Its baffling that civilisation actually went backwards after the fall of Rome. Science,technology, engineering everything went into decline.
This is a myth; population shifted away from the Med regions into comparatively under-developed central and northern Europe following the retreating ice age, and the population was already in decline before the 'fall' of the western empire; big slave labor projects like roads and bath houses were no longer feasible, but the labor shortages spurred an ongoing surge of innovations that didn't exist under the Empire, which didn't need innovation with so much slave labor available; the Roman Empire was stagnant re new science and technologies being introduced. All slave based economic systems stagnate in that way. The so-called 'Dark Ages' weren't very dark or for very long in the West, despite the rise in illiteracy and collapse of law and order.
Much new work in historical studies the last 40 years has busted the 'Dark Ages' myth; some regions were slower to progress, as is the case now, but the Catholic monasteries continued onward and upward, developing all kinds of new agricultural and engineering methods throughout the period and beyond, especially in the Netherlands and France. The Dominicans were major innovators, designing mills, inventing new cross breeds of animals and crops, and accomplishing engineering feats like draining swamps, and spreading the knowledge around through schools, such as they were in eras without printing presses and writing and books were an expensive luxury.
Many people these days think of Germany when they think of science and engineering expertise in Europe, but France had a long and brilliant history in the sciences; our earliest textbooks in America are in French, not German. German didn't start catching up with them until the late 18th and early 19th century, hence why the French got pushed back in the public memories. England and Scotland were also big innovators, but not until around the Elizabethan era and beyond.
Science and technology actually went into overdrive, not a decline, when the Empire 'collapsed'.