The Grandfather Paradox - 60-Second Adventures in Thought (2/6)

[@obbeachbum69]

Oh that handy multiverse. Whenever things get sticky like the cosmological constant, just pull it out, rinse and repeat.

[@VOLKHVORONOVICH]

In line with the Grandfather Paradox is a tale of a man who grew up hating his father. The father did not seem to love his wife and was sometimes unaccountably cruel to her. He beat the boy at times and seemed to have a particular vendetta against the child's budding scientific talent. When he is a young man his mother dies. The father grieves but does not seem surprised-almost as if he knew it was going to happen. The son resolves to avenge his mother, whom he is certain that his father has in some way caused her death. A few years later he plants a bomb in his father's car. When the father turns the key and hears the tell-tale click, he cries out, “Oh, no-he did it today! Might as well get it over with.” The car explodes and the police never discover the culprit. With no interference from his father he is free to pursue his scientific interests with a vengeance. He has a goal now. Discover time travel, go back in time, kill his father (the man he hates more than anything in the whole world) before he can marry his mother and make her life a living hell. And he succeeds! He sends himself on a one-way trip to the past. Locates his father and kills him as he makes his way home from work. The murderer is surprised to see that he has not faded out of existence because he's prevented himself from ever coming into existence in the first place. He sets himself to take his place in his new world. A few years pass. He finds a girl, marries her and settles down. Their first child is born and he congratulates himself for changing history, and triumphing over fate. A victory short lived when he sees the reflection of his face in the glass of the maternity ward as he is gazing upon his new born son-it is the face of his father. He has gone back in time and become his own father! He has not changed time-he has only caused it to happen. The man he killed was not his father, but someone completely innocent. He cannot bring himself to touch his wife any more. And he sees the interests of his son veering toward the scientific. He knows the boy will eventually invent time travel. He tries to stop this, smashing radios and television the boy creates. He knows it is fruitless but he can't stop from trying. He is not surprised when he finds out his neglect has killed his wife. He knows his son will blame him for her death. He knows his son will now be actively planning his own death-and there is not a single thing he can do about it, because everything has already been done. The script has already been written and he can't change it. So when he hears the fatal click as he turns the key, though he cries out with fear of what he knows will happen, he knows he has no other choice. “Might as well get it over with.” [This story first appeared in one of the old Warren Magazines probably from the 70s, possibly Vampirella, and in my opinion was friggin' brilliant!]

[@holdupsomethingaintright7919]

I know I'm a bit late for about 4 years but I have to say this short story is mind numbing and amazing holy moly, really goes to show the existential crisis that will emerge if you have somehow caused a grandfather paradox

[@davewilliam5228]

How To Travel Back In Time 1. Make digital clock five hours backwards.

[@davewilliam5228]

How To Travel Back In Time 1. Build circulating light beams machine. 2. Use circulating light beams machine to travel to year 1985AD.

[@Drakus79]

Traveling back in time should be defined simply as traveling to an alternate universe in which all events that took place in history occurred exactly the same way up to the moment you arrived in the past. As soon as you arrive in the past, events unfold differently due to the butterfly effect. You wouldn't disappear if you caused a grandfather paradox because that's not your grandfather. He's a different person on a different timeline with a different future. The timeline you came from is separate from this new timeline you live on and your existence is not dependent on how events unfold on this new timeline. Grandfather paradox solved ... I think.

[@dalinsixtus7648]

James Murray I think it's different My answer is completely different I guess that if you go back and kill you grandfather then an alternative timeline is created and you are stuck there in this new timeline and if you can't travel back to time from where you came. Or it is also possible as shown in some movies that if you go back and kill your grandfather you along with your grandfather will be dead. You will kill your grandfather and it will result in your death coz since he wasn't born then you can't be alive so along with grandfather you will also die creating a new timeline Edit: I'm just 15 so it can be just theory:😂😂😂😂 just laugh it off

[@Drakus79]

@@dalinsixtus7648 A lot of people agree with the single timeline theory, in fact most fiction uses that time travel theory. But there are too many logical inconsistencies for it to be possible. For example, in Back to the Future (spoilers) when Marty goes back in time and accidentally prevents his parents from getting together and giving birth to him he starts to slowly disappear from reality. He does manage to "fix" the timeline and get his parents together in the end, but when he goes back to the future, his parents are very different from how he remembers them due to the changes he made in the past. But why would he have no memory of those changes if they were the same parents that gave birth to him? The BttF trilogy has a lot of logical fallacies that are too long to list, but primarily it's because it accepts the grandfather paradox as possible when there are too many nonsensical things that would happen if there was such a thing. And that's not the only problem with the single timeline theory. For example in Babylon 5 (spoilers), Sinclair goes back in time a thousand years and brings with him an object called the triluminary. This object gets passed down for generations until the present when it's given to Sinclair and he in turn brings it back in time and again it gets passed down for another thousand years. That object has no origin. It exists in an infinite time-loop. How could it exist if it's never been created, and how could it last for so long? Now some people have justified this by saying it's a supernatural object, but the same is true of the compass in the tv show Lost. Richard Alpert gives John Locke a compass. John Locke travels back in time and gives that same compass to a younger Richard Alpert. Richard Alpert grows up and gives that same compass to John Locke who in turn travels back in time and gives that same compass to a younger Richard Alpert. Like the triluminary, that compass also winds up in an infinite timeloop and has no origin. Things like that make for interesting story-telling, but in real life it's impossible. Multiverse time travel makes a lot more sense than single timeline time travel. Marty doesn't have to have the same memories because time traveling Marty is a different person than the Marty born after he went back in time. And objects can't get stuck in time loops because there is no loop. Each timeline is a separate universe. And the idea of a multiverse is something that many physicists agree with so it seems the most plausible.

[@5minshandcraft123]

Then you are not even in your past man!

[@Drakus79]

@@5minshandcraft123 true, it was your past until you went back changed it.

[@davewilliam5228]

How To Travel Back In Time 1. Make Year 1999 calendar. 2. Buy year 1999 clothes and wear 1999 clothes. 3. Buy year 1999 technology and have year 1999 technology.

[@kookookachu26]

This goes into something called the bootstrap paradox. Where you cause event A which causes event B which causes event C which causes event A. Basically, he wouldn't be able to kill his grandfather since time is an endless loop and anomilies such as this one don't have an origin thus pulling himself up by his boot straps.

[@Unknown-sg4tv]

Time Travel Rules short version 1. Only observe don't change history.🍐 2. Wear clothes from that time period.🕵 3. Only spend 1 minute in the past.🕵🕓 For those who want to time travel.

[@Unknown-sg4tv]

Time Travel Rules 1. Only observe don't change history.🍐 2. Wear clothes from that time period.🕵 3. Only spend 1 minute in the past.🕵🕓 4. Find a hide out. So the time machine doesn't fall into the wrong hand's.🚇🐨 5. If history is changed by mistake go back and change it back.🕵🚀🕵 6. No time business only have one time machine.🚀

[@dhvsheabdh]

A difficult question. While some may say "obviously not", others may disagree. Einstein said that as long as the events are not linked causally, then there can be a change of opinion of when it actually happened, as observed by a high speed observer, and a stationary observer, both relative to the observed object.

[@MHGenesis]

I don't see why it's a paradoxon. If you travel back in time, you have already changed the past, so what's happening from that point on, will be entirely different anyway. Because even if you would kill your grandfather, then why should there be something happening to you? The atoms that you consist of, would still be there, you would just change the world that you are currently in. So you basically would create another universe or an alternate line of events in the universe. In general, travelling back in time would change everything, because, if it's true that quantum mechanics are based on probabilities, the events after travelling back in time, would need to be determined again. So if the outcome of quantum events are really "random", there would be a lot of different stuff happening. I think it would be stupid to assume that what happens in your life during the current time, would already be the cause of what you did after travelling back in time, it doesn't make sense at all. Not to forget that it's probably not possible to go back in time. It's just logical, it wouldn't need a parallel universe, it would just change the current universe.

[@ImUnsn]

***** havent thought about it like that.

[@jvincent6548]

Everybody misses the glaringly obvious: WHy would you want to kill anyone least of all a grandfather ? Isn't this a nihilistic ?

[@LeeAnnGlenn]

@@jvincent6548 Could also be that you're the cause of your grandfathers death

[@blkgardner]

The alternate timeline solution in effect assumes the existence of multiple identical universes which are offset in time. Either these multiple universes already exist, or the time travel creates a new universe. In such a case, "time travel" is really travel to a parallel universe. Anything done in the alternate timeline does not affect this universe. A better solution is the idea that time travel can't change the past. Whatever the time traveler does in the past already happened. This means that if you go back in time to change history, you will fail in your endeavor, and quite possibly cause what you are trying to prevent. However, this also means that the time traveler can't hurt the timeline either. For example, the time traveler could have anachronistic conversations with historical figures.

[@QuantumDice]

There is two ways to see time travel 1- Only one time line ( nothing can be changed) 2- Parallel universes If we think of the first possibility it is mind bugling. Let's say that your future self comes from the future to tell you how to build the very time machine he came from. There is no paradox in this situation, the only thing that it imply is that there is no free will.

[@manfreako]

Time travel is currently possible within a 24 hr radius in some form. all you need to do is go through the time zones backwards or forwards.

[@CookinginRussia]

Much simpler solution. You don't LEAP back in time. You GO back in time. So the very first second you actually go back in time is the moment before you went back in time, and thus you would still be going forward in time. You would be stuck in an infinite loop at the present moment you went back in time. There - no paradox.

[@blackhellbeats8221]

everyone? or just you? does anyone even notice? or does time just stop for you untill time machine needs to be refueled

[@CookinginRussia]

Black Hell Beats From the point of view of everyone else, the subject simply disappears, having been left behind in time forever. No additional energy source is required.

