A New York Times bestseller when it appeared in 1989, Roger Penrose's The Emperor's New Mind was universally hailed as a marvelous survey of modern physics as well as a brilliant reflection on the human mind, offering a new perspective on the scientific landscape and a visionary glimpse of the possible future of science. Now, in Shadows of the Mind, Penrose offers another exhilarating look at modern science as he mounts an even more powerful attack on artificial intelligence. But perhaps more important, in this volume he points the way to a new science, one that may eventually explain the physical basis of the human mind.
Penrose contends that some aspects of the human mind lie beyond computation. This is not a religious argument (that the mind is something other than physical) nor is it based on the brain's vast complexity (the weather is immensely complex, says Penrose, but it is still a computable thing, at least in theory). Instead, he provides powerful arguments to support his conclusion that there is something in the conscious activity of the brain that transcends computation--and will find no explanation in terms of present-day science. To illuminate what he believes this "something" might be, and to suggest where a new physics must proceed so that we may understand it, Penrose cuts a wide swathe through modern science, providing penetrating looks at everything from Turing computability and Godel's incompleteness, via Schrodinger's Cat and the Elitzur-Vaidman bomb-testing problem, to detailed microbiology. Of particular interest is Penrose's extensive examination of quantum mechanics, which introduces some new ideas that differ markedly from those advanced in The Emperor's New Mind, especially concerning the mysterious interface where classical and quantum physics meet. But perhaps the most interesting wrinkle in Shadows of the Mind is Penrose's excursion into microbiology, where he examines cytoskeletons and microtubules, minute substructures lying deep within the brain's neurons. (He argues that microtubules--not neurons--may indeed be the basic units of the brain, which, if nothing else, would dramatically increase the brain's computational power.) Furthermore, he contends that in consciousness some kind of global quantum state must take place across large areas of the brain, and that it within microtubules that these collective quantum effects are most likely to reside.

For physics to accommodate something that is as foreign to our current physical picture as is the phenomenon of consciousness, we must expect a profound change--one that alters the very underpinnings of our philosophical viewpoint as to the nature of reality. Shadows of the Mind provides an illuminating look at where these profound changes may take place and what our future understanding of the world may be.

罗杰-彭罗斯的《皇帝的新思维》在1989年出版时是《纽约时报》的畅销书，被普遍誉为对现代物理学的奇妙考察，以及对人类思维的精彩反思，为科学领域提供了一个新的视角，并对科学的可能未来进行了富有远见的一瞥。现在，在《心灵的阴影》中，彭罗斯对现代科学进行了又一次令人振奋的审视，他对人工智能进行了更有力的攻击。但也许更重要的是，在这一卷中，他为一门新的科学指明了方向，这门科学最终可能解释人类思维的物理基础。

彭罗斯认为，人类心灵的某些方面是超越计算的。这不是一个宗教论点（心灵是物理以外的东西），也不是基于大脑的巨大复杂性（彭罗斯说，天气是极其复杂的，但它仍然是一个可计算的东西，至少在理论上）。相反，他提供了强有力的论据来支持他的结论，即在大脑的意识活动中存在着超越计算的东西--而且在当今的科学中找不到解释。为了阐明他认为这个 "东西 "可能是什么，并建议新的物理学必须在哪里进行，以便我们能够理解它，彭罗斯对现代科学进行了大刀阔斧的研究，对从图灵可计算性和戈德尔的不完全性，通过薛定谔的猫和埃利茨尔-瓦德曼的炸弹测试问题，到详细的微生物学，提供了深入的观察。特别有趣的是彭罗斯对量子力学的广泛研究，它引入了一些与《皇帝的新思想》中的观点明显不同的新观点，特别是关于经典物理和量子物理相遇的神秘界面。但《心灵的阴影》中最有趣的变化也许是彭罗斯对微生物学的探索，他研究了细胞骨架和微管，这些微小的亚结构深藏在大脑的神经元中。(他认为微管--而不是神经元--可能确实是大脑的基本单位，如果没有其他原因，这将极大地提高大脑的计算能力）。此外，他认为，在意识中，某种全球量子状态必须在大脑的大片区域发生，而这些集体量子效应最有可能在微管内发生。

对于物理学来说，要容纳像意识现象这样与我们目前的物理图景相异的东西，我们必须期待一个深刻的变化--一个改变我们对现实的本质的哲学观点的基础。心灵的阴影》提供了一个具有启发性的视角，即这些深刻的变化可能发生在哪里，以及我们未来对世界的理解可能是什么。