Talk:Isaac Newton/Archive 10

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"Age of the Earth"

Currently, the article claims at two points that "[Newton] was also the first to calculate the age of Earth by experiment". This claim cites "Newton's Contribution to the Science of Heat", which does claim that Newton did this, but confusingly only provides a citation that Newton once calculated "how long it would take a red-hot ball of iron the size of Earth to cool" (for which Newton derives a timeframe of at least 50,000 years).

Following this back, the specific verbiage used in the article cites to the 1846 translation of the Principia Mathematica, specifically in this section. However, this section notably doesn't feature Newton calculating the age of the Earth. He brings up a hypothetical ball of hot iron to demonstrate a point about the heat and age of a comet, not to measure the age of the actual terrestrial planet. This seems to be misinformation based on a misreading of a particular section of text. Joshless128 (talk) 04:47, 21 August 2025 (UTC)

In the passage cited, Newton explicitly compares a hypothetical globe of red-hot iron to the Earth, stating that "a globe of red hot iron equal to our earth... would scarcely cool in an equal number of days, or in above 50000 years." This statement seems to clearly indicate that he is making a comparative calculation regarding the cooling time of such a globe, which can be interpreted as a method for estimating the age of the Earth based on experimental reasoning. This aligns with what Simms was stating in regards to Newton being the first to attempt to calculate the age of the Earth. By mentioning Earth as a comparative object for the globe, Newton effectively scaled up his findings to provide an age estimate. Reaper1945 (talk) 16:15, 31 August 2025 (UTC)

When Newton uses the word "equal", he's plainly discussing its diameter/surface area. You wouldn't need to make such a comparison if you were talking about the Earth itself, as you would just say "Our Earth took [such and such] years to cool, based on these calculations".

In either case, it's clear that the calculation doesn't apply to Earth based on the fact that the principal assumption behind it is that it's a "red-hot ball of iron". Earth is not made of iron, nor did Newton have any reason to assume the ball was red-hot. It only serves as a function for a calculation of Earth's age as much as "the time it takes the Sun to emit 10^24 kg of hydrogen" serves as one. Joshless128 (talk) 18:33, 31 August 2025 (UTC)

I take your point that Newton’s immediate purpose in the Principia was to illustrate cometary heat retention, and that the “red-hot globe of iron” is a hypothetical construct rather than a literal description of Earth. However, as Simms pointed out, Newton explicitly scaled his cooling-law experiment to a globe “equal to our Earth,” concluding it would take at least 50,000 years to cool. Simms describes this as “the first attempt to determine the age of the Earth by experiment,” an interpretation also cited by Rowlands in Newton and the Great World System. The fact that Newton chose to scale the calculation specifically to Earth suggests that he regarded the comparison as meaningful in that context. Pask (2013) further notes that this line of reasoning directly foreshadows Lord Kelvin’s later method of calculating an age for Earth from thermal cooling. Reaper1945 (talk) 19:41, 31 August 2025 (UTC)

I don't think Newton regarded the information as meaningful, as in general it seems likely that Newton believed in a ~6000 year old Earth based on Biblical calculations (as with many of his contemporaries). I think the "meaning" of the calculation was solely to demonstrate a range of numbers for the cooling of various objects. Ex., I don't think Newton literally believed there to be "an inch diameter" red hot orb of iron somewhere, as he calculates directly before this line.

Again, though, the Earth is not a ball of iron, something Newton was surely aware of. The calculation doesn't serve as a calculation of the age of the Earth based just on that information, much less any other. It doesn't seem likely that Newton intended it to be seen this way, nor does it fit the science of the time, nor does it even really make sense as a series of assumptions for anyone to make. Joshless128 (talk) 20:19, 31 August 2025 (UTC)

I appreciate the perspective, but I think we need to be careful not to substitute our own interpretations of Newton’s beliefs, we need to rely on what reliable secondary sources actually say or interpret his work, not how we view it as such. Whether Newton personally believed in a ~6000-year-old Earth, or whether he thought of the “red-hot globe of iron” as a purely illustrative construct, is ultimately less important than how historians or academics have interpreted his words.

