Can you solve the time travel riddle? – Dan Finkel

Can you solve the time travel riddle? – Dan Finkel

Your internship in Professor Ramsey’s
physics lab has been amazing. Until, that is, the professor accidentally
stepped through a time portal. You’ve got just a minute to jump through
the portal to save him before it closes and leaves him stranded in history. Once you’re through it,
the portal will close, and your only way back will be
to create a new one using the chrono-nodules from your lab. Activated nodules connect to each other via red or blue tachyon entanglement. Activate more nodules and they’ll connect to all other nodules in the area. As soon as a red or blue triangle is
created with a nodule at each point, it opens a doorway through time that
will take you back to the present. But the color of each individual
connection manifests at random, and there’s no way to choose
or change its color. And there’s one more problem: each individual nodule creates a
temporal instability that raises the chances the portal
might collapse as you go through it. So the fewer you bring, the better. The portal’s about to close. What’s the minimum number of nodules
you need to bring to be certain you’ll create a red or
blue triangle and get back to the present? Pause here if you want to figure it out for yourself! Answer in: 3 Answer in: 2 Answer in: 1 This question is so rich that an entire
branch of mathematics known as Ramsey Theory developed from it. Ramsey Theory is home to some
famously difficult problems. This one isn’t easy, but it can be handled if you approach it systematically. Imagine you brought just three nodules. Would that be enough? No – for example,
you might have two blue and one red connection,
and be stuck in the past forever. Would four nodules be enough?
No – there are many arrangements here that don’t give a blue or red triangle. What about five? It turns out there is an arrangement of
connections that avoids creating
a blue or red triangle. These smaller triangles don’t count because
they don’t have a nodule at each corner. However, six nodules will always create a
blue triangle or a red triangle. Here’s how we can prove that without
sorting through every possible case. Imagine activating the sixth nodule, and consider how it might connect
to the other five. It could do so in one of six ways: with five red connections, five blue
connections, or some mix of red and blue. Notice that every possibility has at least
three connections of the same color coming from this nodule. Let’s look at just the nodules
on the other end of those same three color connections. If the connections were blue, then any additional blue connection between
those three would give us a blue triangle. So the only way we could get in trouble is if all the connections
between them were red. But those three red connections
would give us a red triangle. No matter what happens,
we’ll get a red or a blue triangle, and open our doorway. On the other hand, if the original three connections
were all red instead of blue, the same argument still works,
with all the colors flipped. In other words, no matter how the
connections are colored, six nodules will always create a red or
blue triangle and a doorway leading home. So you grab six nodules and jump through
the portal. You were hoping your internship would
give you valuable life experience. Turns out, that didn’t take much time.

100 thoughts on “Can you solve the time travel riddle? – Dan Finkel

  1. Get the solution to the bonus riddle here:! Also, the first 833 of you who sign up for a PREMIUM subscription will get 20% off the annual fee. Riddle on, riddlers!

  2. When I heard that the professor’s name was “Ramsey”, it made me think, ‘Huh, that reminds me of Ramsey Theory.” Little did I know, that was the answer! Arggh, darn it!

  3. Easier explanation: With six nodules, each one needs to connect to five others, which means at least three will be in the same color. Now let's take one nodule and look at the end nodules of its three connections of the same color. These three nodules also need to be connected to each other, and if one of these connections is of the previous color, it will be a triangle with the starting nodule. If none of them are, they will all be of the same color, hence they will then form a triangle.

  4. Think 3D and the correct answer will be a minimum number of 4. Yes 6 is correct when we think 2 dimensional, but who says the nodules must all be on a flat surface? You CAN think 3D. Just put 3 nodules down on the ground shaped like a triangle. Hold the fourth nodule exactly on top of the triangle’s center above the ground. You now have a pyramid with 3 triangles in the air and one triangle on the ground. Now out of 4 triangles, you will always have at least one all-blue or all-red triangle.

  5. This is good sense

    You put 6 nodules
    Portal opens
    You get in completely
    Unfortunately for you, you accidentally put tomato sauce on 1 of the blue nodules
    Your stuck in between the space time continum
    How unlucky you are


  6. Either throw the box to the scientist or you jump through the portal with the whole box and start with three nodules and add one more each time till it works

  7. "What's the minimum number of nodules you'll need to bring to guarantee you create a fully red or blue triangle?"

    Me: Well, Prof., it was nice knowin' ya.

  8. Why not just make another time portal with 3 nodes before you even go through the portal, then deactivate the time nodes, and go through the portal to save the professor with those same 3 nodes? Then if the portal fauls, why not just make more portals to save him, after you find which nodes you need.

  9. You bring a lot of them but only use them one at a time until a portal opens. You could get lucky and only have to activate as few as three.

  10. To be completely honest I got it perfectly correct on my first try my logic was if there's two colors of lasers then if I bring twice the amount of lasers necessary then with the 50/50 split their there should be a more than even odds that a red or blue triangle would form

  11. Me an intellectaul: I'll just take the whole box and keep on throwing some until I get a triangle because they only cause instability once used

  12. Tachyon entanglement is impossible, Tachyons travel faster than light, which requires it to have no information, so what would you transfer?

  13. bonus riddle i just say bring 12 1 goes through if a portal is left u go through if not u throw the other 6 out for another portal

  14. i guessed 5 since you'll either get a ratio of 4:1, 3:2, or 5:0 which will give you at least 3 nodules before throwing the rest away
    i forgot the connection rule while doing this logic

  15. Bonus riddle: if you open two portals you create a time sh*t splattering continuum chaos that kills the entire universe, even worse than thanos snaps, because you give entrance both to the 50% thanos snapped in one timeline and the 50% he snapped in an alternate timeline, bringing complete destruction


    I was like "okay need three to form red or blue, two colors times three modules , 6!" I was high key being sarcastic BUT IT WORKED

    This day will go down in history for me

  17. Solution: bring 5 and you will have at least 3 of one color. Move them into the correct positions to link to each other and BOOM ur safe

  18. 4:02 yes
    cause didn't they say that no matter what you do there will always be a red or blue triangle so you use the blue triagle then the other uses the red

  19. Imagine if our character in these riddles didn't immediately know the answer to these problems…
    "Professor, no! Ah, alright. I've got one minute. Er, each module links with another in a random color, how many do I need to bring? I'll just take several and join them together! No, too many will cut my arm off… Hang on, what if I made several sets of 3? It must work at some point!"

    "…Wait, the one minute's gone. Ah well. Wait, there's a Ramsey Theory book in the lab that described the purpose of the problem, and my mentor wrote it? Why didn't I read it?"

  20. You didnt show the other combination the 6 nodes could have. What about 1 one having blue nodes and the rest red or vice versa. There are more than just 6 combination

  21. Why can’t you just take the entire box? You can do trial and error all you want, and you can make multiple portals so both of you can escape, if the bonus riddle was in the situation

  22. Wait…before you needed a doorway.. THEN YOU FORBID THE THING YOU NEED
    Edit: oh…you were saying how many u need…ok

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