4 ms·

Random Numbers from Astronomical Imaging (2005)

53 points by astrodev 9y ago

matt_wulfeck 9y ago
> Abstract This article describes a method to turn astronomical imaging into a random number generator by using the positions of incident cosmic rays and hot pixels to generate bit streams. We subject the resultant bit streams to a battery of standard benchmark statistical tests for randomness and show that these bit streams are statistically the same as a perfect random bit stream. An honest question, but couldn't the exact same results be achieved with a simple USB webcam pointed at... well, anything?
- altrego99 9y ago
  In both cases you'd need to know some properties of the distribution to get a random bitstream. Which pixel would you be looking at? Below what threshold would you call it a 0 rather than 1? How long till you can confidently say next reading will be uncorrelated? I don't know how the astronomical imaging solved these (and TBH cosmic ray scanning seems a bit overkill to me too).
  - greglindahl 9y ago
    USB webcams get hit by cosmic rays, too. This paper is interesting because it's not just looking at the low bits of a normal image, but rather at at exceptional events. It's a different sort of random.
  - eru 9y ago
    Actually, you can get pretty far with randomness extractors with scant assumptions on the properties of the bitstream.
- JshWright 9y ago
  One (fairly niche) advantage of using 'astronomical' entropy sources is that the event generating the entropy took place in the past (likely before you even designed your experiment). This is useful when looking at certain quantum phenomenon, which is notoriously non-intuitive when it comes to observer bias, etc...
  - inlineint 9y ago
    Could you please provide an example of such experiment involving quantum phenomena? Also doesn't the proposition that the act of designing/conducting some experiment and the noise generated by some events that took place in past (but can't be classically observed at the moment of conducting the experiment because the light generated by those events didn't reach the location of the experiment before the moment of finishing the experiment) cannot be correlated contradicts the non-locality of quantum mechanics?
    - nullkraft 9y ago
      Physics Girl on PBS Digital Studios reported on an experiment using this technique. NEW RESULTS! Cosmic Quantum Bell Test https://www.youtube.com/watch?v=i6WxIblKVZI https://www.youtube.com/watch?v=i6WxIblKVZI
      - inlineint 9y ago
        Thank you. So basically the parent comment was talking about experiments for validating quantum non-locality at galactic scales. And the experiment mentioned in your link confirms this non-locality up to the distances of 600 light years, but we want to confirm it for even larger distances and times, that's why there is a need for techniques like the subject of this discussion.
- nickpsecurity 9y ago
  Yeah: https://en.wikipedia.org/wiki/Lavarand https://en.wikipedia.org/wiki/Lavarand Started as a camera looking at lava lamps. Then, focused on pulling stuff from the image sensor itself in darkness IIRC. Another I just found looking for it: https://www.hindawi.com/journals/mpe/2013/285373/ https://www.hindawi.com/journals/mpe/2013/285373/
tarikozket 9y ago
Actually this is what I believe in life :) I believe, seed reference point of the random theory is stars and that's because most of the times astrology is accurate.
bArray 9y ago
Why not just take the least significant bit and build the random stream from that? As the comment from matt_walfeck suggests: > couldn't the exact same results be achieved with a simple USB webcam Random radiation flipping the least significant bit of the CMOS sensor should be enough. If you're really worried about randomness, you can combine several streams (XOR) and get an even distribution of bits.
- jakobdabo 9y ago
  You won't get a perfect (~8 bit per byte) entropy required for a good PRNG just by getting the least significant bit of the CMOS sensor (or an ADC), as it will always have some kind of bias.
  - DamonHD 9y ago
    There are standard techniques to remove (eg DC) bias from such bit streams.
notum 9y ago
This is very interesting, I love exploring all the "weird" sources of entropy such as random number generators based on background radiation (easy to build if you don't mind playing with high voltage), ones based on radio white noise (easily tampered with) and others. However my favorite is probably: a Nokia N9 + a laser pointer: https://www.sciencealert.com/physicists-have-created-a-quantum-random-number-generator-from-an-old-nokia-phone https://www.sciencealert.com/physicists-have-created-a-quant...
- Terribledactyl 9y ago
  You might enjoy this: https://en.m.wikipedia.org/wiki/Lavarand https://en.m.wikipedia.org/wiki/Lavarand
  - notum 9y ago
    I did enjoy that, thanks!
FrenchyJiby 9y ago
Interesting : The book "His Master's Voice" by Stanislaw Lem depicts astronomical imaging tapes as random number generator in use by mathematicians and other professionals, until one of them sues the observatory for a lack of randomness in the tape he received. Turns out the was a signal in there after all, triggering a fascinating scientific investigation (and setting the whole plot of the book into motion)

