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ToSeek
2008-May-22, 07:49 PM
A Test of the Copernican Principle (http://www.physorg.com/news130673436.html)


The Copernican principle states that the Earth is not the center of the universe, and that, as observers, we don’t occupy a special place. First stated by Copernicus in the 16th century, today the idea is wholly accepted by scientists, and is an assumed concept in many astronomical theories.

However, as physicists Robert Caldwell of Dartmouth College in Hanover, New Hampshire, and Albert Stebbins of Fermilab in Batavia, Illinois, point out, the Copernican principle has never been confirmed as a whole. In a recent paper published in Physical Review Letters called “A Test of the Copernican Principle,” the two researchers set out to prove the 500-year-old principle using observations of the cosmic microwave background (CMB).

Jerry
2008-May-23, 02:55 AM
Interesting test - they are assuming that the Cosmic Microwave Background was originally uniform and Gaussian, therefore, any distortion may indicate a lopsided universe...but assuming the CMB was originally uniform is an assumption based upon...the Copernicus principle.

The Copernicus Principle can never be proven, or really disproven, since we only have one observational platform. We assume the principle is true because without it, we cannot meaningfully extrapolate from a single point in space and time.

George
2008-May-26, 02:23 PM
If they were to show Copernicus wrong, they'll have a hard time convincing anyone of Geocentricity. [Well, ok, not everyone. :)] It is unthinkable that the universe could be revolving around Earth given that this rate varies all the time and in close relation to events on Earth, e.g. air masses and tsunamis.

Their ATM finding would have a profound impact on gravity, too, I would think. What causal action would explain the Sun -- a million times larger than Earth -- [to] orbit the Earth? At the same time, the planets must orbit the Sun, since all the phases exist for Mercury and Venus.

ravens_cry
2008-May-26, 02:38 PM
Well, to be fair I don't think the they mean Sun orbiting Earth geocentricity, the article seems to refer to geocentricism on a larger scale then that. If classical geocentricism was true, wouldn't navigation for space probes have shown this by now?

George
2008-May-26, 05:54 PM
If classical geocentricism was true, wouldn't navigation for space probes have shown this by now? Good question. Based on my understanding of what the understanding likely is of others that express understanding of GR :), then this may not be the case, after all. The Ptolemy model fails, but the Tychonian model may not. [Hopefully a GRist will help us. ]

agingjb
2008-May-26, 05:59 PM
I suppose (no I don't really, but let's just speculate) that it would at some point have been plausible to say that the Earth was at the centre of things, but that it rotated daily.

George
2008-May-26, 07:31 PM
I wonder if anyone ever suggested that? The arguments against the Earth's motion around the Sun were similar to the arguments against Earth's rotation. It would have been a compromise, I suspect, and ad hoc in appearance. Of course, the Tychonic model could be argued as an ad hoc approach, too. It is interesting that it was quickly adopted by the Jesuit scholars once the phases of Venus were known, which falsified Ptolemy's model.

RationalMuscle
2008-May-28, 02:39 AM
http://jda.jaxa.jp/jda/v4_e.php?v_id=c11fcbc32fa7a2acfff7418328d4de8a&mode=search&genre=4&category=4064&mission=4067

The gig is up for the "earth doesn't move" crowd.

George
2008-May-28, 03:13 AM
Yes, but now the Moon is flat and only with one axis. ;)

Jerry
2008-May-29, 04:02 AM
If they were to show Copernicus wrong, they'll have a hard time convincing anyone of Geocentricity. [Well, ok, not everyone. :)] It is unthinkable that the universe could be revolving around Earth given that this rate varies all the time and in close relation to events on Earth, e.g. air masses and tsunamis.

Their ATM finding would have a profound impact on gravity, too, I would think. What causal action would explain the Sun -- a million times larger than Earth -- [to] orbit the Earth? At the same time, the planets must orbit the Sun, since all the phases exist for Mercury and Venus.
The Copernicus Principle is broader than geocentricity - it also implies the Sun, the galaxy and our local cluster are not unique, nor anything we observe in and from our tiny little corner. We can only see one aspect of the elephant, but if we see a trunk, there are many trunks.

