Summary and General Discussion 375 



not been answered as yet. They are related to the amount of 

 information necessary to transmit or to organize one unit of 

 information. As you know, it is not possible to transmit information 

 if there is not a previous amount of information available as a 

 storage unit. So, the first question is: How many units of infor- 

 mation do we need as a minimum to store one unit of information? 

 The second question is: How much energy is necessary to organize 

 one unit of information? The third question is: How much energy 

 is necessary to transmit from one point to another the same unit 

 of information? 



Warren S. McCulloch (Cambridge, Massachusetts): Do the 

 first two questions amount to how much information you have to 

 have to make another unit of information? This is one of the nasty 

 cjuestions that is puzzling us at the present time. There is a way 

 of approaching it, but no one is happy about it. You cannot say 

 in a simple way, "How much for unit?"; but you can ask — and 

 it is the famous question put by John von Neumann — "How 

 much of a computing machine do you have to have for that 

 computing machine to make more?" This is the same question; 

 you have the problem of the generation of a computer, and it 

 does not matter whether you make it formally or make it in hard- 

 ware. The actual problem is that of starting with no form. This 

 means starting from noise, and from noise it is hard to get anything, 

 to generate any form. The answer is that nobody knows how much 

 information you need. 



Gerard: What about the second question on the energy for 

 transmitting the unit of information? 



McCulloch: With regard to the last question, as small an 

 amount of energy as you can get in one packet can carry one bit. 

 The limit is strictly that of the physics. 



Kit: I wonder if this question is not too general. Should we 

 not be thinking about the kind of information that we are storing, 

 transmitting, and replicating? I think estimates could be made 

 of the amount of energy needed to replicate a DNxA molecule. 

 Also, one can measure the amount of energy consumed by a 

 bacterial cell during the replication of the DNA of a phage. This 

 measured value will be greater than the amount needed for phage 

 DNA synthesis and presumably will be an upper limit of the 



