How to Build a Time Machine

by Paul C.W. Davies

With his unique knack for making cutting-edge theoretical science effortlessly accessible, world-renowned physicist Paul Davies now tackles an issue that has boggled minds for Is time travel possible? The answer, insists Davies, is definitely yes—once you iron out a few kinks in the space-time continuum. With tongue placed firmly in cheek, Davies explains the theoretical physics that make visiting the future and revisiting the past possible, then proceeds to lay out a four-stage process for assembling a time machine and making it work. Wildly inventive and theoretically sound, How to Build a Time Machine is creative science at its best—illuminating, entertaining, and thought provoking.

Genres: Science, Nonfiction, Physics, Time Travel, Philosophy, Popular Science, Mathematics

144 pages, Paperback

First published January 1, 2001

About the author

Paul Charles William Davies AM is a British-born physicist, writer and broadcaster, currently a professor at Arizona State University as well as the Director of BEYOND: Center for Fundamental Concepts in Science. He has held previous academic appointments at the University of Cambridge, University of London, University of Newcastle upon Tyne, University of Adelaide and Macquarie University. His research interests are in the fields of cosmology, quantum field theory, and astrobiology. He has proposed that a one-way trip to Mars could be a viable option.

In 2005, he took up the chair of the SETI: Post-Detection Science and Technology Taskgroup of the International Academy of Astronautics.

Reviews

[Ramy · Rating 4 out of 5]

قرأت هذا الكتاب لسببين
اولا لانه من تأليف عالم الفيزياء الشهير بول دايفيز و انا اثق فى اى كتاب عليه امضاء بول دايفيز من انه سيكون كتاب ممتع و مفيد فى الوقت ذاته
و ثانيا لاننى وجدت انه لا يوجد اى review عربى للكتاب
كلها تعليقات اجنبية و كأنه لا يوجد منا لعرب من هو مهتم بقرأة كتاب فيزيائى
http://i.dailymail.co.uk/i/pix/2010/0...
ناهيك طبعا..عن كم الاستظراف و السخرية الذى وجدته من الاصدقاء المصريين وا لعرب... بسبب عنوان الكتاب..السذج فقط هم من يحكمون على كتاب من عنوانه.. السذج فقط هم من يسمعوا عنوان الكتاب فيتبادر لمخيلتهم ان القارىء اثناء قراءته سيسارع لشراء ادوات قياس و خشب و مسامير و مخطط و رسم..و عدة و ادوات و يبدء فى البناء كلما قراء عدة صفحات من الكتاب نعم ..فهو كتاب عن كيف تبنى الة زمن ؟

الكتاب يكرر مرارا و تكرارا..على لسان المؤلف صعوبة بل استحالة السفر عبر الزمن على الاقل بإمكانات حضارتنا الحالية ...و لكنه ايضا يذكر بأن السفر عبر الفضاء "الطيران" كان ايضا حلم و يكاد يكون مستحيل و لكنه الان امر عادى جدا و من المسلمات...فلماذا الازدواجية ؟

الكتاب يمر و بخفة و ظرف و بساطة فى الشرح عبر عدة مفاهيم و نظريات فيزيائية هى تكاد تكون خيال علمى و لكنها حقائق فعلية...فقط اصحاب العقول وا لمخيلات الضيقة هم من يعتبرونها خيالات علمية

من موضوعات و عناوين الكتاب
المادة المضادة anti matter
الانفجار العظيم ..الانسحاق العظيم big bang big crunch
المتفردة singularity
مذنب شوماخر ليفى comet shoemaker-levy 9
سديم السرطان crab nubla
النظام و الفوضى order and chaos
وهذا ينقلنا لموضوع الانتروبى entropy
الاوتار الكونية cosmic strings
المفرق differentiator
EPR theory نظرية اينشتين بودولسكى روزن
einstien rosen bridge قنطرة اينشتين -روزن
حلقة اينشتين enstien ring
حقل هيجز Higgs field
نيوبيت الليثيوم lithium niobate
المعجل الهادرونى الكبير Large Hadron Collider
ألميون Muon
ميكانيكا الكم quantum mechanics
الكوارك quark
كوارك - جلوون بلازما Quark-Gluon Plasma QGP
التاكيون tachyon
تيراوات terawatt مليار وات
thought expriement تجربة ذهنية
vaccum الفراغ
الشق الدودى wormwhole
رغاوى فقاعات الزمكان spacetime foam

[Joanne G. · Rating 4 out of 5]

Contrary to the misleading title, this book does not contain any helpful schematics or step-by-step instructions to build a time machine. Once I recovered from my overwhelming disappointment, I enjoyed the simple (though deep) discussions of the different venues that could result in time travel.

As an avid science-fiction reader, I've nearly taken the idea of time travel for granted. The book cleared up some misconceptions. I hadn't realized that traveling backwards in time would be more problematic than traveling forward, but fiction is more forgiving than physics.

I'm knocking off a star simply because the book didn't help me build a time machine, so my dreams of traveling back in time to meet Charlotte Bronte or traveling forward to the future to see my great-great-great grandchildren will remain unrealized.

