einstein theory of time travel in hindi

क्या है स्टीफन हॉकिंग द्वारा समय यात्रा का सिद्धांत?

क्या समय में भूत में और भविष्य में यात्रा करना संभव है.

Stephan Hawking and Einstein Time Travel Theory In Hindi –   यानि की वर्तमान समय के आगे और पीछे के समय में जाकर के यात्रा करना, यह सुनने में तो अच्छा लगता है पर जब इसे गहराई से सोचा जाता है तो हमारा दिमाग चकरा जाता है। समय यात्रा फिल्मों में हमें काफी मजेदार लगती है पर इसके सिद्धांत और पहलु हमें रहस्य में डाल देते हैं।

वैज्ञानिक द्रस्टी से देखा जाए तो समय यात्रा संभव है अगर देखा जाए तो हम सभी समय में यात्रा कर रहे हैं हम सभी भूतकाल से निकल कर वर्तमान में होते हुए लगातार भविष्य की ओर बढ़ते चले जा रहे हैं और इसी को ही समय यात्रा कहते हैं और हमारी समय में यात्रा की दर 1 घंटे प्रति घंटे की दर से है।

यानी की हमें भविष्य में 1 घंटा आगे जाने के लिए 1 घंटे का ही समय अंतराल लगेगा ! लेकिन क्या Time Travel की दर को एक घंटे प्रति घंटे की दर से भी ज्यादा तेज किया जा सकता है?

तो क्या हम छोटे से समय अंतराल में ही भविष्य में आगे जा सकते हैं? जवाब है हाँ, हम छोटे से समय अंतराल में हजारों साल का सफर तय कर सकते हैं ।

विषय - सूची

आइंस्टीन का सापेक्षतावाद का सिध्दांत

जब अल्बर्ट आइंस्टीन ने थ्योरी ऑफ़ रिलेटिविटी यानी सापेक्षतावाद का सिध्दांत प्रकाशित किया तो उसी सिध्दांत के आधार पर टाइम ट्रेवल की कल्पना की जाने लगी।

आइंस्टीन के थ्योरी ऑफ़ रिलेटिविटी सिध्दांत के प्रकाशित होने से पहले लोगों में केवल एक ही अवधारणा थी कि ब्रह्माण्ड में समय की गति हर जगह वही है जो पृथ्वी पर होती है ।

उनका मानना था की समय जिस रफ़्तार से पृथ्वी पर गुजर रहा है उसी प्रकार ब्रह्माण्ड में दूर कही किसी दूसरे ग्रह पर भी समय इसी रफ़्तार से गुजर रहा होगा ! लेकिन आइंस्टीन ने लोगों की इस अवधारणा को गलत साबित कर समय की  एक अलग परिभाषा दी।

स्पेसटाइम क्या है? What is SpaceTime 

(the time travel theory) .

अल्बर्ट आइंस्टीन ने बताया कि समय और अंतरिक्ष एक दूसरे से जुड़े हुए हैं ! जिसे SpaceTime कहते हैं ! समय एक 4th डायमेंशन यानी चौथा आयाम है और समय की गति को धीमा या तेज किया जा सकता है.

ब्रह्माण्ड में समय एक नदी की तरह चल रहा है जिस तरह नदी में कहीं पर पानी की रफ़्तार तेज होती है तो कहीं धीमी उसी प्रकार ब्रह्माण्ड में समय अलग अलग जगहों पर अलग अलग गति से चल रहा है !

आइंस्टीन के द्वारा थ्योरी ऑफ़ रिलेटिविटी सिध्दांत में दिए स्पेस टाइम की समीकरण से ही समय यात्रा सम्भव है। आइंस्टीन की स्पेस टाइम की समीकरण के अनुसार अगर कोई वस्तु जितनी तेज चलेगी तो उसके लिए समय धीमा हो जाएगा और उस वस्तु की गति जितनी बढ़ती जायेगी तो उसके लिए समय उतना ही धीमा होता चला जाएगा।

यह भी जानें –  समय यात्रा की 10 सबसे रहस्यमयी सच्ची घटनाएं, देखें वीडियो

प्रकाश की रफ्तार पर ही समय यात्रा संभव है –  time travel theory .

जब आप तेज रफ़्तार से चलने वाली रेलगाड़ी या हवाई जहाज में सफर करते हो तो आपके लिए समय बाहरी दुनिया के अपेक्षा धीमा हो जाएगा और जब आप अपनी यात्रा के बाद उस ट्रैन या हवाई जहाज से बाहर निकलोगे तो आप भविष्य में पहुँच चुके होंगे।

हालांकि इतनी काम रफ़्तार से चलने की वजह से आप भविष्य में एक सेकंड के करोड़वें हिस्से जितना आगे पहुँच पाओगे।

समय का यह अंतर बहुत ही मामूली है समय के इस अंतर को महसूस करने के लिए आपकी रफ़्तार प्रकाश की रफ़्तार के बराबर या 95% तक होनी चाहिए।

टाइम ट्रैवल(Time Travel) और रेलेव ट्रैक

बिगबैंग सिध्दांत और ब्लैक होल जैसी अवधारणाओं को समझाने वाले स्टीफन हौकिंग ने टाइम ट्रेवल के लिए एक ऐसे रेलवे ट्रैक की कल्पना की जो पृथ्वी के चारों ओर बना हो और उस ट्रैक पर चलने वाली ट्रैन की स्पीड प्रकाश की गति के बराबर हो।

जब वो ट्रैन पृथ्वी के चरों ओर बने ट्रैक पर प्रकाश की गति से चलेगी तो ट्रैन में बैठे यात्रियों के लिए समय धीमा हो जाएगा इतना धीमा कि उनकी तुलना में पृथ्वी पर गुजरता हुआ जीवन तेजी से नजर आएगा इतना तेज कि ट्रैन के पल यहां के महीनों में बदल जाएंगे।

हालांकि ट्रैन में बैठे यात्रियों को ट्रैन के अंदर का समय सामान्य की तरह ही महसूस होगा लेकिन बाहरी दुनिया की तुलना में ट्रैन के अंदर का समय बहुत धीमा हो चूका होगा।

जब ट्रैन में बैठे यात्रियों के हिसाब से ट्रैन एक हफ्ते के बाद रुकेगी तो यात्रियों के एक हफ्ते के सफर में पृथ्वी पर 65 साल गुजर जाएंगे और वो यात्री खुद को भविष्य में पाएंगे और उन यात्रियों के लड़के उनसे ज्यादा बूढ़े हो चुके होंगे।

क्या भविष्य में ही समय यात्रा संभव है? – The Time Travel Theory and Future 

आइंस्टीन की स्पेस टाइम समीकरण के अनुसार केवल भविष्य में ही समय यात्रा संभव है यानी एक बार भविष्य में पहुँच गए तो पीछे वापस नहीं आ सकते ! मतलब One way Ticket to the Future.

अब यहां पर एक सवाल सामने आता है कि क्या प्रकाश की गति से चलने वाली ट्रैन बना पाना संभव है?  हमारी अभी की तकनीक के हिसाब से जवाब शायद निराशा जनक हो सकता है।

अभी ऐसी ट्रैन बनाना संभव नहीं है क्योंकि आइंस्टीन की थ्योरी ऑफ़ रिलेटिविटी के अनुसार अगर किसी वस्तु की स्पीड बढ़ती जायेगी तो उसका द्रव्यमान भी बढ़ता जाएगा।

प्रकाश की गति के लिए चाहिए अंनत ऊर्जा – The Infinite Energy For Time Travel

मान लीजिये कि हमने ऐसी ट्रैन बना ली जो प्रकाश की गति से चल सकती है जब ये ट्रैन प्रकाश की गति से चलेगी तो इसका द्रव्यमान अनंत हो जाएगा । और आइंस्टीन के द्वारा दिए गए समीकरण E = mc^2 से अनंत द्रव्यमान वाली ट्रैन को चलाने के लिए अनंत ऊर्जा की ही जरुरत पड़ेगी।

यह भी जानें –  जानिए क्या है स्ट्रिंग थ्योरी ? क्या कहता है विज्ञान – String Theory Explained in Hindi

इतनी ऊर्जा तो हमारी पूरी गैलेक्सी में भी नहीं है अगर हम पूरे ब्रह्माण्ड की ऊर्जा को उस ट्रैन में भर दें तब शायद वो ट्रैन प्रकाश की गति से चले।

अगर हम उस ट्रैन को प्रकाश की गति के 90 या 95% तक चलाएं तब शायद उस ट्रैन को इतनी स्पीड पर चलाने में हमारी सम्पूर्ण गैलेक्सी की ऊर्जा चाहिए।

अब यहां पर एक सवाल सामने आता है की प्रकाश की गति से चलने वाली वाली ट्रैन बनाना संभव नहीं है तो क्या हमारी समय यात्रा ( time travel ) की कल्पना यहीं ख़त्म हो जाती है। मेरा मानना है नहीं, इस सिध्दांत के अलावा भी कई और सिध्दांत हैं जिनके द्वारा समय यात्रा सम्भव है।

