Tempo de Planck. Origem: Wikipédia, a enciclopédia livre. Em física, o tempo de Planck, (tP), é a unidade de tempo no sistema de unidades naturais, conhecidos como Unidades de Planck. Neste intervalo de tempo a luz viaja, no vácuo, uma distância que define a unidade natural conhecida por comprimento de Planck.[1] A unidade recebe esse nome em referência a Max Planck, o primeiro a propô-la. O tempo de Planck é definido como: onde: é a constante de Planck reduzida G = constante gravitacional c = velocidade da luz no vácuo s é a unidade de tempo do sistema internacional, o segundo.
Os dois dígitos entre parenteses denotam o erro padrão do valor estimado. Tempo de Planck é o tempo passado sobre o Big Bang a partir do qual as implicações da teoria da relatividade geral passaram a ser válidas. Comprimento de Planck. Planck epoch. In physical cosmology, the Planck epoch or Planck era is the earliest period of time in the history of the universe, from zero to approximately 10−43 seconds (Planck time).
It is believed that, due to the extraordinarily small scale of the universe at that time, quantum effects of gravity dominated physical interactions. During this period, approximately 13.79 billion years ago, gravitation is believed to have been as strong as the other fundamental forces, and all the forces may have been unified. Inconceivably hot and dense, the state of the universe during the Planck epoch was unstable. As it expanded and cooled, the familiar manifestations of the fundamental forces arose through a process known as symmetry breaking. Theoretical ideas[edit] Experiments exploring this time[edit] See also[edit] [edit] References[edit] External links[edit]
Untitled. Grand unification epoch. The grand unification epoch ended at approximately 10−36 seconds after the Big Bang. At this point several key events took place. The strong force separated from the other fundamental forces. The temperature fell below the threshold at which X and Y bosons could be created, and the remaining X and Y bosons decayed. [citation needed] It is possible that some part of this decay process violated the conservation of baryon number and gave rise to a small excess of matter over antimatter (see baryogenesis).
This phase transition is also thought to have triggered the process of cosmic inflation that dominated the development of the universe during the following inflationary epoch. See also[edit] References[edit] Untitled. Electroweak epoch. In physical cosmology the electroweak epoch was the period in the evolution of the early universe when the temperature of the universe was high enough to merge electromagnetism and the weak interaction into a single electroweak interaction (> 100 GeV). The electroweak epoch began when the strong force separated from the electroweak interaction. Some cosmologists place this event at the start of the inflationary epoch, approximately 10−36 seconds after the Big Bang.[1][2][3] Others place it at approximately 10−32 seconds after the Big Bang when the potential energy of the inflaton field that had driven the inflation of the universe during the inflationary epoch was released, filling the universe with a dense, hot quark–gluon plasma.[4] Particle interactions in this phase were energetic enough to create large numbers of exotic particles, including W and Z bosons and Higgs bosons.
See also[edit] References[edit] Untitled. Como Funcionam as Células Nervosas. Como Funcionam as Células Nervosas. Parte II O Potencial de Ação Silvia Helena Cardoso, Luciana Christante de Mello, MSc e Renato M.E. Sabbatini, PhD Animações e ilustrações: André Malavazzi Eletricidade é um processo natural em nosso organismo e está envolvida na função específica de certas células especiais no cérebro e nos músculos estriados e lisos. Cada padrão de luz, som, calor, dor, cada piscar de olhos, estalar de dedos, cada pensamento, se traduz em uma sequência de pulsos elétricos.
Como isso acontece? As células nervosas possuem propriedades similares às outras células em muitos aspectos: elas se alimentam, respiram, passam por processos de difusão e osmose em suas membranas, etc., mas diferem em um aspecto importante: elas processam informação. A habilidade das células nervosas processarem informação depende de propriedades especiais da membrana do neurônio, a qual controla o fluxo de substâncias ao lado interno da célula (íons sódio, cálcio, potássio, etc).
O Impulso Nervoso. File:Descartes-reflex.JPG. Photosynthesis. Biological process to convert light into chemical energy Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain photosynthetic pigments or chromophores.
In plants, these proteins are chlorophyll (a porphyrin derivative that absorbs the red and blue spectrums of light, thus reflecting a green color) held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two further compounds that serve as short-term stores of energy to later drive other reactions: reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), the "energy currency" of cells.
