Re: [SystemSafety] Software reliability (or whatever you would prefer to call it)

From: Yiannis I Papadopoulos < >
Date: Tue, 10 Mar 2015 12:14:40 +0000


Hi David! Thanks for the amusing post :)

"I hate to destroy your comfortable illusion, but a long time ago (in a galaxy quite close to where you live) the ERNIE machine that decided who won the weekly and monthly premium bond draw in the UK used the random noise in a particular kind of diode as the source for the random numbers. I believe the noise is a quantum effect."

Does this quantum effect show that there is "randomness" in the world? If quantum phenomena caused real randomness then the world would be fairly unpredictable. But still, the laws of physics are pretty deterministic and the macro-world is pretty predictable.

On a more mundane level, unfortunately I have not seen yet much "real randomness" when I program, analyse, test and verify code. For example I have never seen an "if" mutating into a "for" or a stamement that is either an "if" or a "for" depending on the observer :). Admittedly it would have been fun, but never happened nevertheless.

In any case, if you really believe that quantum mechanics introduces real randomness in the macrocosm, and has impact on this discussion, then I am really looking forward to reading your paper about how to incorporate quantum mechanics in the assessment and verification of systems and software (happy to coauthor too :)

Thanks and have a good day! :)  

Yiannis

-----Original Message-----
From: David Haworth [mailto:david.haworth_at_xxxxxx Sent: Tuesday, March 10, 2015 11:42 AM
To: Yiannis I Papadopoulos
Cc: Nick Tudor; systemsafety_at_xxxxxx Subject: Re: [SystemSafety] Software reliability (or whatever you would prefer to call it)

Hi Yiannis,

> (... no Heisenberg please ... if quantum mechanics introduced any
> real randomness in the world as we know it, we would be in real trouble
> :)

I hate to destroy your comfortable illusion, but a long time ago (in a galaxy quite close to where you live) the ERNIE machine that decided who won the weekly and monthly premium bond draw in the UK used the random noise in a particular kind of diode as the source for the random numbers. I believe the noise is a quantum effect.

https://en.wikipedia.org/wiki/Premium_Bond#ERNIE https://en.wikipedia.org/wiki/Hardware_random_number_generator

I also spent many "happy" hours analysing why a range of radiation monitors produced by the company I then worked for reported that they had failed occasionally. The answer was that the tiny scrap of radioactive material that was built into the Geiger tube in the equipment, that was intended to provide at least one measurable decay event every 3 seconds or so would in reality sometimes not produce anything for 10 seconds or more. What's more, the calculations that we made and the simulations that we ran correlated with the observed phenomenon remarkably accurately.

So in some sense, the randomness introduced by quantum mechanics had a direct effect on my own experience. And quite likely on all those who have won prizes in the premium bond draw :-)

Dave

On 2015-03-10 10:37:33 +0000, Yiannis I Papadopoulos wrote:
> " Software essentially boils down to a string of one's and nought's.
> Given the same inputs (and that always comes from the chaotic
> environment) then the output will always be the same. It therefore
> makes no sense to talk about 'software reliability' "
>
>
> The premise is true but does the conclusion follow?
>
>
> Take the example of throwing a dice.
>
>
> If you know everything about the dice and its environment and apply the
> laws of physics you can determine the outcome. You can be god,
> replicate the exact conditions and you will get the same outcome every
> time (... no Heisenberg please ... if quantum mechanics introduced any
> real randomness in the world as we know it, we would be in real trouble
> :)
>
>
> So, what is the purpose then of talking about randomness, probability
> and statistics to describe such phenomena? I think the answer is that
> it is often the best, sometimes the only way, to reason about complex
> deterministic processes. It is done all the time in science, why not in
> software?
>
>
> --
>
> Yiannis Papadopoulos
>
> http://www2.hull.ac.uk/science/computer_science/our_staff/staff_profile
> s/yiannis_papadopoulos.aspx

> **************************************************
> To view the terms under which this email is
> distributed, please go to
> http://www2.hull.ac.uk/legal/disclaimer.aspx
> **************************************************

> _______________________________________________
> The System Safety Mailing List
> systemsafety_at_xxxxxx

-- 
David Haworth B.Sc.(Hons.), OS Kernel Developer    david.haworth_at_xxxxxx
Tel: +49 9131 7701-6154     Fax: -6333                  Keys: keyserver.pgp.com
Elektrobit Automotive GmbH           Am Wolfsmantel 46, 91058 Erlangen, Germany
Geschäftsführer: Alexander Kocher, Gregor Zink       Amtsgericht Fürth HRB 4886

************************************************** To view the terms under which this email is distributed, please go to http://www2.hull.ac.uk/legal/disclaimer.aspx **************************************************
_______________________________________________ The System Safety Mailing List systemsafety_at_xxxxxx
Received on Tue Mar 10 2015 - 13:14:49 CET

This archive was generated by hypermail 2.3.0 : Fri Feb 22 2019 - 04:17:07 CET