And, in the last paragraph of the general scholium, the appendix of the Principia, Newton describes electromagnetism and the role of electrical oscillation in the nervous system. It’s actually the root of the the history of “vibes”
“And now we might add something concerning a certain most subtle Spirit, which pervades and lies hid in all gross bodies; by the force and action of which Spirit, the particles of bodies mutually attract one another at near distances, and cohere, if contiguous; and electric bodies operate to greater distances, as well repelling as attracting the neighbouring corpuscles; and light is emitted, reflected, refracted, inflected, and heats bodies; and all sensation is excited, and the members of animal bodies move at the command of the will, namely, by the vibrations of this Spirit, mutually propagated along the solid filaments of the nerves, from the outward organs of sense to the brain, and from the brain into the muscles. But these are things that cannot be explain'd in few words, nor are we furnish'd with that sufficiency of experiments which is required to an accurate determination and demonstration of the laws by which this electric and elastic spirit operates.”
https://web.archive.org/web/20100524103006/http://www.isaacn...
potamic · 2h ago
This is some remarkable intuition. Electromagnetism wasn't even developed as a theory. To observe such varied phenomena like how nerves communicate or what comprises matter or the behaviour of light and postulate they might all have something in common and something to do with the attraction/repulsion seen when objects are rubbed together, is incredible. Was the idea very unique for its time or did scientists at the time hold similar ideas? Do you think it was just a lucky guess in the end that the world didn't turn out to be more complex or was there some reason behind this craziness?
bonoboTP · 49m ago
It's tricky in hindsight. He also guessed stuff wrong, and how the biology eventually turned out is not exactly how he imagied. You project a modern understanding on that text but you don't really understand the significance of the phrasing he uses, such as spirit etc. It's a loose match, perhaps better than Democritus and the atom, but still needs hindsight bias.
People had similar theories, like Descartes imagined nerve tubes carrying fluid to act and kind of hydraulic actuation, as well as ancient Greek pneuma theory of vital spirit. Gilbert's work on magnetism and electricity was known, Hooke's work on vibrations.
It's impressive of course but now out of this world unimaginable magic. He plugged his favorite modern theory to biology, replacing the fluid stuff with electric stuff. Tons of people did that kind of thing before and after, sometimes it works, sometimes it leads to nowhere.
dr_dshiv · 1h ago
Agreed, it’s astonishing intuition. It’s hard to call it a lucky guess when it is the last paragraph of Newton’s magnum opus. But very hard to explain.
Choosing my words carefully, I think it was a kind of deep and deliberate magic. Of the sort Newton ascribed to Pythagoras as the esoteric discoverer of the inverse square law of gravitation. (see “Newton and the pipes of pan”). Hooke also had a sort of musical, oscillatory, spiraling conception of mental phenomena. So it was in the Zeitgeist.
In any case, it is striking and amazing— and resonant in this age of vibes.
dotancohen · 1h ago
People like Newton, in earlier eras, would be called prophets. And Newton wasn't do far from the religious aspect himself. He was considered crazy in his time, disliked by most. He was an adherent of the occult, in fact he discovered gravity while specifically looking for ways to move objects from afar. Oh, he found it. Today he is revered, and rightly so, but at the time he was hated though he was respected.
bonoboTP · 43m ago
I don't think prophet is the right word. Prophets didn't develop physics or engineering but warned the tribe of God's impending punishment unless they obey better or similar historic predictions of how God will use floods or draughts or enemy tribes to challenge you etc.
throwaway843 · 1h ago
The world was very pious then. To have written that paragraph a century earlier may have resulted in ostracizm. To have written it like that was enough given the limited backing that ould be given. It was enough to influence those around and after Newton, it was, in that sense, remarkable.
eirikbakke · 33m ago
This must be the mother of all "This is left for future work" paragraphs.
windowshopping · 2h ago
> It’s actually the root of the the history of “vibes”
?
dr_dshiv · 1h ago
Yeah, so I’m working on a piece about this. Of course, “cosmic sympathy” and “harmony of the cosmos” goes back to the stoics and Pythagoreans. The direct use of the term vibration in the context of mental activity (“thought vibrations”) is from the American New Thought Movement and Theosophy — that’s where The Beach Boys got it from. But it extends back over the centuries to Newton and then Willis (who used sympathetic vibrations as the basis of his introduction of associationism in psychology).