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यह संभावित आर्टिकल हमने techandmyths.com से लिया है, समय यात्रा के इस सिद्धांत (Time Travel Theory)  पर गहराई पर विचार करें तो आप लोगों को भी लगेगा कि विज्ञान वास्तव में जैसा दिखता है वैसा है नहीं।  पर फिर भी आप अपने मन की कल्पना को दौड़ा सकते हैं और समय में एक काल्पिनक यात्रा तो कर ही सकते हैं।

विज्ञान से जुड़ी किताबें पाने के लिए आप इस लिंक पर जरूर जायें , यहाँ आपको विज्ञान के कई विषयों पर डिजिटल किताबें आसानी से मिल जायेंगी।

Shivam Sharma

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Theory of Relativity Hindi/सापेक्षता का सिद्धांत उदाहरण

Albert Einstein जिसको सुनते ही हमें E=mc², theory of relativity in hindi और spacetime जैसे सिद्धांत याद आ जाते हैं। Einstein एक ऐसे व्यक्ति थे, जो सदियों में कभी-कभी जन्म लेते हैं। Albert ने अपने सिद्धांतों के द्वारा दुनिया में तहलका मचा दिया था। यह ही वो व्यक्ति थे, जिन्होंने newton को गलत साबित करते हुए gravitation पर नई theory दी थी। अक्सर पहले वैज्ञानिक experiments करते हैं और उसके आधार पर theory लिखते हैं। लेकिन Albert Einstein एक ऐसे व्यक्ति थे जो अपनी कल्पना में सोचते थे। फिर उसके बाद उस theory के आधार पर experiments को अंजाम देते। आज हम आपको इनके ऐसे ही एक सिद्धांत के बारे में बताऊँगा जो आपकी सोच को चुनौती देगा। आज हम बात करेंगे थ्योरी ऑफ रिलेटिविटी / Theory of relativity in Hindi ।

Table of Contents

Albert einstein ke siddhant

Theory of relativity की शुरुआत: इस ब्रहमांड के कण-कण में एक चीज है जो constant है वो है गति। ब्रहमांड के कण-कण में गति ब्रहमांड के जन्म से शुरू हो गई थी। लेकिन पृथ्वी पर मौजूद लोगों ने गति को भौतिक तरीके से करीब 300 साल पहले पहचाना। जब दुनिया ने गति के नियमों को एक नए नाम से पहचाना जो था Sir Isaac Newton ।

Newton के गति के नियमों ने इस दुनिया को समझने का एक नया तरीका दिखाया। Newton ने बताया कि कोई भी वस्तु स्थिर या गति की अवस्था में तब तक रह सकती है। जब तक उस वस्तु पर कोई बाहरी बल न लगाया जाए। किसी भी वस्तु पर लगाया गया बल उसकी गति को बढ़ा भी सकता है और घटा भी सकता है। लोगों ने गति को तो समझा लेकिन अब एक नई समस्या सामने आई कि इस गति का निर्धारण कैसे किया जाए यानी इस गति को कैसे मापा जाए।

न्यूटन के गति नियम

जैसे मान लो कि आप railway platform पर बैठे हो और आपका एक मित्र एक train में बैठा है और वो train 100 किलोमीटर प्रति घंटे की रफ्तार से आपके सामने से गुजरती है। जैसे ही train आपके सामने से गुजरी तो आपने देखा की आपका मित्र भी उस train के साथ 100 किलोमीटर प्रति घंटे की रफ्तार से जा रहा है। ठीक उसी समय train में बैठा आपका दोस्त देखता है कि ट्रेन में अन्य लोग भी बैठे हैं और वह स्थिर हैं। मतलब train में मौजूद सभी व्यक्तियों की गति जीरो है।

अब इसमें यह समस्या उत्पन्न होती है कि train की गति का माप किस के अनुमान पर निर्धारित किया जाए। train में बैठे व्यक्ति के अनुमान या platform पर मौजूद व्यक्ति के अनुसार। जवाब था कि दोनों अपनी अपनी जगह सही है। किसी भी वस्तु की गति का मान इस बात पर निर्भर करता है कि उसका अनुमान स्थिर हो कर लगाया जा रहा है या गतिशील होकर।

इसका निष्कर्ष यह था कि गति निरपेक्ष (irrespective) नहीं बल्कि सापेक्ष (respective) है। अगर आसान भाषा में कहें तो गति का निर्धारण इस बात पर निर्भर करता है कि वह किस के सापेक्ष है। जैसे पृथ्वी अपनी दुरी पर घूम रही है लेकिन हमें महसूस होता है कि पृथ्वी स्थिर है और हम भी स्थिर हैं। लेकिन अंतरिक्ष से देखने पर पृथ्वी हमें घूमती हुई नजर आएगी। पृथ्वी से सूर्य हमें स्थिर लगता है। लेकिन अगर आकाशगंगा की दृष्टि से देखा जाए तो सूर्य Milkiway Galaxy की परिक्रमा कर रहा है।

17 वीं सदी में भौतिक विज्ञान में relativity का पहला सिद्धांत दिया गया कि स्थिर या एक समान गति की अवस्था में भौतिकी के नियम नहीं बदलेंगे। आसान भाषा में कहें तो platform पर बैठे आप अगर भौतिकी का कोई प्रयोग कर रहे हो और उसी प्रयोग को गतिशील train में बैठा आपका दोस्त भी कर रहा है तो दोनों के परिणाम समान होंगे।

Theory of relativity का जन्म (Origin of theory of relativity) :

Newton के समय से चली आ रही इस classical theory of relativity नामक सिद्धांत को 19वीं सदी में आकर चुनौती मिली। जब मैक्सवेल (maxwell) नामक वैज्ञानिक के सिद्धांतो पर प्रयोग किया गया। तो पाया कि ब्रह्मांड में एक ऐसी भी गति मौजूद है जो किसी के साथ respective नहीं बल्कि irrespective है और उसका माप स्थिर है। वह है प्रकाश की गति जिसका माप 3 लाख किलोमीटर प्रति सेकंड है। Michaelson और Morley नामक वैज्ञानिकों ने यह साबित किया कि प्रकाश की गति किसी भी माध्यम पर निर्भर नहीं करती। अब चाहे आप प्रकाश की गति को स्थिर होकर देखो या किसी तेज गति से चलने वाली train में बैठ कर देखो।

Albert Einstein ne kya khoj ki thi

इसको एक उदाहरण से समझते हैं: मान लो कि आप platform पर बैठे हो और आपका दोस्त 50 किलोमीटर प्रति घंटे की रफ्तार से चल रही ट्रेन में बैठा है। जब आप अपने दोस्त को platform से देखते हो तो आपने देखा किया कि आपका दोस्त 50 किलोमीटर प्रति घंटे की रफ्तार से जा रहा है। लेकिन अब मान लो की आपका दोस्त train  की गति कि दिशा में 10 किलोमीटर प्रति घंटा की रफ्तार से दौड़ता है। तो अब आपने देखा कि आपके दोस्त की गति 60 किलोमीटर प्रति घंटा हो गई। क्योंकि आपकी दोस्त की भी गति उस train की गति में जुड़ गई।

अब इस वाक्य को आगे देखते हैं वैसे ऐसा कभी होगा तो नहीं लेकिन फिर भी मान लो की अब train की गति प्रकाश की गति के बराबर है। और प्रकाश की गति से चलती ट्रेन में जब आपका दोस्त ट्रेन की गति की दिशा में प्रकाश की गति से दौड़ता है। ऐसी परिस्थिति में platform से देखने पर आपको आपके दोस्त की गति प्रकाश की गति कि दोगुनी दिखनी चाहिए लेकिन सत्य तो यह है कि आपको अपना दोस्त प्रकाश की गति से ज्यादा हुआ नजर आएगा। प्रकाश की गति absolute है जो कि किसी पर निर्भर नहीं करती है यानी है स्थिर और कभी भी बदलती नहीं है।

यह भी पड़े : String Thoery और Thoery of relativity में क्या अंतर है?

