Scrutable

basementer wrote: ↑

Mon Sep 14, 2020 6:26 am

I remember when there was discussion of what might have been microbial remnants on a bit of Mars rock, mid to late 1990s, Terry Pratchett said something close to "I want so much for this to be true that I hope the scientists are trying their hardest to prove that it isn't". I couldn't have phrased it better.

shpalman wrote: ↑

Mon Sep 14, 2020 7:56 am

Well I did find Phosphine Detected In The Atmosphere of Venus

It wouldn't be such a good sign if phosphine were detected in the atmosphere of my lab.

lpm wrote: ↑

Mon Sep 14, 2020 3:32 pm

shpalman wrote: ↑

Mon Sep 14, 2020 7:56 am

Well I did find Phosphine Detected In The Atmosphere of Venus

It wouldn't be such a good sign if phosphine were detected in the atmosphere of my lab.

Unlikely you'll hear anyone claim at @RoyalAstroSoc that they've discovered life on #Venus. Rather, they've found chemistry that current thinking would most likely suggest a biotic source. Just watch as organic chemists pop up with many feasible abiotic explanations

FlammableFlower wrote: ↑

Mon Sep 14, 2020 9:12 pm

lpm wrote: ↑

Mon Sep 14, 2020 3:32 pm

shpalman wrote: ↑

Mon Sep 14, 2020 7:56 am

Well I did find Phosphine Detected In The Atmosphere of Venus

It wouldn't be such a good sign if phosphine were detected in the atmosphere of my lab.

From that link:

Unlikely you'll hear anyone claim at @RoyalAstroSoc that they've discovered life on #Venus. Rather, they've found chemistry that current thinking would most likely suggest a biotic source. Just watch as organic chemists pop up with many feasible abiotic explanations

He's bl..dy psychic, he is. Made me chuckle anyway.

jimbob wrote: ↑

Mon Sep 14, 2020 9:34 pm

FlammableFlower wrote: ↑

Mon Sep 14, 2020 9:12 pm

lpm wrote: ↑

Mon Sep 14, 2020 3:32 pm

From that link:

Unlikely you'll hear anyone claim at @RoyalAstroSoc that they've discovered life on #Venus. Rather, they've found chemistry that current thinking would most likely suggest a biotic source. Just watch as organic chemists pop up with many feasible abiotic explanations

He's bl..dy psychic, he is. Made me chuckle anyway.

What sort of biological processes might produce phosphine?

K.R.M. Mackey, A. Paytan, Encyclopedia of Microbiology (Third Edition), 2009 wrote:The phosphorus cycle differs from the cycles of other biologically important elements, such as carbon, nitrogen, and sulfur, in that it lacks a significant gaseous component; nearly all phosphorus in the environment resides either in solid or in aqueous forms. The one exception to this rule is the volatile compound phosphine (PH3, also called phosphane), a colorless, poisonous gas formed in the environment from the breakdown of alkali metal or alkali earth metal phosphides with water. This process is poorly characterized and likely comprises various multistage chemical reactions. Microbially mediated phosphine production can be a major source of the gas in engineered systems (e.g., sewage treatment facilities and constructed wastewater treatment wetlands) where organic phosphorus is abundant and reducing conditions are common, suggesting that microbes could also play a role in phosphine formation in natural systems (although the direct enzymatic production of phosphine has not yet been identified). Although phosphorus can exist as phosphine, the gas does not persist in the environment owing to rapid autoxidation, precluding significant accumulation of phosphine in the atmosphere. Phosphine is therefore a minor component of the environmental phosphorus pool.

jimbob wrote: ↑

Mon Sep 14, 2020 9:34 pm

What sort of biological processes might produce phosphine?

bob sterman wrote: ↑

Tue Sep 15, 2020 10:32 am

jimbob wrote: ↑

Mon Sep 14, 2020 9:34 pm

What sort of biological processes might produce phosphine?

BBC specifically says "microbes living in the guts of animals like penguins"...

https://www.bbc.co.uk/news/science-environment-54133538

Think we have the answer...

bob sterman wrote: ↑

Tue Sep 15, 2020 10:32 am

jimbob wrote: ↑

Mon Sep 14, 2020 9:34 pm

What sort of biological processes might produce phosphine?

BBC specifically says "microbes living in the guts of animals like penguins"...

https://www.bbc.co.uk/news/science-environment-54133538

Think we have the answer...

dyqik wrote: ↑

Tue Sep 15, 2020 10:06 pm

Some of my colleagues are not entirely convinced that the claimed detection in the paper is actually a spectral line. And they are among the world's experts on detecting molecules in planetary atmospheres with the telescopes in question, and one is acknowledged in this paper.

I suggest you look at fig. 3 first, then fig. 1 and fig. 2 in the paper.

Additionally, pulling the line out of the background involves fitting a 12th order polynomial to the spectra, which is a potentially difficult thing to get right and not contaminate the data with.

jimbob wrote: ↑

Wed Sep 16, 2020 8:17 am

dyqik wrote: ↑

Tue Sep 15, 2020 10:06 pm

Some of my colleagues are not entirely convinced that the claimed detection in the paper is actually a spectral line. And they are among the world's experts on detecting molecules in planetary atmospheres with the telescopes in question, and one is acknowledged in this paper.

I suggest you look at fig. 3 first, then fig. 1 and fig. 2 in the paper.

Additionally, pulling the line out of the background involves fitting a 12th order polynomial to the spectra, which is a potentially difficult thing to get right and not contaminate the data with.

12th order polynomial.

Yikes

dyqik wrote: ↑

Tue Sep 15, 2020 10:06 pm

Some of my colleagues are not entirely convinced that the claimed detection in the paper is actually a spectral line. And they are among the world's experts on detecting molecules in planetary atmospheres with the telescopes in question, and one is acknowledged in this paper.

I suggest you look at fig. 3 first, then fig. 1 and fig. 2 in the paper.

Additionally, pulling the line out of the background involves fitting a 12th order polynomial to the spectra, which is a potentially difficult thing to get right and not contaminate the data with.

shpalman wrote: ↑

Wed Sep 16, 2020 8:03 pm

I know the polynomials form a complete set but I struggle to think of any physical reason for using such a high order one here.

basementer wrote: ↑

Wed Sep 16, 2020 6:54 pm

dyqik wrote: ↑

Tue Sep 15, 2020 10:06 pm

Some of my colleagues are not entirely convinced that the claimed detection in the paper is actually a spectral line. And they are among the world's experts on detecting molecules in planetary atmospheres with the telescopes in question, and one is acknowledged in this paper.

I suggest you look at fig. 3 first, then fig. 1 and fig. 2 in the paper.

Additionally, pulling the line out of the background involves fitting a 12th order polynomial to the spectra, which is a potentially difficult thing to get right and not contaminate the data with.

Could you clarify, dyqik, is it that a 12th order polynomial is usually used in this sort of analysis, although it's known to be tricky? Or that this is a novel technique that immediately looks risky?

monkey wrote: ↑

Wed Sep 16, 2020 8:22 pm

shpalman wrote: ↑

Wed Sep 16, 2020 8:03 pm

I know the polynomials form a complete set but I struggle to think of any physical reason for using such a high order one here.

They might not have had a physical model if they were using the 12th order fit just for smoothing or subtracting the background, but they should've tested for overfitting, did they do that?

(I've not looked at the paper)