like a case study on glucose).... that would rock.

Also, protein folding and X-ray diffraction are interesting.... crystal handedness (left-handed DNA or right-handed DNA etc and the proteins shapes needed to operate on them) and optical chirality are different things (rotation of polarized planar light), but I haven't found good descriptions of the distinctions that aren't oversimplified or overdetailed... any bio majors want to help with that?

I'd love to be able to make my own instrument to measure chirality in solution and infer things about the chiral centers of molecules. I have laser didoes, gas lasers, polarized film, collating lens assemblies, and other things at my disposal, but I don't know where to start... any good books out there or webpages that would provide enough for a hobbyist to build an instrument but wouldn't expect me to have an organic chem lab available?

Re:How about earth?

[JebusIsLord]

The answer is that two mirror image mollecules won't necessarily fit into the same chemical receptor (think Tetris), and therefore have different biochemical effects.

Codene is actually the stereoisomer of heroin, but it doesn't fit most of our receptors so appears mostly inert.

Re:How about earth?

[osu-neko]

It's not that one set is discarded, it's just never assembled to begin with. The GP is clearly talking out his ass with the "selective pressures" thing. The fact of the matter is, most molecules used by life forms are assembled by life forms, going back to the original replicator molecules that were the progenitors of life today. When replicator molecules replicate, they make copies with the same handedness as themselves. So, if the progenitors of life on Earth were left-handed molecules, all life on Earth will be made from evolved versions of those left-handed molecules. In order for there to be both left and right handed life, life would have to had arisen at least twice, independently, and the two forms of life would be utterly unrelated to each other evolutionarily. The fact that all life on Earth is left-handed is one of the best pieces of evidence for the notion that life only arose on Earth once, and all life today is descended from that. It's possible it arose twice and both happened to be left-handed, of course...

Re:How about earth?

[IndustrialComplex]

It's possible it arose twice and both happened to be left-handed, of course...

That's interesting. I wouldn't be too surprised to find a very localized think like Archaea that could be traced to a different source. (Well I would be surprised, but I wouldn't be "That's impossible surprised")

Re:How about earth?

[furby076]

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

Sounds kinda gay to me.

Re:How about earth?

[shambalagoon]

Hmm.. does this extend to bacteria, viruses, and so on? I wonder if it wouldnt be possible to coexist with a species from an opposite-chirality world, and not fear the otherwise inevitable mutual death by deadly plagues.

Think of the movie War of the Worlds. Dropping yourself into another inhabited planet would probably be a death sentence as your body would have no resistance to the kinds of viruses and bacteria that live there. But could having opposite chirality make you immune to their effects?

Re:How about earth?

[Captain Nitpick]

Codene is actually the stereoisomer of heroin, but it doesn't fit most of our receptors so appears mostly inert.

Codeine and heroin are not stereoisomers. They have similar morphine-based structures, but not the same composition. Methylmorphine (codeine) is C18H21NO3. Diacetylmorphine (heroin) is C21H23NO5.

The more famous example is thalidomide. One isomer causes birth defects. The other is effective at countering morning sickness.

Re:How about earth?

[againjj]

This reminds me of the book "Spock Must Die!"

Spoiler warning!

In the book, a long distance transportation of Spock goes wrong (the beam is mirrored back to the ship), and a duplicate Spock is created. A lot of the book involves trying to figure out which is the "real" one in combination with solving the other issues. At one point, it is discussed that the copy was likely a mirror image. Eventually the evil one is found by noticing that he does not eat regular food, because his chirality is reversed, as the mirroring goes done to the molecular level.

Re:How about earth?

[Timothy Brownawell]

Think of the movie War of the Worlds. Dropping yourself into another inhabited planet would probably be a death sentence as your body would have no resistance to the kinds of viruses and bacteria that live there.

Probably not, actually, since there's no reason to think that you'd be a similar enough environment to whatever they usually lived in. Smallpox was bad for the native americans not just because they weren't adapted to it, but mostly because it was adapted to humans.

