29 noiembrie<\/b><\/p>\n
\u00a0<\/b><\/p>\n
1803 <\/b>– Se na\u0219te la Salzburg, \u00een Imperiul Habsburgic, Christian Doppler, fizician cunoscut pentru a\u0219a numitul efect Doppler.<\/p>\n
\u00cen 1842, la Praga, \u00ee\u0219i prezint\u0103 teoria prin care afirm\u0103 c\u0103 frecven\u021ba unei unde se modific\u0103 pentru orice observator care \u00ee\u0219i schimb\u0103 pozi\u021bia fa\u021b\u0103 de sursa acelei unde. <\/b>Dac\u0103 vrem s\u0103 fim ceva mai riguro\u0219i din punct de vedere \u0219tiin\u021bific, vom spune c\u0103 relativitatea efectul Doppler poate surveni din mi\u0219carea mediului, din mi\u0219carea observatorului sau din mi\u0219carea sursei undei.<\/p>\n
\u00cen cazul Teoriei Relativit\u0103\u021bii Generale, Einstein a considerat c\u0103 lumina \u0219i gravita\u021bia nu au nevoie de mediu, ele fiind ceva mai mult dec\u00e2t simple unde. Astfel, aceste \u201devenimente\u201d sunt influen\u021bate doar de diferen\u021ba de vitez\u0103 dintre observator \u0219i sursa la care ne referim.<\/p>\n
Ca s\u0103 \u00een\u021belege\u021bi o aplica\u021bie simpl\u0103 a acestui efect, asculta\u021bi sirena unei salv\u0103ri atunci c\u00e2nd v\u0103 afla\u021bi \u00eentr-o ma\u0219in\u0103 pe care o conduce\u021bi. Dumneavoastr\u0103 merge\u021bi regulamentar, cu 50 km\/h, \u00eentre punctele A \u0219i B. Din spate, vine salvarea, sursa sirenei, \u00a0cu o vitez\u0103 mai mare, s\u0103 zicem 70 km\/h. Fiecare und\u0103 sonor\u0103 consecutiv\u0103 pe care o va transmite din spatele dumneavoastr\u0103, va fi din ce \u00een ce mai aproape de ma\u0219ina pe care o conduce\u021bi. Undele, practic, se vor \u00eenghesui, vor veni mai multe \u00eentr-o unitate de timp dat\u0103, ceea ce va duce la cre\u0219terea frecven\u021bei. Noi vom percepe asta printr-un sunet de frecven\u021b\u0103 mai \u00eenalt\u0103 … Salvarea ne dep\u0103\u0219e\u0219te \u0219i \u00ee\u0219i continu\u0103 drumul c\u0103tre destina\u021bie. \u00cen acest caz, timpul \u00eentre 2 unde consecutive percepute de noi va cre\u0219te, ceea ce \u00eenseamn\u0103 o frecven\u021b\u0103 redus\u0103. Undele mai rare le vom percepe printr-un sunet de frecven\u021b\u0103 mai joas\u0103, mai aproape de bass.<\/p>\n
Formulele matematice prin care se exprim\u0103 acest efect difer\u0103 foarte mult, \u00een func\u021bie de undele la care se aplic\u0103.<\/p>\n
Vom vedea, sau mai bine zis nu vom vedea … c\u0103 frecven\u021ba observat\u0103 nu e aproape niciodat\u0103 aceea\u0219i cu frecven\u021ba transmis\u0103, mai ales \u00een cazul undelor electromagnetice, a luminii etc. De\u0219i dac\u0103 stau \u0219i m\u0103 g\u00e2ndesc mai bine, \u0219i lumina este o und\u0103 electromagnetic\u0103. \ud83d\ude00<\/p>\n
…<\/p>\n
Uneori, pentru a \u00een\u021belege fizica, trebuie s\u0103 \u00eencepem cu poezia.<\/p>\n
La steaua … de Mihai Eminescu<\/b><\/p>\n
\u00a0<\/b><\/p>\n
La steaua care-a r\u0103s\u0103rit <\/b><\/p>\n
\u00a0E-o cale-at\u00e2t de lung\u0103, <\/b><\/p>\n
\u00a0C\u0103 mii de ani i-au trebuit <\/b><\/p>\n
\u00a0Luminii s\u0103 ne-ajung\u0103.<\/b><\/p>\n
\u00a0<\/b><\/p>\n
Poate de mult s-a stins \u00een drum <\/b><\/p>\n
\u00a0\u00cen dep\u0103rt\u0103ri albastre, <\/b><\/p>\n
\u00a0Iar raza ei abia acum <\/b><\/p>\n
\u00a0Luci vederii noastre.<\/b><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/p>\n
Icoana stelei ce-a murit <\/b><\/p>\n
\u00a0\u00cencet pe cer se suie; <\/b><\/p>\n
\u00a0Era pe c\u00e2nd nu s-a z\u0103rit, <\/b><\/p>\n
\u00a0Azi o vedem, \u0219i nu e.<\/b><\/p>\n
\u00a0<\/b><\/p>\n
Tot astfel c\u00e2nd al nostru dor <\/b><\/p>\n
\u00a0Pieri \u00een noapte-ad\u00e2nc\u0103, <\/b><\/p>\n
\u00a0Lumina stinsului amor <\/b><\/p>\n
\u00a0Ne urm\u0103re\u0219te \u00eenc\u0103.<\/b><\/p>\n","protected":false},"excerpt":{"rendered":"
29 noiembrie \u00a0 1803 – Se na\u0219te la Salzburg, \u00een Imperiul Habsburgic, Christian Doppler, fizician cunoscut pentru a\u0219a numitul efect Doppler. \u00cen 1842, la Praga, \u00ee\u0219i prezint\u0103 teoria prin care afirm\u0103 c\u0103 frecven\u021ba unei unde se modific\u0103 pentru orice observator care \u00ee\u0219i schimb\u0103 pozi\u021bia fa\u021b\u0103 de sursa acelei unde. Dac\u0103 vrem s\u0103 fim ceva mai […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[585,1669],"class_list":["post-402","post","type-post","status-publish","format-standard","hentry","category-diverse","tag-christian-doppler","tag-mihai-eminescu"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=\/wp\/v2\/posts\/402","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=402"}],"version-history":[{"count":0,"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=\/wp\/v2\/posts\/402\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=402"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=402"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sergiumotreanu.ro\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=402"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}