The h Bar

Anonymous

18:00

This paper is somewhat good: arxiv.org/abs/quant-ph/0305025

DanielSank

Oh neat. Dave's thesis. Haven't read it!

Anonymous

Heh. I should try reading up your thesis, once, too. It looks good :) (web.physics.ucsb.edu/~martinisgroup/theses/Sank2014.pdf)

DanielSank

@Blue ehhhhhhh

Anonymous

I don't have much knowledge about hardware aspects of QC though. Trying to pick it up with time

DanielSank

When I re-read it, I feel like I could have cleaned up the prose quite a lot.

@Blue The first chapter of my thesis is intended for people like that.

Anonymous

18:03

Oh, cool :P

Anonymous

Good for me

Shing

Anyone knows where Dyson's thesis about how Feynman derived the Maxwell equations to be found?

Anonymous

@Shing Hmm, it's easily google-able aapt.scitation.org/doi/10.1119/1.16188

Shing

@Blue wow!! I did google it for at least half hour but in vain. Thanks!

no_choice99

@Pieter are you here? Have you ever heard of the Peierls transition?

Shing

18:28

damn, the paper is not free.

Anonymous

@Shing scihub?

Shing

@Blue okay, I will try that. thanks

vzn

@Semiclassical thx for the other links those are great, a longtime fan of woit, a bit )( surprised to hear him defend copenhagen, lol. afaik nature has a similar form "[x] explores [y]" where [x] is the reviewer and [y] is the book (topic) with other book reviews. its a stylistic form not unlike other forms found in pubs like NYT etc. not sure exactly why you object to the baggott epicycles comment, makes sense to me. hes author of 1 of really great books on this topic. (meaning of QM theory)

Semiclassical

Because it suggests that Ptolemy’s model had a large number of epicycles. Which in turn points to the now debunked myth that Ptolemy’s model involved multiple epicycles on each planet

It had one epicycle for each of the seven known bodies in the same system

I do have his book as well, and enjoyed it. So I’m all the more rankled to see him misusing history like that

vzn

@Semiclassical not familiar with the details but afaik there were epicycles built on epicycles. hmmm

Semiclassical

18:41

Noooo

Slereah

Binging with Babish: Skinner's Stew from The Simpsons

►

Skinner's secret vietnam stew

Semiclassical

I thought I linked to the Wiki page on that, woops

vzn

guess youre talking about this en.wikipedia.org/wiki/Deferent_and_epicycle#Bad_science

Semiclassical

Right, along with the “Bad Science” section

vzn

@Semiclassical alas seems close to hairsplitting to me.

Semiclassical

18:44

It’s really not.

More details here: math.nus.edu.sg/aslaksen/teaching/copernicus.html

vzn

> some Arab astronomers introduced epicycles on epicycles...

Semiclassical

Yeah, i wish he had given a citation on that

My impression is that no one doing medieval astronomy in Europe did so and so wasn’t part of the context in which Copernicus was working

vzn

the general theme seems to be that epicycles were not invalid exactly for the reasons people suppose & popsci/ folklore sometimes gets it wrong. ok. but they were thrown away for reason(s). thats the key point. its one of the archetypical examples of a kuhnian paradigm shift. & baggotts basic point is that the model can be deceptive wrt the reality™

Semiclassical

One point to consider on that: if you consider Copernicus ‘s work to have been part of a paradigm shift in that way, you’d have expected him to be getting rid of the epicycles

And that’s really not reflective of reality. If anything, Copernicus’s model was closer mathematically to those Arabic modifications (source: faculty.csbsju.edu/cgearhart/Courses/Honors210/Astro/Equant.pdf)

Slereah

Nothing wrong with epicycles

They're just Fourier series

Semiclassical

18:59

No, but there is something wrong with the idea that the typical medieval astronomer was obsessed with adding more and more epicycles in order to avoid a paradigm shift

To the extent that Copernicus’s model was a shift, it was not one predicated on glaring discrepancies in experimental data.