[Poncho González · Rating 3 out of 5]

Libro corto pero no necesariamente tan digerible donde se explica las posibilidades de viajar en el tiempo, hacia el futuro y pasado, tanto física como matemáticamente y sobre las paradojas que siempre resultan de proponer estos temas.

[Trevor · Rating 3 out of 5]

A very dear friend of mine bought this for me – and she was concerned that I might have read it already. I’ve read a couple of Davies’ books – but not this one. I can hardly remember what the others were called now – but they weren’t called How to Build a Time Machine of that I’m quite certain.

One of the others was also about time and also gave a rather involved discussion on why zapping off at the speed of light is even better than Oil of Olay if you are after younger looking skin. I’ve never understood this, never read an explanation that makes any sort of sense. I’ve now read Davies’ explanation in two books and I’m still none the wiser. I accept it happens – most of these guys have Physics degrees and tell me in all ponderous seriousness that it is so – all the same, it would be nice if just once someone would actually say what actually happens in a way that is both clear and comprehensible.

I once read an explanation that said imagine you are looking up from earth at a rocket that is speeding away from you at close to the speed of light. You also have to imagine that this is a special glass rocket, so you can see inside. There is a clock inside the rocket that measures time, but not your standard clock. Rather one that works by bouncing light rays off two parallel mirrors. Light travels at a fixed rate, so bouncing light off mirrors sounds as good a way to measure time as any other. The problem is that the person on the rocket sees the light bounce straight up and down – but you, standing on earth, see the light bouncing at an angle – a series of V shapes – which takes into account the velocity of the rocket. Light travelling in V shapes is going to take longer than light travelling straight up and down – so time will seem to go slower on the rocket ship than on earth. One is supposed to say, “It’s all relative” at this point – and so I will.

The problem is that it is relative – and so if you have the same clock ticking away beside you and I am on the rocket ship it will look, to me, as if your clock is making V shapes too. Both of us will think the other person’s clock is running slow. Davies points out that this is, in fact, the case, but then says the reason why the person in the rocket is ageing so much slower than the person left on earth has something to do with accelerating to light speed and then decelerating back down again. He doesn’t explain what it has to do with this or how it works – but he is not alone – no one ever seems to explain it. Like I said, I’ve always been left to take it on trust and to regret having never finished my physics degree.

I’m not going to tell you how to make a time machine – you can buy the book for that if you are interested. All I will say is that if you think you are going to be the next Dr Who or even The Master, you are probably going to be a bit disappointed.

Now, one of the reasons why we know time travel isn’t something that takes off in a big way in the future is because we don’t get visits from our descendents, or, at least, I haven’t had any yet. You would think that if time travel ever does become possible in the future and if the problem is purely one of technology, then when it is ‘invented’ that at least one of your many great, great (etc) grandkids would pop by – if only for some help with a history essay.

The fact they don’t and haven’t is a pretty good argument – pretty well conclusive - that we don’t ever invent time travel. However, this new atom smasher in Europe is proposing to change people’s minds on even this.

One of the things Davies says you might need to be able to go backwards in time is a wormhole and that would also require a way of inflating wormholes that are thought to exist at the quantum level. Our brand new atom smasher opening today in Europe might be just the thing for this and therefore flicking that particular switch might give all your future relatives a way to pop down and see you just in time for Christmas.

Look, I’ve very strong doubts that you are going to need to set any extra places for Christmas dinner – you can call me a sceptic if you like.

This is where I become completely confused. And I quote, “Time travel must not be confused with the equally fascinating (and equally speculative) topic of time reversal.” Hmm. So, why not? Well, Davies doesn’t really explain. How can you possibly go back in time without somehow reversing it? This is my big problem with time and time travel altogether.

You see, on the grandest scale time isn’t just something that tells you when your boiled egg will be runny or rock hard – it is a dimension of the universe and as such it is the thing that space expands into. (I recommend you pause and think about that for a second – so I’m going to say it again – time is that which space expands into).

I used to wonder what it would be like to stand at the edge of the universe – I don’t have to wonder anymore. I’m always already there. And so are you. The universe has been expanding for 13 billion years (give or take) and we are right now at the edge of that expansion. When you look around the night sky you see billions of stars (well, if you have a good enough telescope) and each one of those stars has one thing in common – they are all living in the past relative to you.

Given that the universe is expanding into time I can’t for the life of me work out what it would mean to go back in time. That would seem to mean – well, time reversal. And time reversal would seem to mean somehow squeezing the universe back to where it was. If you want to go back to 1950 the meaning of going back to 1950 is to have the universe the same size and shape as it was then. I don’t know how much energy that would take – to squeeze the universe back into 1950 – but I’m guessing that ‘a lot’ isn’t really going to cover it. And given most of us talk about the impossibility of ‘getting the toothpaste back into the tube’ it would seem somewhat ambitious to suddenly give up on the toothpaste and move on to squeezing the entire universe back to 1950.

People don’t like to hear that things are impossible – and that is one of the nice things about being a person, I guess. But just because Dr Who has his Tardis is no reason to suppose that in the future everyone gets to have one of their own. I feel like I’m spoiling the party, but until someone can explain more of the physics of time travel than is done here – or at least how going back in time isn’t the same as reversing time – then I’m going to have to assume this is all just so much wishful thinking, if not arrant nonsense.

