You have been working on your plutonium-powered time machine for years, and now you finally succeeded!
At least, you thought you did...
After extensive testing with sending back and forth various objects, plant seeds and small animals, you decide it's time for the first human test.
All you have to do is let the time machine select a random date in time and transport you. Then, press the reverse button. That press will start a complex calculation to determine the exact amount of energy needed to make a similar jump in opposite direction of time. Once that is done, the leap will be initiated.
After selecting the random date option, you notice something strange. Sparks start shooting off the panel, and the time machine shakes heavily. Oh no... the heavy load caused a minor short-circuit. The heavy shaking causes you to hit your head and you pass out...
When you wake up everything seems normal. At least, as normal as a trip through spacetime can be. You are successfully transported to a different time, and all you have to do now is press reverse. You hold your finger over the button but pull it back the last second. In shock you read the travel log screen. You haven't just been sent to another time, you've been sent to FIFTY other times!
In other words, after you passed out, 50 parallel copies of you were created and scattered throughout spacetime. All in identical copies of the time machine.
You calculated before that this could happen and realise that pressing reverse is dangerous. It will start the return calculation and potentially send you back. However, each copy of the time machine processor is linked, such that if you and your copies press reverse more than once, the additional presses interfere with the calculation initiated by the first press. That will send you to some unknown place in spacetime from which you will never be able to return... But not pressing the button doesn't seem like a good option, as then you will stay where you are and never return home either. There is no way of communicating with your other selves.
When you take another look at the panel you notice that the battery of the time machine is starting to run out. You have to make a decision quick, or you will be too late to start the return cycle.
You weigh your options. If you don't press, you will know for sure that you will stay in an unknown time and never return home. However, if too many of you press the button, the return cycle is broken, and you will also end up lost in time and space.
You are desperate, but you know you have to keep your hopes up and rely on your awesome logic skills. Suddenly you realize something that may be helpful. Your other selves have the same logic skill as you. And they know you do too. And they know you know they know you do...
Is there a way you can make you way home? What is the best tactic to maximise your odds? And what chance of survival do you or your copies have?
- 50 copies of you a trapped in a time machine
- All copies, including you, are equal, but independently assess the situation
- There is no way of communicating with your other selves
- There is a return button, but it only works if one person presses it. If multiple do, it sends all of them to a random place in time
- The return button only works for the person(s) that pressed it
- The return button can only be pressed once, otherwise the same will happen as if multiple people do: you overshoot your return trip
- You have perfect logic, and so do your copies
- No telepathy, or anything funky related to the fact that you are copies of yourself. The puzzle would work also for 50 random people with perfect logic.
- You have access to things you had in your pockets while travelling. Including your phone with calculator and other common apps you think are necessary. No internet though!
Inspired by a puzzle from Vsauce2 (Video includes answer to that question, so spoiler alert! https://www.youtube.com/watch?v=NkYCWqzBc7M )