# Number of basic physical quantities

• Fe-56
In summary, there are only 4 basic physical quantities that are necessary to explain all observed phenomena in nature, including length, time, mass, and electric charge or current. This is based on the SI table, which includes 7 basic quantities, but some can be considered arbitrary and not essential to understanding natural phenomena. This is further explained in the context of Units Systems in Electromagnetism, which can be found in the article linked.

#### Fe-56

Am I right if I say that there are only 4 (and exactly 4) basic physical quantities which are enough to explain all observed phenomena in nature?
(of course I mean HOW, not why)
(for example length, time, mass and electric charge or current)

(Because the SI table for example would explain how natural phenomana work and there are 7 basic quantities in it, but luminous intensity is just human subjective perception of light energies, mole is just a natural number and temperature is just something artificial talking about velocity of particles.)

thanks

The number of basic "physical quantities" is arbitrary, and depends on your overall choice of units.
It is explained, in the context of Units Systems in Electromagnetism, at
http://arxiv.org/abs/1506.01951
This entire article may contain more than you're looking for, but your question will likely be answered in the course of your reading it.
- Neal

## What is the definition of a basic physical quantity?

A basic physical quantity is a measurable property of a physical system that can be expressed in terms of a numerical value and a unit of measurement.

## How many basic physical quantities are there?

The current standard definition of the International System of Units (SI) includes seven basic physical quantities: length, mass, time, electric current, temperature, amount of substance, and luminous intensity.

## Why are there only seven basic physical quantities?

The seven basic physical quantities were chosen based on their fundamental importance to all physical measurements. They are considered to be the building blocks of all other physical quantities.

## Can additional basic physical quantities be added to the SI in the future?

Yes, the SI is a dynamic system and can be revised and updated as needed. New basic physical quantities may be added in the future if they are deemed to be fundamental and universally applicable.

## What is the importance of understanding basic physical quantities?

Understanding basic physical quantities is essential for conducting accurate and precise measurements in all fields of science. It also allows for consistency and standardization in scientific communication and data analysis.