Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Natural System of Units

In course

PHYS-431: Quantum field theory I

The goal of the course is to introduce relativistic quantum field theory as the conceptual and mathematical framework describing fundamental interactions. ...

Description

This lecture covers the concept of natural system of units, focusing on Newton and Maxwell theories in CGS units. It explains the fundamental equations and relationships between physical quantities, such as force, energy, and momentum, in a simplified and coherent manner. The lecture delves into the significance of different units and their interplay in the context of quantum mechanics, shedding light on the creation of particles and the logical possibilities within the field. Additionally, it explores the untenable aspects of certain physical quantities and the compulsory nature of specific relationships, providing a comprehensive overview of the foundational principles governing the natural system of units.

Instructors (2)

Francesco Riva

Riccardo Rattazzi

Riccardo Rattazzi was born in Novara (Italy) in 1964. He studied physics at the University of Pisa, where he received the Laurea cum laude in 1987, and at the Scuola Normale Superiore where he received the Diploma in Scienze and carried out graduate research in theoretical physics. After having been a post-doctoral research associate at the Lawrence Berkeley Laboratory, at Rutgers University and at CERN, in 1998 Riccardo obtained a permanent research position at the Istituto Nazionale di Fisica Nucleare in Pisa. From 2001 to 2006 he was a staff member at the Theory Division of CERN. In 2006 he was appointed professor of physics at EPFL.

Official source

Ontological neighbourhood

Physics

Physical quantities: Topics in physical quantities

Related concepts (32)

Centimetre–gram–second system of units

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to cover electromagnetism. The CGS system has been largely supplanted by the MKS system based on the metre, kilogram, and second, which was in turn extended and replaced by the International System of Units (SI).

Gaussian units

Gaussian units constitute a metric system of physical units. This system is the most common of the several electromagnetic unit systems based on cgs (centimetre–gram–second) units. It is also called the Gaussian unit system, Gaussian-cgs units, or often just cgs units. The term "cgs units" is ambiguous and therefore to be avoided if possible: there are several variants of cgs with conflicting definitions of electromagnetic quantities and units. SI units predominate in most fields, and continue to increase in popularity at the expense of Gaussian units.

List of metric units

Metric units are units based on the metre, gram or second and decimal (power of ten) multiples or sub-multiples of these. The most widely used examples are the units of the International System of Units (SI). By extension they include units of electromagnetism from the CGS and SI units systems, and other units for which use of SI prefixes has become the norm.

MKS system of units

The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. The modern International System of Units (SI) was originally created as a formalization of the MKS system, and although the SI has been redefined several times since then and is now based entirely on fundamental physical constants, it still closely approximates the original MKS system for most practical purposes. By the mid-19th century, there was a demand by scientists to define a coherent system of units.

Natural units

In physics, natural units are physical units of measurement in which only universal physical constants are used as defining constants, such that each of these constants acts as a coherent unit of a quantity. For example, the elementary charge e may be used as a natural unit of electric charge, and the speed of light c may be used as a natural unit of speed. A purely natural system of units has all of its units defined such that each of these can be expressed as a product of powers of defining physical constants.

Related lectures (42)

Overview of Particle Physics and Rutherford Scattering

Covers the constituents of matter, fundamental forces, the Standard Model, natural units, and particle interaction experiments.

Plasma Collisions: Coulomb Force

Analyzes Coulomb collisions between charged particles and the conservation of energy, momentum, and angular momentum.

Power, Work, Energy MOOC: Material Point Mechanics

Explores the concepts of work, energy, and power in mechanics, emphasizing their importance in understanding mechanical systems.

Minkowski Spacetime: Systems of Units

Introduces Minkowski spacetime, 4-vectors, physical quantities, SI units, Planck units, and HEP units.

Newton's Laws: Inertia and Motion