The Scientific Possibilities of Time Travel | Natsuko Yamaguchi | TEDxISPP

so I'm pretty sure we've all seen a science-fiction movie or book about Zach travel at some point in our lives but they'd be back to the future or the famous novel The Time Machine by HG Wells we all loved as a child but have you ever wondered if this is all just fantasy fiction just mere imagination is there possibility in which it could be possible and if so how will affect their work before we dive show them let's make sure they all actually understand what time travel is time travel is basically a discrepancy between time and time it's when the separation of time between departure and arrival does not equal the duration of the journey first thing you have to understand the Einstein's theory of relativity which is a key theory in the idea of time travel there are actually two theories which is the special theory of relativity and the theory of general relativity but basically it states that space and time are into movement into what is known as space-time Einstein concluded the time has changed according to the speed of an object relative to the ephemeral difference for an observer so in the special theory of relativity it stated that the speed of light is constant for all observers traveling at 300,000 kilometers per second and that object moving a constant speed should be subject to the same physical laws now this may sounds very complicated but stay with me so for example if I'm playing catch with my friend and I'm running at 50 miles per hour with a boy it is obvious the relative to me the bull would not be moving until I throw it but relative to my friend who is standing still further away standing still observing me the bull wouldn't be moving at 50 miles per hour as I'm holding and running with it so now let's get to the interesting part how my time travel would be possible the first theoretical method is the wormhole it weren't all connects two months in space through a higher dimension meaning that an object enters from one end of the wormhole would appear at alland almost instantaneously even if the openings are separated by trillions and trillions of miles however scientists know that if wormholes were to exist they would evaporate before anything even light can pass through them and also one was almost likely needed to be artificially created because there are no evidence of them existing naturally as the physicists kept on has stated in his book the science of the interstellar then we see no object in space that could become wormholes as they age he also theorized to make a world with traversable could make traveling through space time using a wormhole possible some form of negative energy will be required in quantum physics this comes in the form of the Casimir energy so what is the Casimir energy the cosmic energy was first predicted in 1948 by a Dutch physicist called Hendrik Casimir it can be observed when two metal plates are faced together in vacuum and some of the vacuum fluctuations will fit in between them bouncing back and forth what others were not as we move the mirrors closer and closer the other the longer waves will no longer be able to fit and therefore it will need that amount of energy in between the plates would be slightly less than anywhere else in the vacuum and considering that amount of energy anywhere else in the vacuum is zero the amount of energy in between the plates will be negative so let's see how this works next so although there are arguments as the wormhole is not existing there are counter argument saying that oh just lowermost do in fact exist continuously winking into and out of existence some have suggested that these can be stabilized and expanded using the Casimir effect by placing two super conductive metals of years in the mouth of the wormholes which will act like the metal plates with a throat of the work more in between this means the locally mass negative region of space-time will be created and that each under the wormhole can be transported somewhere light-years away of course this would mean that the initial trip will have to be taken and normal space-time and therefore would be taken and satellite speeds but if this were to be achieved the chip wouldn't even take the long did the attack of time dilation afterwards instantaneous communication and transport through the wormhole would be possible another idea is using a cosmic string a cosmic string is a hypothetical one dimensional defect left over from the of the universe okay that was a mouthful um it was first theorized where principal sis janitor in 1991 if they were talking if they were to existing have an immense amount of gravitational pull causing flame dragging so the way this will work is that two cosmic strings as they cross paths to each other at very high speeds who work space-time a ship can they take a very precise path and end back at a starting position and this would allow time travel however cosmic chains again have is not found and even God himself stated they ordered traveled just one year back in time it require a loop of string or a lot of energy and by that you wouldn't need half the mass energy of an entire galaxy so another theoretical method is using a bat-pole the way this we work is that a ship renew at very high speed around the buckle experiencing less time than anyone else further away from the black hole and this works because Ibaka has a very strong gravitational field which doesn't even allow light to escape and this causes time dilation the problem here is that the spaceship will have to move in and sublight speed and if a person flies light into the black hole you guys can guess what's gonna happen to them they're gonna get crushed but when you need variety might not which is known as a current level or the current we just first theorized by Roy Carr in 1963 its concept