Petameter
A petameter (Pm) is a unit of length in the metric system, equal to 1 quadrillion meters (1 petameter = 10¹⁵ meters). This unit is extremely large and is used mainly in astronomy and theoretical physics to describe vast distances, such as those between stars or galaxies. For example, one petameter is about 105.7 light years. Since it measures such enormous distances, the petameter is not used in everyday life or common scientific applications—it’s mostly used in discussions about the scale of the universe.
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.
No conversions available for length.