Sam5
2008-May-29, 04:30 AM
The Copernicus Principle can never be proven, or really disproven, since we only have one observational platform. We assume the principle is true because without it, we cannot meaningfully extrapolate from a single point in space and time.


Back in the old days, the astronomers thought that the Milky Way was the entire universe, and so both Copernicus and Galileo thought that the sun was in the center of the universe, since the Milky Way seemed, in the old days, to surround the solar system.

It has never been proven or shown where the earth is inside the entire universe, since when we look out with our telescopes in all directions we see approximately an equal number of most-distant-galaxies in all directions, and this has always been true every time we manage to photograph more and more distant galaxies. The latest most-distant-galaxy photos taken by Hubble a couple of years ago show us to be in the center of our sphere of visibility, but that doesn’t mean we are in the center of the overall universe, since we’ve not found any outer boundaries of the universe yet. So, we’re not in the center of our solar system, we aren’t in the center of our galaxy, but we don’t know where we are within our universe, and we don’t know the extent of our universe.

Sam5
2008-May-29, 05:09 AM
The Copernicus Principle is broader than geocentricity - it also implies the Sun, the galaxy and our local cluster are not unique, nor anything we observe in and from our tiny little corner. We can only see one aspect of the elephant, but if we see a trunk, there are many trunks.

We don't yet know where our tiny little corner of the universe is. We didn't learn until early in the 20th Century where our tiny little corner of our own galaxy is.

I’ve been watching for Hubble photos for years for some evidence that might show some evidence of the overall size and shape of our universe, and where we are located within it, just as earlier studies revealed where we are within our solar system and within our own galaxy.

The circle in my first drawing below represents our present sphere of visibility. Imagine this being a 3-D image and the dots are galaxies. The circle represents our current maximum sphere of visibility which is limited by the power of our telescopes. We are in the center of that sphere (the center of the circle in the drawing). Disregard the square edge limits of the drawing, since I couldn’t make an infinitely large drawing. We don’t know what is beyond our current sphere of visibility.

Our current sphere of visibility within the universe:
http://i32.tinypic.com/20z4lnc.jpg

If our universe is spherical, and if some day Hubble or some other telescope manages to look outside our universe, to beyond the outer “edge” (if there is any), then this next drawing would represent what we should see. Note that our sphere of visibility should show no more galaxies beyond a certain limit in one direction of the sky, while we would still see distant galaxies in other directions of observation.

Edge of universe
http://i29.tinypic.com/2inviu.jpg

Of course, if the universe is infinite in size, we’ll never be able to see any outer edge or outer limit to it.

Hubble views, north and south, we see about the same number of galaxies in each direction, and no evidence of any outer limits of the universe:
http://www.cosmiclight.com/imagegalleries/deepfield.htm

This is one of the most recent deep field Hubble photos, compiled in 2004, in the direction of the constellation Fornax, near Orion. We see about the same number of most distant galaxies:
http://hubblesite.org/newscenter/archive/releases/2004/07/image/a/format/web_print/

http://hubblesite.org/newscenter/archive/releases/2004/07/text/

So, as of now, regarding our position in the universe, we are much like astronomers in the mid-19th Century who still could not determine where we were located within our own galaxy. Our position near an outer edge of our galaxy was not figured out until early in the 20th Century.

George
2008-May-29, 03:21 PM
The Copernicus Principle is broader than geocentricity - it also implies the Sun, the galaxy and our local cluster are not unique, nor anything we observe in and from our tiny little corner. We can only see one aspect of the elephant, but if we see a trunk, there are many trunks. Good point. I went straight after the thread title instead of the content. Sometimes I get too excited with the gift wrapping and not the gift. :)

It would be interesting to guess what Copernicus would say to the principle of his name. My guess is he would not like it. There is nothing so far to suggest that we are not unique in this universe in some way. Even if other sentient beings are out there, religion still has agrument for some uniqueness.

