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1、宇宙学宇宙的诞生、演化和结局之 4大爆炸宇宙学基本理论哈勃的发现: 哈勃定律Hubble Lawl1929年他仅用24个星系的观测数据，证实了星系 的红移（也即多普勒速度）与距离之间有“粗略的 线性关系”哈勃定律: 离我们越远的星系，远 离我们的速度越大。大爆炸宇宙学的雏形l Lematre 勒梅特 1932年提出现在的宇宙是由一 个极端高热,极端高压缩高密的原始原子大爆炸 产生-hypothesis假设 of the primeval atom原 始原子 -大爆炸宇宙学的雏形l 大爆炸宇宙论l基于1929年哈勃定律和1932年勒梅特的现 代宇宙大爆炸理论大爆炸宇宙学的雏形l1948年俄裔美国
2、科学家伽莫夫G. Gamow亚 力山大弗里德曼的学生等人运用原子核和 基本粒子物理学和宇宙膨胀联系起来,建立 了大爆炸元素形成理论-大爆炸宇宙论Big Bang.The Big Bang-大爆炸宇宙学l1948年: Russian-American physicist, George Gamow伽莫 夫, published the first model about the universe: l(1). Our Universe started from a hot and dense fireball 高 温高密的火球; l(2). About 13.7 billion years ag
3、o everything in the Universe was confined to a single point at that instant, then the point exploded, flying apart at high speeds;l(3). As it expands, the gas within it cools.-the hot Big Bang 热大爆炸.lthe Big Bang- marked the beginning of the entire Universe标志着整个宇宙的开始.lBig Bang theory (Standard Cosmol
4、ogy 标准宇宙学)宇宙的整个膨胀历史宇宙的整个膨胀历 史l 1. Prediction预言 of Big bang TheorylGamov et al proposed all chemical elements synthesized via nuclear reaction in hot early universe-Big Bang Nucleosynthesis核合成 BBNl Make 2 predictions.(1). Abundance丰度 of the light elements H, He, LilThe Big Bang theory makes definite
5、predictions for the types类型 and amount 数量of matter in the universe.宇宙的最初3分种lBBN在大爆炸之后只经历了几分钟,形成了轻元素 H, He, Li.lSteven Weinberg (born May 3, 1933) is an American physicist and Nobel laureate in Physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and
6、 electromagnetic interaction between elementary particles 弱电统一. l1977年出版: The First Three Minutes宇宙最初三分钟全球流行的科普通俗读物 Steven Weinberg (2). The cosmic microwave background radiation CMBR宇宙微波背景辐射l The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas w
7、ithin it cools. lGamov 1948 predicted this creation left behind a faint glow暗 淡的光 that suffuses the universe today, the cosmic background radiation.lThus the universe should be filled with radiation that is literally the remnant heat leftover剩余物 from the Big Bang, called the “cosmic microwave backgr
8、ound radiation”, or CMBR with a temperature of about 10K. Discovery of the Cosmic Microwave Backgroundl1964 1965: Arno Penzias and Robert Wilson using the 20-foot radio antenna at Bell Lab for their research for radio astronomy observations .lIn 1965, on building their most sensitive antenna/receive
9、r system, the pair encountered radio noise which they could not explain. It was far less energetic than the radiation given off by the Milky Way, and it was isotropic, so they assumed their instrument was subject to interference by terrestrial sources. They tried, and then rejected, the hypothesis t
10、hat the radio noise emanated from New York City. An examination of the microwave horn antenna showed it was full of pigeon droppings . After the pair removed the guano buildup, and the pigeons were shot, the noise remained. lHaving rejected all sources of interference, the pair published a paper ann
11、ouncing their findings-later identified as the cosmic microwave background radiation (CMB), the radio remnant of the Big Bang. l有力地支持了大爆炸理论，从而否定了另一个比较流行的稳恒态宇宙理论。 黑体辐射l Discovery of faint, uniform, persistent “noise噪 音” at 3K.l The discovery of CMB won Penzias and Wilson the 1978 Nobel PrizePenzias a
12、nd Wilson with their horn Shaped antenna at Bell LabPenzias and Wilson in front of the horn antenna (7.35cm) at Bell Labs lBlack body radiation黑体Robert Henry Dicke (May 6, 1916 March 4, 1997) lMeanwhile, Princeton team led by Robert Dicke was building a radio telescope to detect the big-band aftergl
13、ow predicted by Gamov.lWork on Brans-Dicke theory led Dicke to think about the early Universe, and with Jim Peebles.lDicke re-derived the prediction of a cosmic microwave background (having allegedly forgotten the earlier prediction of George Gamow and co-workers). lNaturally, Dicke, with David Todd
14、 Wilkinson and Peter G. Roll immediately set about building a Dicke radiometer to search for the radiation, but they were famously scoopedby the accidental detection made by Arno Penzias and Robert Woodrow Wilson Title: Cosmic Black-Body Radiation. Authors: Dicke, R. H., Peebles, P. J. E., Roll, P.
15、G., l时空决定物质如何运动.Science Fact事实 or Fiction小说?l Do the theories of relativity prohibit 禁止interstellar星 际 travel旅行?we can not travel faster than the speed of lightbut what if we made the distance to our destination shorter?lNone of these ideas is prohibited by our current understanding of physics.lMost
16、 scientists are pessimistic悲观的 about the possibilities.lFor the moment, the Universe is safe for science fiction writers!We might tunnel through hyperspace(超空间) in a wormhole(虫洞).A wormhole connects two distant points in the Universe. Or perhaps we could warp(弯曲) spacetime so that two locations of our choosin
