🚀 go-pugleaf

On Jun 21, 7:07 am, Pentcho Valev <pva...@yahoo.com> wrote:
> http://www.nature.com/news/2010/100617/full/news.2010.303.html
> NATURE: "Gravity is mercilessly impartial - on Earth, it accelerates
> light and heavy objects alike with a tug of 9.8 metres per second
> squared. That property is the cornerstone of Albert Einstein's theory
> of general relativity, which states that gravity is indistinguishable
> from any other type of acceleration."

Argh! What a poor and sloppy way to put it...

> That gravity "accelerates light and heavy objects alike with a tug of
> 9.8 metres per second squared" is true but this is Newton's emission
> theory of light developed by John Michell in the 18th century and
> temporarily adopted by Einstein in 1911. If NATURE's editors were both
> honest and knowledgeable they would have published the following text:
>
> "Gravity is mercilessly impartial - on Earth, it accelerates light and
> heavy objects alike with a tug of 9.8 metres per second squared. That
> property is the cornerstone of Newton's emission theory of light; it
> is equivalent to the fact that, in the absence of a gravitational
> field, the speed of light varies with the speed of the emitter, v, in
> accordance with the equation c'=c+v."

They should have cited Einstein instead, according to whom light bends
but does not accelerate while approaching the Earth.

> Although in 1911 Einstein was on the right track, in 1915 he spoiled
> everything by making light accelerate faster than cannonballs by a
> factor of two:
>
> http://www.mathpages.com/rr/s6-01/6-01.htm
[..]

No. And here Kevin Brown explains the factor two much better:

http://www.mathpages.com/home/kmath115/kmath115.htm

Harald