Yes, Ligeti was very much alive when 2001 was filmed.  Actually, he died 
in 2006, 5 years after they found the monolith. 
http://en.wikipedia.org/wiki/Gy%C3%B6rgy_Ligeti

Mike Richter wrote:
> Steven C. Barr(x) wrote:
>> ----- Original Message ----- From: "Roger and Allison Kulp" 
>> <[log in to unmask]>
>>> Classical Music Imperiled: Can You Hear the Shrug? By EDWARD ROTHSTEIN
>>>
>> It is also worth noting that the reason classical music was often 
>> heard in
>> film scores (or in music recommended to accompany silent films...) was
>> simply the fact that most of it was written before the era of 
>> performing-
>> rights groups and publisher royalties...
>>
>> Steven C. Barr
>
> Even allowing for the overstatement - surely, only *one* of the 
> reasons - the above is at best questionable. "Classical" music has 
> been composed for and used in film from the era of silents through 
> 2001 A Space Odyssey and beyond. Of course, there is always question 
> about which music is classical. However, much of the music used is in 
> copyright even if not composed explicitly for the film.
>
> Needless to say, 'silent' films were not silent. Many had explicit 
> scores such as those composed by Charlie Chaplin and the masterworks 
> of Prokofiev for Eisenstein. Of course, most relied on improvisation 
> from the organist who would be more likely to use standard themes than 
> to quote either classical or popular tunes.
>
> Mike