History of Heliocentrism

[Sir Og]

This is almost on topic.

Meeting a friend in the corridor, Ludwig Wittgenstein (1889-1951) said: "Tell me, why do people always say that it was natural for men to assume that the sun went around the earth rather than the earth was rotating?"

His friend said: "Well, obviously, because it just looks as if the sun is going around the earth."

To which the philosopher replied: "Well, what would it look like if it had looked as if the earth were rotating?"

[BeBMan]

Well given the speed cosmic objects are moving there should really be more motion blur in the sky, and since there isn't it is proof enough that we're all living inside the hollow earth

[Aeson]

If Earth is rotating, why aren't I dizzy?

[Lorizael]

This is almost on topic.

Meeting a friend in the corridor, Ludwig Wittgenstein (1889-1951) said: "Tell me, why do people always say that it was natural for men to assume that the sun went around the earth rather than the earth was rotating?"

His friend said: "Well, obviously, because it just looks as if the sun is going around the earth."

To which the philosopher replied: "Well, what would it look like if it had looked as if the earth were rotating?"

There are detectable differences due to diurnal rotation that had not been observed in the 17th century. Although geocentrists at the time didn't use this language (and didn't have the physics exactly right), they argued that a rotating Earth was a rotating reference frame, which should produce fictitious forces such as the Coriolis effect for projectiles and falling objects. No one had observed those effects, so it seemed reasonable to conclude they weren't there.

The other missing observational effect of a moving (revolving) Earth was annual parallax. The stars should change relative positions as the Earth moves about its orbit, but no annual parallax was detected until the 19th century. If Earth was moving but no parallax was present, the only conclusion was that the stars must be unthinkably distant. That might be okay, but given their apparent size, such a distance would imply that stars were physically gigantic--like, at a minimum the size of Earth's entire orbit. There was no good reason to believe the stars were that far away and that big.

Stars are not that big, of course (usually). Their apparent size is an illusion resulting from diffraction effects. But optics at the time was not sufficiently advanced to account for that. In fact, while we know all this today, even the best modern telescopes cannot resolve the physical surface of a star; they are only seeing the illusory Airy disk. (Optical interferometry is starting to change this.)

[Sir Og]

There are detectable differences due to diurnal rotation that had not been observed in the 17th century. Although geocentrists at the time didn't use this language (and didn't have the physics exactly right), they argued that a rotating Earth was a rotating reference frame, which should produce fictitious forces such as the Coriolis effect for projectiles and falling objects. No one had observed those effects, so it seemed reasonable to conclude they weren't there.

The other missing observational effect of a moving (revolving) Earth was annual parallax. The stars should change relative positions as the Earth moves about its orbit, but no annual parallax was detected until the 19th century. If Earth was moving but no parallax was present, the only conclusion was that the stars must be unthinkably distant. That might be okay, but given their apparent size, such a distance would imply that stars were physically gigantic--like, at a minimum the size of Earth's entire orbit. There was no good reason to believe the stars were that far away and that big.

Stars are not that big, of course (usually). Their apparent size is an illusion resulting from diffraction effects. But optics at the time was not sufficiently advanced to account for that. In fact, while we know all this today, even the best modern telescopes cannot resolve the physical surface of a star; they are only seeing the illusory Airy disk. (Optical interferometry is starting to change this.)

That's interesting, I didn't know all those details.

For me the story is that people made some assumptions and they turned out to be wrong.
I think the fundamental reason for assuming what people were assuming was the intuition that if you are moving you should feel it and it didn't seem like that.

[Berzerker]

http://pareidoliaplanets.blogspot.com/2014/11/sigillo-sumero-va243.html

there ya go, 4500 year old heliocentrism

and before dismissing it, the depiction matches up with the Babylonian Enuma Elish or epic of creation re-enacted each new year over the course of 12 days

[Lorizael]

That's interesting, I didn't know all those details.

