In the past few decades, thousands of extra-solar planets have been discovered within our galaxy. As of July 28th, 2018, a total of 3,374 extra-solar planets have been confirmed in 2,814 planetary systems. While the majority of these planets have been gas giants, an increasing number have been terrestrial (i.e. rocky) in nature and were found to be orbiting within their stars' respective habitable zones (HZ).
However, as the case of the Solar System shows, HZs do not necessary mean a planet can support life. Even though Mars and Venus are at the inner and the outer edge of the Sun's HZ (respectively), neither is capable of supporting life on its surface. And with more potentially-habitable planets being discovered all the time, a new study suggests that it might be time to refine our definition of habitable zones.
Welcome to the Inhospitable Zone.
(Score: 3, Interesting) by bzipitidoo on Tuesday July 31 2018, @05:38PM (4 children)
I'm guessing that near mindless microbial life is much more common than intelligent life. Consider Earth's history. For about 3 billion years, microbial life was all that existed on Earth. It's only the last 0.5 to 1 billion years that had animal and plant life, and then, life intelligent enough to begin figuring out the cosmos has been around for a mere 0.0002 billion years or so.
And, the microbial life of Earth changed radically over that long period. Early Earth had only trace amounts of oxygen in the atmosphere.
Getting into the Drake equation here. Our own solar system has just one out of 8 (or possibly 9 or 10 large planets) that support life, so far as we can tell at this time, though there is of course speculation about Mars mostly, and the larger moons such as Europa. Perhaps our moon gives Earth necessary rotational stability, without which Earth could chaotically heel over and stress life beyond the breaking point. If such is a necessary property of a habitable planet, that makes life a lot rarer. Maybe only 1 in 1000 solar systems will have life, and of those, possibly 75% or more will be microbial only.
(Score: 1, Interesting) by Anonymous Coward on Tuesday July 31 2018, @07:13PM (3 children)
Who told you microbial life cannot be intelligent? A single neuron isn't that much brainier than a bacterium; a single transistor, even less so; and still, a number of them exchanging signals is what produces intelligent thought, or at least simulates it.
Given a robust enough messaging protocol, a community of bacteria can do everything a brain of neurons or a chip or transistors can.
(Score: 2) by acid andy on Tuesday July 31 2018, @08:55PM (2 children)
It's an intriguing idea I want to happen and I'm sure it's possible. I can see some possible problems though. Once neurons in the brain have built a network of connections to one another, that pattern of connections mostly stays there for a long time. If you've got microbes that aren't physically attached to one another, perhaps drifting around in slime or a liquid, mightn't it be harder for them to maintain a single pattern of connections to one another? It might be possible to save state even when they move about if a microbe passed its state to a neighbor that drifted into its spot, before moving off itself, but only if there was some confidence that the new arrival would stay put in that place for a while. If they're all stationary microbes, it might solve that problem but I wonder if their communication might be slower to propagate and / or require more energy than in a dense, physically connected brain. Beyond that, what would they use the intelligence for? They'd be wanting limbs to start manipulating their environment. I suppose huge clusters of them could assemble en masse to move objects but by that point haven't you really just evolved a larger animal?
Just idle speculation and rambling on my part.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 1, Informative) by Anonymous Coward on Wednesday August 01 2018, @11:10AM (1 child)
Living cells always communicate using chemical signals, even in multicellular organisms and even in animal bodies. Neural cells are just an adaptation useful to shorten reaction times by electrically commanding release of chemical signals at remote cell boundaries.
Now, when you have a community of cells without specialized, channelized information pathways, then the selectivity of information reception must be achieved by some sort of chemical addressing and receptors specialized for each of the signals (and we still have those, it is "endocrine system", hormones and receptors). Supposedly, the "intelligence", or complexity of interactions and cooperation between undifferentiated uni-cells contained in group entities should be proportional to number of kinds of different receptors they have, but their decision making ability should be limited by the size of their group, unless some sort of hierarchy (tiers, like in neural networks) or specialization is introduced.
(Score: 2) by fyngyrz on Wednesday August 01 2018, @03:09PM
FTFY.
Also, our not-necessarily-complete experience in this is limited to this planet, something that in no way provides an ironclad framework for what might be going on on other planets and in other star systems. Ergo, "habitable zone" may well be complete nonsense.