We’ve posted several times about all the extra-solar planets that are constantly being discovered — much to the distress of creationists. The last time was 715 Newly-Found Extra-Solar Planets. The total of confirmed planets spotted outside our solar system is now nearly 1,700.
The article we found today at PhysOrg is different from the others, because it quantifies the number of planets in the galaxy that could sustain life. Let’s take a look at Milky Way may bear 100 million life-giving planets. Here are some excerpts, with bold font added by us:
There are some 100 million other places in the Milky Way galaxy that could support complex life, report a group of university astronomers in the journal Challenges. They have developed a new computation method to examine data from planets orbiting other stars in the universe. Their study provides the first quantitative estimate of the number of worlds in our galaxy that could harbor life above the microbial level.
Here’s a link to the paper: Assessing the Possibility of Biological Complexity on Other Worlds, with an Estimate of the Occurrence of Complex Life in the Milky Way Galaxy. You can read it without a subscription, but you’ll have to download it. Back to PhysOrg:
“This study does not indicate that complex life exists on that many planets. We’re saying that there are planetary conditions that could support it. Origin of life questions are not addressed – only the conditions to support life,” according to the paper’s authors Alberto Fairén, Cornell research associate; Louis Irwin, University of Texas at El Paso (lead author); Abel Méndez, University of Puerto Rico at Arecibo; and Dirk Schulze-Makuch, Washington State University.
At this stage in our galactic exploration, it’s amazing that they can estimate how many planets have such conditions. Let’s read on:
“Complex life doesn’t mean intelligent life – though it doesn’t rule it out or even animal life – but simply that organisms larger and more complex than microbes could exist in a number of different forms. For example, organisms that form stable food webs like those found in ecosystems on Earth,” the researchers explain in an auxiliary statement.
They’ve actually estimated the number of planets that can have more than mere microbes? How did they do that? We continue:
The scientists surveyed more than 1,000 planets and used a formula that considers planet density, temperature, substrate (liquid, solid or gas), chemistry, distance from its central star and age. From this information, they developed and computed the Biological Complexity Index (BCI).
We haven’t read the paper, but we strongly suspect that their methodology is more substantial than the fantasy computations of the Discoveroids for determining specified complexity. Here’s more:
The BCI calculation revealed that 1 to 2 percent of the planets showed a BCI rating higher than Europa, a moon of Jupiter thought to have a subsurface global ocean that may harbor forms of life. With about 10 billion stars in the Milky Way galaxy, the BCI yields 100 million plausible planets.
Is Europa their benchmark? Apparently so. This is from the paper’s abstract:
By our calculation only 11 (~1.7%) of the extrasolar planets known to date have a BCI above that of Europa; but by extrapolation, the total of such planets could exceed 100 million in our galaxy alone. This is the first quantitative assessment of the plausibility of complex life throughout the universe based on empirical data. It supports the view that the evolution of complex life on other worlds is rare in frequency but large in absolute number.
We’re not discouraged. There should be plenty of adventure in a galaxy with 100 million worlds at least as hospitable to life as Europa. Here’s one last excerpt:
“It seems highly unlikely that we are alone,” say the researchers. “We are likely so far away from life at our level of complexity that a meeting with such alien forms might be improbable for the foreseeable future.”
It’s probably a good thing that we’ve got some distance from any potentially competitive species. At this stage in our history, it might be a one-sided conflict — and it wouldn’t be in our favor.
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