It does seem a little confusing how to quantify information when the universe 
itself is regarded as a computation.

Some flies buzzing around the horses may make a difference in the horse race. 
If the flies are "erased," then that issue is settled, which seems to count as 
a decrease of uncertainty and therefore as an _increase_ of info. How does one 
arrive at a result for net change of info?

The settlement of questions by imaginary erasure of all 'extraneous' factors, 
elimination of 'details,' "reductive" abstraction, etc., seems to be a basic 
working step for treating a scenario under a probability-theoretic viewpoint. 
Would the "real" erasure of those factors count in the same way as an increase 
of information? It seems like an increase of info at least in the case where we 
do remember the real things that we've erased or annihilated. Anyway, trying to 
arrive at a result for net change of information seems to require adopting some 
"meta" viewpoint, though I don't know, I'm not well versed in information 

On the other hand, when we treat things as being samples & surfaces of more 
opaque things even when we do know somewhat about what is or isn't under those 
surfaces, then factors/details which have been settled tend to get put into 
question or "veiled" such that it's uncertain what difference they make, and 
that's a decrease in info which seems to be a basic working step for treating a 
scenario under a statistical-theoretic viewpoint. When we feign ignorance about 
how things will be affected, that's an imaginary addition possible factors. 
Would a real adding of possible factors, uncertainty, count as a decrease in 
info? It seems like a decrease of info at least in the case where we do 
remember that those factors weren't previously there.

Are these problems real? Maybe a universe doesn't allow for change of 
information that requires some sort of "meta" viewpoint to calculate. On the 
other hand, maybe I just don't know what I'm talking about.

Best regards, Ben Udell

----- Original Message ----- 
From: "Wei Dai" <[EMAIL PROTECTED]>
To: <>
Sent: Sunday, April 09, 2006 3:11 AM
Subject: why can't we erase information?

If we consider our observable universe as a computation, it's rather 
atypical in that it doesn't seem to make use of the erase operation (or 
other any operation that irreversibly erases information). The second law of 
thermodynamics is a consequence of this. In order to forget anything 
(decrease entropy), we have to put the information somewhere else (increase 
entropy of the environment), instead of just making it disappear. If this 
doesn't make sense to you, see Seth Lloyd's new book "Programming the 
Universe : A Quantum Computer Scientist Takes On the Cosmos" for a good 
explanation of the relationship between entropy, computation, and 

Has anyone thought about why this is the case? One possible answer is that 
if it were possible to erase information, life organisms would be able to 
construct internal perpetual motion machines to power their metabolism, 
instead of competing with each other for sources of negentropy, and perhaps 
intelligence would not be able to evolve in this kind of environment. If 
this is the case, perhaps there is reason to hope that our universe does 
contain mechanisms to erase information, but they are not easily accessible 
to life before the evolution of intelligence. It may be a good idea to look 
out for such mechanisms, for example in high energy particle reactions.

However I'm not sure this answer is correct because there would still be 
competition for raw material (matter and energy) where intelligence can 
still be an advantage. Anyone have other ideas?

You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To post to this group, send email to
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at

Reply via email to