Sun's Dark Companion 'Nemesis' Not So Likely 306
TravisTR passes along a story about the death of Nemesis. "The data that once suggested the Sun is orbited by a distant dark companion now raises even more questions... The periodicity [of mass extinctions] is a matter of some controversy among paleobiologists but there is a growing consensus that something of enormous destructive power happens every 26 or 27 million years. The question is what? ... another idea first put forward in the 1980s is that the Sun has a distant dark companion called Nemesis that sweeps through the Oort cloud every 27 million years or so, sending a deadly shower of comets our way. ... [Researchers] have brought together a massive set of extinction data from the last 500 million years, a period that is twice as long as anybody else has studied. And their analysis shows an excess of extinctions every 27 million years, with a confidence level of 99%. That's a clear, sharp signal over a huge length of time. At first glance, you'd think it clearly backs the idea that a distant dark object orbits the Sun every 27 million years. But ironically, the accuracy and regularity of these events is actually evidence against Nemesis' existence."
Re:How long since last time (Score:5, Insightful)
I predict a nuclear holocaust before then, honestly.
Re:Second comment debunks (Score:3, Insightful)
This is a complete fucking joke, and it's pathetic that you people are taking it seriously. Let's put things into perspective. The Earth's crust is about 5km thick under the oceans. It's about 3000km down to the outer core, with another 3000km down to the inner core. To say that this ridiculously thin crust is putting any significant pressure on that core is laughable, and shows that the comment writer really has no idea about basic geology at all.
Re:Second comment debunks (Score:4, Insightful)
Re:How long since last time (Score:2, Insightful)
This isn't GameFAQs, you're allowed to say fuck
Re:period of passing through the galaxy ecliptics? (Score:3, Insightful)
Some movement like that (through the galactic plane) could be a reason for some instability in the Oort cloud. The galaxy is chaotic. So many objects, all influencing each other. Lots of motion around several centers of gravity and oscillations through the galactic plane too. Sure, I can see that some (galactically speaking) relatively small objects such as a 10 km rock can change orbit a little.
We would have to prove that the instability sort of peaks every 27 million years. I hate statistics, so I am not going to try that :-)
Re:11 million years (Score:4, Insightful)
Well, average life-expectancy of a species is 5-million years. Homo Sapience has already doubled that putting us at the extreme end of the scale that gives this average.
In short, the chances of us being around long enough to need to do something is statistically negligible. Life will be around. Probably even intelligent life. Perhaps this time even life intelligent enough to do something, probably not.
If we were wiped out tomorrow, it's quite likely that zero evidence of our existence would even be around to be found 10 million years from now. There were entire species that we know existed because we have fossils, that were around longer than us - and where we know this because we have two bones. Not two skeletons - two bones.
The assumption that we're the first technologically intelligent species on this planet is just as unscientific as to assume we aren't. The absence of evidence in this case can be just as easily explained by deep time as that there wasn't anything to leave it. But we do have absolute proof that technological societies CAN evolve on earth - because we're here. Thus Occam's razor suggests it's more likely that it has happened before - probably several times than that it hasn't. ...sheez, and I just wanted to expand on your joke by mentioning how low the odds are of our species (or even of the entire class mamalia) still being around in 16 million years...
Re:11 million years (Score:5, Insightful)
We have no proof that we're the first, and frankly if we were extinguished tomorrow the statistical odds are that in 5 million years time there will be no single trace of evidence left that we were ever here. To assume that no species in the billion years or so prior to our arrival reached this level is... well it's absurd.
