Sun's properties not 'fine-tuned' for life
22 May 2008
New Scientist
There's nothing special about the Sun that makes it more likely than other stars to host life, a new study shows. The finding adds weight to the idea that alien life should be common throughout the universe. "The Sun's properties are consistent with it being pulled out at random from the bag of all stars," says Charles Lineweaver from the Australian National University (ANU) in
Some previous studies of the Sun's vital statistics have concluded that it is unusual among stars, for instance, by having a higher mass than average. Such atypical properties might somehow help explain why the Sun seems to be unique, as far as we know, in having an inhabited planet. But the earlier studies only looked at a small number of solar features, such as its mass and iron content. Lineweaver suspects there was a temptation to sift through the Sun's properties, then focus on the outstanding ones while ignoring the normal ones.
"You can mistakenly come to the conclusion that the Sun is 'special'," Lineweaver told New Scientist. With his ANU colleague José Robles and others, Lineweaver has now analysed 11 features of the Sun that might affect its ability to have habitable planets.
They included its mass, age, rotation speed and orbital distance from the centre of the Milky Way. Then they compared these with well-measured statistics for other stars to answer the question – overall, does the Sun stand out from the crowd any more than some other randomly chosen star would? The Sun did stand out in two ways: it is more massive than 95% of nearby stars and its orbit around the centre of our galaxy is more circular than those of 93% of nearby stars.
But when all 11 properties were taken on board, the Sun looked very ordinary. Robles's team calculates that there would be only about one chance in three that a star selected at random would be "more typical" than the Sun. They conclude that there are probably no special attributes that a star requires to have a habitable planet, other than the obvious one – the planet must be within the star's habitable "goldilocks" zone, orbiting at a distance where the temperature is not too hot for life, nor too cold, but just right.
[Interesting….]
8 comments:
Somehow this doesn't sound like news to me. It seems that way back when I was studying astronomy it was generally thought that the Sun was very ordinary. I'd be curious to know what other 'studies' had been done that had found the Sun to be 'special'. Even the conclusion that the Sun is larger than most nearby stars depends an awful lot on what is considered 'nearby'. Most of the stars that we can see are quite a lot larger than our Sun. As stars go, ours is definitely not large, which does probably help promote life, as it is much more stable over a long lifetime than a larger star.
I think I'll have to go read the original report.
But that means WE'RE not special!!! {cries}
That's what I think is truly behind all the religion stuff. In addition to explaining things they couldn't understand, people just needed to feel special. So they created Gods that created them for a special purpose. Human self-consciousness is a bitch sometimes, eh?
But that "obvious one" is a real doozy! There's a whole lot more involved than temperature as Lineweaver himself knows as well and anybody given that he's a leading researcher in the area of the Galactic Habitable Zone (GHZ) or "goldilocks" zone.
Charles H. Lineweaver, Yeshe Fenner and Brad K. Gibson, “The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way,” Science 303 (2003), 59-62.
He may not see too much special about the sun, but that doesn't mean he thinks there is nothing special about the Earth or about the very narrow range of parameters associated with the GHZ. Other researchers have discovered additional parameters of the GHZ that further restrict the possibilities of life in the universe. And those make up just one set of parameters. There are hundreds of other sets. When you start putting them all together, even just a few of them, it starts to look like like a rigged game.
In the words of the atheist astronomer Fred Hoyle:
"Would you not say to yourself, "Some super-calculating intellect must have designed the properties of the carbon atom, otherwise the chance of my finding such an atom through the blind forces of nature would be utterly minuscule." Of course you would . . . A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature. The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question."
One doesn't have to look at the world through the lens of religious zealotry in order to see the "specialness" of life on Earth.
Jeffy said: It seems that way back when I was studying astronomy it was generally thought that the Sun was very ordinary.
That was my impression too, both from what I read & what I was told in school.
Jeffy said: I'd be curious to know what other 'studies' had been done that had found the Sun to be 'special'.
I'll see if I can dig something up for you.
