Convert Roman Actus (actus) to Planck Length (ℓₚ) instantly.
About these units
Roman Actus (actus)
The Roman actus was an ancient Roman unit of length measuring 120 Roman feet, or about 35.5 meters. It played an essential role in Roman land surveying and agriculture, forming part of the system used to organize farms, roads, and territorial divisions in the expanding Roman world. The actus helped define a square unit of land known as the actus quadratus, which was used for taxation, distribution of land to soldiers, and standardizing plots throughout Roman colonies. Surveyors relied on tools like the groma to lay out straight lines based on actus subdivisions, giving Roman lands their characteristic grid patterns. Although long obsolete, the actus provides key insights into Roman engineering, colonial administration, and agricultural policy. Many European land patterns can trace their roots back to Roman measurement practices — a testament to the enduring legacy of Roman surveying.
Planck Length (ℓₚ)
The Planck length, approximately 1.616 × 10⁻³⁵ meters, is perhaps the most conceptually profound unit in physics. It represents the scale at which classical notions of space and time cease to exist and quantum gravity effects dominate. Below this length, it is believed that spacetime becomes "foamy," subject to fluctuations predicted by quantum field theory and speculative models such as string theory. The Planck length is derived from fundamental constants: the speed of light, Planck's constant, and Newton's gravitational constant. These constants combine to yield a natural scale where both quantum mechanics and general relativity must merge into a unified theory. No experiment has ever probed distances anywhere near the Planck scale — it is many orders of magnitude smaller than even the size of protons — but it plays a crucial role in theoretical cosmology, black hole physics, and models of the early universe. The Planck length stands as a symbol of the limits of physical measurement and the frontier of fundamental physics.