Discussion and news about the modern effort to understand the nature of life on Earth, finding planets around other stars, and the search for life elsewhere in the universe

Monday, November 29, 2010

The ten most important questions for astrobiology: Number 3

It would be easy to argue that the next question is too big, to broad, and too unanswerable to be in the list. Nonetheless it's a question that keeps cropping up and is also representative of the bigger and deeper issues that astrobiology must ultimately tackle. So, question number 3:

Is this universe particularly suited for the phenomenon of life?

Because this is a bit ambiguous there are some necessary qualifications. First, implicit in the way I've phrased this question is the idea that 'this universe' is either one of many or that it represents an instance of a phenomenon that somehow reoccurs. Second, and this is really just an expansion of the question, it suggests that life requires a particular range of physical laws and/or 'contents' in a universe to happen. Third, this question hits the button to sound the anthropic principle klaxon, opening a Pandora's box of weak and strong arguments about the timing of life, its privileged position and even its necessity for the existence of the universe in the first place.

It can be quite a morass, so I'll try to stick to the easy bits. The second item above can also be rephrased as a question about what the minimum requirements are for life to show up at some point, and whether some physical laws are more or less important. If we stick with carbon-based life then there's a ready laundry list, not least of which is the need for carbon in the first place. Carbon comes from the triple-alpha process in stellar nucleosynthesis. Intriguingly this set of nuclear reactions hinges critically on resonances between nuclear energy levels, allowing beryllium and helium nuclei to gracefully flop into forming a new carbon-12 nuclei. Without that coincidence then carbon would be little abundant in the universe, rather than the 4th most abundant element in the universe - after hydrogen, helium and oxygen. This resonance hinges in turn on the value of the fine-structure constant, describing the universal strength of electromagnetic interaction. Change this constant by a few percent and among the consequences you can kiss carbon goodbye.

Even if you feel you can do without carbon - preferring some alternative life chemistry - then a different fine structure constant also messes up things like covalent bonds in molecules, at least compared to the way they are around us. Before even getting to details like this if the universe had a different overall composition, or differing gravitational constant, or differing CP violation, then it could be radically different from the outset - perhaps never making any structures beyond individual atoms. In brief, there are a lot of things that seem to have to fall into place for something like us to come along.

Because we feel (rightly) incredibly uncomfortable with any notion we might be special to the universe (the universe clearly being special to us) then things get sticky, and answering question 3 hits a wall....unless we get to the first qualification I give above: the universe is one of many, whether contemporaneous (multiverses) or one of an endless succession (cyclical). An infinite number of universes, or quantum realities, are like the infinite number of monkeys with typewriters - somewhere amongst them will be the ones that can produce life like us. Much like the realization that carbon production requires something special - and indeed how Fred Hoyle came up with the physics for it - it may be that a version of the anthropic principle is actually telling us that there must be multiple universes, or else things are even more bizarre.

Astrobiology can't answer 3 yet, at least not in any satisfactory way. But finding out more about life in the universe, carbon-based or otherwise, could just possibly nudge us in the right direction.


island said...

Because we feel (rightly) incredibly uncomfortable with any notion we might be special to the universe (the universe clearly being special to us) then things get sticky, and answering question 3 hits a wall...

More like... 'Because we feel uncomfortable with any notion we might be special to the universe... scientists become willfully ignorant of this plausibility, (as was pointed out by Brandon Carter), and 3 hits ideological dogma like it was a brick wall.'

And that is why we have no solution to the fine tuning problem from first principles... and is the reason that we will never have a complete theory of quantum gravity, much less, a final theory of everything...

Caleb Scharf said...


To be devil's advocate - if the universe turns out to be full of wildly varying forms of "life", with different types of consciousness etc etc. doesn't that rather thwart some of the anthropic arguments that hinge on the nature of life here on Earth? Of course maybe that isn't the case, or maybe they could be incorporated into some kind of meta-anthropic principle.

island said...

I would argue that the goldilocks "enigma", (as Paul Davies calls it), makes extremely specific and falsifiable predictions about exactly where life will and will not be found elsewhere in the observable universe, and what form that they will take.

I would also argue that it is this "balanced" commonality that our ecobalances share with the "flat" balanced universe itself, which is most apparently indicating that we share a direct connection with the mechanism that defines the life-oriented structure principle that I have been alluding to.

And again, dogma is all that stands in the way...

island said...

FYI: I don't think that even Davies realizes that THIS is the trick to the predictive capabilities of the physics, and it includes Dicke's observation, which means that ALL life evolved at approximately the same time in the history of the universe, and voila, a clear explanation for the Fermi Paradox, as well.



Rainbow said...

The so-called "Goldilocks Enigma" is a misguided one. If we change not one, but two or three parameters, we could still come up with a viable Universe. IMHO, This question belongs more to Cosmology than to Astrobiology

island said...

What is a "viable universe"?

If you mean one that includes life, I doubt that lame assertion that you hear anybody and everyone who doesn't like the anthropic principle and wants to pretend like there's nothing to it, claim... IMHO... ;)

Rainbow said...

Well, really, what we DO know about life's average abundance and probability in our Universe or all Universes? I think we need to know something more before we judge OUR kind of life the only kind of life possible. I think the Anthropic Principle to be a tautology of the most Lapalissian kind: we can live in this Universe, therefore this Universe is fit for us. Hey, this is reasoning, boys. Then someone goes on to "think": we don't know of any other life, or any other universe, therefore no other Universe of Life is possible.
Well, really!

Rainbow said...

I didn't say it doesnt belong to astrobiology: but if we want to analyze life, better begin to life in OUR Universe. There's a lot to explore before we think of life in Unverses different from ours. I think life to be the result of Universes' evolution, as Lee Smolin expounded in The Living Universe. Did you read it?

island said...

Me?... I, personally, think that I have very good reason to believe carbon based life is a specially relevant and purely necessary function of the thermodynamic process that was destined to arise over the specifically defined region of the observed universe, and at an equally specific time in its history... from the moment that the matter field got laid down by the big bang.


I also think it requires willful ignorance of the evidenced plausibility for a bio-oriented cosmological structure principle to assume that the "precariously balanced" commonality that our own local ecobalances share *uncommonly* with the "flat" balanced structure of the universe itself isn't begging the obvious cosmological question.

And I think that it's a crying shame that this is the mentality of the manstream, as well, considering that they have tried and failed miserably for the last thirty to fifty years to resolve this problem from the first physics principles that are expected to explain the otherwise totally unexpected configuration that is observed.