It's a little hard to say that we understand the basics of gravity when we don't know the first thing about how it actually, you know, works.

Lawyers... :eyeroll:

Gravity... it's not just a good idea -- IT'S THE LAW.

There, that should do it for a while.

David:

The great physicist Richard Feynman told a story about how, when he was a boy, he had asked his father why a ball would roll forward in a wagon when the wagon stopped moving, and got an astonishing answer:

"Nobody knows."

His father went on to explain that we call that behavior momentum, and that it's a function of the ball continuing to move, but that no one really understands why it happens. Feynman (Jr.) said that he was profoundly influenced by this distinction between having a name for something and understanding it.

Writing that everybody thought gravity was understood is like hanging a sign around your neck saying, "I haven't heard any news for the last 100 years."

Pick up any physics text and you will discover that one of the great challenges today is a theory of quantum gravity.

I suspect that the Pioneer anomaly will turn out to be a measurement artifact. A few years ago, somebody decided to question the precision of Eotvos's measurements -- upon which most of what we know about gravity are largely dependent.

Turned out Eotvos was right on, as close as we know.

It's true that people like Orrin will never understand anything about gravity

Orrin, you seem to be under the impression that scientists claim to be omniscient and infallible, and so every time you see an article about a scientific controversy or unexplained phenomenon, you think that modern science is about to collapse. Some friendly advice: don't hold your breath.

What we're seeing is what pretty much always happens to theories when measurements are extended far beyond the scales on which they were originally derived. In 100 years we'll look back on dark energy, and perhaps dark matter in some respects, in the same way we look at things like epicycles--an attempt to make the prevailing model work, despite the obvious strains. This doesn't mean the current models will be thrown out completely, of course. Future physicists will merely speak of Newton, Einstein, and someone who's probably a grad student (or younger) right now.

Papaya:

Collapse? It's not standing.

Brian: exactly.

OJ: you sound like one of those leftists who's always talking about the imminent collapse of capitalism, a collapse which has supposedly been imminent since the days of Marx. 'Tain't happenin', bro.

Papaya:

Capitalism isn't rational, Communism was--it collapsed.

Well, either the measurement is wrong, or we will learn something more about near-interstellar space or gravity.

What's te problem with that?

OJ: Read Psalm 19 then calm down.

General Relativity is a well tested theory. Lots of experiments and astronomical observations have confirmed it. Examples include gravitational lensing, the precession of the perihelion of Mercury and the functioning of the GPS system.

Does the existence of some anomalous data invalidate General Relativity. No. No more than General Relativity invalidated Newtonian mechanics, which is still part of the kit bag of working physicists and engineers. Anomalous data my require a theory to be expanded, amended or even for a new theory to be invented. But General Relativity still explains an awful lot of stuff. Even though physicists have known for a very long time that General relativity is not a complete theory of Everything.

However, ever since the formulation of quantum mechanics in the 1920's physicists, including Einstein, have known that the two theories are both correct as far as they go, but are not consistent. The efforts of everyone (including Einstein and three subsequent generations of theoretical physicists) to formulate a theory of everything that would produce the same answers as quantum mechanics and general relativity within their respective realms and correctly answer extra questions have been so far unavailing. But even if such a theory is formulated, it is safe to say that General relativity will be safe within its domain.

I think there's much less here than it seems. The precise distance depends on a number of environmental factors of which we know even less about than gravity. It could be as simple as the instruments very slightly underreporting the local solar wind density.

To expand on AOGs comment.

The size of the error with respect to the overall distance is very, very small.

On the order of 1.3 light seconds over (I don't know the current answer) roughly 5 light hours.

That is roughly one part in 12,000.

There are darn few measurements in controlled, well understood, environments that can be made that closely.

You're all missing the point, predictably: it's not a question of jiggering the numbers until you can get the equation to work again.

You ever wonder if that guy who used to be on the Conan O'Brien show -- a well-dressed, clean-shaven portly fellow in his thirties ... pipe smoker ... in an easy chair, pleasantly making conversation yet inexplicably driving viewers into a frothing paroxysm of rage just from hearing him speak -- might have been drawn from life, and that the model was Mr. Orrin Judd?

Nobody's jiggering numbers, Orrin.

There are lots of reasons why the spacecraft might be going slower than expected, including -- perhaps -- that the interstellar medium, or some local part of it, is denser than we think.

Now, if it were going faster, that'd be another matter.

Anyhow, we can take it for certain that no matter how the theories of gravity have to be tweaked, we are not going back to watching projectiles make 90 degree course changes, which is what your team believed.

As for Darwinism on the junk heap, every one of those pathetic oldsters waiting in line for a flu shot was saying, loud and clear, 'I believe in the power of natural selection, no matter what I say.'

If it's broke, don't fix it.

That was the response of Christianity.

If Christianity is correct, smart bombs don't work.

Take your pick. You cannot have both

Technology works--science doesn't.

By the way, the walls of Jericho didn't float, they fell.

Science works. That is upsets some theological applecarts strongly suggests that it is theism that is at sea.

But that is only if you care to know how things are, rather than dictate to God how they must be.

Despite the theory of gravity breaking down my coffee cup doesn't then float away. Creation doesn't require that we comprehend it.

There you go againt, making conclusions from ignorance.

It didn't break down--1 part in 12,000, even if true, scarcely amounts to collapse.

So what if Creation doesn't require--or care if--we understand it? That doesn't mean we should stop trying, or have a hissy fit when successful attempts at understanding undermine the fairy tales of shephards.

Jeff:

You're right. I misspoke. As David points out there was no edifice to crumble in the first place. All we've done is confirm our ignorance of gravity.

1 part in 12,000, even if true, scarcely amounts to collapse.

1 part in 12,000, even if true, scarcely amounts to collapse.

Besides, to measure to that degree of accuracy, we must have electromagnetism down pat.

Yes, it's the lack of any support for the 12,000 that means there's no collapse necessary because nothing standing.

There is far more support for our knowledge of gravity than anything in the Bible.

There is gravity--it's our understanding of it that's non-existent.

Watch your use of the word "our."

Your understanding may be nonexistent, but that doesn't make it universally so.

No, it's reason that makes it so.

If only you would apply such standards to Theism.

We do--it just isn't wrong much.