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GeeKay

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About GeeKay

  • Birthday 10/19/1950

Profile Information

  • Location
    Lincoln UK
  • Interests
    Cycling, swimming, reading, writing and generally making the best of life. I intend to do a lot of motorhome-style travelling in the nearish future, complete with my favourite touring bike and a decent sized telescope. And I'm looking forward to it - immensely.
  • College Major/Degree
    BA (hons) English Literature at the University of Wales, Aberystwyth
  • Favorite Area of Science
    Astronomy
  • Occupation
    Ex-private tutor (English Lit). Now retired.

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  1. So the OTP is a Vigenère cipher, after all. Simon Singh does a good job explaining Vigenère ciphers in the book - good enough for a tyro like me to understand the tabular process. The take-home message then is that a third-party can get an OTP's plaintext from the (revealed) key by the above method. Thanks also for the links.
  2. This post refers to the (excellent) primer on codes and ciphers, namely The Code Book by Simon Singh. The question itself concerns the one-time pad cipher, the one form of encryption which is claimed to be truly unbreakable, that's to say proof against any known form of cryptoanalysis. . . short of telepathy? One aspect about this cipher is bamboozling me, however. Namely it's this: would it be possible to crack a given one-time pad cipher if one was already in possession of the key? Singh offers this example: Key: P L M O E Z Q K J Z L R T E A V C R C B Y Plaintext: a t t a c k t h e v a l l e y a t d a w n Cybertext: P E F O G J J R N U L C E I Y V V U C X L Unfortunately, I cannot see how a hacker with full knowledge of both the cybertext and the key would be able to generate the above plaintext. Unlike the key of a Vigenere cipher, for instance, the above key has no obvious structure, contains no recognisable words. It is entirely random, which means it's incapable of providing clues about the plaintext to a would-be hacker. And yet, Singh goes on to state that possession of the key would enable just such a hacker to break the code. But how exactly? Being structureless means the key would resist frequency analysis, for example. Chaos is chaos, after all. The only possibility that comes to mind is that the one-time pad is itself a Vigenere cipher, but this is only a wild guess on my part. Whatever, something fundamental is missing in my understanding of codes and ciphers which I'm simply not getting ☹️ So any help here would be greatly appreciated. Many thanks!
  3. Having recently read up about the Beale Papers and the seeming impregnability of its two remaining unbroken ciphers to cryptanalysis (even allowing for the possibility that they may be fake) I should like to know if quantum computers will be able to crack such so-called 'book ciphers'. I gather that the one-time pad cipher is said to be - when applied correctly - theoretically impossible to break by any known means, which may be a comforting thought. So does the same invincibility apply to book ciphers like those two (alleged) ciphers contained in the Beale Papers? Many thanks. https://en.wikipedia.org/wiki/Beale_ciphers
  4. Yes, I sort of guessed that beam spread etc might be too problematic beyond a certain distance. So it appears then that optical telescopes are still the only reliable means we have for detecting asteroids and so forth. All the same, spotting any incoming comets by optical means alone while they're still beyond the Jovian snowline could be quite a challenge, especially given their generally very low albedos. I can't (as yet) find the article which prompted this thread, but a recent one from Centauri Dreams may suffice: https://www.centauri-dreams.org/2021/09/02/deep-space-network-a-laser-communications-future/
  5. This question concerns possible future uses in space of Lidar (Laser Imaging, Detection & Ranging) with regards to the detection of incoming asteroids, comets etc. Thus what would be the limiting distance of a Lidar system of a given power output in terms of resolution? Could its laser beams in theory be able to extend from Earth orbit to as far away as (say) the Main Asteroid belt, or even further afield? Or would the beam's width or 'spot-size' by then be too distended/incoherent to be of any use? Forgive any imprecision in the use of scientific terms here. Many thanks.
  6. It's okay. I have it now. . . it's the 'Hill Sphere" set of calculations I was seeking. Phew. . . https://en.wikipedia.org/wiki/Hill_sphere
  7. I used to have an excellent online calculator that enabled me to show the possible orbits of a satellite around a larger secondary body (e.g. a moon) which itself was in orbit around (say) a planet. Unfortunately my local PC repair shop unwittingly deleted the calculator during a refurb. And since I can't recall the scientific/technical term for this "three-body" gravitational arrangement, I'm no longer able to locate online the calculator in question. I would therefore be very grateful if anyone can help me here. PS. Unhappily I don't have anything like the mathematical skillset to do these calculations by hand. Thanks in advance.
