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Aristarchus of Samos › Who Was

Definition and Origins

by Cristian Violatti
published on 08 March 2013
Theories of Aristarchus (Konstable)


Aristarchus of Samos (c. 310 - c. 230 BCE) was an ancient Greek mathematician and astronomer from Ionia who came up with a revolutionary astronomical hypothesis. He claimed the Sun, not the Earth, was the fixed centre of the universe, and that the Earth, along with the rest of the planets, revolved around the Sun. He also said that the stars were distant suns that remained unmoved and that the size of the universe was much larger than his contemporaries believed.
This Sun-centred view of the universe is often referred to as “heliocentric”. It is fair to say that while the term heliocentric seems to be relatively adequate to classify Aristarchus view, it nevertheless fails to address the fact that Aristarchus' hypothesis had a number of additional interesting implications far beyond just a Sun-centred planetary system and a rotating Earth. In fact, a rotating Earth was already held by Heraclides Ponticus (390 BCE - 310 BCE) some time before Aristarchus and the Pythagorean tradition believed that the Earth was not the centre of the universe, but that it revolved around the “Central fire”, an imaginary body believed by them to be the actual source of the light of the universe.

HISTORICAL CONTEXT

Just like Egypt influence caused Greek mathematics to flourish a number of centuries before, the influence of Babylon had an equivalent stimulus over Greek astronomy. Alexander the Great 's opening of the East led to an exchange of ideas that had a critical input into Greek's astronomical notions. This is the context in which Aristarchus developed his theory.

THE GENERAL CONSENSUS AMONG GREEK ASTRONOMERS DURING THE TIME ARISTARCHUS LIVED WAS THAT THE UNIVERSE WAS EARTH-CENTRED.

Except for a few rare exceptions, the general consensus among Greek astronomers during the time Aristarchus lived was that the universe was Earth-centred. During the 4th century BCE, Plato and Aristotle defended the geocentric model but both philosophers did so using mostly mystical and mythical arguments. The stars and planets were carried around the Earth on spheres, arranged in a concentric fashion. Plato even described the universe as the Spindle of Necessity, attended by the Sirens and turned by the three Fates. There was little room in Plato's views for the idea of a universe governed by natural laws, since he rejected any form of determinism. In fact, the unpredictable motions of some planets (especially Mars ), were seen by Plato as proof that natural laws could not account for all the changes in the universe. Eudoxus, a student of Plato, challenged the views of his teacher by working on a more myth-free mathematical model, but the idea of concentric spheres and circular planetary motion still persisted.
Despite the general consensus on the Earth-centred model, there were a number of reasons that led some to believe that the model was not fully accurate and needed some corrections. For example, it was not possible for the geocentric model to explain either the changes in the brightness of the planets or their retrograde motions. Aristarchus' hypothesis was developed as an alternative explanation to the Earth-centred models' flaws.

DEVELOPMENT OF ARISTARCHUS HYPOTHESIS.

The only extant work of Aristarchus is called On the Sizes and Distances of the Sun and the Moon and it contains no hint of the heliocentric model. In fact, it adheres to the geocentric view. There are several possibilities for this. It could well be that, for the purpose of the works, it makes no difference which theory is adopted and, therefore, Aristarchus decided that presenting a view in contradiction to the general consensus would have been unwise. Another option would be that he may have arrived at the heliocentric view after writing this work. Some historians who have studied this matter in detail, such as Sir Thomas Heat, believe the latter. In this work, by means of careful geometrical analysis based on the size of the Earth's shadow on the moon during a lunar eclipse, Aristarchus concluded that the Sun must be much larger than the Earth. It is possible that the idea that tiny objects ought to orbit large ones and not the other way around, motivated his revolutionary ideas. Aristarchus also suspected that the stars we see in the night sky are actually nothing more than distant suns.
Aristarchus of Samos

