PHANTASM Posted August 7, 2010 Share Posted August 7, 2010 @ phantasm -- OOPS i didn't read all the thread before i posted.. %800 off LMAO i was not aware of that result. but i have always been skeptical about hubble's law and redshift in general -- i am not at all surprised. as you said, gravitational effects on light cause redshift. interstellar dust causes redshift. for all we know, photons degrade over periods of millions of years, causing redshift. when you think about 70% or more of the matter/energy density of the universe possibly being unknown, you start to wonder just what else might be out there interfering with light and also causing redshift. not surprised at all... thanks for the info! Yeah the redshift measurement was off by a factor of 8, because the galaxy is being warped by a collison with the other galaxies, which throws a monkey wrench into a lot of astronomy textbooks. The redshift is not about the color of a star, it doesn't matter what stage in the life cycle the star is in. It uses the shift in the elemental spectrum due to the velocity the object is moving away from us at. It seems that blackholes and collisions really mess up this calculation, and we don't know how much matter is netween us and whatever we are looking at, so now we don't know if ANY of our deep space measurements are accurate. Good to have you guys in the discussion. Quote Link to comment Share on other sites More sharing options...
MadHatter Posted August 7, 2010 Share Posted August 7, 2010 another trick is to use a 'standard candle' -- there is a type of star called a cephid variable that gives off pulses of light at a regular rate. they're like lighthouses, rotating and shining a beacon at you every time they face you. well the faster they spin, the faster the pulsing.. neat thing is ( thanks, God ) that their luminosity -- absolute magnitude & radiation you can't see; magnitude is only visible light -- can be very precisely calculated if you know how fast they pulsate. basically, if you find a cephid variable in a certain galaxy, you can watch how fast it pulsates and figure out it's absolute magnitude - from it's apparent magnitude you can then figure out about how far away it is. this gives you a rough estimate for the distance to all the stars in that galaxy! The maths of this is explained in my earlier post Quote Link to comment Share on other sites More sharing options...
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