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:
> Eilmer said he had "forgotten to provide himself with a tail."
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.
“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...
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.
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 not 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.
People just didn’t have the tools to understand this subject at that time.
An ancient Greek philosopher said the matter is made of smallest particles. It doesn't mean he found the concept of atoms as we know.
?
Sure, it's polysemous with "a cultivated expanse of land", but AFAIK there is no popular, problematic pseudoscientific quackery about suggesting our bodies possess rows of oats.
If you are waiting for science to tell you "why" things happen 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.
> vastly conceptually wrong
Only for a useless definition of "wrong". Modeling reality well is an end in itself, and to the extent that model predicts well and "factors" reality cleanly into distinct mechanisms, it is conceptually right. This is all "conceptually right" needs to mean. You can not, as I'm sure you'll agree, even hope to explain the "root cause" of motion and time-evolution. at some point you have to base any theory on some postulate or assumption about why things happen at all. But the point of work like Newton's is to get things right above that level, and he was enormously successful at this.
> mostly Newton played mathematical parlour tricks.
Only for a useless definition of "parlour tricks". The hard part of new ideas (1) is getting to the point where you're posing the right problem and thinking about it the right way. Once you get that right, the predictions (2) hopefully fall out as simple tricks! Then they have to be validated (3) against data—also hard. Newton pulled off all three, the hard parts and the tricks. Not single-handedly, mind you, but almost.
To bring such a big picture into view and fill out its details with credibility was a monumental task. I think of it as akin to evolution developing a new organ system—the genome usually has to find its way down on a very long limb to get there and to be stable enough to stay there. For a species this can happen over many generations, but for a human thinker it is has to happen by imagining and testing many subsequent ideas. Newton did an enormous amount of this on his own, over decades.
> are often incommensurable
Newton being absorbed into relativity is like the one case where they are commensurable. Newton is a clear limiting case! The "ways of thinking" about reality are perhaps not, but nobody (except cranks) is still stuck on Newtonianism at this point.
> as some extension or modification
Obviously it contains new math and new abstractions, as needed to match empirical reality on new data. Its content doesn't extent logically out of Newton, because how could it? The data wasn't there. But the conceptual gesture of devising a mathematical framework which can handle the data is the same one Newton used.
Postscript: philosophy of science folks always like to show up in physics discourse ready to fight various tired, old battles which mostly mattered in the context of the particular ideological dispute of some decade or another. The matter in question is always how to generalize the success of physics by fitting various philsci "models" to the "data" of physics' history. This can be interesting, but they never contribute much to the physics itself, which has always proceeded by its own internally-coherent and immensely-successful logic.
The definition of wrong is given in the second part of the sentence you quote. Newton was usefully wrong in a scientific sense; His theory and ontology of time as immutably flowing from moment to moment is fine for beings in a relatively stable gravitational field but fails miserably anywhere else. GR is a theory that gets time less wrong, but entails completely different ontology wherein "forces" disappear. In your parlance, Newton put time below "that level" when he should have lifted it into that which must be reasoned about physically. This means he was wrong conceptually in taking something as an absolute when it was not so.
'Only for a useless definition of "parlour tricks".'
If you look at Newton's work it amounts to little more than a first order approximations, rules to model linear portions of a nonlinear reality. I think you have a very romantic picture of Newton's work. Don't get me wrong, Newton was a giant in his time he had mastered linear curve fitting and to some extent I think he knew what he was doing and that it would be supplanted. I actually think if Newton stood here today he would disagree with you, side with me and take up GR straight away.
"Newton being absorbed into relativity is like the one case where they are commensurable."
Newton's theory was not absorbed, it was supplanted. One cannot absorb the idea of a "force" into GR. This is precisely what incommensurability means.
"Obviously it contains new math and new abstractions..."
It is not about the data, Newton was wrong because non-euclidian geometry wasn't there,
"Postscript"
I have degrees in electronic engineering and theoretical physics. I graduated number one in my class both times. I am not a philosophy interloper as you point out in your ad-hominid attack.
IF you want to make progress in your understanding of physics you best heed the words and thoughts I have provided.
The point of my argument was to express a "practical" epistemology in which Newton's successes represent exactly what they accomplished, instead of some failure to live up to an ideal "truth", a view which I consider useless and pedantic.
> One cannot absorb the idea of a "force" into GR.
Yeah you can, tho I never learned the specifics. IIRC, a force is a Lagrange multiplier representing a constraint on the extremization of action. When you extremize a joint system (two particles A and B interacting) you just get some exchange of momentum between them and no force appears. But if you extremize just A w.r.t to a known and fixed trajectory of B, B's influence on A appears as an "external force" term. This is actually all "forces" ever were—constraints relating dp_A/dt and dp_B/dt—but this fact is obscured in Newton because we typically think of systems with their external forces factored out, which of course lets us apply useful approximations for gravity, air resistance, friction, etc.
You can certainly do the same operation in GR of isolating a subsystem of a joint system and you will find a "force" term, it has to be there just as a logical consequence of the extremization process. I thought this was well known. Or do you mean "one cannot absorb..." in some other sense?
My mistake tagging you as a philsci person, tho. I regret the error!
I can do no such thing. The idea of a "force" as known to Newton, being "action at a distance" by "mutual attraction", is not at all present in GR.
NASA still uses Newton’s framework today. They strap adventurous humans into enormous cylinders, set off controlled explosions underneath, and fling them into space—because three centuries later, it’s still the best idea we’ve got.”
Someone should tell them about relativity!
NASA does a lot of things.
roenxi•11h ago
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.
725686•11h ago
bravesoul2•10h ago
We can never say why. Just produce better and better models.
The whys never end!
DanielVZ•9h ago
All this to say who knows if we are ever going to learn the fundamental why if there is one.
adastra22•8h ago
layer8•2h ago
adastra22•14m ago
Maybe you are confusing causality for the arrow of time?
noman-land•11h ago
kimixa•10h ago
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.
silisili•9h ago
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•5h ago
thaumasiotes•8h ago
The jargon term for this is "dormitive potency" or, more originally, "dormitive virtue".
https://en.wiktionary.org/wiki/dormitive_virtue
hermitcrab•7h ago
dotancohen•2h ago
taneq•10h ago
raattgift•5h ago
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>.
eternauta3k•10h ago
SilasX•9h ago
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•8h ago
...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.
tralarpa•4h ago
No, it isn't. That sounds strange, right? But here is an explanation what eternauta3k probably meant: In modern physics, there is a kind of consensus that asking “why” has often been inappropriate or even misleading and should be therefore left to philosophers. The real questions are: Does our current model describe all observations? If not, can we find a model that does? And, even better, can that new model make predictions that we can verify?
mensetmanusman•3h ago
brianpan•8h ago
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
Micoloth•8h ago
> 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•4h ago
dataflow•6h ago
2b3a51•6h ago
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
tralarpa•6h ago
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•4h ago
sanderjd•3h ago
To me, the right word for this sentence is clearly "how", not "why".
layer8•3h ago
We’re still trying to figure out why exactly energy distorts spacetime.
[0] https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor