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Comment by wizzwizz4 | Hacker News Reader

> The existence of atoms is not merely probable, after millenia of debate the question is settled. Everyone can perform an experiment to verify it.

Except atoms aren't atomic: they can be further subdivided. In the original sense of the word, we still don't know whether there are atoms.

> It means we have a statement for which we can generate additional evidence at will. No matter what your threshold for evidence needed is, it can be met.

Reading the same book over and over again only gives you evidence about what the book says, not whether the words in the book are true. Likewise, performing an experiment over and over again only gives you evidence about what the experiment does, not any models that generalise its results (beyond the marginal, diminishing-returns "we're pretty sure this experiment's results match up").

Nothing is ever beyond doubt; only beyond reasonable doubt.

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> Except atoms aren't atomic: they can be further subdivided

Those are two different facts:

  1. Atoms exist
  2. Atoms can be divided

GP was attesting to #1 being a scientific fact for which "no matter your threshold for evidence needed, it can be met". If you object to the word "atoms" on the grounds of it having a specific meaning from 2K years ago, replace that with "the modern standard model of particle physics".

>> > It means we have a statement for which we can generate additional evidence at will.

> Reading the same book over and over again only gives you evidence about what the book says

"Generate additional evidence at will" is packing a lot of stuff, but in my read it means "Generate a hypothesis", "Model a new experiment that can disprove it to the desired or available precision", "Review the experimental setup for any defects", etc etc.

"Generate additional evidence at will" when applied to the "scientific fact that atoms exist" means that any new experiment that you design and perform will be compatible to that fact. There is no evidence whatsoever that atoms (at their "level of abstraction") do not exist.

The only way I see out of that is if you're _so_ reductionist to the point where you accept that the _only_ thing that exists is whatever is at the lowest level of reality (quantum fields, quantum foam, whatever), but then I guess neither you nor I exist to be discussing this.

> "Generate additional evidence at will" when applied to the "scientific fact that atoms exist" means that any new experiment that you design and perform will be compatible to that fact. There is no evidence whatsoever that atoms (at their "level of abstraction") do not exist.

You're describing certainty. This is a prediction, not reality. A new experiment you design and perform might not be compatible with the existence of atoms; that's the whole point of running experiments! (Of course, I have the same prediction; the proton-neutron-electron theory of atoms seems like a pretty solid one, at this point.)

Certainty does have interesting properties, from a Bayesian perspective: if you are certain of something, there is no finite amount of evidence that'll convince you otherwise. (Of course, humans aren't ideal Bayesian reasoners; you can usually provide enough evidence to convince a certain person otherwise, if they are actually wrong.)

> You're describing certainty. This is a prediction, not reality.

I was being concrete about atoms, in particular, not about what gets named as a "scientific fact" in general.

Yes, in general you don't reach that threshold of being able to produce a stream of evidence that is always compatible to a theory, and you should not call that theory a fact (I also pointed that out on a different message). However for the existence of atoms, specifically, I do believe we have reached this level.

> Certainty does have interesting properties, from a Bayesian perspective: if you are certain of something

I don't literally believe with 100% certainty that atoms exist (because I may as well be a Boltzmann Brain hallucinating my entire universe). I say there will never come a time when we'll disprove the existence of atoms (at their level of abstraction).

> Generate additional evidence at will" when applied to the "scientific fact that atoms exist" means that any new experiment that you design and perform will be compatible to that fact.

There's a word for this, as I think it's fair to say any evidence of atoms still takes some inference and isn't a direct observation. The word is theory [1]. That is why we refer to the idea that matter is made of atoms as 'atomic theory',

Gould: "facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts."

[1] https://en.wikipedia.org/wiki/Scientific_theory

>GP was attesting to #1 being a scientific fact for which "no matter your threshold for evidence needed, it can be met". If you object to the word "atoms" on the grounds of it having a specific meaning from 2K years ago, replace that with "the modern standard model of particle physics".

Replacing the meaning of words isn't a minor point, it's the whole thing, and scientific definitions aim to be as strict as possible. If we decided to retire the word "atom" after the discovery of subatomic particles, nothing in reality would be stop existing, except this argument.

If we decided to call the electromagnetic field "the luminiferous ether" - defensible imo - we would be in a similar position. The concepts are incommensurate in similar ways, the word choice is to a degree a historical accident.

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