In which we muse on panspermia and the decline of once-great astronomers into crackpots.
[Approximate true-color image of the Venusian surface taken by the Soviet Venera 13 probe in 1982. Images take from the NASA NSDCC photo gallery.]
While browsing the science section of the BBC news online last week I came across the provocatively titled article "Life from Venus blown to Earth".
Many people are aware that temperatures at Venus's surface are a blistering and thoroughly inhospitable 480 °C (896 °F) or so, too high for any life as we know it (the lack of water is also a major problem) thanks to a run-away greenhouse effect. However, high in Venus's atmosphere there is a layer that with temperatures and pressures that are closer to that of Earth, and it has been seriously suggested that primitive life akin to bacteria might survive in the atmosphere (I haven't managed to track down a reference to the originator of this hypothesis).
Furthermore, panspermia (the idea that primitive life might be spread through the solar system or even the galaxy on material ejected by asteroid/comet impacts, among other mechanisms) is a not a totally kooky idea - a moderate amount of sober and serious scientific research is published in reputable peer-reviewed scientific journals each year (it is also a staple of science fiction, most often used to excuse the author's extreme laziness and lack of imagination in populating their fictional universe with large numbers of species of intelligent bipedal tetrapods that somehow often look more similar to humans than humans do to chimpanzees. They also want to mate with the captain of the human's space ship and occasionally rip his thin tee-shirt - this is in fact a robust prediction of many published models of panspermia). Wikipedia's article on panspermia is of reasonable quality, and so worth a read if you're interested.
This ADS abstract query returns all the peer-reviewed articles containing "panspermia" in their abstracts, and it appears to generate of order 5 papers per year, mainly in Astrobiology journals (IJAsB, AsBio) but occasionally in Astrophysics and Space Science (Ap&SS) which is often really a form of conference proceedings rather than a traditional peer-reviewed journal.
I would hazard a guess that most professional astronomers consider panspermia to be unlikely to be true (in particular on scales larger than the Solar system), but interesting and worth some research none the less on the off chance it might be important - that is my view of the subject in any case. Anyway, I followed the link to the BBC article in the hopes of reading something interesting...
Life on Venus could be blown to Earth by powerful winds, scientists claim. Previous research has considered the possibility of micro organisms existing in Venus's atmosphere despite extreme temperatures on its surface. But two scientists at the Cardiff Centre for Astrobiology say microbes from Venus could actually be blown into the Earth's atmosphere by solar winds. Their findings follow analysis of data from the European Space Agency's Venus Express probe, launched in 2005.All seemed well, until I read the next sentence, at which point alarms bells started ringing in my head and my skepticism levels surged from mild to extreme.
Prof Chandra Wickramasinghe and Dr Janaki Wickramasinghe claim Venus's clouds contain chemicals that are consistent with the presence of micro organisms.So let me explain why I'm not going to bother reading the actual Ap&SS article that sparked the news story.
Professor Chandra Wickramasinghe is quite a famous astrophysicist, and was a long-time colleague and collaborator with the even-more-famous (or infamous) Sir Fred Hoyle. In fact as a teenager I read popular science books co-authored by Hoyle & Wickramasinghe that were in the public library. Let us discuss Hoyle for a while, but as you'll see Chandra Wickramasinghe will naturally enough re-enter the story later.
Hoyle is most famous in general conception as the originator and main proponent of (now very thoroughly disproven) Steady State Cosmology, and ironically as the originator of the term "Big Bang" for the competing cosmological theory that now bears that name (it may or may not be the case that he used Big Band in a derisory sense). \
Hoyle is an interesting, even tragic, character - his early work, in particular on nuclear astrophysics and the generation of the elements (e.g. Burbidge, Burbidge, Fowler & Hoyle, 1957, Rev. Mod. Phys. 29, 547 - 650), is still very much the foundation of modern astrophysics, and Hoyle is remembered favorably and fondly in the astrophysical community for that work.
But by the later half of his career he ended up being considered also as something of a kook or a quack. Some of that was because of his (and a very few others) refusal to see or admit that Steady State Cosmology was increasingly inconsistent with the growing body of observational data in favor of the Big Bang. Hoyle continued to flog the dead horse of SSC well beyond the point the paradigm shift in favor of Big Bang cosmology had occurred, and in doing so made himself appear unscientific and contrarian (rather than being some sort of principled non-conformist).
That is not to say we astronomers do or must all think the exact same things. At the "working edge" of astronomical research disagreement between different astronomers is very much the order of the day. Astronomers can quite reasonably and rationally disagree about General Relativity verses Modified Ordinary Newtonian Dynamics, whether the Big Bang had a actually beginning, or whether it was preceded by a Big Crunch. But all professional astronomers agree that the Earth orbits the Sun, and those people that don't believe that are almost certainly not scientists.
Similarly scientists prefer clean simple theories that don't need lots of fine-tuning, because in general anyone can made an arbitrarily complex theory fit any data and at that point you've lost all hope of actually having either useful predictive power and/or hope of falsifiability. By the 1990's the additions Hoyle and colleagues had made to the Steady State Cosmology (now renamed the Quasi Steady State Cosmological Model: Hoyle, Burbidge, & Narlikar, 1993, ApJ, 410, 437), e.g. the precisely shaped metallic needles required to create a 2.7K microwave background without a Big Bang, appeared to the rest of us as little better than the epicycles upon epicycles in the flawed Ptolemaic system of planetary motion.
The other reason that many scientists (and not just astronomers) started to view Hoyle as a crack pot was that by the 1980's Hoyle was saying all sorts of really weird stuff. One telling example is that Hoyle, Wickramasinghe and Spetner
claimed that the feathered and winged dinosaur fossil Archaeopteryx was a fake (they seem to have ignored the fact that there where least six Archaeopteryx specimens known at the time). Why would they claim that?
Further info regarding the claims and evidence against can be found in the TalkOrigins FAQ "On Archaeopteryx, Astronomers, and Forgery".
Others might be deterred but Hoyle and Wickramasinghe have replied with Archaeopteryx, The Primordial Bird a book published in London by Christopher Davis in 1987. In it they repeat their claims in addition to advancing the notion that evolution proceeds in sudden fits and starts as a result of genetic storms of viruses carried to the earth from outer space. "Egads," you might think "where is the line between science and science fiction?" Molecular biologist have reacted with embarrassment to these mystical outpourings and have replied that there exists not an iota of evidence to support these wild theories. In a review of the book in New Scientist (10 September, 1987) Beverly Halstead writes;"This contribution [is] one of the most despicable pieces of writing it has ever been my misfortune to read. It displays utter contempt for minimal standards of scholarship ... [and] will remain for a long time a stain on the reputation of both authors."Not an ambivalent response.
Basically Hoyle and Wickramasinghe thought that Archaeopteryx must be a fake because its a fully functional intermediate (or "missing link") between reptiles and birds, i.e. consistent with the scientific theory of evolution, and hence (if not fake) would be evidence against Hoyle's pet idea that viruses from outer space (see, we are back to panspermia) change one type of animal into something very different ala hopeful monsters (only monsters from outer space!). One minute you're happily a standard four legged lizard, then you get a cold (from space!) and sprout wings, no fully functional intermediates allowed. I kid you not.
So perhaps you can now see why I suddenly lost confidence in the plausibility of the "Bacteria from Venus" story (or as I call it, the Venusian Pox, as it has a nicer ring to it).
In a later post I'll discuss more interesting-but-horribly-wrong Hoyle ideas, and the possible reasons behind them.