[@blackhellbeats8221]

CookinginRussia everything we have uses energy. every appliance hardly anything mjechanical is used anymore..so a time machine.would 99.999% likely run using an extra energy source. im assuingm more thn regular 220 volt also soo eventually it would run out. then the subject could just move on

[@CookinginRussia]

Black Hell Beats No, you don't understand. The time machine also goes back in time to before it spent the energy. It is self-sustaining, but frozen in that moment in time.

[@blackhellbeats8221]

ahh i guess...

[@nicelittlestyleslad]

I don't think you would be able to prevent yourself from being born as it is a certainty. I also think that everything you do in the past will contribute to the future you are from. You would only be able to affect your uncertainties - say you don't know how one of your great-grandparents died, you could be the one who accidentally killed them. If you did actually kill your paternal grandfather before your father was born, then that was what already happened and you just didn't know that. Your paternal grandmother could have secretly adopted your father or your grandfather's sperm was used after he died. This happens in the show Supernatural when Dean tries to change history that occurred before he was born but he finds out that HE was the one who set said events in motion (pretty much) and indirectly killed his maternal grandparents who he had not known existed.

[@thlkl4e]

Time travel in this case would mean "transport" the particles that constitutes your body to the past. So you would be already altering the past as you travel backwards, since all events related to those particles would also change. You'd be isolating those particles from cause and effect events as history is being altered. In a sense, when you land in the past, you're no longer the result of your parents, but the aglomeration of those particles in another timeline, fully formed and with knowledge of your own timeline, that no longer exists. It would be possible that your grandfather no longer exists, since events related to these partcles you're moving through time could also be related to his existence in the past. But assuming he still exists, and your parents still are born, their child could have all your traits but no longer be you! Let's say you eat an apple and want to travel back immediately to eat that again. Either that apple no longer exists or the particles that constituted the apple you ate aren't present in the apple you'll find in the past. In short, you'll never be able to eat the same apple twice. It might have the same shape, smell, taste, but ain't the same. The problem with the paradox is to assume time as an entity separated from space. Time travel is impossible because time, in this sense, doesn't even exist! You can't rewind reality as if had a timescale, what you actually would be doing is to undo cause and effect events to return reality to its previous states while isolating the particles that constitutes you from the process. It's more like erasing the present than going to the past.

[@goat48jimmiejohnson]

Thiago Correia If you're talking about the video, the only thing wrong with it is your interpretation of it. You're creating variables that are completely irrelevant to the point that's being made, and might I add - none of which you actually are certain of, but only speculating about. After all, this is theory and philosophy, not science or fact.

[@OpenLearn_OU]

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[@doltBmB]

Novikov has solved the problem, by the way (together with Kip Thorne, creator of Interstellar, the movie was originally going to touch on the subject but Nolan had other, more pretentious ideas) all grandfather "paradoxes" have an infinite number of non-paradoxical solutions, one of which will always be the case. In other words, it's mathematically self resolving.

[@HallucinogenX]

I like the harmonic universe hypothesis which was kind of stated by HG Wells in his book The Time Machine and it's film adaptation with Guy Pearce.Basically the universe will prevent a paradox from occurring.Like when you travel really really fast(near the speed of light),time actually slows down.Similarly if you try to change something in the past that would nullify your reason to go back in the past,you won't be able to do so.In the movie,Guy goes back in time to save his girlfriend but she is killed in a different manner each time because she has to die.So i assume if you try to kill your grandfather,he will survive somehow.Maybe your gun will get jammed or maybe you'll always miss.

[@QuantumDice]

No, in the "one timeline" hypothesis he doesn't change anything, it's always been like that. Exactly ! You (present) will build that time machine exactly has your future self told you and you will go back in time and tell yourself to build the time machine in the exact same way that you've been told. It's an infinite loop that got no beginning or end.

[@ASSHOLELA]

Normally, we should see product particles, such as a electron and antielectron, from an inteaction of a source particle, such as a photon giving up its energy. But since the space time geometry of quantum foam is irregular, containing wormholes into the past, it could be likeley that a particle from now travelled into the past, interacted with the photon, causing it to vanish, and then we observe that the product electrons appearing from nowhere.

[@goat48jimmiejohnson]

Q: What would happen if you went back in time and _did not_ kill your grandfather, but instead, you stayed on some remote island and eliminated all possibility to change anything - what then? A: Everything unfolds as it did the first time, and eventually your mother is giving birth to a baby which would later grow up to be a second you. This is proof that the grandfather paradox is actually a faulty concept. You cannot go back and prevent your own existence; You can only go back and prevent a second you from existing. From the observer's point of view, which is assumed to be the same as your own perspective, your existence proceeded forward the entire time, as would be indicated by any watch you happened to be wearing. Your iPod would still contain the same songs, and you'd still be wearing the same apparel even if you go back in time to a point before these items were invented. What are people thinking - if you prevent Levi Strauss from being being born that their jeans are going to suddenly disappear? lol No, you can't prevent creation once it's done, you can only prevent it from being created a second time.

[@ASSHOLELA]

youre thinking deterministically. in the quantum world, a cause X will not always lead to a consequece Y. for example, if a nucleus decays neutrons may not always be emitted.

