I'm not convinced that the author is as knowldegeable as he thinks he is.
quote:
"We might expect to see some stars growing brighter throughout the spring on account of Earth approaching them, and then growing dimmer throughout the fall. There is a name for this sort of effect: parallax. But no one could see any parallax."
Dimmer and brighter through relative motion is parallax now?
I had something of a double-take on this part too. A difference in apparent magnitude throughout the year isn't the same as stellar parallax by any means, and is something of a misnomer.
> The photometric parallax method is a method of data analysis used in astronomy that uses the colours and apparent brightnesses of stars to infer their distances.
That page seems to be saying they estimate the star’s brightness by its color, then distance by its apparent brightness. If so, that’s an unfortunate name because it’s been seriously proposed to measure distance by how much the apparent brightness changes at half-year intervals. (But the particular seasons would of course be different for different stars.)
But "misnomer" also means an inappropriate designation ("lousy choice of rubric") that is nonetheless the official designation. It's correct to refer to Greenland by that name even though it's mostly ice, and therefore a misnomer.
https://www.merriam-webster.com/dictionary/misnomer
So the article's author isn't exhibiting ignorance, he just has to use the only word we have, parallax.
My favorite misnomer is "bacterial competence." When damaged and so incompetent they need replacement DNA, bacteria open up to allow spare parts (from other similar bacteria that have been blown up) in. The name for this kind of incompetence in bacteria? "Competence!"
My misnomer pet peeve is "passive restraints" in cars. These are restraints like airbags and automatically-applied seat belts that actively restrain the occupant. They're called "passive restraints" because, by being active, they allow the occupant to be passive (not having to bother latching the seat belt manually) and still receive the benefit of the restraint.
Perhaps this poor choice of words meant to say that the stars become brighter as we move towards them simply because the earth is closer to them. On one side of our orbit we should be closer to some stars and further away from others, resulting in a seasonal dimming. That would be logical to anyone who doesn't grasp the distances involved.
The dimmer and brighter is because when you are closer to a light source it is brighter, and when you are farther from it it is dimmer. So when we are closer to a star, we expect to see it brighter than when we are farther.
Yes, that’s a real effect, but that’s not the meaning of the word parallax.
“Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines”
I am fully aware of the meaning of the word "parallax". See my response to your other comment. I am just answering why a variation in brightness would have been expected.
Objects definitely do get brighter* when coming towards you and dimmer when going away from you, but this is special relativity, not parallax. It certainly wasn't known at that time.
* The light becomes more energetic, anyway, thanks to blue shift. Whether you count this as brighter depends on how you define brightness.
Thanks for posting. Great article. A word of caution about Kepler's discovery of elliptical orbits. We usually encounter this topic in physics textbooks who illustrate the ellipticity of planetary orbits with highly eccentric ellipses of probably 0.7 or more ecentricity. But, as an example, the eccentricity of Venus' orbit is 0.0068! So if you draw such an ellipse on letter size (or A4) paper you cannot tell it apart from a circle.
I agree. It's not their fault. What interests me is this: If the eccentricity of planetary orbits is so small, I wonder if we can still uphold the circularity of orbits, but place the sun slightly off center? Will this geometry save the observations?
In particular (you can take this as a TL;DR summary), it is about the myth that some people were stupid (for example, to oppose ideas of Kepler or Galileo), while others were smart. They were all pretty smart, and the opposition to new ideas actually had math and data (that were available at the time!) on its side. Kepler's model, for example, required a believe in gigantic stars (all starts are the size of Betelgeuse or even larger), based on data available at the time, which today we know was wrong. Somewhere else I read about Galileo, as far as I remember apparently his telescope was pretty bad and it wasn't that other astronomers refused to look through it, as our modern myth about their "stupidity" goes, but that what could be seen was not conclusive. I may be wrong about the last one, this is from what I read long ago elsewhere, the Kepler theory is a main theme in the linked article though.
> How Marius Was Right and Galileo Was Wrong Even Though Galileo Was Right and Marius Was Wrong -- or, how telescopic
observations in the early 17th century supported the Tychonic geocentric theory and how Simon Marius realized this.
Sometimes scientists who followed their instincts were right, and those who followed the available facts/data were not. Sometimes. Or in other words: Things are not that simple.
It should be noted that Brahe's model was not the classical Ptolemaic geocentric / epicyclic model: "It is conceptually a geocentric model: the Earth is at the center of the universe, the Sun and Moon and the stars revolve around the Earth, and the other five planets revolve around the Sun." [1]
The Popperian model of science suggests that it steps from one empirically-sound but falsifiable position to another, but that is the view with hindsight - what happens at the leading edge is much more fluid, and having the right sort of instincts about where the evidence is leading is not just a matter of luck. Heliocentricity was generally accepted well before stellar parallax was observed.
