Solution to the Grandfather Paradox
Why Worldbuilding Stack Exchange recommends it
Worldbuilding Stack Exchange answerers and askers point to it as a quick, physics-grounded reference when designing or analyzing consistent time-travel rules in a fictional world.
Recommended by 1 people across 1 different months, 2016 to 2020.
What it is
A short minutephysics explainer on the grandfather paradox, drawing on computational complexity and closed timelike curves to describe how a consistent time-travel loop could resolve it. It follows up an earlier video and links to Scott Aaronson's lecture notes and a technical paper.
What people said
Recommends Plutian · 2020-03 · Worldbuilding Stack Exchange · on “In a world with time travel, would it be possible to be your own mother's mother?”
This is of course a variation of the grandfather paradox. Here is an interesting video about it [this video] . My take on this is: No. Even when omitting the obvious paradoxes and creating the situation where you replace your grandmother, you are not just the sum of your grandparents' genes. You are also the result of (however minute) random mutation. You could obviously go back and get pregnant from your grandfather, but the grandchild you produce would not be you. Therefore you and your grandchild could not exist on the same time line.
Cites Z.Schroeder · 2016-08 · Worldbuilding Stack Exchange · on “Making an internally consistent, logical set of rules for time travel (based off of this video)”
[this video] Something similar to this. Okay, so the basic plot structure I want is that there are two parallel timelines, both of them potential futures for our world. These two timelines have become entangled, and now the fabric of their branes are beginning to collide, meaning eventually one or both will either be destroyed or absorbed into the other. Utilizing alien technology (long story), one of these parallel timelines creates a CTC that'll take them back to before the event that triggered the separation to manipulate history in such a way that their timeline becomes more chronologically "certain" and therefore more likely to survive the collision. What I'm almost "certain" of myself is th
Cites Trish · 2020-02 · Worldbuilding Stack Exchange · on “Can a world where everyone has a time machine be consistent?”
Yes and no. All time travel depends on how restrictive time travel is. There are several types of time travel! Note that if everybody had a time machine, Hawkins should have had a booming party on 28th of June 2009, to which he sent out the invitations on the 29th of June. He gave it to remind of his 1992 conjecture that travel into the past is effectively impossible. Flipflopping Time Whenever you travel back and try to prevent something, you create a closed 2-state loop for yourself, and are therefor forever trapped in either of the states. Jack Traveller travels back 50 years and prevents his grandfather Albert Traveller meeting his grandmother Janine Jacobs by running him over with a car