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Los viajes en el tiempo y el universo de Einstein
En el universo newtoniano, el viaje en el tiempo era una fantasía inconcebible. Sin embargo, en determinadas condiciones, en el universo de Einstein esta paradoja puede hacerse realidad. Richard Gott, astrofísico de la Universidad de Princeton y uno de los más destacados investigadores de esta materia, nos acompaña en un fascinante periplo hasta los límites más sorprendentes de la imaginación y la ciencia: ¿qué haríamos si dispusiéramos de una máquina del tiempo?, ¿nos lanzaríamos a un recorrido turístico por los siglos futuros?, ¿podríamos regresar al pasado y alterar el curso de la historia?
Richard Gott comienza describiendo cómo algunas obras clásicas de ciencia-ficción - desde La máquina del tiempo de H.G. Wells hasta la serie televisiva Star Trek— anticiparon, con gran agudeza, algunas propuestas de la física contemporánea. Explica a continuación que los viajes al futuro no sólo son posibles (tal como Einstein demostró), sino que ya han sucedido realmente, pues los astronautas que hasta ahora han salido al espacio de hecho han envejecido ligeramente menos que el resto de los humanos. El autor examina después si, dadas determinadas circunstancias, es posible viajar al pasado. Pero quizá lo más sorprendente de este libro, tan apasionante como riguroso, radica en el hecho de que el estudio de los viajes en el tiempo puede aportar datos para una nueva teoría sobre el origen del universo.
Richard Gott comienza describiendo cómo algunas obras clásicas de ciencia-ficción - desde La máquina del tiempo de H.G. Wells hasta la serie televisiva Star Trek— anticiparon, con gran agudeza, algunas propuestas de la física contemporánea. Explica a continuación que los viajes al futuro no sólo son posibles (tal como Einstein demostró), sino que ya han sucedido realmente, pues los astronautas que hasta ahora han salido al espacio de hecho han envejecido ligeramente menos que el resto de los humanos. El autor examina después si, dadas determinadas circunstancias, es posible viajar al pasado. Pero quizá lo más sorprendente de este libro, tan apasionante como riguroso, radica en el hecho de que el estudio de los viajes en el tiempo puede aportar datos para una nueva teoría sobre el origen del universo.
312 pages, Paperback
First published January 1, 2001
375 people are currently reading
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About the author
J. Richard Gott III
8 books55 followersJohn Richard Gott III is a professor of astrophysical sciences at Princeton University. He is known for developing and advocating two cosmological theories with the flavour of science fiction: Time travel and the Doomsday argument.
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Displaying 1 - 30 of 110 reviews
January 6, 2008
I read this book and I need to re-read it again. This is one of those books that after you read it the first time, you are completely enlightened. You know you probably missed some important details so when you read it a second time, everything you missed pops out at you. For anybody really wanting to understand the different theories behind time travel, this book is for you. There were times when I just sat and pondered about what I just read for about an hour.
February 3, 2019
We instinctively know what time travel is, but how would you define it in physical terms? How is time travel to the past different from time travel to the future? And does it fit in our universe? If not, how can we know about the future?
Author tries to answer these questions in a graphic way, and he succeeds! The book also takes a suprising turn towards the end, making it an extra satisfying read.
Author tries to answer these questions in a graphic way, and he succeeds! The book also takes a suprising turn towards the end, making it an extra satisfying read.
February 24, 2025
Fun book that tries to minimize the actual physics of time travel and provide explanations more at a conceptual level.
Time travel to the future is well established theoretically and author provides an accessible illustration of the concept.
Time travel to the past is contested - author describes some mechanisms by which it could work, namely traveling in circular paths around cosmic strings, wormholes and warpdrives.
Cosmic strings are apparently like the superstrings of string theory, except they have have a very small thickness (unlike the superstrings of zero thickness).
Yes, just nod your head along - there are probably only like 7 people in the world who understand string theory.
Wormholes and warpdrives are those tunnels through spacetime. So, instead of traveling through the "curvature of spacetime" - you take a shortcut. So, instead of going around the mountain you tunnel through it.
This concept makes a little more intuitive sense than multidimensional "strings" (whether cosmic or superstrings) but apparently requires some negative mass stuff whose existence is still not proven while cosmic strings require only positive mass stuff. (Not that cosmic or superstrings are proven either).
Also, while one can see intuitively how wormholes it would result in faster than light travel, the explantation of time traveling through it means moving them wormholes around which was a little less intuitive.
Then there is one of the foundational question of physics - what was there before the universe? Here, the author ties time travel to the origin of universe.
Apparently, the universe is its own mother curving back in time to form itself. Every event has a preceding event and there is no earliest event.
There's also a final digression onto the topic of predicting the period of existence of literally anything in the universe.
Not sure how it relates to time travel but the author calls it the "The 95 Percent Copernican Argument" and states that everything will exist for 1/39th to 39 times its existing life.
So humans, currently existing for around 200,000 years will exist for another 5100 to 7.8M years and thereby we should start colonizing Mars ASAP (though with 5100 years, I think we can chill for a bit).
Overall, the book was fun trying to bend (just like spacetime, eh?) my imagination to visualize how exactly it would work and coming short over and over again.
Time travel to the future is well established theoretically and author provides an accessible illustration of the concept.
Time travel to the past is contested - author describes some mechanisms by which it could work, namely traveling in circular paths around cosmic strings, wormholes and warpdrives.
Cosmic strings are apparently like the superstrings of string theory, except they have have a very small thickness (unlike the superstrings of zero thickness).
Yes, just nod your head along - there are probably only like 7 people in the world who understand string theory.
Wormholes and warpdrives are those tunnels through spacetime. So, instead of traveling through the "curvature of spacetime" - you take a shortcut. So, instead of going around the mountain you tunnel through it.
This concept makes a little more intuitive sense than multidimensional "strings" (whether cosmic or superstrings) but apparently requires some negative mass stuff whose existence is still not proven while cosmic strings require only positive mass stuff. (Not that cosmic or superstrings are proven either).