For me the story is that people made some assumptions and they turned out to be wrong.
I think the fundamental reason for assuming what people were assuming was the intuition that if you are moving you should feel it and it didn't seem like that.

That is one of the arguments put forward by people who opposed heliocentrism. Galileo laid out (what now gets called) Galilean relativity in order to dismantle that objection. But I honestly think that it was an empirically reasonable assumption to believe the Earth was motionless and the heavens spun about it. We suffer from some presentism now because we've all seen pictures of both the Earth and the planets, but for the vast majority of human history, the Earth was a gigantic slab of rock always beneath your feet and the planets were stars that moved in weird patterns and didn't twinkle. There was no good reason to equate the two, and consequently no good reason to believe the Earth could be just another planet orbiting the Sun.

...

Despite evidence to the contrary, I didn't create this thread just to regurgitate some history of astronomy at people. I've been reading recently about the geocentrism/heliocentrism transition, and historians of science are very eager to point out that the common view of this period (Galileo the uber-scientist against the evil, unscientific Church) is not historically accurate. Now, I suspect it's true that most people hold to the view that the Church is unambiguously the bad guy in this story, but I wonder whether people actually have solid opinions on the scientific debate that was occurring at the time.

[Buster Crabbe's Uncle]

I have a solid opinion that Tycho Brahe should have gotten up to pee sooner.

[Lorizael]

Tycho knew how to party.

[Sir Og]

That is one of the arguments put forward by people who opposed heliocentrism. Galileo laid out (what now gets called) Galilean relativity in order to dismantle that objection. But I honestly think that it was an empirically reasonable assumption to believe the Earth was motionless and the heavens spun about it. We suffer from some presentism now because we've all seen pictures of both the Earth and the planets, but for the vast majority of human history, the Earth was a gigantic slab of rock always beneath your feet and the planets were stars that moved in weird patterns and didn't twinkle. There was no good reason to equate the two, and consequently no good reason to believe the Earth could be just another planet orbiting the Sun.

...

Despite evidence to the contrary, I didn't create this thread just to regurgitate some history of astronomy at people. I've been reading recently about the geocentrism/heliocentrism transition, and historians of science are very eager to point out that the common view of this period (Galileo the uber-scientist against the evil, unscientific Church) is not historically accurate. Now, I suspect it's true that most people hold to the view that the Church is unambiguously the bad guy in this story, but I wonder whether people actually have solid opinions on the scientific debate that was occurring at the time.

All scientific debates are a bunch of old guys with high social status shooting down new ideas from new guys who sometimes are correct. It takes some really solid evidence + time to move to a better (more correct) consensus.

This reminds me of the story about scurvy and vitamin C. I don't know how widely know this is but in the beginning of 20th century there was a comeback of scurvy and everybody had forgotten how to cure it. It's a fascinating story regarding scientific progress/regress.

Here is the story:

http://idlewords.com/2010/03/scott_and_scurvy.htm

Short summary:

Yes, this really happened: scurvy was "cured" as early as 1497, when Vasco de Gama's crew discovered the power of citrus...but this cure was repeatedly lost, forgotten, rediscovered, misconstrued, confused, and just generally messed around with for hundreds of years, despite being a leading killer of seafarers and other explorers. By the 1870s the "citrus cure" was discredited, and for nearly sixty years, scurvy -- despite being cured, with scientific research to back it up -- continued killing people, including men on Scott's 1911 expedition to the South Pole. This went on until vitamin C was finally isolated in 1932 during research on guinea pigs. Self-described painter/computer guy Maciej Ceglowski gives us the absurdly fascinating story of scurvy -- a bizarre tale of science gone wrong, and a really good explanation of why you should eat a bit of citrus once in a while. (I would argue from this piece alone that Ceglowski needs to add "science journalist" to his title.)

