Speed of Light: A universal Constant?
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From: David Evens on 15 Jun 2005 05:12 On Mon, 13 Jun 2005 00:26:23 GMT, H@..(Henri Wilson) wrote: >On Sun, 12 Jun 2005 21:33:22 +0200, "Paul B. Andersen" ><paul.b.andersen(a)deletethishia.no> wrote: >>The Ghost In The Machine wrote: >>> In sci.physics, Paul B. Andersen >>> <paul.b.andersen(a)deletethishia.no> >>> wrote >>>>>On Thu, 09 Jun 2005 15:01:53 +0200, "Paul B. Andersen" >>>>><paul.b.andersen(a)deletethishia.no> wrote: >>>>> >>>>>>A star is basically a spherical black body emitting >>>>>>a black body spectrum. So the emitted power per surface >>>>>>area is W = sigma*T^4, sigma = Stefan-Boltzmann constant. >>>>>>When the temperature and emitted power is known, >>>>>>the surface area and thus the diameter of the star can >>>>>>be calculated. >>> >>> >>> Assuming, of course, that a star is in fact a spherical >>> thermal black body. (I'd say that's a fairly safe assumption, >>> myself. :-) >> >>It will not be strictly spherical if it is rotating, >>of course. >> >>> However, I'd have to look at what photons are >>> emitted from the H -> He reaction, and it may depend on >>> which cycle the star uses.) >> >>The fusion emits gamma radiation. But that happens in >>the core, and these photons do not go far before they are >>absorbed. New photons are emitted - and absorbed. >>It takes in the order of a million years for the energy >>to get from the core to the surface of the star. >>The star radiates its energy as a black body in >>the photosphere. The temperature is what it has to be >>to radiate as much energy as is produced in the fusion. >> >>[..] >> >>>>So we have an invisible star with hundreds of solar masses. >>>>Such stars do not exist. >>> >>> >>> Black holes do. Admittedly, I for one would find a black >>> hole nearly touching a glowing M1- or M2-mass star >>> extremely unlikely without many highly noticeable effects, >>> a la Cygnus X-1. >>> >>> I mention this mostly for completeness. >> >>Then think about this: >>How could a 100 solar mass black hole be created? >>When a black hole is created from a collapsing star, >>its mass will be but few solar masses. >>If such an animal exists, it certainly isn't as >>a component of a binary. >>(But who knows what may lurk in the centre of >> some globular clusters?) >> >>But anyway - as you say - a 100 solar masses black >>hole in the close vicinity of a Cepheid would make >>it presence very obvious. > >Hahahahah! > >What do you think causes the brightness curve to be exactly as the BaT predicts >for a large star orbiting a neutron star or WCH? Not the BaT, since it ignores the effect such a massive body would have on the gases being emitted from the visible star and the radiation that would be released as these gasses were, inevitably, trapped by its more massive companion. >>>>And you think you by repeating "puffing and blowing" over and over >>>>can make it ridiculous that a standing wave has a stable period? :-) >>> >>> >>> Who says they have a constant period anyway? I suspect they slowly >>> change -- *very* slowly, but I don't have the theory handy -- >>> as the hydrogen is converted to helium and the density/characteristics >>> of the star gas change. >> >>The period is NOT constant for eternity. Cepheids are stars which >>have left the main sequence and passes through the instability >>strip of the HR-diagram on their way to their death. >>But we are talking about millions of years on this journey, >>so most Cepheids will appear very regular for the century or >>so we have observed (some of) them. >>Polaris is an exception - the last century happens to be the >>time when it leaves the instability strip. It is hardly >>a Cepheid any more. >> >>> At some point a Cepheid will, quite literally, run out of gas. >>> (Just like all the others, only different. :-) ) >> >>See: >>http://www.astro.livjm.ac.uk/courses/one/NOTES/Garry%20Pilkington/loc.htm >>Specifically the animated figure showing a star's journey >>from the main sequence to its death - passing through >>the instability strip twice - and thus being a Cepheid twice. >> >> >>>>The Cepheid RT Aurigae with period 3.72 days, have a maxum >>>>surface velocity 17 km/s. The escape velocity is 200 km/s. >>>>So why would there be "bits of gas flying everywhere"? :-) >>> >>> >>> Well, there would be moving bits of gas, anyway. I'll admit to >>> wondering whether we can detect the movement with a sufficiently >>> sensitive spectroscope. >> >>Indeed we can. It is routine. >>The pulsation is measured as a periodic variation in >>the radial velocity of the star. >>How did you think the surface velocity of RT Aurigae >>cited above was measured? >>http://mb-soft.com/public2/cepheid.html > >Paul, have you ever sen a radial velocity curve from a star in elliptical >orbit, with ecc~ 1.5-4 and the the right yaw angle to create brigthtnees curves >according to BaT principles? > >> >>Paul > > >HW. >www.users.bigpond.com/hewn/index.htm > >Sometimes I feel like a complete failure. >The most useful thing I have ever done is prove Einstein wrong.
