Light

Cosma / Communication / Knowledge / Realm / Physical / Force / Electromagnetism / Light

—————————

Introduction1

Dictionary

light : electromagnetic radiation of any wavelength that travels in a vacuum with a speed of 299,792,458 meters (about 186,000 miles) per second; specifically : such radiation that is visible to the human eye. — Webster

OneLook, Free Dictionary, Wiktionary

Thesaurus

Roget’s II (Thesaurus.com), Merriam-Webster Thesaurus, Visuwords

Encyclopedia

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is the visible spectrum that is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz).

The main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the energy used by living things. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence. For example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey.

The primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarization, while its speed in a vacuum, 299,792,458 metres per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in a vacuum.

In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. Like all types of electromagnetic radiation, visible light propagates as waves. However, the energy imparted by the waves is absorbed at single locations the way particles are absorbed. The absorbed energy of the EM waves is called a photon, and represents the quanta of light. When a wave of light is transformed and absorbed as a photon, the energy of the wave instantly collapses to a single location, and this location is where the photon “arrives.” This is what is called the wave function collapse. This dual wave-like and particle-like nature of light is known as the wave–particle duality. The study of light, known as optics, is an important research area in modern physics. — Wikipedia

Optics (Eric Weisstein’s World of Physics, Wolfram Research)
Encyclopædia Britannica

Portal

Exploring the Science of Light! (Optical Society of America)

Search

Light (WolframAlpha), Optics (WolframAlpha)

———————-

Innovation

Science

Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.

Most optical phenomena can be accounted for using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation.

Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light’s particle-like properties, the light is modeled as a collection of particles called “photons”. Quantum optics deals with the application of quantum mechanics to optical systems.

Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, and medicine (particularly ophthalmology and optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fiber optics. — Wikipedia

Encyclopædia Britannica

Discovery

Scientists & Discovery, Light (Museum Victoria Australia)

Technology

How Light Works (HowStuffWorks)

————————–

Preservation

History

Optics Timeline (Optical Society of America)
A History of Light and Lighting (Bill Williams)

Quotation

Quotations Page Bartlett’s

Museum

The Museum of Optics (University of Arizona)

Library

WorldCat, Library of Congress, UPenn Online Books, Open Library

—————————

Participation

Education

Course

OER Commons: Open Educational Resources

Community

Occupation

Careers in Optics and Photonics (Optical Society of America)

Organization

International Society for Optics and Phontonics (SPIE)
Optical Society of America

News

International Society for Optics and Phontonics (SPIE)
Nature of Light (Science Daily)
Optics and Photonics News (Phys.org), Optics (Science 2.0), NPR Archives

Book

ISBNdb

Government

Document

USA.gov

———————-

Expression

Fun

We Are One Step Closer to a Lightsaber (Darren Orf, Popular Mechanics
Scientists Catch Up With Jedi in Understanding Light (Richard Adhikari, TechNewsWorld)

Poem

OEDILF: The Omnificent English Dictionary In Limerick Form

Music

Song Lyrics

returntotop


More News …

Optics.org News latest News from Optics.org


Optics News -- ScienceDaily Optics. Can light go backwards? Researchers push the limits of our understanding of light. Also see amazing new applications of light energy. Full-text, images, free.

  • Diamond mirrors for high-powered lasers
    on May 23, 2022 at 4:25 pm

    Researchers have built a mirror out of one of the strongest materials on the planet: diamond. By etching nanostructures onto the surface of a thin sheet of diamond, the research team built a highly reflective mirror that withstood, without damage, experiments with a 10-kilowatt Navy laser. In the future, the researchers envision these mirrors being used for defense applications, semiconductor manufacturing, industrial manufacturing, and deep space communications.

  • Custom 'headphones' boost atomic radio reception...
    on May 23, 2022 at 2:22 pm

    Researchers have boosted the sensitivity of their atomic radio receiver a hundredfold by enclosing the small glass cylinder of cesium atoms inside what looks like custom copper 'headphones.'

  • PFAS chemicals do not last forever
    on May 20, 2022 at 6:47 pm

    Once dubbed 'forever chemicals,' per-and polyfluoroalkyl substances, or PFAS, might be in the market for a new nickname. Adding iodide to a water treatment reactor that uses ultraviolet (UV) light and sulfite destroys up to 90% of carbon-fluorine atoms in PFAS forever chemicals in just a few hours, reports a new study led by environmental engineers. The addition of iodide accelerates the speed of the reaction up to four times, saving energy and chemicals.

  • Mixing laser- and x-ray-beams
    on May 20, 2022 at 6:46 pm

    Unlike fictional laser swords, real laser beams do not interact with each other when they cross -- unless the beams meet within a suitable material allowing for nonlinear light-matter interaction. In such a case, wave mixing can give rise to beams with changed colors and directions.

  • Superconductivity and charge density waves caught...
    on May 20, 2022 at 5:28 pm

    Scientists discover superconductivity and charge density waves are intrinsically interconnected at the nanoscopic level, a new understanding that could help lead to the next generation of electronics and computers.


Optics & Photonics News - Optics, Photonics, Physics News The latest news on Optics and Photonics

  • One step closer to making terahertz technology...
    on May 23, 2022 at 7:00 pm

    Researchers have discovered in two-dimensional conductive systems a new effect that promises improved performance of terahertz detectors.

  • Halting a wave in its tracks
    on May 23, 2022 at 5:48 pm

    Topological ideas have recently taken the center stage of modern electromagnetics. Typical topological photonic systems are based on nonreciprocal materials, a class of materials that enables asymmetric light–matter interactions. In particular, nonreciprocal platforms may support unidirectional channels that allow propagation in a given direction of space—let's say from left to right, but not the other way around. Such unidirectional guides are of key importance in optical systems because […]

  • Emulating impossible 'unipolar' laser pulses...
    on May 23, 2022 at 5:31 pm

    A laser pulse that sidesteps the inherent symmetry of light waves could manipulate quantum information, potentially bringing us closer to room temperature quantum computing.

  • Shining new light on cell membranes with improved...
    on May 23, 2022 at 5:19 pm

    Research from the lab of Matthew Lew at Washington University in St. Louis offers entirely new ways to see the very small.

  • Diamond mirrors for high-powered lasers
    on May 23, 2022 at 4:29 pm

    Just about every car, train and plane that's been built since 1970 has been manufactured using high-power lasers that shoot a continuous beam of light. These lasers are strong enough to cut steel, precise enough to perform surgery, and powerful enough to carry messages into deep space. They are so powerful, in fact, that it's difficult to engineer resilient and long-lasting components that can control the powerful beams the lasers emit. 

——–
Related

Here are links to pages about closely related subjects.

Knowledge Realm

Physical

“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

——
Notes

1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.