All the same, Davies does make it clear that time travel – particularly backwards time travel – is problematic at best and this is probably the major value of his book.

[ياسر · Rating 3 out of 5]

«الكون ليس فقط أغرب مما فكرنا فيه، وإنما أغرب مما يمكن أن نفكر فيه»
- ج. ب. إس هالدين

تخيل أنك عُدت إلى الماضي لتقابل نفسك في سن الخمسة. ماذا ستُخبر نفسك حينها؟ والسؤال الأهم، هل هذا ممكن؟ ولو كان ممكنًا، فأي واحد من النسختين سيعبر عنك، أيهما أنت بجوهرك وكيانك؟
كلنا تمنينا السفر إلى الماضي، وتخيلنا أنفسنا أبطالًا يغيرون مجرى أحداث عظام.
وفي بدايات القرن العشرين جاءت النسبية لتغير مفهومنا عن الزمن وتأثره بعوامل عديدة كان يُظن سابقًا أنها لا تؤثر عليه من قريب أو بعيد. وأدى هذا لشلال من الأفكار حول السفر عبر الزمن، وأعاد الروح لتلك الفكرة المجنونة، التي أثارها من قبل كاتب الخيال العلمي الأشهر هربرت جورج ويلز في روايته المعروفة آلة الزمن قبل النسبية الخاصة بعدة أعوام.
وفي «كيف تبني آلة زمن؟» للفيزيائي البريطاني الشهير «بول ديفيز» يُعرض علينا اقتراحات لسُبل السفر عبر الزمن.
ويشرح إمكانية ذلك من خلال النسبية الخاصة من خلال شرح مبسط لنتائج النظرية، وتأثير الحركة على الزمن وكيف يمكن أن يتمدد الزمن بالسرعة. وأيضًا من خلال النسبية العامة وتأثير الجاذبية على سير الزمن.
ومن خلال دراسة مبسطة للثقوب السوداء والدودية وإمكانيات السفر عبر الزمن خلالها. ودمج لأفكار الخيال العلمي بأفكار علمية، من ذلك مثلا رواية العالم الشهير كارل ساجان «اتصال»، التي استخدم فيها الثقوب الدودية لهذا الغرض.
وفي أجمل وأطرف أجزاء الكتاب، يطرح ديفيز المتناقضات الفلسفية والمنطقية التي ربما تمنع السفر عبر الزمن، وبعض الحلول المقترحة لها. واحدة من تلك المعضلات هي متناقضة تغيير الماضي، فلو سافرت إلى الماضي وقتلتَ والدك، كيف ستكون موجودًا من الأساس لتقتل والدك!!
يقترح بعضهم حلا لتلك المعضلة وهي فكرة العوالم المتوازية.
و��يرها من المعضلات المثيرة للتفكير.
الكتاب شيق جدًا، ومبسط ومثير للخيال، وموضح لدور الخيال العلمي في تقدم العلوم ودور العلوم في تقدم الخيال العلمي.

[John · Rating 2 out of 5]

I was a bit disappointed by this monograph -- no, no, not because I was expecting a handy DiY manual but because the book didn't seem to me to do what I'd hoped for: explain (for the general reader) the physics that might permit time travel, in the broadest sense of that term, or at least the conveying of information across tracts of time.

Bits of this physics are already familiar to most of us: to get to the future faster than our one-second-per-second journey there, all you need is a spaceship that can travel fast enough that time dilation becomes significant or a handy, powerful gravitational field, such as that around a neutron star, for gravity-induced time dilation. In fact, we can achieve time dilation simply by moving around or going down a mine, even though the amount of time we gain on the future by doing so is minuscule (although not so small that physicists haven't been able to measure it, using highly accurate clocks, for long-distance plane trips). Sending energy/matter or information backward in time is very much more difficult, but not in theory impossible -- a careful choice of words there, because it may in fact be impossible for reasons that lie beyond our current state of theoretical knowledge.

In his first two chapters Davies discusses, respectively, the physics of going to the future and the past. Bearing in mind that much of this stuff was familiar to me, I got annoyed from time to time when Davies said, in effect, "The details needn't concern us," because the bits of physics that he was missing out were no more complicated than the ones he was including and because, without them, his explanations didn't seem to make proper sense. Once or twice, indeed, I found I was having difficulty understanding, as I followed a Davies explanation, stuff that I already knew, so that I had to put the book aside for a moment to remind myself of, so to speak, my brain's prior state!

The third chapter explains in slightly foggy fashion how in theory you might just possibly build a functional time machine if you happened to be an alien civilization whose science and technology were advanced immeasurably beyond our own; the method Davies describes in most detail involves the construction of an artificial wormhole. (I think, by the way, that he has his A and B back to front near the foot of page 90.) In the fourth and final chapter we have musings on the implications should time travel, in some meaningful sense, indeed be possible.

The illustrations (uncredited) are either bad sketches of the faces of the famous (Hawking, Wells, etc.) or graphs and diagrams that for the most part served, at least for this reader, to make the text less clear than it was.

