BBC's Doctor Who narrates the stories of the protagonist jumping casually through 'different times' in his ‘time machine'
One of the most exciting human abstractions is the idea of traveling through time, a travel into ‘the Past’ and/or into ‘the Future’ from the ‘Present’. This conjecture has its roots in theology and in myth, in philosophy and in science, in facts and in fiction. It is about a travel ‘of a physical body’ and not of thought. As a matter of fact it is one of those aboriginal ideas of humankind that has evolved from a mere ‘dreamed-desire’ of the soul towards an ‘achievable-impossibility’ of the substance. Apparently it has always excited humankind as long as the known history of this specie goes and is coded in its DNA, in any state of physical or spiritual self.
Ever since the invention of Stone tools (some 2.6 million years ago) to James Webb telescope (to be launched in 2018), since the Wheel (4000 BCE) to the Voyager 2 of NASA (launched in 1977 and is currently traveling through Heliosphere - over 2 Billion Miles from Earth, a Sun-controlled bubble like region of space outside the orbit of Pluto) on its way to Sirius - the brightest visible star in the night sky. This idea, once the most luxurious dream, has been evolving a scientific pathway towards its realization that could (or could not) bring it to a vulgar reality.
The scientific depiction of time travel is a travel of physical body starting a journey from ‘one fixed moment’ of the present towards ‘some other fixed moment’ of the past or the future. To understand it lets elaborate this through the example of air-travel between two different parts of the world but before that a lets refresh the concept of time-zones. The Earth completes a full rotation on its axis within 24 hours, which we call a full day. During this, as the Earth is spinning on its imaginary pole, some parts of it get the Sunlight while some parts on the opposite side are dark. This is day-night divide. When at any location, the Earth is spinning towards Sunlight, you get Sun-rise and as it is spinning against it, you get Sun-set. If the whole Earth had one time-zone, the noon at any given place would be morning or evening or even a dark night at other places. To resolve this situation, scientists divided the Earth into 24 time-zones based on its latitude position to Sun. At any place on Earth when Sun is at 90 degree any place on Earth, they divided the whole 360 degree rotation by 15 degrees intervals to reach back to the same position after 24 hours and therefore 1200 hours is considered noon at all places on Earth while 2400 hours is the mid-night. Coming back to our example of air-flight let us analyze a travel between Lahore and London. The approximate distance between these two points is 5300 miles and airplanes normally travel at a flight speed of 575mph. A flight from Lahore towards London flies for roughly 9 hours in the sky at some 35,000 feet altitude. If time-zones were fixed, a flight taking off at 1100 hours should reach London at 2000 hours but after this time-zone division, the flight lands at 1600 hours. It crosses 4 time zones on its way. This difference of 4 hour is ‘time saving’ while travelling towards west and on the way back, from London to Lahore, towards east it is ‘time-loss’. Due to this we experience 4pm or 1600 hours twice within one day while travelling from east to west but this is not travelling through time. The Earth rotates at the speed of 1000 mph around its axis but the aircraft travels at 575 mph and if aircraft travelled at 1000 mph, the traveler could reach London in 5 hours 20 minutes where the local time would have been 11:40 AM. For a traveler to reach London at 11 AM after flying from Lahore at 11 AM he has a use a machine that travels at 1325 mph. And to reach at exactly at 07:00:01 AM (in one second after leaving Lahore as per its local time of 11:00:00 AM) he has to travel at 1,908,000,000 m/s which is only 0.7% of the speed of light. At speed of Light, he will reach “1.79e-5” seconds behind the original present time of destination. This is what we call time travel.
This is an example to show that the moment a traveler reaches the speed of light, he starts travelling in time and this raises a lot of questions that go beyond the domain of science. Before moving to the scientific dilemma in this regard, let’s briefly go through some other non-scientific claims.
The Philosophical – Fictional Doctrines
Parmenides of Elea, the Pre-Socratic Greek Philosopher, called time an illusion, a non-real entity, this idea was supported by ‘Sir Isaac Newton’ of 18th Century who believed in ‘Absolute Time’ (the fixed nature of events) where time-space were only a stage on which events happen. Leibniz, a contemporary of Sir Isaac Newton, believed time was just a relationship-string between events and not an independently describable entity. Both of these scientists belonged to the ‘Eternalism-Principle’ of existence of universe but with Albert Einstein of 20th century came a ‘theory of relativity’ where time and space were woven into a single continuum to be called time-space, simply denoting that an event that occurs at the one point of time for one observer may occur at a different point of time for another.
‘The Time debate’ between philosophers has a very clear versus scenario; ‘Eternalism’ vs ‘Presentism’. ‘Eternalism’ position is that past, present and future, all exist simultaneously and only the flow of elapsed time reveals what pre-defined future holds. This idea is not consistent with the special or general relativity of time and with Einstein’s ‘Theory of Big-Bang’, where universe is believed to have a beginning, this school lost its scientific backing. With this theory we not only found that the universe began at some point in time (some 13.8 Billion years ago) but with galaxies growing apart, we got the proof that it is still expanding, so the theory of ‘Eternalism of universe’ is completely dropped for further fact findings. Having said that, the common concept of traveling through time is very consistent with ‘Eternalism’ because it allows the time traveler to see the past as well as the future like a recorded movie and as everything is pre-destined, every event of the past or the future is a constant and available to be seen.
On the other hand, although very much aligned with relativity is the philosophy of ‘Presentism’, where ‘the present’ is the only reality and as it is unveiling ‘the future’ with every successive moment, it is also converting itself to become ‘the past’ at the same time. ‘The past’ and ‘the future’ in real time do not exist but the ‘real objects’ do. That is why if someone from future returns back to present, he can see how the past is shaping up the future through processes happening as the Present. This makes time travelling an experiment to see the movement of the cosmos only, not the as the popular films or TV shows (Back to the future – The Flash) like depiction of the events of daily life. Here the problem is ‘space’ element of the ‘time-space’ paradigm. The observations made at ‘a-single-moment-of-present’ from ‘one-point-of-view’ will be always different from ‘any-other-point-of-view’ leading to two different pasts and two different futures. To explain let’s take an example of Mustafa who observes the motion of the cosmos from a point where he is moving away from it, then the observations of Mustafa will be different from those of Murtaza who observed the cosmos coming nearer at the very same moment, so both will give accounts of different pasts and different futures. This makes time travelling even more mind-boggling as we try to depict it via different-point-of-views.
Fiction or literature created to explain time travel majorly supports the ‘dropped’ theory of ‘Eternalism’. Here events of the past or the future are shown as recorded-live events. H.G. Wells in his 1895 novel ‘The Time Machine’ introduced a fantasy-machine through which the protagonist travelled through time and viewed different eras as recorded events. In 1980s came ‘Back to the Future’, a trilogy of films that elaborated this concept of how this was possible and also pointed out some of the outcomes that may occur if this goal in achieved. Some authors used ‘long sleeps’ while others used ‘teleportation devices’ to make humankind able to travel through time. Currently, when we have made a lot of progression with gadgetry on ‘The Flash’, a television program that shows the protagonist achieving the running-speeds to travel through different timelines but here the catch is that he travels in a multiverse model through wormholes.
The Theological – Mythical Doctrines
Time travel has greatly being a subject matter of Theology and Myth. It actually originated here and science, on its way to catching up, has made serious attempts to understand it, but certain limitations of the physical-phenomenon of the time has made it shy away from it.
Among many theologian theories, the most powerful stance on time travel comes from the Islamic Doctrine in the form of Miraaj-e-Nabwi (PBUH). It is a travel of the Prophet (PBUH) from his door to the 7 Heavens and during this the Prophet (PBUH) witnessed some parts of the timeline, the inception of the universe, glimpses of the Day of Judgment and parts of Heaven and Hell. This was a physical journey which makes it a special event, otherwise if it would have been a dream, it would loss its significance. Here the specialty is that the Prophet (PBUH) defined the time as a very small portion spent here on Earth which was equivalent to many years of that journey. Secondly there is a Qur’anic claim the time passes quickly over here than in the Heavens.
Other than this Monumental claim of time travel of Prophet (PBUH) in Islamic tradition there are some more declarations associated with Prophet Adam (PBUH) who is believed to have witnessed where His (PBUH)’s children will end-up as this whole circus of life winds-up.
In the mythology of Mahabharata of Hinduism, King Raivata Kakudmi travelled towards Brahama, but when he returned many ages have passed. Here the claim of time travel is completely opposite that a little time spent in the heavens has been a lot of time on the Earth.
The Pali Canon of Budhism advocates relativity of time through the dialogues of Kumara Kassapa and Payasi. Here the claim being time travels slower in the heavens and lives are longer there again consolidates the Islamic traditional and generally accepted scientific claim of speed of time.
Nihongi which is the part of Urashima Taro, a Japanese tale, also mentions similar kind of phenomenon. This time the time travel is not done through heavens but through deepest of oceans. Here it is claimed that time moves faster in deep oceans than on surface.