अल्बर्ट आइंस्टीन के आविष्कार

19 वीं सदी का अंत और 20वीं सदी की शुरुआत विज्ञान की दृष्टि से बेहद खास है क्योंकि यह वह दौर था जब phyices में क्रांतिकारी सिद्धांत सम्मिलित हुए हैं। और यही वह दौर था जिसमें Albert Einstein ने physics की दुनिया में अपना योगदान दिया। वह एक ऐसे व्यक्ति थे जिनकी अवधारणा कल्पना में जन्म लेती थी और शौधों द्वारा साबित होती थी। जहां पर आम लोगों की सोच खत्म होती थी वहां से उनकी की सोच शुरू होती।

Albert Einstein ने कल्पना की ऐसा क्या कारण है कि हर स्थिति में प्रकाश की गति हमेशा constant यानी नियत रहती है। उन्होंने सोचा की ऐसी क्या घटना घटेगी जब वह प्रकाश की गति से travel करेंगे। कल्पना करने के साथ-साथ उन्होंने गति के Formula को भी ध्यान में रखा। उन्होंने अपनी कल्पना में पाया की किसी भी चीज की गति दूरी और समय के अनुपात (proportion)पर निर्भर करती है। अगर प्रकाश की गति constant है इसका मतलब की गति में कोई भी बदलाव नहीं हो रहा है बल्कि  दूरी और समय अपने आप को बदल रहे हैं।

उन्होंने बताया कि प्रकृति अपने fundamental laws को टूटने नहीं देती बल्कि इनका बचाव करती है। और प्रकृति का ऐसा ही एक fundamental law है प्रकाश की गति जो कि 3 लाख किलोमीटर प्रति सेकंड है। जो किसी भी स्थिति में नहीं बदलती और प्रकृति fundamental law यानी प्रकाश की गति को एक समान रखने के लिए space और time को ही बदल देती है। Albert Einstein  का यह concept physics की  दुनिया में तहलका मचाने के लिए तैयार था।

सापेक्षता का सिद्धांत उदाहरण

चलिए Einstein के concept  को आसान भाषा में समझने का प्रयास करते हैं। इसके लिए हम अपने पुराने उदाहरण को लेते है । मान लो कि आपका दोस्त जो प्रकाश की गति से चलने वाली ट्रेन में बैठा है उसके पास एक घड़ी है और आप एक platform पर बैठे हो और आपके पास भी एक घड़ी है। जब आपका दोस्त train में बैठा उस समय आप की घड़ी का समय और आपके दोस्त की घड़ी का समय एक समान है। अब आप platform पर खड़े होकर उस प्रकाश की गति से चलने वाली train को देख रहे हो। जिसमें आपका दोस्त बैठा है आपने देखा कि जो प्रकाश की गति से चलने वाली train थी उसकी लंबाई बहुत कम हो गई है और train में आपके दोस्त के पास जो घडी मौजूद है उसका समय आपकी गाड़ी की समय की अपेक्षा बहुत दीमी रफ्तार से चल रहा है।

इसका कारण है कि प्रकृति अपने fundamental law को टूटने से बचा रही है। इस वजह से train की गति प्रकाश की गति के बराबर रखने के लिए space और time दोनों ही बदल गई यानी train की लंबाई और train में मौजूद घडी का समय दोनों ही बदल गए।

टाइम ट्रेवल

यह घटना तो आपने platform पर खड़े होकर देखी लेकिन वहीं दूसरी ओर जो आपका दोस्त train में बैठा है उसके लिए कोई भी बदलाव नहीं हुआ। मतलब train में बैठा आपका दोस्त महसूस करता है कि train की लंबाई वही है जो पहले थी। और उसके पास जो घडी मौजूद है उसमें समय की रफ्तार में कोई बदलाव नहीं आया है। मतलब आप platform से देख रहे हो कि आपका दोस्त जिस train में बैठा है उसकी लंबाई भी कम हो गई और समय भी धीमा हो गया। लेकिन आपके दोस्त के नजरिए से सब कुछ normal चल रहा है। लेकिन आप दोनों ही अपनी अपनी जगह सही हो यह तो प्रकृति का कमाल है। जिसमें दोनों की नजरियों को बदल दिया।

लेकिन जब एक हफ्ते के सफर के बाद आपका दोस्त train से बाहर निकलेगा तो वह इस दुनिया में बहुत बड़ा बदलाव देखेगा। वो देखेगा उसके पास जो घड़ी थी उसके अनुसार अभी एक हफ्ता ही हुआ है । लेकिन आपकी घड़ी के अनुसार पृथ्वी पर सालों बीत चुके हैं। क्योंकि आपकी घड़ी के मुकाबले आपके दोस्त की घड़ी धीमी चल रही थी आपका दोस्त आपको देखेगा कि आप पहले से बूढ़े हो चुके हो। लेकिन उसकी उम्र पर कोई फर्क नहीं पड़ा इसी को आप अपने दोस्त के लिए भविष्य की दुनिया बोल सकते हो जिसमें वह 1 हफ्ते के सफर के बाद पहुंच गया लेकिन अब वह भविष्य के उस दौर से वापस नहीं लौट सकता।

यह भी पड़े : Quantum Physics क्या है ? Albert Einstein का क्वांटम फिजिक्स में योगदान क्या है ?

special theory of relativity in hindi

Albert Einstein की space और time की इस कल्पना ने क्रांतिकारी concept यानी time travel जैसी अवधारणा को जन्म दिया। इससे पहले लोगों का यही मानना था कि ब्रह्मांड में प्रत्येक जगह पर समय की रफ्तार एक समान है लेकिन Einstein ने बताया कि ब्रह्मांड में प्रत्येक जगह time और space अपने आप को परिस्थिति के अनुसार बदलते रहते हैं।

उन्होंने space और time का यह concept mathematical equations के आधार पर सिद्ध कर दिया था। लेकिन इस पर परीक्षण करना अभी बाकी था। 1977 में नासा ने satellite में कुछ घडीयां लगाकर छोडी जिनका समय पृथ्वी की घड़ी के अनुसार set किया गया था। लेकिन अंत में जाकर satellite की घड़ियों का समय पृथ्वी पर मौजूद घड़ियों से धीमा चल रहा था। हालांकि पृथ्वी की घड़ियों और satellite में लगी गाड़ियों के समय का अंतर बहुत ही मामूली था। लेकिन कहीं ना कहीं Albert Einstein के सिद्धांत की सहायता की।

हमारे इतना विकसित होने के बावजूद भी हमारे पास ऐसी technology नहीं है जो Einstein के सिद्धांत को साबित कर पाए। क्योंकि उनके सिद्धांत को साबित करने के लिए हमारे पास प्रकाश की गति से चलने वाला Spacecraft होना चाहिए जो कि हमारे लिए अभी असंभव है। 1905 के आसपास एक clerk की हैसियत से काम कर रहे इस इंसान ने अपनी special theory of relativity का पेपर लिखा। लेकिन सदी के इस महान वैज्ञानिक की कल्पना यहीं नहीं रुकी यही वह दौर था जब Einstein ने अपनी theory of relativity in hindi को आगे बढ़ाते हुए एक equation दी जो हमेशा के लिए उनके नाम से जुड़ गई जो है E= mc² इसका मतलब है किसी भी वस्तु के mass को energy में बदला जा सकता है और energy को mass में बदला जा सकता है।

E mc2 hindi

Albert Einstein ने बताया कि mass भी समय की तरह relative है मतलब किसी भी वस्तु की गति बढ़ाने पर उसका mass भी बड़ेगा। वह भी वस्तु के आकार में बदलाव किए बिना। Einstein के इस equation E=mc²   के आधार पर वैज्ञानिकों ने आगे चलकर परमाणु बम (nuclear bomb) का निर्माण किया जिसका इस्तेमाल  world war 2 के दौरान पहली बार हुआ और नागासाकी शहरों का अस्तित्व ही खत्म हो गया। उस समय Albert Einstein को अपनी equation E=mc² देने का बड़ा दुःख हुआ और उन्हे लगा कि इस equation का आधार बनाकर दुरुपयोग हुआ है।

Space और Time absolute नहीं है Einstein ने यह साबित किया। लेकिन उनके दिमाग में अभी भी खलबली मची हुई थी कि space और time accelerated frame में किस तरह से बर्ताव करेंगे। जैसा कि मैंने पहले ही कहा था जिनकी सोच बड़ी होती है उनके कारनामे भी बड़े ही होते हैं।

साइंस किताबें

अगर आप भी किताबें पढ़ने के शौकीन हैं और खाली समय में साइंस के लोकप्रिय सिद्धांतों पर आधारित किताब पढ़ना चाहते हैं तो यह हमारी तरफ से टॉप साइंस किताबें हैं जो आप पढ़ सकते हैं:

[…] का इस्तेमाल किया जाता है। पहली theory है General theory of relativity और दूसरी है Quantum mechanics। सर ईसेक न्यूटन ने […]

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Theory of Relativity in Hindi | Albert Einstein | Time Travel | Length Contraction and Time Dilation Video Lecture - Class 11

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थ्योरी ऑफ रिलेटिविटी (सापेक्षता सिद्धांत) क्या है?