I have Brian Clegg's 2011 book of the same title on my pile, and am hoping to get to it within the next few weeks; it'll be interesting to compare my reactions to the two treatments. As for this one, although I've enjoyed the other Davies books I've read -- and would regard his Other Worlds as something of a life-changer -- I'm almost embarrassed to say that I felt let down.

[عمر الحمادي · Rating 4 out of 5]

من يعتقد أن اللحظة الحاضرة هي نفس اللحظة عبر الكون كله فإنه مخطيء خطأً شديداً، ولا يجوز اعتقاد هذا الأمر بعد تحطيم نظرية النسبية لإينشتاين لنظرية نيوتن في المكان و الزمان، فالزمن نسبي وليس مطلق وكوني كما يردد الحس العام للناس، فالزمن يتمدد ويستطيل وينكمش، فلو فرضنا أنك في ذهبت ورجعت بالطائرة إلى اليابان وأنا مازلت في مكاني، فإن تدفق الزمن لكلانا هو نفس الشيء إلا أنه في الواقع سيكون أقل قليلاً بالنسبة لي، وهنا نتحدث عن الزمن الفيزيائي الذي يمكن قياسه بمنبهات لا عقول لها وتستطيع التقاط فروقات تصل إلى جزء من مئات الملايين من الثانية الواحدة.

لو انتقلنا إلى مثال أكبر وهو مثال التوأمين ، سام و سالي ، لو حلقت سالي في الفضاء في عام ٢٠٠١ بسرعة تقترب من سرعة الضوء إلى نجم تفصلنا عنه عشر سنوات ضوئية، وبقي سام في منزله لمراقبة سير سالي فسيلاحظ أنها تستغرق ٢٠ سنة بالتوقيت الأرضي، إلا أنه بالنسبة لسالي فإن رحلتها استغرقت ٣ سنوات فقط، فعند عودتها للأرض ستجد أن السنة هي ٢٠٢١، وهكذا يصبح سام أكبر من أخته ب١٧ عاما، إن بقاء سام في منزله جعله يأخذ الطريق الأطول لعام ٢٠٢١، لكن سالي بسبب سرعتها قصرت الزمن بين العامين الأرضيين ٢٠٠١ و٢٠٢١، فالسرعة هي أحد وسائل انحناء الزمن وتحدبه والوسيلة الأخرى هي الجاذبية التي تبطيء الزمن.

يبدو أنه لإنجاز آلة الزمن يعلق الفيزيائيون الآمال على الشقوق الدودية في الفضاء والتي إن ثبت وجودها فإنه يُفترض أنها تربط بين الأكوان وتتغير مواقعها باستمرار، ولقد أبدى ستيفن هوكنغ شكوكه حول العملية الإعلامية حول تحول الشقوق الدودية إلى آلة زمن ، و لتكون هذه الشقوق قابلة للاجتياز يجب على المسافر أن يمتلك القابلية للعبور والخروج سليماً قبل أن ينغلق الشق على نفسه الذي من الممكن أن ينهار في حال مرور المادة المألوفة مثل الماء والماس والهيدروجين الخ الخ، يقول مبدأ اللايقين لهايزنبرج بأن الكميات الفيزيائية تتموج أو تتردد في الفراغ عشوائيا، وكلما صغر المقياس كلما زاد عدم اليقين مما يعني أن قيمة الطاقة غير قابلة للتنبؤ، والطاقة المتطلبة لإحناء الفضاء إلى رغاوى معقدة ينطبق عليه مبدأ هايزنبرج.

[Sybrina Parker · Rating 3 out of 5]

Short fun read
I wouldn’t recommend to everybody but it was interesting and educational in a way that was understandable.

[Leanne · Rating 5 out of 5]

I want to nominate this book for the Nobel Prize in literature ~~in the category of clearest explanation of a difficult topic. This book is truly excellent on the fundamental theory behind time travel's biggest challenges. Paradoxes for example. How many books does a person have to read before they understand light cones and what this has to do with causality? Well, I can tell you, they have to read a lot. This one was the first that actually made me think I understood the concept (but in retrospect, now I am not so sure about that).

Despite being short, this is not a book for slackers. Obviously, future time travel is for losers --and I skipped those parts of the book--and went straight to the engineering chapters. Davies has a four part method for building a past-travel -capable machine. Choosing to use wormholes (~~~~~~yawn!) he has his worm hole factories growing these worm holes from planck scale babies; feeding them with exotic matter in the inflater to grow them into something big enough to use for human time travel. [Remember, we are aiming for the past]. He seems to think this is the best option for creating past-capable time travel. I have my doubts about any plan that proposes to engineer in planck scale sizes. We are centuries away from even seeing that small much less engineering in those scales. Plus, do we really want to travel in worm holes? Now, time spirals, in my humble opinion is much more appealing. Davies toyed with Godel's idea of a rotating universe but backed away from that--citing a lack of evidence (~~~yawn!). That was a mistake, in my opinion. Not even his first mistake either. How much harder can it be to set the universe into rotation compared to the tedious and impossibly challenging method he outlines for a wormhole factory?????