It appears to me that MOND (Modified Newtonian Dynamics) seems to be going the way of Brahe's model - it fitted the initial data, but does not seem to work consistently for the general case.
The author of that article (Graney) on Galileo's observations teaches at a nearby university, and I was able to attend a lecture he gave about the effect.
The tl;dr is that when you look through a telescope today stars are pinpoints. You can magnify them as much as you want, and they still appear pinpoints. Brighter stars might appear larger than smaller ones, but their size doesn't change with magnification. Galileo's telescope had such a small aperture that diffraction distorted the image, and the size of the disk of a star did change with magnification. Since they didn't understand diffraction at the time, they thought they were seeing the star's disk. Since there was no measurable parallax on stars at the time, they knew they had to be very far away, and thus unbelievable enormous in order to have a disk visible in a telescope.
"The Great Ptolemaic Smackdown" [0] also provides information to this effect. Yes, as the link you provide mentions, there's an optical phenomenon known as the Airy disk that suggests an incorrect apparent size of stars when looking through such old telescopes. It wasn't until the 1800s that this phenomenon was understood.
"the above-mentioned Galileo, because of the things deduced in the trial and confessed by you as above, have rendered yourself according to this Holy Office vehemently suspected of heresy, namely of having held and believed a doctrine which is false and contrary to the divine and Holy Scripture: that the sun is the center of the world and does not move from east to west, and the earth moves and is not the center of the world, and that one may hold and defend as probable an opinion after it has been declared and defined contrary to Holy Scripture."
"after having been judicially instructed with injunction by the Holy Office to abandon completely the false opinion that the sun is the center of the world and does not move and the earth is not the center of the world and moves, and not to hold defend, or teach this false doctrine in any way whatever, orally or in writing; and after having been notified that this doctrine is contrary to Holy Scripture; I wrote and published a book in which I treat of this already condemned doctrine and adduce very effective reasons in its favor, without refuting them in any way"
The premise of the whole series by that author is also wrong, approximately, that because the parallax wasn't observed until around 1750 Galileo couldn't prove in 1633 that the Earth is not standing still, therefore the Church was right and it wasn't a matter of faith but a personal thing. It's obviously a completely invalid argument.
It's an invalid argument only after you twisted it very severely to fit your preconceptions. I see a lot of carefully selected random out of context quotes.
"carefully selected random out of context quotes" is exactly what the "smackdown" makes: its avoid mentioning the truth:
- the clearly written sentence
- clearly written statement by Galileo
- the fact that the rotation of the Earth around the Sun was obvious to anybody who actually "did the math" and compared with the observations, even at that time
- the fact of how long both Galileo's and Copernicus' books remained banned by the Church afterwards
and instead claims that "missing parallax observation" made right for the Church to claim "heresy." No it doesn't and that particular detail was never relevant. Even now we don't know what's beyond the limit of our observations, but because of that we don't punish the scientists who make the best models for what we actually observe.
So yes, the Church was very wrong, and there are very clear written documents. Including that both Galileo's and Copernicus books remained on the Church's list of banned books for the next centuries!
The guy writing "smackdown" seems to be in a search for anything to prove actions of the Church "acceptable" by intentionally avoiding the major facts: yes the Church considered exactly even teaching or writing about the heliocentric world a real heresy. And it acted according to that not only in one point of time but through the centuries, obviously not because "Galileo had a bad personal problem with the Pope of that moment" or anything else that the "smackdown" guy wants to pass as a "good reason". The "smackdown" guy should be smackdowned and recognized as effectively a liar.
I know a lot of people "want to believe him" and that link to his page is resent around, but it doesn't make it true.
Not so much; people who -could see- the phases of Venus were in possession of -conclusive- data that it was not moving in a circle between the Earth and Sun.
"Although the extreme crescent phase of Venus has been observed with the naked eyes, there are no indisputable historical pre-telescopic records of it being observed."
https://en.wikipedia.org/wiki/Phases_of_Venus
There may be no records, but that might not have stopped ANYone with keen eyesight from knowing (including the Greeks back to Aristarchus, or even the Babylonians). For 2000 years, the 'authorities' (e.g. Aristotle) were wrong.
No, I don't think that would have been considered solid data in any time period. It's almost the definition of "things only very few people claim to see".
There are no records of it from the ancient world, and "Venus with horns" could mean anything.
> For 2000 years, the 'authorities' (e.g. Aristotle) were wrong.
Careful to not let desires and personal aspirations cloud your judgment there.