Of course, you could still end up dying when you find out that the atmosphere there has cyanide or hydrogen chloride or something instead of oxygen.

Re:How about earth?

[SpaceLifeForm]

No, the windows viruses are still nasty.

Re:How about earth?

[scribblej]

Correct. It pretty much has to go one way or the other; your left-handed critters like all of us cannot eat right-handed things and process them.

Re:How about earth?

[bar-agent]

Dropping yourself into another inhabited planet would probably be a death sentence as your body would have no resistance to the kinds of viruses and bacteria that live there. But could having opposite chirality make you immune to their effects?

I suppose it depends on the kind of chemical reactions involved. I don't know much about chirality, but I'm guessing the reason we can't digest those molecules is because our enzymes are the wrong shape to link up to them and rip them apart. But if an alien pathogen produced highly reactive compounds or toxic metals, or breaks cells through mechanical rather than chemical effects, we'd be affected, and our immune system would have trouble dealing with them. Can we even build antibodies for opposite chiralities?

Re:How about earth?

[bar-agent]

When replicator molecules replicate, they make copies with the same handedness as themselves.

Is this necessarily true? If a left molecule replicates to the right molecule, which in turn replicates to a left molecule again, you'd probably end up homogenous organisms that could use any available molecules, left or right.

Not any time soon...

[le_sean_moon]

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.

Quirks and Quarks Had a Good Story about This

[nz17]

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

Aliens, we are coming!

[MikeOtl67of]

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?

Re:Aliens, we are coming!

[sentientbeing]

Youd make a killing on Left-handed scissors and golf clubs

http://www.anythingleft-handed.co.uk/golf.html

Re:Aliens, we are coming!

[Dunbal]

This sound very interesting. Maybe there are business opportunities with Aliens. What do you think they would be ready to buy from us?

      Knowing us humans, we will probably be able to supply what they crave most: PORN. The interstellar DVD trade will flourish, with constant streaming of jellyfish polyps budding off, jellyfish polyps turning into medusae and for those real sickos, jellyfish catching and eating fish.

      Hey I don't ask questions, I just sell it.

Very punny :P

[Merakis]

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

Re:Very punny :P

[xactuary]

Furthermore, life is most certainly NOT even-handed.

Scanning for lifesigns

[Anonymous Coward]

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

- AC, patiently waiting for warp drives

Re:Scanning for lifesigns

[Dunbal]

One more trek concept brought to real-life, yay!

      Isn't science fun? In the meantime the religious crazies are still waiting on Jesus.... 2000+ years and counting... tick tock tick tock

Re:Scanning for lifesigns

[IndustrialComplex]

Isn't science fun? In the meantime the religious crazies are still waiting on Jesus.... 2000+ years and counting... tick tock tick tock

Hmm? We waited 4000+ years the first time.

Kids these millennia, always in such a hurry.

Re:Define "Short Distance"

[aliquis]

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.

Wow

[ShooterNeo]

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

[Anonymous Coward]

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

Re:Wow

[zeptobyte]

If only we had one of those..

Re:Wow

[rts008]

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

[Anonymous Coward]

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

Re:Wow

[sFurbo]

(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

Re:Wow

[Theaetetus]

(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

Let's see...

Freakish Array of Radio Telescopes?
Stupidly Large Ultraviolet Telescope?
Binary Interferometric Narrowband Telescope?
Coordinated Unit of Networked Telescopes?

Re:Wow

[SteeldrivingJon]

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.

Then it'd also be lost going through the source planet's atmosphere.

I don't see the scheme working.

Re:Wow

[nightstar007]

And what about then the light goes through their atmosphere?

Re:Wow

[ShooterNeo]

Intensity. By the time the light gets to us, it has an infinitesimal fraction of the intensity it started with. So any atmospheric distortion or noise would be much more significant on our end.

Re:Wow

[a-zA-Z0-9$_. !*'(),x]

I hope we don't become polarized on this.

