Wouldn't the model fit reality better if it were based on biological analogies instead of the raw physics of energy? I recognize there's a desire here to put some controls on one's own equipment ("I don't want to receive spam if I don't want to") and that physics provides the conceptual lever to argue in favor of the desired controls. Biological systems are a poor choice for grained control by people who like to change their minds. But the Internet really is more like an ecology with its own complex notion of "emergent order" than a simple physical process that must obey conservation laws in some narrow fashion. Trees obey physical conservation laws, but they don't exchange micropayments with soil, air, and Sun to ensure the balance is preserved. As things get out of balance, trees die. Other entities flourish. I can't imagine the mechanism by which very precise access charging and cost recovery mechanisms would replace the current "free" model. As we all know, it's not really "free." Information is published and made available because the vendor needs to distribute it and finds the Internet to be a cheap way to make it available. Many vendors exchange information and entertainment for your attention to a commercial message. As long as there are unmetered 'Net resources (and they're unmetered for a plethora of reasons) you'll never get rid of free riders. I think you have to choose between the relatively lawless open world or an enclave where you bar the door with your favorite security measures. You allow spam as long as you allow uninvited guests. And what is cypherpunks but a continuous party of uninvited guests? Regarding these micropayment machines, I think it would be interesting to identify some existing, widely used, real world analogues to them: how big/small are individual transactions, how much money can you securely collect, how much does the mechanism cost to deploy and maintain, how hard is it to attack, etc. Gumball machines? Pop machines? Pay phones? I'm not sure there *is* a real world analogue. Rick. smith@sctc.com secure computing corporation