This article doesn't understand the word "star". We use it to mean a particular class of object, things like our sun. For Copernicus a "star" was anything other than the known planets. The term "fixed stars" is needed to differentiate between what we call stars and all the other moving things that today we call comets, shooting stars. The "fixes stars" included galaxies, nebula, and all the other non-star things that seem fixed to the celestial sphere. May of these were indeed as large as a "universe". Galaxies are big enough to be so described.
Star also often mean a sign, symbol or temporary object. The "star" in the Christmas story was likely an alignment of planets. Such stars could appear and disappear on a nightly basis. Before criticizing the ideas in old texts we need to make sure we understand the actual words.
>Copernicans like Thomas Digges, Christoph Rothmann, and Philips Lansbergen, spoke of the giant stars in terms of God’s power, or God’s palace, or the palace of the Angels, or even God’s own warriors. [...] The anti-Copernicans were unpersuaded.
If you aren't the guy to be in some way off put by the way science and religion were rubbing together in this instance or by the sort of historical baggage implied in it, then this is perhaps one of the funniest things -- as in genuinely funny -- about Early Modern science and philosophy. That's what I think, at least. Everyone kept invoking God as if that were an argument, but whenever tables turned and people went through the same motions on the listening side they just went "... yeah, nah, I don't think so."
That's interesting about the "giant star" hypothesis. I never knew that, and it makes sense based on what Kepler knew at the time.
Today, we know that the apparent size of stars is an illusion due to diffraction. In principle, even if stars actually were infinitesimal points of light, they would still appear as disks in optical instruments. Smaller apertures (like our eyes) make the disks larger. Only in recent decades with special techniques can we resolve the actual apparent size of a star.
All you need to do to kill someone's belief in the Big Bang theory is tell the entirety of it. You know, a little more than just the very beginning.
Once you get to point out that a part of the theory says that a solar system sized ball of "fire" suddenly expanded to the size of our galaxy in <2 seconds for no reason whatsoever (ie. inflation, or should we say "the second inflation", and yes seriously, that was a pure coincidence according to the accepted-but-don't-ask theory) people start going "what ?". And then go on to explain why it's utterly impossible for space to be 3 dimensional, or for gravity to exist (the standard model argument against gravity) or for gravity to not exist (relativity, as well as obvious experience).
And this is probably the right reaction. There's more, like why weren't the electrical, gravitational, magnetic, ... forces between matter and antimatter in that small ball enough to do lots of things. Create a black hole, for instance. Annihilate for instance.
I mean there's answers for these questions, but I assure you, whilst they work in the equations (sort-of), they will not reduce the WTF-rate.
Just because this is the best theory we have does not mean it's a particularly sensible one. I mean it is, it's just a matter of perspective. When it comes to "intuitive", I contend the actual big bang theory scores pretty damn bad.
The Magic Furnace is a great book about the history of how we came to understand atoms and where they come from. It shows a lot of the missteps and twisty turns along the way.
I also love learning about how scientific understanding actually developed over time. It's a messy, fascinating process.
Sure, look for The Great Ptolemaic Smackdown[1]. It's about the same period but in much finer detail, more accurate, and much more entertaining to read.
I wanted to read the article, but unfortunately it requires me to activate cookies or to subscribe.
I was about to create an exception for nautil.us but I had a Wait-Why-Should-I moment. Now I find that request unacceptable, really. They're blocking my access to some article because
"Nautilus uses cookies to manage your digital subscription and show you your reading progress. It's just not the same without them."
Yes, it is. It is exactly the same. If nautil.us can't go without a cookie, I can go without reading their articles.
Without cookies they can't log you in so if you have a paid subscription it'd not work.
From what I see they also store on cookies where you've stopped so if you return to the article it's on the same point.
In that sense it's not the same experience without them.
And it's not unimaginable that they track how many articles you've read a month so they can show you a modal to interest you in a subscription.
I can see how you'd not want to be tracked as a visiting user, but even then it's not really sensible to complain when the other option (paying for the content) requires you to activate cookies anyway.
Honestly, I don't think it's reasonable to expect (or find it odd) that websites need cookies to function inside a browser in this day and age.
I think that they have the right to ask for whatever they want to ask, just as much as I have the right not to concede them what they're asking.
I know I need to activate cookies in order to login. I do have a lot of cookie exceptions. But in my opinion, this is not one of thoses cases.
One does not require cookies to read HN, for instance. Or many other websites.
If they use cookies as a base for their business model - which is perfectly acceptable - at least they could have the decency of saying so clearly. I dislike being treated as too ignorant to understand, and the "user experience" card is getting old.
I just accessed the site with javascript disabled (my default setting) and read the article just fine (no cookies, no messages to the effect you reported).
>Planets do not even orbit around sun, but center of gravity which is outside of sun.