From: bz on 15 Jun 2005 08:28 H@..(Henri Wilson) wrote in news:0spua15326hoccjg7u2edghs9401ujgqj8(a)4ax.com: > On Tue, 14 Jun 2005 08:53:16 +0000 (UTC), bz > <bz+sp(a)ch100-5.chem.lsu.edu> wrote: > >>H@..(Henri Wilson) wrote in >>news:p1fsa1pt24bmi2c83ha9t314o9pm1snhdf(a)4ax.com: >> > ..... >>> Orbit diameter depends on the mass of the other object. >>> >>> Bob, my only concern was the apparent rate of movement, the angular >>> velocity of something in a 1 day orbit. The sun doesn't appear to move >>> very fast. >> >>The apparant angular velocity due to OUR rotation can not be counted. A >>24 hour orbit will be at a radius of 22,235 miles. >> >>http://en.wikipedia.org/wiki/Orbital_period >>The orbital period depends on the masses involved, the semi major axis, >>and the universal constant G. >>P=2 pi sqrt(a^3/(G(M1+M2))) >> >>solving for 'a' gives >>a=1/(2 pi) 2^(1/3) (P^2 G(M1+M2) pi)^(1/3) >> >>With the mass of the sun as 1.9891E+30*kg and the mass of the earth >>5.9742E+24*kg, a 24 hour orbit is at 2.928E+6*km and the diameter of >>the sun is 1.392E+6*km, so it would be theoretically possible for the >>earth to orbit the sun in 24 hours. It would need to move at 213 km/s >>(7.1E-4 c) (assuming a circular orbit) in order to do so >> >>But two stars the mass of the sun would have to orbit each other at >>3.6E6 KM at 268 km/s (8.9e-4 c). > > Look Bob, I am genuinely sorry for causing this confusion. I thought you > had more brains that Andersen. > > I was merely pointing out that ANYTHING orbiting YOU once per day would > appear to move at the same angular velocity as our sun (or moon) does as > it APPEARS TO 'orbit' us. This was purely to illustrate the visual > impression and had nothing to do with the maths of different sized > objects. But apparent angular velocity has NOTHING to do with anything useful. It only confuses what you might have been trying to say with something totally unrelated. It invites an excursion down a dead end. Apparent angular velocity is a dead end that we left behind when we abandoned the model where the heavens rotated around a flat earth. ..... > To somebody standing on Earth, it still APPEARS to move across the sky > at about the same speed as the sun. Do you dispute that? Forget it! you are just making things worse! We are not concerned with those kinds of motion. They have nothing to do with anything you want to use to support your assertions. We do not use apparent motion across the sky to determine relative velocity of distant stars. -- 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: The Ghost In The Machine on 15 Jun 2005 09:00 In sci.physics, David Evens <devens(a)technologist.com> wrote on Wed, 15 Jun 2005 05:10:41 -0400 <1qrva11j9c727tv9mimgo4ikinor08fj30(a)4ax.com>: > On Sun, 12 Jun 2005 21:00:03 GMT, The Ghost In The Machine > <ewill(a)sirius.athghost7038suus.net> wrote: > >>In sci.physics, Paul B. Andersen >><paul.b.andersen(a)deletethishia.no> >> wrote >>on Sun, 12 Jun 2005 21:33:22 +0200 >><d8i2m7$50d$1(a)dolly.uninett.no>: >>> The Ghost In The Machine wrote: >>>> In sci.physics, Paul B. Andersen >>>> <paul.b.andersen(a)deletethishia.no> >>>> wrote >>> >>>>>>On Thu, 09 Jun 2005 15:01:53 +0200, "Paul B. Andersen" >>>>>><paul.b.andersen(a)deletethishia.no> wrote: >>>>>> >>>>>>>A star is basically a spherical black body emitting >>>>>>>a black body spectrum. So the emitted power per surface >>>>>>>area is W = sigma*T^4, sigma = Stefan-Boltzmann constant. >>>>>>>When the temperature and emitted power is known, >>>>>>>the surface area and thus the diameter of the star can >>>>>>>be calculated. >>>> >>>> >>>> Assuming, of course, that a star is in fact a spherical >>>> thermal black body. (I'd