Did the Romans know the Earth was round??

[Bill S]

Hi Bill:

I am sorry, but you are trapped in logical fallacy, your first fallacy, known as, Secundum quid.  This is a fallacy arising  .... etc., etc.

Hi Pax,

I'll go with this a little further, but don't want to drag it on too long in case others start to find it tedious.  But - either I didn't present my point clearly, or I'm not understanding yours.

As Numerianus points out, the question itself does not identify who precisely is meant by "the Romans".  Hence, I'll choose who I mean in my response.  I'll choose "the Roman population in general", rather than "a rare and few select Roman individuals".  And since time frame could be important, let's say 1st through 3rd century AD.   With that in mind - no, I don't think the Romans knew the solar system was heliocentric. 

You've argued that the lack of popularity of such a concept does not equal a lack of knowledge.  I believe that there was more than a lack of popularity of the concept - there was no acceptance of it among those few who may have heard of it, and very few people who had ever heard of it.  And hence the concept was not promoted or presented to the general public, not taught to students, not a commonly accepted belief, not a commonly discussed idea, and not "known" by the general population.  (I'd go so far, if I can invent numbers without studies to back them, to suggest that this includes more than 99.9% of the population.) What a population or culture "knows" is very much dependant on what it accepts as true.  What they accept as true may be incorrect, but it is still culturally "what they know."  This certainly does not negate the possibility of new ideas arising.  But the possibility that at any given time there may have been individual Romans pondering the idea of heliocentricity does not change the fact that "the Romans" (as designated above)  did not "know" the solar system was heliocentric. 

You state that simply because the masses did not accept or have access to this information first, that it did not or could not exist, ...

No, I didn't state that.  I think you interpreted into my statement something that wasn't there.  Let me clarify.  The information (Aristarchus' thoughts on heliocentricity) did exist.  Access to it does not change its existence.  But acceptance of it very much affects whether that information is disseminated.  If a body of people do not accept that information as true, and do not pass the information along to other members of the population, then the body of knowledge in that population may not include that information.  There's a big difference between saying that an unaccepted theory is documented in an archive somewhere, and "the population knows this information".  And I think that's exactly the case here.  Aristarchus' unaccepted theory was recorded in some obscure archives, but the Roman people did not "know" that the solar system was heliocentric.

And one minor point I'll add - in earlier stages of this discussion the idea that the universe is heliocentric was mentioned.  It isn't.  I have deliberately kept my references of heliocentricity to the solar system - and the Romans almost certainly didn't know there was a solar system.

[Numerianus]

I am not surprised  that some people take a stance  to be "devil's advocates" and explains that restriction of  the spread of knowledge
is for good.  My position is clear: the Catholic  church (at least, until XVI-XVII) was  the most terrible totalitarian organization.
How one can justify extermination of millions of heretics (by the way, recently, the church made an elegant move: documents were 
revealed that only a few thousands were condemned by the Inquisition, without mentioning that all others were executed along  by a procedure  triggered by this authority).  Of course, its struggle against  arians  is easy to explain (not that the cult of Soli invicto  was not just a history in IV century). The  ecclesiastic "copyright" implied that the progress was stopped for a whole millenium.
Chuch was a channel to distribute the knowledge  but which one ....

[Robert_Brenchley]

The church was never monolithic though - look at the liveliness of Medieval theological debate - and the Inquisition was never universal; the only time it was ever allowed to operate in England was specifically for the purpose of supressing the Templars. Once popular resistance gre to the point of creating breakaway peasant churches in the late Medieval period, they were completely unable to suppress them, despite persistent attempts to do so, and at times rebels had the protection of the powerful; look at Wyclif in England for instance. When they tried to arrest him, John of Gaunt's private army turned out to stop them. Eventually they had to be content with digging him up and burning his bones. I'm not saying that the desire to suppress all debate wasn't there; it undoubtedly was at times. But the means to do so were lacking, and once the invention of printing made the instant dissemination of ideas possible, revolt in northern Europe became unstoppable.

