{"id":115,"date":"2020-07-20T21:07:02","date_gmt":"2020-07-20T19:07:02","guid":{"rendered":"http:\/\/www.cosmoespai.com\/cat\/?p=115"},"modified":"2020-07-20T21:07:02","modified_gmt":"2020-07-20T19:07:02","slug":"una-nau-que-viatja-mes-rapid-que-la-llum","status":"publish","type":"post","link":"https:\/\/www.cosmoespai.com\/cat\/una-nau-que-viatja-mes-rapid-que-la-llum\/","title":{"rendered":"Una nau que viatja m\u00e9s r\u00e0pid que la llum?"},"content":{"rendered":"\n<p>Un dia, mentre mirava la tele, el f\u00edsic te\u00f2ric mexic\u00e0 Miguel Alcubierre, es va fascinar mirant un episodi de <em>Star Trek <\/em>en el qual l\u2019<em>Enterprise<\/em> aconseguia anar a unes velocitats m\u00e9s altes que les de la llum. D\u2019alguna manera aconseguia comprimir l\u2019espai-temps que hi havia davant seu, fent que les estrelles no semblessin tant llunyanes.<\/p>\n\n\n\n<p>Llavors va tenir una idea, va agafar les equacions d\u2019Einstein i les va capgirar, invertint la l\u00f2gica habitual dels f\u00edsics te\u00f2rics. Va intentar pensar quin tipus de nau comprimiria l\u2019espai-temps davant seu i l\u2019expandiria darrere seu. Al final va donar amb una resposta molt simple: la distorsi\u00f3 de l\u2019espai-temps causada a <em>Star Trek<\/em> era una soluci\u00f3 possible al seu problema.<\/p>\n\n\n\n<p>Una astronau equipada amb l\u2019anomenat impuls d\u2019Alcubierre, que permet deformar l\u2019espai-temps davant seu, hauria d\u2019estar rodejada amb una bombolla de distorsi\u00f3, dins de la qual no hi hauria ni mat\u00e8ria ni energia, i per tant, l\u2019espai-temps dins de la bombolla estaria a\u00efllat de l\u2019espai-temps fora de la bombolla. Quan l\u2019astronau acceler\u00e9s, els seus tripulants no notarien res, potser ni se n\u2019adonarien, encara que estarien viatjant m\u00e9s r\u00e0pid que la llum.<\/p>\n\n\n\n<p>Els resultats d\u2019Alcubierre van sorprendre a la comunitat de cient\u00edfics. Tot i aix\u00ed, m\u00e9s tard, quan ja va haver publicat el seu article, els cr\u00edtics van comen\u00e7ar a assenyalar els seus punts d\u00e8bils. Tot i que la seva teoria d\u2019un viatge a m\u00e9s velocitat que la llum era molt elegant, no tenia en compte certes complicacions que podien sorgir. Si la zona dins de la bombolla de distorsi\u00f3 estava a\u00efllada de l\u2019exterior, la informaci\u00f3 no podr\u00e0 passar, i el pilot no podr\u00e0 controlar el rumb de la nau. A m\u00e9s a m\u00e9s, cal afegir el problema de crear una bombolla de distorsi\u00f3, que, per a comprimir l\u2019espai davant seu, hauria de ser alimentada per algun tipus de combustible, i aix\u00f2 significa alimentar-la amb mat\u00e8ria negativa o energia negativa.<\/p>\n\n\n\n<p>Aquest \u00e9s un altre problema, aconseguir mat\u00e8ria o energia negativa, que \u00e9s just del que no disposem. Com va demostrar Stephen Hawking amb el seu teorema general, tota soluci\u00f3 a les teories d\u2019Einstein que permeten viatjar m\u00e9s r\u00e0pid que la llum, impliquen o b\u00e9 mat\u00e8ria negativa, o energia negativa.<\/p>\n\n\n\n<p>Despr\u00e9s, els f\u00edsics van intentar calcular la quantitat de mat\u00e8ria o energia negativa que es necessitaria per a impulsar una astronau d\u2019aquest tipus. Resultats recents indiquen que, per a impulsar aquest tipus d\u2019astronau, es necessitarien unes quantitats de mat\u00e8ria negativa o energia negativa equivalents a la massa de J\u00fapiter. Aix\u00f2 vol dir que nom\u00e9s una civilitzaci\u00f3 molt avan\u00e7ada podria construir aquesta astronau, degut a les altes quantitats de mat\u00e8ria i energia negativa que es necessiten, impossibles d\u2019aconseguir per una civilitzaci\u00f3 com la nostra.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Un dia, mentre mirava la tele, el f\u00edsic te\u00f2ric mexic\u00e0 Miguel Alcubierre, es va fascinar mirant un episodi de Star Trek en el qual l\u2019Enterprise<span class=\"read-more-link\"><a class=\"read-more\" href=\"https:\/\/www.cosmoespai.com\/cat\/una-nau-que-viatja-mes-rapid-que-la-llum\/\">Continuar llegint<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":116,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":""},"categories":[6],"tags":[88,86,87,85,89],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/07\/Nau_Alcubierre.jpg?fit=720%2C405","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":965,"url":"https:\/\/www.cosmoespai.com\/cat\/com-viatjar-al-futur-sense-violar-les-lleis-de-la-fisica\/","url_meta":{"origin":115,"position":0},"title":"Com Viatjar al Futur Sense Violar les Lleis de la F\u00edsica","author":"Ferran","date":"14 de setembre de 2023","format":false,"excerpt":"La veritat \u00e9s que tots estem viatjant en el temps a cada instant! I ho fem a un ritme constant de 1 segon per segon. En un primer moment podr\u00edeu pensar que aix\u00f2 \u00e9s totalment diferent que viatjar a trav\u00e9s d\u2019una de les tres dimensions espacials a, per exemple, un\u2026","rel":"","context":"A &quot;Univers&quot;","block_context":{"text":"Univers","link":"https:\/\/www.cosmoespai.com\/cat\/category\/univers\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/09\/ViatgesTemps_Futur.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/09\/ViatgesTemps_Futur.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/09\/ViatgesTemps_Futur.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/09\/ViatgesTemps_Futur.