As stated, Simms explicitly describes this passage as “the first attempt to determine the age of the Earth by experiment,” and Rowlands cites this interpretation as well in his own work. Colin Pask (2013, p. 457) even views Newton's hot globe hypothetical in the same way as Simms, stating that Newton "tossed out one of his stunning asides: he suggested a way to calculate the age of the Earth… About 150 years later, Lord Kelvin was following Newton and calculating an age for the Earth by modeling its cooling processes." These are reliable secondary sources that interpret Newton’s comparison to Earth as meaningful in the history of attempts to date the planet. Do you have any reliable secondary sources that oppose the interpretation of Simms or Pask? Reaper1945 (talk) 20:30, 31 August 2025 (UTC)

I think that's a ludicrously high standard of evidence. I don't think there's a "reliable secondary source opposing this" because very few people know about the line in the first place. I also think you're kinda just burying your head in the sand.

Newton's calculation is not a calculation of the age of the Earth, period. It's a calculation of the cooling time for a hypothetical ball of iron. There is no evidence he interpreted this as the age of the Earth proper. Nowhere does he state this belief. Nowhere is this belief espoused in the text itself. It's no more a calculation of the age of the Earth than "the time it would take a cow to grow to the mass of the Earth" is one. I don't think people tossing it out as a fun fact in the middle of otherwise completely unrelated articles is a serious piece of evidence either. If you want, I could literally just email the authors and ask them to retract the claims, but if not I'll probably just remove the source. Joshless128 (talk) 20:38, 31 August 2025 (UTC)

Wikipedia does not determine content based on what editors personally find plausible or “common sense.” The passage in question has been interpreted by multiple reliable secondary sources — Simms, Rowlands, and Pask — as the first experimental attempt to estimate the age of the Earth. Whether or not Newton personally believed this, or explicitly stated it as such, is not relevant; what matters on Wikipedia is what reliable sources say. Unless there is a published source that directly disputes Simms or Pask, removing or challenging these citations would constitute original research, which is against Wikipedia policy (WP:NOR, WP:V). We go by reliable secondary sources, you have not provided a single one and are being belligerent without reason. I'm sure the authors will retract their statements simply because a user on a website disagrees with them.Reaper1945 (talk) 20:47, 31 August 2025 (UTC)

Whatever dude, I think you're being obstinate. I've gone ahead and emailed them because this is fairly cut-and-dry and I think you're exploiting rules beyond their intent. If a "secondary source" claimed Aristotle predicted quantum mechanics because he said "sometimes things happen one way and sometimes they happen a different way" this would be obvious nonsense for the same reason. Joshless128 (talk) 20:51, 31 August 2025 (UTC)

The interpretation of Newton’s “red-hot globe” calculation as an early experimental attempt to estimate Earth’s age is supported by multiple reliable secondary sources (Simms 2004; Rowlands, Newton and the Great World System; Pask 2013). Wikipedia policy requires that content reflects what reliable sources say, not personal interpretations of Newton’s intent (WP:V, WP:NOR). If a reliable secondary source exists that contradicts this interpretation, it can be added to the article; until then, the sources cited are appropriate for inclusion. I'm going off of what the secondary sources say, as Wikipedia requires, sorry, I don't go off what I believe personally, as again, that's original research. Reaper1945 (talk) 20:54, 31 August 2025 (UTC)

Whatever you say. Joshless128 (talk) 20:59, 31 August 2025 (UTC)

Cat Door Myth

There is a common urban myth regarding Isaac Newton's supposed invention of the cat door.

This has already been well elaborated on in the Wikipedia article on the pet door and briefly brought up in the Wikipedia article on Isaac Newton in pop culture, but perhaps the main article on Newton could benefit from a mention of it in the legacy section or maybe even the implementation of a legacy subsection covering the myth?

Just a charming idea for extending this article's description of Newton's cultural legacy :) And I suppose also to clarify that this somewhat popular legend is (much like the apple hitting Newton's head) not exactly a historical fact.

I'm eager to hearing anyone else's thoughts on my proposal. After all, I'm not 100% confident that this would be a worthy addition to the article.

Kind regards, Xyqorophibian (talk) 12:25, 25 October 2025 (UTC)

Sorry I don't agree. The sources in Pet_door#History are not clearly reliable and they only speculate. Johnjbarton (talk) 15:58, 25 October 2025 (UTC)

Hi @Johnjbarton.

Yeah, sources aren't really optimal, but this is about nothing more than a common myth.

Would clarifying that there's little verifiable information surrounding the myth (or simply just stating the presence of the myth rather than delving into foggy details) make it a more appropriate addition?

Or is it just not really worth it?

