Re: Theoretical limit for loud music??

From: Kevin Aylward (salesEXTRACT_at_anasoft.co.uk)
Date: 09/04/04 

Date: Sat, 04 Sep 2004 12:00:34 GMT

Guy Macon wrote:
> Kevin Aylward <salesEXTRACT@anasoft.co.uk> says...
>>
>> Guy Macon wrote:
>
>>> SPL is a function of the
>>> velocity and the mass of the medium.
>>
>> Yes, but technically its the momentum. Light has pressure, but no
>> "rest mass".
>
> I thought we were talking about air approaching lightspeed.
>
>>> Unlike the negative limit
>>> which is hard clipping at zero pressure (vacuum), approaching
>>> the positive limit is a matter of pouring more and more energy
>>> into attempting to accelerate the medium, only to have that
>>> energy turn into mass rather than velocity at the E=MC2 rate.
>>> This additional mass allows higher pressures, and can approach
>>> infinity if you pump enough energy in.
>>
>> That's not quite how it works though. This "mass increase" bit is a
>> bit of a misnomer. Mass itself, doesn't actually increase. No
>> professional physicist uses the concept at all, well, accept when
>> writing popular paperbacks.
>
> News to me - but then again, I am an eclectronicsite, not a
> Physicsoid...
>
> http://www.google.com/search?q=physics++%22mass+increases%22

Sure, you'll find many references to "mass increase", but this is
"inertial mass", a somewhat outdated term that is not very useful for
serious work. For example, one gets into the bother of longitudinal mass
and transverse mass, which are different. Mass is an invariant in
Relativity.

have a look at
http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

or maybe http://www.anasoft.co.uk/physics/gr/index.html :-)

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
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