[LordBest]

Just a point about knowledge and dissemination of knowledge in Roman times, that a theory existed and had been rejected is evidence enough of dissemination and debate, the knowledge centers of the Roman world woudl have had copies in their libraries available to scholars, and the theories would have been spread and debated, even if not accepted. Thus I think it fair enough to say that some of the Roman intelligentsia knew the earth revolved around the sun etc, the knowledge was available to be re-examined if more evidence came to light or the ideas developed on, as they were under the Umayyyad Caliphate. Just my view on the subject.
                                               LordBest.

[Robert_Brenchley]

They may have speculated that the Earth revolved round the sun, but can they be said to have known? They undoubtedly had evidence available to show that the Earth was round, but did they find anything to say it went round the sun? The evidence for that is a lot harder to find; it depends on extremely close observation of the planteary motions. If that had been discovered once, it's hard to see it being lost again.

It sounds like the theory of atoms; Democritus may have proposed the idea, but evidence for their existence is something modern.

[LordBest]

Well, some of them thought they knew, and have since been proven right.
                                              LordBest.

[Numerianus]

It would be better not to evoke the atoms: it is a purely scholastic  idea, whether the procedure of devision stopped or not.
The arguments are of the same spirit  as Zenon's paradox of Achilles and the turtle.
Atom in modern sense is quite a different object/concept than that of Democritus.   It  is composed of "elementary particles"
which happened to be not so elementary.

[Robert_Brenchley]

Maybe, but I think the point stands. Merely because someone posits an idea which subsequently turns out to be true, it doesn't mean that they 'know' it to be true at the time. Depending on their particular philosophy, people might look for evidence in the study of whatever it is directly, or they might look for it in authoritative tradition, but with nothing to back the idea up, it remains nothing but an idea.

[Numerianus]

Your claim, Robert,  that the heliocentricity is a theory which is difficult to verify, might be contestable.  Unlike the existence of atoms,
the ancients could find strong evidences to support it using the astronomic techniques available to them. They could make  mesurements
of the distance to Moon and Sun as well as the diameters.  A comparison of these values with the estimate for the diameter  of Earth
gives already a pice of information.  In any case the consideration of Aristarchos were not just exercises in formal logic.
It would be interesting to get a commentary from astronomers on this issue.   

[vozmozhno]

Seeing as how my college astronomy professor just recently lectured on this subject, I'll add my two cents to the debate.

According to him, while the Greeks seriously considered the heliocentric model of the universe, they ultimately rejected it due to the lack of observable stellar parallax angles. In other words, if the Earth is moving around the sun, you should see the patterns of stars shifting accordingly in the sky as the Earth moves. They (Aristotle for instance) didn't see this and concluded therefore that the Earth doesn't move.
 
What they didn't realize is that there actually is an observable parallax angle, but it is too small to be observed by the naked eye because the stars are incredibly distant (nearest star, proxima centauri, is 4 light years or 40 trillion km from Earth). It wasn't until 1838, that Friedrich Wilhelm Bessel succeeded in measuring the parallax of a nearby star.

Even among Renaissance astronomers the debate between geocentric and heliocentric was not settled quickly. Tycho Brahe (1546-1601) developed instruments capable of making observations of the planets' positions on the Celestial Sphere accurate to within 1 arc minute, and made such observations for 20 years. Yet what conclusion did he come to? That the planets orbit the Sun, which in turn orbits the Earth!

Given such confusion, and the ability of even accurate data to be misinterpreted, I find it highly unlikely that the vast majority of Greeks, Romans and other peoples of antiquity believed anything other than that the Earth was the center of the Universe.

Voz
 

[vozmozhno]

Double checked my sources today and was surprised to learn just how far ahead of his time Aristarchus actually was.

It turns out that not only did he propose a heliocentric model, but he also accounted for the lack of stellar parallax by suggesting that the stars were indeed incredibly far away. He was absolutely right on both counts, but the same source states that his views were not widely accepted in ancient times and weren't revived until the Copernican revolution some 1800 years later. The geocentric models of Aristotle and Ptolemy were apparently much more influential in classical times than the ideas of Aristarchus.

So the point remains--the vast majority of Greeks and Romans did not know that the Earth orbits the Sun.

