# Gravity is Relative!!! ;)

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#### why06

##### Guest
Someone decided if a sun was as big as our solar system it to could suck in light like a black hole... What I'm trying to say is that light has no mass except when at rest. So since even an atom has some mass while that may be little it is infinitely larger than a particle without mass. If I'm right than even an atom can suck in light. Which means a somethings has to be wrong. <br /><br />If this is not true someone state a reason why <img src="/images/icons/wink.gif" /><font color="yellow"></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

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#### kmarinas86

##### Guest
<font color="yellow">If I'm right than even an atom can suck in light. Which means a somethings has to be wrong.</font><br /><br />Atoms suck light (usually electrons). There's nothing strange about it. Electrons fling photons. Doesn't make it wrong. But like any "sucking" the "sucking" has a range. It's not so much more sucking than it is absorbing. Sponges don't really "suck" they absorb - though they do make squishy "sucking" sounds.

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#### why06

##### Guest
So technically everything is a black hole then what I'm trying to say then is that everything would create antimatter all the time...So wouldn't everything eventually evaporate like a black hole...<font color="yellow"></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

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#### Saiph

##### Guest
light has no mass, ever (especially since it can't be at rest).<br /><br />an atom does have mass, and if you compare it to a photon, that is infinitly more mass....<br /><br />But I don't see how you come to the conlcusion that even atoms can suck light. Just because they have infinitely more mass than a photon, doesn't mean they have infinite mass, they have a finite mass.<br /><br />The problem is: you're dividing by 0...that's a bad idea <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>

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#### why06

##### Guest
You see if light has no mass anything can suck it in because it as no resistance. An electron does have some mass, but a photon has none which means as soon as a photon hit a substance it would dissappear....making everything invisible.<br /><font color="yellow"></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

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#### Saiph

##### Guest
actually, according to classical physics gravity is the attraction between two masses. F=G*M1*M2 / R^2.<br /><br />If M1 is the mass of an electron, and M2 is the mass of a photon (0) then the resulting gravitational force is: 0.<br /><br />Only according to GR can light be affected by gravity since it has a different picture of how gravity works. It has a more accurate and complete picture b.t.w., that gives newtons equation when gravity is weak.<br /><br />And in GR, the electron doesn't have enough mass to appreciably affect light either. Our Sun barely alter's the path of light. <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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#### why06

##### Guest
In all reality it doesn't matter...I can see that the effects of gravity are between a mass and another mass and since a photon has no mass it is not affected by these laws. What it is effected by is space-time. Since dents in space-time are effected by an objects ratio of density to mass an electron would not effect space-time enough to to effects lights path, but as to this we do not know because we cannot measure the arc of space time in relation to this. Can we? If not the dents could be relative and effected by density. Wait that doesn't make since? Unless?<font color="yellow"></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

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#### Saiph

##### Guest
density does play an indirect role in determining the curvature of spacetime. More mass in less volume gives a sharper curve. So denser objects, per unit mass, will produce a stronger space-time curve. <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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#### elzzie

##### Guest
The reason a photon is able to be manipulated by gravity is because it is done indirectly. Since a photon has 0 mass, gravity can have no direct effect on it. But, gravity from a super massive object, like a black hole, will have an adverse effect on space-time. That being said, the reason nothing can escape a black hole's event horizon is not because of the direct force of gravity but because of the extreme curvature of space and time. The space is nearly curved around a black hole so much that when the black hole emits photons they cannot escape, due to the fact that they travel around the space time curvature back to the black hole itself.

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#### derekmcd

##### Guest
"<i>The reason a photon is able to be manipulated by gravity is because it is done indirectly. Since a photon has 0 mass, gravity can have no direct effect on it.</i><br /><br />Photons still have momentum and can exert pressure... therefore, they are a physical entity that can be affected by gravity.<br /><br />"<i>the reason nothing can escape a black hole's event horizon is not because of the direct force of gravity but because of the extreme curvature of space and time.</i>"<br /><br />Direct force of gravity = Newtonian physics<br />Curvature of spacetime = General Relativity<br /><br />In most cases they are interchangeable. I think, concerning black holes, the only difference is Newton never conceptualized the idea of infinite escape velocity. <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>

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#### derekmcd

##### Guest
Oh yeah... welcome to SDC <img src="/images/icons/smile.gif" />. <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>

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#### 3488

##### Guest
I wonder if this is better off in Phenomena??<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

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#### elzzie

##### Guest
<b> "Oh yeah... welcome to SDC. " </b><br /><br />Thanks!<br /><br />I should have worded my reply differently when going in to detail about a black holes affect of photons. But you guys are smart, I'm sure you know what I'm talking about.

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#### lukman

##### Guest
So it was not about gravity sucking light, but curving path of light, which is space. I have been in the forum for quite sometimes, what SDC stands for? -)<br /> <div class="Discussion_UserSignature"> </div>

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#### derekmcd

##### Guest
<font color="orange">S</font>ace <font color="orange">D</font>t <font color="orange">C</font>m <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>

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#### elzzie

##### Guest
<blockquote><font class="small">In reply to:</font><hr /><p> So it was not about gravity sucking light, but curving path of light, which is space. <p><hr /></p></p></blockquote><br /><br />Exactly.

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#### lukman

##### Guest
Thanks bro, i knew S stands for Space, i have no idea what D for, and i thought C is for Community -) maybe Space Dwelling Community lol. <div class="Discussion_UserSignature"> </div>

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#### derekmcd

##### Guest
Seriously Demented Conversations. <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>

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#### 3488

##### Guest
Perhaps this crap should be moved to phenomena too.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

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#### derekmcd

##### Guest
Or, perhaps, let it die a natural death. Just because a thread doesn't have a PHD level conversation happening doesn't mean it should be moved. <br /><br />I understand that some threads may be lacking some substance, but give them time to develop. <br /><br />Discussing gravity and the curvature of spacetime certainly belongs here. <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>

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#### lukman

##### Guest
I agree, in fact most high level discussion don't attract too many responses -) Just have fun, exchanging ideas -)<br /> <div class="Discussion_UserSignature"> </div>

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#### elzzie

##### Guest
<blockquote><font class="small">In reply to:</font><hr /><p> Perhaps this crap should be moved to phenomena too. <p><hr /></p></p></blockquote><br /><br />Why do I see you say this in almost every thread I read in the Space and Astronomy section?? Honestly, do you have nothing better to do than to cry about these threads than actually give any intelligent input on the subject? Give me a break.<br /><br /><b> Gravity is Relative </b> has great relevance to space science.

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