Re:Wow

[rts008]

Yeah, that's why I did not include ludicrous, or 'it's gone PLAID!'

Re:Wow

[ShooterNeo]

Intensity. By the time the light gets to us, it has an infinitesimal fraction of the intensity it started with. So any atmospheric distortion or noise would be much more significant on our end.

Ah, life-signs!

[Anonymous Coward]

I always wondered how they were going to do that.

I'm sceptical....

[Genda]

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....

[MichaelSmith]

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....

[Sibko]

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

Re:I'm sceptical....

[MaskedSlacker]

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....

[endall]

According to this article (http://asunews.asu.edu/20080229_pizzarello), 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.

Re:I'm sceptical....

[Dunbal]

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

      Certainly not life as we know it. I can just imagine what would happen to all those algae once they manage to produce enough oxygen to - well let's say that's one world with the potential to eventually "go out with a bang". Hopefully for them any life there would use a different oxidizer...

Re:Define "Short Distance"

[RsG]

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.

Life Jim, but not as we know it!

[Omnifarious]

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 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!

[RsG]

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!

[MichaelSmith]

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!

[Anonymous Coward]

"Technical Error".

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

[TapeCutter]

"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!

[4D6963]

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!

[Omnifarious]

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. 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!

[Omnifarious]

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!

[Corporate Troll]

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.

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

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

[Anonymous Coward]

        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.

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

Life requires self-replication, it's not a definition. Just a statement of fact. Fire requires oxygen, among other things, to state the necessity of oxygen does not mean you discount other requirements.

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

[Corporate Troll]

Read the comment of the guy again: "Life requires self-replication... that's it.". That's a definition. He said that life only needs self-replication. Should have quoted the whole statement and not relying on people reading my comment alone.

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

[Anonymous Coward]

apologies, your comment was the only one I saw!

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

[Omnifarious]

I agreed with someone else who pointed this out, and I even point at the Wikipedia article. I think its 7 points are still overly restrictive, but my definition is clearly not restrictive enough.

There is mention in that article about a definition that includes not much more than the ability to evolve as being supported by some, which allows viruses and prions to be clearly labeled as being alive.

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

[Corporate Troll]

I think its 7 points are still overly restrictive, but my definition is clearly not restrictive enough.

That's okay... The 7 ones are the ones I learnt back in the day, I didn't say they were correct. I appreciate that you give in that your definition is not restrictive enough, that's bonus points for you. As far as I understand, even biologists haven't a clear-cut definition of life and diverse definitions exists, especially in the context of viruses and prions as you say yourself.

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

[Dunbal]

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.

      That "fourth spatial dimension" actually being kids in sweatshops in China and Malaysia?

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

[snowwrestler]

I think you're arguing mostly about language. A scientist, speaking scientifically, uses constrained definitions of words. "Life" in the scientific sense is only what we know on Earth, since science requires evidence and all our evidence of life is here on Earth. And everything we know to be alive on Earth does in fact require water. Thus it is a scientifically supportable statement to say that "life requires water."

That does not make it true...science is not so much concerned with "truth," but with what it can prove. It might be "true" that God exists and hides his existence perfectly. We can imagine it and it is not logically prohibited. But it is not scientifically supportable to say so at this time, since there is no repeatable evidence to support that statement. Likewise it might be true that life does not require water elsewhere in the universe. But without supporting evidence that is not a scientific statement.

If you're hung up on the word "life," consider that it might be true that gravity works differently elsewhere in the universe than it does here in the Sol system. But to speak scientifically about that, we would need evidence to support it. (I think some people believe that inflation does in fact provide that evidence.)

Many scientists have fantastic imaginations and very open minds. However when speaking scientifically they need to reign in their language and speak carefully. It's not intellectual laziness, it's discipline in communication. It does not preclude them from imagining new things to look for. It's just that until there is evidence, you can't speak scientifically about something.

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

[jameskojiro]

you're confusing it with fourth world countries.

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

[Pandrake]

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.

my brain just s'ploded...

This is all well and good, but...

