우주와생명제 6 강 원소의기원
INTRODUCTION 노벨물리학상수상강연 (1978) 원소의기원 The Origin of Elements 아노펜지어스 Arno A. Penzias < 출처 > http://upload.wikimedia.org/wikipedia/commo ns/d/d0/messier_16_chandra.jpg < 출처 > http://starteachastronomy.c om/pictures/penzias.jpg
6-1 생명의원소들 (Elements of Life) 인류역사의대부분기간에있어서물질은흙, 공기, 불, 물네가지원소의다양한조합이라고생각되어왔다. Throughout most of recorded history, matter was thought to be composed of various combinations of four basic elements; earth, air, fire and water.
6-1 생명의원소들 (Elements of Life) 현대과학은이리스트를훨씬긴리스트로교체했는데, 지금알려진화학원소의종류는 100을훨씬넘는다. Modern science has replaced this list with a considerably longer one; the known chemical elements now number well over one hundred.
6-1 생명의원소들 (Elements of Life) 우리가호흡하는산소, 피에들어있는철, 원자로의우라늄등이중대부분은하늘의별들의불타는일생과그들의폭발적인죽음을통해서만들어졌다. Most of these, the oxygen we breathe, the iron in our blood, the uranium in our reactors, were formed during the fiery lifetimes and explosive deaths of stars in the heavens around us. 적혈구 헤모글로빈 엽록소
6-1 생명의원소들 (Elements of Life) 원소중에서몇가지는별이전혀 없었을때, 우주자체가태어난그 시기에만들어졌다. A few of the elements were formed before the stars even existed, during the birth of the universe itself.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 원소의기원을과학적으로제대로이해하려면우리가알수있는장소에서, 그리고지금존재하거나과거에존재했던상황에서 ( 양성자, 중성자등 ) 공통적인구성성분들이쌓여서원소들이합성되는과정을서술할수있어야 한다. The full scientific understanding of the origin of the elements requires a description of their build-up from their common component parts (e.g., protons and neutrons) under conditions known to exist, or to have existed, in some accessible place.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 일단그럴듯한합성과정이밝혀지고그때필요한조건들이결정되고나면그런핵반응이일어날수있는적당한장소를찾는일이뒤따랐다. < 출처 > http://upload.wikimedia.org/wikipe dia/commons/1/12/hans_bethe_an d_swedish_king.jpg 한스베테 (Hans Bethe) 1967 년노벨물리학상 Once plausible build-up processes were identified and the conditions they required were determined, the search for appropriate sites for the nuclear reactions followed.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 이런일은 1930년대에본격적으로시작되었지만, 1960년대말경에야만족할만한이론적틀이자리를잡았다. Although this search was begun in earnest in the nineteen thirties, it was toward the end of the nineteen sixties that the full outlines of a satisfactory theoretical framework emerged.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 이기간동안이루어진핵합성에관한과학적사고를대략살펴보면두관점사이에서오락가락한것을볼수있다. < 출처 > http://upload.wikimedia.org/wikipedia/ commons/d/d3/horsehead_nebula.jpg In the broad outlines of the relevant scientific thought during this period one can discern an ebb and flow between two views.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 첫번째관점에서는원소들은우리은하내의별들에서만들어지고바깥의공간으로뿌려져서새로운별이나행성들, 그리고우리발밑의암석을만드는데사용되었다고본다. In the first, the elements were thought to have been made in the stars of our galaxy and thrust back out into space to provide the raw material for, among other things, new suns, planets and the rock beneath our feet.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 두번째관점에따르면별이태어나기전에핵입자들의뜨거운수프가이미여러원소들로요리되었다고한다. 흔히이러한별이전의상태는팽창하는우주의뜨거운초기상황으로생각된다. In the second view, a hot soup of nuclear particles was supposed to have been cooked into the existing elements before the stars were formed. This pre-stellar state was generally associated with an early hot condensed stage of the expanding universe. < 출처 > http://www.particleadventure.org/images/historyuniverse-08.jpg
6-2 별에서? 그이전에?(Stella or Pre-stellar) 역사적으로보면 1930년대에원소합성을정량적으로체계화하려는시도가있었는데, 별에서는찾아볼수없는조건을필요로하는것으로드러났다. 에너지장벽 < 출처 > http://fc07.deviantart.net/fs22/i/2008/071/e/5/h imalaya_mountains_1_nepal_by_citizenfresh.jpg Historically, the first quantitative formulations of element build-up were attempted in the nineteen thirties; they were found to require conditions then thought to be unavailable in stars.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 그래서 1940 년대에는별이전의상태를원소생성의장소로고려하는 방향으로관심이바뀌었다. As a consequence, attention turned in the 1940 s to consideration of a pre-stellar state as the site of element formation.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 이러한노력도원하는목표를달성하지못했고, 1950년대에는별에서의원소생성으로관심이다시바뀌었다. This effort was not successful in achieving its stated goal, and in the 1950 s interest again turned to element formation in stars.