Also, while one can see intuitively how wormholes it would result in faster than light travel, the explantation of time traveling through it means moving them wormholes around which was a little less intuitive.
Then there is one of the foundational question of physics - what was there before the universe? Here, the author ties time travel to the origin of universe.
Apparently, the universe is its own mother curving back in time to form itself. Every event has a preceding event and there is no earliest event.
There's also a final digression onto the topic of predicting the period of existence of literally anything in the universe.
Not sure how it relates to time travel but the author calls it the "The 95 Percent Copernican Argument" and states that everything will exist for 1/39th to 39 times its existing life.
So humans, currently existing for around 200,000 years will exist for another 5100 to 7.8M years and thereby we should start colonizing Mars ASAP (though with 5100 years, I think we can chill for a bit).
Overall, the book was fun trying to bend (just like spacetime, eh?) my imagination to visualize how exactly it would work and coming short over and over again.
September 26, 2013
No book is without its charm although this one comes pretty close. Granted, diehard and gullible enthusiasts of space travel no doubt think differently but for the more skeptical they will find little worthwhile here except a gift for explaining the theory of relativity--both special and general relativity--with clarity and simplicity that few can and thus the latter part of the fourth chapter makes the book worthy of the purchase. For those seeking a book that will advocate the resumption of space travel to secure the longevity of the human race as this one does in the last chapter it can be imagined that more thoughtful explanations of the benefits of such exploration are to be found. Likewise, those who want to believe that time travel has any realistic basis will be sorely disappointed. Instead, one will find competitive Gott, cape crusader with his friend Li Xin Li (the former you can, to use an epithet, call batman and the latter Robin) writing a book to lay claim of some very speculative theories. There is one in which Gott, so eager to be the next Newton of time travel, deals with orbiting two cosmic strings that will lead one to the past--Gott himself wants full acclaim as the inventor of this idea. The other, his magnum opus which he shares with his counterpart Robin is figuring out the fact that there will be no explosion if one quickly accelerates in and out of the doors of Misner space, and thus one is now free to leap into time with this. Well I am busy today but I will definitely do it tomorrow. Oh yes, the cape crusaders shook hands with each other in their zeal at finding this an achievable goal. You can learn about their flourishing relationship in the content of this book. Yes the book does explore half a dozen other ways to go into the future and past such as the plausibility of engineering wormholes but frankly it is not worth ones time. The reality is that talk of time travel is an absurdity for a world that has done little that is remarkable beyond flight travel to the moon. We are in the stone ages and yet astrophysists are making mathematical formulas of scenarios that will be implausible even hundreds of years into the future at best and seeking acclaim for it. It has little sense.
February 19, 2008
I enjoyed this book about the physics of time travel, although at times I felt like the author was dealing with some pretty speculative stuff and presenting it pretty confidently as fact.
For instance, he describes a method of creating a "time machine" that would, in theory, allow a spaceship to reach a destination faster than light. To set up the process, you position two cosmic strings of infinite length near each other. Oh, is that all I need? Two cosmic strings of infinite length. Let me check in the basement for those. Meanwhile, I will continue with my money making plan of finding a magical goblin that craps Fabergé eggs.
In another section of the book, there is a lengthy discussion about predicting the duration of things (like lives, or civilizations, or planets) based on probability and the idea that we're not at some "special" point in time (like the Copernican view that Earth doesn't occupy a "special" place in the cosmos). This method allows the author to predict that, for example, the United States is likely to exist for a duration of somewhere between 5.7 years and 8736 years.
The ultimate point of describing this method of predicting the future is to exhort people to invest resources into the space program, with the goal in mind of colonizing space, in order to increase the likelihood of the survival of humanity. This point I tend to agree with, although the "Copernican" method of predicting the future seems kinda sketchy.
Generally, there is some good material here, particularly in the chapters related to how physics has evolved throughout history, and how our view of time has changed as a result.
For instance, he describes a method of creating a "time machine" that would, in theory, allow a spaceship to reach a destination faster than light. To set up the process, you position two cosmic strings of infinite length near each other. Oh, is that all I need? Two cosmic strings of infinite length. Let me check in the basement for those. Meanwhile, I will continue with my money making plan of finding a magical goblin that craps Fabergé eggs.
In another section of the book, there is a lengthy discussion about predicting the duration of things (like lives, or civilizations, or planets) based on probability and the idea that we're not at some "special" point in time (like the Copernican view that Earth doesn't occupy a "special" place in the cosmos). This method allows the author to predict that, for example, the United States is likely to exist for a duration of somewhere between 5.7 years and 8736 years.
The ultimate point of describing this method of predicting the future is to exhort people to invest resources into the space program, with the goal in mind of colonizing space, in order to increase the likelihood of the survival of humanity. This point I tend to agree with, although the "Copernican" method of predicting the future seems kinda sketchy.
Generally, there is some good material here, particularly in the chapters related to how physics has evolved throughout history, and how our view of time has changed as a result.
October 10, 2023
Relatively accessible to read, but could have done with shorter chapters and more diagrams.
December 13, 2018
Great book. Perfect starter book to anyone interested in time travel. It posits many of the theories and paradoxes of time travel while being quite informative. The book may be tough for some readers if not of a science background, but it has excellent metaphors that help the reader along.
July 30, 2016
traveling through time is just a technological problem .... after reading this book you will realize that there are way more methods to travel through time than you have ever thought ...
January 13, 2016
ريفيو طويل ..
دعني أخبرك بسر،أنا و أنت و الجميع مسافرون عبر الزمن ،كيف هذا ؟ سأخبرك لاحقا و لكن الأن سوف أشاركك بعض الأفكار المتفرقة عن موضعنا هذا .