File:Photosynthesis.gif. Segundo. Origem: Wikipédia, a enciclopédia livre. Segundo (símbolo: s, que deve ser grafado em letra minúscula, com exceção de inícios de frase, também como símbolo " ) é uma unidade de medida angular usada também para medir intervalos tempo. Originalmente, o segundo deveria ser o tempo que o sol a pino leva para percorrer a distância de 1/86400 da circunferência terrestre, ou seja, 462,962 metros na linha do equador. Em 1818, juntamente com o metro, passou a ser uma unidade padrão no Sistema Internacional de Unidades (SI). Hoje o segundo é definido tecnicamente como a duração de 9'192'631'770 períodos da radiação correspondente à transição entre dois níveis hiperfinos do estado fundamental do átomo de césio 133. Embora seja uma prática relativamente comum, a escrita do segundo com dois apóstrofos, com o objetivo de designar uma grandeza temporal e não trigonométrica, isto é, oficialmente, considerado um erro.[1] Big Ben, o relógio que é referência mundial na determinação do tempo Referências.
File:Cesium.jpg. Proton. Subatomic particle with positive charge A proton is a stable subatomic particle, symbol p, H+, or 1H+ with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than the mass of a neutron and 1,836 times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with masses of approximately one atomic mass unit, are jointly referred to as "nucleons" (particles present in atomic nuclei). One or more protons are present in the nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z).
Since each element has a unique number of protons, each element has its own unique atomic number, which determines the number of atomic electrons and consequently the chemical characteristics of the element. Description[edit] Unsolved problem in physics: . File:Cesium.jpg. Minute. By contrast to the hour the minute (and the second) has not a clear historical background. What is traceable only is that it started being recorded in the Middle ages due to the ability of construction of "precision" timepieces (mechanical and water clocks). However, no consistent records of the origin for the division as 1⁄60 part of the hour (and the second 1⁄60 of the minute) have ever been found, despite many speculations.
See also[edit] Notes and references[edit] Bibliography[edit] Henry Campbell Black, Black's Law Dictionary, 6th Edition, entry on Minute. International System of Units. Modern form of the metric system Since 2019, the magnitudes of all SI units have been defined by declaring exact numerical values for seven defining constants when expressed in terms of their SI units. These defining constants are the speed of light in vacuum, c, the hyperfine transition frequency of caesium ΔνCs, the Planck constant h, the elementary charge e, the Boltzmann constant k, the Avogadro constant NA, and the luminous efficacy Kcd. The nature of the defining constants ranges from fundamental constants of nature such as c to the purely technical constant Kcd. Prior to 2019, h, e, k, and NA were not defined a priori but were rather very precisely measured quantities.
In 2019, their values were fixed by definition to their best estimates at the time, ensuring continuity with previous definitions of the base units. Introduction[edit] Controlling body[edit] Overview of the units[edit] SI base units[edit] SI derived units[edit] Coherent and non-coherent SI units[edit] New units[edit] Photon. Nomenclature[edit] In 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy. In his 1901 article [4] in Annalen der Physik he called these packets "energy elements".
The word quanta (singular quantum) was used even before 1900 to mean particles or amounts of different quantities, including electricity. Later, in 1905, Albert Einstein went further by suggesting that electromagnetic waves could only exist in these discrete wave-packets.[5] He called such a wave-packet the light quantum (German: das Lichtquant). Physical properties[edit] The cone shows possible values of wave 4-vector of a photon. A photon is massless,[Note 2] has no electric charge,[13] and is stable. Photons are emitted in many natural processes. The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ): Experimental checks on photon mass[edit] would affect the galactic plasma.
Bacteria. Bacteria ( Most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory.[11] The study of bacteria is known as bacteriology, a branch of microbiology. Etymology Origin and early evolution Bacteria were also involved in the second great evolutionary divergence, that of the archaea and eukaryotes.
Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea.[23][24] This involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya (sometimes in highly reduced form, e.g. in ancient "amitochondrial" protozoa). Morphology Even more complex morphological changes are sometimes possible. Cellular structure Intracellular structures Extracellular structures Endospores Growth and reproduction. File:Binary Fission 2.svg. Cancel Edit Delete Preview revert Text of the note (may include Wiki markup) Could not save your note (edit conflict or other problem). Please copy the text in the edit box below and insert it manually by editing this page. Upon submitting the note will be published multi-licensed under the terms of the CC-BY-SA-3.0 license and of the GFDL, versions 1.2, 1.3, or any later version.