George
2008-May-29, 03:29 PM
So, as of now, regarding our position in the universe, we are much like astronomers in the mid-19th Century who still could not determine where we were located within our own galaxy. Our position near an outer edge of our galaxy was not figured out until early in the 20th Century. There is a big difference between then and now. There limitations were on their telescope capabilities; Galileo knew this. We are limited to boundaries; one being the distance and time of that seen in the CMBR. There is a strong case with BBT that we won't be seeing much beyond this limitation.

Sam5
2008-May-29, 03:33 PM
There is a big difference between then and now. There limitations were on their telescope capabilities; Galileo knew this. We are limited to boundaries; one being the distance and time of that seen in the CMBR. There is a strong case with BBT that we won't be seeing much beyond this limitation.


Yes, I realize that. We might forever be stuck in such a situation whereby our universe is so large (and, perhaps, expanded so rapidly) we might not be able to see the full extent of the overall size of the universe because of our own visual restrictions of look-back time and look-out distance. I hope that doesn't turn out to be the case. That sure would be an irritating situation.

George
2008-May-29, 08:17 PM
I suppose we can't complain if we are blessed with a backyard that measures more than 80 billion trillion miles, and a front yard just as big. :)

Cougar
2008-Jun-04, 02:59 PM
Prior to the Copernican Revolution, the Sun, Moon, and 5 planets were in the "Heavens," and the Earth was obviously not. This had major religious implications, not to mention implications for physical motion. Copernicus unified the Earth with the planets. Unification really changes things!

George
2008-Jun-04, 04:27 PM
I would agree but on the basis that unification was inferred; there was no requirement to remove the perfection of the celestial bodies within the heavenly aether, which had been established by Aristotle.

But, this inference was part of the polemic. It appears that of the problem observations of Galileo, which diminished the likelihood of the dogmatic Aristotle/Ptolemy/Aquinas model, the imperfections found on the Moon may have had a greater negative impact upon the Church views more so than the moons of Jupiter, lobes of Saturn, or sunspots. Of course, soon the complete set of phases of Venus were discovered, but the Jesuit scholars were quick to adopt the Tychonian model, which allowed heavenly perfections and explained the phases. Copernicus, however, had much greater elegance, and had no evidence agaist the akward Tychonian model. Worse, the lack of evidence for stellar parallax was a strong argument against Copernicus and his bulldog, Galileo.

crosscountry
2008-Jun-04, 05:14 PM
wouldn't they also have to prove Einstein wrong?



I make it a point not to disagree with Einstein about gravity.

parallaxicality
2008-Jun-04, 07:32 PM
On the grandest of scales then, do we need the Copernican principle? As an article of faith, is it required for science to function, like uniformity?

Cougar
2008-Jun-05, 02:51 PM
I make it a point not to disagree with Einstein about gravity.

A wise qualification.

hhEb09'1
2008-Jun-05, 03:19 PM
On the grandest of scales then, do we need the Copernican principle? As an article of faith, is it required for science to function, like uniformity?In the sense of the OP? No, we don't. That's what they are trying to test.
wouldn't they also have to prove Einstein wrong?Not in the sense of the OP, which is just an observation akin to our off-center position in the Milky Way. Not every external observation has to be symmetric, nor does it have to be symmetric.

suyuti
2008-Jun-05, 05:16 PM
Now it depends on what they mean by "special".
If it means the conditions of Earth(as in its gravitational strength, size, relation to the moon, sun etc) then it is very special although not unique(but very rare).
But in terms of it being the centre of the universe or galaxy, i don't think so.

AndreasJ
2008-Jun-05, 06:01 PM
It appears that of the problem observations of Galileo, which diminished the likelihood of the dogmatic Aristotle/Ptolemy/Aquinas model, the imperfections found on the Moon may have had a greater negative impact upon the Church views more so than the moons of Jupiter, lobes of Saturn, or sunspots.
Something I long wondered about: what did pre-Galileans think of the maria? From where I'm sitting, they'd seem obvious naked-eye imperfections.

crosscountry
2008-Jun-05, 07:19 PM
In the sense of the OP? No, we don't. That's what they are trying to test. Not in the sense of the OP, which is just an observation akin to our off-center position in the Milky Way. Not every external observation has to be symmetric, nor does it have to be symmetric.

nor does it .....



