Question on rotation

[k2xl]

Hi, <br />I'm new here. My name is Danny Miller. I have a question that has bugged me. I'm afraid to ask my brother and law (a doctor in theoritical partical physics).<br /><br />If the I'm a partical in an accelerator going close to the speed of light... Earth is turning, which revolving around the sun. Combine all those speeds with the speed that the galaxy is turning (I read somewhere that our galaxy is rotating).<br /><br />I'm curious to know how come that partical wouldn't look like it's going at the speed of light to an observer looking at our galaxy from outside our galaxy. <br /><br />It's sort of a silly question I'm sure; I probably didn't explain my question well. I've just always been curious.<br /><br /><br />My second question is an idea I had which my brother and law (the clever &%$#@! <img src="/images/icons/wink.gif" />) shot down. My idea was a way that we could tell how far an object is from earth. When I was little I noticed if I closed my left eye and kept my right eye open, an object was at a different location then when I closed my right eye and opened my left. I was thinking that based on that distance apart, you could tell how far away an object is. My brother and law told me something that Einstein proved that would make my idea not work. Something about gravity affecting light or something.<br /><br />Was wondering if someone could explain in a less technical way? <br /><br />Thanks!<br />-Danny

 

[harmonicaman]

The speed of light, "c", wouldn't appear to be exceeded by an outside observer because at relativistic speeds (at or near "c") the "Addition of Velocities" paradox is governed by this scintillating equation:<br /><br />w = (u + v)/(1 + uv/c²)<br /><br />Here's one of several pages which discusses the "Addition of Velocity" conundrum.<br /><br />And here's a nice page about parallax; which is useful for measuring the distances of nearby stars, up to about 500 LYs away; after which the angle becomes so acute that accurate measurement by this method becomes problematic.

 

[Saiph]

yeah, that second part is parralax and is one of the primary foundations of the distances to <i>all</i> objects.<br /><br />The reason is, that for nearby stars, it is by far the most accurate, and most "direct" method employed (it's a geometrically determined distance, it isn't based on empirical or observational relationships). We use it to "calibrate" all of our other less direct distance methods.<br /><br />Your brother-in-law was probably thinking of gravitational lensing, which will screw up the path light takes, and make parralax innaccurate. however, this effect is much smaller than the other problem: The change in position of an object is so small, that we can only detect it on the nearest stars. At these distances any gravitational lensing complications are...well, non-existant.<br /><br />For more information, look up the "astronomy distance ladder", and tell your brother in law he was trying to make things to complicated. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[kmarinas86]

<font color="yellow">Your brother-in-law was probably thinking of gravitational lensing, which will screw up the path light takes, and make parralax innaccurate.</font><br /><br />If the pioneer anomaly is real, then we will have to reconsider parallax.<br /><br />http://www.google.com/search?q=sqrt%28Gravitational+Constant+*+1.99+*+10%5E30+kg+%2F+8.74+%2F+10%5E-10+m%2Fs%5E2%29<br /><br />sqrt(GM/Pioneer anomaly) = 3.8979062 × 10^14 meters

 

[Saiph]

maybe, but it's quite possible that anomolous acceleration has nothing to do with the light path. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>