Aristarchus of Samos

Unfortunately, Aristarchus works where the heliocentric model is presented are lost. His theories on the universe have been pieced together from later works and references. One of the most important and clear is the one mentioned by Archimedes in his book “The Sand Reckoner”:
[...] 'universe' is the name given by most astronomers to the sphere whose centre is the centre of the Earth and whose radius is equal to the straight line between the centre of the Sun and the centre of the Earth. [...] But Aristarchus of Samos brought out a book consisting of certain hypotheses, in which the premises lead to the result that the universe is many times greater than that now so called. His hypotheses are that the fixed stars and the Sun remain unmoved, that the Earth revolves about the Sun in the circumference of a circle, the Sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same centre as the Sun, is so great that the circle in which he supposes the Earth to revolve bears such a proportion to the distance of the fixed stars as the centre of the sphere bears to its surface.
(Archimedes, 1-2)

REJECTION OF ARISTARCHUS' VIEW

Some historians have suggested that Aristarchus himself may have abandoned his theory as a result of failing to reconcile it with the supposedly circular movements of the heavenly bodies, since all Greek astronomers took for granted that the orbit of all heavenly bodies had to be circular. Whether Aristarchus himself ended up rejecting his own hypothesis is not totally clear.What seems to be clear is that Hipparchus of Nicea, in all probability the greatest astronomical genius of antiquity among Greek astronomers, concluded that the geocentric model better explained the observations than did the model of Aristarchus.The only way that Aristarchus' view could stand mathematical analysis was by supposing an elliptical orbit of the Earth, and this supposition was almost a blasphemy to Greek thought. On top of this, this new model expanded the size of the universe far beyond the accepted size, which was also difficult to accept.
Aristarchus planetary model was discarded only to be rediscovered almost two millennia later during the years prior to the rise of modern science that took place during the Renaissance.

Neolithic Period › Ancient History

Definition and Origins

by Cristian Violatti
published on 02 April 2018
Barnhouse Settlement (Martin McCarthy (Tumulus))


The term Neolithic Period refers to the last stage of the Stone Age - a term coined in the late 19th century CE by scholars which covers three different periods: Palaeolithic, Mesolithic, and Neolithic. The Neolithic period is significant for its megalithic architecture, the spread of agricultural practices, and the use of polished stone tools.

CHRONOLOGY

The term Neolithic or New Stone Age is most frequently used in connection with agriculture, which is the time when cereal cultivation and animal domestication was introduced. Because agriculture developed at different times in different regions of the world, there is no single date for the beginning of the Neolithic. In the Near East, agriculture was developed around 9,000 BCE, in Southeast Europe around 7,000 BCE, and later in other regions. Even within a specific region, agriculture developed during different times. For example, agriculture first developed in Southeast Europe about 7,000 BCE, in Central Europe about 5,500 BCE, and Northern Europe about 4,000 BCE. In East Asia, the Neolithic goes from 6000 to 2000 BCE.

THE DEVELOPMENT OF NEOLITHIC CULTURE APPEARS TO HAVE BEEN A GRADUAL RATHER THAN A SUDDEN CHANGE.

Pottery is another element that makes the dating of the Neolithic problematic. In some regions, the appearance of pottery is considered a symbol of the Neolithic, but this notion makes the term Neolithic even more ambiguous, since the use of pottery does not always occur after agriculture: in Japan, pottery appears before agriculture, while in the Near East agriculture pre-dates pottery production.
All these factors make the starting point of the Neolithic somewhat fuzzy. It should be remembered that the origin of the term lies in a late 19th century CE classification system (detailed above) and we must keep in mind its limitations.

A REVOLUTION?