Add a note Draw a rectangle onto the image above (press the left mouse button, then drag and release). Save To modify annotations, your browser needs to have the XMLHttpRequest object. [[MediaWiki talk:Gadget-ImageAnnotator.js|Adding image note]]$1 [[MediaWiki talk:Gadget-ImageAnnotator.js|Changing image note]]$1 [[MediaWiki talk:Gadget-ImageAnnotator.js|Removing image note]]$1. Hora. Origem: Wikipédia, a enciclopédia livre. A hora (símbolo: h) é uma unidade de medida de tempo que tem por base a velocidade de rotação e as dimensões da Terra. Na convenção moderna uma hora é equivalente a 60 minutos ou 3 600 segundos. Isso é aproximadamente 1/24 (um vinte e quatro avos) de um dia da Terra. A hora foi originalmente definida no Egito como 1/24 (um vinte e quatro avos) de um dia, baseado no sistema de numeração duodecimal.
Apesar de não ser definido pelo Sistema Internacional de Unidades (SI), o mesmo aceita que a unidade seja representada pelo símbolo h.[1] História[editar | editar código-fonte] A hora foi definida originalmente pelas civilizações antigas (incluindo o Egito, Suméria, Índia e China) tanto como um doze avos do tempo entre o nascer e o pôr do sol ou como um vinte e quatro avos de um dia.
Diferentes definições antigas de hora: Um doze avos de tempo do nascer ao pôr do sol. Contagem das horas[editar | editar código-fonte] Ver também[editar | editar código-fonte] Mitose. Origem: Wikipédia, a enciclopédia livre. Etapas da mitose: I ao III prófase, IV metáfase, V e VI anáfase, VII e VIII telófase. Mitose (do grego mitos, fio, filamento[1] ) é o processo pelo qual as células eucarióticas dividem seus cromossomos entre duas células menores do corpo.
Este processo dura, em geral, 52 a 80 minutos e é dividido em cinco fases[Nota 1] : Prófase, prometáfase, metafase, anafase e telófase.[2] É uma das fases do processo de divisão celular ou fase mitótica do ciclo celular.[3] Definição[editar | editar código-fonte] Um dos pressupostos fundamentais e principais da biologia celular é o de que todas as células se originam a partir de células pré-existentes, à excepção do ovo ou zigoto que, nos seres vivos com reprodução sexuada, resulta da união de duas células reprodutivas (gâmetas), cada qual com metade da informação genética de seus ascendentes. Comportamento dos cromossomos na mitose[editar | editar código-fonte] Ciclo celular[editar | editar código-fonte] Referências. File:Major events in mitosis.svg. Dia. File:Rotating earth axial tiles to orbit.gif. Month. Ano.
CD-ROM - Atlas de Energia Elétrica do Brasil - 2ª edição. Solar cycle. File:The Solar Cycle XRay hi.jpg. Brasileiro nasce com esperança de vida de 74 anos e 29 dias, diz IBGE - notícias em Brasil. Carbon-14. Untitled. File:Hoploscaphites ammonite.jpg. NASA - Sun-Earth Day - Technology Through Time - #50 Ancient Sunlight. Photon. Sol. NASA - Sun-Earth Day - Technology Through Time - #50 Ancient Sunlight.
Homo sapiens. File:Christopher Columbus.PNG. File:Diagram of the human heart (cropped).svg. File:Digestive system diagram en.svg. File:Human brain NIH.png. File:Gene.png. Big Bang. Untitled. Star. File:Witness the Birth of a Star.jpg. Pangaea. File:Pangaea continents.svg. File:Pangea animation 03.gif. Galaxy formation and evolution. Untitled. History of the Earth. Stromatolite. File:Stromatolites.jpg. Age of the Earth. Sistema Solar. Ficheiro:Solarnebula.jpg.
Como nasceram as primeiras estrelas no Universo » O Universo - Eternos Aprendizes. Universo e SS (resumo) Solar System Exploration. Ficheiro:Sun Life.png. IOK-1. Press Release - Cosmic Archeology Uncovers the Universe’s Dark Ages - Subaru Telescope. Universo. May 2011. This 3-D Map Will Make Teaching the Universe a Whole Lot Cooler. Electron. File:Cyclotron motion wider view.jpg. Proton. File:Quark structure proton.svg.