[cyn1c77]

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...

[Anonymous Coward]

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

Re:This is all well and good, but...

[Anonymous Coward]

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.

Re:This is all well and good, but...

[Anonymous Coward]

Oh come one - everyone knows that the chances of anything coming from lightyears away are a million to one.

Oh, wait...

Re:This is all well and good, but...

[FreakyGreenLeaky]

The discovery of ET will be historical and mind-fuckingly exciting to the Nth degree, yet will (thankfully) quickly dissipate from the mobile vulgus mind's as their attention flickers back to The Bold And The Beautiful, Britney, Brangelina, and the shit that accumulates in their belly button.

Meanwhile, the educated will be feverishly building the biggest damn optical telescope (modular in design, mind you, so we can expand on it) in orbit to examine the planet in decent detail (like, top-view of their moist squiddy heads [complete with almost-visible brains quivering jelly-like inside a translucent veined membrane]).

Can you imagine that shit? I'd be overcome with gibbering excitement simultaneously vomiting and having an orgasm.

Re:This is all well and good, but...

[Prof.Phreak]

But if we detect they're right handed, we can at least be sure they won't eat us (or rather, won't get any nutritional value from eating us :-)

Re:This is all well and good, but...

[IndustrialComplex]

But if we detect they're right handed, we can at least be sure they won't eat us (or rather, won't get any nutritional value from eating us :-)

Until the unfortunate discovery that the source image was flipped.

Re: Oops!

[Omnifarious]

Further research shows that I'm wrong about the chirality of life on earth. Apparently left and right handed aren't used as such in biology. Amino acids, and hence proteins have L- chirality and sugars have D- chirality.

A sufficient, but not necessary condition for life

[dido]

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, 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.

Re:Define "Short Distance"

[dltaylor]

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.

Test it on Europa

[kn0tw0rk]

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

[confused one]

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

Re:Test it on Europa

[jschen]

Test it on earth first! Lots of chiral molecules on earth rotate light in one direction. Lots rotate it the other way. So the total rotation is going to be rather small. Furthermore, most molecules (including all of the atmospheric gases) are not chiral. The scientists should start by trying to detect life that's one meter away by measuring optical rotation. I doubt they'll manage. But if they do, then they can move on to longer distances.

For what it's worth, though, the scientists appear to be well aware of these challenges. In the press release, they note that they'll be starting with pond surfaces, then hopefully moving on to landscape-sized regions of earth. They're a long way from proving that this would be feasible on Europa, much less on exoplanets.

hmmm i guess we are a few lightyears away...

[Anonymous Coward]

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....

Re:I'm skeptical....

[Richard.Tao]

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

Let Me Guess...

[hyades1]

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...

[shmooattack]

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...

[Richard.Tao]

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...

[Centurix]

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.

[Ihlosi]

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

[Orlando]

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.

[shmooattack]

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.

Re:Define "Short Distance"

[Nazlfrag]

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.

Implication / equality

[Anonymous Coward]

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?

[Anonymous Coward]

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

Rather thin

[jandersen]

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...

[exp(pi*sqrt(163))]

...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.

Re:I'm skeptical....

[sFurbo]

-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....

[TeknoHog]

-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/

Re:I'm skeptical....

[Jeff DeMaagd]

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:Define "Short Distance"

[daniorerio]

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.

we search for life with lanterns

[tommten]

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

Venus and Mars are 9 light years away?

[denzacar]

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

Re:Venus and Mars are 9 light years away?

[Ihlosi]

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.

Re:Venus and Mars are 9 light years away?

[Sloppy]

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

It happened less than 9 years ago, which is also why you haven't been informed yet.

Re:Venus and Mars are 9 light years away?

[Lije Baley]

"It's because the public has a short memory...Don't you remember, a few years ago when the earth blew up, and we all escaped to this planet on the giant space ark?" - Steve Martin

PSST!

[denzacar]

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".

Re:PSST!

[Bigjeff5]

Know where I can get "the olds"? I think I'd rather have that than "the news", the news is way too unreliable.