Response much appreciated, Xyqorophibian (talk) 22:07, 25 October 2025 (UTC)

In my opinion the sources don't say it's a myth. Rather we have one anonymous story, one report on a door, and two biographers who say he did not have a cat. One of these biographers calls it a "trivial fiction". It will only become a myth if we repeat the fiction. Johnjbarton (talk) 22:42, 25 October 2025 (UTC)

Hi @Johnjbarton.

Yes, I probably should've used the term apocryphal or anecdote rather than myth.

You've got a fair point about not amplifying "trivial fiction".

That said, I wonder if it could still be implemented in a manner that doesn't mislead readers on its reliability and/or verifiability.

Kind regards, Xyqorophibian (talk) 22:52, 25 October 2025 (UTC)

Autism

The article says that Newton is not considered to have been autistic. It cites a 2017 book.

I see:

• "Other notable figures who may have had an autistic condition include Albert Einstein, Sir Isaac Newton and Henry Cavendish."
• "For instance, notable figures such as Albert Einstein, Isaac Newton, W.A. Mozart, and others, presumed to have been autistic..."
• "Also, Isaac Newton was among those who showed such [autistic] symptoms.  He would talk little; he could get so absorbed in his work that he would even forget to eat; he had few friends, and he would often behave in an indifference or quarrelsome manner even with them."
• All of chapter 3 in this book
• "Consider...the speculation that many individuals who would meet present-day criteria were previously mis- or undiagnosed, including some of the most accomplished, albeit idiosyncract, historical figures, such as Isaac Newton..."
• "Several well-known 'geniuses', such as Albert Einstein and Isaac Newton, are believed to have had autism."

and so forth. I didn't see a single source saying that he didn't have autism, and I only saw one that said there is only evidence of "elevated autistic traits" and not enough information to justify a posthumous diagnosis.

I therefore believe that the statement that he's not considered autistic is factually wrong (not merely WP:UNDUE), and therefore I have removed it. I think it would be WP:DUE to mention the apparently widespread viewpoint that he may have been autistic. WhatamIdoing (talk) 02:25, 27 October 2025 (UTC)

Yup, there are various diagnoses, such as paranoid schizophrenia or psychosis due to mercury intoxication. tgeorgescu (talk) 02:27, 27 October 2025 (UTC)

The book that spends a chapter on him suggests that he had both autism and bipolar.

However, my search for schizophrenia claims largely found self-published and otherwise unreliable sources. Reliable sources tended to say only that he "became psychotic at age 51", or "would probably be called schizotypal" without claiming schizophrenia. WhatamIdoing (talk) 02:46, 27 October 2025 (UTC)

There is a scholarly source by doctor Milo Keynes arguing against diagnosing Newton with something such as Asperger's syndrome. It is too easy to cherrypick certain peculiarities out of his life and brand it as a type of autism. The behaviors exhibited aren't exclusive to the disorder, and his distrust, low self-esteem, and social isolation have been argued to stem from maternal deprivation during childhood. Keynes also points out that Newton had extremely capable manual dexterity and technical ability, variety of intellectual interests, and was highly competent as a civil servant, unlikely for someone with the disorder. Reaper1945 (talk) 04:09, 27 October 2025 (UTC)

Dyspraxia affects some but by no means all people with autism, and any time spent contemplating autism rates in Silicon Valley should convince you that technical ability is not at all incompatible with autism. I have read that an Autistic special interest in high IQ adults tends to change focus over time.

That looks like it would be a good paper to cite if we wanted to say something like "Some sources think he was autistic, and others do not". WhatamIdoing (talk) 05:47, 27 October 2025 (UTC)

Something along the lines of a disagreement over what he may have had would work, some peculiar qualities he had point toward this disorder, while others qualities (such as noted in the paper), say otherwise. Reaper1945 (talk) 23:19, 27 October 2025 (UTC)

I'd include examples only if we want to dedicate that much space to it. I'm not sure that it's worth more than a statement that views are divided. WhatamIdoing (talk) 02:20, 28 October 2025 (UTC)

I agree with a minimal statement and Keynes source, maybe Ioan Mackenzie James as secondary as he mentions multiple sources going different direction. Johnjbarton (talk) 02:35, 28 October 2025 (UTC)

