Solution To The Grandfather Paradox

Solution to the Grandfather Paradox

What if you went back in time and killed your own grandfather? Would you still be born? Or would you have thus killed yourself? Thanks to Google #sciencegoals for sponsoring this video!

Link to the previous MinutePhysics video:

If you could travel back in time, and you killed your grandfather, would you be killing your future self? What do physics, complexity theory, and computer science have to say about this famous murderous time-travel paradox?

Scott Aaronson Notes that discuss time travel and computation, computational complexity, closed timelike curves, and the grandfather paradox:

Technical paper that discusses the same thing:

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This Post Has 40 Comments
  1. Your grandfather would gave a small chance of having the same sperm fertilize the egg also ur father, soooooo there would be a small chance of you doing that again…

  2. I have a question.
    "If a ball is travelling at a finite speed in a fluid at present then how much time is required to it slowdown to rest only considering the FLUID FRICTION.??
    i think it would take infinite time…!!
    it came to my mind from nowhere.
    plz answer it…

  3. What if time traveler grandson goes to the past, has sex with his grandmother, gets a daughter and that daughter has the grandson who time travelled? Basically the grandson will become a grandson, a grandfather to himself, a son of his mother but also the father of his mother?

  4. You didn’t not explain this well…. I still have no understanding as to what the solution to this fucking paradox is. You talk way to fast lmao.

  5. The solution is very simple; everyone makes it way too complicated. Because we know for sure your grandfather wasn't killed before your parent was born, that means that when you went back in time, you didn't kill him.

  6. Not sure I really understand this as a solution to the paradox. Yes the timelines keeps looping around each other; that’s the entire point. Doesn’t it break the flow of time if the continuum is constantly looping around itself? You kill your grandfather, you’re never born, you never go back to kill him, you’re born, you kill him etc. Forever.

  7. As a quantum physicist, I should tell you quantum superposition has nothing to do with doing things in parallel. In fact, during quantum superposition, particles are not doing anything. Quantum superposition is a statement about the indeterminacy of the states of a particle. If no information is available about a system from prior measurement, then the system is in quantum superposition, because the state of the system does not exist, meaning there is no such a thing as "the state of the system". The system only acquires a state (randomly) the moment you perform a measurement, which amounts to altering the wave function, which is why it acquires a state in the first place. As such, quantum superposition is a terribly bad explanation for time travel, and this video also just does a bad job at invoking quantum mechanics in general.

    Also, the grandfather paradox does not really exist when you consider a purely scientific perspective of time. Time is not linear as you suggest it, it is not frame invariant, and it is not disconnected to time and quantum fields. As such, the concept of the paradox does not make sense: the paradox in the first place assumes the popular non-relativistic view on time, which happens to be far from accurate.

    The real problem with time travel has nothing to do with paradoxes. It has to do with the fact that, for instance, an imaginary ratio of mass to energy seems to be physically impossible by virtue of how these quantities work, or that no exotic matter has ever been observed to exist.

  8. It’s mean if I go back it will kill my grandpa but I’m gonna be a new grandpa but my dad not gonna born again?

  9. If these ideas are possible, why the time travelers or dimensional hoppers are so good at hiding their identity from us?

  10. I know that thousands of people have already thought about this, but what if just travel back again before the time killing the grandpa? I imagine some sort of rewind will happen.

    Edit: (Hey don't be mad, It's just a talk.)

  11. You can not go back to kill your grandfather. If u go back in time, it is only because you exist in the first place. That means that you never killed your grandfather that is why you are here. You cant exist to be able to do this murder and exist only because you will fail to do so if you go back in time for whatever reason.

  12. I have a better solution: If you go back in time, your grandfather will be invincible, so you don't get to kill him lmao.

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