[Lorizael]

Very interesting story. I especially like this concluding bit:

First, the fact that from the fifteenth century on, it was the rare doctor who acknowledged ignorance about the cause and treatment of the disease. The sickness could be fitted to so many theories of disease—imbalance in vital humors, bad air, acidification of the blood, bacterial infection—that despite the existence of an unambigous cure, there was always a raft of alternative, ineffective treatments. At no point did physicians express doubt about their theories, however ineffective.

Second, how difficult it was to correctly interpret the evidence without the concept of ‘vitamin’. Now that we understand scurvy as a deficiency disease, we can explain away the anomalous results that seem to contradict that theory (the failure of lime juice on polar expeditions, for example). But the evidence on its own did not point clearly at any solution. It was not clear which results were the anomalous ones that needed explaining away. The ptomaine theory made correct predictions (fresh meat will prevent scurvy) even though it was completely wrong.

I associate with scientific skepticism, so I frequently argue that we should be more confident in the consensus of scientific experts within their area of expertise than any random opinions that might come from without. But "more confident" does not indicate specifically how confident we should be. I think we have reason to be more confident generally in science now than in the past, but again that's not specific and still leaves open the possibility (which happens from time to time, because science is all about updating our models) that the consensus will turn out to be wrong.

So the tricky part is figuring out if there are times when we have good reason to doubt a scientific consensus at any point before the current edifice of theory comes crashing down. That is, are there features of a research program we can look at and say, "This part is good science; that part is bad science"? This is the demarcation problem, but philosophers of science today are skeptical about whether a good solution to it exists. (Even the popular-with-scientists Popperian falsification criterion has plenty of problems.)

[Buster Crabbe's Uncle]

You know - my cosmology crankery is based in, not that I don't think the experts don't know what they're doing, but in questioning the data and base assumptions - I'm not convinced that our observations are complete enough, and I'll see your dark matter fudge factor to explain galaxies with science's great cosmological blunders like the spheres, aether, plogiston, and so on - the ancients weren't stupid -except for the ones who were- but their observations were incomplete and nobody had thought of a better model yet. I strongly suspect that's where we are, now, the cosmolgy group mind gone down a --- wrong turn...

[Lorizael]

We've talked about this before, but I don't think dark matter is the new aether (or whatever). There are two main reasons why. The first is, as I've mentioned previously, a number of past scientific missteps were based on assumptions about how the world must behave. With the aether, for example, it was believed that because light is a wave, and waves were understood to be a disturbance in some type of medium, that light must be propagating through a medium--the aether. The critical incorrect assumption about the world was: waves must propagate through a medium. We now understand wave phenomena to be a more general mathematical/physical concept that happens to get expressed in everyday experience as a propagating disturbance.

I don't think dark matter falls prey to a similarly stealthy incorrect demand about the world. It's an explanation for our observations, but the explanation does not currently lend itself to a very direct form of empirical confirmation. Here's the thing, though: nature has no obligation to provide us with the most direct evidence of its parts. I would argue, in fact, that believing everything we see in nature must be readily observable by one of our evolved senses is clearly a demand about the universe which has no reason a priori to be true. To beings that evolved next to the warping spacetime of a black hole, for example, dark matter's gravitational effects might be instantly empirically obvious.

Secondly, dark matter is not a fudge factor. We don't just insert X kg of dark matter into the universe to make the equations work. Multiple, independent lines of evidence all converge on relatively tight constraints for properties such as, say, how much dark matter is out there.

[Ben Kenobi]

Well given the speed cosmic objects are moving there should really be more motion blur in the sky, and since there isn't it is proof enough that we're all living inside the hollow earth

Thank Bessel for that

[Ben Kenobi]

I've always been a fan of the theory that gravity has a mildly repulsive cubic term.

As for empiricism - you do realize that the reason we can see things in the universe is because we are a part of the universe too? It's not a coincidence that our light sensitivity is highest to certain parts of the spectrum, that it works on a logarithmic scale, that we're carbon based life, etc.