Timothy Murphy wrote:
> On Friday 16 May 2008 03:29:28 pm paul at clubi.ie wrote:
>>>>> This is pure wishful thinking. You are saying that if _you_ cannot
>>> work out what the next number is, because the system is so
>>> complicated, then the sequence must be random.
>>>>>> You are much, much better off with a mathematical function f(n) mod
>>> m which people have studied, and found no patterns in the output.
>>>>> So an RNG based on study and understanding of the physical world is
>> "wishful thinking", but based on periodic functions, that's fine.
>>>> This sounds like domain snobbery to me. ;)
>>>> f(n) mod m is not necessarily (or even usually) periodic.
>> Anybody who pays real money for a black box
> that is supposed to output random numbers through quantum theory
> is very gullible, in my view.
>> It is one thing to understand quantum mechanics,
> and quite another to construct a device that uses it.
>> You might as well say that if you understand thermodynamics
> you can construct an efficient car engine.
>> Ps Do you know about quantum entanglement?
>>>You don't need to know anything about quantum mechanics to make a USB
key with zener and ADC in it. You can read it for the next 10,000,0000
years (at 1G samples / sec) and never see a pattern nor predict what the
next number will be. Does it matter how often you read it? Think of a
dice thrown continuously. It doesn't make any difference when you
look or how often you look, it has no memory. The odds of a six on any
one throw are 1/6th. But you can never know what a previous or later
throw is without actually viewing the event.
"White Noise" is a bit of red herring. All thermal noise sources have
a curved frequency distribution like a skewed bell. The curve
peak moves with temperature (observable by varying voltage on a
filament bulb.). This does not make the signal less random. In fact we
don't much care about the frequency distribution.
This is far off the original topic. But interesting. Also interesting is
that Humans have no instinct about probability. What seems reasonable is
usually wrong. Betting on a lottery number that has come up or hasn't
come up (or roulette numbers) makes no practical difference. A random
walk can be very very long. But since there is always a bias in favour
of casino ( the number you can't bet on) and the lottery a percentage is
kept, the gamblers are the losers. The balls, wheel, dice have no memory.
Maintained by the ILUG website team. The aim of Linux.ie is to
support and help commercial and private users of Linux in Ireland. You can
display ILUG news in your own webpages, read backend
information to find out how. Networking services kindly provided by HEAnet, server kindly donated by
Dell. Linux is a trademark of Linus Torvalds,
used with permission. No penguins were harmed in the production or maintenance
of this highly praised website. Looking for the
Indian Linux Users' Group? Try here. If you've read all this and aren't a lawyer: you should be!