Hi Dave, The formula you quote is the correct one.
The one quoted from the sundial "delta tau = square root(delta t -((V(t)/c)))" is not correct since there is no square and the t is inside the root ... The correction for Aberration of the starlight is delta t = v/c. See e.g. http://www.phy6.org/stargaze/Saberr.htm The traditional analogy to explain the effect is the umbrella & rain: If it is raining and you stand under the umbrella you stay dry. If you walk in the rain with a velocity v and the rain comes down with velocity c, then the apparent angle of the raindrops is given by tan(alpha) = v/c, so your feet get wet when you walk quickly. The same is true when the earth is moving around the sun, so it should have an effect on the sundial time ... Werner -----Original Message----- From: Dave Bell [mailto:[EMAIL PROTECTED] Sent: Tuesday, May 31, 2005 4:31 PM To: Werner Riegler; [email protected] Subject: Re: Relativistic sundial What do you mean by Aberration, Werner? The formula looks close to right for the time dilation effect, as if quoted from memory. I think it was supposed to be "delta Tau = delta t times the square root of (one minus v squared over c squared)". Dave Werner Riegler wrote: >This sounds very interesting. However -- the formula quoted below is >completely wrong in this context and has nothing to do with relativity. >Does it say that it has to do with relativity ? To me it looks more >like a formula for the effect of Abberation. Could you send me the >picture of the dial ? > > Thanks Werner > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Roger Bailey >Sent: Monday, May 30, 2005 7:15 PM >To: anselmo; [email protected] >Subject: RE: Relativistic sundial > >I was surprised recently to see a sundial that has a relativistic time >dilation correction. There is a dial by "Atelier Tournesol" in the >hamlet of Les Vigneaux, Vallouise, Haut Alpes. It is a triangular North >east facing vertical declining on the old presbytery across from the >church clock tower with a pair of corner VD dials. Above the dial is >the equation "delta tau = square root(delta t -((V(t)/c))). Text does >not render it very well but in looks like relativity to me. > >The dial, dated MCMLXXXIX, has both classical and republican hour >markings (decimal hours) so someone has had fun with this dial design. >Picture available on request. SaF catalogue # 0518002. > >Regards, > >Roger Bailey > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] Behalf Of anselmo >Sent: May 30, 2005 1:02 AM >To: [email protected] >Subject: Relativistic sundial > > >Dear all, > >Everybody knows the story of a salesman that, after having been >travelling at a very high speed, discovers that his wrist-watch is >delayed respect the rest of the world's, isn't it? > >But what if his wrist-watch >were a sundial? Obviusly it can't >be delayed so... what has happened? > >Anselmo > > >- > >- > >- > > -
