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Topic: A black hole cannot pull light backward
Replies: 21   Last Post: Nov 19, 2011 11:42 PM

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james thomas

Posts: 36
Registered: 11/7/11
Re: A black hole cannot pull light backward
Posted: Nov 18, 2011 3:13 PM
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On Nov 18, 6:54 am, Paul Cardinale <> wrote:
> On Nov 14, 1:57 pm, Tom Roberts <> wrote:

> > On 11/13/11 11/13/11 - 3:34 PM, james thomas wrote:
> > > [... uninformed nonsense]
> > Replying to the subject: In GR a black hole DOES "pull light backward".
> > One of the best definitions of the event horizon of a black hole is that it is a
> > closed trapped surface. That is, the horizon is closed (has no boundary), and
> > trapped -- every non-spacelike (timelike or null) trajectory that intersects the
> > surface goes into its interior. That means no object can escape, and even light
> > that is initially emitted outward from the horizon actually goes inward. AFAICT
> > that contradicts your claim "cannot pull light backward".

> > Tom Roberts
> If an outward facing light source were to free fall into a black hole,
> wouldn't it be that the light emitted after crossing the event horizon
> would be moving outward with respect to the emitter, and inward with
> respect to the center of black hole?
> And, with respect to the falling emitter, the sliver of light emitted
> at the event horizon would be co-moving outward with the event
> horizon, and with respect to the center of the BH, be stuck at the
> event horizon?
> What happens to that sliver of light as other material falls into the
> BH, pushing the event horizon outward?
> Paul Cardinale

If light is not subject to being slowed down a black hole does not
work. If light is straight outward from gravity center it could never
boomarang or curve back.

Mitchell Raemsch

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