http://www.economist.com/node/17626874
In contradiction to most cosmologists’ opinions, two scientists have found evidence that the universe may have existed for ever.
Going Round in Circles
WHAT happened before the beginning of time is—by definition, it might be thought—metaphysics. At least one physicist, though, thinks there is nothing meta about the question at all. Roger Penrose, of Oxford University, believes that the Big Bang in which the visible universe began was not actually the beginning of everything. It was merely the latest example of a series of such bangs that renew reality when it is getting tired out. More importantly, he thinks that the pre-Big Bang past has left an imprint on the present that can be detected and analysed, and that he and a colleague in Armenia have found it.
The imprint in question is in the cosmic microwave background (CMB). This is a bath of radiation that fills the whole universe. It was frozen in its present form some 300,000 years after the Big Bang, and thus carries information about what the early universe was like. The CMB is almost, but not quite, uniform, and the known irregularities in it are thought to mark the seeds from which galaxies—and therefore stars and planets—grew.
Dr Penrose, though, predicts another form of irregularity—great circles in the sky where the microwave background is slightly more uniform than it should be. These, if they exist, would be fossil traces of black holes from the pre-Big Bang version of reality. And in a paper just published in arXiv.org, an online database, he claims they do indeed exist.
Once upon a time
The Penrose version of cosmology stands in sharp distinction to received wisdom. This is that the universe popped out of nowhere about 13.7 billion years ago in a quantum fluctuation similar to the sort that constantly create short-lived virtual particles in so-called empty space. Before this particular fluctuation could disappear again, though, it underwent a process called inflation that both stabilised it and made it 1078 times bigger than it had previously been in a period of 10-32 seconds. Since then, it has expanded at a more sedate rate and will continue to do so—literally for ever.
Dr Penrose, however, sees inflation as a kludge. The main reason it was dreamed up (by Alan Guth, a cosmologist at the Massachusetts Institute of Technology) was to explain the extraordinary uniformity of the universe. A period of rapid inflation right at the beginning would impose such uniformity by stretching any initial irregularities so thin that they would become invisible.
As kludges go, inflation has been successful. Those of its predictions that have been tested have all been found true. But that does not mean it is right. Dr Penrose’s explanation of the uniformity is that, rather than having been created at the beginning of the universe, it is left over from the tail end of reality’s previous incarnation.
Dr Penrose’s version of events is that the universe did not come into existence at the Big Bang but instead passes through a continuous cycle of aeons. Each aeon starts off with the universe being of zero size and high uniformity. At first the universe becomes less uniform as it evolves and objects form within it. Once enough time has passed, however, all of the matter around will end up being sucked into black holes. As Stephen Hawking has demonstrated, black holes eventually evaporate in a burst of radiation. That process increases uniformity, eventually to the level the universe began with.
Thus far, Dr Penrose’s version of cosmology more or less matches the standard version. At this point, though, he introduces quite a large kludge of his own. This is the idea that when the universe becomes very old and rarefied, the particles within it lose their mass.
That thought is not entirely bonkers. The consensus among physicists is that particles began massless and got their mass subsequently from something known as the Higgs field—the search for which was one reason for building the Large Hadron Collider, a huge and powerful particle accelerator located near Geneva. Mass, then, is not thought an invariable property of matter. So Dr Penrose found himself speculating one day about how a universe in which all particles had lost their mass through some as-yet-undefined process might look. One peculiarity of massless particles is that they have to travel at the speed of light. That (as Einstein showed) means that from the particle’s point of view time stands still and space contracts to nothingness. If all particles in the universe were massless, then, the universe would look to them to be infinitely small. And an infinitely small universe is one that would undergo a Big Bang.
Uncommon sense
It is well known that fundamental physics is full of ideas that defy what humans are pleased to call common sense. Even by those standards, however, Dr Penrose’s ideas are regarded as a little eccentric by his fellow cosmologists. But they do have one virtue that gives them scientific credibility: they make a prediction. Collisions between black holes produce spherical ripples in the fabric of spacetime, in the form of gravitational waves. In the Penrose model of reality these ripples are not abolished by a new Big Bang. Images of black-hole collisions that happened before the new Bang may thus imprint themselves as concentric circular marks in the emerging cosmic microwave background.
The actual search for such cosmic circles has been carried out by Vahe Gurzadyan of the Yerevan Physics Institute in Armenia. Dr Gurzadyan analysed seven years’ worth of data from WMAP, an American satellite whose sole purpose is to measure the CMB, and also looked at data from another CMB observatory, the BOOMERanG balloon experiment in Antarctica. His verdict, arrived at after he scoured over 10,000 points on the microwave maps, is that Dr Penrose’s concentric circles are real. He says he has found a dozen sets of them—one of which is illustrated. (The visible rings in the picture have been drawn on subsequently to show where computer analysis has found circle-defining uniformity.)
