On Saturday, March 10, 2018 at 8:24:25 PM UTC-6, Bruce wrote: > > From: Russell Standish <li...@hpcoders.com.au <javascript:>> > > > On Sun, Mar 11, 2018 at 10:17:01AM +1100, Bruce Kellett wrote: > > > > My feeling is that we observe that the world has certain symmetries, > then we > > design our theories to reflect these symmetries, because theories that > > incorporate the observed symmetries work better. Since the starting > point is > > observation, we have some prospect of learning something other than the > > nature of our thought processes. > > > > Bruce > > My claim is that there are always symmetric theories. Assuming some > horrible > non-symmetric world, we can make a symmetric theory by a suitable > transformation of variables - in rather the same way we can see a > computation in a rock by a suitable transformation of variables. > > > I think that in general it requires a little more than just a > transformation of variables. If we fail to see rotational symmetry in the > world around us (same laws in all directions), then we would have to > postulate some oriented field, or some interaction that depended on > position and/or direction. To do it by a transformation of variables you > would require the variables themselves to reflect this non-symmetric field. > > > What do you say to the proposition that evolution might have equipped > us with the facility to see those symmetries "intuitively", since it > makes computing things about the world easier? > > > I don't think that actually changes anything -- what that means is that > those symmetries existed in the world, and evolution took place in the > context of those symmetries. So it is anything but an arbitrary imposition > by our minds on a non-symmetric world. > > > Of course it's not > quite so simple, as naive physics had things coming to a stop if you > remove the force, and heavier things falling faster than light things, > but still it probably came close enough that science could refine > observations into the symmetries we see today. > > > Symmetries such as translational and rotational invariance are > sufficiently non-obvious in our friction-dominated world that it took > millennia for it to become clear that the laws of physics actually > respected those symmetries. And even longer for Emmy Noether to recognize > the connection between symmetries and conservation laws. > > Bruce >
These are standard ideas about symmetries. This does not mean these are the only types of symmetries that exist. There are other types of symmetries, such as those with quotient groups and spaces. Similarly there are other types of moduli as well beyond gauge moduli spaces associated with POVI. LC -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