[@jtmichaelson]

Presenter: David Mitchell

[@JokerScribe]

...and then he finds out who his real grandfather was. Clue: he killed his grandmother's husband, but not his dad's father.

[@lcbreezyl]

I always had this question but a little different. What if you went back in time and meet yourself as a kid? You would have already meet yourself and known that you were going to travel back in time when you get to a certain point in your life.

[@LavaCanyon]

No matter what you do you couldn't really avoid creating a paradox. The smallest thing would change what the new timeline version of you would do which would eventually also go back in time and slightly change the 3rd timeline version of you and then he'd also go back in time to change a small thing. That would be happening an infinite number of times as long as the versions of you keep on using the time machine.

[@leviticusrich5909]

For a multiverse theory, how would a grandfather paradox prevail?

[@johnnytluxury]

indeed, every nano variation creates a complete alternate timeline, therefore a new multiverse. You can kill your grandfather because a new universe is created within.

[@Tletna]

The problem with this is that one can only see this one of two ways: Either you failed to kill your grand father (either due to failure to time travel properly or to the same dimension/time and space, remember if you forget to travel *also in space* you'll be stranded in vacuum), or you succeeded but either he wasn't really your grand father and you'll be born another way -or- you from the past no longer can exist, but this doesn't make you killing your grand father impossible, it makes your future time travel impossible... meaning this *is* an alternate reality now. It doesn't necessarily demand parallel realities or universes though. It could be either that all possibilities all exist at once and we can only perceive one at a time or that the old universe collapses the moment you try to create the paradox. The problem with all these views is that they limit the situation to one time traveler when there could be many.

[@Russdogg26]

I also agree I feel like it would branch off another timeline but time travels in a straight line so How does that work out guys??? Let's here some opinions.

[@homingpigeonraces]

time goes as far back as it does forward, so your always in the middle, and it can flow as fast or slow as it wishes, because your always in the middle regardless. Of course there are SET tides, like tides, moons, days, solar years and so on. These cannot be changed, for they are fixed.

[@Myrdin90]

What is your problem? "Anything" is everything you can imagine and/or can't imagine. "Far enough" kinda depends on what you would want the outcome to be i guess, but the furter back in time you would go, the bigger the chance of something really unecspected to happen.

[@Blay007]

Think of time as an infinite string moving horizontally. The string represents all the events and experiences that have taken place and will take place. Now this is just my theory: If a force(time traveler) were to mess with a specific event in history, the string would separate into 2 main strings, and 1 of the 2 main strings would separate into countless small strings, each with the intention of reconnecting to the other main string.

[@RohithBasu]

you can speed up forwards in time by approaching the speed of light :)

[@certaintranquility]

Time dilation causes time to move slower for the person, not faster. Though, it may only seem like 'time travel' to everyone else.

[@QuantumDice]

It is theoretically possible according to Einstein theory of general relativity. We are only talking about the logical implications of it. Travelling to the future is really easy you just need to go fast relatively to something. Example : the astronaut travel faster to the future than us when they are in orbit but by only a very small factor something like 0.000000000000000001 sec. Travelling to the past is a bit more complicated...

[@ASSHOLELA]

In fact, the so called LAWS of physics, are simply there to explain the CORRELATION, ie to relate stuff that happens. And even they are not right 100% of the time.If so we can predict determinstically every event in time. There is this thing called UNCERTAINTY PRINCIPLE in Quantum Mechanics that says that we cant predict everything precisely using the laws of physics. You can only predict the probability of events.

[@ASSHOLELA]

The grandfather paradox becomes a mere triviality if we simply forget one assumption: Correlation is not Causation. We can picture time as a movie, of which we are watching the series of frames. Now lets explore an example. Everytime before you see rain, you see dark clouds in the sky. You see it so many times that eventually you THINK that dark clouds CAUSE RAIN. But they can also be COINCIDENTAL. Everytime there is rain, a dark cloud is always there.

[@mannyjay2027]

imagine that once you and the machine have exited the original timeline you immediately do not exist any longer. yes though none of the events occur resulting in the "leap" including your existance or the research and construction of the machine, the theory proves itself because both you and the machine consistantly do not exist in this theory.there are a few holes in it but i like this theory most

[@RedDwarff]

I would propose it is not possible with the physical body.I also find it really difficult to get my head around time travel possibility.Perhaps into the past as the energy used could somehow be re-established but not into the future ,,,surely, as it hasnt happened yet ?

[@rfvtgbzhn]

Doe anyone know an explaination why the grandfather paradox cannot be eliminated when using parallel universes? It seems kind of illogical to me: if you create a parallel universe by killing your grandfather, this parallel universe has a different spacetime from this point in time, so the death of your grandfather only affects the parallel universe, so the paradox should not exist if you assume that killing your grandfather nefore your parents are born creates a parallel universe.

[@SiddiqueSukdiki]

Even with the idea of travelling back in time, the "past' would as if change in that sense anyway. so you can't go back in time to the same past you heard about because that's not what happened then..