The Copernican Principle didn't say anything about space beyond the solar system. How could observations of the CMB prove it right? Only that the earth is center of something much larger.

George
2008-Jun-05, 07:38 PM
Something I long wondered about: what did pre-Galileans think of the maria? From where I'm sitting, they'd seem obvious naked-eye imperfections. That's a question I've wondered about, too. My guess is that a little color variation in an object was not enough to warrant an imperfection classification. Stars come in varying colors, too. But with the telescope, the imperfections were undeniable, so plausible deniability got kicked beyond the Moon. :)

hhEb09'1
2008-Jun-05, 08:15 PM
The Copernican Principle didn't say anything about space beyond the solar system. How could observations of the CMB prove it right? Only that the earth is center of something much larger.Reading the article linked to in the OP would probably explain it. The Copernican Principle, in the sense of the OP, is more general.

The details in the article would also explain that they are not looking for deviations from current physical theory--they're looking for deviations that would maybe explain other deviations.

Sam5
2008-Jun-05, 08:18 PM
Something I long wondered about: what did pre-Galileans think of the maria? From where I'm sitting, they'd seem obvious naked-eye imperfections.

I don’t think their thinking worked that way. I think it worked in an opposite way. Everyone of course knew that many trees of the same kind had different shapes and that a lot of things in nature were not perfectly symmetrical. And that was ok. But when some of their “theorist” found something that was symmetrical or seemed so, then they would say that it represented “perfection”. And with the earth appearing to be in the “center” of things, then that represented “perfection” too. And even though the sun, moon, and the stars in the sky were not in the sky in any symmetrical manner, that did not necessarily represent “imperfection” to them.

crosscountry
2008-Jun-05, 08:56 PM
Reading the article linked to in the OP would probably explain it. The Copernican Principle, in the sense of the OP, is more general.

The details in the article would also explain that they are not looking for deviations from current physical theory--they're looking for deviations that would maybe explain other deviations.

you caught me.:whistle:

George
2008-Jun-05, 09:26 PM
The Copernican Principle didn't say anything about space beyond the solar system. How could observations of the CMB prove it right? Only that the earth is center of something much larger. I suspect this is when the Cosmological Principle is more commonly used due to the CMB isotropy observed.

I doubt Copernicus would have been that open to the Copernican Principle [not that you are suggesting this in the least] given his limited knowledge of the cosmos. It is unclear to me what prompted him to introduce his theory, but here are my ideas as to why he might have:

1) It had recently been shown that Ptolemy's model needed tweaking. A subsequent work was introduced by a mathematician (first name begins with the letter R, Rheticus perhaps). Thus, perfection was not a given.

2) Copernicus was a 12 year college graduate. Not only did he not graduate on time, but he didn't graduate with the rest of his class (unlike me). But, he was highly educated.

3) He was fluent with Greek and, apparently, may have translated the first, or one of the first, Greek books to Polish.

4) The Greek philosophies were becoming more known in the 16th century and included a variety of models related to astronomy.

5) He found several Greeks who held to a central Sun model and mentions a number of others in his de Revolutionibus.

6) He realized that as one travels outward from the Sun, that the planets have longer and longer periods. This rings the bell of elegance, not found in Ptolemy's mess of epicycles, equants, and deferents. [Later, Copernicus had to include two of these for his to work, and did not simplify the math as he hoped and claimed.]

7) A second bell of elegance rings with his model with the idea that smaller bodies are orbiting a much larger body -- the Sun.

8) His residence was far away from the religious grip of Rome, though not all that independent during the Protestant Reformation period.

9) He had numerous other arguments favoring his model over Ptolemy.

10) His ideas were novel and intriguing to scholars, including Church scholars who encouraged him to publish.

11) He knew others were wrong about the Sun since others claimed the Sun was yellow and he knew better. [Helio humor, just kiddin']

crosscountry
2008-Jun-06, 02:28 PM
There are many possible motivations it seems. Whatever the reason I'd bet he felt certain about his conclusion.

AndreasJ
2008-Jun-06, 03:00 PM
But when some of their “theorist” found something that was symmetrical or seemed so, then they would say that it represented “perfection”.
But the face of the moon was not found by theorists - it's visible and visibly asymmetrical to anyone with halfway decent eyes.