In order to reflect the deep impact that agriculture had over the human population, an Australian archaeologist named Gordon Childe popularized the term “Neolithic Revolution” in the 1940s CE. However, today, it is believed that the impact of agricultural innovation was exaggerated in the past: the development of Neolithic culture appears to have been a gradual rather than a sudden change. Moreover, before agriculture was established, archaeological evidence has shown that there is usually a period of semi-nomadic life, where pre-agricultural societies might have a network of campsites and live in different locations according to how the resources respond to seasonal variations. Sometimes, one of these campsites might be adopted as a basecamp; the group might spend the majority of time there during the year exploiting local resources, including wild plants: this is a step closer to agriculture. Agriculture and foraging are not totally incompatible ways of life. This means that a group could perform hunter-gatherer activities for part of the year and some farming during the rest, perhaps on a small scale. Rather than a revolution, the archaeological record suggests that the adoption of agriculture is the result of small and gradual changes.
Obsidian Tools

Obsidian Tools

Agriculture was developed independently in several regions. Since its origin, the dominant pattern in these separate regions is the spread of agricultural economies and the reduction of hunting and gathering activities, to the point that today hunting economies only persist in marginal areas where farming is not possible, such as frozen arctic regions, densely forested areas, or arid deserts.
Major changes were introduced by agriculture, affecting the way human society was organized and how it used the earth, including forest clearance, root crops, and cereal cultivation that can be stored for long periods of time, along with the development of new technologies for farming and herding such as plows, irrigation systems, etc. More intensive agriculture implies more food available for more people, more villages, and a movement towards a more complex social and political organization. As the population density of the villages increase, they gradually evolve into towns and finally into cities.

DEVELOPMENTS DURING THE NEOLITHIC

By adopting a sedentary way of life, the Neolithic groups increased their awareness of territoriality. During the 9600-6900 BCE period in the Near East, there were also innovations in arrowheads, yet no important changes in the animals hunted were detected. However, human skeletons were found with arrowheads embedded in them and also some settlements such as Jericho were surrounded with a massive wall and ditch around this time. It seems that the evidence of this period is a testimony of inter-communal conflicts, not far from organized warfare. There were also additional innovations in stone tool production that became widespread and adopted by many groups in distant locations, which is evidence for the existence of important networks of exchange and cultural interaction.
Neolithic Variscite Necklace

Neolithic Variscite Necklace

Living in permanent settlements brought new ways of social organization. As the subsistence strategies of Neolithic communities became more efficient, the population of the different settlements increased. We know from anthropological works that the larger the group, the less egalitarian and more hierarchical a society becomes. Those in the community who were involved in the management and allocation of food resources increased their social importance. Archaeological evidence has shown that during the early Neolithic, houses did not have individual storage facilities: storage and those activities linked to food preparation for storage were managed at village level. At the site of Jarf el Ahmar, in north Syria, there is a large subterranean structure which was used as a communal storage facility. This construction is in a central location among the households and there is also evidence that several rituals were performed in it.

TOWARDS THE END OF THE NEOLITHIC ERA, COPPER METALLURGY IS INTRODUCED, WHICH MARKS A TRANSITION PERIOD TO THE BRONZE AGE.

Another site in northern Syria named Tell Abu Hureyra, displays evidence for the transition from foraging to farming: it was a gradual process, which took several centuries. The first inhabitants of the site hunted gazelles, wild asses and wild cattle.Then, we see evidence of change: gazelle consumption dropped and the amount of sheep consumption rose (wild in the beginning and domesticated in the end). Sheepherding turned into the main source of meat and gazelle hunting became a minor activity. Human remains show an increase of tooth wear of all adults, which reflects the importance of ground cereal in the diet. It is interesting that once pottery was introduced, tooth wear rates decreased, but the frequency of bad teeth increased, which suggests that baked food made from stone-ground flour was largely replaced by dishes such as porridge and gruel, which were boiled in pots.

THE END OF THE NEOLITHIC

Towards the end of the Neolithic era, copper metallurgy is introduced, which marks a transition period to the Bronze Age, sometimes referred to as the Chalcolithic or Eneolithic Era. Bronze is a mixture of copper and tin, which has a greater hardness than copper, better casting properties, and a lower melting point. Bronze could be used for making weapons, something that was not possible with copper, which is not hard enough to endure combat conditions. In time, bronze became the primary material for tools and weapons, and a good part of the stone technology became obsolete, signalling the end of the Neolithic and thus, of the Stone Age.

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