53 points by astrodev 9y ago

> Abstract This article describes a method to turn astronomical imaging into a random number generator by using the positions of incident cosmic rays and hot pixels to generate bit streams. We subject the resultant bit streams to a battery of standard benchmark statistical tests for randomness and show that these bit streams are statistically the same as a perfect random bit stream. An honest question, but couldn't the exact same results be achieved with a simple USB webcam pointed at... well, anything?

altrego99 9y ago
In both cases you'd need to know some properties of the distribution to get a random bitstream. Which pixel would you be looking at? Below what threshold would you call it a 0 rather than 1? How long till you can confidently say next reading will be uncorrelated? I don't know how the astronomical imaging solved these (and TBH cosmic ray scanning seems a bit overkill to me too).
- greglindahl 9y ago
  USB webcams get hit by cosmic rays, too. This paper is interesting because it's not just looking at the low bits of a normal image, but rather at at exceptional events. It's a different sort of random.
- eru 9y ago
  Actually, you can get pretty far with randomness extractors with scant assumptions on the properties of the bitstream.
JshWright 9y ago
One (fairly niche) advantage of using 'astronomical' entropy sources is that the event generating the entropy took place in the past (likely before you even designed your experiment). This is useful when looking at certain quantum phenomenon, which is notoriously non-intuitive when it comes to observer bias, etc...
- inlineint 9y ago
  Could you please provide an example of such experiment involving quantum phenomena? Also doesn't the proposition that the act of designing/conducting some experiment and the noise generated by some events that took place in past (but can't be classically observed at the moment of conducting the experiment because the light generated by those events didn't reach the location of the experiment before the moment of finishing the experiment) cannot be correlated contradicts the non-locality of quantum mechanics?
  - nullkraft 9y ago
    Physics Girl on PBS Digital Studios reported on an experiment using this technique. NEW RESULTS! Cosmic Quantum Bell Test https://www.youtube.com/watch?v=i6WxIblKVZI https://www.youtube.com/watch?v=i6WxIblKVZI
    - inlineint 9y ago
      Thank you. So basically the parent comment was talking about experiments for validating quantum non-locality at galactic scales. And the experiment mentioned in your link confirms this non-locality up to the distances of 600 light years, but we want to confirm it for even larger distances and times, that's why there is a need for techniques like the subject of this discussion.
nickpsecurity 9y ago
Yeah: https://en.wikipedia.org/wiki/Lavarand https://en.wikipedia.org/wiki/Lavarand Started as a camera looking at lava lamps. Then, focused on pulling stuff from the image sensor itself in darkness IIRC. Another I just found looking for it: https://www.hindawi.com/journals/mpe/2013/285373/ https://www.hindawi.com/journals/mpe/2013/285373/

tarikozket 9y ago

Actually this is what I believe in life :) I believe, seed reference point of the random theory is stars and that's because most of the times astrology is accurate.

bArray 9y ago

Why not just take the least significant bit and build the random stream from that? As the comment from matt_walfeck suggests: > couldn't the exact same results be achieved with a simple USB webcam Random radiation flipping the least significant bit of the CMOS sensor should be enough. If you're really worried about randomness, you can combine several streams (XOR) and get an even distribution of bits.

jakobdabo 9y ago
You won't get a perfect (~8 bit per byte) entropy required for a good PRNG just by getting the least significant bit of the CMOS sensor (or an ADC), as it will always have some kind of bias.
- DamonHD 9y ago
  There are standard techniques to remove (eg DC) bias from such bit streams.

notum 9y ago

This is very interesting, I love exploring all the "weird" sources of entropy such as random number generators based on background radiation (easy to build if you don't mind playing with high voltage), ones based on radio white noise (easily tampered with) and others. However my favorite is probably: a Nokia N9 + a laser pointer: https://www.sciencealert.com/physicists-have-created-a-quantum-random-number-generator-from-an-old-nokia-phone https://www.sciencealert.com/physicists-have-created-a-quant...

Terribledactyl 9y ago
You might enjoy this: https://en.m.wikipedia.org/wiki/Lavarand https://en.m.wikipedia.org/wiki/Lavarand
- notum 9y ago
  I did enjoy that, thanks!

FrenchyJiby 9y ago

Interesting : The book "His Master's Voice" by Stanislaw Lem depicts astronomical imaging tapes as random number generator in use by mathematicians and other professionals, until one of them sues the observatory for a lack of randomness in the tape he received. Turns out the was a signal in there after all, triggering a fascinating scientific investigation (and setting the whole plot of the book into motion)