Voz

[Pax Orbis]

Hello:

A favorite analogy of the Athanasians: Light is
continously streaming forth from the sun. The rays of light are derived from
the sun, and not vice versa. But it is not the case that first the
sun existed and afterwards the Light. It is possible to imagine that
the sun has always existed, and always emitted light. The Light,
then, is derived from the sun, but the Light and the sun exist
simultaneously throughout eternity. They are co-eternal. Just so,
the Son exists because the Father exists, but there was never a time
before the Father produced the Son.
The analogy is further appropriate because we can know the sun only
through the rays of light that it emits. To see the sunlight is to
see the sun. Just so, Jesus says, "He who has seen me has seen the
Father." (John 14:9)
This argument used by Bishop Athanasius clearly shows he is attempting to equate Christ with the sun and the sun as focusing on the central earth.
February 8, 356 • Athanasius Exiled
Five thousand troops surrounded the church of St. Theonas in Alexandria, Egypt. Inside an all-night service had begun. Bishop Athanasius sat down and ordered a deacon to read Psalm 103. Athanasius barely escaped death this time around. The Bishop refused to leave until the people were safe. Monks seized him and dragged him from the platform. In the confusion, the monks had spirited away their venerated champion. For the third time since the Council of Nicea in 325, Athanasius went into exile.
Athanasius'  was viewed as political resistance by Arian partisans.  The Arians tried to seize control of the church and stifle Athanasius.
Bishop George, an Arian, was sent in Athanasius' place. Sixteen bishops were banished from Alexandria. George tried to force Egypt to accept a new creed in place of the Nicean. A price was placed on the head of Athanasius. But the Egyptians loyally hid their beloved teacher.
George was ousted. Athanasius returned. Twice more he was forced into exile, eventually he died peacefully. Not so George: When he returned to Alexandria, he was mobbed and killed. "
   
Eusebius, a converted Arian, author, history of first 400 yrs of the Catholic Church, Quote from Book 10
Such is the great temple (earth) which the great Creator of the universe, the Word, has built throughout the entire world, making it an intellectual image upon earth of those things which lie above the vault of heaven, so that throughout the whole creation, including rational beings on earth, his Father might be honored and adored.
Geminus
10 BC - 60 AD
Geminus wrote a number of astronomy texts, including the elementary text Isagoge or Introduction to Astronomy based on the work of Hipparchus which we referred to above. Geminus gave an historical account of earlier astronomical theories including those of Callippus and the Chaldeans. He made a significant comment on the stars, stating that:-
The main part of the work contains little mathematical astronomy. It describes the main constellations, the variation of the length of night and day at different latitudes and the length of the lunar month. The phases of the moon, solar and lunar eclipses are explained. The motion of the planets is discussed . The last chapter of Introduction to Astronomy (Chapter 18) seems rather different from the rest of the text being of a much more advanced nature.
Geminus represents observational data for the motion of the moon in longitude by means of an arithmetical function.  Geminus's mathematics text Theory of Mathematics is now lost but information about it is available from a number of sources. Proclus quotes extensively from it and Eutocius and Heron also give some information. In fact Proclus relies very heavily on the work of Geminus when he writes his own history of mathematics and it is fair to say that Geminus's books are the most valuable sources available to him.
Proclus Diadochus
Born: 8 Feb 411 in Constantinople, Byzantium
Died: 17 April 485 in Athens, Greece
His belief in many religious sayings meant that he was highly biased in his views on many issues of science. For example he mentions the hypothesis that the sun is at the centre of the planets as proposed by Hipparchus but rejects it immediately since it contradicted the views of a Chaldean whom he says that it is unlawful not to believe.
He knew they theory and rejected it.
Marinus of Neapolis
Born: about 450 in Neapolis, Palestine (called Shechem in Bible, now Nablus, Israel)
Died: about 500 in possibly Athens, Greece
When Marinus felt that Proclus was in error he was quite prepared to give his own views. For example Proclus had claimed that Plato's Parmenides was concerned with gods. Marinus, quite correctly, pointed out that Plato's work in rather concerned with 'forms'
Clearly these Romans were engaged in debate.
This post is becoming very long.  More to come.  Pax

[Robert_Brenchley]

Who's Proclus' Chaldean, if it's recorded, and is there any reason given as to why it's unlawful to disbelieve him? If you've got a reference I may well be able to track it down. On the face of it, it sounds like the old realist/nominalist debate; do we learn about a thing by examining it, or via authoritative sources which are supposed to access some external reality?

