Don't be prematur. Just because unexpected drag has occured doesn't mean the theory of gravity is wrong, it just may need a lil tweaking as all theories enevitably do. It could be from somthing much more prosaic, allthough since I'm dead tired right now can't really think of any right now, will post if I think of any b4 bed. Don't jump to conclusions.

odds are the ships are hitting a layer of gas not thick by any means but enough to cause drag.

We also know verry little about the area directly outsied of the solarsystem such as teh Ort cousd and Kuiper belt. We also do not know the extent of Sol's gravitonal pull out there and effects. Another thig is they reported solar energy that far out which was thoguht to be impossible. This is alot in space we don't understand. Just to find one thing that fits and throw it in is not exactly a great Idea it could be thousands of thing. We just dont have alot of knowldge in the area,

And since void causes matter to clamp together, the Pioneer spacecraft slows down the it goes into the interstellar space.

This also explains the accelerating expansion of the universe.

Also note - they have not done the full orbital element calcs for the outer planets. The probes have to be run through a series of calcs with the gravitation effects of all the bodies in the solar system. It's a harry calc and it's iterative and has to be stopped at some point by humans. I think they've only done out to Saturn so far as the JPL kids have to do this when they launch stuff and even then, they have to do course corrections as it's never quite right.

Also consider all the small bodies (asteroids, comets, etc.) out there - they also have gravitational effects so it may be error in calcs as well as other possible effects - dust or other crud causing drag - space is not actually empty, just close to it and we may be off in our measurement of all of that stuff - density of H may be thicker out there and while it may not effect the planets, it could effect a small probe.... We also have to rely on orbit data to calculate mass and if that is off just a bit that could cause the error as well....

Jury is still out on this one....

Particles, beginnings of the Oort cloud? They have already been researching this phenomena...

Indeed, the 'void' is not void at all. Not only is it filled with neutrinos, but it is also filled with an immense amount of particles popping in and out of the universe at each point in time.

But the neutrinos you mention are very few per cubic meter, and it is still not proven conclusively that neutrinos have mass.

The void must be made out of something that we perceive it as void, but to an outside observer it would be obvious what is the cause of gravity. Unfortunately, we are on the inside, so we can't really tell what's going on.

Seams everone is missing the most important thing with this.If the probe has slowed down so much that its now 250,000 miles from where it should be will it still be able to excape the solersystems gravity or just go into a longg orbit. If it doesent excape the solersystems gravity then mans attempt at sending a probe out of our system has FALED . The earths one true time capsel that would have lasted BILLIONS of years easted in a never ending orbit around the outer edge of the solersystem .What a waste .
Please someone tell me that NASA has said it will still excape the soler system.

To be sure, the anomaly was small, just 8 X 10--8 centimeters/second2. That amounted to about 8,000 miles a year, a tiny fraction of the 219 million miles the spacecraft covered annually. The anomaly is about 10 billion times weaker than the Earth's gravity.

Yes, Simcity, the probes still have enough velocity to escape the solar system. 248,000 miles is nothing compared to the distance already travelled.

Neutrinos don't just sit there - they are zipping along at c or close to it - ouch one just went thru me - damn, I hate when that happens....

Yes - probes have more than enough speed to escape solar system - gravity is a distance/mass thing and probes are small mass and moving fast and far out from Sun so little effect. If they stopped - yes, they would take up a Sun centered orbit but they are a bookin....

Isnt the probe near or aroung the termination shock zone where there is very little gravity and a lot of radiation solar and plasma storms could that be slowing it down.

Knowing nothing about physics, i would guess that the atoms hitting the spacecraft are accelerating faster than usual due to lack of friction and hitting it, cumulatively slowing it down.

Just a guess.

That said, scientists are always finding stuff that contradicts current theories. Its amazing how many people take what they say for granted as fact.