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Comment by matthewdgreen | Hacker News Reader

I don’t know if Loeb is right or wrong about any of this (and I would find it much more exciting if he was right) but the “extraordinary claims require extraordinary evidence” saying really applies to Loeb on this one. To track an interstellar asteroid to a precise location on the ocean floor and recover pieces of it requires an extraordinarily precise chain of evidence, and if even a fraction of this article is accurate, that doesn’t feel justified here.

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Extraordinary claims require legitimate evidence. "Extraordinary" cannot describe evidence; all evidence is ordinary. What happened here is that the evidence was so bad as to be incapable of supporting any claim.

I'm not disagreeing hard, and we're just discussing words at this stage. But I wouldnt object to calling less commonly ocurring data points extraordinary.

The phrase I used is “extraordinarily precise.” When you’re conducting a medical trial of 10,000 patients there’s always a high probability (virtually a certainty) that one measurement will be inaccurate. You can live with this minimal error rate because there’s so much data that a small amount of error doesn’t invalidate the results. If you’re conducting an experiment involving a single asteroid, then every link along the chain of evidence had better be airtight, and validated to a level that wouldn’t be cost-effective or practical in other circumstances. There can’t be a 0.1% or a 1% or a 10% or (god forbid) a 50+% chance that the substance you’re presenting is something other than what you claim it is.

We probably are all familiar with the Fermi Paradox, but Issac Arther noticed it has a very interesting implication: Claiming that an alien probe has visited the earth is NOT an extraordinary claim.

Under very weak assumptions (basically that an intelligent race would have the desire and ability to explore the galaxy via self-reproducing probes) the galaxy should be crawling with such probes. Even at sublight speeds---and even if probes were only sent between stars when the stars naturally moved closer than a light year from each other just from their orbital movements around the galaxy--in a few million years the probes would be ubiquitous.

What is extraordinary is the negative evidence we get from not observing these probes. It means that there has never been even one intelligent species who had the technology and desire to explore the galaxy. Or even that there wasn't a small minority of them who wanted too--or even one Elon-Musk-esque individual who wanted to.

Given that we can almost do this ourselves (heck, if our own Elon Musk tried, I wouldn't bet against him succeeding) Avi Loeb's hypothesis that one of these probes might have hit the earth isn't an extraordinary hypothesis at all. We should expect to find these probes, and maybe we haven't found them yet because nobody has bothered to look for them.

The existence of Bracewell-Von Neumann probes is the one reason I don’t absolutely dismiss UFO believers out of hand. It’s actually a little bit surprising we don’t see intelligent machines in our neighborhood! But believing in this as a possibility is very different from renting a ship, sailing to a specific location, and saying “this is the residue of an alien probe.” Especially when the evidence you used to find the site is itself very shifty.

>The existence of Bracewell-Von Neumann probes is the one reason I don’t absolutely dismiss UFO believers out of hand

Bracewell-Von Neumann probes don't exist, as far as any can tell. You seem to be basing your credulity towards one unproven phenomenon on another unproven phenomenon. If anything, the fact that VN probes would in theory be easier than the sort of exotic physics breaking technology supposedly demonstrated by UFOs and yet the entire galaxy hasn't been consumed and assimilated as the math suggests should happen should cast even more doubt on UFOs.

That’s a weird statement coning from a self-replicating automaton that that meets many of the criteria required of a B-vN machine.

Except for the criteria that would let you could launch me into space and let me survive drifting through the radioactive vacuum for thousands or millions of years without harm, then allow me to self-replicate using any arbitrary matter I happen to encounter (as opposed to sexually with another member of my species, which is how humans normally replicate) then allow my progeny to repeat the process without significant failure over countless generations.

You know.. all of the actually difficult (thus far impossible) criteria and complexity that would required for Von Neumann machines to work in practice.

You think building self-replicating machines that can build themselves from a handful of common chemicals is the easy part? I think you’re very badly estimating the difficulty of that problem.

The isotope evidence strongly implies he's wrong.

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