By अनुश्री कनोडिया

विषय-सूचि

सापेक्षता सिद्धांत का मतलब (theory of relativity meaning in hindi)

रिलेटिव का मतलब होता है सापेक्ष होना। थ्योरी यानी सिद्धांत।

ऐसे में थ्योरी ऑफ रिलेटिविटी का मतलब है किसी भी वस्तु या प्राणी की गतिविधि को किसी अन्य वस्तु या प्राणी के सापेक्ष/दृष्टि से देखना।

इसे हम दो भागों में बाट सकते हैं। जनरल (सामान्य) थ्योरी ऑफ रिलेटिविटी और स्पेशल (विशेष) थ्योरी ऑफ रिलेटिविटी।

इनर्शियल/नॉन इनर्शियल फ्रेम ऑफ रिफरेन्स

इनर्शियल फ्रेम वह होता है जिसमे सारी वस्तुएँ एक दूसरे के सापेक्ष लगातार एक ही गति से चल रही हों। एक वस्तु की गति, दूसरे के रिलेटिव ना बदले। इस फ्रेम में न्यूटन द्वारा दिया गया प्रस्ताव का पहला कानून (फर्स्ट लॉ ऑफ मोशन) मान्य होता है।

जबकी नॉन इनर्शियल फ्रेम वह है जिसमे त्वरणयुक्त ( एक्सेलरेटेड ) मोशन हो। इस फ्रेम में न्यूटन का फर्स्ट लॉ ऑफ मोशन मान्य नहीं होता।

सामान्य सापेक्षता सिद्धांत (general theory of relativity in hindi)

जनरल थ्योरी केवल इनर्शियल( जड़त्वीय ) फ्रेम ऑफ रिफरेन्स में ही मान्य है। इसे समझने के लिए हम एक उदाहरण से शुरुआत करते हैं। मान लीजिए सड़क पे एक गाड़ी 30kmph की रफ़्तार से पूर्व से पश्चिम की ओर जा रही है। गाड़ी में रोहन और उसका दोस्त राज बैठा है। और आप सड़क के किनारे खड़े हैं। रोहन के लिए राज स्थिर है और एक ही जगह पर है। परंतु आपके लिए वो दोनों 30kmph की गति से पश्चिम जा रहे हैं। और उनके लिए आप 30kmph से पूर्व जा रहे हैं। ये तीनों ही निष्कर्ष सही है। फर्क है तो बस फ्रेम ऑफ रिफरेन्स का। अब अगर रोहन पश्चिम दिशा में 10 kmph की गति से एक गेंद फेकता है, तो रोहन के लिए वह गेंद 10 kmphसे ही जाएगी। पर आपको लगेगा कि गेंद 30+10( गाड़ी + गेंद ) =40kmph की गति से पश्चिम जा रही है।

हम ये तो जानते ही हैं कि प्रकाश की गति अटल है -3,00,000 किलोमीटर प्रति सेकंड। तो अगर रोहन ने पश्चिम की ओर टोर्च की होती तो क्या हमें प्रकाश की गति बढ़कर लगेगी? नही। ऐसा संभव नहीं।

दुनिया मे कुछ भी प्रकाश की तय गति से तेज़ नही चल सकता। अगर कुछ भी बहुत तेज़ या प्रकाश जितनी तेज़ गति से चलता है, तो उसकी रिलेटिव गति तो स्थिर रखने के लिए उसकी लंबाई और समय में बदलाव आते हैं। इसे अंग्रेज़ी में टाइम डायलेशन और लेंथ कंट्राडिक्शन कहते हैं।

टाइम डायलेशन मतलब समय का धीरे चलना। जो भी वस्तु इतनी तेज चलेगी, उसका समय धीरे बीतेगा। अर्थात गर आप प्रकाश की गति से कोई दूसरे ग्रह चले जाए और वापिस आ जाएँ, तो आप धरती पे अपना भविष्य देखेंगे। लेंथ कंट्राडिक्शन यानी कि उस तेज़ चलने वाली चीज़ की लंबाई काम हो जाना। इस थ्योरी से साबित हुआ कि समय पूर्ण नहीं रिलेटिव होता है। वो हर किसी के लिए अलग अलग चलता है।

विशेष सापेक्षता सिद्धांत (special theory of relativity in hindi)

जनरल थ्योरी सिर्फ इनर्शियल फ्रेम में ही मान्य है। लेकिन ब्रह्मांड में कुछ भी एक गति से नहीं चलता। सब कुछ त्वरणयुक्त है। जिसका अर्थ ये हुआ कि जनरल थ्योरी असल दुनिया में लागू ही नहीं होती। इस कमी को सुधारने के लिए स्पेशल थ्योरी ऑफ रिलेटिविटी दी गई।

ये थ्योरी गुरुत्वाकर्षण से संबंधित है। हम जानते हैं कि तीन आयाम (डाइमेंशन्स) होते हैं। जिन्हें x,y और z से संबोधित किया जाता है। आइंस्टीन का कहना था कि समय चौथा डायमेंशन है।

सोचिए कि आपसे ज़मीन पर पानी गिर गया। तो कुछ ही देर में पानी इधर उधर फैलेगा और अलग अलग आकार लेगा। इसको हम एक चलचित्र की तरह देख सकते हैं जो कि समय के साथ बदलता है।

स्पेस टाइम को एक फैले हुए कपड़े की तरह मानते हैं जिसपे भार (मास) के कारण वक्र आते हैं। जितना ज्यादा भार, उतना ज्यादा वक्र। गुरुत्वाकर्षण भी वक्र के कारण की लगता है।

ये भी माना जाता था कि प्रकाश एक सीध में चलता है। परंतु इस थ्योरी से प्रमाणित हुआ कि प्रकाश को मोड़ा जा सकता है। और जो वस्तु जितनी भारी, उससे टकराने के बाद प्रकाश उतना ही ज़्यादा मुड़ेगा। प्रकाश के मुड़ने की वजह से ही हम सूर्य के पीछे के तारों को देख पाते हैं।

आश्चर्यजनक तो ये खोज थी कि समय गुरुत्वाकर्षण से भी संबंधित है।जहाँ गुरुत्वाकर्षण तीव्र, वहाँ समय धीमे बीतता है, जैसे कि पृथ्वी का केंद्र। और जहाँ गुरुत्वाकर्षण कम, वहाँ समय जल्दी बीतता लगता है, जैसे ऊंचे पर्वत। इसी खोज के कारण आज जीपीएस सिस्टम बन पाया है।

इस लेख से सम्बंधित यदि आपका कोई सवाल या सुझाव है, तो आप उसे नीचे कमेंट के जरिये हमसे पूछ सकते हैं।

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राष्ट्रीय विज्ञान दिवस 2024 की थीम ‘विकसित भारत के लिए स्वदेशी तकनीक’ हुआ लॉन्च, मौसम विभाग ने मनाया 150वां स्थापना दिवस, इसरो 21 अक्टूबर को गगनयान टेस्ट वाहन अंतरिक्ष उड़ान का आयोजन करेगा: डॉ. जितेंद्र सिंह, 30 thoughts on “थ्योरी ऑफ रिलेटिविटी (सापेक्षता सिद्धांत) क्या है”.

theory of relativity ka real life mein kya use hai? ye topic bahut saare exam smein aataa hai.

Theory of relativity brahmand ke niyam ko samjhane me madat karti hai jaise prakash ki gati hamesha samaan rahegi jab ham kisi vastu ko dekhte hain to yah observer par nirbhar karta hai ki wah vastu use kis state me dikhegi

Now present technology ke according it is imposible . Because iske liye large amount me fuel & energy source chahiye . Therefore , present me ham light ke speed se travel nahi kar sakte. Thank you .

inertial and non inertial frame of reference kyaa hote hain and in donon frame of reference mein kyaa kyaa difference hote hain??

Time gravitation se related hota hai ye theory kisne do thi us scientist ka Kya. Naam hai?

Sir Albert Einstien ne bataya tha ki samay gravity se related hai

Black holes dikhte kyo nahi . Isaka karan mai janta hu.

Kya agr hm prakash ki gati se tej vastu ka niman kr le to kya hm time travel kar skte he ? Please reply me…. Thank you

Hn Q ki light ki speed pr koi bhi science ka niyam kaam nahi krega or tum 4 D me honge Q ki time he 4D hai….or tumhare time bohot slow ho jayega tumhari age normal hogi or earth pr tumhara chota bhai tum se bada ho jayega just like tum jb ghar se gye tum 25Y k the or tumhara Bhai 20Y tumne 5 year light speed se chale to jb vapas earth pr aaoge tb tumhara bhai 35Y ho jayega or tum 30Y

है क्यों नही ऊपर एक लेख में लिखा गया है की अगर हम light के बराबर या उससे तेज चलने वाली कोई भी चीज का निर्माण कर लिया या उससे तेज चले और किसी अन्य ग्रह पर light की speed से travel करे तो हम पृथ्वी पर अपना भविष्य देख सकते है

Kya time machine banaanaa sambav hai

GPS system kaise bana puri jankari dijiye please

GPS system Kaise Bana puri jankari dijiye please

Hello uncle Backing time machine sambhav hai

Ho ya nhi Hello

Kya koi aesi machine ban sakti hai? Jo light se tej ja ske? Please btaye, !

