Was Copernicus right?

[ToSeek]

A Test of the Copernican Principle

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]

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]

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]

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]

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]

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]

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]

http://jda.jaxa.jp/jda/v4_e.php?v_id...4&mission=4067

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

[George]

Yes, but now the Moon is flat and only with one axis.

[Jerry]

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]

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]

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/arc...mat/web_print/

http://hubblesite.org/newscenter/arc.../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]

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]

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]

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]

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]

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]

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]

wouldn't they also have to prove Einstein wrong?



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

[parallaxicality]

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]

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

A wise qualification.

[hhEb09'1]

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]

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]

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]

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]

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]

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]

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]

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.

[George]

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']