That's...semantics also. The barycenter (center of mass, not gravity) of the solar system can very much be within Sol's limb. For all intents and purposes the planets do orbit the highest center of mass which is within or at least very close to the surface of Sol.
>That dynamism stands in contrast to the usual tales we are told about the birth of science, stories portraying the debates around the Copernican theory as occasions when science was suppressed by powerful, entrenched establishments. Stories of scientific suppression, rather than scientific dynamism, have not served science well.
Well, this doesn't make sense. Galileo was executed by the Inquisition, an institution inside the Catholic Church. The church was not interested in debating rival scientific theories. They only debated heliocentric theory and their own earth-centric dogma. Once they identified the heliocentric model to be against their dogma they supressed and punished anyone who advocated heliocentric notions. But this does not mean the church was ignorant of astronomy. The church was the main supporter of astronomy because of their interest in maintaining an accurate calendar. Christoph Scheiner mentioned in the article was a Jesuite astronomer respected by Galieleo and the two corresponded.
The title of the article must have been decided by an editor who did not read the article. He wanted to write something like “The popular stories we are told about the beginning of scientific thinking have been wrong.” The word “creation” is totally wrong. Astronomy was not created in the 17th century.
Was only arrested at home, for 10 years (but wrongly convicted)
> Once they identified the heliocentric model to be against their dogma they supressed and punished anyone who advocated heliocentric notions
I recommend reading [0], particularly:
> as in astrology the theory of eccentrics and epicycles is considered as established, because thereby the sensible appearances of the heavenly movements can be explained; not, however, as if this proof were sufficient, forasmuch as some other theory might explain them.
So, the Ptolemaic model was used because it fit the observations well enough.
On the other hand, the Copernicus work was (indirectly) used in the construction of the Gregorian calendar.
Furthermore, when Copernicus introduced is theory in 1543, the book was dedicated to the Pope.
The Galileo affair was made by enemies of Galileo who used the Inquisition to prosecute him. That was wrong, but it was certainly not the whole Catholic Church.
> Was only arrested at home, for 10 years (but wrongly convicted)
My mistake obviously. I was trying to say “Galileo was tried by the Inquisition. The point was that the Church had jurisdiction over academia and had the power to enforce its dogmas by force if necessary.
This only shows that just as there are religious myths about the history of science, there are also atheist myths about the history of science, and both sides have their "true believers" who will not be swayed by the historical record. The idea that the Catholic Church was on some monolithic crusade pitting scientific inquiry against scripture is a-historical. It wasn't true in the case of Galileo. (For the record, it wasn't true in the case of Columbus either.)
The biggest problems with the whole "Church vs. Galileo" had to do with politics, and the fact that Galileo was an arrogant jerk (despite being essentially right).
The Church was in the wrong, but not the way most people think, and Galileo did everything he could to make the situation worse. It's kind of like the sack of Constantinople... it was entirely wrong and is in no way justified, but the Byzantines went out of their way to make the situation worse.
The church was plenty interested in debating scientific theories. The church played a massive part in advancing science ever since the middle ages. They did expect scientific theories to fit both the scientific as well as the religious knowledge available, something that seems absurd now, but was perfectly workable based on the number of scientific discoveries made the past 1500 years.
I agree. This is why I wrote: “The church was the main supporter of astronomy because of their interest in maintaining an accurate calendar. Christoph Scheiner mentioned in the article was a Jesuite astronomer respected by Galieleo and the two corresponded.”
But here the subject is astronomy. I am not sure what other science the Church supported. But the fact that the Church was uncompromising about defending its cosmogonic dogmas is also proved by the burning of Giardano Bruno. They did not try to argue with Bruno and they did not try to reach a compromise. They just burned him.
I didn't read the phrase "creation story" as literally referring the start of astronomy. It's a punchy allusion that fits well with the themes and thesis of the article.
What does that have to do with anything discussed here, or said in the article you responded to? "Creation" is a word used for more than that one thing that seems to occupy your mind as its only use. Please consult a dictionary, the religious meaning is only one of many. When I create software I'm not doing anything religious as far as I can tell. Never even mind that the submission title explicitly states what "creation" is meant: "of astronomy" (that's a scientific field). One might argue whether Kepler & Co. mark the time and place where "astronomy" was created or whether the article's subject actually is the creation of astronomy or just a famous episode from its much longer history, still has nothing to do with your purely religious interpretation of a common word. If you actually read the article you will find that this article is about - astronomy. As promised in the title.
quote: "We might expect to see some stars growing brighter throughout the spring on account of Earth approaching them, and then growing dimmer throughout the fall. There is a name for this sort of effect: parallax. But no one could see any parallax."
Dimmer and brighter through relative motion is parallax now?