دعني أتحدث عن الزمن قليلا ، مفهوم البعد الرابع اي الزمن ظهر لاول مرة في رواية آله الزمن عام 1895 علي يد هربرت جورج ويلز ، اي انه ظهر أدبيا أولا ثم تنبنته الفيزياء ، أليس ذلك مشوقا ؟. حسنا دعني أنبهك أن هناك فرقا جوهريا بين البعد الزماني و الابعاد المكانية الثلاثة ، فالبعد الزماني له إشارة سالبة .
علم الفيزياء حاليا يعترف بأربع أبعاد محسوسة كما سبق ذكره و لكن هناك من يعتقد بأن هناك بعدين زمانين لا بعد واحد ، و أنا من مؤيدي تلك الفكرة ، فالابوريجنين ×سكان استراليا الاصليون اعتقدوا بوجود بعد زماني أخر و هو ×بعد الحلم× ، نهايك عي انه من الممكن أن نكتشف مستقبيلا ابعاد أخري ربما تكون غير محسوسة .
تخيل معي عالما أحادي الابعاد أو ثنائي الابعاد ؟ ساترك شرح هذه النقطة للكتاب فهي مذكورة فيه بأستفاضة .
أفكرت في سبب وجود 4 أبعاد ؟ ربما يكون السر وراء وجودها هو الجاذبية ×استنادا علي أفكار اينشتاين×
تبعا لنظرية النسبية الخاصة لا يمكن السفر عبر الزمكان للماضي لان ذلك ينافي حقيقة أن سرعة الضوء هي السرعة الوحيدة المطلقة في الكون .
أسمعت يوما عن مبدأ عدم اليقين ؟ الفيزياء الكمية؟ الفوتون ؟ الثقب الدودي ؟ الثقب الاسود؟ نظرية ماكسويل ؟ نظرية الاوتار الفائقة ؟
العجيب أن نظرية الاوتار الفائقة ×بدون التطرق لها×تقترح وجود 11 بعدا , واحد زماني ، 3 ابعاد مكانية ، 7 ابعاد ملتوية .
أسمعت عن مسرعات الجسيمات ؟ جسيمات الميون ؟ جسيمات الكوارك ؟ المادة المضادة ؟
تتسأل لما أطرح كل هذه الاسئلة ، اطرحها لانها هي البنية الرئيسية التي يترتب عليها نشوء مفهوم السفر عبر الزمن .
نرجع لحديثنا عن أننا جميعا مسافرون عبر الزمن ، نعم نلك حقيقة فنحن نسافر عبر الزمن بسرعة ثانية بثانية أي بشكل طبيعي ، و لكننا ايضا نستطيع السفر بشكل غير طبيعي دعني أوضح ذلك
تبعا لاينشتاين :الزمن يتبأطي بالنسبة للاجسام المتحركة , اي أنه كلما زادت سرعة الجسم يزداد تبأطي الزمن فيصبح ذلك نوع من السفر عبره للمستقبل
بعضهم أعترض قائلا ، لا نستطيع أن نقرب جسما من سرعة الضوء ، الم يسمع القائل عن مسرعات الجسيمات العظمي ففي معهد فيرمي تم تسريع البروتونات الي 99,999946 في المائة من سرعة الضوء ، اي أنها حيز الامكان ولكن يكمن العيب في إمكانيتنا في تطبيق هذه العملية علي كتلة كبيرة نسبيا ككتلة الانسان , لم اقنعك ؟ حسنا و إن اخبرتك أن احدهم بالفعل سافر عبر الزمن للمستقبل ؟ رائد الفضاء الروسي سيرجي اندييف قصي 748 يوما في الفضاء و تجاوزت سرعته 17000 ميل في الساعة اي ان تلك السرعة تساوي 0,00254 من سرعة الضوء و لكن بلغ عنها أن عمره تناقص بمقدار 1 علي 50 عن العمر الذي كان سيبلغه علي الارض ، رغم كونها ضئيلة جدا الا انها حقيقة تثبت إمكانية السفر .
حسنا تعالي معي نفكر في السفر عبر الزمن للماضي و لكن فكر فيه كأنك تشاهد الماضي لا تزوره ، اتعلم انك إذا راقبت نجم ألفا قنطروس فأنك ما تشاهده هو ماضيه و ليس حاضره فهو يبعد عنا 4 سنوات ضوئية ، و مجرة أندروميدا تبعد عنا ميلوني سنة ضوئية اي ان ما تراه عندما تراقبها هو ماضيها منذ مليوني عام ، ببساطة اي أن التليسكوب أداة زمن .
اتريد أن تري نفسك في الماضي ؟ بسيطة قف علي بعد خمسة أقدام من المرآه ، الصورة التس تراها ليست صورتك الحاليا بل هي صورة من ماضيك لأكون أكثر دقة هي صورتك منذ 10 نانو ثانية
أما زيارة الماضي فهو أكثر تعقيدا فتبعا للنسبية الخاصة هو مستحيل و لكن ظهرت عدة نظريات أخري تسمح بحدوثها ، كطبيعة الزمكان المنحنية ، تقوس الكون ، الاوتار الكونية و غيرها كثير ..
دعنا لا ننسي أن الكثير مما نحن فيه الأن كان في البدء مستحيلا.
الكتاب من أروع ما قرأت في موضوعه , لدرجة أنه الكتاب الوحيد الذي قرأته مرتين
ستجد فائدة لا مثيل لها فيه .
أنصح به و بشدة
July 2, 2021
في كون أينشتاين اصبح السفر عبر الزمن الى المستقبل فعلاً في عداد المتاح .لقد وضح عمل اينشتاين ان الزمان يمكن معالجته رياضيًا كبعد رابع . وبالمقارنة ان سطح الارض ثنائي الابعاد. اما الكون فإنه رباعي الابعاد .