[@ShiroKage009]

@gta4sergio Actually, the brain recognizes it but filters it out as it is, for the majority of cases, is the more efficient method of understanding the communication coming through the medium without the noise caused by "Oh I wonder what the other "the" was meant to do?!"

[@24willa]

watched a video in physics class last friday and the dude in video mentioned the grandfather paradox, and the subject of the video was black hole, white hole and wormholes

[@dynagravitomagnetic]

Bending a local gravity field is the key to time travel. This is not really very difficult, but it is quite expensive and consumes vast amounts of resource. Using a copper torus filled with a working fluid primarily consisting of liquid metal mercury, and a dissolved iron component and using a poly phase induction system to rotate it creates a marconi vortex dynamo. John Titor apparent;y used a solid state version built by G.E. in 3036. Time travel is EXTREMELY DANGEROUS.

[@ojon12389]

I believe in parallel universes. If we truly only had one timeline, then in theory, the grandfather paradox should be impossible to occur. Some people have said that some force would prevent you from killing your grandparent. Maybe, but I find it more believable that the sheer power of time travel would get you to the right time, but a random universe. Hence, the freedom to kill your GP and branch a new timeline. It just seems silly that a universe would explode from one paradox.

[@Radblur]

Is it a paradox or logical impossibility to inquire into what happened before the beginning of time? If time had a beginning, after all, then there must be a 'before' time. Which, at the same time, doesn't make sense within our current frameworks of understanding time. The only thing that is shown by the Grandfather Paradox, other Time Travel Paradoxes, and inquiries into before the start of time, is that we have no idea what time is. Maybe we can't know. Like the incapability of a 2-dimensional drawing to comprehend what is happening when the paper it is drawn on is folded.

[@Shyhalu]

Its logical, if you take into account that time can start and end repeatedly. Before time was simply another 4D instance of what we have now. Imagine a balloon expanding and contracting constantly, something like that.

[@Acheronvampire]

But we all travel forward in time, slowly. To travel quickly forward in time would utilize perspective, therefore "cryogenically" freezing yourself to preserve yourself for the future.

[@Cyclist0623]

Well, for another (utterly) crazy interpretation, you could posit that travel back in time actually does happen all the time. People rub themselves out of existence, and of course hundreds, thousands, or more people along with them (depending on how far back they go), by going back to kill a direct ancestor. Then, neither the ancestor or the killer (nor all the others) exists, and no one is ever the wiser. It explains all the (infinite number of) possible people who AREN'T here!

[@frederickw5532]

As I have posted on other sites, until the problem of particle transportation is resolved grandad will only be a hologram, and you can't kill a hologram

[@chrysafinE97]

Does any one know where the video with all the paradoxes together is?? I can't find anywhere

[@OpenLearn_OU]

Chrysa Mode Hi, the playlist is here - kzbin.info/aero/PL73A886F2DD959FF1 Best wishes, OpenLearn Moderator

[@chrysafinE97]

Thanks!!these videos are awesome

[@yunusemrebalci2201]

r

[@MrTh1rteen]

@youwatch2muchtv No, not necessarily. You'd be bringing it with you from another point of origin. You may create a new branch on the timeline and a new dimension, though you'd still be from that same point of origin.

[@youwatch2muchtv]

@MrTh1rteen How could we go back in time? I mean, if we were to go back in time before a Time traveling device was created, wouldn't that create a singularity, or a paradox right then and there?

[@Waaqawaaqa]

Well, what if you just wanted to do something pointless like move a rock.Would this still apply? I know it's a stupid question but it's the only way I can figure this out.

[@MrMattWelcome]

*Einstein* seems to have only _assumed_ 'time' exists in 'On the electrodynamics of moving bodies' (special relativity). - If in fact - as we directly observe - matter just exists and changes 'now' (so to speak) , then this video > Answers to Brian Cox's Science of Dr Who: (or in more concise form here >Timelessness, Downstairs at the Kings Head London (rt) ) May be more realistic descriptions and solutions to *time travel 'paradoxes'*, such as *the grandfather paradox*, becasue, they demonstrate how *'wormholes' etc may *distort space*, and distort *rates of change* - but not necessarily *'the flow of a thing called time", (unless times existence has _actually been proven_ to at least some degree, as opposed to just being _assumed to exist_). m.marsden ( abh timelessness)

[@oooodaxteroooo]

how did they say in k-pax: "you beings are eons away from discovering light-travel. if you did, youd probably harm yourself or worse - others." (beautiful movie with kevin spacey btw.

[@InfinityEdge9000]

Traveling into the future is possible. Its just takes a while. But theoretically we will be able to do it in the future.

[@AMC2283]

even if you did, I don't think you'd just vanish. you've manipulated space time and now you live in the past. killing what you think of as your past self won't change that.

[@AMC2283]

there are other universes, but it's not like in sci fi with different earth histories--they're just places with different laws of physics

[@HIRVIism]

Are you talking about space-time distortions or something else completely?

[@raashiljain3796]

great overview of basic theories

[@CTCCoco]

This paradox it´s not a problem if there are infinite universes. So, if you travel to the past it´ll be another universe different than yours, because your universe is unique and you can´t travel to the same universe back. Then, all these paradox are solved, you can do whathever you want in a different universe.