I don't want the really old olds though, that's just history. Maybe something they've worked the bugs out of but is still relevant? Maybe all these newspapers that are failing should change their models and become recentpapers? Or maybe reliablepapers? That might help them out a bit.

Worth a shot eh?

Re:I'm skeptical....

[Cyberax]

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).

What it is

[Anonymous Coward]

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

[Richard Kirk]

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

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.

Re:Define "Short Distance"

[GreenTech11]

There was a recent discovery of a planet in what is considered the "Habitable Zone" Gliese 581. This is 20ly from Earth. Doesn't necessarily mean they can detect light off it though.

Scanning for lifeforms

[Anonymous Coward]

So you can actually "scan" for lifeforms!

Evolution and Intelligent Design are both false?

[mangu]

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

If life evolved from simpler forms then one would expect each species to inherit the handedness of its ancestors, all the way to the very first living being.

OTOH, if life was designed by a creator, then one would expect that creator to have some preference for one handedness over the other.

Correction to Article Summary *

[Dr. Hugh Everett III]

Article summary is incorrectly attributed to "Scientists working at [NIST]." Out of the 12 authors of the report, only a single author [Gerber, author no. 4] is affiliated with NIST, which issued the press release. The first author of the report is William Sparks, who is based at the Space Telescope Science Institute in Baltimore (3 authors). The remaining authors are based at

* Center for Astrophysics Research (University of Hertfordshire) (2 authors),
* Department of Astronomy (University of Maryland),
* Center of Marine Biotechnology (University of Maryland Biotechnology Institute) (4 authors),
* Canada-France-Hawaii Telescope.

Maybe on Nasa/Esa Darwin project?

[Herve5]

I requested the full paper but... as we are friday afternoon here in Europe I'll probably get it on Monday ;-)
In the meanwhile, from the abstract I feel this'll be more applicable to say checking remotely life hints in Jupiter's atmosphere here, than getting answers for remote stars tomorrow.

I for one highly doubt, for instance, that just analysing an exoplanet's transit onto its star will bring any measurable polarization.
Just remember what you see is star light that passed through the planet's *atmosphere*, not reflected onto its ground (and grass/trees).
And as this specific light is moreover buried within the 99,99% of starlight that just didn't cross the planet at all, even with a specifically intense *atmospheric* life (a dense, GREEN atmosphere ;-) it'll be very difficult to detect the ppm of added polarization.

Rather, I see this either for

a) a futuristic payload for the (too futuristic) Darwin project from Esa/Nasa ( http://www.esa.int/esaSC/120382_index_0_m.html/ ), when the dozen of years of development (and equal number of euro and dollar billions) will have been invested: if things go well, no more crises, etc., we then will have a way to just switch the starlight off (via destructive interferometry), and see only planet's light.
Then maybe you'll measure polarization. But then you'll also measure specific wavelength absorptions, so get directly to molecules (which is the raison d'être of the Darwin project)

b) as said earlier, maybe in nearer times a way to observe our neighboring planets atmospheres, and suddenly discover they may be polarized (or not, and that check will be quick).
If they were it'd definitely be fun.

In my space factory there is a breadboard of the Darwin nulling interferometric concept. Nifty. Representing maybe 1% of the required development work. But nifty, definitely: capable of switchig off a star light that is millions of times superior to the planet's reflected light and at the same time leave planet's light in, when planet is just the pixel against the star's one. As they say on Esa's site, capable of seeing a candle light stuck against a lighthouse firewindow, from 1000 km away.

Re:A sufficient, but not necessary condition for l

[Anonymous Coward]

From what's on that page, it is mentioned that archaea use left and right phospholipids, unlike other organisms, and this implies the use of protein enzymes that are again quite different from other organisms in order to work with them. That is very cool, but it doesn't say there are left and right-handed proteins (as in using both left and right-handed amino acids to assemble them). If you do have a source that says that, I would be really interested.

Verified random chirality in non-living?