NoToP · 3h ago
I had no idea Newton also pioneered British understatement.
progre · 4h ago
To me, the funniest part of why Principica was bankrolled by Edmund Halley is that is was supposed to be funded by the Royal Academy. Only, their previous publishing project "The history of fishes" had faceplanted and they had no money.
Also, when Principica was funded and Halley was himself short on cash, RA decided that they could not afford to actually pay him money (he was the RA secretary). Instead he would get copies of The History of fishes
perihelions · 2h ago
I enjoyed this anecdote. As gratitude, please accept this copy of History of Fishes
wait! wait!
so you are saying that there is an official exchange rate for fish books to pounds strerling, guinies?
all I can say is that hopefully someone keeps a copy of the fish book next to a copy of the Principica as a demonstration/proof of the vast leap and gap that suddenly occured
dotancohen · 1h ago
Or as an example of he who gets the funds, not necessarily being the worthy of the two.
Many in academia might like to remember this example.
d4rkn0d3z · 39m ago
For the record, Newton was vastly conceptually wrong which is not the same as saying his work is useless because being wrong in a precise way is science. Time does not "flow immutably from one moment to the next" and there are no gravitational "forces" acting magically at a distance. Even if the linear approximatiins he made hold on a narrow domain they offer little in the way of conceptual framework. In fact, mostly Newton played mathematical parlour tricks.
If you are waiting for science to tell you "why" things hapoen you will wait forever because science answers "how" things happen.
There is no way for a successor scientific theory to completely subsume all of the predictions of its predecessor because they are often incommensurable. Which is to say that there is simply no way to define one in the terms and concepts of the other.
If you think of GR as some extension or modification of Newton's work you're doomed to misunderstanding the mathematical facts.
roenxi · 7h ago
> Halley’s intervention saved science from being reduced to “things fall down because they do” for another century.
Well, that might be stretching it. Speaking as someone who has done a little university level physics the understanding still seems to be basically that things fall because they do - we haven't made much progress beyond a firm strike-through of the word "down".
Newton's contribution was a very precise description of how rapidly they fall, and how we can calculate and understand the direction that things fall in complex multidimensional settings.
dataflow · 2h ago
Oh come on. Things fall down because matter has a property called gravity that attracts other matter, and below us is a giant earth with a lot of matter. And it has more of a net effect on us than any other matter in the universe because gravity scales with distance and mass in that particular way. That's as darn good of an explanation of why we fall down as one could possibly give. "But why does mass have gravity?" Why does Newton have to have all the answers to every other question too? Maybe ask that and someone will answer that question in a few hundred years? He answered your original question, he didn't claim he can answer every subsequent question you think of. It's quite ridiculous to suggest Newton just tautologically concluded "things fall down because they do" just because he doesn't go on and explain the "why" of every sub-question ad infinitum.
2b3a51 · 1h ago
I'd just throw in that this idea of universal gravitation coupled with the laws of motion and dodgy ideas like force and momentum enabled a wide range of phenomena to be described and some predictions to be made that could be compared with observations.
Yes, ideas like 'force' and 'momentum' were a bit dubious but the resulting theory was effective[1] within its domain of applicability.
> That's as darn good of an explanation of why we fall down as one could possibly give
Well, around two hundred years later they found out that it is not a good explanation (which of course in no way diminishes Newton's achievements).