Examples like these prove that this idea is not among the novel ones appearing from nowhere but it is among deeply rooted part of subconscious-unconscious thoughts.
The Problems with Time Travel
Since this phenomenon generated so much interest, science clearly defined models to achieve it. Time travelling is a bi-directional travel into the ‘past’ and the ‘future’. In creations of models, at the very initial stages, Physics hit colossal hurdles on both routes. The problems that it identified at the initial stages clearly indicated that this might remain a dream and could never become a reality. Physics based this ‘impossibility’ on number of grounds for both directions.
Travelling to the Past:
We, the humans, see anything on ‘reflection of light principles’. When the light falls on an object it reflects back to our vision and then we are able to witness it, therefore when we actually observe some event, it has already been a past event by the time the light took to reflect it back to us. This is what the Theory of Relativity is. The speed of light is calculated at 299,792,458 miles/second and as our brain cannot break it down to that speed, we translate this occurrence in the real time. This whole thing drastically changes when we are talking about the cosmos. The distances there are so mind-boggling that when we see some cosmic event happening 1 million light years away, we actually mean that it occurred 1 million years ago (as per our time calculation), as it has happened approximately 9,434,828,404,209,600,000,000 miles away and its reflection took 1 Million years to reach us. This principle, on papers, supports time travel and to witness something that happened 24 hours ago, we have to travel 25,902,068,371,200 miles away from Earth (Voyager 2 has just reached just over 2 billion miles away) and with the help of telescopes we can see what actually happened yesterday.
This is all quite convincing and exciting and thoroughly worked out but then it is inevitable to consider its effect in other aspects. If we can witness the events of the past, can we alter them as well? This can be explained through the second problem that science has identified as ‘The Grandfather Paradox’.
In simple terms, this means that if you travel back in time and kill your grandfather even before the birth of your own father, this would break the DNA chain because your father has never been born hence how would you ever get your genetic material in the first place? Say your father was born on 1st January 1968 (roughly 50 years ago), then to be back in time on 1st January 1967 (to make sure he is not even conceived) you have to travel some 481,176,248,614,689,600 miles away, find him at an exact location, eliminate him and travel back; through the ‘relativity principle’ it is a possibility but the bitter question is where will you come back, because to come back to a specific location, you have to be at that location at the first place, but how could you be at some place if you were never born?
This leads us to ‘closed time loops’, it suggest that even if we achieve those distances and somehow develop the tools to travel and witness the past, we might not be able to alter it altogether because the time which has happened in the past has made itself final and closed the loops to enter. We also witnessed this through far distances, where we have reached and looked back towards Earth but couldn’t see the past events happening in the real time even those ‘nanoseconds’ ago. It consolidated that the occurrences of real time are not constants and ‘no foot prints are recorded on the sands of time’. No one is filming it for us to press the rewind button and witness it.
Travelling to the Future:
Now about future, can we go into future and witness the results of our actions? To achieve this even bigger issues arise. One is the assumption that the whole 23-24 Billion years life of our universe has a ‘fixed time loop’, pre-destined. Past is only a way to explain present and all events of present are not happening with a ‘choice’ but only as an ingredient to shape up a already fixed-future. The whole timeline from ‘the Big Bang’ from where it started towards the death of the universe via any of ‘the big crunch’ or ‘the big rip’ or ‘the big chill’ or all of these are acting on a fixed and pre-determined path.
Another issue is about examination of such a thing, theoretically, an object has to travel faster than the speed of light to reach to the points where these events really occur but the observable light has not yet reached yet. Now if certain events have not occurred before to realize ‘that present’ how can they be observed? Even with pre-destination principles, the events, however fixed in their nature, will only occur if all the ingredients leading to it are in place; if anything is missing, the picture will not click.
This negates the very nature of life’s existence, its evolution, its intelligence, its journey of development and its purpose. On the basis of many more paradoxes along with these, Science in general and Physics specifically took a bow down in following this dream.
Finally if ‘the nature of physical laws’ do not permit this achievement, why do humans still have an urge to believe that this could happen?
The answer is laid in a dimension which goes beyond space-time, a point where space-time becomes constant and other dimensions start playing their roles. In that scenario time travel is not only possible but it can be achieved as desired. Science doesn’t deal with these chapters but Theology does. The whole concept of ‘Day of Judgment’ where the acts will be ‘rewarded’ or ‘punished’ clearly indicate that this will happen for everyone, early men evolving to become pseudo-supernatural beings, riding the horses of technology, leaping forward at speeds unimaginable by their predecessors, will one day become a part of those dimensions beyond space-time and revisit the Beginnings and the Ends.