माना कि हम प्रकाश की गति से गति कर सकते है।माना कि हम पृथ्वी से मंगल ग्रह पर प्रकाश की गति से गति करते हुए 12 मिनट में पहुंच गए और फिर उसी गति से वापस पृथ्वी पर 12 मिनट में आ गए तो हमारे द्वारा कुल 24 मिनट समय लिया गया।क्या इस 24 मिनट बाद जब हम पृथ्वी पर लौटेंगे तो अपना भविष्य कैसे देख लेंगे…?

ya bhavishya dekhi ka matlab khud apna bhavishya dekhna nai hai apitu dharti ke samya ka bhavishya se hai yani ki jab hum dharti per wapas aayenge to dharti per 24 minutes se jyda beet chuke honge

Kya hum Parkaas ki gati ke brabar chal ya koi ROCKET bej sakte hai kahi bi Mangal ya koi dusre greh par..

it is imposible

Mera comment yeh hai ki agar hamari prathavi ke Kendra par time dhima hota hai to ye batao ki space me to time gatishil (fast) Hoga

einstein ki theory of relativity

इस थ्योरी को में

“मनु” जिन्होंने मनुस्मृति को लिखा है

उनके माता पिता से जोड़ कर समझना चाहता हूं

तो मेरा सवाल यह है कि “मनु के माता पिता कोन थे और उनके क्या नाम थे”

When any things faster than light then why required his relative motion is constant or rest

agar hum time treval kare to aur hum future me chale jaaye to kya hum present time me vapas aa sakte hai please reply me sir

sir hame pata hai ki same chages reples karte hai to jo charge earth ka hai agar wahi charge hum kisi object par wahi charge rakhe to kya wah object replese hogi ? agar replece hoti hai to wah object earth se dur jayegi jesse hum space me bina kisi fule kharch kiye jaa sakte hai. sir agar mera theory sahi hota hai to hum earth yaa space me bina kisi fule ke hum treval kar payenge . aur hume ummed hai ki hum light ki speed se travel kar paayen . sir my phone no – 7491864716

agar insaan “light ki speed se travel karna possible nahi hai” bol raha hai to wo aysa is liye bol raha hai kyoki abhi waise koi sadhan nhi hai hamery pass . lekin in future me ayse nhi hoga ye jarouri thodi hai . agar student ko sari subidha milega tab na kuch naya khoj karega . or aap ne bhout he achi post likhi hai . thanks i love physics.

Time kase or kyu change hota ha ?

हम धरती चंद और मंगल ग्रह को जानते हैं .हमने सबसे पहले दूरी इन तीनों का कब नापा था . अब तक कितना फरक है ? अगर फरक है तो newton law गलत हैं अगर जो नही हैं तो सही हैं ,ये फरक बहुत कम होगा.kaya

ऊपर लिखा हैं की जहाँ गुरुत्वाकर्षण कम होता हैं वह समय तेज बीतता है। तो स्पेस में तो गुरुत्वाकर्षण होता ही नही ह तो वह समय धीमा कैसे बीतता हैं।और धरती पे तीव्र होता ह तो, समय तेज कैसे बीतता है।।रिप्लाई करे…….

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फेयरनेस क्रीम के बढ़ते इस्तेमाल से भारत में किडनी की समस्याएँ बढ़ रही हैं: अध्ययन

Election 2024: जलवायु परिवर्तन जैसे पर्यावरण संबंधी समस्याएं भारत मे चुनावी मुद्दा क्यों नहीं बनतीं, katchatheevu island: प्रधानमंत्री मोदी आखिर इस ‘गड़े मुर्दे’ को क्यों उखाड़ रहे हैं, kangana ranaut row: महिलाओं के प्रति द्वेष वाली राजनीति का एक नमूना..

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ALBERT EINSTEIN - HINDI - FOUNDER OF THEORY OF RELATIVITY

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Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

If you liked this, you may like:

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Einstein and Time Travel – His Theories

Cristina Boros April 17, 2016 16 Comments

Einstein and time travel , Einstein theories , theory of relativity

Welcome, and I am very happy to have you here again today 🙂 and talk to you about Albert Einstein and time travel.

Let’s have a look at the scientific part of this subject of time travel. Do you think time travel is just fiction found in movies, books, and games, or could it be a future reality?

We have had some great minds of the century some offered theories, one of them being by the physicist Albert Einstein. So, talking about Einstein and time travel let’s try to understand his theories.

I know it is not a very simple subject but I also think many of you would like to know his ideas, so I will try to explain them as clearly and as simple as I can.

I am not a physicist myself so let’s see in simple terms what Einstein proved with his theories.

The Theory of Special Relativity

First of all, Einstein proved that time is relative; a very different opinion from Newton who claimed that time is absolute. But which one was right? How did Einstein sustain his theory?

His theory says that when you move through space-time at the speed of light, time goes slower for you than for the others.

For example

Travelling with a very fast spaceship, one person would get older by only a few days whereas another who is on the earth, by month or years.

It is said that the faster we travel, the slower time passes.

In 1905, Einstein explained in this theory time-space as a fourth dimension.

  To prove this theory, in 1975 Carol Allie made an experiment at the University of Maryland.

Two clocks were synchronized and one was placed on an airplane and another in the laboratory.

When the clock that was placed on the aircraft returned after a few hours of flight, it was seen to be a fraction of a second faster than the clock that remained in the laboratory.

Ok, this is an experiment on a small scale, but what if the clock was placed on a spaceship that flew at the speed of light?

Einstein claims that for a time travel journey to be successful, you would need to be able to travel at the speed of light.

So according to his theory, Einstein claims that traveling at a speed close to the speed of light will slow the time, reaching the speed of light will stop time and if it will be ever possible to pass the speed of light, time will reverse.

General Relativity – Einstein’s Theory

  Another theory of this great physicist was that time passes slower for objects in a gravitational field than for an object which is far from such a field.

So here we have black holes, where the gravity is intense.

Kip Thorne (University of California) claimed that wormholes do exist in space and that they are shortcuts to the past. If two wormholes are connected, it could make a passageway to the past or future.

His theory was confirmed in 1919 when during a solar eclipse, astronomers measured the curving of starlight around the Sun.

One more time in 1922, during another sun eclipse confirmed Einstein was right and he became famous worldwide.

Even today flights are based on his theory.

Researchers today say that they have detected gravitational waves coming from two wormholes that crashed together, located at a distance 1.3 billion light years away.

Physicists say that it is difficult to succeed in time travel because, in our world, the laws of physics are not pushed to the limit, but if we could break these rules, time travel would be possible.

Breaking the Rules

Many physicists have tried to violate Einstein’s theories or to ‘break the rules’.

Marian Scully, Lijun Wang, Gunter Nimtz, and Alfons Stalhofen are some of those names who claimed that they have succeeded in violating these theories.

The last two, at the University of Koblenz, transmitted photons at a speed faster than the speed of light, so the photons traveled into the past.

I will not write about each one because it is pure science, physics, and calculus. It would take a mind such as Einstein to understand it.

Based on Einstein theories, the novelist H.G. Wells wrote the novel ‘The time machine’ and physicists think that he was really onto something.

Einstein’s equation E=mc2 proves that time travel into the past is possible theoretically and scientists say that if it is still impossible for us to put this into practice, it doesn’t mean that time travel is impossible.

Stephen Hawkins says about Einstein’s theories, that to travel with a speed faster than light is almost impossible, at least in our world, and if time travel will ever be possible the past will make you stop.

The laws of physics are made not to allow us to change the past.

Now, what to think?

Reading so many different opinions I can understand just one thing. Time travel is possible but we need a more advanced technology to break the laws of physics, to use gravity and travel at the speed of light.

Does the past want to be changed?

I understand that it would be really fascinating if we could do this, but maybe this is too much?

David Lewis gives a good example of this talking about compossibility and the ability to change the past.

It is true that changing past events would have many implications, and practically it is impossible.

Lewis gives as an example

Tim, a man that hates his grandfather wants to travel into the past and kill him.

Would it be possible?

If the grandfather is killed when he is young, this would mean Tim’s parents would not exist, so Tim would also not exist to kill him.

If for example the grandfather normally dies in 1993 and Tim goes back to 1955 to kill him, would he?

Considering the present and that the grandfather should live for Tim to exist, (I will not confuse you more), Tim will be stopped from the past to succeed in killing him.

Lewis’s conclusion and exact quote is:

‘Tim doesn’t but can because he has what it takes ‘(clear shot, daylight) and also he believes that if Tim finally tries to do it, everything will stop him, a bird will fly in front of him, the gun will jam or he will just fall every time he will want to shot his grandfather.

This paradox can also be seen in many films.

So what is your conclusion?

Reading all these theories and ideas, what do you really think?

Is time travel possible only theoretically, or if we push a little bit harder on the laws of nature, can we do

I would like to know your opinion and if you have any questions just ask.

I look forward to hearing from you all and thanks for reading.

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16 Comments

Hi Cristina,

I just bumped into your site. That is a very informative and quite interesting article on time travelling.

So many historical personalities delved into the matter, many of them you mention in your post.

Humans are extrordinary creatures when and if they want to so I wouldn’t be surprised if that became a reality in the future.