hinges on neutron stars that instead of collapsing on a center or a singularity it'll collapse into rotating Reagan neutron stars and because all the lack of singularity people think they would be safe to enter them without the fear of being crushed by an infinite gravitational force that exists at the center of most black holes and must be travelling to the speed of light may also be a solution when you travel a very high speeds like the speed of light your clock runs slow relative to the people that are not in motion so if I have a spaceship that's traveling at 99.5% the speed of light and observer I'm looking into the spaceship would see the clock inside a spaceship moving to be about ten times slower than normal and me in the spaceship moving in slow motion so here comes mathematics the amount of time dilation can be calculated by the Lorentz factor and I know since not all of you are fan of mathematics I'm just gonna save you from this so when you travel at 25 percent the speed of light you call this the factor is just one point zero three which is about a 3% slowing down in time but when you travel a 99.999 percent the speed of light the factor is two hundred and twenty four experiments have shown this through an old t-shirt with one particle that haven't really travels at about 99.9% of speed of light actually lives and travels up to 2025 times longer and further than is theoretically should but all this talk about traveling in time creates creates what is known as paradoxes so paradoxes are situations in which despite acceptable reasoning these still conclusion with simply self-contradictory one of the most famous time travel paradox is known as a grandfather paradox so consider this you're a time traveler that goes back in time for fascination and the victim turns out to be your grandfather if you pull the trigger and kill your own grandmother what will happen to you if then the then your grandparents wouldn't have happen your parents to have you but there are ways in which these can be overcome the post legend model is one it follows a Novikov self-consistency principle stating that any changes to the timeline cannot be made because any alterations have already been made so whatever happened happened so even rather paradox you would just simply not be able to pull the trigger or even if you cut the gamba malfunction the grandfather would be death proof another way out of these paradoxes is a parallel universe and the multiverse theories it was first published by Hugh Everett the third and the multiverse theory states that our universe is not the only one and that there are many universes that exist in power with one another the parallel universes and that every single outcome of an event occurs at every single part of the universe so in the ground for those paradox the supposed grandfather not being the assassin grandfather because a certain is assassin but back in time he had been transported to another time line but if time travel was to become possible in the future can it have negative side-effects can't it somehow destroy our universe the radical newer conjecture is one idea you can change history so considering there is only one universe history will be changed by one time traveller then immediately changed by another this means that your life will change as all day well this could have positive effects such as going forward in time seeing epidemic diseases and natural disasters and saving lives of millions of people what if it becomes accessible to a wider audience and even if you can't make changes to the timeline but we can only observe the past or the future the rich may go forward in time see technical advances and futuristic inventions and use it for their own advantage people will start challenging the beliefs that we have now whether it's a religion or a hit in just basic history so people will see what we have to predict so it's time travel ethical on simple enough consider this changing even one quarter of a second in time can change everything I'm pretty sure you've all been in those situations where you're walking down the street and some car motorcycle just zips past you and you think if I was walking slightly quicker have you been killed if well if time traveler goes back back in time and even altered even the slightest of events you might have been killed are not the same number all people will probably have been killed but who dies and who lives will be different and if a person who is a relative of Hitler who survived a near miss is killed who'd have had children who died had grandchildren to become parents of Hitler Hitler would never have been born okay I know this sounds extreme but it's not really considering that trillions upon trillions of events would have to be taken in the exact same way for Hitler to be born and if he isn't worth the shoes mangas history of the 20th century we changed so if time travel was to become possible I'll be predestined for chaos I mean even if we try to avoid the negative effects that may come with it it's highly debatable if we can we actually have all the power to control every single aspect of new technology somehow people will start finding a way to use it for the worst regardless all the original intentions of the inventor so time travel would just be a cause of chaos after all this knowledge what do you think how many of you tears do things that this is all just childish imaginations how many of you here thinks that there might be a possibility but but remember as long as time-travel remains undiscovered childish imagination and maybe a little bit of quantum physics may just be the key to building up your very own time machine thank you

Channel: TEDx Talks

Views: 21,011

Keywords: TEDxTalks, English, Cambodia, Science (hard), Science, Time, Travel

Id: pmmMpBVYf6E

Length: 13min 17sec (797 seconds)

Published: Sun Jan 03 2016