This is, of course, but a single result—and supporters of inflation do not propose to give up without a fight. Amir Hajian, a physicist at Princeton, for example, says he is concerned about distortions in the WMAP data caused by the satellite spending more time mapping some parts of the sky than others. Then there is the little matter of how the masslessness comes about.
Dr Guth, meanwhile, claims that a handful of papers are published every year pointing to inconsistencies between the microwave background data and inflation, and that none has withstood the test of time. Moreover, even if the circles do hold up, they may have a cause different from the one proposed by Dr Penrose. Nevertheless, when a strange theory makes a strange prediction and that prediction proves correct, it behoves science to investigate carefully. For if what Dr Penrose and Dr Gurzadyan think they have found is true, then much of what people thought they knew about the universe is false.
- Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/07/2010
又是这个 Penrose? 他说要用量子力学才能解释自我意识的现象,从来没让人信服过。
大爆炸之前是什么样,就象小时候问宇宙有没有边,如果有,边外面是什么一样,simply fasinating. - posted on 12/08/2010
gz wrote:
又是这个 Penrose? 他说要用量子力学才能解释自我意识的现象,从来没让人信服过。
大爆炸之前是什么样,就象小时候问宇宙有没有边,如果有,边外面是什么一样,simply fasinating.
什么“又是这个”,搞得我去咕咕了一下他,好像很有名也,看起来和霍金一样有名,但是没霍金流行。天知道霍金怎么流行了呢。
这个理论我还蛮喜欢的,虽然我不懂物理。"......believes that the Big Bang in which the visible universe began was not actually the beginning of everything. It was merely the latest example of a series of such bangs that renew reality when it is getting tired out......he thinks that the pre-Big Bang past has left an imprint on the present that can be detected and analysed".
特别是,“That (as Einstein showed) means that from the particle’s point of view time stands still and space contracts to nothingness. If all particles in the universe were massless, then, the universe would look to them to be infinitely small. And an infinitely small universe is one that would undergo a Big Bang. ”
这好像爱情啊。原来是有永恒的的爱情的,particle的爱情。前世的记忆就是Big Bang前留下的imprint. 两个粒子的爱情。 - posted on 12/08/2010
传统理论认为中国掘起之初的快速通胀不久即会导致收入分布的均匀化,使大家对改革初始的贫富不均视而不见。。。
膨弱视博士对均匀性的解释是均匀性在发达社会的开初是不存在的,它要到接近尾声时才出现...膨弱视博士认为社会是在不断循环中发展完善的。在每一循环开始时,每个人的财富为零,所以大家是平等的,财富分配是均匀的。...随着时间的发展,所有财富会被吸入一个大黑洞中,最终大黑洞也会灰飞烟灭,走向均匀,复归原位。
小麦 wrote:
http://www.economist.com/node/17626874 ...A period of rapid inflation right at the beginning would impose such uniformity by stretching any initial irregularities so thin that they would become invisible.
....Dr Penrose’s explanation of the uniformity is that, rather than having been created at the beginning of the universe, it is left over from the tail end of reality’s previous incarnation.
Dr Penrose’s version of events is that the universe ...passes through a continuous cycle of aeons. Each aeon starts off with the universe being of zero size and high uniformity. ...Once enough time has passed, however, all of the matter around will end up being sucked into black holes... As Stephen Hawking has demonstrated, black holes eventually evaporate in a burst of radiation. That process increases uniformity, eventually to the level the universe began with.
- Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/08/2010
小麦 wrote:
这好像爱情啊。原来是有永恒的的爱情的,particle的爱情。前世的记忆就是Big Bang前留下的imprint. 两个粒子的爱情。
现代物理的理论远远超出人的常识之外,什么高维空间,多重平行宇宙什么的。所以 romanticizing these theories is probably the second best thing we ordinary people can do. 什么前世的爱情,百年修得同船渡,千年修得共枕眠之类,现在都能解释了。多亏这位老潘螺蛳! - posted on 12/08/2010
gz wrote:
现代物理的理论远远超出人的常识之外,什么高维空间,多重平行宇宙什么的。所以 romanticizing these theories is probably the second best thing we ordinary people can do. 什么前世的爱情,百年修得同船渡,千年修得共枕眠之类,现在都能解释了。多亏这位老潘螺蛳!
虽然不是常识,但是可以是common sense,高维空间、平行宇宙我觉着都可以感知啊。不知为什么,我倒觉着Penrose的宇宙循环是common sense呢。
这个百年、千年我曾经想的是:路人要修百年(还是十世啊?不管吧,就当一世是十年吧反正时间也不是固定的),一夜情要修千年,那爱人、夫妻还不都早修成妖精了,但是修成妖精也没用,不保证长久。现在看来是:不要管修成什么,一世一世的修就是了。
另外,这个Penrose,啊啊,上回我看伊斯兰建筑图案里的对称性是就有他啊,准晶体的、五倍旋转对称的彭罗斯拼图 Penrose tiling。 - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/08/2010
以前民风淳朴,其实“共振眠”应该就是夫妻的意思吧。
好几年前附近一个高中请我们去评判学生的 science project, 其中一个学生做的就是有关潘螺蛳的 tiling.这个老潘涉猎真够广的,从铺瓦到意识到大爆炸都来得。 - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/08/2010
小麦也有盲点?那潘螺丝也是制度啦。全世界最起劲搞脑子的,他名列前茅。 ;)
浮生的common sense,不是一般人的,应该算是uncommon sense。 ;) - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/08/2010
touche wrote:
小麦也有盲点?