السفر عبر الزمن الى المستقبل، بالامكان زيارة الارض بعد ألف عام من الان ، لقد بين آينشتاين كيفية فعل ذلك ، ان يستقل سفينة فضاء وتيمم شطر نجم يبعد اقل قليلًا من ٥٠٠ سنة ضوئية والعودة منها قاطعًا رحلتي الذهاب والعودة بسرعة ٩٩،٩٩٥ ٪من سرعة الضوء ، وعند العودة للارض ثانيةً سيكون قد انقضى من عمرها ألف سنة ، بينما لن يزيد عمر المسافر الا بمقدار عشر سنوات . في المقدور تسريع البروتونات لتصل سرعتها الى ٩٩.٩٩٥٪ من سرعة الضوء . ان المشكلة لا تعدو ان تكون مسألة تكلفة ، فالبروتونات لا تزن كثيراً ومن ثم فإن تعجيلها الى سرعات عالية غير باهظ التكاليف. غير ان الكائن البشري يزن قدر وزن البروتون بنحو ٤٠ أكتليون مرة وعلى ذلك فسيكون تعجيل جسمه بمعيار الطاقة اكثر كلفة بما لا يقاس .
السفر عبر الزمان الى الماضي ، اذا راقبنا ألفا قنطورس والذي يبعد عنا بأربع سنين ضوئية ، فإننا لا نشاهده كما يبدو اليوم ، وإنما كما كان يبدو منذ اربعة اعوان خلت ، ونرى نجم الشعري اليمانية على مسافة ٩سنوات ضوئية منا كما كان يتألق منذ تسع سنوات ، واذا تطلعت الى مجرة اندروميدا والتي يفصلنا عنها مليونا سنة ضوئية ، فإنك تراها كما لاحت منذ مليوني عام ، في ذلك الوقت حينما كان أسلافنا الاوائل من سلالة الانسان الماهر في الاعمال اليدوية "هوموهبليس "يدبون على الارض . وهكذا كلما رنونا الى مسافات ابعد كلما أوغلنا في التطلع الى الماضي . ان الخلفية الاشعاعية للموجات الكونية متناهية الصغر والتي تتكون من موجات متناهية الصغر من الفوتونات تنهمر على الارض من كل ارجاء السماء ، وهي التي تخلفت من مرحلة طفولة الكون حينما كان في درجة حرارة عالية ، وتأتي هذه الفوتونات الينا مباشرة من نحو ١٣ بليون سنك مضت ، عندما كان عمر الكون الوليد .
من الصعوبة التصديق بخروج الكون من العدم بمعناه الحرفي . كيف يمكن بمقدور العدم ان يعرف عن قوانين الفيزياء ، حقيقة ربما اعتبرت محاولة جعل الكون يأتي من لا شيء محاولة شاذة ، لأن العدم هو الشيء الذي يبدو بحكم التعريف غير موجود ، وربما كان السؤال عن كيفية خلق الكون من العدم سؤالًا خاطئًا ، ربما لم تكن تلك هي الكيفية التي ظهر بها الكون .
السفر عبر الزمن الى المستقبل، بالامكان زيارة الارض بعد ألف عام من الان ، لقد بين آينشتاين كيفية فعل ذلك ، ان يستقل سفينة فضاء وتيمم شطر نجم يبعد اقل قليلًا من ٥٠٠ سنة ضوئية والعودة منها قاطعًا رحلتي الذهاب والعودة بسرعة ٩٩،٩٩٥ ٪من سرعة الضوء ، وعند العودة للارض ثانيةً سيكون قد انقضى من عمرها ألف سنة ، بينما لن يزيد عمر المسافر الا بمقدار عشر سنوات . في المقدور تسريع البروتونات لتصل سرعتها الى ٩٩.٩٩٥٪ من سرعة الضوء . ان المشكلة لا تعدو ان تكون مسألة تكلفة ، فالبروتونات لا تزن كثيراً ومن ثم فإن تعجيلها الى سرعات عالية غير باهظ التكاليف. غير ان الكائن البشري يزن قدر وزن البروتون بنحو ٤٠ أكتليون مرة وعلى ذلك فسيكون تعجيل جسمه بمعيار الطاقة اكثر كلفة بما لا يقاس .
السفر عبر الزمان الى الماضي ، اذا راقبنا ألفا قنطورس والذي يبعد عنا بأربع سنين ضوئية ، فإننا لا نشاهده كما يبدو اليوم ، وإنما كما كان يبدو منذ اربعة اعوان خلت ، ونرى نجم الشعري اليمانية على مسافة ٩سنوات ضوئية منا كما كان يتألق منذ تسع سنوات ، واذا تطلعت الى مجرة اندروميدا والتي يفصلنا عنها مليونا سنة ضوئية ، فإنك تراها كما لاحت منذ مليوني عام ، في ذلك الوقت حينما كان أسلافنا الاوائل من سلالة الانسان الماهر في الاعمال اليدوية "هوموهبليس "يدبون على الارض . وهكذا كلما رنونا الى مسافات ابعد كلما أوغلنا في التطلع الى الماضي . ان الخلفية الاشعاعية للموجات الكونية متناهية الصغر والتي تتكون من موجات متناهية الصغر من الفوتونات تنهمر على الارض من كل ارجاء السماء ، وهي التي تخلفت من مرحلة طفولة الكون حينما كان في درجة حرارة عالية ، وتأتي هذه الفوتونات الينا مباشرة من نحو ١٣ بليون سنك مضت ، عندما كان عمر الكون الوليد .
من الصعوبة التصديق بخروج الكون من العدم بمعناه الحرفي . كيف يمكن بمقدور العدم ان يعرف عن قوانين الفيزياء ، حقيقة ربما اعتبرت محاولة جعل الكون يأتي من لا شيء محاولة شاذة ، لأن العدم هو الشيء الذي يبدو بحكم التعريف غير موجود ، وربما كان السؤال عن كيفية خلق الكون من العدم سؤالًا خاطئًا ، ربما لم تكن تلك هي الكيفية التي ظهر بها الكون .
