Convert Planck Length (ℓₚ) to Long Reed (long reed) instantly.
About these units
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.
Long Reed (long reed)
The long reed is a traditional unit of length used in Egypt and other ancient cultures, roughly equivalent to 2 cubits. It was employed in surveying, architecture, and the measurement of agricultural fields. The unit's length made it suitable for laying out longer distances with relatively few measurements, especially in river valley contexts where precision at large scales was important for irrigation and crop management. Historical records show the long reed in use for temple construction, pyramidal measurements, and land division, illustrating the practical integration of human-based units into early engineering practices.