False Claims of Gravity Propagation Limit

[Växan]

Ed Fomalont of the National Radio Astronomy Observatory and Sergei Kopeikin from the University of Missouri in Columbia, performed an experiment on 18 September 2002 using an array of radio telescopes around the world

they observed light from a faraway galaxy bend as the planet Jupiter passed almost directly between the galaxy and the Earth

and their theory stated that the bending would occur due to the gravitational influence of Jupiter

this is absolute rubbish, the premise of the experiment is fatally flawed
and the result being equal to lightspeed is due to fact that they in fact meaured the speed of light, and not the propagation of gravity

in fact any measurement based on electromagnetic observation will be limited to lightspeed no matter what!

in the Newtonian model, gravity propagates instantaneously: the force exerted by a massive object points directly toward that object's present position

for example, although the Sun is 500 light seconds from the Earth, Newtonian gravity describes a force on Earth directed towards the Sun's position "now," not its position 500 seconds ago. Putting a light velocity travel retardation into Newtonian gravity would make orbits unstable,
leading to predictions that clearly contradict planetary observations

the fact is, gravity propagation is unmeasurable using current technology
and by all accounts gravity acts at off the scale velocities
and therefore is virtually instantaneous - the true nature of gravity is still unknown to physics, GR makes predictions of course, however these predictions are untestable and unmeasurable

it is not known whether gravity is a force, or a consequence

Ed Fomalont and Sergei Kopeikin deserve the title "king for a day"
(the fool 'Punch' from pagan May Day festivals) and should be congratulated for confirming the velocity of light to within 20% of the already known figure

well done!

i have never seen such a naive experiment

the results of which of course make sensational news - how hard is it to awe the common masses who know absolutely nothing about gravity or physics in general

physicist Peter van Nieuwenhuizen called the interpretation of the results by Fomalont and Kopeikin "compete nonsense"

Japanese physicist Hideki Asada published a paper, also in the Astrophysical Journal Letters, arguing that Fomalont and Kopeikin would actually be measuring the speed of light, not gravity

in fact physicists around the world have completely discredited the results,
the methods, and Fomalont and Kopeikin themselves

it reminds me of the Cold Fusion scam of Pons and Fleischman back in the 80s

 

[Hurkyl]

Is Tom Van Flandern's stuff still floating around?

in fact any measurement based on electromagnetic observation will be limited to lightspeed no matter what!

This is ridiculous. The speed of gravity (or any other force that could affect a beam of light) can be measured by observing how long it takes for a change in the gravitational source to result in a change in how the beam of light is bent.

in the Newtonian model, gravity propagates instantaneously: the force exerted by a massive object points directly toward that object's present position

for example, although the Sun is 500 light seconds from the Earth, Newtonian gravity describes a force on Earth directed towards the Sun's position "now," not its position 500 seconds ago. Putting a light velocity travel retardation into Newtonian gravity would make orbits unstable,

Well, the first problem with this is that orbits are unstable; one of the famous confirmations of General Relativity, one that is entirely inexplicable by the Newtonian model, is how the orbits of binary pulsars decay. Planets, on the other hand, simply don't bleed off enough gravitational radiation to have any noticable effect.

The second problem is that light velocity travel retardation does not prevent a force from pointing towards where the object is "now"... electromagnetic fields are a classic example; they have a built in linear correction so that, despite "light velocity travel retardation", the electromagnetic force always points were the electron is "now" rather than "then", assuming the electron moves along a straight line. Gravity, via GR, has both a linear and a quadratic "correction".

The third problem is that you assume because a propagation of speed of gravity contradicts observation according to Newtonian gravity, it will also cause the same contradiction in other models.

the fact is, gravity propagation is unmeasurable using current technology
and by all accounts gravity acts at off the scale velocities

Could you point to an experiment which suggests the speed of gravity is too fast to measure?

The only references I have ever heard to this are theoretical proofs that planets would fly away if Newtonian gravity were augmented with a propagation delay; IOW it has nothing to do with an experiment and nothing to do with current gravitational theories.

 

[chroot]

Naive attacks on well-established science are, in my opinion, crackpot nonsense. According to the guidelines of physicsforuns.com, such attacks can only be posted in the Theory Development forum. I am thus moving this thread to TD.

- Warren

 

[Michael F. Dmitriyev]

I am interested with one question in this problem. Coordinates of the far star as source of a light beam are taken as existing at the moment of experiment. Is it not a fatal mistake?