Re: Does Newtonian gravity bend light?

[Larry Smith <Larry.Smith@SNOW.EDU>]

At 4:55 PM -0500 12/14/00, Hugh Haskell wrote:
> > One of the textbooks on my desk says regarding predictions of GR "Gravity
> > should bend light rays, an effect not predicted by Newtonian mechanics
> > because light has no mass."  Yet
> > <http://www.theory.caltech.edu/people/patricia/lclens.html> claims that
> > Newtonian gravity bends light, just less than Einsteinian gravity does.
> > What gives?
> >
> > Thanks,
> > Larry
>
> Interesting. What text is that?

It is an intro astronomy book.  Later it says, "Light rays are deflected by
the curved spacetime around a massive object like the Sun.  The maximum
deflection is very small, only 1.75 arcsec for a light ray grazing the
Sun's surface.  By contrast, Newton's theory of gravity predicts that there
should be _no_ deflection at all."

Thanks, Hugh, Leigh, David, Roger, for your responses; they are helpful.
In summary, would you say the textbook quotes are OK, or should the
publisher/author modify them?  If modified, then how?  What is the best way
to present this to intro astronomy students as evidence for GR and against
Newtonian physics?

Thanks again,
Larry