For a geologist it would be pretty trivial to figure out. Merely analyze the distribution and size of mineral deposits of various ages. Why thats odd, all of the coal that was near the surface 5 million years ago is missing, although the stuff thats buried "too deep" 5 million years ago is still here. Same game for oil/gas, oddly enough all the large deposits that were onshore or close to shore 5M years ago are gone, how odd. Another fun one would be our trash heaps. WTF is all this indium ore near all this relatively pure glass ore? How come we find silicon deposits from 5 million years ago that are occasionally ridiculously pure except for commercially useful P-type and N-type semiconductor impurities? Finally, assuming the highly evolved cockroaches that have taken over have advanced beyond us, they'd also notice that certain technologies that they use have not been exploited, 5M years ago they were obviously pretty good at burning this "oil" stuff but they clearly never figured out how to refine boron into anti-matter reactor shielding, or mined graphite to make monocrystaline carbon fiber space elevators, much like a hundred years ago hyperpurified silicon and large lumps of pure uranium metal were not industrially produced.
Re:11 million years (Score:3, Insightful)
So you assume a previous intelligent society would have used the same fuels as us (really ? Fossil fuels used by the "people" whose time fossil fuels were LAID DOWN IN... think about that for a second).
More than that, the very surface of the earth has been reshaped a few times. There was mass vulcanism in Siberia that covered whatever was there originally under about 2 miles of magma round about the same time as the KT event - in fact some scientists believe that the KT event could have CAUSED this... so if our hypothetical intelligent dinosaurs had been living there ... no trace we could find may have survived.
More-over all the stuff you mention are what, 100 years old ? So if we'd died out just a century sooner than right now - no evidence would have survived. We were a pretty advanced technological society even then though.
If what you say is so obvious - and so easy for a geologist to prove - then how come none has ? And no - they haven't. The vast majority of paleontologists and geologists believe it entirely likely that previous societies as technologically advanced as ours could have existed.
Carl Sagan said "Absence of evidence is not evidence of absence". That is true - though of course the corollary is too - it's not proof either.
Here's a little suggestion for you. Whenever you hear "there's no evidence for" as an argument against something being possible - ask three questions:
1) Has anybody looked ?
2) If they did - would they have expected to find anything ?
3) Is the odds of evidence simply being missing bigger or smaller than the odds of it never having existed ?
Here we have:
1) No
2) Maybe - depends who looked.
3) Definitely. So even if somebody looks expecting to find, they may find nothing despite it having once existed.
Re:11 million years (Score:3, Insightful)
True but voyager is only 30 years old. More-over - it takes a society who has reached space-travel MORE advanced than ours to find it. If the moon can avoid a meteorite in the are where we left stuff - that has much better odds -but again, would only be discovered by a society the develops far enough to GET to the moon.
Right now - we could have missed it by just 40 years. 40 years out of 3 billion (the age of the earth) is a pretty damn small window and we don't have ANY evidence to believe we will still be here next year - though right now the most likely cause if we're not would be ourselves. Considering we had the most viable means of destroying ourselves BEFORE we went to the moon nearly 50% longer actually)... well you see what I'm getting at?
The corollary is, a society more advanced than ours from the past may have left us a nice little "we were here note" somewhere else - perhaps we'll find it on the surface of Mars or one of Jupiter's moons waiting for our great great grandchildren. Mars would have looked like an ideal candidate even a few decades ago when we thought it had little weather and no major geological activivity - now some scientists believe it has periods of mass vulcanism on a fairly regular basis that basically resurfaces the planet (like what happens on Venus but not so regularly) - so that would make it a less suitable choice.
Even then, unless we go look, we won't know -and even if we look and find nothing it doesn't mean there was nobody to leave a note - it could just mean they weren't bothered to.
Re:How long since last time (Score:2, Insightful)
Nope. It's always been fine. Read the fine article. Read the fine manual. Your wife and I were fine last night. Always just been fine.
You must be new here. Geeks don't have girls in their lives... and to marry one???? ;-)
Re:period of passing through the galaxy ecliptics? (Score:3, Insightful)
No it fucking doesn't. Just because there's something you don't like doesn't mean you can pretend like it's not really there. "And their analysis shows an excess of extinctions every 27 million years, with a confidence level of 99%.". We're talking about hard statistical analysis, there's absolutely nothing that goes in the way of your bullshit "anomaly/bias/incomplete data" explanation.
If your interpretation of Occam's Razor is "if I can't see why things are the way they are then they mustn't be like this" you need to do some reading.