[n4r9]

I may be missing something here, but there's a conceptual leap from "the acceleration produced by gravitational force" to "gravity as a form of acceleration".

Da Vinci certainly appears to be exploring the former. The latter was Einstein's great insight. I don't see much in the article to persuade me that da Vinci was equating gravity and acceleration in the way Einstein did, and so the title seems a little too suggestive.

[mannykannot]

Indeed; this seems to be an extreme example of what might be called the "whig history of science", which interprets the past in the light of what we know today, attributing, to historical figures, modern concepts which they surely never even conceived of, and which would undoubtedly baffle them until they had been brought up-to-date with current knowledge.

https://en.wikipedia.org/wiki/Whig_history

[valvar]

> attributing, to historical figures, modern concepts which they surely never even conceived of, and which would undoubtedly baffle them until they had been brought up-to-date with current knowledge.

I don't think that's quite what Whig history is. The Wikipedia article doesn't seem to imply that, either. If there was a "Tory history", I think this case would be more like that, as it presents a past figure as being more enlightened (while Whig history typically does the opposite in order to extol progress).

[mannykannot]

Yeah, I'm not certain about the analogy, and I'm basing it more on how I have seen the phrase used in other places, but my cursory search did not dig them up. IIRC, the complaint is that, in order to present history as the steady progress towards what they regarded as an enlightened present, Whig historians attributed influential and powerful historical figures with liberal motives and goals. Tory historians might have attributed them with illiberal motives and goals that were sometimes thwarted (leading to what they regarded as a suboptimal present), which might well be more plausible in general.

Looking a little further into the article, I see it mentions a whig history of science that ignores failed theories and dead ends, and I would agree that this is not the same as attributing successful theories to people who probably did not hold them, though the latter does also tend to present science in 'march of progress' terms.

[lucideer]

You're right but upon reading the article it does seem to actually be a form of Whig history - the article attributes the actual first work on this to Galileo (not Einstein), so while the headline is misleading, the article content seems to simply be surprised someone in the 14th century could be aware that gravity causes objects to accelerate at all.

The idea that the Galileo in being the first to formalise an equation for precise calculation of acceleration was by extension the first in history to conceptualise that acceleration occurs at all is a severe infantalisation of all scientists who preceded him.

[syntaxfree]

A conservative history would emphasize more the contingency of the scientific process and the fact that it wasn’t inevitable that we’d get where we got.

Extending this: the Whig story on contemporary science (sp. as it affects policy) is that this is the best science because scientists have been improving it forever, while the conservative story is that maybe the scientists are wrong now, they’ve so often been wrong in the past.

[poiuyt098]

https://en.wikipedia.org/wiki/Precursorism

states it more clearly

"... a characteristic of that kind of historical writing in which the author seeks antecedents of present-day institutions or ideas in earlier historical periods. This kind of anachronism is considered to be a form of Whig history ..."

[dragonwriter]

Except in the rare case where a new idea emerges and is introduced fully formed in its final stage, there are precursors of present-day institutions and ideas in earlier historical periods so seeking them would just be normal history.

[mannykannot]

That's true in general, but that is not what seems to be the case here, and the full article on precursorism linked by poiuyt098 suggests that correct usage would be confined to such cases.

[n4r9]

Like the other reply I question whether this is an example of what's in your wiki article. However I have often wondered why something like Democritus' atomic model of the universe is given such praise when it probably had very little going for it at the time, and now I know the terminology for this phenomenon, so I am grateful for that :)

[samstave]

I call BS on this particular account of a Vinci ;;

He was millennia ahead of his time, and I personally believe he had an understanding of physics but was existing in a time where the tools available to his understanding were what was lacking.

This guy predicted eddy-based hydrodynamic in the cardio vascular system before "human biology" was considered a science.

Look at da vinci's designs for the eddy-hydro-pump system...

Maybe he was a time traveling engineer who needed to plant seeds of knowledge in our past on this timeline to ensure advancement and growth of Humanity.

