"Evanescent" is close, though is really means vanishing and nearly imperceptible.  
David

--------------------------------
David Alan Grier
Past President, IEEE Computer Society 

http://video.dagrier.net
http://erranthashtag.dagrier.net

Associate Professor, International Science & Technology Policy  
Elliott School of International Affairs 
George Washington University
grier@gwu.edu








On Oct 30, 2014, at 9:12 AM, Ceruzzi, Paul <CeruzziP@si.edu> wrote:

I heard it from Mike Williams, when he had his professor of computer science hat on! Here’s how he said it:
 
If it is there, but you can’t see it, it is transparent.
If it isn’t there, but you see it, it is virtual.
If it is there, and you see it, it is real.
 
For the purposes of symmetry, what if something is not there and you can’t see it?
 
Paul
 
From: members-bounces@sigcis.org [mailto:members-bounces@sigcis.org] On Behalf Of Thomas Haigh
Sent: Wednesday, October 29, 2014 7:01 PM
To: members@sigcis.org
Subject: [SIGCIS-Members] Virtuality versus transprency -- trying to locate a quote about the difference
 
Hello SIGCIS,
 
I am trying to locate a quote I remember reading circa 1998. It is something along the lines of “Something virtual isn’t really there but looks as if it is. Something transparent is really there but looks as if it isn’t.” That is of course the computer science sense of transparency as making the work of software invisible a user or process – for example how the network stack shields applications from whatever network media the data is travelling over to present the illusion of a connection.
 
Google is not helping me. Does anybody know the source and correct wording?
 
Thanks,

Tom
_______________________________________________
This email is relayed from members@sigcis.org, the email discussion list of SHOT SIGCIS. Opinions expressed here are those of the member posting and are not reviewed, edited, or endorsed by SIGCIS. The list archives are at http://sigcis.org/pipermail/members/ and you can change your subscription options athttp://sigcis.org/mailman/listinfo/members