If we really want to find life on other worlds, why do we keep looking for life based on carbon and water? Why don’t we look for the stuff that’s really different?
In the immortal words of Arthur C. Clarke, “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”
I’m seeking venture capital for a Universal buffet chain, and I wondering if I need to include whatever the tentacle equivalent of forks is on my operating budget. If there isn’t any life, I’m going to need to stop watching so much science fiction and get on with helping humanity colonize space.
Currently, astrobiologists are hard at work searching for life, trying to answer this question. The SETI Institute is scanning radio signals from space, hoping to catch a message. Since humans use radio waves, maybe aliens will too. NASA is using the Curiosity Rover to search for evidence that liquid water existed on the surface of Mars long enough for life to get going. The general rule is if we find liquid water on Earth, we find life. Astronomers are preparing to study the atmospheres of extrasolar planets, looking for gasses that match what we have here on Earth.
Isn’t this just intellectually lazy? Do our scientists lack imagination? Aren’t they all supposed to watch Star Trek How do we know that life is going to look anything like the life we have on Earth? Oh, the hubris!
Who’s to say aliens will bother to communicate with radio waves, and will transcend this quaint transmission system and use beams of neutrinos instead. Or physics we haven’t even discovered yet? Perhaps they talk using microwaves and you can tell what the aliens are saying by how your face gets warmed up. And how do we know that life needs to depend on water and carbon? Why not silicon-based lifeforms, or beings which are pure energy? What about aliens that breathe pure molten boron and excrete seahorse dreams? Why don’t these scientists expand their search to include life as we don’t know it? Why are they so closed-minded?
Credits: NASA/Jet Propulsion Laboratory, Caltech
The reality is they’re just being careful. A question this important requires good evidence. Consider the search for life on Mars. Back in the 1970s, the Viking Lander carried an experiment that would expose Martian soil to water and nutrients, and then try to detect out-gassing from microbes. The result of the experiment was inconclusive, and scientists still argue over the results today. If you’re going to answer a question like this, you want to be conclusive. Also, getting to Mars is pretty challenging to begin with. You probably don’t want to “half-axe” your science.
The current search for life is incremental and exhaustive. NASA’s Spirit and Opportunity searched for evidence that liquid water once existed on the surface of Mars. They found evidence of ancient water many times, in different locations. The fact that water once existed on the surface of Mars is established. Curiosity has extended this line of research, looking for evidence that water existed on the surface of Mars for long periods of time. Long enough that life could have thrived. Once again, the rover has turned up the evidence that scientists were hoping to see. Mars was once hospitable for life, for long periods of time. The next batch of missions will actually search for life, both on the surface of Mars and bringing back samples to Earth so we can study them here.
The search for life is slow and laborious because that’s how science works. You start with the assumption that since water is necessary for life on Earth, it makes sense to just check other water in the Solar System. It’s the low hanging fruit, then once you’ve exhausted all the easy options, you get really creative.
Scientists have gotten really creative about how and where they could search for life. Astrobiologists have considered other liquids that could be conducive for life. Instead of water, it’s possible that alternative forms of life could use liquid methane or ammonia as a solvent for its biological processes. In fact, this environment exists on the surface of Titan. But even if we did send a rover to Titan, how would we even know what to look for?
We understand how life works here, so we know what kinds of evidence to pursue. But kind of what evidence would be required to convince you there’s life as you don’t understand it? Really compelling evidence.
Go ahead and propose some alternative forms of life and how you think we’d go searching for it in the comments.
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Carbon and water do the job really well. If life is plentiful in the universe, it’s hard to imagine that carbon/water based life not being ubiquitous, even if other chemistries are also possible.
The whole truth and NOTHING but the truth about “another kind of life” is that Yes, It exisists. It’s there. It’s here within our own magnetic field. Man has been able to learn the science that can help him appreciate the material Universe. And to a lesser degree, man has been endowed to understand but not be able to fully explain the logistics of how “a different kind of life” is (in reality) all around us. THAT specific science is not for us to know, not just yet. However, suffice it to say that the unknown “Other Life” is evidenced by what has been given the name of “PARANORMAL.” Want to believe it or not? That’s a personal choice.
I just don’t have the knowledge, intelligence, imagination to “Go ahead and propose some alternative forms of life and how you think we’d go searching for it in the comments.” But I’d rather not wait until a creature hits us over the head, so to speak. Maybe, if I can believe in God, I can believe in the unknown, un-understandable, un-provable.
Thanks for leading us in thought/discussion on this subject.
Believing in some kind of God… any God is just a sign that that person does not understand the whole thing… just some bits n pieces, but vital parts are (still) missing. So, depending on the state of education, to make that thing work it adds some kind of or, if that person has some insight in science, a :-).
And before you start to attack me: I’m glad that there is no such thing as a Paradise! Imagine you have to spend eternity with these bible / torah / koran folks ..! No thanks!
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So, depending on the state of education, to make that thing work it adds some kind of GOD or, if that person has some insight in science, a COSMOLOGICAL CONSTANT (Greek capital letter lambda) :-).
