Guaporense

By the middle first century AD the Roman Empire appeared to be unstoppable. After they defeated Cartage, Macedon and the Seleucid kingdom they had achieved hegemonic status in the mediterranean by the mid 2nd century BCE and 100 years later, by the middle of the first century BCE most of the population in the mediterranean was under Roman control, from Syria to Spain and from Africa to Gaul. After the annexation of Egypt in 30 BCE Rome effectively controlled all the classical world (there were some kingdoms such as Armenia, that Augustus didn't conquer outright, but they were under indirect domination).

While the establishment of the empire enabled a great deal of political stability. For over 200 years, from 30 BCE to ~180 CE, the population of Roman Empire lived in peace. While there were many wars they were like the modern wars of the United States today, where the bulk of the population is not involved, as only 2% of the adult male citizens of the Empire were serving in the legions at a given point in time from Augustus to Marcus Aurelius.

The Roman Empire could easily deal with any military threat: instead of mobilizing 20% of the adult males of Italy to fight Hannibal in the Second Punic war the Empire only had to mobilize 2% of their adult males during the principate. Thanks to the huge population under their control, 70 million people or about one third of the population of the world (in proportion it is equivalent to the combined populations of US, Europe and China, today), and the vast economic resources of the mediterranean, the Roman Empire maintained very small military expenditures in proportion to their resources. Tax rates though the empire were low, less than 5% of the GDP (Roman GDP is generally estimated at 20 billion sesterces, some high end estimated put it on the 40-50 billion range while low end estimates give 10-15 billion sesterces, tax revenues consisted of 800 million sesterces, 4% of the 20 billion GDP). Military expenditures of the Roman Empire totaled 2% of GDP (450 million sesterces during the reign of Claudius), less in proportion than the USA, UK, France, China or Russia spend today on their military. But it was more than enough to defeat all the enemies that Rome faced in the 150 years from Augustus to Trajan.

Considering the past trajectory, by the middle of the first century the Roman Empire looked like it would, sooner or later, dominate the entire world like the European powers in the 19th century eventually did. Archaeological evidence points out that from 800 BCE to 50 CE the trend of economic development for the mediterranean basin was strongly positive and by the time of Augustus all the mediterranean was under Roman control, and the mediterranean was at the time the most advanced region on the planet by far. Rome was a city of 1 million, the same size as London in 1810, when London was the largest and richest city in the world, and about 10 times larger than the largest cities in high medieval Europe. Modern analysis of archaeological data shows that Roman production of lead, copper and silver was about 10 times the production of Europe in 1300 CE, when Europe was already beginning the Renaissance and had a population of 75 million.

Yet, 500 years later, by the sixth century half of the empire was gone and the other half was fighting enemies with armies smaller than those of the Republic during the Punic wars. Belisarius fought with armies of 10,000-20,000 soldiers and fleets of dozens of ships (in the battle of Sena Gallica the Romans employed only 50 ships), while in classical times the city state of Athens could send 200 warships to Syracuse with a crew to tens of thousands. Ancient civilization had lost most of it's logistical capacity as the Eastern Roman empire, controlling 10 times the population the Republic controlled during the first 2 Punic wars and dozens of times the population of the Delian league, mobilized smaller armies than the Republic and smaller fleets than the Delian league. Advances of science, technology and philosophy were much slower after the first two centuries CE than during classical and Hellenistic times. While the Polis, the base of classical civilization, mostly disappeared during late antiquity (the last reference to a Polis date to Justinian) while in the Hellenistic times and the early roman empire, many hundreds of poleis (most were democracies) existed inside the roman empire. The fact is that the Roman period, from 30 BCE to 476 CE, was a period of decline. Perhaps the greatest decline of civilization in human history.

Guaporense

Some argue that by the first century CE the Roman Empire had reached the limits of what was possible given the technology available. For all the greatness of the Empire it was still based on agriculture: they didn't use fossil fuels to supply the economy with energy. The energy needs of Roman civilization were mostly provided by organic sources that powered human and animal muscles. Also the Romans used wind and water power to power trading ships and water mills. But the bulk of the energy came from organic sources.

Europe finally managed to surpass ancient civilization during the 18th and 19th centuries though the use of fossil fuels, as they argue. While Rome failed to develop new energy technology and intensive farming consumed the ecological resources of the empire. In other words, ancient civilization and the Roman Empire fell because of ecological collapse. This is supported by data on global temperatures that show that between 200 CE and 800 CE a global colling period occurred. This process represented a decline in the total energy captured by the agricultural fields in the empire, that feed the men and the animals that powered the roman economy and society. While this cooling process forced the barbarian semi-nomads in the north to migrate south, into the Roman Empire, already weakened by the climate change. Under the pressure of barbarians and reduced ecological resources the empire declined and collapsed.

I don't buy this theory. There were some other factors of greater importance than ecological constraints over the ancient economy and society. The decline and fall of the Roman Empire and the classical civilization inside it was caused first and foremost by the Roman Empire.