[@alfanindayishimiye8362]

At the end of the video it says you may go forward in time to kill future you, I presume. Does that mean the grandfather paradox is broken with your future grandchildren where they are just never born because you have killed future you, i.e their granddad and it remains like that, making time travel possible without a ripple effect.

[@skullbuttery1561]

Wait wouldn't this, when you think about it, apply to most of time travel because if you use time travel to change the past in any way, shape or form, then you've altered the timeline, giving you no reason to change the past in the first place therefore the original timeline is restored and nothing happens or your stuck in an infinite loop. feel free to share your thoughts on my idea.

[@timothypecenka7857]

Too much thinking

[@Tespri]

Yeap it would cause eternal loop. However as all paradoxes, they all have premises which are impossible by default. This would just mean that time travel itself is impossible. Only way you could avoid the loop, is by somehow giving information to your future self that he must go back in time and do X thing and then send this same message to himself in future.

[@alfanindayishimiye8362]

Tespri seems you just end up creating a new loop in the sending of the letter

[@Tespri]

AlfanTheGreat - Not really if the letter itself states that the you in the past has to send letter too. Hence loop would disappear.

[@MrNikolidas]

David Mitchell makes a perfect voice-over artist for this.

[@The1127H]

The boy is born, kills his grandfather, and ceases to exist. At that point a whole new lineage of time springs into existence where the grandfather is killed, and the original keeps moving on as if nothing had happened. Killing his grandfather creates an alternate future that coexist with the first.

[@DraKonfilms]

The Reson that people can't go back in time to say we invented time travel is because it would interfere with the time line and there would be no time travel or send the creation back along time. Make sence?

[@jylcarson8367]

The Grandfather paradox: I disagree.Grandson from 2016 goes to kill grandfather in 1912.The grandfather will only live until the grandson kills him, which will then zap the grandson out from existence on the same date and time the grandson kills his grandfather. He dies 1912.I think there's no point in saying that "there will be no grandson to go back in time to kill the grandfather", because that would mean that time is in a loop, which I think it's not. I think it's pretty linear. An instance of a future may happen once, but once it's altered it will just change forever: both the grandfather and the grandson will cease to exist in 1912.

[@cbr125rcanada]

We're already going forward in time: Just at a measured, steady rate.

[@lazerdemowolf]

@TheDrAZoisberg but the effect of the time modification would only be in effect after you did it. Like young me would to go forward in time to kill old me it would be possible but then when young me grows old to become old me then I would be killed by young me and that young me will grow old and be killed by young me again.

[@Alejandro-Te]

0:20 "What happened if a man went back in time to the day before his father was born and killed his grandfather"?¿?¿?You mean, to the day before his father was conceived, no?

[@SomeGuyWhoPlaysGames333]

If space is really infinite, then it seems like alternate realities could exist. Even if the time traveller is never born and his actions erased, he still killed his grandfather. So not only should his grandfather remain dead, but the time traveller should just disappear from existence.

[@RobertFreemantle]

There's only one way we'll find out and that's to do it! Any takers?

[@QuantumDice]

Exactly! In the one time line hypothesis it's how it would work.

[@88232964G]

You say that like it is fact. That is a theory suggesting time is the 4th dimension. There are other theories suggesting otherwise. It could be possible that time is an illusion that comes about with the existence of a conscience. However you may be right, but we are not certain

[@keithmillar1477]

In the parallel universe idea, there still would've been nobody to kill the grandfather, unless the other one traveled to a different universe, in which case the other version wouldn't exist because he traveled to a different realm and never grew up, so then you would've never even started the whole thing again, and another paradox begins.

[@musicizair1188]

In my opinion and bare with me, In order to travel in time you would need to find a way to suspend your self in a bubble or separate yourself from the current flow of time. Traveling back to kill your grandfather would not be possible as you would only be able to spectate and that's if time is moving which i think would be still. If there was a way to interact with and change events then you would be rewriting your own history from the moment you re-inhabited that space in time, I can't see any way for their to be two of the same person it would be more like your current brain wave patterns moving from your current state to your previous state of being. So if you were to kill your own grandfather it would not be at a point before you were born and history would change and reform from that point. If you were to travel back to the point in time you first left from after such an act you would be leaving your previous self with lost bits of absence that they could not explain and that version of you would continue to rewrite your history therefore changing your memories upon return.