TMEHpodcast · 22m ago
Newton’s physics is still taught and used everywhere because it’s simple and accurate enough for 99% of practical situations. Einstein’s relativity isn’t a better explanation, it just extends it to extreme conditions. NASA still uses Newtonian law to launch rockets.
Micoloth · 3h ago
That’s what i though as well
> Why apples fall, why planets don’t wander off, and why we aren’t all quietly drifting into space every time we sneeze.
Newton didnt really explain the why.. Einstein added something much later, but it might be that really we still don’t have a clue.
All we can do is measure how fast it happens, very precisely
TMEHpodcast · 18m ago
You’re correct. Newton wasn’t proposing a mechanism or deeper cause for gravity; he just described its effects. Einstein did add a “why” of sorts, with general relativity, he reframed gravity not as a force but as the curvature of spacetime caused by mass and energy. That’s closer to a mechanism, but even there we might ask: why does mass curve spacetime? And we don’t have a deeper answer to that.
725686 · 7h ago
Isn't it because of the curvature of spacetime? Not that that means much to a layman, but I think that progress has definitely been made.
adastra22 · 3h ago
Yes, general relativity explains gravity pretty darn well, tying it to the fundamental fabric of causality that makes up the universe. It goes from “it just happens” to “it must happen and there is no other way it could be.”
bravesoul2 · 5h ago
It's funny. We don't float away.
We can never say why. Just produce better and better models.
The whys never end!
DanielVZ · 4h ago
It’s interesting how it’s not turtles all the way down (as I understand it at least). The things you learn of one scale do not completely translate to the next but serve as the “shadow” projected by the next level down the line. And this probably brings up the complexity that lets us exist and perceive. I say probably because who knows what else is going on in the universe.
All this to say who knows if we are ever going to learn the fundamental why if there is one.
noman-land · 7h ago
Doesn't mass bend spacetime (do we know why? No idea) and cause matter to "fall" into the gravity well?
kimixa · 6h ago
Maybe? That's one theory - but what is "spacetime", and what does it mean to "bend", or "fall into" something like that? In many ways we've just given things names as if that suddenly means they're understood.
And even then how can that be measured and proven vs other theories? Is it some other mechanism that simplifies to "close enough" that it measures similarly? We didn't really see the effects of relativity until we got to a sufficient accuracy of measurement, Newtonian mechanics was sufficient to explain things to the accuracy they could reproduce for a very long time.
Einstein couldn't have done anything like what he published if he didn't have evidence from new (at the time) equipment suggesting there was something wrong with the current model. And then testing proposed new models against those same measurements.
hermitcrab · 3h ago
Newton's theory of gravitation did not correctly predict the orbit of Mercury. Einsteins theory of gravitation (General Relativity) does.
silisili · 5h ago
I've always been a bit flummoxed we haven't expanded a ton on this given how long it's been.
I'm not sure if it's wrong or right, and not smart enough to posit much, other than it -feels- wrong. But it wouldn't take a ton to convince me otherwise.
You'd think by now we'd have more supporting evidence of such a concept.
griffzhowl · 1h ago
Do you mean evidence for general relativity? Because there's a lot: gravitational waves, black holes, gravitational redshift, the bending of light by gravity, the expansion (or contraction, depending on density) of the universe, are all new phenomena predicted by GR and experimentally verified
thaumasiotes · 3h ago
> In many ways we've just given things names as if that suddenly means they're understood.
The jargon term for this is "dormitive potency" or, more originally, "dormitive virtue".
