Does perfect white noise really exist?

Ben wrote:
> So you do not dispute that it actually exists in the universe, do you?
> inspite of the fact that "pure white noise" will need an infinite BW?

The phrasing of your question would be appropriate if thought I believed 
that white noise exists. I assume that's a misreading; in any case, I 
don't. Your top posting makes it difficult to show my remarks coherently 
in context, so I'll quote here:

"Ben wrote:
 > OK, here is a rephrase:
 >
 > We now know for sure that "pure white noise" is a hypothetical entity,
 > used for mathematical simplicity rather than any practical use.

   ...

"Not quite. Its mathematical simplicity is what makes it practically 
useful."

In short, white noise is a mathematically simple hypothetical 
construction of great practical utility. Does that answer your question?

Perhaps you've studied Strength of Materials. If so, you know how to 
calculate the deflection of a loaded beam. If you remember the 
derivation of the calculation, you'll recall the hidden assumption that 
the beam is undeflected. That assumption comes from the explicit 
assumption that transverse planes through the undeflected beam remain 
parallel throughout the analysis. The analysis yields results accurate 
to a few tenths of a percent at loads that don't cause beam failure.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

Ben wrote:
> ;-)
>
> There goes my theory in the trash can!!! But, yes no harm in
> hypothesizing half of physics and keeping the other half intact!!!

Hey Ben,

I apologize if I was a bit hard on you.

I reexamine my response and I say to myself, "At least
he's trying to reason things out, and that's a very good
thing."

By all means, bring your thoughts and questions, even the
ill-formed ones, here to comp.dsp, and if the old-farts like
me have a little too much heartburn with something, just ignore us.
There are plenty of folks here who will engage you in a positive
and encouraging way.

--Randy

I reexamined your response after sending in mine, and realized that the
first statement

>  > We now know for sure that "pure white noise" is a hypothetical entity,


is not what you contest, rather my premise that

>  > used for mathematical simplicity rather than any practical use.

is what seems whacky since I assumed "mathematical simplicity" to be
mutually exclusive to "practical use"!!!

Partho


 >
>  > We now know for sure that "pure white noise" is a hypothetical entity,
>  > used for mathematical simplicity rather than any practical use.
>
>    ...
>
> "Not quite. Its mathematical simplicity is what makes it practically
> useful."
>
> In short, white noise is a mathematically simple hypothetical
> construction of great practical utility. Does that answer your question?
>
> Perhaps you've studied Strength of Materials. If so, you know how to
> calculate the deflection of a loaded beam. If you remember the
> derivation of the calculation, you'll recall the hidden assumption that
> the beam is undeflected. That assumption comes from the explicit
> assumption that transverse planes through the undeflected beam remain
> parallel throughout the analysis. The analysis yields results accurate
> to a few tenths of a percent at loads that don't cause beam failure.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF

Ben wrote:

>     ... I assumed "mathematical simplicity" to be
> mutually exclusive to "practical use"!!!

That's not a good assumption. Mathematical simplicity makes many 
idealizations suitable for practical calculation. Can you imagine 
studying statics without the unreal idealization of "rigid body"?

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������