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Are phottons effected by gravity?

  1. Jun 9, 2003 #1
    Some days ago some body posted a question saying are photons effected by gravity but was unanswered straightly. Here is the answer: Yes they are. They will be completly be stopped if an escape velocity of a planet is greater than the speed of light.
    Last edited: Jun 9, 2003
  2. jcsd
  3. Jun 9, 2003 #2
    First off, its 'photon'. Secondly, light isn't so much "affected" by gravity as it just follows the path of least resistance through space just as any object would. So if gravity were strong enough to form a rather deep gravity well, then light would bend through the path like a marble encountering a dent in the floor it's rolled across. That's how gravitational lensing works. Starlight encounters the gravity well of a rather large mass (star) and follows the curvature of spacetime forming an image of a star blocked from view by the object. A black hole can form a large enough gravity well to pull light beyond the event horizon were it can't escape.
  4. Jun 9, 2003 #3

    I was reading like: If at all a photons tries to escape a blackhole in which the escape velocity is higher than the speed of light the photon will never be able to escape. Is that not true? ofcource a photon is bearly affected. Like i said i am telling an answer. What is 9.8 m/s compaered to 3.00*10^8?
  5. Jun 9, 2003 #4


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    A black hole, by definition, is a body whose escape velocity is, at some altitude, greater than the speed of light. The mathematical surface surrounding such a body is called an 'event horizon.' On or inside this surface, the escape velocity exceeds c.

    And the number 9.8 is not a velocity -- it's an acceleration -- m/s2. You cannot compare a velocity and an acceleration, because they mean different things.

    - Warren
  6. Jun 9, 2003 #5


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    see this site answer

    BTW.. "Secondly, light isn't so much "affected" by gravity" this is incorrect it is. see explanantion

    good topic!
    Dx :wink:
  7. Jun 10, 2003 #6
    Re: Re: Are phottons effected by gravity?

    Well I sort of ment not in the way that gravity affects objects with mass.
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