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Physics World at 25: Puzzle round-up

Physics World at 25 Puzzle

By Louise Mayor

Twenty-six days ago we launched the Physics World at 25 Puzzle with the first and easiest of the five puzzles in the series. Today we announced the fifth, final and most fiendish puzzle of all.

Did anyone out there manage to bag the whole set? See where you rank by entering all five answers, in sequential order and as a single string of text with no spaces, in the box below.

However you do, we sincerely hope you enjoy trying the puzzles.

For any frustrated puzzlers out there who are at the end of their tether and want to know the answers, do not fret: the solutions will be revealed in the January 2014 issue of Physics World.

Physics World is available online and through our apps to all members of the Institute of Physics, with IOPimembership costing just £15, €20 or $25 a year.

We will also announce the answers on this blog in January – to make sure you get a reminder, you can sign up to our newswire, which each week highlights the latest content on

Anyone for any more? GCHQ also created the Codebreaker Challenge for the London Science Museum – an interactive set of puzzles that we highly recommend.

Enter your answer here

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  1. Chris


    Not bad for a non-physicist!

    A lot of fun but I’m kinda glad that I’m free of them now!

  2. Robin S

    #12. Now to get back to work…

  3. Leigh

    #16 overall! Phew. That was both fun and infuriating at the same time. See everyone again in 25 years for the next one? :)

  4. Ruth R

    #17 overall (#23 on the final puzzle). I’ll really miss these weekly puzzles – thank you very much Physics World for the brain-mangling I have greatly enjoyed throughout this October!

  5. Mat W

    #21 – probably lost a bit of time having to re-work out puzzle 2 after not writing my original answer down. I’ll cast a vote for a regular puzzle slot!

  6. Tobz

    #22 – like Mat I also had to rework puzzle 2!

  7. Phil


    My brain hurts

  8. S

    #24 I can go to sleep now!

  9. Frank

    I got #25! :-)

    Thanks for the puzzles!

  10. Good work everyone! Thanks for your feedback – it’s very much appreciated and we will take it into account when planning future content :)

    Has anyone tried the Codebreaker Challenge?

    • Steve

      Yes, just tried out the Science Museum challenge. Quite fun and relaxing, but very quick and simple after the challenge of the last few puzzles here. Still, nice to give the brain a bit of relaxation to wind down.

      Thanks to the puzzle setters, and the solvers leaving various clues which certainly helped along the way. My favourite was probably #3, closely followed by #4. Really like parts of #5, but I’m a bit biased against it right now having got bogged down for so long due to a couple of wrong turns. I blame Coriolis and Stokes. Well, and myself.

      • Dead or alive

        Did you do the master level right at the end after you finished all the scoring levels?
        I got it out with a bit of cutting and pasting!

  11. Natasha

    #28 I’ve done more thinking this month than I’ve done in years!

  12. lisa

    #34 .. finally!
    All great fun.
    What will we all do next Tuesday??

  13. Ezekiel Romero

    #35…at last!
    Thanks for the great puzzles! :)

  14. FoxyV

    #39, Out all day and then had to do 1&2 again as I had thrown away my notes and couldn’t remember the answers! Great fun though..

  15. Ian

    #40 you must do this again – but not too soon I have real work to do :))

  16. Laura

    #46, also a non-physicist. Thanks for helping pass some long hours! I had to re-do puzzle 2 as I didn’t save my notes. My only feedback was for puzzle 3 – having never heard the story/joke before, I would never have logically reached that conclusion with the information provided (had to rely on people’s hints). Back to work for me…now what will I do on Tuesdays??

  17. Dennis

    #57- not bad for a retired clinical biochemist who last did physics at A level in 1968! Great fun and loved reading the original paper for Q3 the humour of which I appreciated.

  18. vicky

    #60 held up by getting massively stuck on puzzle 5, which was quite tricky for a non-scientist. I got there in the end though.

  19. Dan

    #61. I was expecting some kind of link between the five puzzles, like the solutions together spelling out something meaningful.

  20. Les

    #63 finished puzzle 5 in the early hours of this morning-all 5 great fun.I’ll miss them now.

  21. Vasia T

    #66! Ouffff!

  22. TheOldRic

    #67, close to my harmonic average. For the 5th, shoot that woman! (No, not really as then we might not get next year’s.) Thanks to all concerned.

  23. Graham W

    #53 sometime Thursday morning I think. Very enjoyable – don’t leave it another 25 years!

  24. Ian P

    #69. Lots of wrong guesses on puzzle 5 and puzzle 4 was a real face-palm d’Oh! moment when the penny finally dropped. Thanks to the puzzle-setters for a lot of fun.

  25. Lorax

    thanks to all
    when’s the next one :-)

  26. Julia

    #73. (I started the last one a few days late and then it took me absolutely ages!)
    Many thanks to everyone involved for organising these.

  27. Andrew W

    #77 Nice mix of puzzles with number 2 and 4 my favourite. Learned a lot about cryptography and physics over the last few weeks. A big thank you to all involved it was fun.

  28. Dead or alive

    Puzzle 3 was nice, I have read one of Gamov’s Mr. Tompkins books and knew about alpha…
    Puzzle 4 was more code-breaking than physics.
    Last one was a hard slog as I was going nuts…

  29. James E

    #84 – Took some wrong turns with q5 but got there in the end. Thanks for the mental work out PW and GCHQ. Now… back to the more difficult problems of real life.

  30. Malisha

    #86 :)))

    the fifth one was tough, but finally i got the EUREKA moment. nice feeling.

    thanks, thanks, thanks! i want more of this stuff :))

  31. Dartmoor Graham

    Just discovered this round-up page. Was #89. Thanks Louise et al.

  32. Pete

    92nd. Got some help for puzzle no. 3 today, then persevered with no. 5. Still not sure about METEOR or COINCIDENCE.

  33. Nick Shearman

    #97. Happy with top hundred as real life got in the way a lot. It was huge fun though and the Codebreaker Challenge awaits when I finally find time. Many thanks to those involved in giving us these puzzles.

  34. JW

    #99 well chuffed with the rolled up score being my highest score of the series.

  35. Manateeadams

    #104 made my dull night shifts fly by so thank you, anyone know where to find similar puzzles?

  36. Chris-switzerland

    #112–Frustrating at times (most of the time?!) but still fun. Thanks!!

  37. sarah b

    #118, finally, must be one of the last! Great fun :)

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