图老爷你这是拿我凑趣呢。没盲点我还是人吗?除了有盲点,绝大部分事情上我都是无知的。
另外,风子,你的触类旁通太牛了。还有关中,彭罗斯的铺瓦意识大爆炸你有空给科普一下吧。
最后,浮生,你out了。国内上半年流行的段子是,“十年修得同船渡。百年修得共枕眠。千年修得同性恋。万年修得性冷淡。”
- posted on 12/08/2010
小麦自己慢慢科普吧:
http://en.wikipedia.org/wiki/Penrose_tiling
他说意识的基础是量子理论,还要扯上歌德尔的不完全性理论,我无法接受,所以书买了很久也没看进去。也许小麦可以:
http://en.wikipedia.org/wiki/The_Emperor's_New_Mind
http://en.wikipedia.org/wiki/Shadows_of_the_Mind
还得谢谢小麦的科普,才知道他还有这个关于大爆炸之前的理论。此前谈论大爆炸以前的事是要被人笑话的。他反正已经 knighted, 可以随便瞎忽悠了。
http://www.bbc.co.uk/news/science-environment-11837869
最后,浮生,你out了。国内上半年流行的段子是,“十年修得同船渡。百年修得共枕眠。千年修得同性恋。万年修得性冷淡。”
LOL
不怪浮生,是我 out 了。:-) - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/09/2010
gz wrote:
小麦自己慢慢科普吧:
回头找浮生给我科普去。
此前谈论大爆炸以前的事是要被人笑话的。
天,别说科学家,就算平常人,活过30岁,如果连点不怕被人笑话的勇气都没有,基本算白活了。
- posted on 12/10/2010
正在学习, 有点半懂不懂的感觉,还是科普一下, 我很有兴趣了解, 但是又不懂, 浮生的常识不算数。 对我可不是常识。
我的macbook坏了,苹果的天才吧的天才说是
startingboard 坏了, 要900 刀修,有人知道吗?买个新的?
谢谢joey, 终于可用iiphone写了。
浮生 wrote:
gz wrote:虽然不是常识,但是可以是common sense,高维空间、平行宇宙我觉着都可以感知啊。不知为什么,我倒觉着Penrose的宇宙循环是common sense呢。
现代物理的理论远远超出人的常识之外,什么高维空间,多重平行宇宙什么的。所以 romanticizing these theories is probably the second best thing we ordinary people can do. 什么前世的爱情,百年修得同船渡,千年修得共枕眠之类,现在都能解释了。多亏这位老潘螺蛳!
这个百年、千年我曾经想的是:路人要修百年(还是十世啊?不管吧,就当一世是十年吧反正时间也不是固定的),一夜情要修千年,那爱人、夫妻还不都早修成妖精了,但是修成妖精也没用,不保证长久。现在看来是:不要管修成什么,一世一世的修就是了。
另外,这个Penrose,啊啊,上回我看伊斯兰建筑图案里的对称性是就有他啊,准晶体的、五倍旋转对称的彭罗斯拼图 Penrose tiling。 - posted on 12/10/2010
草叶,花900刀不如买新的了,是Pro还是不是,若是前者还要心疼下,后者的话全新的也就一千吧。估计你的是出了一年的保修,但没买三年的?
那个常识,嘻嘻,我没有说是知识上的常识哦,sense是用mind's eye来看的,具体的我当然是不懂的。我说的就是通俗宇宙观拉,有始有终的宇宙我觉着才是难理解的,begging the question。高维空间就好像一维看不到二维,二维看不到三维,但都知道彼此的存在,那我们看不到更高维但同样可以知道它的存在。就象前次讨论人的眼睛可以感知的颜色一样,我们虽然看不到鸟眼的世界,但我们知道它是存在的,不仅如此,还可以有确切的表述。平行宇宙我觉着也是类似的意思,虽然那个表述我们外行可能就更难理解了。
另外,小麦,我从来没in过,何来out? - posted on 12/10/2010
是pro, 早过了保修期, 新的是两倍的价,我在想买个ipad, 然后一个desk top, 好不好? 我的计算机就是要有存足够的照片和video的能力就行了。
谢科普,有没有谈big bang的老线,让我复习一下, 劳谁挖一下。
你说有始有终的宇宙才是难理解的,推而广之, 那你是如何看生物种的始终呢?这理论对 DNA的起源有何影响?