How far was Athanasius aware of the limits of his analogy? There undoubtedly was a tendency to conflate sun-worship with son-worship, but the fact that someone uses an analogy doesn't necessarily mean that he equates the two things uncritically.

[Howard Cole]

They could make  mesurements
of the distance to Moon and Sun as well as the diameters.  A comparison of these values with the estimate for the diameter  of Earth
gives already a pice of information. 

This is the first time that I have heard that the Greeks could measure the distance to the Moon and Sun, as well measure their diameters.  What is your reference for this?  I would really like to read about this, since I teach science at a community college.

Howard Cole

[Numerianus]

See, e.g. the article  to which I referred above:
http://www.fig.net/pub/cairo/papers/wshs_01/wshs01_03_lelgemann.pdf

[vozmozhno]

The article you link to makes this claim:

"It remains somewhat mysterious that modern historians such as Otto Neugebauer did not recognize that Galenus of Pergamon (129-199 A.D.) has reported in one of his many publications that Eratosthenes had provided for the distance sun/earth the value AU = 804 000 000 stadia (~10 000 earth diameter ~ 128 000 000 km), a surprisingly accurate value."

If this is true it would be noteworthy. Unfortunately, the author doesn't give a specific reference. I would like to see exactly what Galen reported about Eratosthenes. According to one online source, Eratosthenes gave 804 million stadia as the distance to the sun but also gave the moon as 780,000 stadia. If this is true he would have nearly nailed the distance to the sun (150 million km, so 85% of correct distance), while grossly underestimating the distance to the moon, which would be strange (780,000 stadia = approx. 130,000 km as opposed to moon's actual distance 380,000, so 35% of correct distance).

So far I haven't been able to find any other "reputable" sources which mention Eratosthenes and any supposed measurements of distance to the Sun and Moon. If anyone can give me a specific reference I'd be interested in investigating further.

Voz

[Pax Orbis]

Hello Robert, et al,

As requested, more information, pertaining to Proculus. 

PROCLUS DIADOCHUS

Proclus, who was born in Constantinople, studied at Plato's Academy under Plutarch and Syrianus (a pupil of Plutarch). After studying, Proclus became a teacher, and at the death of Syrianus, became head of the Academy. He was then called by the title Diadochus, meaning successor. He remained at the head of the Academy until his death. His philosophy was the neoplatonism of Plotinus, Porphyry and Iamblichus. Seven of his hymns have been preserved. His Commentary on it is our major source for Euclid's Geometry.

Well cited article:

http://encyclopedia.jrank.org/PRE_PYR/PROCLUS_or_PROCULUS_AD_410_485_.html

Proculus quotes:

“This therefore is Mathematics, she reminds you of the invisible forms of the soul; she gives life to her own discoveries; she awakens the mind and purifies the intellect; she brings light to our intrinsic ideas; she abolishes oblivion and ignorance which are ours by birth.”
“On Archimedes mathematical results:] It is not possible to find in all geometry more difficult and intricate questions, or more simple and lucid explanation... No investigation of yours would succeed in attaining the proof, and yet, once seen you immediately believe you would have discovered it.”
Proculus Diadochus

Sources:
1.   Biography in Dictionary of Scientific Biography (New York 1970-1990).
2.   Biography in Encyclopaedia Britannica.
Books:
3.   W Beierwaltes, Proklos (Frankfurt-am-Main, 1965).
4.   T L Heath, A History of Greek Mathematics (2 Vols.) (Oxford, 1921).
5.   O Neugebauer, A history of ancient mathematical astronomy (New York, 1975).
6.   L J Rosán, The Philosophy of Proculus (New York, 1949).
7.   S Sambursky, Proklos, Prasident der platonischen Akademie, und sein Nachfolger, der Samaritaner Marinos (Berlin, 1985).
8.   M Schmitz, Euklids Geometrie und ihre mathematiktheoretische Grundlegung in der neuplatonischen Philosophie des Proklos (Würzburg, 1997).
9.   T Whittaker, The NeoPlatonists (Cambridge, 1928).
10.   E Zeller, Die Philosophie der Griechen (Leipzig, 1921).
Articles:
11.   E Craig (ed.), Routledge Encyclopedia of Philosophy 7 (London-New York, 1998), 723-731.
12.   E J Dijksterhuis, Deux traductions de Proclus, Arch. Internat. Hist. Sci. (N.S.) 4 (1951), 602-619.
13.   F A Medvedev, Corniform angles in Euclid's 'Elements' and Proclus's 'Commentaries' (Russian), Istor.-Mat. Issled. 32-33 (1990), 20-34.
14.   G R Morrow (ed.), Proclus Appendix : Proclus' notes on definitions, postulates and axioms, in Studies on Euclid's 'Elements' (Hohhot, 1992), 235-350.
15.   A E Taylor, The philosophy of Proclus, Proc. Aristotlelian Soc. 18 (1918), 600-635.
16.   635.