September 28, 2021
This is not a badly written book, and it has some good background material on Einstein's theories of relativity and how they could be used to achieve a sort of time travel to the future, namely by traveling into space a few light years and returning at close to the speed of light. The book title is misleading, however, because the majority of the time travel mechanisms in this book are based on more recent theories than Einstein's. Gott proposes time travel possibilities mostly using unproven fantasy land theories prevalent in today's physics like string theory, infinite parallel universes, cosmic strings, and other unproven phenomena.
So Gott's theories to support time travel are relatively bizarre, requiring things like multiple unseen dimensions around us, wormholes between universes, self-creating universes, and other unobservable marvels. Current physics supports these theories because they seem to be mathematically possible, in lieu of any actual evidence. And the actual time machines Gott proposes are so impossibly large or complicated that even a super civilization would be challenged to build them.
There is also a strange chapter on the Copernican principle which I am not sure how it relates to the rest of the book. And it is somewhat useless because of the large range of its predictions.
Overall my impression of this book is it is similar to science fiction. Interesting concepts, but purely fantasy at this point in time.
So Gott's theories to support time travel are relatively bizarre, requiring things like multiple unseen dimensions around us, wormholes between universes, self-creating universes, and other unobservable marvels. Current physics supports these theories because they seem to be mathematically possible, in lieu of any actual evidence. And the actual time machines Gott proposes are so impossibly large or complicated that even a super civilization would be challenged to build them.
There is also a strange chapter on the Copernican principle which I am not sure how it relates to the rest of the book. And it is somewhat useless because of the large range of its predictions.
Overall my impression of this book is it is similar to science fiction. Interesting concepts, but purely fantasy at this point in time.
August 9, 2015
This book is more than just another popular treatment of special and general relativity and quantum mechanics. Gott applies these theories to time travel in a 'not-wrong' fashion, i.e., consistently with we already know to be true. He discusses the theoretical possibility of time travel to the future and to the past (spoiler: both may be possible), and even describes the construction of time machines that do not violate the laws of physics as we now understand them (spoiler: you may need the energy of an entire galaxy). The book is entertaining and the exposition mostly clear. One could argue it's a must read for us fans of time travel fiction. Gott may take himself more seriously than you will, but it's a fun read.
March 18, 2018
This is a very good book on physics and time travel by somebody who has written a lot of influential papers on the subject. The beginning is very witty and frames the questions through the use of time travel in fiction and film but then it quickly delves into hard science. Early chapters will just be a review of Einstein for many people, but the later chapters are filled with interesting ideas that I wasn't really familiar with. I think the lst chapter, which is about predicting the future, really doesn't belong in this book, but otherwise I have very few criticisms.
March 8, 2021
This book is one of the best books that seriously explores time travel using actual (and somewhat possible applications of futuristic) physics. The author also digs deep into statistical data and explores the average lifespan of a species, warns never to take a maiden voyage on a ship or aircraft, and has an extensive notes section that was just as interesting as the main book itself. It helps too have some rudimentary knowledge of science, but there’s really no math and if you are willing to be patient, you will learn a lot of cool stuff!
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November 8, 2010Professor Gott starts with the familiar paradox of a time traveler going back and killing a grandparent, adds Einstein's general theory of relativity, and walks the reader through much of current physics theory while seeking ways time travel might be permitted. Along the way, he manages to use almost no mathematics through a set of simple, expressive diagrams. An excellent popular science book!
January 13, 2018
One of the two best non-fiction books I have ever read. Read it several years ago and it continues to influence my thinking. This book touched me not just intellectually, but surprisingly spiritually as well. It is one of two books I always recommend for anyone seeking a higher understanding and connection with the eternal. There truly can be a spiritual aspect to science.
March 1, 2023
Read this when I was 10. It’s a fun book that explores Einstein’s theories in concise and easy to understand ways. The author has a sense of humor too, so it’s a far cry from most dry nonfiction. A nice starter book for those interested in the subject- it is an enjoyable read while also having some substance regarding the depth and complexity of relativity.
August 18, 2017
Un librito muy interesante que ofrece mucho más de lo que esperaba y te deja con ganas de más.
December 18, 2025
Bu kitabı ilk kez lisede okuduğumda kaybolmuştum. Aradan geçen seneler sonrasında yine sonuna doğru kaybolduğumu görmek biraz hayal kırıklığına uğratsa da beni bilmediğim ve anlamadığım kısımları öğrenmeye yöneltti diyebilirim. Kitabın başındaki eylemsizlik, ivme ve sözde kuvvetler üzerinden kurulan anlatımı güçlü ve ikna edici buldum. Sabit hızla hareket ile hareketsizliğin ayırt edilemez olması, buna karşılık ivmenin (hız ya da yön değişimi) mutlaka hissedilmesi, Einstein’ın eşdeğerlik ilkesini sezgisel olarak iyi oturtuyor. Viraj alan araba örneği özellikle yerinde: ortada bana etki eden “gerçek” bir kuvvet olmasa bile, eylemsizliğimi koruma eğilimim nedeniyle sözde kuvvetleri deneyimlemek zorundayım. Yerçekimi hissinin ivmeyle aynı fiziksel yapıdan doğduğu fikri bu noktada gerçekten yerine oturuyor.
Ancak kitap ilerledikçe anlatı, karadelikler, evrenin ilk anları ve zaman yolculuğu gibi daha uç bölgelere kayıyor. Karadeliklerin ya da erken evrenin, fizik yasalarının sınırlarını test edebileceğimiz doğal ortamlar olarak ele alınması matematiksel olarak anlaşılır, fakat fiziksel karşılığı belirsiz. Zaman makineleri bağlamında söylenenler, büyük ölçüde “eğer mümkünse, ancak bu aşırı koşullarda olabilir” düzeyinde kalıyor; burada ikna edici bir mekanizmadan çok, olasılıkların haritası çiziliyor.