I think it’s kinda more that (in 3D with time moving at a constant rate) space “falls” into the gravity well, and matter goes with it. In 4D this looks like spacetime being bent.
raattgift · 40m ago
The "river model" you mean isn't very general, as one eventually becomes interested gravitating systems where there isn't a suitable congruence, e.g. in close binary compact objects. In such systems, one has to add terms analogous to turbulence, frustrating calculability (and the development of relativistic intuition). It also doesn't deal well with tides: for example, Schwarzschild infaller worldlines (even on a body like the moon, where there is no horizon) on widely separated radial trajectories converge in a way that is unlike the confluences of rivers and their tributaries. These models really only assist in understanding a single (spatial) radial line with possibly multiple successive "rafts" of matter bound to it (at different times), and in a set of PG-like coordinates useful for a particular distant observer. From there one symmetrizes: all observers and all radial lines are identical (speherical symmetry) and successive "rafts" all take the same radial line (static spacetime). Without this symmetrization, a black hole is an infinite number of slightly different rivers, and then you might as well solve the equations of motion in the standard way.
For understanding a handful of highly symmetrical systems, it might help a student understand some intuitions about what Killing vector fields and congruences (notably those made by choosing the velocity vector field of a set of geodesics) are, and tends to lead into an investigation of what the shift vector in a 3+1 decomposition represents.
For calculating things like the spherical orbits around or the photon surface of a real black hole like our galaxy's central Sgr A*, the river model seems outright unhelpful. For example, how does a river model help to understand https://duetosymmetry.com/tool/kerr-circular-photon-orbits/ ?
> time moving at a constant rate
This is another way of saying slicing of a Lorentzian (4d) spacetime into non-overlapping spaces organized along an arbitrarily chosen future-directed non-spacelike worldline. That is, this is a 3+1 slicing. We can slice along your worldline, or on that of a neutral hydrogen atom floating in intergalactic space, or on that of a high-energy cosmic ray, or on that of a CMB photon. It's arbitrary, and each can give markedly different spatial slices through the same spacetime (in particular particle counts on slices will differ where the choices of index axes are anywhere accelerated with respect to one another).
When we decompose in this way, and take an <https://en.wikipedia.org/wiki/ADM_formalism> approach, we will tend to think of the shift vector as how we associate a point one one slice (everywhere in space at a coordinate instant in the spacetime) with its successor slice (everywhere in space at the next coordinate instant int he spacetime), which is helpful when spacetimes expand or contract in one or more spatial directions along the arbitrarily chosen time axis.
Is "why" really a meaningful question? These are all models. The best we can do is to show how to derive the phenomenon from the (hopefully simple) rules of our model.
brianpan · 3h ago
I think so. The why can be a powerful and compact way to express the elements of a model, when a model can be applied, and when the model might break down. A complicated model without a WHY might not be easily understood by others. A surprising, new result with a good WHY can point the way to other aspects of the model that might be confirmed or disproved.
Think about how much our understanding of atoms has changed. I think the why is an important part of the development. If you're interested in that topic, how about a 35 min nuclear physics primer from Angela Collier (I love her videos!): https://www.youtube.com/watch?v=osflPlZdF_o
SilasX · 5h ago
It's relative. I operationalize "why is X true?" as "update my worldmodel to the point that X is not surprising". The typical way to do that is to show a more general rule that applies, and which implies X. But yes, you can keep asking the question about the more general rule.
Why do things fall? -> A special case of the general law of gravitation.
Why does reality adhere to the general law of gravitation? A implication of matter distorting the shape of spacetime.
Why is reality such that matter distorts space-time?
thaumasiotes · 3h ago
> Is "why" really a meaningful question?
...of course?
If you want something that won't fall down, your only options are (1) luck into noticing something that already does that, or (2) understand why things fall down, so you can prevent your thing from falling.
tristramb · 1h ago
Back in 1987 I was standing outside Thorns Bookshop in Newcastle upon Tyne.
In its window was a display of books by Professor Paul C. W. Davies.
I was saying to someone beside me that Davies wrote too many books for them to be any good.
Then I turned round and almost bumped into the man himself.
Fortunately he hadn't heard what I'd said and just carried on his way.
He was hurrying to give a lecture at the university commemorating the 300th anniversary of Newton's Principia.
Several years later I was to revise my view of his writings after reading his 'Fifth Miracle' which I enjoyed very much.