浮生 wrote:,有始有终的宇宙我觉着才是难理解的,begging the question。高维空间就好像一维看不到二维,二维看不到三维,但都知道彼此的存在,那我们看不到更高维但同样可以知道它的存在。。
草叶,花900刀不如买新的了,是Pro还是不是,若是前者还要心疼下,后者的话全新的也就一千吧。估计你的是出了一年的保修,但没买三年的?
- Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/10/2010
浮生 wrote:
。。。我说的就是通俗宇宙观拉,有始有终的宇宙我觉着才是难理解的
那开始以前是什么样,终止以后呢?
有人说空间是有限但无边,就象三维空间的二维球面。莫非时间也可以这样?日子过着过着就回到从前了。浮生一世一世的修,就修回去了。
浮生玩好吃好啊! - posted on 12/10/2010
浮生 wrote:
我说的就是通俗宇宙观拉,有始有终的宇宙我觉着才是难理解的,begging the question。
嗯,我也觉得是这样。
高维空间就好像一维看不到二维,二维看不到三维,但都知道彼此的存在,那我们看不到更高维但同样可以知道它的存在。就象前次讨论人的眼睛可以感知的颜色一样,我们虽然看不到鸟眼的世界,但我们知道它是存在的,不仅如此,还可以有确切的表述。
mutually不一定。鸟虽然"看"的颜色比我们多,但估计不"知道"我们眼中的世界是什么样。一维不能“看到”二维,二维不能“看到”三维,也未必能“知道”三维的是什么。三维能“看到”二维,也未必能“知道”二维是什么样。“看”是低维的,“知”是高维的。我什么都不懂,胡扯一通哈。
另外,小麦,我从来没in过,何来out?
我不“知道”你没in过啊(你和颓废仔不是在高维成仙了嘛),我的解读只能是你out了。这就是一维二维眼中的来自三维世界的现象。 - posted on 12/10/2010
gz wrote:
那开始以前是什么样,终止以后呢?
你怎么问我啊,我是相信无始无终的。
有人说空间是有限但无边,就象三维空间的二维球面。莫非时间也可以这样?日子过着过着就回到从前了。浮生一世一世的修,就修回去了。
恩,我也看到过这个说法,如果基于大爆炸的那make sense。
根据开篇的文章,我的理解,时间和空间是一回事儿吧,是不是啊?
没看我都out了么,哪还敢随便修下去啊,适可而止,适可而止。
小麦,那个“看”和“知”我用词比较混乱而且谁看谁知也不分,你就拟人化一下得了。说这些还不都是胡扯啊,不懂正好胡扯。
草叶,我觉着对DNA或生命起源不应该有影响啊。如果生命能从primordial soup里产生,那宇宙循环还是不循环都没有关系吧,因为生命是完全被包含在宇宙之中的啊,完全不同的scale。至于生物种的始终,如果把物种看作宇宙,DNA或是别的基本单位看作粒子,那在生命的路程中我觉着是可以说循环的,从这个意义上生命是永恒的,or almost。
顺便,别问我ipad哈,我不是粉。那你难道不需要一个电脑可以拎着走的么?ipad不能拿来干正事儿吧?如果不需要,那当然是desktop的性价比高了。 - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/10/2010
浮生 wrote:
gz wrote:你怎么问我啊,我是相信无始无终的。
那开始以前是什么样,终止以后呢?
是够 out 的。线性宇宙早就没人信了。 - posted on 12/10/2010
浮生 wrote:
那个常识,嘻嘻,我没有说是知识上的常识哦,sense是用mind's eye来看的,具体的我当然是不懂的。我说的就是通俗宇宙观拉,有始有终的宇宙我觉着才是难理解的,begging the question。高维空间就好像一维看不到二维,二维看不到三维,但都知道彼此的存在,那我们看不到更高维但同样可以知道它的存在。就象前次讨论人的眼睛可以感知的颜色一样,我们虽然看不到鸟眼的世界,但我们知道它是存在的,不仅如此,还可以有确切的表述。平行宇宙我觉着也是类似的意思,虽然那个表述我们外行可能就更难理解了。
比如人死了变成鬼,就比较好理解,死了什么都没了,才难理解。 - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/13/2010
行人 wrote:
比如人死了变成鬼,就比较好理解,死了什么都没了,才难理解。
好像这里前一阵谈“死亡”才在说基因说不是什么都没了.