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":959,"url":"https:\/\/www.cosmoespai.com\/cat\/que-es-la-gravetat\/","url_meta":{"origin":115,"position":1},"title":"Qu\u00e8 \u00e9s la gravetat?","author":"Ferran","date":"24 de juliol de 2023","format":false,"excerpt":"La gravetat \u00e9s una de les forces fonamentals de l\u2019univers. Fa que tornem a caure al terra quan saltem, i que n\u00favols de gas col\u00b7lapsin per formar estrelles. Durant segles la humanitat ha intentat entendre qu\u00e8 \u00e9s la gravetat. Malgrat aix\u00f2, no va ser fins que Isaac Newton va estudiar\u2026","rel":"","context":"A &quot;General&quot;","block_context":{"text":"General","link":"https:\/\/www.cosmoespai.com\/cat\/category\/general\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/07\/QueEs_Gravetat.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/07\/QueEs_Gravetat.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/07\/QueEs_Gravetat.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/07\/QueEs_Gravetat.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":763,"url":"https:\/\/www.cosmoespai.com\/cat\/quan-tardariem-en-arribar-a-lestrella-mes-propera\/","url_meta":{"origin":115,"position":2},"title":"Quan tardar\u00edem en arribar a l\u2019estrella m\u00e9s propera?","author":"Ferran","date":"15 d'octubre de 2022","format":false,"excerpt":"Deixant de banda el Sol, l\u2019estrella m\u00e9s propera a la Terra \u00e9s Proxima Centauri. Aquesta estrella pertany a un sistema estel\u00b7lar anomenat Alfa Centauri, format per 3 estrelles que orbiten les unes al voltant de les altres. De totes elles, Proxima Centauri \u00e9s la m\u00e9s propera a la Terra, a\u2026","rel":"","context":"A &quot;Estrelles&quot;","block_context":{"text":"Estrelles","link":"https:\/\/www.cosmoespai.com\/cat\/category\/estrelles\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/10\/Viatjar_EstrellaPropera.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/10\/Viatjar_EstrellaPropera.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/10\/Viatjar_EstrellaPropera.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/10\/Viatjar_EstrellaPropera.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":468,"url":"https:\/\/www.cosmoespai.com\/cat\/tot-sobre-el-coet-i-la-capsula-soyuz\/","url_meta":{"origin":115,"position":3},"title":"Tot sobre el coet i la c\u00e0psula Soyuz","author":"Ferran","date":"9 d'octubre de 2021","format":false,"excerpt":"Els coets Soyuz han estat llan\u00e7ant sat\u00e8l\u00b7lits, provisions i humans a l\u2019espai durant quasi cinc d\u00e8cades. Aquest coet est\u00e0 en funcionament des dels anys 60, quan Serguei Koroliov, el geni que va fer progressar enormement l\u2019URSS en la cursa espacial, el va dissenyar. Des de llavors, ha anat sofrint petites\u2026","rel":"","context":"A &quot;Coets&quot;","block_context":{"text":"Coets","link":"https:\/\/www.cosmoespai.com\/cat\/category\/coets\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/10\/Soyuz.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/10\/Soyuz.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/10\/Soyuz.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/10\/Soyuz.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":642,"url":"https:\/\/www.cosmoespai.com\/cat\/biografia-de-stephen-hawking\/","url_meta":{"origin":115,"position":4},"title":"Biografia de Stephen Hawking","author":"Ferran","date":"4 de juny de 2022","format":false,"excerpt":"Stephen Hawking va ser un important f\u00edsic te\u00f2ric brit\u00e0nic, que durant gran part de la seva vida va sofrir d\u2019una discapacitat motora neuronal que li impedia la mobilitat. Va n\u00e9ixer el 8 de gener de 1942 a Oxford, Anglaterra, exactament 300 anys despr\u00e9s de la mort de Galileu, que va\u2026","rel":"","context":"A &quot;General&quot;","block_context":{"text":"General","link":"https:\/\/www.cosmoespai.com\/cat\/category\/general\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":632,"url":"https:\/\/www.cosmoespai.com\/cat\/on-comenca-lespai\/","url_meta":{"origin":115,"position":5},"title":"On comen\u00e7a l\u2019espai?","author":"Ferran","date":"21 de maig de 2022","format":false,"excerpt":"Tot i semblar una preguntar senzilla, l\u2019altura en la qual comen\u00e7a l\u2019espai no est\u00e0 del tot clara, i les definicions sobre la frontera entre l\u2019atmosfera i l\u2019espai poden variar segons la font. En efecte, no hi ha un punt espec\u00edfic on acabi l\u2019atmosfera, sin\u00f3 que aquesta es va fent cada\u2026","rel":"","context":"A &quot;General&quot;","block_context":{"text":"General","link":"https:\/\/www.cosmoespai.com\/cat\/category\/general\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/05\/Comen\u00e7ament_Espai.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/05\/Comen\u00e7ament_Espai.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/05\/Comen\u00e7ament_Espai.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/05\/Comen\u00e7ament_Espai.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/115"}],"collection":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/comments?post=115"}],"version-history":[{"count":1,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/115\/revisions"}],"predecessor-version":[{"id":117,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/115\/revisions\/117"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/media\/116"}],"wp:attachment":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/media?parent=115"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/categories?post=115"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/tags?post=115"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}