1958年,彭罗斯在剑桥大学于知名代数学家与几何学家约翰·托德(英语:J. A. Todd)(John A. Todd)指导下获得博士学位;其博士论文题目为《代数几何学中的张量方法》(Tensor methods in algebraic geometry)。1965 年,彭罗斯与物理学家史蒂芬·霍金在剑桥大学证明了奇点(例如黑洞)可以从毁坏中的巨星体的重力坍缩现象中形成。[4]
彭罗斯撰写了探讨基础物理与人类(或者动物)意识之间联系的一些书籍。在《皇帝新脑》(1989)一书中,他声称已知的物理定律不足以解释意识现象。彭罗斯提议新物理学所具有的特性应该能填补经典物理学和量子力学(他本人称之为正确的量子引力理论)之间的理论沟壑。彭罗斯使用图灵停机问题的变体(比如,考虑只有 ON 和 OFF 两个状态的机器,当给定的图灵机停机时,系统状态被置为 ON;当图灵机运行时,系统则被置为 OFF。如此,系统状态将完全取决于图灵机本身。但是并没有算法上可行的方法来确定图灵机是否停机)来说明一个确定性的系统并不需要一定是图灵可计算的(从算法角度讲可进行有效计算的)。
作为对《皇帝新脑》所受到的负面评价的回应,彭罗斯随后出版了《意识的阴影》(Shadows of the Mind, 1994)和《庞大,渺小,及人类意识》(The Large, the Small and the Human Mind, 1997)。在这些书中,他还引用了来自麻醉专家史都华·哈默洛夫的观察。
彭罗斯和史都华·哈默洛夫认为意识是微管中量子引力效应的结果。该过程被他们称为 Orch-OR(orchestrated objective reduction,暂译:谐客观化归)。此后,在《物理评论E》上,马克斯·泰格马克发文指出,微管中神经元激发和兴奋的时间尺度以最少 10,000,000,000 倍的因子慢于量子退相干时间。[9]马克斯·泰格马克的论文受到了广泛接受,有文章如此总结:“没有卷入这场争斗的物理学家们——比如 IBM 的 Jone A. Smolin——认为文中的计算解决了长久以来的怀疑。‘我们拥有的并不是一颗接近绝对零度的大脑。从合理性上来讲人类大脑不可能以量子方式进化’”。[10]马克斯·泰格马克的论文被彭罗斯-哈默洛夫的批评者们广泛引用。
物理学家 Scott Hagan、Jack Tuszynski 和史都华·哈默洛夫也在《物理评论E》上发文回应马克斯·泰格马克[11],声称马克斯·泰格马克检验的并不是 Orch-OR 模型,而是他自己构造的模型:马克斯·泰格马克的计算中涉及的量子叠加态(the superpositions of quanta)以24纳米分隔,而非 Orch-OR 所要求的小的多的分隔。按照 Orch-OR 规定的量子叠加态进行运算之后,史都华·哈默洛夫的团队宣布新的量子退相干所需的时间尺度要比马克斯·泰格马克的结果大7个级数。但这个结果依然比所需的时间少了25毫秒——如果想要使量子过程如同 Orch-OR 所描述的那样,能够和40赫兹的伽玛同步产生关联的话。为了弥补这一环节,史都华·哈默洛夫等人做了一系列假设和提议。首先他们假设微管内部可以在液态和凝胶态之间互相转换。在凝胶状态下,他们进一步假设水的电偶极子会沿着微管外围的微管蛋白同向排列。史都华·哈默洛夫认为这种有序排列的水将会屏蔽微管蛋白中任何量子退相干过程。每个微管蛋白还会从微管中延伸出一条带负电荷的“尾巴”,从而可以吸引带正电荷的离子。这可以进一步屏蔽量子退相干的过程。除此之外,还有推测认为微管可在生物能的驱使下进入相干态。
Penrose. The Road to Reality: A Complete Guide to the Laws of the Universe. London: Jonathan Cape. 2004. ISBN 978-0-224-04447-9. (hardcover), ISBN 978-0-09-944068-0 (paperback).
NobelPrize.org. The Nobel Prize in Physics 2020. THE NOBEL PRIZE. Nobel Media AB 2020. 2020-10-06 [2020-10-06]. (原始内容存档于2021-04-24) (英语). one half awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity"
Boolos, George, et al. 1990. An Open Peer Commentary on The Emperor's New Mind. Behavioral and Brain Sciences 13 (4) 655.
Davis, Martin 1993. How subtle is Gödel's theorem? More on Roger Penrose. Behavioral and Brain Sciences, 16, 611-612. Online version at Davis' faculty page at http://cs.nyu.edu/cs/faculty/davism/ (页面存档备份,存于互联网档案馆)
Putnam, Hilary 1995. Review of Shadows of the Mind. In Bulletin of the American Mathematical Society 32, 370–373(also see Putnam's less technical criticisms in his New York Times review (页面存档备份,存于互联网档案馆))
Sources that indicate Penrose's argument is generally rejected:
In an article at 存档副本. [2010-10-22]. (原始内容存档于2001-01-25). L.J. Landau at the Mathematics Department of King's College London writes that "Penrose's argument, its basis and implications, is rejected by experts in the fields which it touches."
Sources that also note that different sources attack different points of the argument:
Princeton Philosophy professor John Burgess writes in On the Outside Looking In: A Caution about Conservativeness (页面存档备份,存于互联网档案馆) (published in Kurt Gödel: Essays for his Centennial, with the following comments found on pp. 131–132 (页面存档备份,存于互联网档案馆)) that "the consensus view of logicians today seems to be that the Lucas–Penrose argument is fallacious, though as I have said elsewhere, there is at least this much to be said for Lucas and Penrose, that logicians are not unanimously agreed as to where precisely the fallacy in their argument lies. There are at least three points at which the argument may be attacked."
Dershowitz, Nachum 2005. The Four Sons of Penrose (页面存档备份,存于互联网档案馆), in Proceedings of the Eleventh Conference on Logic Programming for Artificial Intelligence and Reasoning(LPAR; Jamaica), G. Sutcliffe and A. Voronkov, eds., Lecture Notes in Computer Science, vol. 3835, Springer-Verlag, Berlin, pp. 125–138.
Marvin Minsky. "Conscious Machines." Machinery of Consciousness, Proceedings, National Research Council of Canada, 75th Anniversary Symposium on Science in Society, June 1991.