Kapalı zaman benzeri eğriler (CTC) bu belirsizliğin en yoğunlaştığı yer. CTC’ler, matematiksel olarak Einstein denklemlerinin izin verdiği çözümler olsa da, nedenselliği bozuyor, başlangıç koşullarını anlamsızlaştırıyor ve özellikle kuantum etkiler hesaba katıldığında ciddi kararlılık sorunları doğuruyor. “Denklem izin veriyor” ile “doğa bunu gerçekten gerçekleştiriyor” arasındaki mesafe burada fazlasıyla açılıyor. Kağıt üzerinde mümkün olan şey, fiziksel olarak güven vermiyor.
de Sitter uzayı da zaman sezgimi benzer biçimde zorladı. Pozitif kozmolojik sabit nedeniyle sürekli genişleyen bu uzay-zamanda olay ufuklarının varlığı, küresel bir “şimdi” kavramını ortadan kaldırıyor. Zaman, akıp giden tek bir çizgi olmaktan çıkıp, uzay-zamanın küresel geometrisine bağlı bir özellik hâline geliyor. Geleceğin bir kısmının yapısal olarak gözlemlenememesi, zaman ve nedensellik fikrini sezgisel olmaktan uzaklaştırıyor.
Bu noktadan sonra kitap, sezgisel ve öğretici bir genel görelilik anlatısından, teorik fiziğin sınırlarını yoklayan bir düşünce haritasına dönüşüyor. İlginç ve kışkırtıcı, ama fiziksel gerçeklik hissi benim için belirgin biçimde zayıflıyor. Buna rağmen kitap benim için önemli bir eşik oldu: zaman, nedensellik ve evrenin yapısı üzerine daha temelli ve felsefi sorular sormama neden oldu ve beni Julian Barbour’un The End of Time’ına, Tim Maudlin’in fizik felsefesi tartışmalarına ve nedensellik üzerine daha doğrudan metinlere yönlendirdi. Bu anlamda kitap, cevap vermekten çok, doğru soruları başka yerlerde aramama vesile oldu.
Ancak kitap ilerledikçe anlatı, karadelikler, evrenin ilk anları ve zaman yolculuğu gibi daha uç bölgelere kayıyor. Karadeliklerin ya da erken evrenin, fizik yasalarının sınırlarını test edebileceğimiz doğal ortamlar olarak ele alınması matematiksel olarak anlaşılır, fakat fiziksel karşılığı belirsiz. Zaman makineleri bağlamında söylenenler, büyük ölçüde “eğer mümkünse, ancak bu aşırı koşullarda olabilir” düzeyinde kalıyor; burada ikna edici bir mekanizmadan çok, olasılıkların haritası çiziliyor.
Kapalı zaman benzeri eğriler (CTC) bu belirsizliğin en yoğunlaştığı yer. CTC’ler, matematiksel olarak Einstein denklemlerinin izin verdiği çözümler olsa da, nedenselliği bozuyor, başlangıç koşullarını anlamsızlaştırıyor ve özellikle kuantum etkiler hesaba katıldığında ciddi kararlılık sorunları doğuruyor. “Denklem izin veriyor” ile “doğa bunu gerçekten gerçekleştiriyor” arasındaki mesafe burada fazlasıyla açılıyor. Kağıt üzerinde mümkün olan şey, fiziksel olarak güven vermiyor.
de Sitter uzayı da zaman sezgimi benzer biçimde zorladı. Pozitif kozmolojik sabit nedeniyle sürekli genişleyen bu uzay-zamanda olay ufuklarının varlığı, küresel bir “şimdi” kavramını ortadan kaldırıyor. Zaman, akıp giden tek bir çizgi olmaktan çıkıp, uzay-zamanın küresel geometrisine bağlı bir özellik hâline geliyor. Geleceğin bir kısmının yapısal olarak gözlemlenememesi, zaman ve nedensellik fikrini sezgisel olmaktan uzaklaştırıyor.
Bu noktadan sonra kitap, sezgisel ve öğretici bir genel görelilik anlatısından, teorik fiziğin sınırlarını yoklayan bir düşünce haritasına dönüşüyor. İlginç ve kışkırtıcı, ama fiziksel gerçeklik hissi benim için belirgin biçimde zayıflıyor. Buna rağmen kitap benim için önemli bir eşik oldu: zaman, nedensellik ve evrenin yapısı üzerine daha temelli ve felsefi sorular sormama neden oldu ve beni Julian Barbour’un The End of Time’ına, Tim Maudlin’in fizik felsefesi tartışmalarına ve nedensellik üzerine daha doğrudan metinlere yönlendirdi. Bu anlamda kitap, cevap vermekten çok, doğru soruları başka yerlerde aramama vesile oldu.
August 26, 2021
Zamanda yolculuk olasılığının, kendisi de bir astrofizikçi olan Richard Gott tarafından açıklanmaya çalışıldığı bu kitapta; sayın Gott' un bunu Einstein' ın kocaman bir fotoğrafı ve isminin olduğu bir kapakla sunmasına çok da anlam veremedim. Konunun kendisi yeterince hoş ve ilgi çekiciyken bunu Einstein' ı da ileri sürerek süslemeye çalışmak yazarın hem kendisine hem de konuya bir nebze haksızlık etmesi gibi geldi bana. Olmasa da olurmuş, olmasa da bu kitap yine zevkle okunurmuş.
Bu durumu anlamlı hâle getirmek isteyen editörün bir çabası olarak, kitabın içeriğinde, hemen ilk sayfalarda "Aklın Efendisi Einstein" başlıklı bir bölümle karşılaşıyoruz. Burada Einstein' ın yaşam hikayesi, genel görelilik ve özel görelilik hipotezleri, Newton, Marks ve Hubble' a da değinilerek kısaca anlatılmış. Editör Prof. Dr. Cengiz Yalçın' ı bu noktada ayrıca tebrik ediyorum. Kitabın asıl içeriğinde ise Zamanda Yolculuk Rüyası, evrenin boyutları, geçmiş ve geleceğe yolculuk olasılıkları, evrenin başlangıcı, zaman makinesi yapmanın-çalıştırmanın mantığı, kozmik şeritler, kuasarlar, satranç ve fizik yasaları arasındaki ilişki gibi meraklısı için son derece ilgi çekici konulara yer verilmiş. Tüm bu bilgiler de günlük hayattan benzetmeler, ilginç metaforlar kullanılarak anlatıldığı için anlaşılmaları gerçekten kolaylaştırılmış. Yine de "kolay" demiyorum, "kolaylaştırılmış" diyorum. Çünkü belli bir fizik ve biyoloji bilgisi birikimi olmadan anlaşılması yine de pek olası görünmüyor.
