>From: Stathis Papaioannou > >Not at all. There is a *huge* difference between what is possible in theory >and what is possible practically. A person wearing down a mountain with his >fingers is a practical impossibility, but there is nothing in the laws of >physics making it a theoretical impossibility. A person flying to Alpha >Centauri in 5 minutes is logically possible, but the laws of physics make >it theoretically impossible. A person being simultaneously taller than >180cm and shorter than 170cm is a logical impossibility. These three >examples for everyday purposes are equally unlikely to happen, but they are >fundamentally different from a philosophical standpoint. In the case of >classical teleportation, there is nothing in the laws of physics making it >theoretically impossible, and it is certainly not logically impossible. >Time travel is much more dubious: it may be a physical impossibility, and >it may even be a logical impossibility. >
Thank you for a very clear explanation of these 3 theoretical/practical/logical possibility differences. I remember I saw some papers before saying that time travel is theoretically possible, although it remains an open question. It's like teleportation. Maybe you can demonstrate with 1 or 2 particles in QM. But it's another very different thing when we are talking about human beings (or simple animals). Maybe other very knowledgeable prof. (like "scerir"???) in this list can provide useful ref. Thanks. WC. _________________________________________________________________ Get 10Mb extra storage for MSN Hotmail. Subscribe Now! http://join.msn.com/?pgmarket=en-hk --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---
