The problem I have with the Panspermia theory is that it violates Occam's razor.
There is a vast difference between something being "not impossible" and being "probable".
Scientists have been speculating for years now that comets might have seeded life on Earth, but a Japanese team has performed an experiment that shows it's a valid possibility. Dr Haruna Sugahara from the Japan Agency for Marine-Earth Science and Technology in Yokohama, and Dr Koichi Mimura from Nagoya University built …
This doesn't have anything to do with panspermia though, despite the article's misleading use of the word "seeded". Start with a soup of basic chemicals including amino acids, hit it very hard, and some of those amino acids can get smashed together to make peptides. I expect this would work just as well if the amino acids were on Earth and got hit with a rocky asteroid.
Occam's razor isn't an absolute. It certainly can be wrong
More precisely, it's an observation about probabilities that should be applied to a probabilistic model, not used as a filter. A Perfect Bayesian Reasoner always implicitly applies Occam's razor, which is simply a matter of acknowledging that multiplying a positive number by a value in [0,1) results in a smaller product. Thus "multiplying entities", to paraphrase Punch's gloss of William of Ockham's principle,1 reduces the overall probability of the thesis, if each "entity" has a non-zero probability of being incorrect.2
1Wikipedia has a nice summary of the tortured path of attribution and paraphrase by which we get the various phrasings.
2Prolepsis: Yes, I'm aware that Punch is using "multiply" here in the sense of production, not in the arithmetical sense, as he predates modern probability theory. His version, like William's, is an informal grasp of process that we have since formalized, in basic probability theory and in more complex ways such as various Bayesian models.
Occam's Razor can't be wrong: it states that usually a simpler explanation is more likely than a more complex explanation to be correct - it certainly doesn't rule out the occasional bizarre or convoluted explanation that may in fact be true.
"The problem I have with the Panspermia theory is that it violates Occam's razor."
My problem is that even if it turns out there is a simple and reliable mechanism for panspermia to work, where and how did the "first" life come into being? And THAT is what we are looking for whether panspermia is real or not.
Well Martin Budden seems to have solved that... take a planet/body/thing which has amino acids on it. Hammer it with some meteors/asteroids and you get peptides. leave it a while to develop into more life-y stuff then thwack it with a very big asteroid, spraying some of that stuff off and into space.
Repeat over billions of years and million-to-one chances happen in their thousands. Life only needs a few hundred million years to go from soup to people.
Hardly beyond imagination.
Panspermia is the simplest theory. If Panspermia doesn't happen, you need to explain why not. If life arises on Mars, why wouldn't it contaminate Earth (given that we've found Martian meteorites here)? What's so special about Earth that it's the first place ever for life to arise?
That said, personally I see Panspermia as a "get out of jail" card. If suggests that even if life could not have arisen on Earth, it could have arisen somewhere else and then migrated here. It vastly increases the range of habitats that life could have first arisen in. It's possible that it actually needs a Mars-like planet for the early stages, and then an Earth-like planet for the later stages. In that case life would be relatively sparse in the Universe, but overall Panspermia makes life more likely by increasing the options.
Eh? What? And this didn't make the news around the world and radically change the way we think about life?
No; because it didn't happen and it's highly dubious "science" from an unreliable source. http://doubtfulnews.com/2013/03/fossil-claims-from-the-fringe-life-in-a-meteorite-not-likely/
So they have shown that an impact can cause amino acids to fuse into peptides. That doesn't necessarily imply that the amino acids arrived from space.
Couldn't that also mean that an impactor caused locally available amino acids to fuse into said peptides?
I much prefer to source produce locally, think of the air miles and carbon footprint. ;)
Couldn't that also mean that an impactor caused locally available amino acids to fuse into said peptides?
So it's an experiment that failed to disprove a hypothesis, added to the body of available knowledge, and raised more questions as well? Sounds like science. Carry on.
"This was confirmed again in 2013 when fragments of a comet that exploded over Sri Lanka were collected. Analysis of the remains found non-terrestrial life, including a complex, thick-walled microfossil similar to plankton, within the comet's remains."
U wot mate? The fact that this is the first I've heard of that, which should have been the biggest scientific discovery ever, makes me think it must have been debunked pretty quickly.
"U wot mate? The fact that this is the first I've heard of that, which should have been the biggest scientific discovery ever, makes me think it must have been debunked pretty quickly."
Phil Plait got there pretty fast. There's some useful further debunking links in this one.
My organic chemistry knowledge is basically zero, so the part I'm not following is why it is more likely that these chemicals would have originated from a comet than from lightning striking primordial soup, or whatever the currently favoured terrestrial theory for the origin of complex proteins is.
Are these chemicals more common on comets than they would have been in an early terrestrial environment? How did they get onto the comets in the first place? Did they just happen there? Is the universe surprisingly high in protein?
"peptides, which – given a few billion years – could have evolved into higher forms of life"
Apart from the fact that peptides aren't a form of life (they're just peptides) in much less than a few billion years they'd have degraded. Heat, UV, oxygen, free radicals are all quite destructive given passage of time.
A peptide is just a bunch of amino acids held together with peptide bonds. A peptide bond is what you get when the amino- part of one molecule reacts with the acid part of another, eliminating a water molecule. You get the same result heating a bunch of amino acids together in a flask.
In other words, this so-called experiment is proof of absolutely nothing other than the fact that amino acids react with each other when heated. Wup-de-do.
Now if you take stuff like ammonia, methane, water etc. and whack them producing amino acids, even the simplest like glycine, then you have a result. Sort of.