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Comment by mdaniel | Hacker News Reader

> New evidence > ... > The team has used computer simulations to help explain what features distinguish the two liquids at the microscopic level

I regrettably(?) don't have the physics background to interpret the actual paper (linked in the sibling comment), but saying "computer simulations" are "evidence" seems suspect to me

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And Albert Einstein only had pencil and paper!

https://press.princeton.edu/books/paperback/9780691171074/ei...

"The book examines Einstein’s theory of general relativity through the eyes of astronomers, many of whom were not convinced of the legitimacy of Einstein’s startling breakthrough. These were individuals with international reputations to uphold and benefactors and shareholders to please, yet few of them understood the new theory coming from the pen of Germany’s up-and-coming theoretical physicist, Albert Einstein. Some tried to test his theory early in its development but got no results. Others — through toil and hardship, great expense, and perseverance — concluded that it was wrong."

I think it is a reasonable position to maintain, then, that there was insufficient evidence for GR until at least the Eddington experiment. That the derivation may have seemed so inevitable to Einstein once he saw it, or that its elegance was so pleasing, is not enough.

For a more modern example, String Theory is a very attractive hypothesis to many physicists, but as yet remains beyond the reach of experimental physics. Pursue it, by all means, if the elegance makes you think you're hot on the heels of the truth, but don't jump the gun and say we have evidence if the only experiment you can run is a computational thought experiment.

In the case of the water research, what's been shown is that some computational models (read "approximations") of how water behaves matches this old hypothesis that's been posed. But no experiment was conducted to show that real live water behaves this way.

Granted, it looks like the researchers did this for three _different_ models and found corroboration among them, and are saying that gives the result more punch.

I don't think folks here are trying to say this computational approach is invalid. I think there's a justified quibble with calling it "evidence" of a real world phenomenon that has never been observed.

Also, as with GR, there’s an experimental observation that doesn’t fit with the simpler model. For GR, it was the Michelson-Morley experiment, which showed that the speed of light is constant, for this, it’s “the anomalous behaviour of its thermodynamic response functions upon cooling, the most famous being the density maximum at ambient pressure” (https://www.nature.com/articles/s41567-022-01698-6.pdf)

So, basically, there’s a reigning theory that correctly describes lot of observations but then, a loose end is discovered, and theorists try to find the simplest theory that fixes that loose end.

I think string theory is different. There are no observations that show the existence of loose ends, only a desire to have a quantum theory of gravity, or even a Grand Unified Theory (https://en.wikipedia.org/wiki/Grand_Unified_Theory)

> For GR, it was the Michelson-Morley experiment, which showed that the speed of light is constant

The Michelson-Morley experiment did not show that the speed of light is constant, that was known for some time before; and it and was the basis for Special Relativity, not General Relativity. The Michelson-Morley experiment showed that there is no "frame dragging" - that, if there exists a "luminiferous aether", it is not itself moved by the movement of the Earth through it, as would be expected for any normal substance.

General Relativity was necessary as a theory to bring back gravity (and describe acceleration) in the context of SR (since SR requires the speed of light to be constant and finite, but Newtonian gravity is instant). It was experimentally confirmed 42 years after the Michelson-Morley experiment, by confirming the gravitational lens effect in a solar eclipse.

> I think string theory is different. There are no observations that show the existence of loose ends, only a desire to have a quantum theory of gravity, or even a Grand Unified Theory

The lack of a quantum theory of gravity is a huge gap in our understanding of the world, not a simple desire. Quantum mechanics makes obviously wrong predictions when adding gravitational effects (even worse if trying to account for curved space-time). General relativity makes wrong predictions about the behavior of elementary particles. So, we are left today without a model of how the world works - and the precise missing piece is "quantum gravity".

Of course, it may well turn out that in fact we need a completely new theory that would replace both QM and GR - but what we know for sure is that QM and GR as they are right now are not correct, and the most obvious incongruity is quantum gravity.

You're right about a GUT though - that would be nice to have from a mathematical beauty point of view, but it's not in any way required, unlike quantum gravity.

"or that its elegance was so pleasing, is not enough."

Yes, see "Lost in Math"

Albert Einstein produced a new theory, not new evidence. I maintain that language continues to mean something.

>And Albert Einstein only had pencil and paper!

And a slide rule, it's not like he needed to write every calculation.

But as far a I know, Einstein's General Relativity solved a very concrete problem: previous theories couldn't explain the orbit of Mercury.

General Relativity matched the observations, if wasn't just pen and paper or simulations.

And much more important to the discussion: The models Einstein produced matched existing reality, and also made predictions. Those predictions where eventually tested by other scientists with new experiments that matched Einstein's model's predictions, so the outcome of those experiments are now evidence that those models are correct.

This paper has a model, that hopefully and presumably, accurately describes real world phenomena, and it has been interrogated to produce a new prediction. Now someone has to devise an experiment to verify or reject this new prediction. Until that experiment is run, and the results found, we have no new information about how water behaves. All we have is a new way to verify or reject this model. If a later experiment confirms what this model predicted, then we will know something new about the world, and these simulations will be trustable in a new domain.

Evidence is not proof, it is evidence. It is still valuable because it can guide the way to experiments that give us empirical proof, or refutation of the conjecture.

It behooves the authors to present the limitations of the study. Lay people, unfortunately the majority, will interpret this to be definitive.

>Lay people, unfortunately the majority, will interpret this to be definitive.

They're not the target audience of scientific papers.

On top of that, the linked article is simply a press release and not the research paper itself. Papers usually list limitations and such, that's very normal

This leads me to a different path. Some (most?) papers require an almost absurd amount of context; in the extremes, single digit audiences with the knowledge to understand.

Perhaps putting that context into publications would be more effective?

> Perhaps putting that context into publications would be more effective?

It's called introduction

You’re describing a pop science book, and of course people write those too.

But research publishing is a traditionally internal dialog among people who ostensibly spent years being inducted into a common contextual foundation.

Post-web journalism and open access publishing might be challenging that tradition, but the answer is probably not to staple an introductory textbook to every paper.

Then all scientific papers would be thousands of pages long.

Ahh, the dangers of writing a comment whilst distracted. I meant rather to include the context you need to have yourself; something akin to "you must be this tall to ride", "you need a doctorate in physics to have a chance of understanding this properly".

Studying the positions movements of single molecules in a fluid is near-impossible; increasingly (as we've eaten all of the low-hanging fruit), more science is being done through simulation. Certainly, we should vet those simulations very carefully (as should we more direct experiments). But they're just another tool to understanding the world.

Computer simulations are not nothing either.

> The team expect that the model they have devised will pave the way for new experiments that will validate the theory and extend the concept of ‘entangled’ liquids to other liquids such as silicon.

Yes, they are very useful. Now they have something specific to look for with in experiments.

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