Jeffy said: As stars go, ours is definitely not large, which does probably help promote life, as it is much more stable over a long lifetime than a larger star.
That's my understanding too. Large stars tend to burn out quicker. Quicker, of course, being a relative word...
Laura said: In addition to explaining things they couldn't understand, people just needed to feel special. So they created Gods that created them for a special purpose.
Totally agree. How can the universe *not* be special with ME in it? Sad really how people have such a bloated feeling of self importance. Along with the fear of death it goes a fair way to explain quite a lot of religion.
LB said: he's a leading researcher in the area of the Galactic Habitable Zone (GHZ) or "goldilocks" zone.
The *Galactic* habitable zone.... You mean that parts of the *Galaxy* are more habitable than others? I guess that its pretty rough near the core but... how exactly big *is* this zone - presuming that we're in it....
LB said: Other researchers have discovered additional parameters of the GHZ that further restrict the possibilities of life in the universe. And those make up just one set of parameters. There are hundreds of other sets. When you start putting them all together, even just a few of them, it starts to look like like a rigged game.
It's very difficult to generalise from a single example - us - to the rest of the Universe. Saying that life can't exist there or there or over there is easy to do. However, I shall hold off judgment until we know more about other planets & the emergence of life.
Earth *is* special in the sense that it's the only planet we know of with life. But we still don't know exactly how life started here and we don't know exactly the conditions under which it did start. Dismissing other planets as unsuitable for life is fraught with problems.
LB said: In the words of the atheist astronomer Fred Hoyle...
[laughs] I like the way you labeled him as an 'atheist' astronomer...
LB quoted: "The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question".
Ah, the laughable 'Anthropic Principle' I presume?
Look at it this way: Two fish in the middle of the Pacific Ocean are discussing philosophy... One remarks at how amazing it is that the Ocean provides them with everything they need and seems to be designed just for them. The number of things that are 'just right' for fish-life *cannot* be coincidental: Therefore the Ocean *must* have been designed FOR them by a Higher Intelligence. I mean - just what is the alternative?
What they fail to realize, of course, is rather than the Ocean being *designed* for them is that over millions of years they have *adapted* to it. In the same way that the Universe is *not* designed for us. We have adapted to it. If the Universal Constants were much different then stars would not have formed and the Universe would just be a huge sheet of Hydrogen... and we wouldn't be having this conversation. That does *not* mean that there is *any* evidence of design.
You mean that parts of the *Galaxy* are more habitable than others? I guess that its pretty rough near the core but... how exactly big *is* this zone - presuming that we're in it....
It's more proper to say parts (or at least one part) of the galaxy can support life and other parts can't. The GHZ is well-documented on the web and it would take a great deal of time and energy to explain it, but if you are looking for answers I'm sure you can find them. For starters the GHZ is determined in large part by factors other than distance from the sun, which (probably because even a 5-year-old could understand it) is the only one mentioned in the article.
I labeled him as an atheist because 1) he was, and 2) my point was that even among those with a bias against God and religion, the facts seem to suggest something fishy. Otherwise his quote would have been dismissed as the ramblings of a jesus freak. As it is, it's dismissed because you don't agree with it.
As for the “laughable” anthropic principle, it seems you believe the term was coined recently by religious apologists. In reality the principle was first developed in 1961 by Princeton physicist Robert Dicke in an article titled “Dirac’s Cosmology and Mach’s Principle” published in Nature 192. The first published scientific paper using the phrase was written by British mathematician Brandon Carter titled “Large Number of Coincidences and the Anthropic Principle in Cosmology,” in the Proceedings of the International Astronomical Union Symposium, No. 63: Confrontation of Cosmological Theories with Observable Data in 1974.
[Here is one such coincidence drawn from the observable data: the odds of getting a single given protein half right given every particle in the universe attempting it at the maximum possible rate (thousands of times per second) for 15 billion years: 7.4x10-165]
In 1986 when John Barrow and Frank Tipler published The Anthropic Cosmological Principle the phrase was made popular.