Slereah

Well you know, it's a pretty odd prospect when you find out something that calls the current state of physics into question

So you probably try to check if it can't work in the usual context

Cows

@DanielSank nice, thank you

Slereah

If you propose a revolutionary new thing and it turns out you just fucked up your calculations you'll never hear the end of it!

Cows

hehe

bolbteppa

19:29

Epicycles link to Fourier explained by the one (praise) motls.blogspot.com/2008/07/myths-about-epicycles.html

Slereah

Praise Motl

"Believing otherwise was equivalent to a heresy - a belief that God and Nature were sloppy prostitutes."

bolbteppa

19:44

rationalwiki.org/wiki/Adding_epicycles#What_actually_happened

More of that 'it could theoretically be used to match any observations. Adding epicycles is the fastest way to make sure that Occam's razor renders your theory implausible, hum hum' thinking, even though they would end up finding the right path with those epicycles

Semiclassical

20:21

"If God did not exist, it would be necessary to invent him."

Slereah

how does one invent a god

Semiclassical

(which is my cryptic way of saying that the myth of "just add more epicycles" has entered into the scientific parlance as a shorthand for theories/models which are overly complicated. the original example really didn't work that way, but it's such a convenient story that people keep using it)

Slereah

"What are the strings in string theory made of?"

will I get in trouble if I answer "yarn"

vzn

21:24

@Semiclassical lol "to the extent copernicus model was a shift..." it was only one of the largest "shfits" in the entire history of science...

Semiclassical

uh

in mindset, perhaps. in technique, not really at all.

vzn

not familiar with specifics but guess you are asserting copernicus still used epicycles. but the change in the model aka (correct!) "interpretation" of the epicycles led directly to discovery of elliptical orbits by kepler...

Semiclassical

I think you are vastly oversimplifying it.

It's hard to call any interpretation of Copernicus's (additional!) epicycles as "correct" except insofar as they pointed obscurely to the notion that the correct orbit was not quite circular.

vzn

@Semiclassical dude, something is being lost here. were talking about a geocentric vs heliocentric theory and you somehow dont think the latter was a fundamental paradigm shift?

Semiclassical

for Copernicus himself, not necessarily

The reason why Copernicus did his model the way he did was not because he believed that "the earth must revolve around the sun!"

vzn

21:32

@Semiclassical sorry not following

Semiclassical

"Copernicus added an extra epicycle to his planets, but that was only in an effort to eliminate Ptolemy's equant, which he considered a philosophical break away from Aristotle's perfection of the heavens. Mathematically, the second epicycle and the equant produce the same results, and many Copernican astronomers before Kepler continued using the equant, as the math was easier."

that's quoting from Wikipedia (risky, I know)

(also, note that Copernicus's model made the math harder. Not what you'd expect if you suppose that Copernicus's mindset made things simpler!)

vzn

> The Copernican model replaced Ptolemy's equant circles with more epicycles.[29] This is the main reason that Copernicus' system had even more epicycles than Ptolemy's.

@Semiclassical you think he had some other motivation? and what is that?

Semiclassical

First line of the quoted section reads pretty clearly

For Aristotle, the motion of the planets should be uniform and circular

vzn

> It opened with an originally anonymous preface by Andreas Osiander, a theologian friend of Copernicus, who urged that the theory, which was considered a tool that allows simpler and more accurate calculations, did not necessarily have implications outside the limited realm of astronomy.

Semiclassical

To the extent that Copernicus preferred more epicycles to the equant, I think a not small part of that is that you get a description entirely in terms of circular motions

the equant is simpler calculationally but doesn't respect that theoretical principle

For a longer critique, this is where I'd look: dash.harvard.edu/bitstream/handle/1/4258973/…

(full disclosure: I"m partial to Gingerich since his book on the reception of Copernicus's De revolutionibus orbium coelestium is where I first learned about the problems with the epicycles story)

Following that linked source, I guess I should distinguish between two possible 'crises.'

