Speed of Light: A universal Constant?
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From: bz on 26 Jun 2005 20:11 H@..(Henri Wilson) wrote in news:t0eub1hpcakkobuqmr4es4skmjtjlt2957(a)4ax.com: > On Sun, 26 Jun 2005 16:23:07 +0000 (UTC), bz > <bz+sp(a)ch100-5.chem.lsu.edu> wrote: > >>H@..(Henri Wilson) wrote in >>news:sv6tb1p8jmhh8n2lmi2eb044igt0s1kqki(a)4ax.com: >> > >>>>> >>>>> "Delta Cep is one of the few easily-visible variables, its magnitude >>>>> changing from 3.5 to 4.3 and back over an amazingly regular period >>>>> of 5 days 8 hours 47 minutes and 32 seconds, the star acting like a >>>>> natural clock. " >>>>> >>>> >>>>The data would seem to indicate that the author of the phrase quoted >>>>might have waxed a bit too much about the regularity of the waining of >>>>Delta Cep. >>> >>> He wouldn't say it acted like a clock if it wasn't pretty stable. >>> You can look at any long term pixel curve on the britastro site and >>> see that most star curves appear dead constant over many years. >> >>The degree of regularity seems to have been over emphasized. >>Dead constant over many years seems to mean that when the data is >>collected and averaged over many years the fit is not TOO bad. >>However the degree of fit should have been reported. > > Here is another reference: > http://weblore.com/richard/ru_cam_ex_cepheid_star.htm > > "Cepheids are known for their precise variability which can be measured > to a fraction of a second." 'can be measured to a fraction of a second' does not necessarily mean 'is constant to a fraction of a second'. There is no question that some cepheids are 'regular' for some period of time. There is also no question that most, if not all cepheids show some variations. There is a question as to whether some people seem to have exaggerated the regularity of cepheids. He specializes in positional astronomy. http://weblore.com/richard/ > > You cannot run away from the truth forever, Bob. I am searching for truth, Henri. >>> I have another theory about cepheids anyway. >>> I still reckon they are largish hot stars orbitted (e=~0.25) by a WCH >>> or neutron star. >>> They experience very large tidal distortions, giving them an >>> ellipsoidal shape. That causes their effective area facing us to vary >>> in synch with the orbit period. Consequently, the majority of the >>> brightness variation might not be due to the BaT after all. >> >>Each theory has its consequences. >> >>Double stars such as you describe are known to exist but they exhibit >>characteristics quite different from cepheids. > > I am pretty certain the above type of star in elliptical orbit and in > tidal lock would exhibit a cepheid like brightness variation. Cepheids show some distinctive characteristics, such as rapid cyclic shifts in stellar type. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+sp(a)ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
From: Arthur Dent on 26 Jun 2005 20:20 Egads, YBM, you STILL can't spell "prove" after all this time. Have a nice day.
From: YBM on 26 Jun 2005 20:23 Henri Wilson wrote : > Cepheids are largish stars that have a WCH (Wilson, cool, heavy) or neutron Wilson, you are not cool, but you are quite heavy.
From: Arthur Dent on 26 Jun 2005 20:25 Henri Wilson wrote: > On Sun, 26 Jun 2005 14:46:40 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> > wrote: > > >H@..(Henri Wilson) wrote in > >news:tl8tb152v0gn26qdip73peho1jk5gphsti(a)4ax.com: > > > >> No it isn't. The beam AS A WHOLE remains vertical. Draw the bloody thing > >> if you don't believe me. H, calm down. bz is accepting the vector addition of velocities. AD.
From: YBM on 26 Jun 2005 20:37
Arthur Dent a ýcrit : > Egads, YBM, you STILL can't spell "prove" after all this time. You haven't still got the point between closing velocity and relative velocity, have you ? |