George
2008-Jun-06, 03:15 PM
But the face of the moon was not found by theorists - it's visible and visibly asymmetrical to anyone with halfway decent eyes.
What do you see as asymmetrical?

AndreasJ
2008-Jun-06, 03:21 PM
What do you see as asymmetrical?

The pattern of high and low albedo regions. The man in the moon, if you will.

hhEb09'1
2008-Jun-06, 03:21 PM
What do you see as asymmetrical?Lunar disk (http://jeffreykishner.com/lunartunes/2007/11/gemini-full-moon-november-24-2007.html)

ETA: warning, astrological content therein

George
2008-Jun-06, 06:26 PM
The pattern of high and low albedo regions. The man in the moon, if you will. Yes, of course. I misread your post, sorry.

Sam5
2008-Jun-06, 06:53 PM
But the face of the moon was not found by theorists - it's visible and visibly asymmetrical to anyone with halfway decent eyes.

Ok, my sentence wasn’t worded properly. Perhaps I should have said that, “When something was noticed in nature (by everyone) to be asymmetrical, the theorist would often NOT use it as an example of ‘perfection’, but when something was noticed to be symmetrical, then they would say it represented ‘perfection’.”

I think this is a common trait among a lot of people of various ideological and philosophical beliefs.

Sam5
2008-Jun-06, 06:59 PM
What do you see as asymmetrical?


Interesting question. Actually, the moon exhibits circular symmetry but pattern asymmetry, something like a combination of certain kinds of symmetrical and asymmetrical art nouveau:

http://www.artshole.co.uk/arts/artists/Enara%20Uribarren/Art-Nouveau-Apple-Advert.jpg

Here is an example of symmetrical art nouveau:

http://imagecache2.allposters.com/images/pic/ARC/AN1~Art-Nouveau-Designs-Posters.jpg

And here is an example of asymmetrical art nouveau:

http://www.affordable-interiors.co.uk/images/Art%20Nouveau%20irises.jpg

tdvance
2008-Jun-09, 05:33 PM
The problem could be that, at least I learned in school, sunspots were a tough sell because they implied blemishes on the face of the sun. However, the "blemishes" on the moon are far larger....

Kaptain K
2008-Jun-09, 05:40 PM
The problem could be that, at least I learned in school, sunspots were a tough sell because they implied blemishes on the face of the sun. However, the "blemishes" on the moon are far larger....

But not as blatant. Shades of gray do not detract from the perfection of a structurally flawless slab of marble.

Sunspots are as clear as black and white!

Sam5
2008-Jun-10, 02:30 PM
For those who would like to learn where the old geocentric idea came from, they can read Ptolemy’s “The Almagest”. That book, along with Copernicus’ famous book, “On the Revolutions of the Celestial Spheres”, are usually available at used-booksellers in a single volume:

http://www.abebooks.com/servlet/SearchResults?an=Ptolemy&ph=2&tn=The+Almagest

Of course these books were not available to everybody back in the old days, because only a very few copies of the books were available, and they were read by only a few people who were usually scholars, philosophers, and scientists.

Here is a translation of the basic opinion Ptolemy wrote 150 A.D. This section comes right after he has already said that he thinks “The Heavens Move Spherically”, meaning, he thinks the stars, moon, and sun move in the sky around the earth every day.

Ptolemy 1
http://i32.tinypic.com/2m34thx.jpg

Ptolemy 2
http://i29.tinypic.com/21niao4.jpg

Many old scholars accepted Ptolemy’s point of view for several hundred years. While we’ve all been taught to revere and almost worship the famous Library at Alexandria, we need to realize that some of the books that were stored in the library contained incorrect information about nature, and that information misled many future students and scientists (and some religious leaders) for hundreds of years.