Despite my complaints about his vision for building a workable machine, the writing is charming and fun. He made me laugh. And, the penguin edition is also very futuristic--even highlighting the text where one is supposed to pay special attention, which is everything!

A lucid romp says the blurb. Indeed! So, now onward to find a good book on Kurt Friedrich Gödel!

[Filip · Rating 3 out of 5]

Time traveling is most often trope of sci-fi films and books and some scientists are actually thinking about implications of time travel and is it possible or not. Paul Davies wrote this book to answer as simply as possible about time traveling and I've got to say as much that this is simple I still didn't understand many of the things he wrote. I must be very stupid :-D but all in all I don't think this is a bad book but it is not for everybody and I recommend it to all people that really love time travel and physics.

[Nick Van Lente · Rating 4 out of 5]

Cool book! Makes particle physics approachable!

[كتابك التالي · Rating 4 out of 5]

مراجعتي على يوتيوب https://youtu.be/siwfNlhHwCU

[Niklaus · Rating 5 out of 5]

Il titolo del saggio (perché non è né SF né un "manuale") deve essere preso letteralmente: avendo a disposizione energie e risorse oggi non disponibili e basandosi solo sulle conoscenze della fisica teorica disponibili al momento della stesura, sarebbe possibile, e se si come, costruire una macchina del tempo?
Il merito di Paul Davies, astrofisico rinomato e divulgatore per passione, è stato quello di creare un libro solido, conciso, aperto a diverse possibilità, anche quelle più estreme (come la stabilizzazione di un wormhole) ma sempre nel rispetto del scientificamente plausibile (anche se oggi non possibile).
Il libro non è recente (2001) quindi alcune di queste nozioni (poche invero) sono state superate dal progredire delle conoscenze (il bosone di Higgs, la prova dell'esistenza delle onde gravitazionali e con esse la realtà dei buchi neri, …) ma non ho mai avuto la percezione di una lettura datata.
Altra nota di merito le dimensioni contenute e l'agilità tutta anglosassone di scrivere in modo semplice (relativamente parlando, in fondo è un libro di fisica estrema) ma non banale. L'autore ti porta per mano prima nei concetti base della relatività e fisica quantistica per spiegare la rivoluzione di Einstein con la negazione del tempo e la sua sostituzione con lo spazio-tempo, e poi ti spiega come, in teoria, potrebbe essere possibile viaggiare nel tempo.

Le 5 stelle sono date anche in contrapposizione ad un altro libro letto recentemente (quello di Rovelli sul tempo) in cui, al netto essere entrambi fisici di altissimo livello, erano più le pagine farcite di disquisizioni filosofiche e citazioni (dai filosofi greci ai Veda), che annacquavano e logorroicizzavano la parte di scienza. Purtroppo è un problema comune a molti scienziati italiani formatisi prima degli anni '80 e che vengono da background ginnasiale (e di inconsci influssi crociani); un mix che sembra troncare sul nascere ogni possibilità di divulgazione concisa, senza divagazioni e agile.
Di sicuro rimarranno delusi coloro che si aspettavano un vero manuale sul costruire prototipi tipo la macchina del tempo di HG Wells, la cabina telefonica del Doctor Who o la DeLorean di Ritorno al Futuro. A meno di scoprire come creare un wornhole (il traduttore qui ha usato "cunicolo di tarlo" ma sono restio a tradurre concetti) da laboratorio o di avventurarsi in zone "inospitali" come i buchi neri (Interstellar) o incappare in una corda cosmica (nozione che ho scoperto dal libro) tali avventure rimarranno solo nelle formule dei fisici teorici (possibili ma non fattibili).
Sempre che il concetto di "protezione della cronologia" non finisca per essere un principio come il secondo principio della termodinamica per cui il viaggiare nel tempo sia un tabù cosmico insieme a concetti come il moto perpetuo e le singolarità nude.
Comunque sia, questo è un libro che rileggerò per sedimentare alcuni concetti e per vedere come questi si sono evoluti negli ultimi 20 anni.

[Abd Rsh · Rating 5 out of 5]

شرح الدكتور بول ديفيز في هذا الكتاب عدد كبير من المبادئ والمفاهيم مبتدئاً بالمفاهيم الأساسية عن الفيزياء الكمية والنظرية النسبية وعدد كبير من الأفكار الفيزيائية لكبار العلماء.
برأيي الكتاب مفيد جداً و يحوي الكثير من المعلومات القيمة والتي لن يستطيع معرفتها الشخص العادي فقط من متابعته للمقالات العلمية ..
انصح كل شخص يحب الاطلاع على هذا الباب الواسع من العلم بأن يقرأ هذا الكتاب بتمعن كبير وبتركيز كبير وان لايتعجل في قرائته.
قام الكاتب بربط الأفكار التي طرحها بشكل ممتاز لدرجة أنك قد تحتاج أن تعود للخلف عدّة صفحات لتراجع فكرة معينة وردت واعيد استعمالها ضمن فكرة أخرى بنيت عليه��.
عند قرائتك لأفكار معينة قد تضطر لقرائتها عدة مرات حتى تستطيع أن تفهمهما أو أن تقربها لطريقة تفكير معينة بحيث تستطيع أن تفهمها ولو بشكل جزئي، وقد يمر عليك عدد قليل جداً من الأفكار التي ستجد أنها غير مشروحة بالشكل الكافي وقد لا تستطيع فهمها.
وفي النهاية أعتقد ان هدف الكاتب من هذا الكتاب هو نشر الأفكار الخاصة بمجال الفيزياء الكمية والنظرية النسبية ضمن المجتمع أو على أقل تقدير أراد تعريف القارء على هذه الأفكار بشكل مبسط وبعيد عن التعقيد الخاص بالعلاقات الرياضية والعمليات الحسابية، وأظن أيضاً أن الكاتب أراد أن يعرف القارء على عدد من أسماء كبار العلماء المختصين في هذا المجال واللذين كان لهم دور كبير فيه واللذين لم يسبق لنا ان سمعنا بهم وذلك نظراً لأن معظم المقالات المنتشرة تذكر فقط دور العالم أينشتاين في هذا المجال وتهمل لحد كبير الدور الكبير للعلماء اللذين خلفوه واللذين تابعو العمل في هذا المجال ومنهم:

-كارل شوارزتشيلد: وهو العالم اللذي قدم أول حل صحيح للنظرية النسبية وناقشه مع أينشتاين حيث وافقه الاخير على هذا الحل.
-كيب ستيفن ثورن
-لودفيج فلام
-ماكس بلانك
-ناثان روزن
-ستيفن هوكينغ
-هندريك كازيمير

وحتى كاتب هذا الكتاب بول ديفيز له عدد كبير من الانجازات في هذا المجال.
يقول لك هذا الكتاب في معناه أن المبادئ الأساسية في السفر عبر الزمن موجودة وبعضها قد تم التحقق منه وان العلماء في عصرنا هذا يستطيعون بشكل نظري أن يبنوا ألة الزمن ولكن المشكلة هي بتأمين متطلباتها العملية والتي هي حالياً بعيدة جداً عن القدرة البشرية.
أخيراً أود أن أطرح أسماء أخرى للكاتب قد تناسبه بشكل أفضل مثل: الزمن وما وصل إليه العلم أو إنجازات البشرية في الانتقال عبر الزمن أو ألة الزمن، مبادئها ومستلزماتها

[briz · Rating 3 out of 5]

Fun, short. Post-Einstein physics is so freaky. The tldr: going FORWARD time is easy (just travel as close to the speed of light as possible). Going backward is tricky, but also - thanks to the multiverse - basically possible.

Related reads:
- Seven brief lessons in physics, Carlo Rovelli
- Astrophysics for people in a hurry, Neil DeGrasse Tyson
- The accidental universe, Alan Lightman
- Why is there anything?, Matthew Rave
-
McCoy: The Provenance Of Shadows (Star Trek: Crucible, #1), David R. George III

[Hugh Chatfield]

It is kind of interesting to find out that although we don't have the technologies to carry this out - we can think of, and show how to construct such a device. There is nothing in Physics that says this can't be done.

I'd be quite happy to only discover how to send and detect signals going backward in time. Maxwell's equations show two solutions when solved. One is the forward in time e/m that we are all familiar with and make use of. The other is a backward in time e/m wave. Typically this solution is discarded as "imaginary". I think it was Feynman who first wondered - what if it is not imaginary? - and is the basis for at least one post graduate degree, and a Chapter in "Schrodingers Kittens". Figuring out how to detect (right now) a signal sent out in the future would be a handy device.

[AbdElsatar · Rating 3 out of 5]

الكتاب ده مش دليل عملي لبناء آلة زمن زي ما الاسم ممكن يوحي، لكنه بيشرح النظريات العلمية اللي ممكن تخلي السفر عبر الزمن حقيقة. بول ديفيز نجح إنه يبسط أفكار معقدة جداً بطريقة سهلة.
بيقول الكاتب ان السفر للماضي نظريا ممكن عن طريق الثقوب الدودية ولكن تظل مفارقة الجد مشكلة كبيرة جدا واللي بتنص على ان ماذا سيحدث إذا سافر شخص ما إلى الماضي وقتل جده قبل أن ينجب أباه؟
إذا حدث ذلك، فكيف سيولد هذا الشخص أصلاً ليقوم برحلة إلى الماضي ويقتل جده؟ هذا التناقض الظاهري هو جوهر مفارقة الجد.
والكاتب بيوضح كمان ان السفر للمستقبل ممكن من خلال السرعات العالية جدا او من خلال الجاذبية القوية
الكتاب ممتع جداً وبيفتح العقل لأفكار جديدة. حتى لو مش هنقدر نبني آلة زمن دلوقتي، بس فهم النظريات دي بيخلينا نفهم الكون أحسن.

[Luke · Rating 5 out of 5]

Wonderfully brief, Davies turns in an easily-finished primer on the mechanics behind time travel, and the implications of taking such a trip - assuming you're not spaghettified in the process.

This is a deep subject, and while sci-fi is constantly referenced, the author manages to convey some of the major points with a subtlety that aids the physics clod (such as myself) who can find Hawking's books a little intimidating.