Archaeological data, assembled by time periods from dateable sources show that the beginnings of the decline of the mediterranean civilization happened in the first or at least in the second century AD. Before the climate change and the migrations period. While climate change and migration helped to finish off the classical world, they weren't the decisive factors, but only additional pressures over the dying empire. By the time of Marcus Aurelius the decline was well under way, some sources show that trade may have peaked in the middle of the first century BCE, 200 years before his reign. It declined gently from Caesar to Aurelius, perhaps 10-20%. However some regions of the Empire declined much earlier, for the eastern mediterranean for instance, archaeological evidence suggests that it started to decline just as it was annexed into the empire: there are 57 datable shipwrecks found in the eastern mediterranean from 300 BCE to 1 CE, while from 1 CE to 300 there are only 32, or little more than half. The areas of the empire that developed after they were annexed were Gaul, Spain and Britain, the regions that were occupied mostly by non-civilized peoples before the Romans. The civilized areas stagnated or declined by the first century.I think that the main factor was lack of competition between states. In the today's world there are 200 states, each practices it's own social and economic policies. Some policies work and are adopted by other states, while some don't and other states don't adopt them. As result there is a process of social evolution that allows civilization to move forward. In the Roman Empire there weren't any competing states, Rome could be inefficient and corrupt for centuries before the costs were felt. While there weren't other nations to test other economic and social policies. When inflation hit the empire during the third century the economy collapsed because there weren't alternative currencies to the denarius/sestertii. When Diocletian froze prices and occupations, which effectively killed the operation of markets in the empire, there weren't other states to provide alternatives to the entrepreneurs working in the empire.

corndog36

Well, I suppose that when you are the worlds greatest superpower your people tend get fat and lazy. Complacent, apathetic, lethargic and self absorbed.

Linschoten

It lasted half a millennium, which is quite impressive really; nothing lasts for ever. Its decline cannot be explained by any single cause, any number of factors were involved.

Lord_of_Gauda

Classical civilization in the mediterranean collapsed, pridominantly due to the Roman inability to deal with mass scale population displacement/migrations of the first few centuries CE. Classical civilization flourished in other parts of Eurasia during the same timeframe.

As for slowing of the progress of the classical civilization- its to be expected: Greco-Roman world were not civilizations in the stringent sense pre 600 BCE: before that, they were to the Asian/Egyptian civilizations what the Celts were to the Romans: A collection of kingdoms based on farming and nobility but thats it. 600 BCEs onward was the age of great knowledge gained in the Greco-Roman world, predominantly with cultural & trade contact with west Asia and egypt. Through them, they discovered geometry, philosophy, architecture, sculpting, governance, etc. and developed them (for a period): some of them to hithero unknown heights.
The trajectory of the Greco-roman world from 600 BCE to 100 CE compared to the older civilizations of Asia & Egypt is similar to the trajectory of India/China in relation to the western world today. Why is India & China consistently registering 10% GDP growth rate per annum while we go giddy when we break 2% ? the answer is simple: They have much to learn, much to catch up on and a lot of development (Infrastructural and theoretical) that still needs to be done. They are closing the distance fast but its always faster to emulate than innovate. We are growing slowly (just like the Asian/Egyptian civilizations of that timeframe) because we are already at the ceiling of infrastructural & theoretical thought- we don't have anyone to emulate, our improvements come from innovation only. India & China have a lot of scope of emulating us (infrastructurally, educationally, etc), just like the Greco-Roman world of that time did. And once India-China catches up , which is inevitable (like the Greco-Roman world), their rate of growth & development will slow too and then stagnate. How they deal with the pressures on society at that point will determine if they get out of their stagnation period or collapse(which is more or less, historically the norm).

unclefred

It's the new craze to blame everything on ecological collapse. Despite thorough core studies proving the extended drought at the time of the classical Maya collapse, it gets ignored now and it's all about them overusing the natural resources. It did play a part, but without water the farming goes bad and it gets silted and dried up. Not to mention the extensive warfare.

Thessalonian

Not true. In most cases, the Greeks had the same if not more scientific knowledge compared to the Indians.

Lord_of_Gauda

As far as the 'archeological data' goes, it is disputable and i have already addressed it earlier: the inferences drawn (from such things as sunken wrecks, lead usage) etc. are sometimes outright incorrect and sometimes erroneous ( the bulk usage of lead in the Roman society was for piping. We have that on literary authority and as i demonstrated, the usage of lead in Roman world directly correlates to the rise and fall of urban trends, which has a lot to do with market saturation).

Datable shipwrecks mean nothing in their own: they can be merchant fleet, they can be military fleet. Since the ancient mediterranean world did not really differentiate between merchant and military vessels in construction principles ( merchant fleets had battering rams too- to scare off pirates), it is entirely speculative to draw economic conclusions from sunken wrecks alone. The decline of wrecks found in the mediterranean also correlates closely to the decline of the number of independent maritime polities in the mediterranean: its obvious that when Rome & carthage, Athens & Sparta, Delian League and Persia were fighting each other, there were a lot more naval engagements (and thus,wrecks) than the Pax Romana, where there are no military engagements in the Mediterranean for a few hundred years since Actium.

I agree that the collapse of the Roman empire is based on several factors- IMO, the climatological factor presenting itself as a socio-political factor (mass migrations) was the biggest contributor to it.

Lord_of_Gauda

Definitely not pre 400s BCE and definitely not post 200 CE. The period in between too, only in certain select topics, such as geometry, astrology and a few other.

Thessalonian

No. You have to add meteorology, astronomy, geography, and medicine, and basically ALL science from 600 BC to 100 BC.