Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

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

 Search Thread: Advanced Search

 Messages: [ Previous | Next ]
 james thomas Posts: 36 Registered: 11/7/11
Re: A black hole cannot pull light backward
Posted: Nov 18, 2011 3:13 PM
 Plain Text Reply

On Nov 18, 6:54 am, Paul Cardinale <pcardin...@volcanomail.com> wrote:
> On Nov 14, 1:57 pm, Tom Roberts <tjrob...@sbcglobal.net> 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

Date Subject Author
11/13/11 james thomas
11/14/11 herbert glazier
11/14/11 james thomas
11/19/11 herbert glazier
11/19/11 james thomas
11/14/11 Yousuf Khan
11/14/11 CWatters
11/14/11 Tom Roberts
11/14/11 Porky Pig Jr
11/14/11 james thomas
11/15/11 Paul Hovnanian P.E.
11/14/11 james thomas
11/14/11 xxein
11/14/11 james thomas
11/14/11 xxein
11/14/11 james thomas
11/15/11 Paul Hovnanian P.E.
11/15/11 Kurt Bashwitz
11/18/11 Paul Cardinale
11/18/11 james thomas
11/19/11 herbert glazier
11/19/11 Tom Roberts

© The Math Forum at NCTM 1994-2018. All Rights Reserved.