Semi-protected edit request on 21 December 2025

Change Newtons alchemy section from only focusing on to focus more on cover up of his alchemy work. Newton was seen as a symbol of pure reason and alchemy was heretical at the time so his work on alchemy was hidden for many years. https://www.pbs.org/wgbh/nova/article/newton-alchemist-newman/ Aadler7122 (talk) 20:38, 21 December 2025 (UTC)

 Not done: it's not clear what changes you want made. Please detail the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Day Creature (talk) 21:27, 21 December 2025 (UTC)

The article discusses Newton's work in alchemy in numerous places. The NOVA source is fine, but I don't what it adds to his bio. It does not say the work was heretical at the time, it only says that it was newly legalized and practiced by numerous other famous scientists from that time. It does say his work on alchemy was covered up after he died because times had changed and alchemy was "useless medieval knowledge". But these are facts about Alchemy, not about Newton. Johnjbarton (talk) 23:32, 21 December 2025 (UTC)

"Apple Incident"

Why does the Article say "Apple Incident"? It wasn't something bad that happened. It was just an Apple. ~2025-36469-84 (talk) 01:41, 23 December 2025 (UTC)

I changed it to "Apple story" Johnjbarton (talk) 03:02, 23 December 2025 (UTC)

I found at least one source Isaac Newton: Who He Was, Why Apples Are Falling (National Geographic) that refers to it as a "legend." Could "Apple legend" be a better word choice? GeogSage ^{(⚔Chat?⚔)} 08:50, 23 December 2025 (UTC)

I think the section makes a strong case that Newton told this story repeatedly. We don't have video of the apple falling but we have multiple people at the time relating the same story. The biggest issue with the story is its meaning. Some tellings have Newton "discovering gravity" by seeing the apple fall, which is just silly. From what I have read, Newton used the falling apple to illustrate the puzzling fact that objects fall downwards on Earth while planets do not. So the apple story could just as well be viewed as Newton's discovery of a simple to explain example of terrestrial gravitation. But the story itself was not made up after Newton's death and thus is not a legend in my opinion. Johnjbarton (talk) 16:59, 23 December 2025 (UTC)

A "legend" does not have to be untrue. Per the article, "A legend is a genre of folklore that consists of a narrative featuring human actions, believed or perceived to have taken place in human history" and "Many legends operate within the realm of uncertainty, never being entirely believed by the participants, but also never being resolutely doubted. Legends are sometimes distinguished from myths in that they concern human beings as the main characters and do not necessarily have supernatural origins, and sometimes in that they have some sort of historical basis whereas myths generally do not." From my understanding of the word, this story seems to fit the definition. GeogSage ^{(⚔Chat?⚔)} 19:08, 23 December 2025 (UTC)

The value of money in Newton’s day?

The article says £20,000 was worth £4.4 million in 2020, then shortly after says £30,000 is worth almost £1 billion in “today’s money.” Obviously both cannot be true, so which one is it? The former certainly sounds more plausible. Galagora (talk) 00:08, 8 January 2026 (UTC)

By their own terms, both are correct - the issue is that there isn't just one way to compare historic currency values. Measuring Worth is a good resource on the different options.

The £30k = £1bn sum references a Financial Times article which says it is "indexing to GDP rather than CPI" - i.e. it is calculating what share of the country's GDP Newton owned, and comparing that to the same share of GDP now. By that maths, £30k does indeed work out to around £1bn. Whereas the other comparison is using CPI - comparing wealth to the value of a bundle of household goods - which gives the lowest of the various equivalents. Comparing to average wages, or to per capita GDP, gives results in between.

I agree we should be consistent, though - probably most sensible is simply to use Template:Inflation which by default uses RPI. TSP (talk) 01:44, 8 January 2026 (UTC)

The Ocean of Truth

We read "Despite his known preference of a particle theory, Newton noted that light had both particle-like and wave-like properties in Opticks, and was the first to attempt to reconcile the two theories, thereby anticipating later developments of wave-particle duality, which is the modern understanding of light. The physicist David Finkelstein called Newton 'the first quantum physicist' as a result."

This is not a mainstream view; most physicists and historians of physicists would trace the origin of quantum theory to Max Planck in 1900.

There are many quotes under Legacy, e. g "The mathematician and physicist Joseph-Louis Lagrange called Principia 'the greatest production of the human mind', and noted that 'he felt dazed at such an illustration of what man's intellect might be capable'". Fine stuff, but doesn't it go on rather long?

