{"id":11240,"date":"2021-09-04T12:50:06","date_gmt":"2021-09-04T12:50:06","guid":{"rendered":"https:\/\/www.africa-press.net\/niger\/politique\/peut-on-voyager-plus-vite-que-la-lumiere"},"modified":"2021-09-04T13:37:54","modified_gmt":"2021-09-04T13:37:54","slug":"peut-on-voyager-plus-vite-que-la-lumiere","status":"publish","type":"post","link":"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere","title":{"rendered":"Peut-on voyager plus vite que la lumi\u00e8re ?"},"content":{"rendered":"

Africa-Press<\/a> – Niger<\/a>. <\/strong><\/span>Nous sommes navr\u00e9s de briser des r\u00eaves, mais voyager plus vite que la lumi\u00e8re dans le vide (299.792.458 m\u00e8tres par seconde exactement, que l\u2019on arrondit souvent \u00e0 300.000.000 m\u00e8tres par seconde) est impossible. Le principe a \u00e9t\u00e9 \u00e9nonc\u00e9 au d\u00e9but du 20e si\u00e8cle par Albert Einstein avec sa th\u00e9orie de la relativit\u00e9 restreinte.<\/p>\n

D\u2019apr\u00e8s cette th\u00e9orie, un objet (ou une particule \u00e9l\u00e9mentaire) qui subit une acc\u00e9l\u00e9ration va acqu\u00e9rir de la masse. En acc\u00e9l\u00e9rant jusqu\u2019\u00e0 atteindre la vitesse de 300.000 kilom\u00e8tres par seconde, il aurait ainsi potentiellement une masse infinie. Or, pour qu\u2019un objet acc\u00e9l\u00e8re, il faut lui fournir de l\u2019\u00e9nergie, une \u00e9nergie d\u2019autant plus importante que l\u2019objet est lourd ! Pour atteindre ou d\u00e9passer la vitesse de la lumi\u00e8re, il faudrait donc \u00e0 cette \u00e9nergie une \u00e9nergie de plus en plus grande, jusqu\u2019\u00e0 tendre vers l\u2019infini, ce qui est impossible.<\/p>\n

Les tachyons, des particules qui font r\u00eaver<\/b><\/p>\n

Il n\u2019emp\u00eache que dans les ann\u00e9es 1960, des physiciens imaginent l\u2019existence de particules \u2013 nomm\u00e9es \u201ctachyons\u201d \u2013 qui circuleraient plus vite que la lumi\u00e8re dans le vide et auraient une \u00e9nergie qui diminue lorsque la vitesse augmente ! Les caract\u00e9ristiques \u201chors normes\u201d de ces tachyons, ainsi que l\u2019improbabilit\u00e9 de leur observation et les possibles paradoxes qu\u2019engendreraient leur existence-m\u00eame font d\u2019eux un objet d\u2019int\u00e9r\u00eat pour nombre d\u2019\u0153uvres de science-fiction, comme dans la s\u00e9rie The Flash o\u00f9 ils sont tr\u00e8s utiles pour produire de la vitesse et voyager dans le temps.<\/p>\n

Reste une question, que beaucoup d\u2019entre vous peuvent se poser : est-ce que la lumi\u00e8re acc\u00e9l\u00e8re pour atteindre sa vitesse ? Non, car les photons \u2013 les particules qui constituent la lumi\u00e8re \u2013 n\u2019acc\u00e9l\u00e8rent pas. Ils se propagent \u00e0 environ 300.000 kilom\u00e8tres par seconde (km\/s) sans acc\u00e9l\u00e9ration d\u00e8s qu\u2019ils sont \u00e9mis, tout simplement car\u2026 ils n\u2019ont pas de masse.<\/p>\n

Aller plus vite que la lumi\u00e8re\u2026 ailleurs que dans le vide !<\/b><\/p>\n