say that's a fairly safe assumption, >>>> myself. :-) >>> >>> It will not be strictly spherical if it is rotating, >>> of course. >> >>Of course. But this is presumably a first-order approx... >> >>> >>>> However, I'd have to look at what photons are >>>> emitted from the H -> He reaction, and it may depend on >>>> which cycle the star uses.) >>> >>> The fusion emits gamma radiation. But that happens in >>> the core, and these photons do not go far before they are >>> absorbed. New photons are emitted - and absorbed. >>> It takes in the order of a million years for the energy >>> to get from the core to the surface of the star. >>> The star radiates its energy as a black body in >>> the photosphere. The temperature is what it has to be >>> to radiate as much energy as is produced in the fusion. >> >>There's also the issue of pressure -- which I'd not >>originally thought of applying to the problem. Crudely >>put, the star wants to contract to a point (or near point), >>whereas the fusion wants to explode. Things balance out >>just so, not unlike thermal equilibrium, though presumably >>harder to calculate. >> >>> >>> [..] >>> >>>>>So we have an invisible star with hundreds of solar masses. >>>>>Such stars do not exist. >>>> >>>> >>>> Black holes do. Admittedly, I for one would find a black >>>> hole nearly touching a glowing M1- or M2-mass star >>>> extremely unlikely without many highly noticeable effects, >>>> a la Cygnus X-1. >>>> >>>> I mention this mostly for completeness. >>> >>> Then think about this: >>> How could a 100 solar mass black hole be created? >>> When a black hole is created from a collapsing star, >>> its mass will be but few solar masses. >>> If such an animal exists, it certainly isn't as >>> a component of a binary. >>> (But who knows what may lurk in the centre of >>> some globular clusters?) >> >>Or for that matter at the center of galaxies? However, >>I think you're generally correct; if a 5 M_sun or so star >>is near a 100 M_sun or so black hole, it'll probably be >>ripped apart and eaten -- assuming that the black hole's >>creation explosion didn't simply disperse the gas of the >>companion star somehow in the first place. However, I'd >>have to look regarding said formation, and I know very >>little regarding the actual math beyond Chankdreksahr's >>Limit being about 1.5 M_sun. > > As was previously noted, you don't GET any stars that can colapse to > form a 100-solar mass black hole, because it is phsically impossible > for stars heavy enough to do so to form. The maximum mass for a star > is somewhere between 30 and 50 solar masses. It has been determined, > as well, that even the most massive stars blow off HUGE portions of > their matter when they collapse into black holes. A 30-solar mass > star, for instance, colapsing into a black hole blows off the > equivalent of an entire solar mass just as gamma rays. (This is what > we finally know to be the source of gamma ray bursts, and we can > consider ourselves fortunate to not have any such superheavy stars in > the immediate neighbourhood, since one of these going of with a few > tens kiloparsecs is a bad day for the homeworld.) A good point. Of course it could get even sillier; black holes, presumably, merge. (The conditions would be fantastic to the extreme near so many Cepheid variables, so much so that Ockham's Razor becomes Ockham's Shredder...) A slightly more likely possibility is that the black hole was born amongst a cluster and got *real* hungry -- so much so that it and the "HenryCepheid" are the only two entities left, orbiting around each other. Not likely. [rest snipped] -- #191, ewill3(a)earthlink.net It's still legal to go .sigless.