[Anonymous Coward]

While they have done some experiments to show that living things on Earth have the same handedness because we evolved from a common ancestor I wonder if they have tried non-living things to see if there might be some heavy chirality there as well.

For instance what if there is some naturally occurring, symmetric phenomenon that caused clustering of handedness, e.g. the rights sink while the lefts float.

Or what if you have a world that has life from many different places like that bar in Star Wars.

Sound like a good start though.

Re:Evolution and Intelligent Design are both false

[telchine]

if life was designed by a creator, then one would expect that creator to have some preference for one handedness over the other.

But the Flying Spaghetti Monster doesn't have hands, just noodley appendages! I doubt he has any preference for hands!

Handedness

[rossdee]

If we discover life that is of opposite handedness to the life on this planet, then they wouldn't be able to eat us.
On the other hand we wouldn't be able to eat them :(
but on the gripping hand thry could still hunt us for sport. (or we could hunt them for sport.)

Danger, Will Robinson?!

[memorycardfull]

If this method for detecting life works well then you better believe any advanced alien civilization relatively close to us probably already knows exactly where we are. Perhaps we should hope that life is so common in the universe that they are working their way down a long boring list of warm wet rocks with weird crap growing on them and it will take them a long time to investigate us.

Handing Out Assumptions

[DynaSoar]

"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."

He's not talking about life, he's talking about Earth life. We have only one data point to go by, which is too little to draw generalities from.

It is perfectly plausible that a biosphere could be bichiral. There could be parallel but non- or weakly-interacting ecosystems, or one ecosystem with organisms that exhibit both. False negative.

There could also be monochiral planetary surfaces due to the process of catalysis of organic but non-biological compounds. False positive.

It doesn't make sense to me to look for extraterrestrial life by looking only for the characteristics of terrestrial life, any more than we should look for extraterrestrial civilizations to be comprised of humanoids or even humans. "The problem with aliens is, they're alien." (Greg Benford? Larry Niven?)

Re:Define "Short Distance"

[sam_handelman]

Parent is abrasive, but I think his point is probably correct.

  I'm not an astronomer - but I'm a biologist and we do circular dichroism measurements on biological samples (wikipedia article is good enough: http://en.wikipedia.org/wiki/Circular_Dichromism).

  The notion that you could detect these signals from an exoplanet lightyears away - given that we can't, at the moment, detect light from such planets at all - strikes me as somewhere between far fetched and complete bullshit.

  On the other hand, as a device on a mars rover (or even a satellite probe, maybe, although I doubt this would work through the atmosphere) this makes a lot of sense. So tag this as xenobiology rather than astronomy and we're maybe okay. Can't say more without reading the actual paper.

The joke is on you astronomers! says the Zorrans

[140Mandak262Jamuna]

The planet Zorran, neighbor of Tattoonie, has an interesting biology. The left handed chirals evolved into the plants and the right handed Zorrans evolved into animals. How do the animals digest the plant matter you ask? Well their mitochondria is actually ambi-chiral called mitachloreans. Thus the light reflected by Zorrans has both left and right handed chiral-photons.

What About Just Asking Them?

[Anonymous Coward]

The Andromedans for example.

military use

[Anonymous Coward]

I bet the military will use it first.
With all the robots and gears they use during conflicts, don't you think they badly want to know what is alive?

Re: Oops!

[Anonymous Coward]

In Latin, "left" and "right" are "laevus" and "dexter", hence the L and D for left and right handedness.

But does self-assembly mean life?

[tgibbs]

I agree that chirality implies some kind of autocatalytic process to amplify weak natural chiral bias or statistical fluctuations, but I don't agree that it is diagnostic for life. After all, crystals self-assemble, so a planet dominated by large crystal structures could be highly chiral.

Self-assembly is only part of the definition of life--there also needs to be mutation, and the mutation has to affect the propagation of subsequent generations.

Re:Evolution and Intelligent Design are both false

[IndustrialComplex]

OTOH, if life was designed by a creator, then one would expect that creator to have some preference for one handedness over the other.