Copernicus came along later and wrote the following text, which was published in a very limited edition in 1543. There is much more to what he wrote, but these sections represent a good summary of his opinion, including his opinion about the sun being in the center of the universe, as the universe was seen from earth at that time, before the age of telescopes:

Copernicus 1:
http://i32.tinypic.com/20frre9.jpg

Copernicus 2:
http://i31.tinypic.com/2ldk7rq.jpg

Copernicus 3:
http://i26.tinypic.com/ap379.jpg

Copernicus 4:
http://i26.tinypic.com/282lumr.jpg

crosscountry
2008-Jun-12, 05:38 PM
Many old scholars accepted Ptolemy’s point of view for several hundred years. While we’ve all been taught to revere and almost worship the famous Library at Alexandria, we need to realize that some of the books that were stored in the library contained incorrect information about nature, and that information misled many future students and scientists (and some religious leaders) for hundreds of years.


Aristotle is the one that gets on my nerves the most. Man did he screw it up for future generations.

George
2008-Jun-12, 06:05 PM
Aristotle is the one that gets on my nerves the most. Man did he screw it up for future generations. Things did get out of hand, but had Aristotle himself been around in the 16th century, he probably would have agreed with Copernicus or Galileo (17th), depending how hard-headed he may have been. Many of the Church scholars favored Galileo, including the Pope, but, as I said, things got out of hand.

The real problem was the integration of Aristotle into theology, thanks primarily to Aquinas. I don't think he should be blamed, either, due to the circumstances. The Aristotle/Ptolemy/Thomist model became dogma at a time when dogma was needed to carry a lot of abnormal weight, due to the Reformation. I think this is true, but I'm no historian on Church history.

This history, however, is very applicable to today, except the powers are reversed; science holds the populace (Western Culture) more so than any religious group that opposes them. This makes things more difficult for them.

Kaptain K
2008-Jun-12, 06:06 PM
Aristotle is the one that gets on my nerves the most. Man did he screw it up for future generations.

It's not his fault that everybody took his word to be unquestioned (and unquestionable) Truth.

crosscountry
2008-Jun-12, 08:36 PM
Both of you make good points, and it is true that Aristotle didn't know his ideas would hold for so long. And I suppose had he known he was wrong he would have changed.

But there is no denying that he wanted people to believe him and even created the process of thought that was followed for so long. Actually, it may not have been the process (which we know today is seldom practical) but his conclusions alone that caused all the trouble. Once he died there were few people willing to change the dogma.



And George, regarding the religion of today, science, it changes as needed - when new evidence comes around. We often want things to switch immediately, especially in the world we live in today. But scientific revolutions don't occur overnight, and something you may find problems with can and probably will be changed. Usually at least one generation is required, but as we say with Aristotle's ideas several centuries weren't even enough.

Sam5
2008-Jun-12, 08:40 PM
It's not his fault that everybody took his word to be unquestioned (and unquestionable) Truth.

Although I said that a lot of the science books at the Library of Alexandria were “wrong”, I didn’t mean to imply that the scientists and “philosophers” who wrote them were at fault.

I think the big problem in the old days was simply the lack of communication, and the lack of the printing press, which meant that all books had to be hand-written and not many copies of them were available, plus, not many people could read.

Scientists back then were often limited to only one or two other guys in the city they lived in who they could talk to about these complex and mysterious matters. And sometimes they had to travel all the way to Alexandria just to read a few books, and many of those books had been written hundreds of years earlier, and in various languages.

So, information, ideas, and knowledge spread very slowly back in the time of the ancient Greeks and Egyptians. Plus, there were different languages and different types of written languages.

George
2008-Jun-12, 09:25 PM
But there is no denying that he wanted people to believe him and even created the process of thought that was followed for so long. Actually, it may not have been the process (which we know today is seldom practical) but his conclusions alone that caused all the trouble. Once he died there were few people willing to change the dogma. That's a good point. Aristotle was the man for quite a while. It took the insight of Copernicus and others to awaken to new ideas. [There were some new things that developed in the Arabian countries which carried forth the Greek works and reintroduced them to Europe around the 12th century. It was some of the Greek ideas, including heliocentricity, that Copernicus sought and found that helped his theory.]


