Planck Length
The Planck length is the smallest meaningful unit of length in physics, representing a fundamental scale at which classical ideas about gravity and space-time break down and quantum effects dominate.
It is defined as approximately 1.616 × 10⁻³⁵ meters.
The Planck length is derived from fundamental constants: the speed of light, Planck’s constant, and the gravitational constant.
It sets a theoretical limit below which the very concepts of space and distance may lose conventional meaning.
Used mainly in theories of quantum gravity and string theory.
Key facts:
1 Planck length ≈ 1.616 × 10⁻³⁵ m
Smallest scale in quantum physics and cosmology
Represents a scale where quantum effects of gravity become significant
The Planck length is crucial for understanding the fabric of the universe at its most fundamental level.
Picometer
A picometer (pm) is an extremely small unit of length in the metric system, equal to one-trillionth of a meter (1 pm = 10⁻¹² meters). Picometers are used to measure things on the atomic and subatomic scale, such as the size of atoms or the distance between particles in a molecule. For example, a hydrogen atom is about 50 picometers in radius. This unit is mainly used in physics, chemistry, and nanotechnology. Because it's so small, you won’t see picometers used in everyday life — they are only relevant in scientific research where ultra-precise measurements are required.