\u201cSi la vitesse de la lumi\u00e8re dans le vide est d\u2019environ 299.792 km\/s, elle n\u2019est que de 225.563 km\/s dans l\u2019eau et 200.000 km\/s dans le verre. La lumi\u00e8re peut donc \u00eatre \u201cd\u00e9pass\u00e9e\u201d dans un milieu mat\u00e9riel\u201d, explique le CEA sur son site internet. Ainsi, si une particule ne peut d\u00e9passer la vitesse de la lumi\u00e8re dans le vide, elle peut voyager plus rapidement que la lumi\u00e8re dans certains milieux ! Cette d\u00e9couverte \u00e9tonnante a \u00e9t\u00e9 r\u00e9alis\u00e9e par un physicien russe, Pavel Tcherenkov, et lui permettra d\u2019obtenir le prix Nobel de physique en 1958.<\/p>\n

Ce ph\u00e9nom\u00e8ne, nomm\u00e9 ainsi \u201ceffet Tcherenkov\u201d, permet notamment de d\u00e9tecter et d\u2019\u00e9tudier des particules cosmiques, ou encore d\u2019expliquer la lumi\u00e8re bleue des piscines de refroidissement des centrales nucl\u00e9aires. Car une particule qui d\u00e9passe la vitesse de la lumi\u00e8re provoque l\u2019\u00e9mission d\u2019une lumi\u00e8re intense et bleut\u00e9e, que l\u2019on appelle le \u201crayonnement Tcherenkov\u201d.<\/p>\n","protected":false},"excerpt":{"rendered":"

Africa-Press – Niger. Nous sommes navr\u00e9s de briser des r\u00eaves, mais voyager plus vite que la lumi\u00e8re dans le vide (299.792.458 m\u00e8tres par seconde exactement, que l\u2019on arrondit souvent \u00e0 300.000.000 m\u00e8tres par seconde) est impossible. Le principe a \u00e9t\u00e9 \u00e9nonc\u00e9 au d\u00e9but du 20e si\u00e8cle par Albert Einstein avec sa th\u00e9orie de la relativit\u00e9 […]<\/p>\n","protected":false},"author":82,"featured_media":11239,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,11,10],"tags":[55,60,472,29,163],"class_list":["post-11240","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-divers","category-homepage-french","category-toutes-les-actualites","tag-africa-press","tag-africa-press-niger","tag-lumiere","tag-niger","tag-voyager"],"yoast_head":"\nPeut-on voyager plus vite que la lumi\u00e8re ? - niger<\/title>\n<meta name=\"description\" content=\"Nous sommes navr\u00e9s de briser des r\u00eaves, mais voyager plus vite que la lumi\u00e8re dans le vide (299.792.458 m\u00e8tres par secon ...\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Peut-on voyager plus vite que la lumi\u00e8re ?\" \/>\n<meta property=\"og:description\" content=\"Nous sommes navr\u00e9s de briser des r\u00eaves, mais voyager plus vite que la lumi\u00e8re dans le vide (299.792.458 m\u00e8tres par secon ...\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\" \/>\n<meta property=\"og:site_name\" content=\"niger\" \/>\n<meta property=\"article:published_time\" content=\"2021-09-04T12:50:06+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-09-04T13:37:54+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/static.africa-press.net\/niger\/sites\/40\/2021\/09\/img-61336fa135927.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1080\" \/>\n\t<meta property=\"og:image:height\" content=\"607\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"cfeditorfr\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"cfeditorfr\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\"},\"author\":{\"name\":\"cfeditorfr\",\"@id\":\"https:\/\/www.africa-press.net\/niger\/#\/schema\/person\/2b1cf3cd81a31e3cd26889ca66d677f1\"},\"headline\":\"Peut-on voyager plus vite que la lumi\u00e8re ?\",\"datePublished\":\"2021-09-04T12:50:06+00:00\",\"dateModified\":\"2021-09-04T13:37:54+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\"},\"wordCount\":535,\"commentCount\":0,\"image\":{\"@id\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere#primaryimage\"},\"thumbnailUrl\":\"https:\/\/static.africa-press.net\/niger\/sites\/40\/2021\/09\/img-61336fa135927.jpg\",\"keywords\":[\"Africa Press\",\"Africa Press-Niger\",\"lumi\u00e8re\",\"Niger\",\"voyager\"],\"articleSection\":[\"Divers\",\"homepage-french\",\"Toutes les actualit\u00e9s\"],\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\",\"url\":\"https:\/\/www.africa-press.net\/niger\/toutes-les-actualites\/peut-on-voyager-plus-vite-que-la-lumiere\",\"name\":\"Peut-on voyager plus vite que la lumi\u00e8re ? 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