[mkl]

> He was millennia ahead of his time

That seems extremely unlikely, but we won't find out for at least 1500 years.

[vhasus]

TIL: thank you

[photochemsyn]

Someone has already incorporated this into the wiki entry for historical development of gravitational theory, which may or may not be entirely justified:

https://en.wikipedia.org/wiki/History_of_gravitational_theor...

That's an interesting article, including some challenges to Aristotle's views and gravity-related concepts introduced by Indian and Islamic scholars of the 6th - 12th century eras or so.

[wolverine876]

> Someone has already incorporated this into the wiki entry for historical development of gravitational theory, which may or may not be entirely justified: > https://en.wikipedia.org/wiki/History_of_gravitational_theor...

Isn't that a core problem with Wikipedia? I don't understand why its reputation on HN improved, a few years ago, from 'infotainment but a symbol of mis-/disinformation' to 'source of truth'.

[red_trumpet]

Well, thinking of gravity as a force is Newtonian mechanics, which was also not available to da Vinci.

[globuous]

Which was in itself the genius of this newton guy. It’s one thing to realise that objects falling accelerate. It’s another to realise that F=ma, and that this can model objects falling as well as a bunch of other things. Surely da Vinci wasn’t lucky enough to have an apple fall on his head ? :)

[codethief]

> "gravity as a form of acceleration". […] The latter was Einstein's great insight. […] equating gravity and acceleration in the way Einstein did

This sounds like a gross misinterpretation of what Einstein said.

Einstein's great insight was that gravity defines inertial (i.e. non-accelerated) frames of reference. Put differently, in free fall you are not in an accelerated frame, despite what an outside observer on the surface of Earth might say. This is commonly abbreviated by "All massive bodies follow the same (inertial) trajectories in the presence of gravity, irrespective of their constitution", which is the Equivalence Principle.

What you are maybe referring to is what an observer experiences who stands still on the surface of a massive body: They can't free-fall, and so they're not in an inertial frame (= the thing defined by gravity) and thus actually accelerate upwards from the point of view of spacetime.

[n4r9]

I'm probably missing some of the nuances, but I'm referring generally to the Equivalence Principle, described by Einstein as:

> we ... assume the complete physical equivalence of a gravitational field and a corresponding acceleration of the reference system

[codethief]

I see. Personally, the way I have always interpreted that quote is that here, in this particular case, "gravitational field" is supposed to mean "someone standing on the surface of Earth, experiencing gravity" or, more generally, "an observer in a spacetime who's not in free fall / not moving along a geodesic" (but e.g. standing on the surface of a massive body).

Otherwise, as outlined in my previous comment, it does not make any sense.

[coldtea]

>I don't see much in the article to persuade me that da Vinci was equating gravity and acceleration in the way Einstein did

Thinking of the effect on speed of things falling down as acceleration (as opposed to constant), and even coming up with a formula, is already a bridge between these two things.

[Gregaros]

No, it is not at all a bridge to Einstein’s ‘gravity and acceleration are equal’, which is "the gravitational force is physically indistinguishable from any acceleration", which has to do with changing to relatively accelerating reference frames.

The insight of da Vinci’s here is anticipating Newton, not Einstein. And yes, this is already an accomplishment, but not the outlandish one the article would imply.

[coldtea]

Hence "a bridge". It's not Einstein's result, but it's moving towards Netwon (and eventually that) from older ideas about the behavior of things "falling" (such as proportional to their weight and constant speed).

[lamontcg]

Yeah, this is just high school Newtonian physics where we should have all learned the concept of gravitational acceleration.

[razor_router]

agreed, there's no evidence is there that suggests Da Vinci was equating gravity and acceleration in a similar way to Einstein

[hummus_bae]

Early on in my physics career, my supervisor asked me to keep in mind “it’s about speed, not velocity” when doing calculations. In general a force is a change in momentum, i.e. a change in speed. Acceleration is a change in speed relative to some frame. It’s quite possible that da Vinci may unknowingly have seen gravity as an acceleration (as in my example above) and taken the next step to seeing it as a change in speed.