What is Light?

Study Notes

Light is electromagnetic radiation that travels in straight lines, bends, and reflects under different circumstances.
It can pass through objects and cause harm or death in rare cases.
People have been pondering the nature of light throughout recorded history.

Electromagnetic radiation consists of waves that propagate through the electromagnetic field and vacuum of space at approximately 300,000 kilometers per second.
These waves have different wavelengths and frequencies, and are described across the electromagnetic spectrum.
Light can be thought of as a wave or a particle, depending on the experiment or problem.

The electromagnetic spectrum consists of different wavelengths and frequencies of electromagnetic waves, radiation, or light.
The spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, in order of increasing frequency and decreasing wavelength.
Radio waves have the longest wavelengths and lowest frequencies, while gamma rays have the shortest wavelengths and highest frequencies.

Visible light is a part of the electromagnetic spectrum, with wavelengths between 700 and 400 nanometers.
It is perceived by the human eye and brain as different colors, depending on the wavelength.
Red light has the longest wavelengths, while violet light has the shortest wavelengths.
The human eye detects and perceives different wavelengths of light as different colors, due to the absorption, reflection, and emission of light by atoms and molecules.

Many scientists and thinkers have contributed to the study of light, including Empedocles, Euclid, Lucretius, Rene Descartes, Isaac Newton, Robert Hooke, Christiaan Huygens, Joseph von Fraunhofer, Michael Faraday, Thomas Young, Albert Michelson, Edward Morley, James Maxwell, Heinrich Hertz, and Max Planck.
The debate about the nature of light has been ongoing, with some arguing it is a wave and others arguing it is a particle.

Light behaves like a wave, exhibiting interference patterns when projected on a surface through a double slit.
Light can also behave like a particle, demonstrating particle-like properties in the photoelectric effect.
Einstein proposed that light can be quantized, with a smallest unit or quanta of light called photons.

Light has many uses, including photosynthesis, navigation, and technology that utilizes and detects light outside the visible spectrum.
Radio waves and microwaves are used for signals, infrared light is used for night vision and climate tracking, ultraviolet light is used for vitamin D production, and X-rays and gamma rays are used for medical imaging and cancer treatment.
The electromagnetic spectrum can be used to detect objects in the universe, including galaxies, nebulas, black holes, supernovas, and neutron stars.

Light is electromagnetic radiation that is organized in the electromagnetic spectrum.
Visible light can be broken up into different wavelengths and frequencies, perceived as colors.
Light travels at approximately 300,000 kilometers per second in empty space, but slows down when passing through denser mediums.
Light exhibits both wave-like and particle-like properties, depending on the experiment or problem.