Hayatın farklı evrelerinde yeniden okunmasını da şiddetle tavsiye edebileceğim bir kitap. Hem bilimsel bilgi birikiminizin artmasına hem de tecrübe ve yaşanmışlıkla doğru orantılı olarak artacak "hayata, yaşama ve canlılığa farklı gözden bakabilme" yetinize bağlı olarak bazı şeyleri yeniden değerlendirebileceğinizi, her seferinde ufkunuzu daha geniş tutabileceğinizi düşünüyorum. Yazar ve bilim insanı J. Richard Gott genel itibariyle oldukça sıkı çalışan bir astrofizikçi ve kesinlikle ilginç bir insan. Fakat "Gelecekten Rapor" bölümünde bahsettiği, nüfus artışıyla ilgili bölüm ve bu artışın "herhangi bir şekilde" durdurulmasının çok da kötü bir fikir olmayacağına dair sözleri pek içime sinmedi. Kitapta yer alan bilgiye göre, bu, Nature' da bilimsel makaleleri yayımlanan bilim insanımız, aynı zamanda 1969'da Kopernik İlkesi' nden yola çıkarak Berlin Duvarı' nın ne zaman yıkılacağını hesaplayıp öngörmüş ve öngörüsü doğru çıkmış. Enteresan olay! Yazara göre Kopernik İlkesi' nden hareketle geleceği öngörebilmek olası ve bilimsel...
İnsan, evren ve zaman sırlı ve müphem. İnsanı, evreni ve zamanı çözmeye, anlamaya çalışmak ise heyecanlı ve zevkli.
Bu durumu anlamlı hâle getirmek isteyen editörün bir çabası olarak, kitabın içeriğinde, hemen ilk sayfalarda "Aklın Efendisi Einstein" başlıklı bir bölümle karşılaşıyoruz. Burada Einstein' ın yaşam hikayesi, genel görelilik ve özel görelilik hipotezleri, Newton, Marks ve Hubble' a da değinilerek kısaca anlatılmış. Editör Prof. Dr. Cengiz Yalçın' ı bu noktada ayrıca tebrik ediyorum. Kitabın asıl içeriğinde ise Zamanda Yolculuk Rüyası, evrenin boyutları, geçmiş ve geleceğe yolculuk olasılıkları, evrenin başlangıcı, zaman makinesi yapmanın-çalıştırmanın mantığı, kozmik şeritler, kuasarlar, satranç ve fizik yasaları arasındaki ilişki gibi meraklısı için son derece ilgi çekici konulara yer verilmiş. Tüm bu bilgiler de günlük hayattan benzetmeler, ilginç metaforlar kullanılarak anlatıldığı için anlaşılmaları gerçekten kolaylaştırılmış. Yine de "kolay" demiyorum, "kolaylaştırılmış" diyorum. Çünkü belli bir fizik ve biyoloji bilgisi birikimi olmadan anlaşılması yine de pek olası görünmüyor.
Hayatın farklı evrelerinde yeniden okunmasını da şiddetle tavsiye edebileceğim bir kitap. Hem bilimsel bilgi birikiminizin artmasına hem de tecrübe ve yaşanmışlıkla doğru orantılı olarak artacak "hayata, yaşama ve canlılığa farklı gözden bakabilme" yetinize bağlı olarak bazı şeyleri yeniden değerlendirebileceğinizi, her seferinde ufkunuzu daha geniş tutabileceğinizi düşünüyorum. Yazar ve bilim insanı J. Richard Gott genel itibariyle oldukça sıkı çalışan bir astrofizikçi ve kesinlikle ilginç bir insan. Fakat "Gelecekten Rapor" bölümünde bahsettiği, nüfus artışıyla ilgili bölüm ve bu artışın "herhangi bir şekilde" durdurulmasının çok da kötü bir fikir olmayacağına dair sözleri pek içime sinmedi. Kitapta yer alan bilgiye göre, bu, Nature' da bilimsel makaleleri yayımlanan bilim insanımız, aynı zamanda 1969'da Kopernik İlkesi' nden yola çıkarak Berlin Duvarı' nın ne zaman yıkılacağını hesaplayıp öngörmüş ve öngörüsü doğru çıkmış. Enteresan olay! Yazara göre Kopernik İlkesi' nden hareketle geleceği öngörebilmek olası ve bilimsel...
İnsan, evren ve zaman sırlı ve müphem. İnsanı, evreni ve zamanı çözmeye, anlamaya çalışmak ise heyecanlı ve zevkli.
December 24, 2019
Even though reading this book was a chore for me, I wouldn't have rated it this low before reading the section about predictions for the future. In previous sections of the book, I was interested in what was being said and learned some new things about quantum theory. The section about the beginning of the universe (the second to last section) was the main reason this book was a chore to read. I will be the first to admit that maybe I should have just skipped this section - I am not so much of a science or math person, but I understood it just enough to try to get through it. (This was a mistake. I didn't have fun.) Even with this section, I would not have rated the book much lower. However, the last section was maddening. Gott provided estimates for the longevity of things, sure, but the estimates were so broad as to be completely obvious. Yes, there's a 95% chance the United States will not last until the year 10736. I could have told you as much without using a lick of math. If you make a broad enough range for how long something will last, of course you're bound to be right. I think you're better served by my pet theory that you're 100% likely to either die or not die tomorrow. Was this section put in entirely to annoy the hell out of me??