Two quotes representative of the opinion of much of the scientific community:
“With regard to the appearance of a single molecule of the cytochrome c family, one needs 1036 ‘acceptable planets’ with just the right conditions for 109 years... One who finds the chance appearance of cytochrome c a credible event must have the faith of Job....”
- H.P. Yockey, "A Calculation of the Probability of Spontaneous Biogenesis by Information Theory," Journal of Theoretical Biology (1977) 67, pp.393
“The origin of life appears to be almost a miracle, so many are the conditions which would have had to be satisfied to get it going.”
- Sir Francis Crick, Scientific American, February, 1991
So if this "laughable" you are laughing at the work and opinion of some the this century's most notable scientists.
On the other hand we must give due consideration to Cyberkitten and his two fictional, philosophizing fish. So let’s consider it with another bit of fiction from Richard Swinburne's ‘The Argument from Design’.
Suppose that a madman kidnaps a victim and shuts him in a room with a card-shuffling machine. The machine shuffles ten decks of cards simultaneously and then draws a card from each deck and exhibits simultaneously the ten cards. The kidnapper tells the victim that he will shortly set the machine to work and it will exhibit its first draw, but that unless the draw consists of an ace of hearts from each deck, the machine will simultaneously set off an explosion which will kill the victim, in consequence of which he will not see which cards the machine drew. The machine is then set to work, and to the amazement and relief of the victim the machine exhibits an ace of hearts drawn from each deck. The victim thinks that this extraordinary fact needs an explanation in terms of the machine having been rigged in some way. But the kidnapper, who now reappears, casts doubt on this suggestion. ‘It is hardly surprising’, he says, ‘that the machine draws only aces of hearts. You could not possibly see anything else. For you would not be here to see anything at all, if any other cards had been drawn.’ But of course the victim is right and the kidnapper is wrong… The fact that this peculiar order is a necessary condition of the draw being perceived at all makes what is perceived no less extraordinary and in need of explanation. The teleologist’s starting-point is not that we perceive order rather than disorder, but that order rather than disorder is there. Maybe only if order is there can we know what is there, but that makes what is there no less extraordinary and in need of explanation.
The fact that an event is a pre-condition of its being observed does not explain the occurrence of the event!
LB said: The GHZ is well-documented on the web and it would take a great deal of time and energy to explain it, but if you are looking for answers I'm sure you can find them.
As I did. It was an interesting speculation. Even if true though the GHZ is *huge* and would probably include tens of millions or even hundreds of millions of star systems - all apparently capable of supporting life. It also seems to be based on assumptions arising from Earths single example which is OK as far as it goes but is open to serious questioning.
LB said: my point was that even among those with a bias against God and religion, the facts seem to suggest something fishy.
Not to everyone - myself included.
LB said: Otherwise his quote would have been dismissed as the ramblings of a jesus freak. As it is, it's dismissed because you don't agree with it.
I dismissed it because although it might not originate in theism it still carries the idea that we are somehow special or blessed with this particular universe which appears to have been designed for our kind of life. I do not agree that it is so & do not regard the Anthropic Principle as evidence for that belief.
LB said: As for the “laughable” anthropic principle, it seems you believe the term was coined recently by religious apologists.
Not at all. I am well aware of the ideas origins.
LB said: So if this "laughable" you are laughing at the work and opinion of some the this century's most notable scientists.
...and your point being? That scientists *can't* be wrong? Or that I should just slavishly follow their pronouncements? Strange as it may seem to a theist I actually have a mind of my own & can come to my own decisions about things.
LB said: The fact that an event is a pre-condition of its being observed does not explain the occurrence of the event!
Indeed. As far as I'm aware the Universal Constants were caused by fluctuations in the Big Bang because of randomness @ the quantum level. If this randomness had produced different fluctuations then the Universe would have been different to one degree or another. In other words - we got lucky. That seems far more reasonable (at least to me) than God saying 'Let there be Light'.
Interesting story!
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