Random Numbers from Astronomical Imaging (2005) | Hacker News Reader

Random Numbers from Astronomical Imaging (2005)

cambridge.org

53 pointsastrodev17 comments

> 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?

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).

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.

Actually, you can get pretty far with randomness extractors with scant assumptions on the properties of the bitstream.

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...

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?

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

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.

Yeah:

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/

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-quant...

You might enjoy this: https://en.m.wikipedia.org/wiki/Lavarand

I did enjoy that, thanks!

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)

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.

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.

There are standard techniques to remove (eg DC) bias from such bit streams.

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.

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