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It was a normal Tuesday
at the superconductor,
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until a bug in the system created
a small situation.
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Now your team is trapped in eleven
separate pocket dimensions.
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Luckily for you, there’s a half-finished
experimental teleportation robot
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that may be able to get you all home,
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if you can figure out how to work through
the quirks of its design.
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Over interdimensional radio,
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your engineers explain
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that the robot can teleport into the
alternate universes you’re trapped in,
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but it’ll do so completely at random.
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The robot has two levers
and one big button.
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When it appears,
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you just switch the position of one
of the levers from A to B or vice versa,
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and then the robot will note your
dimensional position
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and teleport to another of the eleven
dimensions at random.
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If it shows up again, you’ll have to pull
a lever before it’ll teleport away.
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When anyone presses the button,
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the robot will bring everyone who pulled
a lever back home.
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Anyone who didn’t will be lost
in the multi-verse forever.
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The challenge is to make sure everyone
has pulled a lever
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before anyone hits the button.
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While you can talk to each other now
over the interdimensional radio
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and agree on a plan,
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the robot’s teleportation technology
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will interfere with all attempts
at communication once it arrives.
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You won’t be able to attach messages
to the robot
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or scratch notes into its superstrong
alloy body.
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Your only way to communicate information
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is to change the position of exactly
one lever or hit the button.
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What plan will make sure
everyone gets home?
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Pause the video now if you want to
figure it out for yourself.
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Answer in 3
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Answer in 2
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Answer in 1
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It would be nice if you could set
different combinations of the levers
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to indicate who’s already
been visited by the robot.
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But it has only two levers.
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That gives four combinations—
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far too few to communicate
about 11 people,
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especially when you’re forced to flip
one to send the robot onward.
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There must be another way.
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The critical insight is that not
everyone has to know
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when every pocket dimension
has been visited.
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If one person accepts responsibility
ahead of time for hitting the button,
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then only they need to know who the robot
has visited.
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In fact, they don’t even need to know
exactly who’s been visited…
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just how many people have been.
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You volunteer to be the person in charge
of pressing the button
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when the moment is right,
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and give the following directions
to everyone else.
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Your plan is simple:
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you’ll use the left lever to count visits,
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and the right lever will have no meaning,
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so there’s no harm in
moving it up or down.
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Each of the others will pull the left
lever
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from position A to position
B exactly once.
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If the robot appears with the left lever
already pulled down,
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or if an individual has previously pulled
the left lever down
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at any point in the past,
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then they should move the right lever.
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You, meanwhile, will be the only one who
ever resets the left lever from position B
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to position A.
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This gives you a way to count how many
people have been visited by the robot.
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Everyone needs to pull the left lever
down exactly once,
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and you’re the only one
to pull it back up.
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So you know that the tenth time
the robot visits you
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with its left lever in the down position,
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it must have visited
all ten of the others.
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And that means you’re safe to press the
button and teleport everyone home.
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It may take a while–
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most likely the robot will need to
teleport around 355 times;
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but better that than leave anyone behind.
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Your teammates phase back into your home
dimension one at a time.
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The mission proves a great success.
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Well...mostly.
Margarida Ferreira
Please note:
Title:
Can you solve the multiverse rescue mission riddle? - Dan Finkel
https://www.youtube.com/watch?v=ZmaeljnPOu4
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