1. Persistence of vision makes the pulsing colours blend to White when stationary. When moving, the colours pulse in different positions, hit different parts of the retina, so are detected individually

  2. There’s not really enough information to explain definitively. First and foremost, what type of light source is that? It looks white when it’s still, but if it is actually achieving that effect by strobing the three primary colours (red, green and blue) in quick succession, then that would explain the effect as the “after image” will be a different colour in each position in the arc of movement. That’s the best I’ve come up with.

    nb. the technical quality of this animation is awful. I’m assuming that’s nothing to do with the effect, but it would be nice to see a decent quality version.

  3. I’m guessing the tube contains banks of different colour LEDS red,green,blue, each is pulsing at a different rate, so you literally see each bank in a different position.

    1. I’d agree, save that the rate is surely the same. It’s the phasing which is different. That is the red, green and blue sources are not illuminated at the same time, but they actually flash at the same rate (frequency).

    2. It doesn’t need to have banks of different colored LEDs. They make single LEDs that can glow different colors depending on which leads have current in them.

    3. @mark p

      At a technical level, those multi-colour LEDs are 3 single colour LEDs, but with some extra electronics to switch the colours using various techniques. However, they are, at heart, still three LEDs with the primary colours, albeit in one package.

      Incidentally, that’s not how (most) so-called white LEDs work. Those use a phosphor layer to “convert” light from blue or near-UV LEDs to produce a “white” spectrum. Richard’s “wand” would not have worked with those.

  4. I’m not sure if it’s a video quality issue at my end but I don’t see a white light at all, when stationary I see a light of rapidly-changing colour with magenta and cyan predominant.


    Richard is asking IF you can explain. That needs just a YES or NO.

    The proper answer will follow on Monday, Please do not spoil it for the rest of us.

    1. OK Barry – we realise you live in a different universe to most of us, but is it Friday where you are? It’s the only explanation I can come up with for your comment.

    2. If Richard wanted us to not post the answer, he would have put PLEASE DO NOT POST YOUR ANSWER in the description.

    3. @Stephen Jones:

      Stephen, I do not fear a gentle ribbing at your hands if I have in some way offended against Internet Etiquette in my comments,

      Yet I suspect instead you have been misled by an oldworld paper calendar. Time does not exist on the Internet in the way you would like, In the twenty five years since Sir Tim Bernard Lea invented the Internet there have been over 175 (25×7) Fridays. Yet all those posts whether made on a Friday or not still exist at once and can be retrieved by a search engine such as Google.

      It matters not then the date of a post. It matters most the intention of the poster. Richard did not say post your answer. I do not believe he has ever once said post your answers. He does not want our answers. He wants our timed reactions.

      We do not off course have to fulfill his wishes, Some of us have ventured to post answers when it has been clear that the early answer posters are posting misleading information. That is a public service which transcends any duty of care to RIchard.

      As Sir Tim Bernard once said: Information wants to be free. He has given us a way to free it. We should honour his memory and keep it free while respecting Richard’s wish to be the first to speak, Is that so complicated?

    4. @Barry

      Richard has posted dozens of these sort of “can you explain” posts, and there is always an implicit invitation to supply such an explanation. That’s much in the way that exam questions are often worded where much more than yes/no replies are required (even though many of the schoolboy pedants among us often thought we could justify them as valid replies).

      To make things clear, it’s only the Friday puzzles which have (explicitly stated) requests not to post answers and where an answer will be provided on a Monday. These sort of “can you explain” posts from Richard occur less frequently, and not on a regular basis. Indeed, in many cases you never get the full explanation, often because they aren’t Richard’s illusions. In none of these cases are suggested explanations “banned”. Now he may post an explanation on Monday – or maybe another day – or maybe never. We don’t know (although as this is one of his illusions, rather than a mystery he’s come across, then most likely an explanation will be forthcoming).

      To berate those who have posted suggestions based on constraints that you’ve inferred yourself, rather than what is explicit in the post is, I feel, based on your interpretation and not supported by precedent.

      Or, to be much more succinct, if Richard didn’t want possible explanations, he’d have made it explicit, as he does on the Friday puzzles.

    5. errrr, ” In the twenty five years since Sir Tim Bernard Lea invented the Internet there have been over 175 (25×7) Fridays. Yet all those posts whether made on a Friday or not still exist at once and can be retrieved by a search engine such as Google.”

      1) he didn’t invent the internet, just www / HTTP ( a protocol that works over the internet )

      2) 175? maybe you want 25*7*52 ( 9100 fridays )

    6. It’s amazing how a little jokily made comment (and I smiled and appreciated it) can be taken the wrong way (or have I misread the way this thread has gone – it’s possible).
      Oh, and by the way it’s Sir Tim Berners Lee not Sir Tim Bernard Lea 😉

  6. Richard is hitting a guinea pig, but I can’t explain why the guinea pig is invisible. It’s a clever trick but you are a cruel man, Mr Wiseman.

  7. I’m not sure what I’m supposed to be seeing, but the light never looks pure white to me. Even when still, I can see the different pulsing colors.

  8. Please excuse Barry Goddard, he knows he’s an absolute fuckwit but can’t help himself. PS nicely done Richard.

  9. I reckon it would look even better for people , at a party , who may have had an extra wine or two.
    Good stuff…where can they be purchased. ?

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