I do propose adding the following: Wordsworth's description of Newton's statue at Cambridge: "The marble index of a mind forever/ Voyaging through strange seas of thought, alone." (It's a famous line, and rounds out the Alexander Pope quote that starts the section.)

And the following, from Newton himself: "I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me." Charlie Faust (talk) 23:10, 11 February 2026 (UTC)

• Despite his known preference of a particle theory, Newton noted that light had both particle-like and wave-like properties in Opticks, and was the first to attempt to reconcile the two theories, thereby anticipating later developments of wave-particle duality, which is the modern understanding of light.

sourced to

• Bacciagaluppi, Guido; Valentini, Antony (2009). Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference. Cambridge University Press. pp. 31–32. ISBN 978-0-521-81421-8. OCLC 227191829.

This source seems only to have a footnote on the topic.

• Arianrhod, Robyn (2012). Seduced by Logic: Émilie Du Châtelet, Mary Somerville and the Newtonian Revolution. New York: Oxford University Press. p. 232, 315. ISBN 978-0-19-993161-3.

This source discusses Newton in relation to De Broglie-Bohm theory, not wave particle duality.

I agree that this claim is extraordinary and not supported by appropriate sources. Johnjbarton (talk) 23:54, 11 February 2026 (UTC)

Thank you. Certainly scientists stand on the shoulders of giants, and every subsequent physicist stood on Newton's shoulders. But quanta came in 1900, with Planck. Einstein applied it to light in 1905, and Bohr to the atom in 1913. de Broglie's wave theory was in 1924. All long after Newton, who was a solidly classical physicist.

Extraordinary claims require extraordinary evidence, and this one is not. Charlie Faust (talk) 00:19, 12 February 2026 (UTC)

I agree that quantum theory in the modern sense begins with Planck in 1900, and the paragraph was not meant to propose that Newton be presented as originating quantum mechanics. The intention of the sentence was more limited: to reflect that some historians of physics have noted that Newton attributed both corpuscular and wave-like properties to light and attempted to account for interference and diffraction using both aspects. For example, Bacciagaluppi and Valentini write that" In the case of light, then, the idea of combining both particle-like and wave-like aspects was an old one, going back indeed to Newton". Similarly Arianrhod notes that "Newton had been the only one to entertain the idea that light behaved like both a wave and a particle." Both sources emphasize that Newton considered light to exhibit both particle-like and wave-like behavior, a combination that would later reappear in dual-aspect or pilot-wave theories. In line with this interpretation, Finkelstein described Newton as "the first quantum physicist," as an interpretation of Newton's efforts. Reaper1945 (talk) 03:40, 12 February 2026 (UTC)

Yes, Christiaan Huygens proposed the wave theory and Newton the corpuscular theory. But neither was a quantum physicist. Both certainly influenced subsequent physicists, but calling Newton "the first quantum physicist" is confusing in an article for general readers. Charlie Faust (talk) 03:54, 12 February 2026 (UTC)

I agree that neither Newton nor Huygens were quantum physicists in the modern sense, and the article does not state that. The text was meant to carefully attribute the statement directly to Finkelstein in a matter such as that: "In line with this interpretation, Finkelstein described Newton as 'the first quantum physicist,' as an interpretation of Newton’s efforts." The phrasing is meant to convey that this is Finkelstein’s commentary on Newton specifically, rather than a claim that Newton literally was a quantum physicist or that he founded quantum theory. Reaper1945 (talk) 03:58, 12 February 2026 (UTC)

Fair point, but it's unnecessary in an article on Newton for the general reader. In an article on the history of wave/particle duality, it would be worth noting that Newton had an inkling of the idea. But associating Newton with developments that took place long after his death is unnecessary, and potentially confusing. Charlie Faust (talk) 04:09, 12 February 2026 (UTC)

True and I agree, the article is about Newton, not the history of wave–particle duality. The phrasing "anticipating later developments" was meant to reflect the interpretations of the sources (Bacciagaluppi & Valentini, Arianrhod, Finkelstein) without asserting it as fact. It reports that some scholars see Newton’s consideration of both particle- and wave-like behavior as a conceptual precursor to ideas that emerged much later, rather than actually suggesting he directly contributed to quantum mechanics. The Finkelstein quote was just an acknowledgement of how some academics may view Newton's work in retrospect. Reaper1945 (talk) 04:23, 12 February 2026 (UTC)

References