I hope I am alive to experience it.

thanks for reading and i hope too, one time will see it real. i am the first to try :))i fell we are close

Hello Cristina, appreciate your post and very exited to read about Travel travel theories. There is nothing impossible and if the scientist put full focus on law of nature theories, we can achieve the time travel goal. However this technology should be limitedly used for example to see our earth some 5000, 10000 etc years back and future as well like year 5050. Awesome to imagine this. However all the best! Thanks

thank you for your reading and of course, if will ever be possible time travel should be used for very good reasons:)Thanks again and soon, more articles will bring the news:)

Hi, I loved all the science. I took time to view your video. It was interesting and I learned some information I didn’t know before.

Traveling in time is an intriguing idea. On the one hand I would like to see time travel become a reality. On the other hand changing time could be a problem.

One of my favorite books is The End of Eternity by Isaac Asimov. Thanks, Dave

thank you for reading. yes I think you are absolutely right if it will ever be possible time travel, i don’t think is a good idea for everyone to be able to do it .about the book i will read it and i will tell you my opinion:) thanks again

I just watched 12 monkeys and time travel is one of my favorite genres when watching TV shows and movies. I also watched a documentary of Einsten’s life and I got a gist of his theory of time-space, but still I cannot get the bending and the solar eclipse experiment. But I did enjoy the documentary. Honestly, if I could change the past, I would but my senses are telling that it is very far from reality, and may not happen in this lifetime. That is why I enjoy entertainment about it, so at least I feel contentment. How about you? How do you feel about time travel?

to be honest, I think is possible but not for everyone. It is still researched and i think that if we don’t know yet the way to do it , the ancient civilization sure did. and there are proves that there are time travelers but coming from the future . thanks for reading and I am glad that you enjoy it 🙂

Hi Cristina,I myself believe in time travel and think Einsteins theory is right on.I enjoyed your article very much, thought it was very interesting.Nice job

me too, to be honest, I believe. This is the reason i write about it and I search so many things, I am glad that you enjoyed it and stay around, 🙂 i will write more articles and I hope you will like them:)

I am seriously mind blown right now. The experiment you mentioned back in 1975 is awesome! I would like to know if they have done anymore like this recently with faster planes. I agree that we are bound by the laws of physics, but i really think that we can get over it with technology advancing more and more everyday!. I enjoyed reading this article!

i am happy that you enjoyed reading my article . i think experiments are done every year and the technology advances day by day but as soon as i know about something new… i will write about :)) i am sure in a few year you will have big surprises about faster planes . thanks 🙂

This is the most interesting article I have ever read in my life! Ok so in my opinion, I believe that time travel is possible, maybe not in our lifetime but it’s definitely possible. I mean just look at how far we’ve come over the past 15 years. Now I know that in order to travel to the past or to the future you have to travel faster than the speed of light, which is time in space.

I believe in time that we will eventually be able to live on multiple planets as technology and our resources get more and more advanced. Great article!

I also think in the future we will leave on other planets 🙂 It is also planned to colonize Mars so..it is not too far:)

Do you think not in out life time? Maybe, who knows:) 

Thanks for reading and if you want to know more there are plenty of articles on my site so..have a nice time and if I can help , ask me anything:)

Interesting read! I was never 100% sure if I believed in time travel being real, but, I generally do enjoy hearing other stories and theories about that!

As far as Albert Einstein goes, I probably should learn more about him, as he seems to be one of the smartest men to live.

One thing I was not aware of was that the speed at which we travel impacts the speed at which time progresses!

His theory on going at the speed of light has me wondering, would this send one towards the future or the past? And would there be a deciding factor in terms of how far beyond or backwards in time?

I am also somewhat curious to know how he came up with this theory. Do you have an opinion on this?

Hello there:) Arie

In Einstein’s opinion based on his theories time travel can be done in the future is we travel with a speed faster than the speed of light. Not in the past.How he came up with it? He came up with this idea in 1905 , 200 years after Newton wrote about the law of motion.he publishes his theory in 1915, after ten years of studies. So hew exactly came up is a long story and I will write a post very soon stay close:)

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A beginner's guide to time travel

Learn exactly how Einstein's theory of relativity works, and discover how there's nothing in science that says time travel is impossible.

Everyone can travel in time . You do it whether you want to or not, at a steady rate of one second per second. You may think there's no similarity to traveling in one of the three spatial dimensions at, say, one foot per second. But according to Einstein 's theory of relativity , we live in a four-dimensional continuum — space-time — in which space and time are interchangeable.

Einstein found that the faster you move through space, the slower you move through time — you age more slowly, in other words. One of the key ideas in relativity is that nothing can travel faster than the speed of light — about 186,000 miles per second (300,000 kilometers per second), or one light-year per year). But you can get very close to it. If a spaceship were to fly at 99% of the speed of light, you'd see it travel a light-year of distance in just over a year of time. 

That's obvious enough, but now comes the weird part. For astronauts onboard that spaceship, the journey would take a mere seven weeks. It's a consequence of relativity called time dilation , and in effect, it means the astronauts have jumped about 10 months into the future. 

Traveling at high speed isn't the only way to produce time dilation. Einstein showed that gravitational fields produce a similar effect — even the relatively weak field here on the surface of Earth . We don't notice it, because we spend all our lives here, but more than 12,400 miles (20,000 kilometers) higher up gravity is measurably weaker— and time passes more quickly, by about 45 microseconds per day. That's more significant than you might think, because it's the altitude at which GPS satellites orbit Earth, and their clocks need to be precisely synchronized with ground-based ones for the system to work properly. 

The satellites have to compensate for time dilation effects due both to their higher altitude and their faster speed. So whenever you use the GPS feature on your smartphone or your car's satnav, there's a tiny element of time travel involved. You and the satellites are traveling into the future at very slightly different rates.

But for more dramatic effects, we need to look at much stronger gravitational fields, such as those around black holes , which can distort space-time so much that it folds back on itself. The result is a so-called wormhole, a concept that's familiar from sci-fi movies, but actually originates in Einstein's theory of relativity. In effect, a wormhole is a shortcut from one point in space-time to another. You enter one black hole, and emerge from another one somewhere else. Unfortunately, it's not as practical a means of transport as Hollywood makes it look. That's because the black hole's gravity would tear you to pieces as you approached it, but it really is possible in theory. And because we're talking about space-time, not just space, the wormhole's exit could be at an earlier time than its entrance; that means you would end up in the past rather than the future.

Trajectories in space-time that loop back into the past are given the technical name "closed timelike curves." If you search through serious academic journals, you'll find plenty of references to them — far more than you'll find to "time travel." But in effect, that's exactly what closed timelike curves are all about — time travel

This article is brought to you by  How It Works .

How It Works is the action-packed magazine that's bursting with exciting information about the latest advances in science and technology, featuring everything you need to know about how the world around you — and the universe — works.

There's another way to produce a closed timelike curve that doesn't involve anything quite so exotic as a black hole or wormhole: You just need a simple rotating cylinder made of super-dense material. This so-called Tipler cylinder is the closest that real-world physics can get to an actual, genuine time machine. But it will likely never be built in the real world, so like a wormhole, it's more of an academic curiosity than a viable engineering design.

Yet as far-fetched as these things are in practical terms, there's no fundamental scientific reason — that we currently know of — that says they are impossible. That's a thought-provoking situation, because as the physicist Michio Kaku is fond of saying, "Everything not forbidden is compulsory" (borrowed from T.H. White's novel, "The Once And Future King"). He doesn't mean time travel has to happen everywhere all the time, but Kaku is suggesting that the universe is so vast it ought to happen somewhere at least occasionally. Maybe some super-advanced civilization in another galaxy knows how to build a working time machine, or perhaps closed timelike curves can even occur naturally under certain rare conditions.

This raises problems of a different kind — not in science or engineering, but in basic logic. If time travel is allowed by the laws of physics, then it's possible to envision a whole range of paradoxical scenarios . Some of these appear so illogical that it's difficult to imagine that they could ever occur. But if they can't, what's stopping them? 

Thoughts like these prompted Stephen Hawking , who was always skeptical about the idea of time travel into the past, to come up with his "chronology protection conjecture" — the notion that some as-yet-unknown law of physics prevents closed timelike curves from happening. But that conjecture is only an educated guess, and until it is supported by hard evidence, we can come to only one conclusion: Time travel is possible.

A party for time travelers 

Hawking was skeptical about the feasibility of time travel into the past, not because he had disproved it, but because he was bothered by the logical paradoxes it created. In his chronology protection conjecture, he surmised that physicists would eventually discover a flaw in the theory of closed timelike curves that made them impossible. 

In 2009, he came up with an amusing way to test this conjecture. Hawking held a champagne party (shown in his Discovery Channel program), but he only advertised it after it had happened. His reasoning was that, if time machines eventually become practical, someone in the future might read about the party and travel back to attend it. But no one did — Hawking sat through the whole evening on his own. This doesn't prove time travel is impossible, but it does suggest that it never becomes a commonplace occurrence here on Earth.