Davies has produced something that makes the gee gosh parts of time and space result accessible, from Einstein on up. It'll start a fire.

[Martin · Rating 4 out of 5]

Briefly encompasses everything physics has to say on time travel, paradoxes and different ways time travel could potentially, THEORETICALLY be accomplished. It doesn't however provide actual plans on how to build your own. .. On second thought, it does, but you'll need stuff you can't buy at your local store.

[Raphael · Rating 5 out of 5]

This book is really interesting. At times can be confusing, but is mostly really enjoyable. I have always dreamed of time travel, and this book was really good for me to read. It helped me understand a lot of parts of my theory. I would suggest this book if you really want to get sucked into an amazing philosophic idea.

[Lily · Rating 3 out of 5]

Surprisingly brief - it was all well and good until Davies started blabbering about the quantum multiverse, inflators and negative energy..then I got kind of confused. But it was a very curious read, (I'll recommend this to anyone who wants to get a clean-cut summary on the subject.)

[Pedro · Rating 4 out of 5]

penso nunca ter conseguido imaginar que isto seria possível em termos físicos!
apesar deste livro ser de divulgação, mesmo para o leitor menos preparado dara uma boa ideia sobre viagens no tempo e a(possível) física por de trás.

[Danger_danger · Rating 1 out of 5]

Traduction française non relue, beaucoup de fautes...

[عصام · Rating 4 out of 5]

استعراض شيق لكل نظريات السفر عبر الزمن التي ظهرت حتى تاريخ الكتابة.

الترجمة سيئة، لكنها اهتمت جيدًا بشرح المصطلحات العلمية الدقيقة.

[Yassir · Rating 4 out of 5]

الكتاب يركز على الجانب النظري اكثر من العملي

[Alan · Rating 4 out of 5]

Let's get this out of the way first: time travel like you see in the movies will probably never become a thing. Physics simply doesn't make things like a flux capacitor plausible. Therefore, you ought to know that this book won't help you or anyone else build a working time machine. It's simply not possible with today's technology, and it might never be possible.

That is not to say the book is a waste or doesn't deliver on its promises, because the third chapter does get really deep into the details of a hypothetical model for a time machine that could jive with physics. It's not as easy as you might think: if you don't have a giant spinning cylinder that's as long as infinity, then you're best bet is to create a microscopic wormhole by conjigguring with quantum science (don't even ask me how, quantum mechanics is my biggest blind-spot). But then you'd have to solve bigger problems, such as how to keep it open for longer than a trillionth of a second or so. And you'd have to enlarge it, probably with matter that gives off antigravity, which may or may not exist. Then you'd have to pump it full of negative energy, which can either be found in black holes, or generated with some crazy contraption involving mirrors and lasers the size of the solar system. If you manage all that, then congratulations, you made a singularity. There's a lot more details to it--I think part of the process involved hurling a bunch of nukes at it. You know what you can do with your wormhole then? You can either wait for so-many years to use it, so you can go back in time to the point the thing was made. Or you can drag the wormhole to a stellar body and use time dilation to go back in time, potentially beyond the time machine's invention. Maybe.

If it sounds too incredible to ever happen, then you can see the real value of the book: it underscores just how complex space and time are interconnected, and it lays out the reasons why time travel in sci-fi is so implausible. The book is a pretty short, breezy, high-level examination of basic relativity--if you know about it going in, it's nothing new. Newcomers might struggle a bit to grasp these concepts, but I think Davies does a good job of relaying the information in simple, laymen's terms. There are more advanced theories and concepts that lie beyond the scope of the book (such as String Theory, M Theory, Multiverse Theory), but I'm glad it doesn't over-complicate things.

For an aspiring sci-fi writer like myself, this book is a pretty brisk and enlightening read--a firm reminder of how scientific theory actually works and how unlikely it is that we'll ever have a working time machine. Casual and curious readers ought to give it a try--it might be something you know about already, but designing a plausible time machine is an interesting thought experiment.

[Mohammad Al Refaei · Rating 3 out of 5]

لقد جمح خيال البشرية كثيراً، حلم أجدادنا بالطيران وبالخلود وبالوصول إلى القمر، حلموا بدواءً يشفي من كل داء، وحلموا بامتلاك القوى الخارقة وبالكائنات الفضائية؛ كل هذا مشوقٌ ويعد مادةً دسمةً للخيال العلمي، لكن، هناك أمرٌ آخر تكاد تكون له حصة الأسد من خيال الكتاب ألا وهو "آلة الزمن"، وروعة هذا الكتاب أنها تعلمك كيف ستبنيها، إن صح استعمال هذه العبارة.
أولاً، الكتاب ليس كتاباً خيالياً بل علمياً، وثانياً، لا تتوقع أن تجمع المسامير والأنابيب والمحركات بعد قراءة هذا الكتاب لبناء آلة زمن فهذا كتابٌ علمي كما أخبرتك؛ حقيقةً، فالكاتب يقدم لنا شرحاً علمياً للسفر عبر الزمن عن طريق الثقوب الدودية والطاقة السلبية، ويشرح لنا كل ذلك بالتفصيل: كيف تنشأ الثقب الدودي وكيف تكبره ليتسع لنقل الأشخاص وكيف تنشأ الطاقة السلبية وما هي العقبات التي تعترضك في كل مرحلة (وقبل هذا يشرح لنا النسبية التي لا يمكن بدونها السفر عبر الزمن).

