Photons

[mubashirmansoor]

As I was reading about photons, Some of the information was puzzeling for like; photons have no mass or that they dont have a kinetic energy.<br /><br />I understood having a zero mass at rest but when traveing with the speed of light the photons should gain a mass ( I think ) because of 2 universal evidences 1) The space-time curvature of a body such as a star causes the gravitational lensing and should the light have a mass to be affected by the mass of the sun? 2) The light is completely trapped in a black hole because of its extreamly intense gravity or the space-time wrapture so should it have a mass to be effected by the gravity?<br /><br />The next was about the Kinetic energy of light but if I understand the problem with the mass I will sure solve this one myself <img src="/images/icons/smile.gif" /> <br /><br />I'll be really thankfull for your answers. <br /><br />To make much more clear what I mean is that; If and if photons gain a mass due to their speed they probably have a kinetic energy too. right? <br />If so than E= (2ke/c^2)c^2 which means E=2ke which again means:<br />E=2(mv^2/2) where v=c so E= mc^2 And this shows that the mass is because of the speed and that the mass is variable at least in case of Electromegnatic rays...??<br />

 

[harmonicaman]

<i>"...should it have a mass to be effected by the gravity?"</i><br /><br />Gravity is merely the curvature of space and time. The photon cannot escape the BH, but this has nothing to do with its relative "m" (mass), it is because the space around the BH is infinitely curved -- from the photon's perspective it: <br /><br />1. Is always traveling in a straight line.<br />2. Does not experience the passage of time -- it is both created and annihilated at the same instance.<br /><br />All "m" becomes infinite at "c" (the speed of light) velocities.

 

[mubashirmansoor]

Light has its own time frame & that it will expirience the passage of time but zero relative to us. right? & About the gravity do u mean that its actually the energy which makes the space time curve around a body & not the mass. But doesn't sounds correct and I must have misunderstood sth. I'll be thankfull for further information.

 

[Saiph]

Harm's got it right. Light is affected by gravity, but not in the same way an object with mass is. It has to do with space-time being curved, and altering the apparent paths of straight lines.<br /><br />Also, you're proof for E=mc^2 is in error. Energy /= 2*kinetic energy...that's a bad thing! <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>