There's almost certainly some form of life out there...
Anyone have any sources for this? All I’m getting is the Drake Equation, and that depends upon variables no one can fill yet.
Recently, thanks to Kepler and similar, many more of the variables have been filled in, and thus far, in the least conservative ways thought possible. Likewise, there are indications towards some of those remaining that they too might be pretty high.
For example, experiments with the building blocks of life (well known to be the most common elements and such in the universe), have found that RNA's base pairs can be easily created through simple processes. Or to be more precise, they mixed up chemicals thought to be common on the pre-biotic earth, and with exposure to sunlight, several of the RNA bases began to form on their own. That combined with RNA-world hypotheses for the origin of life seem to present a fairly good chance of the formation of replicators, though the exact processes could occur in a number of more or less plausible methods.
Some of the bigger hurdles are actually after the formation of life. For example, it isn't know how easy the transformation from unicellular to multicellular life is. On this planet, it took much longer than the formation of life, as well as much longer than the transformation from multicellular life to intelligent beings.
Of course, the ultimate question is how long intelligent life lasts. That's really the trickiest part of the equation, and really cannot be answered adequately through any means other than through learning of thousands of alien civilizations which died and flourished. Which will obviously never happen, even if we were to discover several instances of intelligent life in the universe.
As to some of the points brought up by others regarding weird life, it is indeed possible, but it is quite limited. Silicon based life which replaces our carbon with silicon (the next element in the same spot on the periodic table) would be much more delicate due to the different properties, as well as being less likely to form simply because of the quantities available in the universe. Less common element means less common planets with an abundance of that element, which in turn means a lower chance of it forming into life. Likewise, elements towards the beginning of the periodic table tend to be better for life due to other chemical reasons. So while it could be different on that level, it is much more likely to be carbon-based (or post-carbon based, as in the case of technological evolution).
(as justification for some of my earlier points) Complex life will likely also be cellular, as is seen with Earth's, simply because it becomes almost impossible to create a stable replicator without first having some form of containment which separates the organism from the environment. It could be a 'cell' as simple as the shell of a virus or more complicated than those seen on earth, but it would still likely be cellular. Cells have a size limit due to the physics of them, and so multicellular life would be required to maintain a cellular structure at the low level while allowing for further growth in size.
Also, all the alien conspiracy theories are unadulterated bullshit which are collectively less creative and have less merit than Twilight. The original 'ancient aliens' crap came from
Erich von Daniken, about whom Carl Sagan shares these kind words:
"That writing as careless as von Däniken's, whose principal thesis is that our ancestors were dummies, should be so popular is a sober commentary on the credulousness and despair of our times. But the idea that beings from elsewhere will save us from ourselves is a very dangerous doctrine - akin to that of the quack doctor whose ministrations prevent the patient from seeing a physician competent to help him and perhaps to cure his disease."
"I also hope for the continuing popularity of books like Chariots of the Gods? in high school and college logic courses, as object lessons in sloppy thinking. I know of no recent books so riddled with logical and factual errors as the works of von Däniken."
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Topic: Aliens & Stuff (Read 18646 times)