وطبعاً، يتعرض الكاتب للسفر بالطريقين: إلى الماضي (الذي يعاني الكثير من المشاكل والتناقضات، فتخيل أن يسافر شخصٌ للماضي ليقتل أمه قبل أن تنجبه وبالتالي لن يكون موجوداً للسفر إلى الماضي لقتل أمه!) والسفر إلى المستقبل ، ويحاول طرح أجوبة عن المشاكل التي تعترض كليهما.
تستطيع أن تفهم من الكاتب أن السفر في الزمن صعب للغاية وتعترضه حواجز عملية ونظرية.
موضوع الكتاب شيق لكن قد لا يهم قسماً من الناس ولذلك قد يبدو مملاً أو صعباً بالنسبة لهم، لكن، إن كنت تحب الإطلاع على الموضوع، فهذا الكتاب جيد، فضلاً أنه يحوي ملحقاً كبيراً يشرح فيه المفاهيم الفيزيائية الصعبة ويزودك بمجموعة من الكتب العلمية والخيالية لتثري عن طريقها معرفتك.
أنصح به.

[Ahmad's Bookmovels · Rating 3 out of 5]

أولا أسلوب بول ديفيز أسلوب مبسط ورائع، فلن يتطلب الأمر معرفة كبرى بأمور الرياضة والفيزياء حتى تستوعب الكتاب.. أي أنه أسلوب علمي خالطه التبسيط.. فلم يسلك الكاتب أسلوبا علميا بحتًا لأن كتابه لجميع المهتمين بالفزياء الفلكية وليس للمختصين فقط.
أما عن محتوى الكتاب: فهو جيد لمن يمتلك معرفة مسبقة أو أولية بنظريات السفر عبر الزمن، غير واضح لمن يفتقر إلى هذه المعرفة.. إلا أنني أرى هذا الكتاب فرصة جيدة لدخولك عالم الفيزياء الفلكية ومداعبة خيالك بطريقة علمية لطيفة! لذا لا تؤجل قراءته!
فمحتوى الكتاب جيد جدًا وبه كم كبير من المعلومات.. بالإضافة إلى هذا، فهو مليء بجدل علمي رصين، خاصة أن الكاتب قام بعرض النظريات التي تقف مع الارتحال الزمني وتلك التي تراه ضربًا من الخيال.. وهو أمر ممتع ويخفف من الملل، وسيساعدك أيضًا على معرفة الأمور بطريقة أشمل.. فتلك النظريات قد زادت ثراء الكتاب بطريقة شيقة.
لكن ما لم يعجبني في الكتاب هو أنه لم يُضف إلى موضوع السفر عبر الزمن شيئا جديدًا.. لأن بول ديفيز عرض ما تم التوصل إليه ويترك للقارئ مهمة البحث والوصول إلى جواب.. لكن بوجهٍ عام، هو كتاب جيد.
أما عن منطقية موضوع الكتاب، فدعنا نتفق على أنه حتى لو كان الارتحال في الزمن مستحيلًا -على الأقل اليوم- فإن هذا لا يعني أننا يمكننا تجاهل تطبيقاته..

يمكنك قراءة المزيد من مراجعتي للكتاب وتلخيصه من هنا:


link: https://bookmovels.com/كيف-تبني-آلة-زمن-لبول-ديفيز/

[Jim Razinha · Rating 5 out of 5]

A couple of months ago I found Davies’ The Last Three Minutes in a D.C. bookstore. I’d read Steven Weinberg’s The First Three Minutes years ago and Davies’ book intrigued me. Looking for it, I found this.

I know of Davies, but haven’t read any of his work before. I need to fix that because this is very readable. Davies has a conversational approach to conveying a complex subject. He doesn’t get bogged down in the math, but he does given references to the technical papers he draws from. (He also refs other books and even fiction!)

In the 1960s physicists and mathematicians began studying the properties of spinning black holes. These bulge around the waist in the same manner as rotating planets because of centrifugal force. Now centrifugal force acts to oppose gravity.

That’s bound to get someone claiming “the physicist doesn’t know that centrifugal force is fictitious!”, but he’s not wrong as the frame of reference is the spinning black hole.

[Sparrow .]

Gravity bends time. So does acceleration. The manifold mathematical implications of the bafflingly simple formula e= mc¬¬2 are brain-defying.

I knew this was a populist physics text, but only towards the end did I discover – from reading the back cover – that Paul Davies is a major scientist. The way gifted poets dream of writing an epic poem where every word begins with the letter “p”, big-deal physicists imagine building rocket ships that hurtle through time! “Physicists do indeed think of all time as equally existent – making up an extended ’timescape,’” Davies instructs. How to Build a Time Machine – which, though published in 2001, has no subtitle (which is impressive) – contains clarifying full-page graphics like the one captioned: “On a spherical surface such as the earth it is possible to draw a triangle with three right angles.” And by gum, you see that triangle!