你们什么时候开个死亡专线,有助于我理解死亡. :) - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/13/2010
你们什么时候开个死亡专线,有助于我理解死亡. :)
记得有过死亡线了,咖啡几个小资 MM 曾经热议过死时倒在谁怀里的问题。:-) - Re: (zt) Before the Big Bang: Going Round in Circlesposted on 12/13/2010
是,我还记得小资gz 慷慨激昂地表示要死在大自然的怀里。:)
gz wrote:
你们什么时候开个死亡专线,有助于我理解死亡. :)记得有过死亡线了,咖啡几个小资 MM 曾经热议过死时倒在谁怀里的问题。:-) - posted on 12/13/2010
浮生的常识,也即是自然。而科学发展势必要人为,无论是牛顿体系林奈体系还是
圣经大爆炸体系都是人为,但这人为相当必须,也给人认识相当的助益。
就象秋天漫天坠叶,有人只拿一片叶,仔细格物良久,写了一首诗。
记得以前阿姗得道了那段High的时候,我让她顺便理想大爆炸,她说要爆的,还拿
圣经创世纪作比,四千多年前人的眼力,如今人与仪器的观测力。我当时很受益,
以前也觉得大爆炸生硬。之前之后,平行宇宙,怕都脱不开大爆炸模型,也是人胎
卵受孕分娩等原记忆。
我觉得Penrose的东方思维(古典或佛教轮回),无始无终,三千大千世界,虽然自
然完备,但也等于什么都没说。因为,就象居维叶开拓地球历史,从六千年到若干
百万年,虽突破圣经,还是有个46亿年,及后还有140亿年的宇宙。这平行宇宙最
多一次革命,有精力的天主基督精神势必会有另一场新起始,
在更大的基础上统一!毕竟,统一力大于平行分散力,无界轮回的时间不聚焦。
浮生 wrote:
gz wrote:虽然不是常识,但是可以是common sense,高维空间、平行宇宙我觉着都可以感知啊。不知为什么,我倒觉着Penrose的宇宙循环是common sense呢。
现代物理的理论远远超出人的常识之外,什么高维空间,多重平行宇宙什么的。所以 romanticizing these theories is probably the second best thing we ordinary people can do. 什么前世的爱情,百年修得同船渡,千年修得共枕眠之类,现在都能解释了。多亏这位老潘螺蛳!
- posted on 12/15/2010
xw好像喜欢非此即彼,不是一次了哦。这宇宙循环论和大爆炸哪里有矛盾啊?
人为,人当然是喜欢唯一的,宇宙只爆炸一次,生命只出现一次,人只出现一次。。。不过循环、平行也不是说形式上的完全相同吧,只是说时间、空间上的过程。但是说唯一也有唯一的意义,就是在时空的某个焦点上的唯一性。比如人类一直要找外星人,起初的问题是有没有外星人,这回答应当是肯定的(我觉着哈),真正的问题应当是,是否有“外星人”和我们处在同一个时空(时空距离上足够近),寻找的目的非只为了证明存在,到底还是为了交流,但这第二个问题的答案更大的可能是没有(还是我觉着哈),若如此这便是我们人类的唯一性。
行人,人死了当然不是什么都没有了,变成什么倒不是重要的。以前人爱说皮囊,其实就是的。我说的也还是物质哈。 - posted on 12/15/2010
浮生 wrote:
xw好像喜欢非此即彼,不是一次了哦。这宇宙循环论和大爆炸哪里有矛盾啊?
大爆炸好像也没说炸之前什么都没有,只是说爆炸开始时宇宙坍塌成一个奇点,之前不论有什么,一切结构一切信息都消失了,咱们永远也不可能知道大爆炸之前有过什么。宇宙循环论倒是不矛盾,但却无法证实。
“难道妈妈没有告诉你,不知道的事不要瞎说?”
行人,人死了当然不是什么都没有了,变成什么倒不是重要的。以前人爱说皮囊,其实就是的。我说的也还是物质哈。
哦,人死了还有个死人,把这茬忘了。
- posted on 12/17/2010
TLS这期哲学家给霍金和彭罗斯的书评。
(不晓得为什么,所有纸板和电子版的同一篇文章都喜欢用不同的标题。这篇纸版的标题是Infinite Variety, 电子版变成了God's Equations?。
http://entertainment.timesonline.co.uk/tol/arts_and_entertainment/the_tls/article7169877.ece
God's equations?
Is the universe a ‘fluctuation, like a bubble in boiling water’, or part of a succession of Big Bangs – and where do competing theories leave a Creator?
John Leslie
Why is there a universe, not a blank? The Grand Design and Cycles of Time suggest very different answers. Stephen Hawking and Leonard Mlodinow make The Grand Design reader-friendly. Its physics and cosmology are enlivened by myth (“In the Mayan legend the Maker, unhappy because there was no one to praise him, decided to create humans”). You’ll find colourful artwork, jokes, a quick history of science, no mathematics. And the book can seem astonishingly open-minded. Even Archbishop Ussher’s view that things began in 4004 BC appears to get considerable respect. Suppose that Ussher’s modern disciples taught that in 4004 BC God created the universe exactly as if it had existed for billions of years, inclusive of fossils in the rocks: Hawking–Mlodinow’s “model-dependent realism” wouldn’t call their teaching mistaken, or its imagined facts “less real” than those you presumably believe in.
“Philosophy”, the book declares, “is dead. Philosophy has not kept up with modern developments in science.” The authors then make bold philosophical claims. For example they aren’t attracted by the idea, perhaps it has never occurred to them, that even chess-playing computers “make choices” in a sense. So they theorize that “though we feel that we can choose what we do”, we are in fact “governed by the laws of physics and chemistry”, which at once proves we can’t. Presumably, they hope that after weighing the alternatives we will select their theory without actually choosing it.