From: bz on 15 Jun 2005 09:15 H@..(Henri Wilson) wrote in news:1equa11h11huqcdprcjmqbii6peeg00tg5(a)4ax.com: >>> And this obviously explains how the 40 solar diameter delta Cep >>> and a star which hasn't got to be a neutron star at all, >>> can orbit their barycentre in the common period five days. >>>>Delta Cep: >>>>period = 5.366270 days >>>>radius = 41.6 solar radii >>>>mass = 5 solar masses By the way, the above values are for delta Cep, NOT RT Aur. >> >>two stars of 5 solar masses would orbit at 1.9e7 km >>41.6 solar radii is 2.8e7 km, which, as you have noted, is larger in >>than the orbital radius. So the stars would merge. >> >>In fact, in order for one to skim the surface (assuming zero radius for >>it), it would have to have a mass of 5.72 times the mass of delta Cep: >> >>This gives an orbital velocity of 268 km/s or 1.3e-3c >> >>I figure you need a very heavy black hole of at least 50 times the mass >>of Delta Cep. That gives a separation of 1.96 radii, orbital velocity of >>771 km/s or 2.5e-3 c >> >>All of these present a small problem, however, as the actual doppler >>data figures for RT Aurigae show a maximum velocity of 38 km/sec. At 38 >>km/sec, there is no way for the two stars to maintain orbit and they >>will fall into each other. > > That velocity figure is confusing. The RT Aur system is moving away from > Earth at 21 kms/sec..so you must subtract that. > > The maximum radial speed is only 17km/s. That just makes the orbiting stars model more impossible. But the max radial speed away from us (minimum) gets larger, so we should see more subluminal photons than super luminal photons. > >> >>That will make a big splash and, I fear, swamp Henri's model. > > There is known to be a lot of dark matter in the universe. > Apparently, much of it has cepheids orbiting around. Henri, there is NO possible mass that a cepheid could be orbiting in 5.36 days and have a radial velocity of only 21 kms/sec. The larger the mass, the greater the orbit's diameter AND the greater the orbital velocity. When M2 is 3e9 times M1, the orbital velocity reaches c. With an orbital diameter of 1.5e10 km. Obviously I have neglected to take into account the relativistic increase in mass of the star with velocity. While working through some of these formula it became apparent to me that your program lacks a very important feature: A 'sanity check'. The program needs to flag inconsistent values. The orbital velocity, the orbit's diameter, and the mass(es) of the bodies involved, can NOT all be independent. Your program appears to assume that they are. I am sure there are other sets of interdependent parameters that likewise need to be cross checked. This means that one can currently put in values for interdependent parameters that are inconsistent with each other. This explains some of the weird looking curves your program produces. When the user inputs two of the values, the program needs to calculate the third and if that doesn't match what the user is specifying, the program should flag the values to let the user know that they conflict with each other. -- 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: bz on 15 Jun 2005 13:29
H@..(Henri Wilson) wrote in news:1equa11h11huqcdprcjmqbii6peeg00tg5(a)4ax.com: >>> And this obviously explains how the 40 solar diameter delta Cep >>> and a star which hasn't got to be a neutron star at all, >>> can orbit their barycentre in the common period five days. >>>>Delta Cep: >>>>period = 5.366270 days >>>>radius = 41.6 solar radii >>>>mass = 5 solar masses >> >>two stars of 5 solar masses would orbit at 1.9e7 km >>41.6 solar radii is 2.8e7 km, which, as you have noted, is larger in >>than the orbital radius. So the stars would merge. >> >>In fact, in order for one to skim the surface (assuming zero radius for >>it), it would have to have a mass of 5.72 times the mass of delta Cep: >> >>This gives an orbital velocity of 268 km/s or 1.3e-3c >> >>I figure you need a very heavy black hole of at least 50 times the mass >>of Delta Cep. That gives a separation of 1.96 radii, orbital velocity of >>771 km/s or 2.5e-3 c >> >>All of these present a small problem, however, as the actual doppler >>data figures for RT Aurigae show a maximum velocity of 38 km/sec. At 38 >>km/sec, there is no way for the two stars to maintain orbit and they >>will fall into each other. > > That velocity figure is confusing. The RT Aur system is moving away from > Earth at 21 kms/sec..so you must subtract that. > > The maximum radial speed is only 17km/s. That just makes the orbiting stars model more impossible. But the max radial speed away from us (minimum) gets larger, so we should see more subluminal photons than super luminal photons. > >> >>That will make a big splash and, I fear, swamp Henri's model. > > There is known to be a lot of dark matter in the universe. > Apparently, much of it has cepheids orbiting around. Henri, there is NO possible mass that the cepheid could orbit in 5.36 days and have a radial velocity of only 21 kms/sec. The larger the mass, the greater the orbit's diameter AND the greater the orbital velocity. When M2 is 3e9 times M1, the orbital velocity reaches c. With an orbital diameter of 1.5e10 km. Obviously I have neglected to take into account relativistic increase in mass of the star with velocity. While working through some of these formula it became apparent to me that your program lacks a very important feature: A 'sanity check'. The program needs to flag inconsistent values. The orbital velocity, the orbits diameter, the mass(es) of the bodies involved, the eccentricity can NOT all be independently varied. Your program appears to assume that they can. I am sure there are other sets of interdependent parameters that likewise need to be cross checked. This means that one can put in values for interdependent parameters that are inconsistent with each other. I am not saying that you necessarily want to prevent specifying inconsistent values, but when they are input, they need to be flagged in some way. -- 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 |