August 31, 2025
This varies between being a layperson's look at time travel and a physics book. We go from the professor checking out SF paradox stories (he gives away the endings) to expounding on dropping different balls while in a moving rocket.
There are line graphs to explain curves, helixes and a ball tunnelling out of a dip and slope. I felt a few photos would not go amiss, especially of a galaxy or Mars, since we discuss a colony. The author explains that the first words spoken on the Moon were in English because Britain established a colony in America. We should set up a colony on Mars because who knows if a Martian colony group might go further than Earth's group. However, he wrongly says a colony once set up with maybe eight people would cost nothing thereafter - if would need all kinds of support.
This is interesting but unconvincing that we can time travel, however physic students may enjoy the read.
There are line graphs to explain curves, helixes and a ball tunnelling out of a dip and slope. I felt a few photos would not go amiss, especially of a galaxy or Mars, since we discuss a colony. The author explains that the first words spoken on the Moon were in English because Britain established a colony in America. We should set up a colony on Mars because who knows if a Martian colony group might go further than Earth's group. However, he wrongly says a colony once set up with maybe eight people would cost nothing thereafter - if would need all kinds of support.
This is interesting but unconvincing that we can time travel, however physic students may enjoy the read.
October 21, 2025
I read this book knowing that I’d have difficulty understanding the science in it. I took biology & chemistry in school, not physics and certainly not astrophysics. So I didn't understand a lot, although it’s quite clear that Princeton Professor J. Richard Gott knows his business. Despite being relatively clueless, I enjoyed Gott’s sense of humor, making references to time travel in our popular culture, including "Back to the Future," "Bill & Ted's Excellent Adventure" & Spock in the series, "Star Trek."
Bottom line: Time travel to the future possible but not easy. Time travel to the past is a no-no, or maybe a very, very big "maybe." Speculation on the possibility of time travel to the past includes worm holes, and quantum this and quantum that. Certainly time travel to the past is not easy like we see in so many time-travel novels. Now I'm wondering why we so often choose the past.
Bottom line: Time travel to the future possible but not easy. Time travel to the past is a no-no, or maybe a very, very big "maybe." Speculation on the possibility of time travel to the past includes worm holes, and quantum this and quantum that. Certainly time travel to the past is not easy like we see in so many time-travel novels. Now I'm wondering why we so often choose the past.
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June 6, 2019Kitap ünlü bir astrofizikçi tarafından yazılmış. Zamanda yolculuğu ve evrenin başlangıcını tartışıyor. Konuların herkesin anlayabileceği seviyede basit anlatıldığı söyleniyor ama bence en az orta seviye fizik bilgisi gerektiriyor. Kimya mühendisliği eğitimi almış bir kişi olarak ben ilk 150 sayfayı nispeten (%60-70 gibi) anlayabildim. Evrenin başlangıcı ile ilgili olan sonraki 40 sayfayı nerdeyse hiç anlamadım. Son bölüm olan Gelecekten Rapor kısmını çok kolay anladım ve sevdim. Özellikle Kopernik ilkesi ilgimi çekti. Bu ilkeye dayanılarak yapılan hesaplamaya göre homo sapiens daha en az 5100 yıl yaşarmış. (En çok da 8 milyon yıl)
Yıldız vererek değerlendiremedim bu kitabı. Bunu yapmaya yetkin olmadığımı düşündüğüm için.
Yıldız vererek değerlendiremedim bu kitabı. Bunu yapmaya yetkin olmadığımı düşündüğüm için.
September 3, 2019
I really enjoyed the fresh take on what can sometimes be a dull and dry subject. J. Richard Gott III serves up humor, down to earth (for astrophysics) explanations and examples of what makes up not only the theories of time travel but what has been proven over the most recent decades about such. From Wells' The Time Machine to Igor Dmitriyevich Novikov's self-consistency principles, we see how the idea of going back and forth through time has not only captured our imagination but has held strong for centuries.
Will it ever be a reality? Maybe it already is... :)
Will it ever be a reality? Maybe it already is... :)
July 10, 2024
Interesante y sencillo al principio, se va complicando hasta resultarme incomprensible en su parte central. Física demasiado complicada para mí y supongo que para la mayoría. Aún así, se puede leer. Pero llegar al final tiene un premio inesperado: el 5° capítulo abandona la física y entra en la especulación estadística o, mejor dicho, en la predicción de la duración probable de cosas o eventos tan variados como el gobierno de un partido político, el matrimonio de cada uno o la misma especie humana. Todo ello acompañado de una serie de conjeturas y reflexiones que me han parecido maravillosas. Por este último capítulo y las cosas que me ha hecho pensar le doy las cinco estrellas.
February 12, 2018
A good read, but...
This was a good read. I am not a physicist, but I was able to understand Gott's arguments well, so in that respect it was a good book, but, there were a number of formatting and spelling errors that made the reading a bit tedious in parts. If you're interested in the physics of time, then it's worth the money.
This was a good read. I am not a physicist, but I was able to understand Gott's arguments well, so in that respect it was a good book, but, there were a number of formatting and spelling errors that made the reading a bit tedious in parts. If you're interested in the physics of time, then it's worth the money.
August 15, 2018
I had a bit of a difficult time reading this book, as I had to concentrate way too much. Hey, I’m no Einstein. But I do love time travel, so I stuck with it to the end and was rewarded with lots of interesting bits how time travel may be possible, about the Big Bang, the creation of the universe and the Copernican principle. Science rocks!
December 31, 2018
A really nice quirky overview on the possibilities of time travel from a physicist's point of view and a little history of science thrown in as well. I found it engaging and fun and easy to read and wished it would have been more in some places and less in others. If you've read Kip Thorne's books on time travel (and black holes) and enjoyed them, you'll like this one, too.
Recommended.
Recommended.
November 27, 2018
Interesante libro donde de una manera lo más científica posible se intenta demostrar gracias a las teorías de Einstein que el viaje en el tiempo es posible. Tiene conceptos curiosos y realmente da que pensar en que el viaje en el tiempo es posible.
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