Search All of the Math Forum:

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

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

 Messages: [ Previous | Next ]
 james thomas Posts: 36 Registered: 11/7/11
Re: A black hole cannot pull light backward
Posted: Nov 14, 2011 8:18 PM

On Nov 14, 5:11 pm, xxein <xx...@att.net> wrote:
> On Nov 14, 4:57 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

>
> > Tom Roberts
>
> xxein:  Tom said "and even light that is initially emitted outward
> from the horizon actually goes inward."
>
> In that case, light from the central mass must go inward also.  M (in
> light meters of mass)*c^2/r^2 is a gravitational effect.  How do you
> explain that light (or anything to produce light) would even reach the
> horizon?
>
> What I'm trying to tell you is that an escape velocity is present.
> Maybe you don't think that it works with light also.  (2*M*c^2/r)^.5.
> Sorry for you.
>
> But there is a problem with that also.  Where does the light go?
>
> Certainly there is an accumulation of light on the event horizon that
> cannot escape.  Well?  What if a univeral expansion would take this
> mass to a less gravitational space?
>
> First of all, the rarified energy would decrease.  That would decrease
> the masss's intake to have the energy to have gravitation.  So?
> Light can now start to escape.  We call them quasars.
>
> I don't know for sure but gravity sure has an effect on light, doesn't
> it?
>

You can't stop light's C motion outward. It is not like matter with an
escape velocity. Light does not accelerate (or need to) to leave all
strengths of gravity.

Also black holes would be spatial boundaries and those should be
rejected.

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