Again, Hawking and Mlodinow treat quantum theory controversially. What could terminate “quantum superpositions” in which seemingly contradictory situations are combined? For instance a cat – anaesthetized, observing nothing, its fate linked to an atom liable to decay radioactively – with the seemingly incompatible properties of being alive and being dead. Or an electron’s passage through a left slit, as a particle, and simultaneously through a right slit, once again as a particle, and simultaneously also through both slits, as a wave. Only observations could have the power to terminate such paradoxical states, on the book’s world-view: “the unobserved past is indefinite”. That’s philosophically bold. Cannot photographic film record how superpositions have “collapsed” into unparadoxical realities long before the film is developed and observed? And how about our efforts to build quantum computers in which superpositions perform complex calculations? Aren’t we seemingly thwarted by how the superpositions keep collapsing before we look at them?
What, though, if we accepted a many-branched universe? It’s what Hawking and Mlodinow often seem to want (but reader-friendliness combines with “model-dependent realism” to mean their readers cannot be sure). All branches are equally real, for despite appearances superpositions never collapse. They instead grow to include whomever observes them; any observer develops seemingly incompatible properties. In a complex sense, the observer splits or branches. Well, scientists in the “quantum cosmology” community mostly accept this. However, they would typically reject the book’s idea that all branching depends on observations. Suppose your double, your “other half” with seemingly incompatible properties, inhabits a universe-branch where a cat is alive. In your branch a double of the cat is dead. Looking to see which branch you inhabited needn’t, most of them would say, be what killed that cat.
The book’s ideas about creating the past render matters worse. “Observations you make on a system in the present affect its past.” This is proved, the authors say, by “delayed choice experiments” where any question to be asked experimentally is decided at a late moment. Yet couldn’t you instead claim that past events merely looked as if they’d taken particular forms, or else that they took them, but only in a universe-branch into which the experimental decision helped to place you? Either way, nothing ever reacts to a choice which hasn’t yet been made. (In a double-slit experiment, suppose any question is delayed until an electron fired at the slits has passed beyond them. At that late stage, choosing to ask which slit the electron went through may get the answer, “the left one, apparently”. Choosing not to ask it makes it seem that the electron traversed both slits as a wave. But why say the electron really did one thing rather than another, or did it in a way commanded by the choice that came later?)
Then there are the claims about why our universe exists. There’s no need, we’re told, for a deity “to light the blue touch paper and set the universe going”. At our universe’s beginning, quantum chaos replaced time by a fourth dimension of space. Inquiring what came beforehand is like asking how much of Earth’s surface lies south of the South Pole. Now, this wouldn’t satisfy St Augustine. For Augustine just as for Hawking and Mlodinow, time began only once the world arrived; however, God lit the touch paper. But, says the book, the right explanation is that our universe is a fluctuation like a bubble in boiling water, yet costing nothing in energy. As is widely accepted, gravitational energy is negative energy. It can exactly counterbalance all the positive energy of the universe’s atoms, light rays, and so forth: the Einsteinian mass-energy of their existence and movement. Total energy is therefore zero. Hence there is no need for a Creator. Immense numbers of bubble-universes simply fluctuate into being.
In each universe four-dimensional space soon becomes eleven-dimensional space-time if “M-theory” is right. Currently popular, M-theory is a Theory of Everything. But Hawking and Mlodinow appear confident that it does not dictate the strengths of forces such as electromagnetism, the masses of particles such as the neutron, or even what types of force and of particle exist. Instead it specifies that dimensions can become “compactified”, curled up too tightly to be visible. How many curl up, and with just what sort of curling, varies from universe to universe in an immense number of ways. The number could be 1 followed by 500 zeros.
In our universe four dimensions remain uncompactified: three of space, one of time. The actual manner in which the others have curled up produces the forces and particles we observe. The immense variety of the universes explains how the observed force strengths and particle masses manage to be fine-tuned to life’s stringent requirements. In almost all the universes, things aren’t “just right” in ways permitting life to evolve; but then, there’s nobody there to observe anything. Now as Hawking and Mlodinow comment, this wouldn’t please Cardinal Schönborn. Writing that the multiverse (many universes) hypothesis is something “invented to avoid . . . overwhelming evidence for purpose and design”, Schönborn wants a Fine-Tuner. Other churchmen let God create a multiverse if that’s God’s preferred way of ensuring that life will evolve somewhere or other. What’s intriguingly atheistic in The Grand Design isn’t its multiverse. Instead it’s a combination of two startling philosophical themes.
First: while denying that a Theory of Everything gives every universe the same “apparent” laws, the ones that result from just how dimensions have curled up, Hawking and Mlodinow suggest that the underlying laws, those of M-theory, are the sole ones that are logically possible. Second: they abandon Hawking’s earlier idea that no matter what our physical equations there’ll always be a need for something “to breathe fire into the equations, making a universe for them to govern”.