"Alleged eyewitness reports of Joseph's levitations are noted to be subject to gross exaggeration, and often written years after his death."
That sounds super reliable. ;0)
"Poisoning due to the consumption of rye bread made from ergot-infected grain was common in Europe in the Middle Ages. It was known to cause convulsion symptoms and hallucinations. British academic John Cornwell has suggested that Joseph had consumed rye bread (see ergot poisoning). According to Cornwell "Here, perhaps, lay the key to his levitations. After sampling his own loaves he evidently believed he was taking off–as did those who partook of his high-octane bake-offs.""
Eilmer of Malmesbury showed a bit more commitment to his flying:
“And now we might add something concerning a certain most subtle Spirit, which pervades and lies hid in all gross bodies; by the force and action of which Spirit, the particles of bodies mutually attract one another at near distances, and cohere, if contiguous; and electric bodies operate to greater distances, as well repelling as attracting the neighbouring corpuscles; and light is emitted, reflected, refracted, inflected, and heats bodies; and all sensation is excited, and the members of animal bodies move at the command of the will, namely, by the vibrations of this Spirit, mutually propagated along the solid filaments of the nerves, from the outward organs of sense to the brain, and from the brain into the muscles. But these are things that cannot be explain'd in few words, nor are we furnish'd with that sufficiency of experiments which is required to an accurate determination and demonstration of the laws by which this electric and elastic spirit operates.” https://web.archive.org/web/20100524103006/http://www.isaacn...
People had similar theories, like Descartes imagined nerve tubes carrying fluid to act and kind of hydraulic actuation, as well as ancient Greek pneuma theory of vital spirit. Gilbert's work on magnetism and electricity was known, Hooke's work on vibrations. It's impressive of course but now out of this world unimaginable magic. He plugged his favorite modern theory to biology, replacing the fluid stuff with electric stuff. Tons of people did that kind of thing before and after, sometimes it works, sometimes it leads to nowhere.
Choosing my words carefully, I think it was a kind of deep and deliberate magic. Of the sort Newton ascribed to Pythagoras as the esoteric discoverer of the inverse square law of gravitation. (see “Newton and the pipes of pan”). Hooke also had a sort of musical, oscillatory, spiraling conception of mental phenomena. So it was in the Zeitgeist.
In any case, it is striking and amazing— and resonant in this age of vibes.
?
Also, when Principica was funded and Halley was himself short on cash, RA decided that they could not afford to actually pay him money (he was the RA secretary). Instead he would get copies of The History of fishes
https://archive.org/details/francisciwillugh00will/page/n321...
Many in academia might like to remember this example.
If you are waiting for science to tell you "why" things hapoen you will wait forever because science answers "how" things happen.
There is no way for a successor scientific theory to completely subsume all of the predictions of its predecessor because they are often incommensurable. Which is to say that there is simply no way to define one in the terms and concepts of the other.
If you think of GR as some extension or modification of Newton's work you're doomed to misunderstanding the mathematical facts.
Well, that might be stretching it. Speaking as someone who has done a little university level physics the understanding still seems to be basically that things fall because they do - we haven't made much progress beyond a firm strike-through of the word "down".
Newton's contribution was a very precise description of how rapidly they fall, and how we can calculate and understand the direction that things fall in complex multidimensional settings.
Yes, ideas like 'force' and 'momentum' were a bit dubious but the resulting theory was effective[1] within its domain of applicability.
[1] https://en.wikipedia.org/wiki/Effective_theory
Well, around two hundred years later they found out that it is not a good explanation (which of course in no way diminishes Newton's achievements).
> Why apples fall, why planets don’t wander off, and why we aren’t all quietly drifting into space every time we sneeze.
Newton didnt really explain the why.. Einstein added something much later, but it might be that really we still don’t have a clue.
All we can do is measure how fast it happens, very precisely
We can never say why. Just produce better and better models.