The arrow of time 

One of the distinctive things about time is that it has a direction — from past to future. A cup of hot coffee left at room temperature always cools down; it never heats up. Your cellphone loses battery charge when you use it; it never gains charge. These are examples of entropy , essentially a measure of the amount of "useless" as opposed to "useful" energy. The entropy of a closed system always increases, and it's the key factor determining the arrow of time.

It turns out that entropy is the only thing that makes a distinction between past and future. In other branches of physics, like relativity or quantum theory, time doesn't have a preferred direction. No one knows where time's arrow comes from. It may be that it only applies to large, complex systems, in which case subatomic particles may not experience the arrow of time.

Time travel paradox 

If it's possible to travel back into the past — even theoretically — it raises a number of brain-twisting paradoxes — such as the grandfather paradox — that even scientists and philosophers find extremely perplexing.

Killing Hitler

A time traveler might decide to go back and kill him in his infancy. If they succeeded, future history books wouldn't even mention Hitler — so what motivation would the time traveler have for going back in time and killing him?

Killing your grandfather

Instead of killing a young Hitler, you might, by accident, kill one of your own ancestors when they were very young. But then you would never be born, so you couldn't travel back in time to kill them, so you would be born after all, and so on … 

A closed loop

Suppose the plans for a time machine suddenly appear from thin air on your desk. You spend a few days building it, then use it to send the plans back to your earlier self. But where did those plans originate? Nowhere — they are just looping round and round in time.

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Andrew May holds a Ph.D. in astrophysics from Manchester University, U.K. For 30 years, he worked in the academic, government and private sectors, before becoming a science writer where he has written for Fortean Times, How It Works, All About Space, BBC Science Focus, among others. He has also written a selection of books including Cosmic Impact and Astrobiology: The Search for Life Elsewhere in the Universe, published by Icon Books.

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Einstein's equation and time travel

How is Einstein's equation (Gμν = 8πG Tμν) actually applied? And how does it support the theory of time travel.

Many physicists refer to this as Einstein’s Equations (plural) because it's actually a set of several equations. The symbol Gμν denotes the "Einstein tensor," which is a measure of how much space-time is curving. The symbol Tμν denotes the "energy momentum tensor," which measures the density and flux of the energy and momentum of matter. The energy and momentum of matter causes space-time to curve in a way that is described by Einstein’s Equations. The curvature of space-time is what causes all the effects that we associate with "gravity."

There are many textbooks that explain how to apply Einstein’s Equations equations to various situations, but they require a very advanced background in physics and mathematics. I will therefore have to summarize things in words.

Before talking about time travel, let me first explain what a "world-line" is. Suppose that an object at a particular time is sitting at some particular point in space. At another time, it will be sitting at another point. Its locations at different times trace out a path through space-time, which is called the object’s world line. This path extends forward to points farther and farther in the future (until the object ceases to exist for some reason, at which point its world-line ends). But imagine that an object’s world-line bends around in a loop, so that at it arrives at a point in space-time where it had already been? For example, there may be a point on my world line that was me at my fifth birthday party at my parents’ home in New York City. Another point (farther along my world-line) is me now, aged 61, sitting in my office at the University of Delaware. If I continue farther and farther along my world line, might I end up again at my fifth birthday party in New York City in 1958? Could my five-year old self meet my much older self at that party? That is what most people mean by "time travel." In the jargon of physics, such a world line that bent around and intersected itself is called a "closed time-like loop" or "closed time-like curve."

The question is whether world-lines that are closed time-like loops are possible in the real world. It is comparatively easy to show that if space-time were not curved world-lines would definitely not be able to bend around to form closed time-like loops. But one might hope that gravity, by curving space-time, could bend some world-lines around to make closed loops. The way people have studied this question is to assume that Einstein’s equations correctly describe how the energy and momentum of matter curves space-time. Then they look for solutions of those equations where space-time curves in such a way as to make closed time-like loops possible, and therefore time-travel possible. No one has ever found such solutions. People have on occasion found what seemed to be such solutions, but on closer inspection it was found that when realistic conditions are imposed, no time travel is possible. An example is the Gödel Universe (or Gödel metric).

One kind of solution that would allow time travel is called a "Minkowski wormhole." A Minkowski wormhole would be like a tunnel that took you from one point in space-time to what seemed like a far distant point--a point far away in space, or in the past, or in the future. But people have shown that for a Minkowski wormhole to exist, there would have to be a type of matter whose energy and momentum were unlike any kind of matter ever seen and extremely unlikely to exist in the real world.

The great majority of experts believe that time travel is not allowed by the laws of physics. But no one has proved that rigorously. If you want to learn more, you could try to find discussions of closed time-like loops and Minkowski wormholes in books or on the internet.

-Stephen Barr

• General relativity

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Time travel: Is it possible?

Science says time travel is possible, but probably not in the way you're thinking.

Albert Einstein's theory

• General relativity and GPS
• Wormhole travel
• Alternate theories

Science fiction

Is time travel possible? Short answer: Yes, and you're doing it right now — hurtling into the future at the impressive rate of one second per second. 

You're pretty much always moving through time at the same speed, whether you're watching paint dry or wishing you had more hours to visit with a friend from out of town. 

But this isn't the kind of time travel that's captivated countless science fiction writers, or spurred a genre so extensive that Wikipedia lists over 400 titles in the category "Movies about Time Travel." In franchises like " Doctor Who ," " Star Trek ," and "Back to the Future" characters climb into some wild vehicle to blast into the past or spin into the future. Once the characters have traveled through time, they grapple with what happens if you change the past or present based on information from the future (which is where time travel stories intersect with the idea of parallel universes or alternate timelines). 

Related: The best sci-fi time machines ever

Although many people are fascinated by the idea of changing the past or seeing the future before it's due, no person has ever demonstrated the kind of back-and-forth time travel seen in science fiction or proposed a method of sending a person through significant periods of time that wouldn't destroy them on the way. And, as physicist Stephen Hawking pointed out in his book " Black Holes and Baby Universes" (Bantam, 1994), "The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future."

Science does support some amount of time-bending, though. For example, physicist Albert Einstein 's theory of special relativity proposes that time is an illusion that moves relative to an observer. An observer traveling near the speed of light will experience time, with all its aftereffects (boredom, aging, etc.) much more slowly than an observer at rest. That's why astronaut Scott Kelly aged ever so slightly less over the course of a year in orbit than his twin brother who stayed here on Earth. 

Related: Controversially, physicist argues that time is real

There are other scientific theories about time travel, including some weird physics that arise around wormholes , black holes and string theory . For the most part, though, time travel remains the domain of an ever-growing array of science fiction books, movies, television shows, comics, video games and more. 

Einstein developed his theory of special relativity in 1905. Along with his later expansion, the theory of general relativity , it has become one of the foundational tenets of modern physics. Special relativity describes the relationship between space and time for objects moving at constant speeds in a straight line. 

The short version of the theory is deceptively simple. First, all things are measured in relation to something else — that is to say, there is no "absolute" frame of reference. Second, the speed of light is constant. It stays the same no matter what, and no matter where it's measured from. And third, nothing can go faster than the speed of light.

From those simple tenets unfolds actual, real-life time travel. An observer traveling at high velocity will experience time at a slower rate than an observer who isn't speeding through space. 

While we don't accelerate humans to near-light-speed, we do send them swinging around the planet at 17,500 mph (28,160 km/h) aboard the International Space Station . Astronaut Scott Kelly was born after his twin brother, and fellow astronaut, Mark Kelly . Scott Kelly spent 520 days in orbit, while Mark logged 54 days in space. The difference in the speed at which they experienced time over the course of their lifetimes has actually widened the age gap between the two men.

"So, where[as] I used to be just 6 minutes older, now I am 6 minutes and 5 milliseconds older," Mark Kelly said in a panel discussion on July 12, 2020, Space.com previously reported . "Now I've got that over his head."

General relativity and GPS time travel

The difference that low earth orbit makes in an astronaut's life span may be negligible — better suited for jokes among siblings than actual life extension or visiting the distant future — but the dilation in time between people on Earth and GPS satellites flying through space does make a difference. 

Read more: Can we stop time?

The Global Positioning System , or GPS, helps us know exactly where we are by communicating with a network of a few dozen satellites positioned in a high Earth orbit. The satellites circle the planet from 12,500 miles (20,100 kilometers) away, moving at 8,700 mph (14,000 km/h). 

According to special relativity, the faster an object moves relative to another object, the slower that first object experiences time. For GPS satellites with atomic clocks, this effect cuts 7 microseconds, or 7 millionths of a second, off each day, according to the American Physical Society publication Physics Central .  

Read more: Could Star Trek's faster-than-light warp drive actually work?

Then, according to general relativity, clocks closer to the center of a large gravitational mass like Earth tick more slowly than those farther away. So, because the GPS satellites are much farther from the center of Earth compared to clocks on the surface, Physics Central added, that adds another 45 microseconds onto the GPS satellite clocks each day. Combined with the negative 7 microseconds from the special relativity calculation, the net result is an added 38 microseconds. 

