[Lex Computer & Tech Group/LCTG] Speed of gravity

[Ted Kochanski]

>
> "hey measured the speed of gravitational waves compared to the speed of
> light, by recording the relative time that the two waves reached Earth from
> an event that occurred 130 million years ago when two neutron stars
> collided and thus emitted both gravitational waves and light waves.

The gravitational waves and light waves arrived within 2 seconds of each
> other...

The article concludes that the two speeds (gravity, light) are exactly the
> same
> However, how do they account for the 2 seconds difference in the arrival
> time of the two waves?"

.

The problem as stated is is ill-defined as we do not know to within 2
light-seconds the locations of the sources of the two "emissions"
My guess would be that the collision between the two neutron stars produced
an emission of something unobserved such as neutrinos which in-turn
interacted with some near-by cloud of ordinary [or non-ordinary matter] not
involved in the collision directly and the "shock front" then led to light
output by something like Cherenkov radiation or Askaryan radiation [whereby
a particle traveling faster than the phase velocity of light in a
dielectric medium produces a shower of secondary charged particles which
contains a charge anisotropy <https://en.wikipedia.org/wiki/Anisotropy> and
thus emits a cone of coherent
<https://en.wikipedia.org/wiki/Coherence_(physics)> radiation] as in
the  Cherenkov
radiation [for charged particles]
We see such shock-like luminance in supernovas, "gamma-ray bursters"
"blazars"  and other exotic energetic astrophysical phenomena

the location of the cloud where the CR or AR emission occurred could easily
be 2 light-seconds from the actual collision of the neutron stars

Ted

On Thu, Oct 27, 2022 at 2:42 PM Steve Isenberg <smisenberg at gmail.com> wrote:

> According to the speed of gravity article, they measured the speed of
> gravitational waves compared to the speed of light, by recording the
> relative time that the two waves reached Earth from an event that occurred
> 130 million years ago when two neutron stars collided and thus emitted both
> gravitational waves and light waves.
> The gravitational waves and light waves arrived within 2 seconds of each
> other.
>
> The article concludes that the two speeds (gravity, light) are exactly the
> same (which on one hand makes sense).
>
> However, how do they account for the 2 seconds difference in the arrival
> time of the two waves?
>
> I suspect that it's due to gravitational influence of objects between us
> and the two neutron stars, or maybe the distance between locations of the
> two instruments on or near Earth (but I would have expected them to account
> for this).  Or maybe the light was emitted by the neutron star collision
> just a little before or after the gravitational waves.
>
> Anyone here have any thoughts on this?
> -steve
>
> On Thu, Oct 27, 2022 at 2:23 PM john rudy <jjrudy1 at comcast.net> wrote:
>
>> Pretty interesting
>>
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