Why would you expect that?

Light fingered aliens

[aynoknman]

I've been aware of light fingered aliens for a long time. I have half a drawer of unmatched socks that constitutes proof of their existence.

Re: Oops!

[saforrest]

In Latin, "left" and "right" are "laevus" and "dexter", hence the L and D for left and right handedness.

I think [s]he knew what the L and D stood for... the comment "I was wrong" referred to the statement that "Biological processes on earth tend to produce almost exclusively right handed molecules."

Re:Evolution and Intelligent Design are both false

[osu-neko]

So, this would be evidence against the notion that life was created by the FSM. Perhaps the "research" is part of a plot by evil pirates. Or would that be evil ninjas?

Re:Define "Short Distance"

[osu-neko]

Right. In fact, it's an interesting system. There's a planet in it that we have seen by the light reflected off of it, but that planet is not in the habitable zone. There's also a planet in the habitable zone, but we detected that one by more indirect means. So, close, but no banana...

We're getting close, though, to getting all those parameters to line up. So it's nice that we have this new test ready for when we finally find a good candidate to use it on.

Re:Define "Short Distance"

[osu-neko]

The notion that you could detect these signals from an exoplanet lightyears away - given that we can't, at the moment, detect light from such planets at all - strikes me as somewhere between far fetched and complete bullshit.

This would be where you're "I'm not an astronomer" is showing. In fact, we can and have detected light from exoplanets. We've even done spectral analysis on some of them to discover their atmospheric composition. So, there's nothing at all far fetched about this.

Re:Evolution and Intelligent Design are both false

[Timothy Brownawell]

OTOH, if life was designed by a creator, then one would expect that creator to have some preference for one handedness over the other.

Why would you expect that?

Compatibility?

Detecting Lifeforms

[Alan R Light]

I had always wondered how they detected lifeforms - even one or two lifeforms on an otherwise desolate planet - in Star Trek, Star Wars, and the like.

Now I know.

Incidentally, I'm right handed.

Re:Evolution and Intelligent Design are both false

[Bigjeff5]

Well, if you're building a system with base organisms that are food for higher level organisms, which are food for even higher level organisms, etc. then having the wrong handedness means you cannot participate in the chain.

How does a left handed cow eat right handed grass? Furthermore, how would a right handed tiger eat a left handed cow?

They try to use it as evidence against a creator and for evolution, but that doesn't make much sense, since a creator would have to build two separate and completely incompatible eco-systems. It makes more sense to make just one that is fully inter-dependant and self-supporting.

Actually killer evidence against a creative entity would be if it were found that we did have more than one biological system on the planet - one right handed and one left handed. They would eventually merge into the two regardless, and in truth one would probably eventually eliminate the other, but there is no reason evolution shouldn't initiate more than one system. In fact, it should have initiated millions of them, which eventually "stuck" and were able to flourish. This would almost guarantee two systems, at least in the beginning.

Anyways, those are just my thoughts. The handedness of molecules is new to me.

Re:A sufficient, but not necessary condition for l

[dido]

You're right. On a closer reading, it seems that the article doesn't quite say that archaea need to have used enzymes made up of right-handed proteins in order to generate the right-handed glycerol groups which make up part of their cell walls. Then again, the biology of archaea is still poorly understood. Nevertheless, their use of such a right-handed organic molecule in their cell membranes, where everywhere else in life on earth similar molecules are left-handed, is one example of the case I describe. If we had a planet where the dominant life forms were archaea (right-handed glycerol groups in cell walls) and bacteria (left-handed glycerol groups) in more or less equal numbers, might not the detection method fail to find any chirality bias in the light from the planet? This may have been case in the young earth when life first began to evolve.

Note to self:

[JoCat]

When greeting aliens, shake with left hand.

But seriously, it's an exceptionally interesting thought that there might be a 'biological life scanner' like the kind seen in Star Trek, WALL-E, and other science fiction of the sort.