🚀 go-pugleaf

In article <1993Jan6.063633.15257@athena.mit.edu> redingtn@athena.mit.edu (Norman H Redington) writes:
>In article <1993Jan5.225833.29067@asl.dl.nec.com>, terry@asl.dl.nec.|> 
>|> So again, has sonoluminiscence _already_ been solved, or not?
>|> 
>|> 
>|> 				Cheers,
>|> 				Terry Bollinger
>
>Doesn't Julian Schwinger say it's the dynamical analogue of the
>Casimir effect?

     Just curious.  What meaning is assigned to 'the dynamical analogue
     of the Casimir effect'?  I don't really see any place for the 
     Casimir effect or an analogue in the process.  This isn't exactly
     a subtle indication of zero-point energy.  Are you sure it
     wasn't a joke?  

     As far as Terry's post that I apparently did not reach this site, no it 
     has not exactly been solved in detail to my knowledge, however there
     are recent strong experimental and theoretical indications as to the 
     mechanism for the so-called 'stable cavitation'.  The mechanism is a 
     strong shock being shed into the vapour bubble after
     the bubble begins contracting.  About seven other possible mechanisms
     of various stripes are mentioned in Young's book on cavitation
     (appropriately entitled 'Cavitation'), a good book I'd recommend 
     to anyone interested in cavitation.  

     I was curious, so I looked at UNC (they apparently received Terry's
     post) and the full question involved the timing of the flashes.  
     Barber and Putterman's, in their 28 December PRL article,
     (again PRL: 69:3839 (1992)) measure the bubble radius of 'stable
     cavitation' against time and sonoluminescence.  They
     find that the the SL is 'clearly emitted at or near the moment
     of collapse' (Figure 1).

     Detailed measurements indicate that a roughly 40 microsecond
     period bubble sonoluminesces roughly 4 microseconds after reaching
     maximum radius (and the bubble surface velocity reaches Mach 1 about 10
     nanoseconds before reaching its minimum radius, Figures 3 and 4).  
     This would seem to indicate that the shock 'slow(s) down the collapse 
     of the bubble' and that it is, in fact, a shock.  I have seen a 
     very recent preprint that theoretically describes the first stages
     of this shock shedding process.

                             dale bass
-- 
C. R. Bass                                          crb7q@virginia.edu        
Department of Wildebeest
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