Light and gravity

[vijaywantstoknow]

If light is being influenced by gravity, then the position of the space objects what we see is not their exact position, assuming, both the space object and earth are not moving. What i want to convey is, the light would have got deflected by the gravity of other space objects and wouldn't have followed a straight line when it reaches our eyes?

 

[heyscottie]

That is true. But we can estimate true positions by noting large foreground objects that could bend light of more distant objects.<br /><br />This effect even has uses for the astronomer: gravitational lensing. We can lens on object behind a galaxy or supercluster so it appears brighter than it otherwise would. In some images, you can see multiple views of a background object as light followed different paths around a foreground object to get to us.

 

[search]

<font color="yellow">If light is being influenced by gravity, then the position of the space objects what we see is not their exact position, assuming, both the space object and earth are not moving. What i want to convey is, the light would have got deflected by the gravity of other space objects and wouldn't have followed a straight line when it reaches our eyes?</font><br /><br />And it does not follow a straight line. That was exactly the solar eclipse and light experiment to prove Einstein theory. Ligh bends in the presence of major objects leke the sun.

 

[BoJangles]

<p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">If the following two statements are true,How can gravitational lensing work?</font></p><ul><li><div class="MsoNormal" style="margin-top:0cm;margin-left:0cm;margin-right:0cm"><font face="Calibri" size="3">Speeding something up to the speed of light makes it an infinite mass and uses an infinite amount of energy this must make light mass less;</font></div></li><li><div class="MsoNormal" style="margin-top:0cm;margin-left:0cm;margin-right:0cm"><font face="Calibri" size="3">Gravity is an effect involving 2 masses</font></div></li></ul><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal">&nbsp;</p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">Which statement is not correct?.</font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">Or is the fix here to say that lights mass is infinitally small, but not zero?</font></p> <div class="Discussion_UserSignature"> <p align="center"><font color="#808080">-------------- </font></p><p align="center"><font size="1" color="#808080"><em>Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog.  With that out of the way, I have several stupid questions... </em></font></p><p align="center"><font size="1" color="#808080"><em>*** A few months blogging can save a few hours in research ***</em></font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If the following two statements are true,How can gravitational lensing work?Speeding something up to the speed of light makes it an infinite mass and uses an infinite amount of energy this must make light mass less;Gravity is an effect involving 2 masses&nbsp;Which statement is not correct?.Or is the fix here to say that lights mass is infinitally small, but not zero? <br /> Posted by Manwh0re</DIV></p><p>I'd say your description of gravity is wrong.&nbsp; At least according to General Relativity it is wrong.&nbsp; GR describes gravity in terms of geometry.&nbsp; An object with mass curves spacetime.&nbsp; Any object passing through that curvature follow a geodesic path which is a straight line in curved space.&nbsp; Photons, despite being massless, still follow these geodesic paths.</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[BoJangles]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'd say your description of gravity is wrong.&nbsp; At least according to General Relativity it is wrong.&nbsp; GR describes gravity in terms of geometry.&nbsp; An object with mass curves spacetime.&nbsp; Any object passing through that curvature follow a geodesic path which is a straight line in curved space.&nbsp; Photons, despite being massless, still follow these geodesic paths. <br />Posted by derekmcd</DIV><br /><br /><p style="margin:0cm0cm10pt" class="MsoNormal"><font face="Calibri" size="3">Hrm I can accept that for an answer. </font></p><p style="margin:0cm0cm10pt" class="MsoNormal"><font face="Calibri" size="3">But it raises another question, as with our own milky way we experience very little gravity from the actual galaxy (due to its distance) and more from our immediate surroundings. I.e wouldnt we feel more of a gravity affect from our closest neighbours than that the centre of or combined milky way. <span>&nbsp;</span>In fact on earth it seems we&nbsp;feel more gravity from our sun that we can from our neighbours, if this is the case does light bend around our sun noticeably?</font></p><p style="margin:0cm0cm10pt" class="MsoNormal"><font face="Calibri" size="3">I.e. there doesn&rsquo;t seem to be enough mass at the edge of a galaxy to make a noticeable effect on anything let alone light.</font></p><p style="margin:0cm0cm10pt" class="MsoNormal"><font face="Calibri" size="3">Be gentle&hellip; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /></font></p> <div class="Discussion_UserSignature"> <p align="center"><font color="#808080">-------------- </font></p><p align="center"><font size="1" color="#808080"><em>Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog.  With that out of the way, I have several stupid questions... </em></font></p><p align="center"><font size="1" color="#808080"><em>*** A few months blogging can save a few hours in research ***</em></font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Hrm I can accept that for an answer. But it raises another question, as with our own milky way we experience very little gravity from the actual galaxy (due to its distance) and more from our immediate surroundings. I.e wouldnt we feel more of a gravity affect from our closest neighbours than that the centre of or combined milky way. &nbsp;In fact on earth it seems we&nbsp;feel more gravity from our sun that we can from our neighbours, if this is the case does light bend around our sun noticeably?I.e. there doesn&rsquo;t seem to be enough mass at the edge of a galaxy to make a noticeable effect on anything let alone light.Be gentle&hellip; <br /> Posted by Manwh0re</DIV></p><p>I'm not quite clear on what your question is...&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[BoJangles]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm not quite clear on what your question is...&nbsp; <br />Posted by derekmcd</DIV><br /><br /><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">I think what I'm trying to say is, on earth, we see a greater gravity affect from our sun then we do from the combined Milky Way. Meaning the entire milky way really isn&rsquo;t causing that much of a warping of space time around the outside (the distances are too great), so gravity would be very low on&nbsp;the outside&nbsp;(nothing like it is here on earth). </font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">If gravity can warp space time enough to change the direction of a photon around a galaxy, should&rsquo;nt we see some bending of a photon path as it passes by the sun or the earth, after all the gravity we feel here on earth would be a lot more than the gravity on the outside of a galaxy (where this lensing affect seems to take place).</font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">In the example I&rsquo;ve drawn below there is a halo around the foreground galaxy, note that the foreground galaxy is completely masking the background galaxy, the only path for the photon to take is around the outside which is why we see the Einstein ring (I think its called).</font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">&nbsp;BG</font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font face="Calibri" size="3">( G )</font></p><p style="margin-top:0cm;margin-left:0cm;margin-right:0cm" class="MsoNormal"><font size="3"><font face="Calibri"><span>&nbsp; </span>E</font></font></p><p><font size="3"><font face="Calibri">Knowing all this (assuming I&rsquo;ve got things right) <span>if this is the case, does light bend around our sun (or earth) noticeably, even just the smallest amount? Is this detectable?</span></font></font></p><p><font size="3"><font face="Calibri"><span>I&nbsp;guess there inst enough distance to see a notice the affect.</span></font></font></p> <div class="Discussion_UserSignature"> <p align="center"><font color="#808080">-------------- </font></p><p align="center"><font size="1" color="#808080"><em>Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog.  With that out of the way, I have several stupid questions... </em></font></p><p align="center"><font size="1" color="#808080"><em>*** A few months blogging can save a few hours in research ***</em></font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Knowing all this (assuming I&rsquo;ve got things right) if this is the case, does light bend around our sun (or earth) noticeably, even just the smallest amount? Is this detectable?I&nbsp;guess there inst enough distance to see a notice the affect. <br /> Posted by Manwh0re</DIV></p><p>Certainly.&nbsp; Using the sun during an eclipse to detect gravitational lensing was the very first confirmations of General Relativity done by Eddington.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>