Can they possibly be correct? Could a universe “costing nothing in energy” escape the need for the fire? Imagine an equation specifying that the number of devils grows at fifty-six devils per second. If the equation applied to reality then there’d have to be a universe: one with lots of devils at least. Yet why should it apply to reality? Because the equation itself guaranteed there’d be devils for it to apply to? Or because the total energy was zero? Well, how could that explain the very existence of a universe?
It couldn’t make it more understandable logically, because every universe that wasn’t self-contradictory would be neither more nor less logically viable than an absolute blank. “Logically necessary” just means necessary for contradictions to be avoided. It’s logically necessary that any bachelor’s cousin has a cousin who is unmarried. Now, how could anything of the sort tell a universe to exist? Hawking and Mlodinow suggest “that abstract considerations of logic lead to a unique theory that predicts and describes a vast universe”. How could they justify that idea?
Their attempt runs as follows. (A) “Any set of laws that describes a continuous world such as our own will have a concept of energy, which is a conserved quantity, meaning it doesn’t change in time”. (B) “One requirement any law of nature must satisfy is that . . . the energy of an isolated body surrounded by empty space is positive”, for otherwise “there would be no reason that bodies could not appear anywhere and everywhere.” (C) “The positive energy of the matter can be balanced by the negative gravitational energy, and so . . . the universe can and will create itself from nothing.” (D) “M-theory is the most general supersymmetric theory of gravity . . . the only candidate for a complete theory of the universe.”
Let’s protest: (A) What’s self-contradictory in a wheel turning faster and faster without getting its increasing power from anywhere? And when Wolfgang Pauli dreamed up neutrinos to balance his energy equations, did the Law of Non-Contradiction create them? (B) Which logic says Nature must have “laws” instead of bodies appearing just anywhere? (C) “. . . and so can and will create itself”? What breathed fire into that? (D) Symmetry between matter particles and force-carrying particles, “supersymmetry”, allows infinities to cancel one another. Yet which logic demands such particles, let alone the quantum-theoretical details that threaten to create infinities?
However, the physics of The Grand Design could survive – and could make the book important – without quite so many philosophical claims. Quantum theory does seem to make our universe many-branched, the “jostling” of the branches helping explain the results of double-slit experiments. Conservation of mass-energy is so beautiful that even an omnipotent deity might like it. And the multiverse way of explaining the fine-tuning looks attractive.
Given very large deviations from the force strengths and particle masses we observe, heaven knows whether life would be possible. Our arguments would grope in the dark. But any of twenty or more tiny deviations would seem fatal. Some could be deviations by as little as one part in 1 followed by twenty or more zeros. Now, a force strength or a particle mass often needed tuning to within the same narrow limits for many different reasons at once. How could this be understood without a multiverse?
Consider electromagnetism. How is it that electromagnetism didn’t need tuning to one strength to stop quarks turning into leptons, making atoms impossible, to another very different strength for protons not to decay quickly, destroying their atoms, to yet another strength for there to be suns burning peacefully for billions of years, and so on and so forth? How did one and the same strength manage to satisfy ten or more potentially conflicting requirements? How is it that even a single possible combination of force strengths and particle masses is life-permitting? Solving the conundrum might require some sort of God to select Nature’s laws propitiously. (Perhaps not some inexplicably existing Creator; I’m notorious for picturing God as perhaps the Principle that abstract requirements of Value can, as Plato suggested, themselves act creatively; however, Plato’s suggestion might throw light on a Creator’s existence.) Still, if God worked with a Theory of Everything that had reasonably brief equations, ones that could be written on the back of an elephant, then bringing in God might not solve the conundrum. Not unless those equations described universes in a number of varieties as enormous as the 1 followed by 500 zeros that Hawking and Mlodinow mention. The difficulty then mightn’t arise in one or two universes.
In Cycles of Time, Roger Penrose pictures a cosmos that always has existed, “a succession of aeons, each appearing to be an entire expanding universe history”, a series of Cycles all much alike. He finds it comfortingly similar to the steady-state cosmos fashionable in the early 1950s, where atoms popped into existence at a very slow rate so that the cosmic expansion wouldn’t dilute everything. The arrival of the new atoms could be a fundamental law of nature. Fred Hoyle saw this as far better than what he contemptuously christened “the Big Bang” where an entire universe arrived all at once. Later, the Big Bang became widely accepted. Yet until he invented his Cycles, in 2005, Penrose regretted the death of Hoyle’s “philosophically attractive” universe that “requires no origin in time”.
No origin in time. Would that remove the need for a Creator? Penrose doesn’t actually say so. Still, philosophers from Epicurus to Bertrand Russell have said it. In Hume’s Dialogues Concerning Natural Religion, Philo sees no mystery in why a universe exists. Its existence at each moment is explained by its existence at the preceding moment.
