Spectrum

A spectrum (pl.: spectra or spectrums)[1] is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word spectrum was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism. As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum. It thereby became a mapping of a range of magnitudes (wavelengths) to a range of qualities, which are the perceived "colors of the rainbow" and other properties which correspond to wavelengths that lie outside of the visible light spectrum.

The spectrum in a rainbow

Spectrum has since been applied by analogy to topics outside optics. Thus, one might talk about the "spectrum of political opinion", or the "spectrum of activity" of a drug, or the "autism spectrum". In these uses, values within a spectrum may not be associated with precisely quantifiable numbers or definitions. Such uses imply a broad range of conditions or behaviors grouped together and studied under a single title for ease of discussion. Nonscientific uses of the term spectrum are sometimes misleading. For instance, a single left–right spectrum of political opinion does not capture the full range of people's political beliefs. Political scientists use a variety of biaxial and multiaxial systems to more accurately characterize political opinion.

In most modern usages of spectrum there is a unifying theme between the extremes at either end. This was not always true in older usage.

Etymologyedit

In Latin, spectrum means "image" or "apparition", including the meaning "spectre". Spectral evidence is testimony about what was done by spectres of persons not present physically, or hearsay evidence about what ghosts or apparitions of Satan said. It was used to convict a number of persons of witchcraft at Salem, Massachusetts in the late 17th century. The word "spectrum" [Spektrum] was strictly used to designate a ghostly optical afterimage by Goethe in his Theory of Colors and Schopenhauer in On Vision and Colors.

The prefix "spectro-" is used to form words relating to spectra. For example, a spectrometer is a device used to record spectra and spectroscopy is the use of a spectrometer for chemical analysis.

Physical sciencesedit

Diagram illustrating the electromagnetic spectrum

In the physical sciences, the term spectrum was introduced first into optics by Isaac Newton in the 17th century, referring to the range of colors observed when white light was dispersed through a prism.[2][3] Soon the term referred to a plot of light intensity or power as a function of frequency or wavelength, also known as a spectral density plot.

Later it expanded to apply to other waves, such as sound waves and sea waves that could also be measured as a function of frequency (e.g., noise spectrum, sea wave spectrum). It has also been expanded to more abstract "signals", whose power spectrum can be analyzed and processed. The term now applies to any signal that can be measured or decomposed along a continuous variable, such as energy in electron spectroscopy or mass-to-charge ratio in mass spectrometry. Spectrum is also used to refer to a graphical representation of the signal as a function of the dependent variable.

Biological scienceedit

Antibiotic spectrum of activity is a component of antibiotic classification. A broad-spectrum antibiotic is active against a wide range of bacteria,[4] whereas a narrow-spectrum antibiotic is effective against specific families of bacteria.[5] An example of a commonly used broad-spectrum antibiotic is ampicillin.[5] An example of a narrow spectrum antibiotic is Dicloxacillin, which acts on beta-lactamase-producing Gram-positive bacteria such as Staphylococcus aureus.[6]

In psychiatry, the spectrum approach uses the term spectrum to describe a range of linked conditions, sometimes also extending to include singular symptoms and traits. For example, the autism spectrum describes a range of conditions classified as neurodevelopmental disorders.

Mathematicsedit

In mathematics, the spectrum of a matrix is the multiset of the eigenvalues of the matrix.

In functional analysis, the concept of the spectrum of a bounded operator is a generalization of the eigenvalue concept for matrices.

In algebraic topology, a spectrum is an object representing a generalized cohomology theory.

Social scienceedit

A Nolan chart of the political spectrum using (red leftism and blue rightism) coding

In social science, economic spectrum is used to indicate the range of social class along some indicator of wealth or income. In political science, the term political spectrum refers to a system of classifying political positions in one or more dimensions, for example in a range including right wing and left wing.