The whys never end!
All this to say who knows if we are ever going to learn the fundamental why if there is one.
And even then how can that be measured and proven vs other theories? Is it some other mechanism that simplifies to "close enough" that it measures similarly? We didn't really see the effects of relativity until we got to a sufficient accuracy of measurement, Newtonian mechanics was sufficient to explain things to the accuracy they could reproduce for a very long time.
Einstein couldn't have done anything like what he published if he didn't have evidence from new (at the time) equipment suggesting there was something wrong with the current model. And then testing proposed new models against those same measurements.
I'm not sure if it's wrong or right, and not smart enough to posit much, other than it -feels- wrong. But it wouldn't take a ton to convince me otherwise.
You'd think by now we'd have more supporting evidence of such a concept.
The jargon term for this is "dormitive potency" or, more originally, "dormitive virtue".
https://en.wiktionary.org/wiki/dormitive_virtue
For understanding a handful of highly symmetrical systems, it might help a student understand some intuitions about what Killing vector fields and congruences (notably those made by choosing the velocity vector field of a set of geodesics) are, and tends to lead into an investigation of what the shift vector in a 3+1 decomposition represents.
For calculating things like the spherical orbits around or the photon surface of a real black hole like our galaxy's central Sgr A*, the river model seems outright unhelpful. For example, how does a river model help to understand https://duetosymmetry.com/tool/kerr-circular-photon-orbits/ ?
> time moving at a constant rate
This is another way of saying slicing of a Lorentzian (4d) spacetime into non-overlapping spaces organized along an arbitrarily chosen future-directed non-spacelike worldline. That is, this is a 3+1 slicing. We can slice along your worldline, or on that of a neutral hydrogen atom floating in intergalactic space, or on that of a high-energy cosmic ray, or on that of a CMB photon. It's arbitrary, and each can give markedly different spatial slices through the same spacetime (in particular particle counts on slices will differ where the choices of index axes are anywhere accelerated with respect to one another).
When we decompose in this way, and take an <https://en.wikipedia.org/wiki/ADM_formalism> approach, we will tend to think of the shift vector as how we associate a point one one slice (everywhere in space at a coordinate instant in the spacetime) with its successor slice (everywhere in space at the next coordinate instant int he spacetime), which is helpful when spacetimes expand or contract in one or more spatial directions along the arbitrarily chosen time axis.
Braeck & Gron 2012 have a good bit of pedagogy about the river analogy and a fine set of references <https://arxiv.org/abs/1204.0419> and of course point to Hamilton & Lisle 2008, as originators of the analogy <https://arxiv.org/abs/gr-qc/0411060>.
Think about how much our understanding of atoms has changed. I think the why is an important part of the development. If you're interested in that topic, how about a 35 min nuclear physics primer from Angela Collier (I love her videos!): https://www.youtube.com/watch?v=osflPlZdF_o
Why do things fall? -> A special case of the general law of gravitation.
Why does reality adhere to the general law of gravitation? A implication of matter distorting the shape of spacetime.
Why is reality such that matter distorts space-time?
...of course?
If you want something that won't fall down, your only options are (1) luck into noticing something that already does that, or (2) understand why things fall down, so you can prevent your thing from falling.
That sounds super reliable. ;0)
"Poisoning due to the consumption of rye bread made from ergot-infected grain was common in Europe in the Middle Ages. It was known to cause convulsion symptoms and hallucinations. British academic John Cornwell has suggested that Joseph had consumed rye bread (see ergot poisoning). According to Cornwell "Here, perhaps, lay the key to his levitations. After sampling his own loaves he evidently believed he was taking off–as did those who partook of his high-octane bake-offs.""
Eilmer of Malmesbury showed a bit more commitment to his flying:
https://en.m.wikipedia.org/wiki/Eilmer_of_Malmesbury
> Eilmer said he had "forgotten to provide himself with a tail."
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