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Nature reflects our nature
The face of the clock in front of me tells me that the time is 19:04 , and till now I haven ’ t got any visitors from the future . Haven ’ t you leaped yet ? Oh wait , don ’ t you need a time machine first ? It is generally understood that travelling forward or back in time would require a device- a time machine- to take you there . Time machine research often involves bending space-time so much that timelines turn back upon themselves to form a loop . To accomplish this , time machines are often thought to need an exotic form of matter with so-called ‘ negative energy density ’, which could only exist theoretically . And even though it did exist , no one knows how to use it for good .
But there is a practical approach to go to the future through the means of time dilation . “ The faster you move through space , the slower you move through time .” For this one has to travel at near light velocity or approach to a near neutron star or a black hole for a significant period . This would drastically cause dilation , slowing one ’ s time so much that when the person returns Earth , he would notice Earth ’ s time gone ahead of his . However , this is not regarded as time travelling .
Now , think of it like this , when someone time travels , is it the body or the consciousness that travels through time ? A body travelling through time must not be possible because it would add mass to the destined timeline out of nowhere which is violated by the law of mass-energy conservation . If it were a consciousness that travels through time how is it that you come back without the aid of time machine or how is it that you travel to the time before you were even born ?
Besides the physics problems , time travelling also comes with unique situations like the grandfather paradox . The grandfather paradox is a potential logical problem that would arise if a person were to travel to the past time . The name comes from the idea that if a person travels to a time before their grandfather had children , and kills him , which would make their birth impossible . If the person were never to born , then no one kills the grandfather . So , if time travel is possible , it somehow must avoid such a contradiction .
Another paradox called ‘ The Boot-Strap Paradox ’, or ‘ Predestination Paradox ’ or ‘ Ontological Paradox ’ or best known as ‘ Causal Loop ’ describes an event trapped in a time loop . This especially occurs when the future event is the cause of a past event which in turn is the cause of the future event . Both events then exist in space-time , but their origin cannot be determined . This paradox is presented in movies like ‘ Predestination ’, ‘ Triangle ’, ‘ Primer ’ and ‘ Synchronicity ’.
So here is the thing , if you were to personally ask me if time travelling was possible , my answer would be ‘ No ’. With our current understanding , time travelling causes a lot of contradictions and paradoxes we cannot answer . Maybe the coming generations could be able to remove the contradictions and leap through time ? Stephen Hawking thought the same and So one day , he experimented ( which I think is a genius approach ). He threw a party for time travelers from around the world and only publicized the invitations the next day . Nobody came . And this ends our discussion with the popular Fermi paradox that says , “ If time travel was possible , where are all the visitors from the future ?”
76 Year Book of Environmental Science