Measuring bent light

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wurf

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Since galaxies can orbit each other, then separate bodies of mass relatively close to each other must form a collective center of gravity, or else one galaxy is orbiting a single mass in the other galaxy. If our sun is massive enough to bend light around it, then don't galaxies bend light around them? If so, is this accounted for when we measure the distance and location of distant galaxies? Would the bending of the light give us inaccurate readings of the amount of redshift, or would the effects be negligible? And when we view any distant point(s) of light, how can we know we're not looking at light which has been bent at a 45 or 90 degree angle from its source, due to its traveling near an intergalactic black hole?

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bobw

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It happens. It is called gravitational lensing. The far away objects are often distorted into arcs like the picture at the link below. Another thing to look up would be Einstein Cross.<br /><br />http://apod.nasa.gov/apod/ap011007.html <div class="Discussion_UserSignature"> </div>

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qzzq

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Actually, photons are unaffected by gravity, because they have no mass. Gravity bends space time though, and thus the path the photon is travelling. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

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wurf

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When light moves into water from air, it's bent or angled due to its speed change. Does light bending due to gravity also change speed?

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alokmohan

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Very good ,full marks.

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qzzq

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<i>Does light bending due to gravity also change speed?</i><br /><br />No, only the path of the photon is altered, not its velocity. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

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wurf

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Is there a certain amount of mass it takes to bend light, or does all mass bend light? If you drop a pea to the ground, the pea is attracted to the center of the earth, but the earth is also attracted toward the pea, so I assume even a pea bends lights to some miniscule degree?

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MeteorWayne

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That would be correct, but the amount of bending from the pea would be immeasurably small. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

A

Guest
Yeah, but given enough peas... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>

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MeteorWayne

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As Mr Lennon said, "Give peas a chance...." <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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primordial

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qzzq ! Yes and no, you are correct . The photon has zero rest mass and relativistic mass that is inversely proportional to its wave length or directly proportional to its frequency, and its gravity will also change space-time.

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Saiph

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qzzq:<br /><br />:::cough::: velocity has a directional component :::cough:::<br /><br />So the speed is unaltered, but the direction of travel (and thus it's velocity) is. <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>

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primordial

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qzzq ! It (light) propagates along geodesic lines through space-time, considered the path of least resistance, I wonder if it (light) should travel through a worm hole, how should the speed or velocity be determined. If the light source was from a region on the other side of our universe that would have an identical red shift as we, yet be 27 billion light-years away, how would we ever know the location of the source, how could we ever know it was a worm hole, if the light or mass or what ever came through it was identical to all other mass or light in our own region. It would just appear. Could it be space-time is full of small worm holes allowing quantum size particles to pop in and out as they appear to do any way?

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jgreimer

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Einstein said that the "G" force experienced by acceleration is indistinguishable from gravity. So if a light beam passing through an accelerating spaceship traces a curved path to observers on the spaceship, it must also trace a curved path through a gravitational field.<br /><br />Yes, galaxies do bend the light of other galaxies behind them but this is a fairly rare phenomenon. If astronomers wanted to measure the red shift of the galaxy whose light is being bent, one would think that the additional red shift the light acquires from the gravity of the intervening galaxy would by exactly countered by the blue shift the light experienced as it approached the galaxy. Thus the bending of the light shouldn't have any effect on the redshift.

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primordial

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jgreimer ! Yes you'r right it is blue shifted, but then the standard we use to compare it against is also blue shifted, because it's here with us.

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