goku Posted October 27, 2005 Report Share Posted October 27, 2005 i just had an amazing thought :) there is no way to know if light can travel for a year. :) Quote Link to comment Share on other sites More sharing options...
Jay-qu Posted October 27, 2005 Report Share Posted October 27, 2005 so where do you propose the light from all the stars comes from? Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 i don't know.think about it, the only way to know if light could travel for a year would be to take a light a lightyear away, turn it on and see if it takes a year for us to see it. Quote Link to comment Share on other sites More sharing options...
rockytriton Posted October 27, 2005 Report Share Posted October 27, 2005 sheesh, scientists have measured the speed of light, we see that the light from stars reaches us. Quote Link to comment Share on other sites More sharing options...
Buffy Posted October 27, 2005 Report Share Posted October 27, 2005 Well obviously this isn't a question about the *speed* of light since we can measure that over short distances in the lab and we've got extremely consistent data on that. And we've got our "light bulb"--Pioneer X--now out to about 12 billion kilometers or half a light day, and while thats about 1/700th of the distance you're asking about, its far enough to start to show some "weakening" of the "light" (electromagnetic transmissions are equivalent), which we don't see. if it were going to wink out completely before it hit 1 light year, we'd see some weakening by now but we don't.  So the conclusion is, it sure looks like light travels at least a light year if not more, and absent some theory about how that light that's clearly much further away (note that anything only a light year away would show *huge* measurable parallax with existing telescopes, so we know this stuff is really far a way) gets to us while something a light year away would not be strong enough to get to us, its pretty much proven that yes, indeed, light can travel a distance longer than a light year.... QED,Buffy Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 So the conclusion is, it sure looks like light travels at least a light year if not more, and absent some theory about how that light that's clearly much further away (note that anything only a light year away would show *huge* measurable parallax with existing telescopes, so we know this stuff is really far a way) gets to us while something a light year away would not be strong enough to get to us, its pretty much proven that yes, indeed, light can travel a distance longer than a light year....this is based on the theory that stars are lightyears away, there's no possible way to know for sure.the atom bomb looked great on paper, but for some dumb reason they tested it anyway :) Quote Link to comment Share on other sites More sharing options...
C1ay Posted October 27, 2005 Report Share Posted October 27, 2005 i just had an amazing thought :) there is no way to know if light can travel for a year. :)The corollary to that is that all stars, galaxies, pulsars, etc. are less that one light year from Earth yet trigonometric parallax tells us otherwise. Are you implying that this method of mathematical derivation of star distance could be flawed? Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 The corollary to that is that all stars, galaxies, pulsars, etc. are less that one light year from Earth yet trigonometric parallax tells us otherwise. Are you implying that this method of mathematical derivation of star distance could be flawed?test it on a star and see.but then you must first know how far away the star is.maybe flawed, maybe not :) how can we know? Quote Link to comment Share on other sites More sharing options...
Tormod Posted October 27, 2005 Report Share Posted October 27, 2005 test it on a star and see.but then you must first know how far away the star is.maybe flawed, maybe not :) how can we know? Here is a good start to learn more about this problem: How are astronomers able to measure how far away a star is?http://science.howstuffworks.com/question224.htm Quote Link to comment Share on other sites More sharing options...
Tormod Posted October 27, 2005 Report Share Posted October 27, 2005 the atom bomb looked great on paper, but for some dumb reason they tested it anyway :)Â And it worked, too. Quote Link to comment Share on other sites More sharing options...
C1ay Posted October 27, 2005 Report Share Posted October 27, 2005 but then you must first know how far away the star is.how can we know?No, surveyors use parallax all of the time to measure distances to things they can't access and don't already know the distance to. Did you read my link or Tormod's? Quote Link to comment Share on other sites More sharing options...
rockytriton Posted October 27, 2005 Report Share Posted October 27, 2005 I have a serious question for you goku, do you believe that man actually landed on the moon? Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 went to the site, that might work as long as our sun and the star being measured are both stationary. Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 No, surveyors use parallax all of the time to measure distances to things they can't access and don't already know the distance to. Did you read my link or Tormod's?tormod's Quote Link to comment Share on other sites More sharing options...
C1ay Posted October 27, 2005 Report Share Posted October 27, 2005 tormod'shttp://science.howstuffworks.com/question224.htm Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 I have a serious question for you goku, do you believe that man actually landed on the moon?yep, but i have relatives that don't and they never thought to question star distance or light year. Quote Link to comment Share on other sites More sharing options...
goku Posted October 27, 2005 Author Report Share Posted October 27, 2005 brightness measurements:a car's headlights are blue, how far away is it?all these methods sound good, but there's no way to test them. Quote Link to comment Share on other sites More sharing options...
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