Penrose is intrigued by the Law of Increasing Entropy, that the universe develops ever more disorder. The flow towards disorder gives rise to eddies of increased local orderliness such as plants and humans. Where did the initial orderliness (“low entropy”) come from? To some folk, a universe’s initial state could never be miraculous: miracles are breakdowns in laws operating up to date, and there’d not be any earlier dates. Penrose scorns this easy way out. Imagine, he says, that a universe sprang into existence looking much as ours does now. Imagine it developing backwards in time. When its Big Bang arrived, you’d seemingly expect horrendous disorder.
In The Emperor’s New Mind (1999), Penrose had a drawing (which he drew himself, then revised for The Road to Reality) showing a Creator placing a pin into a Big Bang initial state chosen from all the states available. To avoid a state of horrendous disorder, placing the pin could need accuracy to one part in 10 to the power of 10, in turn raised to the power of 123 (though Penrose would now change 123 to 124). If you wrote 1,000 and then added a zero for every single atom in the known universe you would only be beginning to express such a colossal number. While not actually saying he wants to push God nearer to unemployment, Penrose dislikes such supergigantic numbers. Yet he hates the currently popular “inflationary” attempt to get rid of them.
“Inflation” theory declares that at early times the Bang, after starting to slow, suddenly underwent extremely brief acceleration which expanded the universe enormously. Its size could have become greater by 10 to the power of 100 (which is 1 followed by 100 zeros). Earlier disorderliness was smoothed away, it is alleged, much as a balloon’s wrinkles disappear when it is inflated. But to Penrose the disorderliness would have been far too large for such smoothing away, were it not for a new principle.
The principle concerns the Big Bang’s “geometry”. The “geometry” of Earth’s surface is what makes large triangles drawn on it have angles that total far more than 180 degrees. Penrose’s proposed new constraint on the Bang’s geometry would, he judges, force smoothness in a way more philosophically acceptable than God placing a pin. Given the right geometry, what came out of the Bang would be almost evenly distributed.
But mightn’t that be rather overdoing things? When gas molecules are distributed evenly through a sealed cylinder, the gas has maximum entropy. There can’t then be a flow towards greater entropy, like the current whose eddies include plants and humans. Yes; but the gas of the early universe gravitated into clumps which became stars. One sort of entropy, Penrose explains, increases when gas distributes itself evenly, but gravitational entropy increases through clumping.
The new book then tells of the cosmic Cycles. Only experts could follow the details, some banished to appendices. But the story is exciting. The gist is this. The universe continues expanding and cooling, for what you might think would be eternity. How, you ask, could eternity ever end in a new Cycle, a new Bang? Well, even infinite time doesn’t look infinite to photons, “particles of light” without mass (more technically, without “rest-mass”). To a photon, traversing an infinite distance seems to take no time at all. Particles possessing mass are tiny “clocks”. The photon isn’t. It doesn’t “tick”. And, immense ages after all black holes have evaporated entirely through the process discovered by Hawking, the universe may contain nothing that could act as a clock. Particles possessing mass may one and all have become massless very, very gradually. Well, in Einstein’s world clocks are crucial to measuring distances. If eventually there were no clocks, just any distance could readily be traversed. Not only could the universe stop getting older and older; it could actually lose its vastness. This would allow things to carry over smoothly into a new Bang.
There’s another key component of the story. In each Cycle gigantic black holes are formed. Black holes have very disorderly interiors. When gigantic black holes evaporate, mustn’t they scatter huge disorder into the surrounding universe, making it far too chaotic to generate an orderly new Bang? Penrose answers that all information about a black hole’s interior, all trace of the disorder that reigns there, is lost during its evaporation.
The story certainly presents an extraordinary new view of the universe, but it could be proved right, Penrose hopes, by what is currently interpreted as Inflation’s imprint on the sky. Delicate tests could support his competing interpretation. Again, the violence when black holes merged during the previous Cycle could leave patterns for us to find.
Stories of an eternally oscillating cosmos (Big Bang, Big Squeeze, Big Bang) will probably attract far more scientists. So will the story of a cosmos in perpetual chaotic inflation. Because gravitational energy is negative, and hence can counterbalance other energy, the inflation can continue for ever. Inside its chaos, Big Bang universes are bubbles of comparative orderliness. Yet Roger Penrose might have the best story.
Stephen Hawking and Leonard Mlodinow
THE GRAND DESIGN
New answers to the ultimate questions of life
200pp. Bantam. £18.99.
978 0 593 05829 9
Roger Penrose
CYCLES OF TIME
An extraordinary new view of the universe
320pp. Bodley Head. £25.
978 0 224 08036 1
John Leslie is Professor Emeritus of Philosophy at the University of Guelph, Adjunct Professor of Philosophy at the University of Victoria, and a Fellow of the Royal Society of Canada. His Infinite Minds: A philosophical cosmology, was published in 2001, while his “The Risk that Humans Will Soon Be Extinct” appeared in the October issue of Philosophy.
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