One is the supposed astronomical one, with the Ptolemaic system becoming overly complicated in order to fit the known data. That's pretty much just entirely false.

vzn

21:46

sigh looks like woit is going to censor my comment on new physics given that a later comment appears below mine, not yet appearing and saying still "your comment is awaiting moderation"... math.columbia.edu/~woit/wordpress/?p=10147 ... similar to my reddit comment already at -8 votes :P reddit.com/r/Physics/comments/87q1sy/…

Semiclassical

But one can read a cosmological crisis as being in play as Gingerich notes on page 7

ACuriousMind

Given that Woit explicitly says "In addition, remember that this is not a general physics discussion board, or a place for people to promote their favorite ideas about fundamental physics. ", you can hardly be surprised a comment on "new physics" is not going to appear.

vzn

@Semiclassical (massive) paradigm shifts do indeed look like "crises" within scientific circles.

@ACuriousMind lol saw that. woit seems to use it for that purpose along with lots of other commenters.

Semiclassical

Well, there's the thing. The Copernican shift is only a crisis in retrospect.

vzn

@Semiclassical it was a crisis at the time. is that what youre saying? but that is exactly the kuhnian view.

Semiclassical

21:50

I'm saying the exact opposite.

I'm saying that within the community of medieval astronomers there was precisely not such a view that the Ptolemaic model was in crisis.

vzn

@Semiclassical the crisis is larger than a single community. the "crisis" was in the scientific community seeking a larger truth. the two theories are obviously incompatible to say the least. they are completely different realities. but it took a long time for "everyone" to realize that. and maybe the obfuscated/ convoluted epicycle math "naturally" made it difficult.

Semiclassical

"After criticizing the alternative system of homocentric spheres, and indirectly, Ptolemy's
equant, Copernicus says:

'Nor have they been able thereby to discern or deduce the principal thing--namely the
design of the universe and the fixed symmetry of its parts. With them it is as though one
were to gather various hands, feet, head and other members, each part excellently drawn, but not related to a single body, and since they in no way match each other, the result would be monster rather than man.'

My point is that, were you a medieval astronomer in the time of Copernicus, you would hardly have thought there was a "crisis" going on. It simply didn't look like that.

vzn

> From publication until about 1700, few astronomers were convinced by the Copernican system, though the book was relatively widely circulated (around 500 copies of the first and second editions have survived,[34]

↑ wow ~1½ century to figure out the truth/ reality even by pro scientists/ experts. apparently some paradigm shifts can take a long time... o_O

Semiclassical

I’d say that goes to the fact that, while there is a unification present in the Copernican system, it is still a model that is built up and constructed in terms of Ptolemy’s model. As such, it can only accomplish that (while remaining consistent with the reliability of the Ptolemaic system) by making things more complicated not less

vzn

@Semiclassical right, copernicus only introduced the copernican revolution and it was built on heavily by kepler/ newton. it took a few centuries to fully play out. the interpretation and the math are worthwhile to study as two separate/ coupled "tracks" that go in and out of alignment so to speak. the early theory was rather convoluted as phrased in the language of epicycles. it took centuries to discover the mathematical simplicity of ulterior ellipses. aka a hidden variable theory :P

Semiclassical

22:02

In the terms that most medieval astronomers knew, the Ptolemaic system really was “simpler” than the Copernican one

So in that respect it’s not surprising that it took a while for people to appreciate the real significance of what Copernicus had done

vzn

@Semiclassical its helpful to study to understand a key example of how math can both obscure or illuminate. "simple" can be a very subtle/ tricky word to apply in practice.

Semiclassical

Agreed

Part of what I’m insisting, though, is that astronomy in that era was not acting like a community in crisis. As a method for getting predictions , the Ptolemaic model worked very well

vzn

@Semiclassical think you have excellent point that copernicus, for all his "revolutionary" ideas, was still using epicycles, and they were even a bit more complex than ptolemys, that is probably missed by many and agreed some conventional wisdom may be inaccurate on some of the historical details. anyway epicycles were thrown out centuries ago ("dustbin of history") and its not surprising that their exact history is collectively not so well remembered or even misremembered...