All right Robert, my sources on Proclus, ask and ye shall receive.  Quid pro quo.  Postremo nemo aegrotus quidquam somniat tam infandum, quod non aliquis dicat philosophus.   Of course, another long post.  Brevis esse laboro obscurus fio.   Pax

[Robert_Brenchley]

Thanks. That's led me to a good site on Neoplatonism here: http://www.kheper.net/topics/Neoplatonism/ . Unfortunately nobody to the best of my knowledge has produced an accessible collection of Neoplatonist writings, so I can't check up the exact text.

[*Alex]

I have read the previous posts with interest. With great diligence and fortitude I have been able to condense the bulk of it into simple layman's terms.

Q: Did the Romans know the earth was round?
A: Yes.

Alex 

[Joe Sermarini]

Reminder:  Modern politics and religion are not permitted topics here.   While I personally find them to be fascinating and among my favorite subjects, that is not why this board is here and we stick to our purpose.   

[Robert Maxey]

Didn't Plato write about the universe being a series of crystal spheres nested inside of each other?  The earth being a flat surface in the inner sphere, the sun being in the next sphere out and the stars being in the next one out?  I think that these Platonic theories dovetailed into Christianity -- after all, the gospels were all originally written in Greek.

If so, could the sphere in some of the coins be that inner sphere given by Jupiter.  The inner sphere of human activity for Caesar.  Possibly suggesting that Jupiter was in charge of the rest of the universe?



And as to the mix of Pagan and Christian religions of the time, I am reminded of the Iliad, where different characters had different patron gods. Meaning your family had certain favorites and the gods had favorite humans too.  Kind of a mix and match, depending on your circumstances?  Don't some ancient roman homes have alters to different dieties?


Just riffing here.  Not sure if I know what I’m talking about.


Bob

[Retrospectator]

I'm sure many Romans knew the Earth was round. However, it seems that poor old Tacitus wasn't one of them . Here's what he said about Britain:

"The days exceed in length those of our part of the world; the nights are bright, and in the extreme north so short that between sunlight and dawn you can perceive but a slight distinction. It is said that, if there are no clouds in the way, the splendour of the sun can be seen throughout the night, and that he does not rise and set, but only crosses the heavens. The truth is, that the low shadow thrown from the flat extremities of the earth's surface does not raise the darkness to any height, and the night thus fails to reach the sky and stars."

Tacitus Agricola 12

I quote from here:http://www.fordham.edu/halsall/ancient/tacitus-agricola.html

[Numerianus]

What Tacitus had in mind, what a model, it is not clear. I consulted another transalation where instead of "earth's surface"  it was used 
"earth's circle". The comment claimed that Greek model of  the 5th century was abandoned  and the Romans (Tacitus included)  believed that
the Earth is a circle floating in the World Ocean. 
On the other hand,  it may happen that  the explanation of  Tacitus  does not contadict to the idea that the Earth is a ball. He could   deliver
in this way an information that there are no large mountains in Britain  which could  hide  Sun in its lowest position.  Of course, his knowledge in geography
was quite limited since in his description Britain  and Spain has a common border.

[Robert Maxey]

BTW, I am not saying everyone thought the world was flat.  Rather, the un-educated might have seen it that way.

Bob

[Robert_Brenchley]

Tacitus was hardly uneducated, but we don't know how far awareness of such rarified ideas had spread. The fact that a few were aware that the earth was round doesn't necessarily imply that it was common knowledge, even among the aristocracy.