Referencesedit

  1. ^ Dictionary.com Archived February 23, 2008, at the Wayback Machine. The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. (accessed: January 25, 2008).
  2. ^ OpenStax Astronomy, "Spectroscopy in Astronomy". OpenStax CNX. September 29, 2016 "OpenStax CNX". Archived from the original on February 17, 2017. Retrieved February 17, 2017.
  3. ^ Newton, Isaac (1671). "A letter of Mr. Isaac Newton … containing his new theory about light and colours …". Philosophical Transactions of the Royal Society of London. 6 (80): 3075–3087. Bibcode:1671RSPT....6.3075N. doi:10.1098/rstl.1671.0072. The word "spectrum" to describe a band of colors that has been produced, by refraction or diffraction, from a beam of light first appears on p. 3076.
  4. ^ Taber, Clarence Wilbur (1993). Thomas, Clayton L. (ed.). Taber's cyclopedic medical dictionary (Ed. 17, illustrated, 3. print ed.). Philadelphia: F. A. Davis. ISBN 978-0-8036-8313-6.
  5. ^ a b S.J. Hopkins, Drugs and Pharmacology for Nurses 12th ed., 1997 (ISBN 0-443-05249 2)
  6. ^ Miranda-Novales G, Leaños-Miranda BE, Vilchis-Pérez M, Solórzano-Santos F (2006). "In vitro activity effects of combinations of cephalothin, dicloxacillin, imipenem, vancomycin and amikacin against methicillin-resistant Staphylococcus spp. strains". Ann. Clin. Microbiol. Antimicrob. 5: 25. doi:10.1186/1476-0711-5-25. PMC 1617116. PMID 17034644.
🔥 Top keywords: Akademia e Shkencave e RPS te ShqiperiseAlexandria Ocasio-CortezBilderberg GroupCristiano RonaldoDong XiaowanMinecraftOperation GladioPrimal cutRiot FestStrictly Come Dancing (series 7)Main PageSpecial:SearchBaike: Requested articles/Business and economics/Companies/M-SIndian Premier LeagueFrancis Scott Key Bridge (Baltimore)Baike: Featured pictures2024 Indian Premier LeagueFrancis Scott Key Bridge collapseSean CombsNicole Shanahan3 Body Problem (TV series)PornhubJoe LiebermanThe Three-Body Problem (novel)XXXTentacionCleopatraYouTubeDan SchneiderDeaths in 2024MV DaliGodzilla x Kong: The New EmpireBrian PeckPorno y heladoSunrisers HyderabadUEFA Euro 2024Shōgun (2024 miniseries)Road House (2024 film)InstagramRonna McDanielDrake BellRobert F. Kennedy Jr.Francis Scott KeyAmanda BynesViral videoRobert HanssenBaltimoreBrandon ScottDune: Part TwoADX FlorenceFacebookTartanAditi Rao HydariSoaking (sexual practice)Ruby FrankeX-Men '97Cassie VenturaSunshine Skyway BridgeSergey Brin2024 Indian general electionList of Twenty20 cricket recordsSiddharth (actor)Portal Current eventsWinnie-the-Pooh: Blood and Honey 2Kalanithi MaranThree-body problemThe Gentlemen (2024 TV series)Kim PorterChatGPTJake GyllenhaalGhostbusters: Frozen EmpireWrestleMania XLKwena MaphakaPoor Things (film)2026 FIFA World Cup qualification (AFC)Dune (2021 film)United StatesWes MooreEndrick (footballer, born 2006)Maundy ThursdaySydney SweeneySolar eclipse of April 8, 2024Carol BurnettCrocus City Hall attackMadelyne PryorQuiet on Set: The Dark Side of Kids TVElin NordegrenKung Fu Panda 4SexCowboy CarterRed Eye (2005 American film)Battle of the HydaspesRyan GoslingFighter (2024 film)Eva MendesBattle of New CarthageImmaculate (2024 film)J. Robert OppenheimerArgentina national football teamShirley ChisholmTaylor SwiftLate Night with the DevilList of Indian Premier League records and statisticsRichard SerraTheo JamesNational September 11 Memorial & MuseumConor McGregorOppenheimer (film)Daniel KahnemanUEFA Euro 2024 qualifying