[@goat48jimmiejohnson]

musicizair You're attempting to change the nature of of the paradox by adding variables you're not even sure exist. The only variables are the ones presented - that you travel back and affect the potential of your own existence. But just so you know: 1. You don't have to separate yourself from current flow, so you're not limited only to spectating. 2. You would not be rewriting any history, because according to the calendar of your existence, your own clock is moving forward regardless of what date the rest of the world occupies. 3. There's no evidence that any brain waves or memories would be affected. It's really not as complicated as people make it out to be, but rather so simple that even those who dreamed up this ridiculous paradox missed it. The simplest way to understand what would happen was right there in front of their stupid faces all the time: Q: What would happen if you went back in time and _did not_ kill your grandfather, but instead, you stayed on some remote island and eliminated all possibility to change anything - what then? A: Everything unfolds as it did the first time, and eventually your mother is giving birth to a baby which would later grow up to be a second you. The grandfather paradox is actually a faulty concept. You cannot go back and prevent your own existence; You can only go back and prevent a second you from existing. From the observer's point of view, which is assumed to be the same as your own perspective, your existence proceeded forward the entire time, as would be indicated by any watch you happened to be wearing. Your iPod would still contain the same songs, and you'd still be wearing the same apparel even if you go back in time to a point before these items were invented. What are people thinking - if you prevent Levi Strauss from being being born that their jeans are going to suddenly disappear? lol No, you can't prevent creation once it's done, you can only prevent it from being created a second time.

[@InternetVariationGuy]

Traveling to the future is already a paradox in itself

[@SebbyNilsen]

If I went back in time and killed my grandfather before my mother were born, I would still exist and it wouldn't be any paradoxes. I would just be a different version of myself. Do you know how it's possible?

[@kermitmontz1139]

Why do we limit ourselves to such things? Nothings impossible until its throughly proven as such. Time travel and parellel universes having NOT been proven impossible, are as such still possible!

[@Dhragonfly]

to go backwards in time, is to go fforward in time

[@VOLKHVORONOVICH]

There are a number of flaws in this paradox, the first being that time is a linear, vertical line and that it is the only line that exists. If this was true the man might go back in time, but would never be able to kill his grandfather. No matter how he wanted to (why he would want to is another issue entirely-there are simpler ways to commit suicide, although it would be nice to have a functioning time machine as a consolation prize for the survivors). The parallel worlds hypothesis seeks to answer that by theorizing that each and every action also creates alternate actions and that there exists a world where each of those actions have been followed. For instance, in our world a man comes to a fork in the road and chooses the left hand path. But in the parallel universe he chooses the right hand path. What this hypothesis never takes into account is WHY the man would choose a different road when in our world he chooses the left. Whim? Every decision is based on a solid reason (even if that reason is at times so vague and tentative as to be virtually unconscious. If everything in the alternate world is the same as the original then the man could not make a different choice than he has in the original. Take the example of John Wilkes Booth assinating Abraham Lincoln. He was resolved. Should we believe that an alternate history was created where he changed his mind? Why would he change his mind, every factor being the same as in our world. He himself is the same man-he would have no reason to act differently in the other world if he didn't act differently in this one. He would have to be a completely different person. But what if a security guard in the theatre came upon him and stopped him? Well, why is that guard there in the alternate and why was he not there in our world? You see, if every factor is completely identical there would be no variation. The idea seems to be that in the moment of choice a completely new universe is generated. The problem with that is...where would all the matter and energy to make this new universe instantly come from? Even God took six days to create the universe we live in. But if these alternate universes already existed... If there were an infinite number of universes absolutely identical to one another, like an infinite number of copies of the original document, then it might be possible to move from one of them to another, and affect a change in that one. Thus, it might be possible for Pierre (who hates the man his grandfather was) to go back in time, kill the man and not vanish out of existence-but the grandfather he killed would not be his own, but the grandfather of the Pierre in another parallel. He would be unable to kill the one from his own universe. But if every single Pierre in every single parallel universe is identical then they would all be going back in time and killing the grandfather of an alternate Pierre. It would be impossible. Unless, something from outside the parallel universes acted on a single one of these parallels. Then, and only then could it be possible. But what is it that would exist outside the universes? That is the question.

[@MySerpentine]

This is a very scary thought, and could possibly stop time.

[@Cyclist0623]

A better explanation for why time travel backward is in fact all but certainly impossible, beside all the paradoxes such as the "grandfather problem," not to mention the complete screwing up of cause and effect which would, if it were happening, negate the existence of the universe in which we live (!!), is the fact that it is never observed. If anyone at any time in the future, the infinite future if there is one, ever figured out a way to return in time, we would see returnees to our present.

[@coolboycoolinAtoZ247]

That time alter defense is horrible, the man would have to be alive to shoot his grandfather in the past, so that the second timeline still can't end, the world would have just been taken over by a black whole, or the universe would end the moment it was on the mind to kill your grandfather...I think... Will it? That second timeline would be impossible because then...then... (C'mon, think!)... The events of you shooting your father would still have to happen by perhaps a second watchful other time traveler... So if he sees that, then there would be no way of telling what happen... Or maybe there will? It could happen again, but it can't, so that just goes back to the grandfather paradox... You cannot alter that, you know it might even destroy that whole family, wait, but the events! Ohhh, my stomach hurts!

[@calinevideos]

If he traveled to the past to a day before his parents where born and killed his grandfather he would've been still born as his grandmother must've been in like 9 month pregnant back then. This story says it a bit wrong but the original paradox is amazing

[@AMC2283]

I don't believe in time paradoxes, only anomalies. if you kill the old man you don't just disappear--you exist in the past because of time travel, your birth years later has nothing to do with it. you get back to the present to find no one knows who you are because "you" were never born.