And George, regarding the religion of today, science, it changes as needed - when new evidence comes around. We often want things to switch immediately, especially in the world we live in today. But scientific revolutions don't occur overnight, and something you may find problems with can and probably will be changed. Usually at least one generation is required, but as we say with Aristotle's ideas several centuries weren't even enough. That is fair explanation of the process. Today, IMO, science has earned the respect that makes some religious claims look silly. Science could flip upside down someday, but, till then, if one weighs all the facts then reason clearly dictates that certain religious claims are extremely unlikely. They are so extreme that they are "silly", thus this impacts, sadly, how others see the validity of their entire faith.

The Copernican Principle (someone should do a thread on this principle ;) ) is one such scientific idea that serves as an example of what I'm saying. It is not the bigger topic in contention with religion, however.

Disinfo Agent
2008-Jun-14, 02:10 PM
Own a piece of heliocentrism. (http://www.badastronomy.com/bablog/2008/06/12/own-a-piece-of-heliocentrism/) ;)

On Aristotle: I am not his biggest fan, although I would say an admirable thing about him -- well, two -- were his interest in natural science, and his encyclopedism. A lot of what we know about ancient Greek thinkers, we know through Aristotle. But, like George, I think the blind devotion to old Aristo in Galileo's day was more a symptom of the times, of the social climate during the Reformation and the Counter-Reformation, than any sort of cause. People had simply become intolerant (again). Rather than looking for some historical figure we can blame it all on, we should take it as a cautionary tale.

hhEb09'1
2008-Jun-14, 03:25 PM
And George, regarding the religion of today, science, it changes as needed - when new evidence comes around. We often want things to switch immediately, especially in the world we live in today. But scientific revolutions don't occur overnight, and something you may find problems with can and probably will be changed. Usually at least one generation is required, but as we say with Aristotle's ideas several centuries weren't even enough.I'm getting a little tired of some of the changes :)

Nutritional recommendations nowadays look like they have a half-life of 6.753 years, until they're reversed completely :)

George
2008-Jun-14, 05:19 PM
Nutritional recommendations nowadays look like they have a half-life of 6.753 years, until they're reversed completely :) There can be a fine line between science and marketing. :)

hhEb09'1
2008-Jun-14, 06:22 PM
There can be a fine line between science and marketing. And a gulf :)

But I was talking about things like when we gave up coffee twenty years ago because of breast tumor concerns, and now coffee is touted as something that holds off alzheimers. I think I remember studies supporting both--if I could remember who did them we could sue, if I could remember my lawyer's name.

And don't get me started on the prone-infant/back-to-sleep flip-flop.

George
2008-Jun-14, 08:41 PM
Yep. I wonder which round of flip-flop we're on. I think there use to be coke in Coca-cola, radioisotopes in toothpaste, mercury light switches, etc. So did the proverbial pendulum swing the other way and now its coming back.

I'm just glad chocolate (dark chocolate) is now a good thing. :)

Centaur
2008-Jun-23, 04:50 AM
Kinematically, one could define anything as the center of the universe, even the tip of one's nose, and not be wrong. In fact, the universe is assumed not to have a physical center, so we are free to choose any point as the center of a coordinate system.

Now if we’re talking about the solar system as a closed system, then finding its center is a different matter. First we have a linguistic problem, since the term solar system originally referred to a method for predicting the positions of planets and not the collective name for a set of objects. The term was synonymous with heliocentric system and opposed to the geocentric system.

It turns out that if we consider the Sun to be at (or near) the center of the local neighborhood of celestial bodies, the rules (Newton called them axioms or laws) of physics as related to celestial mechanics become much simpler than if we assume the Earth is at the center. Occam's Razor advises us to go with simplicity. But at a smaller scale it’s actually simpler to consider the Earth to be the center (or even your location on it) such as when predicting the path of a cannonball. In that case, assuming the Sun is at the center of the chosen coordinate system would make the calculations ridiculously complicated.

George
2008-Jun-23, 02:58 PM
Kinematically, one could define anything as the center of the universe, even the tip of one's nose, and not be wrong. Yes, GR supports this, as I understand. But this mandates that there is no absolute center, contrary to the view found in Geocenctrism. [The capital "G" refers to the absolute center tenet as opposed to geocentrism which makes no such claim.]