Discussion between DevSolar and elliot svensson

12:10 PM

@elliotsvensson: I will use an example completely unrelated to science to make my point here.

I am right now looking at a website that is telling me the exchange rate of EUR to USD is 1.1344$. Is that "true"? Yes. Does it mean that I can expect to get exactly that exchange rate if I go to my local bank and buy US dollars? No.

Because the bank will give me a different rate. YOUR bank will give you a different rate. In another country I will get a different rate. Anybody in the business of exchange rates knows that when looking at that number 1.1344$.

Which means that it is not necessary to qualify that number with "at this point of time, number might change with no further notice, at stock exchange X, additional charges apply".

It would be more correct, but it would also add a lot of unnecessary noise. So textbooks state that the universe is 13.8 billion years old instead of "13.799 ±0.021 billion according to the latest scientific consensus as of 2018".

And so the Khan Academy states that photosynthesis appeared 3.5 billion years ago. That's definitely good enough for a passing remark in a High School level textbook.

If you would be looking at material intended for people actually researching the origins of photosynthesis (like that Cardona paper we talked about earlier), you will find a much more nuanced and detailed discussion of the subject, dissenting opinions, alternative interpretations etc. etc. pp. -- but at the High School level, the teacher will probably be happy if the kids will get the order of magnitude right and move on...

elliot svensson

3:01 PM

@DevSolar, for comparison, let's read Khan Academy's stuff about dark matter: khanacademy.org/partner-content/amnh/the-universe/universe/a/…

What does the Universe contain?
The universe is made up of matter and energy. Visible, or normal matter, makes up everything we can touch and see, including ourselves, dogs, trees, planets, and stars. In the last 20 years we’ve discovered that this makes up less than 20% of the total mass of the universe. All the rest of the mass appears to be made of an invisible substance called dark matter. It emits and absorbs no light, but we can observe its gravitational effect on normal matter. Dark matter holds together the collections of stars called galaxies, and determines where galaxies gather t…

(previous pasted from link)

Instead of saying, "80% of the universe is dark matter, which emits and absorbs no light" the webpage specifically calls-out the "how we know" and "how well we know" aspects of these facts. They say "appears to be made of" instead of "is", and they repeat redundantly that it's invisible and it emits and absorbs no light.

This is warranted! We don't really know what's going on, but scientists have a consensus that "this is what it appears to be".

Instead of writing "photosynthesis appeared 3.5 billion years ago", textbook authors should write "we believe that photosynthesis appeared 3.5 billion years ago".

@DevSolar, I think there's an apples-oranges issue with your comparison to the exchange rate. It is not necessary to talk about the different fees and dynamics in order to quote the rate, but even so you would still tell high-schoolers that the rate changes every month (or every day).

DevSolar

3:39 PM

There has been no direct evidence so far of either dark matter. We have made certain observations regarding astrodynamics that indicate we cannot "see" about 80% of the total mass of the universe, but as to the actual nature of dark matter we are pretty clueless.

In contrast to that, we have paleontological *evidence* of 3.4Myr-old photosynthesis (e.g. http://www3.geosc.psu.edu/~jlm80/Geosc497/Tice&Lowe2004.pdf, just one of the references given in the Cardona paper).

elliot svensson

@DevSolar, you meant 3.4Gyr, right?

DevSolar

Arg. Decimal point vs. decimal comma, and my being not familiar with the Myr / Gyr notation. The source read 3,416 Myr, and I mistook that as a decimal.

elliot svensson

@DevSolar, no biggie... I do that all the time.

@DevSolar, the 3.4 Gyr measurement is astronomical, not geological.

DevSolar

Anyway. Why don't you come out in the open with the agenda behind your "skepticism". You don't agree with the definite wording used by e.g. the Khan Academy, and would prefer them to sound more cautious. Care to elaborate why you think that would be necessary, despite the scientific evidence?

elliot svensson

@DevSolar, if it's not clear already, I don't think that "coming out" will help any.

DevSolar

3:51 PM

Oh, I think I know where you're coming from alright. I'd just like you to say so yourself.

elliot svensson

I'll tell if you tell

DevSolar

Or, to turn the question around. You criticize the Khan Academy being "uncritical" about the 3.5 Gyr photosynthesis history. What is your reason to be critical about it, facing the evidence?

And please don't come up with the FYS paradox again. There is evidence for photosynthesis 3.5 Gyr ago, so obviously it happened. That we can't quite explain exactly how this matches with our understanding of stellar and atmospheric dynamics doesn't change this.

elliot svensson

@DevSolar, the date of 3.5Gyr itself is called into question, since its origin and its contradiction both lie with the stellar dynamics.

DevSolar

That just means we cannot explain the "why", it does not call the fact itself into question.

As Neil said about the dinosaurs. A couple of decades ago, all we knew was that they went extinct, we did not know why. But they did go extinct.

elliot svensson

@DevSolar, that extinct land-dwelling dinosaur species are extinct is instantly confirmable to anybody nowadays... not so with 3.5 Gyr.

DevSolar

4:02 PM

You got your priorities wrong.

elliot svensson

@DevSolar, 3.5 Gyr is a synthesis of the astronomical model with some local mineral samples. If the astronomical model doesn't back-up the astronomical model, then I think it's OK to be skeptical about the astronomical model.

DevSolar

There are several, independent, peer-reviewed works proving the 3.5 Gyr number. There is supporting evidence that there *was* liquid water in that timeframe. This is why it is *called* the FYS *paradox*. Scientists are, evidently, accepting that there was liquid water, and that there was photosynthesis 3.5Gyr ago, and are focussing their efforts on finding the explanation for the FYS paradox.

And you demand that they instead doubt the mutually-supporting evidence that there *was* water, photosynthesis, and generally, life on earth -- and instead, based on some astronomical and geophysical …

I'm out of here, I don't think there's more to be said.

elliot svensson

4:21 PM

@DevSolar, I would be happy, first of all, if the question got an Answer on Skeptics. My favorite answer would say, "Scientists know W, X, and Y about the origin of photosynthesis, and they believe Z. So, you know, it would probably be less-than-accurate to say that Z in a textbook. It would be better to say 'scientists believe Z' rather than 'Z' whenever this appears, like they already do in discussions about dark matter / dark energy."

elliot svensson

4:34 PM

@DevSolar, the astronomical model that we know to be incomplete also provides the 3.5 billion year figure; what we know about early life, water, photosynthesis can only be dated to 3.5 billion via astronomical model.

DevSolar

5:11 PM

You're suffering from a severe case of confirmation bias. You have gotten all the information you are lilely to get. But what you actually WANT is seeing your conclusion heralded "officially" on Skeptics.SE...

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Discussion between DevSolar and ellio…