南昌中影今日影讯宇宙大爆炸 时间简史:C8-Yin語

宇宙大爆炸 时间简史:C8-Yin語
作者开始结合前面几章提到的广义相对论,不确定性原理和量子力学以及黑洞的力学结构、奇点研究等,开始解答一直以来无数前辈尝试解答,摸索的终极问题之一——宇宙的起点在哪里?

1
现在几乎大家都知道,宇宙是有限的,宇宙的起源是138亿年前的那一次大爆炸;在西方的传统观念中,宇宙也是有限的李馨雨,来自于上帝的创始之手于敏家 。霍金提到了80年代他去梵蒂冈参加由耶稣会组织的宇宙学会议的场景:
At the end of the conference the participants were granted an audience with the Pope. He told us that it was all right to study the evolution of the universe after the big bang医道天下, but we should not inquire into the big bang itself because that was the moment of Creation and therefore the work of God.
教皇说道:大爆炸之后的宇宙演化是可以研究的,但是科学家们不要去探寻大爆炸本身——因为创世的那一刻,是上帝他老人家的神迹。
霍金又接着说道:
I was glad then that he did not know the subject of the talk I had just given at the conference – the possibility that space-time was finite but had no boundary, which means that it had no beginning, no moment of Creation.
空间-时间是有限但是无界的,也就是说没有开端,没有创世的时刻。
2
At the big bang itself the universe is thought to have had zero size, and so to have been infinitely hot.
大爆炸之初,宇宙的提及被认为是零黄勇杀人案 ,所以它本身是无限热的。(这个根据热力学定律应该很好解释)。宇宙的诞生可以说是一瞬间的事情,快到无法以秒计算阿茹茉妮,所以在讨论宇宙诞生的这个话题的时候,就会引入到一个新的时间尺度——普朗克时间(Planck Time)(光在真空中传播一个普朗克长度所需要的时间蔡高厅 ,它的数值大约是5× 10?44秒)。
在大爆炸后的一秒,宇宙温度降低到约为100亿度龙阳逸史,这大约是太阳中心温度的1千倍,亦即氢弹爆炸达到的温度。这个时候的宇宙是什么让的呢艾比盖尔 ?
At this time the universe would have contained mostly photons, electrons, and neutrinos (extremely light particles that are affected only by the weak force and gravity) and their antiparticles, together with some protons and neutrons. As the universe continued to expand and the temperature to drop, the rate at which electron/antielectron pairs were being produced in collisions would have fallen below the rate at which they were being destroyed by annihilation. So most of the electrons and antielectrons would have annihilated with each other to produce more photons, leaving only a few electrons left over. The neutrinos and antineutrinos, however, would not have annihilated with each other, because these particles interact with themselves and with other particles only very weakly. So they should still be around today.
此刻宇宙主要包含光子、电子和中微子(极轻的粒子,它只受弱力和引力的作用)和它们的反粒子,还有一些质子和中子。随着宇宙的继续膨胀,温度继续降低,电子/反电子对在碰撞中的产生率就落到它们湮灭率之下。这样只剩下很少的电子,而大部分电子和反电子相互湮灭夏桥街,产生出更多的光子。然而,中微子和反中微子并没有互相湮灭掉那溪那山 ,因为这些粒子和它们自己以及其他粒子的作用非常微弱,所以直到今天它们应该仍然存在——这就是宇宙微波背景(Cosmic Microwave Background),大约也就是5K—10K重返末日,大概接近于绝对零度,1964年有美国射电天文学大阿诺彭齐亚斯和罗伯特威尔逊偶然发现,并在1978年获得诺贝尔奖冷若萌 。
在大爆炸后的大约100秒,温度降到了10亿度,也即最热的恒星内部的温度。这时的宇宙是这样的:
At this temperature protons and neutrons would no longer have sufficient energy to escape the attraction of the strong nuclear force, and would have started to combine together to produce the nuclei of atoms of deuterium (heavy hydrogen)西岛俊秀, which contain one proton and one neutron. The deuterium nuclei would then have combined with more protons and neutrons to make helium nuclei, which contain two protons and two neutrons阿立未来 , and also small amounts of a couple of heavier elements韶华江山赋, lithium and beryllium.
在此温度下南昌中影今日影讯 ,质子和中子不再有足够的能量逃脱强核力的吸引,所以开始结合产生氘(重氢)的原子核。氘核包含一个质子和一个中子。然后楚奇楚童 ,氘核和更多的质子中子相结合形成氦核,它包含二个质子和二个中子,还产生了少量的两种更重的元素锂和铍。赵c (铍元素作为宇宙早期发展的遗迹,只在地外空间中有发现,地球上没有稳定态的铍元素)
大爆炸之后的几个小时,产生氦元素和其他元素的反映结束了,而后的百万的年,宇宙一直在持续膨胀。
直到温度下降到几千度时碓氷拓海 ,电子和核子没有能量在去抵抗它们间的互相吸引力,结合形成了原子。宇宙作为整体,继续膨胀变冷,但在一个略比平均更密集的区域,膨胀就会由于额外的引力吸引而慢下来。在一些区域膨胀会最终停止并开始坍缩。当它们坍缩时,在这些区域外的物体的引力拉力使它们开始很慢地旋转;当坍缩的区域变得更小,它会自转得更快——正如在冰上自转的滑冰者大宋权相 ,缩回手臂时会自转得更快;最终,当这些区域变得足够小,自转的速度就足以平衡引力的吸引,碟状的旋转星系就以这种方式诞生了陆云生 。
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