[time-nuts] Thunderbolt stability and ambient temperature

Rex rexa at sonic.net
Thu Jun 11 21:53:01 EDT 2009


J. Forster wrote:

>It has nothing to do with this.
>
>A long (length >> width) bar can simply be modeled as a long ladder of
>series resistors's and capacitors to ground:
>
>---zzz---zzz---zzz----  ...  ---zzz---
>   _|_   _|_   _|_              _|_
>   ___   ___   ___              ___
>----| ----|-----|-----  ...  ----|-----
>
>If you put a rectangular pulse in the left end, it will emerge later and
>very much rounded at the right end.
>
>Either do the math or simulate it in Spice or with a handful of R's and
>C's and a pulse generator and scope.
>
>No inductors needed. PERIOD. That model fully accounts for your
>observations with the bar heated at one end.
>
>-John
>
>=================
>
>  
>

Ok, but isn't that propagation rate constant? Obviously, the heat from 
the hot end will eventually propagate with some attenuation to the cold 
end. My observation was that shoving cold into the hot end seems to 
accelerate the propagation of heat toward the cold end. This model won't 
show that effect, will it?

This would be a double step something like this:

   |---
   |   \
---|    \        ----> + time
         |      /
         |----|

That 2nd opposite step won't make the first pulse propagate faster or 
with more apparent intensity, will it?

-Rex

>
>  
>
>>In message <4A309B30.7000400 at sonic.net>, Rex writes:
>>
>>    
>>
>>>My observation, from doing this
>>>several times, is that the cold water quickly absorbes heat from the red
>>>end, but also seems to chase a lot of the heat quickly up toward the
>>>cold end, making the bar rapidly uncomfortable to hold.
>>>      
>>>
>>I've seen the effect you describe explained in an article somewhere,
>>very likely New Scientist or SciAm about five years ago.
>>
>>When you rapidly heat or cool metals, very often changes in crystal
>>lattice structure is involved some of them resulting in quite drastic
>>changes to volume.
>>
>>Heat is essentially atoms wiggling about, and when you change the
>>modes of freedom for the atoms, they may have to wiggle harder.
>>
>>--
>>Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>>phk at FreeBSD.ORG         | TCP/IP since RFC 956
>>FreeBSD committer       | BSD since 4.3-tahoe
>>Never attribute to malice what can adequately be explained by
>>incompetence.
>>
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>>
>>    
>>
>
>
>
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>  
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