6-2 별에서? 그이전에?(Stella or Pre-stellar) 그때즈음에는그전에는있을수 없다고생각되었던다양한조건들이 별에서가능하다는사실이 받아들여졌다. Wires for simultaneous detonation of high-explosive charges. High-explosive lenses to force the mass inward. Subcritical mass of plutonium-239 Explosion drives fission material inward, increasing its density until it becomes supercritical By then the existence of a wide range of stellar conditions which had been excluded in earlier views had become accepted. 호일 < 출처 > https://upload.wikimedia. org/wikipedia/en/thumb/f/ ff/fred_hoyle.jpg/250px- Fred_Hoyle.jpg
6-2 별에서? 그이전에?(Stella or Pre-stellar) 마지막으로 1960년대에우주배경복사가발견되고이것이초기뜨거운우주에서나온복사의잔재로밝혀지면서별이전상태가다시관심을끌게되었다. Finally, the 1960 s saw a reawakened interest in the idea of a pre-stellar state at the same time that decisive observational support was given to the Big Bang universe by the discovery of cosmic microwave background radiation and its identification as the relic radiation of the initial fireball. < 출처 > http://www.bloggang.co m/data/u/upanigkit/pictur e/1271915370.jpg
6-3 빅뱅핵합성 (Big Bang Nucleosynthesis) Quark s charge is truly innovative. Up quark is two thirds positive. Down quark is one third negative. As the particles evolve Up and down quarks combined two one To make proton. They combined one to two To make neutron, too. Proton is made to carry charge distinctive. Neutron is made to carry charge suggestive. u = +2/3 d = -1/3
6-3 빅뱅핵합성 (Big Bang Nucleosynthesis) 아주온도와밀도가높은초기우주의상황에서는핵합성이일어날수없는데그이유는 100억도이상의고온에서는광자의에너지가너무높아서결합한핵입자가다시쪼개지기때문이다. 2.2 MeV Gamma ray 감마선 Deuterium nucleus 중수소 Proton Neutron 양성자중성자 Nuclear build-up cannot take place in the hottest, most condensed, state of the early universe because thermal photons at high temperatures > 10 10 K are energetic enough to break up bound particle groups.
6-3 빅뱅핵합성 (Big Bang Nucleosynthesis) 온도가 10 억도정도로떨어진 다음에야핵반응이일어날수있다. Only when the temperature has cooled to ~ 10 9 K, can nuclear reactions begin.
6-3 빅뱅핵합성 (Big Bang Nucleosynthesis) 10억도이상의복사장은전자- 양전자쌍을생성하는데, 이전자와양전자에의해중성자와양성자사이의열평형이이루어진다. The radiation field at T > 10 9 K generates electron-positron pairs which serve to maintain quasithermal equilibrium between neutrons and protons.
6-3 빅뱅핵합성 (Big Bang Nucleosynthesis) (1953 년에발표된 ) 알퍼, 폴린, 허먼의계산에따르면물질의 15% 정도가헬륨으로바뀌었다고한다. Alpher, Follin and Herman s results (1953) are chiefly marked by conversion of some 15% of the matter into helium.
6-4 별의핵합성 (Stellar Nucleosynthesis) 별에서는빅뱅우주에서만들어진헬륨과 별자체에서추가적으로만들어진헬륨이 ( 베릴륨 -8 을거쳐서 ) 탄소 -12 로바뀌고, 탄소로부터더무거운원소들이만들어진다. In stars, the cosmologically produced helium-4, together with additional amounts of helium produced by the stars themselves, is concerted (via berylium-8) into carbon- 12 from which the heavier elements are then built. Politics are for the moment. An equation is for eternity. A. Einstein 4 1 H 2 He + 2 1 e + 2 0 ν < 출처 > http://images-of-elements.com/s/sun.jpg 탄소핵질량 > 1.4 x 태양질량 6C + 2 He 8 O iron 찬드라세카한계 < 출처 > http://1.bp.blogspot.com/_w1kycnnbkoe/tfuq5ycmgii/aaaaaaaaebw/fulo TbpQGKs/s1600/orion_spinelli_c1.jpg
6-5 폭발적핵합성 (Explosive Nucleosynthesis) 대부분무거운원들의생성은무거운별의일생중마지막격렬한몇분사이에일어나는데이초신성폭발에서바깥층이우주공간으로퍼져나간다. 중성자포획 베타붕괴 중성자포획 핵분열 알파붕괴 베타붕괴 Much of the build-up of the heavier elements goes on in a few violent minutes during the life of massive stars in which their outer shells are thrown outward in supernova explosions.
6-5 폭발적핵합성 (Explosive Nucleosynthesis) Big Bang universe expand star supernova earth confined; H/He free, atom confined, fusion free interstellar molecules confined, life
Review In the beginning There was an element light, And to God s delight Hydrogen begat everything Following a scheme so bright Though chances seemed so slight.
Review There was a student At Harvard named Payne. She was not only diligent But also quite intelligent. She studied lines that stellar spectra contain In the visible domain. She proved that in stars hydrogen is the most abundant.