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Comment by memetomancer | Hacker News Reader

Press conference summary: Phosphine confirmed, abiotic pathways ruled out, need to send a spacecraft to learn more.

Assuming the study has no fatal flaws there really are no uninteresting explanations for the phenomenon. If we eventually discover there are abiotic pathways we didn't know about, that's really interesting. If we discover life and it's traced back to the earth somehow, that's riveting. If we discover life and it's alien, that's obviously extraordinary.

abiotic pathways ruled out

To the best of the reasearchers' knowledge: All known pathways to produce phosphane couldn't explain the observation (they were talking several orders of magnitude off). Abiotic 'exotic' chemistry is still an option (ie the 'unknown unknown' hasn't been ruled out).

You don't need to state the obvious.

It's impossible to rule out an "unknown unknown" by definition, because if you did then it wouldn't be "unknown" anymore.

No-go theorems exist (conservation of energy for example, hence no perpetual motion machines). Instead, they tediously had to exclude any process they could think of one by one.

> No-go theorems exist

That's K-K, not U-U.

There are known abiotic pathways. They've been ruled out.

There are unknown biotic pathways known to exist (from the press conference, biotic phosphane production on earth apparently still has some large question marks attached?).

There might be unknown abiotic pathways ('unknown unknowns'). In principle, there could be some clever way to rule them out based on the constraints of the Venusian environment.

Humans don't have nearly as much experience dealing with conditions like we find on Venus, so it's entirely possible this is a yet-unknown chemical reaction. Most chemists don't like dealing with blazing hot highly pressurized strong acids all day long.

>need to send a spacecraft to learn more

A sample of aliens can help leapfrog our understanding of biology, just like the study of terrestrial bacteria allowed us to precisely edit genes. Really interesting things happen biologically in extreme conditions.

I didn’t hear any geological explanations in the press conference. It would be interesting if there was some chemical process happening deep under the surface, where the necessary pressures are present, then have it introduced into the atmosphere through seismic activity. I’m not too familiar with Venus’s geology. I don’t think the core is molten, but the tidal forces from the sun must be significant.

The Sun's tidal forces on Venus are only 2.6x the Sun's tidal forces on the Earth, which is less than the tidal forces we get from our moon.

(This estimate assumes that tidal forces are proportional to 1/R^3 and that the orbital radius of Venus is 73% of Earth's)

The authors of the paper estimated that at least 200 times more volcanic activity than what’s present on the Earth would be required to release that much phosphine into the atmosphere. It’s almost certain that there are active volcanos on Venus, but that much activity is unlikely to have gone unnoticed.

If there was that much volcanic activity we'd expect the atmosphere to be contaminated with ash wouldn't we?

How can they rule out abiotic processes? It's a bit early for that. That seems far more likely than germs on venus. We'll be lucky to find them on Mars or Titan or Io. Highly doubt there is anything on Venus

I would agree the skeptical approach is healthy. As the scientists involved mentioned in their live stream, there's definitely more work to be done to gather more information, and figure out why this substance is where it shouldn't be.

They were pretty clear in stating up front they have not ruled out abiotic processes, and are not declaring that they have discovered life. They state based on the known conditions of Venus and known chemical pathways to phosphine, and what is known about phosphine as a bio-marker, that life is a distinct possibility.

Through further research either we'll learn something new about Venus, phosphine production (which could improve our understanding of its relevance as a biomarker in the universe), or confirm some form of biological process.

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