Semiclassical

Eh. I’d be more okay with that last point were it the case that epicycles were soundly forgotten

vzn

Dec 13 '16 at 17:54, by vzn

> The crisis consists precisely in the fact that the old is dying and the new cannot be born; in this interregnum a great variety of morbid symptoms appear. https://en.wikiquote.org/wiki/Antonio_Gramsci

Semiclassical

22:11

If the Ptolemaic way of thinking was dying, it had been dying for more than a thousand years

But anyways

vzn

@Semiclassical lol ideas/ memes can be quite tenacious. aka "gripping." its human nature. o_O

Semiclassical

It’s hard to argue with success unless you have some deeper principle in which to challenge it

And the Ptolemaic model was reliable

vzn

@Semiclassical yes, and can anyone even point to exact astronomical observations that discriminate the ptolemaic vs copernican models? honestly cant even think of anything myself. which shows how difficult popperian falsfiability ideal is in practice.

Semiclassical

It’s definitely not easy

vzn

@Semiclassical thinking about it, maybe/ possibly the way to think about it is that the empirical refutation of the ptolemaic system is newtons theory of gravitation, which makes testable predictions and predicts elliptical orbits etc.

Semiclassical

22:17

My overriding issue, though, is that the word “epicycles” has not faded away. As the comment of Jim Baggott shows, that myth has entered into the Science lexicon

I don’t mind it being forgotten but I do mind it being misused for rhetorical convenience, especially when it’s a writer I like

vzn

@Semiclassical think the comment was only ~¼ misleading :P

@Semiclassical its a worthwhile history to study of which even mainstream scientists may be weak on the exact details, thx for refresher course :)

Semiclassical

Maybe. In fairness I may be overly sensitive to it

vzn

"epicycles" are invoked to illustrate various rhetorical points, not all of them grounded by the history.

Semiclassical

Once you’ve been inoculated against that example, so to speak, it’s hard not to be annoyed

Right.

If you’re interested, I really do suggest that book by Gingerich. It’s a good read

vzn

@Semiclassical a friend once recommended Koestler & see him cited a bit on wikipedia.

Semiclassical

22:30

Heh

Yeah, Gingerich takes Koestler’s word on Copernicus to task

One historical question I don’t know: How long did it take for the Ptolemaic system to stop being used?

And, what superseded it? It wouldn’t surprise me if that had an interesting answer

vzn

@Semiclassical are you talking about the ~11p essay you just cited? full of interesting stuff, (skimming it) he is quite critical of Kuhn, but still think its great to see a hardcore scientist engage with Kuhn, dont see it all that often.

Semiclassical

No, I mean the book

A big motivation for the research behind it was Koestler’s remark in “The Sleepwalkers” that nobody read Copernicus’s book

vzn

@Semiclassical ok looks cool. its nice to engage with someone conversant with some of these ideas. now wondering if you minored in philosophy?

@Semiclassical that presumably offhand comment reminds me of A brief history of time :P

Semiclassical

Gingerich was curious about that, so he set out to do a census of all extent copies of the first printings of Copernicus’s De Revolutionibus

And that ended up being a bigger project than he expected

One which pretty well debunked it being a book that nobody read

@vzn nah, I’m a philosophical dilettante

vzn

> Arthur Koestler described De revolutionibus as "The Book That Nobody Read" saying the book "was and is an all-time worst seller", despite the fact that it was reprinted four times.[27]

Semiclassical

22:42

But I read that book in high school (I think? Maybe college), and it left an impact

vzn

possibly Koestlers point stands that there was possibly (relatively) very low publication/ readership/ recognition of the book despite its significance. esp popular readership.

Semiclassical

Possibly. It was definitely a technical text

Quoting from the NYT review of the book:

“(Here is the place for full disclosure: I have never read the Copernicus book cover to cover, only excerpts pertaining to, as the title page promised, the ''wonderful new and admirable hypothesis.'' At least 95 percent of the text, Gingerich tells us, is ''deadly technical,'' allowing me to rationalize that it was better to suffer guilt over not having read it all than to risk the embarrassment of incomprehension if I had.)“

vzn

@Semiclassical Gingerich? what impact?

Semiclassical

Impact is perhaps too strong a word. But it left an impression, as my interest in the topic probably shows

vzn

22:59

@Semiclassical "impact" is perhaps the perfect word :)

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