@TedH, Art Linkletter once observed, (quote) “People Are Funny.” Trying to inject humor into a world repleat with various cultures & religions can help lower tensions. But it will only go so far. When it comes to belief in the divine, ignorance pops out its head and takes over reason and logic. The Greatest Man That Ever Lived once told his listeners that, due to personal religious beliefs, Fathers would kill sons, Mothers would turn on their daughters, Sister against Brother and so on. It turned out to be so. Those putting their faith in a Torah, a Koran, a Bible and other assorted guides share one imbedded attribute- Spirituality. Thus the need for “Something Out There.” That same Great Man also stated that “By their fruits you shall know them.” When Christiandom, Paganism, Islam (and all the others) have only produced hatred, boundaries, walls, 72virigins just awaitin’, decapitations, world wars, poverty, local wars, greed and all the other “Fruit” we see daily- well then TedH, it’s no surprize you state, “And before you start to attack me: I’m glad that there is no such thing as a Paradise! Imagine you have to spend eternity with these bible / torah / koran folks ..! No thanks!
Well said Janet….
We need to know exactly what life is. We need to know how and where it originated. We know none of these things. So, at this point? Well, first I’d be sure and pack a good microscope and rock hammer when heading elsewhere in the solar system. After arriving, I would use that microscope and the naked eye of course, to look for anything that moves, and anything that looks like it used to move. I’d look for anything that looks like it was moved by anything that moves or used to move. I’d look for anything that is growing or anything that looks like it used to grow. We don’t know what life is, but we do know that life manifests itself as matter that is behaving in an unusual way. Thus it stands to reason that ‘alien’ life that uses a different metabolic process would still be recognisable in one of the forms above.
If I find something elsewhere in the solar system, I will remember to not be surprised when molecular analysis reveals it is or was related to life found on Earth.
What mewo said.
Other forms of life might exist but they will be extremely rare.
Our life form is made of all the very common elements.
Also realize that these other life forms might never progress beyond single cells or evolve very slowly.
For animal life you really need a reactive gas like oxygen in the atmosphere. And you need them to be outside of an ocean.
An alternative life form might exist on titan and that is worth exploring, But its likely to have a very slow metabolic rate. What might take 4 billion years of evolution on Earth might take 100’s or 1000’s of times longer at 94 Kelvin.
Why should it be “extremly rare”?
Why does “animal life need to be out of an ocean”? What kind of species are fish… whales… lobster..?
Yes, it is hard to be very specific on how to go on searching for truly alien life. However, we can start from simple, plausible assumptions: fundamental Physics encourages forming of ever more complex systems wherever, however it is locally possible (entropy must rise and do so through maximum number of microstates, find your fav’ textbook form of this Quantum Mechanic principle). Hence, on long term life as self-organized complexity must arise wherever, however it is locally possible. By definition this process has nothing to do exclusively with carbon and water. Any complex Chemistry has potential to yield life based on it, if conditions for it succeeding locally are good. Hence, we must expect life in many forms, that must be our scientific expectation. Nothing in Physics limits complexity to carbon and water.
That said, how to proceed? – Nature have developed us with innate capabilities to proceed – we are excellent “machines” for detecting anomalies and patterns. Some of the best Science discoveries happened that way – we saw anomaly and than explained it. Life by definition interacts with surroundings and changes it. We must look for inevitable anomalies in environment from this process and be ready to attempt to explain them with life complexity suitable for that environment in mind. Say, in the easiest case of Titan – plenty of work have been done on the potential of methane based metabolism, even the expected size of the organism functioning like that. Even easier than looking for any and all anomalies, on Titan we can look for specific, predicted ones. Further, same as done for Titan, we must think about potential complex chemistry for other unusual places, not ignore them – Pluto, Io,… even Venus. Once we start solving those puzzles we are on the correct path, off the carbon training wheels.
As for signaling-based SETI, we must stop projecting human concepts to fundamentally alien life. If there is alien intelligence (and Physics hints that there must be and plenty of it) out there – again, only search for observed anomalies would do. We may radio-listen but not for “messages”, instead for WOW! signal like anomalies and than dig deeper if we find any.
It’s harder to know *what* to look for…
What if we eventually find, as other species have found(?) that indeed the speed of light IS the speed limit in our space/time and that nothing can travel faster. This means making the crossing to even the very nearest stars would take an extremely long if not absurd amount of time. On the flip side perhaps it is an instantaneous journey done without a physical body? Got angels?
So far, we have thought of ‘life’ as spontaneously-evolved life. Carbon seems to be about the only element that can link to itself in enough different ways to preserve the complexity. There may be ways of getting by with less water.
However, suppose we are looking for some designed life-form. This might not reproduce as we do, but manufacture itself from parts. If it is going to travel through space, it will probably want some very permanent memory to survive the radiation and the long wait between stars, plus a low mass to go fast and survive acceleration and deceleration, and the ability to make the bits it didn’t need for the trip from the materials it finds. That’s not much like life as we know it.
It’s going to be carbon again, isn’t it?
If we are interested in evolved life, able to communicate with other interstellar species, I’d first look around stars which:
– are at least as old as the Sun to allow the evolution of a technological species
– have another star relatively nearby (say within 50 lightyears) which is a supernova candidate
Such species would be looking for means to travel or at least communicate away from the supernova candidate in order to save some of their specimen or at least their knowledge.