  8. Yes, I think I begin to get it now. Thanks, studiot, for your detailed and helpful explanations. Food for thought, indeed. G
  9. It could be that the use of the adjectival 'super' in superposition has been confusing me. If measurement is the key that defines whether a quantum system is in superposition or not, then what about measured versus unmeasured? Personally I suspect the opposite of Spain is located somewhere in the South Pacific. . .
  10. A few years ago one of my nieces, then aged twelve, asked me what "the opposite of superposition" is. Her question completely stumped me at the time. It still does. I have since considered placeholder answers like: normal position, position, classical position, etc. None of them seem satisfactory, however. This same question (with full quotation marks) also continues to stump Google. NB. I am prepared to be told that the question is nonsensical - that it'll be like asking what the opposite of Spain is, for example. Still, I'm up for it.
  11. Regarding ventilation: this used to be potentially an issue given the room's double glazing. It was necessary to block off the window's trickle vent, this due to the wind persistently recreating Bob Dylan-like harmonica sound-effects with it (worse still, given the prevailing wind direction in this part of the world, the house itself is situated near the top of a south-west facing hill with an uninterrupted view of the horizon). The room isn't particularly dusty, although I will now give it an early spring clean. Allergens remain an unknown at present. On the other hand, I do keep the door open at all times, beyond which is a landing which in turn leads to the stairwell. Meanwhile, the ambient humidity level outside the house is 91% at the time of writing, while the temperature is just 2 degrees Celsius. This high humidity count is actually fairly typical in this part of England. What is confusing, though, is the relationship between temperature and humidity. Do people living on the equator who routinely endure both high temperatures and (say) 100% humidity levels suffer from respiratory problems? Or have they adapted to these conditions in the same way that people living at high altitudes have adapted to low oxygen levels due to the thinness of the atmosphere? Extremely puzzling, that. studiot, I note with interest your own high humidity readout. To reiterate: in respiratory terms I really do feel better for having a count of between 65% ~ 70%. I just wish I knew why.
  12. This is from a person who spends several hours a day word-processing in a smallish upstairs boxroom (2.4m x 3.8m) that faces south-west. The room is centrally heated (20 C) and efficiently double-glazed. For sometime now I have suffered from minor, but persistent respiratory problems, stuffy nose, throat-clearing issues. I also have chronic sinusitis, which I plan to do something about just as soon as Covid-19 finally abates. . . whenever that might be? Meanwhile, these respiratory problems have all but vanished since using a humidifier. It seems that it more than compensates for the room's dryness, which may be due in large part to running two PCs, plus a UPS battery system and other electronics. What is puzzling, though, is that the full benefits only arise when the room's humidity levels hover around the 70% mark. This must be mentioned because it's routinely cited that optimum humidity levels should be between 30% ~ 50%. This is waaay too low for me, which means either I'm an exception (i.e. a naturally 'wet' person) or else I'm failing to understand something fundamental about humidity. Any comments/suggestions welcomed. Apologies for the repeated usage of the first person singular. Unfortunately the issues related above apply particularly to the poster.
  13. It should bother you - if only because the "wilfully ignorant" tend to vote into office the kind of dickheads who are currently doing the rest of us NO favours whatsoever. Anyone care for a re-run of 2017? Then there's this. . . https://www.nytimes.com/2019/12/28/climate/trump-administration-war-on-science.html
  14. This is a valid point. . . as far as it goes. It's just that it's not enough any longer. In the age of the internet it's no longer a matter of leading a person to a book; rather it's a case of leading the book to the person.
  15. Many thanks for the link. Yes, the fact that both are just opinion pieces illustrates how so-called "truthers" like Mark Steele can patrol their chosen agendas the way they do. This is more an internet problem than a purely science-based one. Still, speaking as a layperson/armchair observer here, it might be helpful if scientists took on Steele and his ilk more directly. There's no chance of getting such folk (and the majority of their camp followers) to alter their views by reasoned debate, of course - not when these views are buttressed by emotional convictions. All the same it would surely help the many undecided, even the merely disinterested. Just an observation.
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