Remember the “planetary autopsy” that told us that rocky dead planets are common, therefore ET life is common? Our physics color commentator Rob Sheldon, an experimental physicist who is also the author of Genesis: The Long Ascent, vols 1 and 1, offers some thoughts on their assumptions:
I haven’t had a chance to comb through the science paper that this journo article is based on, but it appears to have a huge assumption in the middle of it. That is, it never actually sees any evidence of rocky planets, gas planets, water planets, or planets of any kind. What it actually finds is evidence of oxygen ions in a white-dwarf star. Now white-dwarfs are pretty hot–which is why they are white–so any oxygen will be ionized and emit light. But the “standard model” for a white-dwarf lifecycle has them forming from stars no more massive than our Sun, which don’t get big enough to make oxygen. Therefore seeing oxygen in a white dwarf is presumably due to a thin layer of ground-up planets laying on the surface.
As I argued several years ago when the BICEP2 results claimed to have observed gravitational waves, a theory can have one whopping assumption, one tooth-fairy, but no theory is allowed to have 2 tooth-fairies. Why? Because I can prove anything with 2 assumptions, or to say it differently, if each assumption is of low probability, then two assumptions are an even lower probability than their product.
And this analysis has a minimum of 2 tooth fairies. First it makes an assumption that all white dwarfs are made the same way (despite evidence to the contrary). Then it makes the assumption that observed oxygen has to come from planets (rather than, say, comets, nearby supernovae, giant molecular clouds, etc.) and that the planet had to have lots of oxygen on it (despite, say, the examples of Mercury, Jupiter, Saturn, Uranus and Neptune). And finally it has to assume that the planet only recently accreted onto the white dwarf (despite the previous existence of a white dwarf as a sun-type star living for billions of years with the same planets).
I would argue that this is a very weak argument, mostly trying to jazz up a very boring data set or at least distract the audience from remembering the “standard candle” Nobel Prize assumed that all white dwarfs were identical. Either way, its a preposterous story attempting to distract from its most distressing results.
Researchers: Rocky dead planets common, therefore ET life common In case you thought this field was “settled science,” see also, recently: “‘Evolution’ says we are alone” and “Once again, for the thousandth time, we are “closing in” on alien life
In case you thought this field was “settled science”: “Evolution” says we are alone
Once again, for the thousandth time, we are “closing in” on alien life