This means that in order to maintain the accuracy needed to pinpoint your car or phone — or, since the system is run by the U.S. Department of Defense, a military drone — engineers must account for an extra 38 microseconds in each satellite's day. The atomic clocks onboard don’t tick over to the next day until they have run 38 microseconds longer than comparable clocks on Earth.

Given those numbers, it would take more than seven years for the atomic clock in a GPS satellite to un-sync itself from an Earth clock by more than a blink of an eye. (We did the math: If you estimate a blink to last at least 100,000 microseconds, as the Harvard Database of Useful Biological Numbers does, it would take thousands of days for those 38 microsecond shifts to add up.) 

This kind of time travel may seem as negligible as the Kelly brothers' age gap, but given the hyper-accuracy of modern GPS technology, it actually does matter. If it can communicate with the satellites whizzing overhead, your phone can nail down your location in space and time with incredible accuracy. 

Can wormholes take us back in time?

General relativity might also provide scenarios that could allow travelers to go back in time, according to NASA . But the physical reality of those time-travel methods is no piece of cake. 

Wormholes are theoretical "tunnels" through the fabric of space-time that could connect different moments or locations in reality to others. Also known as Einstein-Rosen bridges or white holes, as opposed to black holes, speculation about wormholes abounds. But despite taking up a lot of space (or space-time) in science fiction, no wormholes of any kind have been identified in real life. 

Related: Best time travel movies

"The whole thing is very hypothetical at this point," Stephen Hsu, a professor of theoretical physics at the University of Oregon, told Space.com sister site Live Science . "No one thinks we're going to find a wormhole anytime soon."

Primordial wormholes are predicted to be just 10^-34 inches (10^-33 centimeters) at the tunnel's "mouth". Previously, they were expected to be too unstable for anything to be able to travel through them. However, a study claims that this is not the case, Live Science reported . 

The theory, which suggests that wormholes could work as viable space-time shortcuts, was described by physicist Pascal Koiran. As part of the study, Koiran used the Eddington-Finkelstein metric, as opposed to the Schwarzschild metric which has been used in the majority of previous analyses.

In the past, the path of a particle could not be traced through a hypothetical wormhole. However, using the Eddington-Finkelstein metric, the physicist was able to achieve just that.

Koiran's paper was described in October 2021, in the preprint database arXiv , before being published in the Journal of Modern Physics D.

Alternate time travel theories

While Einstein's theories appear to make time travel difficult, some researchers have proposed other solutions that could allow jumps back and forth in time. These alternate theories share one major flaw: As far as scientists can tell, there's no way a person could survive the kind of gravitational pulling and pushing that each solution requires.

Infinite cylinder theory

Astronomer Frank Tipler proposed a mechanism (sometimes known as a Tipler Cylinder ) where one could take matter that is 10 times the sun's mass, then roll it into a very long, but very dense cylinder. The Anderson Institute , a time travel research organization, described the cylinder as "a black hole that has passed through a spaghetti factory."

After spinning this black hole spaghetti a few billion revolutions per minute, a spaceship nearby — following a very precise spiral around the cylinder — could travel backward in time on a "closed, time-like curve," according to the Anderson Institute. 

The major problem is that in order for the Tipler Cylinder to become reality, the cylinder would need to be infinitely long or be made of some unknown kind of matter. At least for the foreseeable future, endless interstellar pasta is beyond our reach.

Time donuts

Theoretical physicist Amos Ori at the Technion-Israel Institute of Technology in Haifa, Israel, proposed a model for a time machine made out of curved space-time — a donut-shaped vacuum surrounded by a sphere of normal matter.

"The machine is space-time itself," Ori told Live Science . "If we were to create an area with a warp like this in space that would enable time lines to close on themselves, it might enable future generations to return to visit our time."

Amos Ori is a theoretical physicist at the Technion-Israel Institute of Technology in Haifa, Israel. His research interests and publications span the fields of general relativity, black holes, gravitational waves and closed time lines.

There are a few caveats to Ori's time machine. First, visitors to the past wouldn't be able to travel to times earlier than the invention and construction of the time donut. Second, and more importantly, the invention and construction of this machine would depend on our ability to manipulate gravitational fields at will — a feat that may be theoretically possible but is certainly beyond our immediate reach.

Time travel has long occupied a significant place in fiction. Since as early as the "Mahabharata," an ancient Sanskrit epic poem compiled around 400 B.C., humans have dreamed of warping time, Lisa Yaszek, a professor of science fiction studies at the Georgia Institute of Technology in Atlanta, told Live Science .  

Every work of time-travel fiction creates its own version of space-time, glossing over one or more scientific hurdles and paradoxes to achieve its plot requirements. 

Some make a nod to research and physics, like " Interstellar ," a 2014 film directed by Christopher Nolan. In the movie, a character played by Matthew McConaughey spends a few hours on a planet orbiting a supermassive black hole, but because of time dilation, observers on Earth experience those hours as a matter of decades. 

Others take a more whimsical approach, like the "Doctor Who" television series. The series features the Doctor, an extraterrestrial "Time Lord" who travels in a spaceship resembling a blue British police box. "People assume," the Doctor explained in the show, "that time is a strict progression from cause to effect, but actually from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey stuff." 

Long-standing franchises like the "Star Trek" movies and television series, as well as comic universes like DC and Marvel Comics, revisit the idea of time travel over and over. 

Related: Marvel movies in order: chronological & release order

Here is an incomplete (and deeply subjective) list of some influential or notable works of time travel fiction:

Books about time travel:

• Rip Van Winkle (Cornelius S. Van Winkle, 1819) by Washington Irving
• A Christmas Carol (Chapman & Hall, 1843) by Charles Dickens
• The Time Machine (William Heinemann, 1895) by H. G. Wells
• A Connecticut Yankee in King Arthur's Court (Charles L. Webster and Co., 1889) by Mark Twain
• The Restaurant at the End of the Universe (Pan Books, 1980) by Douglas Adams
• A Tale of Time City (Methuen, 1987) by Diana Wynn Jones
• The Outlander series (Delacorte Press, 1991-present) by Diana Gabaldon
• Harry Potter and the Prisoner of Azkaban (Bloomsbury/Scholastic, 1999) by J. K. Rowling
• Thief of Time (Doubleday, 2001) by Terry Pratchett
• The Time Traveler's Wife (MacAdam/Cage, 2003) by Audrey Niffenegger
• All You Need is Kill (Shueisha, 2004) by Hiroshi Sakurazaka

Movies about time travel:

• Planet of the Apes (1968)
• Superman (1978)
• Time Bandits (1981)
• The Terminator (1984)
• Back to the Future series (1985, 1989, 1990)
• Star Trek IV: The Voyage Home (1986)
• Bill & Ted's Excellent Adventure (1989)
• Groundhog Day (1993)
• Galaxy Quest (1999)
• The Butterfly Effect (2004)
• 13 Going on 30 (2004)
• The Lake House (2006)
• Meet the Robinsons (2007)
• Hot Tub Time Machine (2010)
• Midnight in Paris (2011)
• Looper (2012)
• X-Men: Days of Future Past (2014)
• Edge of Tomorrow (2014)
• Interstellar (2014)
• Doctor Strange (2016)
• A Wrinkle in Time (2018)
• The Last Sharknado: It's About Time (2018)
• Avengers: Endgame (2019)
• Tenet (2020)
• Palm Springs (2020)
• Zach Snyder's Justice League (2021)
• The Tomorrow War (2021)

Television about time travel:

• Doctor Who (1963-present)
• The Twilight Zone (1959-1964) (multiple episodes)
• Star Trek (multiple series, multiple episodes)
• Samurai Jack (2001-2004)
• Lost (2004-2010)
• Phil of the Future (2004-2006)
• Steins;Gate (2011)
• Outlander (2014-2023)
• Loki (2021-present)

Games about time travel:

• Chrono Trigger (1995)
• TimeSplitters (2000-2005)
• Kingdom Hearts (2002-2019)
• Prince of Persia: Sands of Time (2003)
• God of War II (2007)
• Ratchet and Clank Future: A Crack In Time (2009)
• Sly Cooper: Thieves in Time (2013)
• Dishonored 2 (2016)
• Titanfall 2 (2016)
• Outer Wilds (2019)

Additional resources

Explore physicist Peter Millington's thoughts about Stephen Hawking's time travel theories at The Conversation . Check out a kid-friendly explanation of real-world time travel from NASA's Space Place . For an overview of time travel in fiction and the collective consciousness, read " Time Travel: A History " (Pantheon, 2016) by James Gleik. 

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Ailsa is a staff writer for How It Works magazine, where she writes science, technology, space, history and environment features. Based in the U.K., she graduated from the University of Stirling with a BA (Hons) journalism degree. Previously, Ailsa has written for Cardiff Times magazine, Psychology Now and numerous science bookazines. 

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