[@rinneapolitan192]

+AMC2283 This makes sense, thank you for solving this problem lol. Never looked at it from a different angle.

[@AMC2283]

+Rin Neapolitan helping people understand the universe better one you tuber at a time :)

[@Null64]

+AMC2283 Sounds like the alternate reality scheme though where as there's different alternate universe/worlds/reality's so what your saying that theres multiple outcomes and no real penalty if one were to kill his grandfather? Only thing that would or could happen is upon arrival back to the present nobody would know who you are? Because you were never born. Not a big deal really because you would just have to deal and meet people over again. It sounds like the alternate universe theory and I kind of believe in this too. Only because theres an infinite amount of possible outcomes that could and would happen meaning that anything that was possible can have impact and change a quantum signature for a different reality for each and every outcome how its played out to determine a persons existance or even general things and events that happened around the world. Yes I believe in this theory also its good you brought it up.

[@AMC2283]

+Joe Zipperer Thank you, though I think it's a littler simpler. I don't think you have to get alternate universes involved. I think you're simply changing events in your own universe.

[@anrick1362]

thank you. finally someone else thinks this way.

[@yashkesari]

We can't go back in time. We can only move forward as we are while I am writing this comment. But imagine if the universe collapses and time moves backwards... what would happen then ? 1. People would be born from their graves and would die in womb. 2. People would meet their kids , then meet their life partners and then meet their parents. 3. Health will keep on improving as time progresses. 4. Some people would be born from accidents and some from fire burns. Some will just come out of water. 5. Knowledge would gradually decrease day by day and happiness will increase for any person. 7. Bad eyesight person will gradually begin to see more clearer. 8. Water from land would rise up to become rainfall... 9. Apples would jump up from the soil and cling to the tree. 10. Everything would still make perfect sense even then..

[@Jonathan1234]

Lmao nigga

[@lunarxphoenix]

I was thinking that whatever you do in the past won't effect the present, as it never happened the first time around. (Ex. When you kill your grandfather and go back, nothing will change because around your grandfathers time (the first time around) no one has killed him.) I was thinking that doing something in the past won't effect the present. Because think about it, if time travel was a thing as of now, do you really think everything could be the same? I don't think going back changes anything.

[@NanenMauricio]

Yeah I think there is a theory with a "solution" for this paradox, the theory explains the paradox by changing the grandfather and the timetraveller by atoms, if I'm not mistaken it ends similary, you were already born, so nothing changes. Also, is that Markiplier on your avatar?

[@hifijohn]

I think if time travel could work it would be forward only thing. basically just accelerating the natural flow of time. going back in time creates too many problems.

[@PigmentBlanks05]

Am I the only one here from 2021 ?? Bcz all the comments are like 5,6,7 years old !!!

[@MPM6785ChitChat]

I've traveled now so that l can say Hi 🤭

[@QuantumDice]

Even in the case of a "only one timeline" universe this is not a paradox If there is only one "time line" than it's impossible to kill your grand father in 1920 because in 1920 there was no visitor from the future trying to kill you grand father... Or if there was a time traveler who tried to kill you grandfather, well, obviously he did not succeed because you grand father is still there to tell the story. So if the traveler from the future was you than you already know that you will fail...

[@knucklez92]

can someone answer this question. suppose to kill your grandfather after you are born. then what happens. would you still have the idea to go back and kill him

[@breeallison6118]

If i could time travel, i will be the biggest Spoiler.

[@ladyalfhildrforestofvioletmist]

+Bree Allison Hello there, River Song... hehehe :)

[@QuantumDice]

In fact it's really easy to travel into the future, if you want to go one hour into the future, just wait one hour ;)

[@DragonUltraMaster]

What I just don't get is: You already EXIST to shoot your grandfather. You go back in time, you do your business with your grandfather, he dies. You still live on... right? Sure, the future for your grandmother would be different (and everyone else) *I GUESS*, but I just don't think anything really could stop you. I go from let's say universe 1 from where everything started. I timetravel back in time which brings ME to universe 2 (becuase I shouldn't exist there in the first place but thanks to the time mashine I do), shots or does whatever cruelty to my grandfather but still lives another live in that universe 2 with a young grandmother but still doesn't know her that much other than knowing who she is and what she has told you how her life was.

[@AERIEDM]

Travelling back in time is possible. Killing your own Grandfather is possible. You will still exist. You are always in your own time line. Only when you travel forwards, you will not be in the same universe. You'll be in a parallel universe whereby your Grandfather never existed and you would be considered a person from nowhere. You'll still be in your own timeline.

[@CamiloSanchez1979]

Time can only be controlled when timotron particles are more widely understood

[@HugaHoodie95]

haha that made me laugh. it's a good point though! however I think that the general point is playing upon the ideas of 'The Butterfly effect' though. If you change one thing slightly in the past, this could affect millions of variables that lead to time travel never having been created

[@LittleJupiter101]

This is why you don't mess with time shenanigans.