Pioneer Anomoly almost explained...

[archeryguy1701]

http://online.wsj.com/article/SB121087447348895873.html?mod=yhoofront

The Pioneer anomoly was first observed in 1988 when scientists noticed that Pioneer 10 and Pioneer 11, probes going off in opposite directions, were drifting thousands of miles off course. Quite simply, if there wasn't an explanation for this, it would fly in the face of Newton's and Einstein's theories on Gravity. Well, after years of work, scientists have discovered a part of that drift:

After six years of work, the researchers expect to finish restoring the last data files next month. Based on a partial analysis, Dr. Turyshev reported in April at a meeting of the American Physical Society in St. Louis that at least 30% of the force can be attributed to heat radiating from the probe.

However...

"The rest is unknown," he said.

So, what else do you think is contributing to the Pioneer Anomoly? Do you think there is a practical and logical reason, or do you think that there may be something fundamentally wrong with the laws of gravity?

 

[Lookingglassman]

Solar winds? Or maybe they ran into something like a rock that nudged them off course?

 

[Shaw]

Quite simply, if there wasn't an explanation for this, it would fly in the face of Newton's and Einstein's theories on Gravity.

-and-​

So, what else do you think is contributing to the Pioneer Anomoly? Do you think there is a practical and logical reason, or do you think that there may be something fundamentally wrong with the laws of gravity?

So one has to wonder... what is it that you are expecting from this type of article?

Before addressing the article itself, lets first note that news writers have known for more than 80 years that the addition of the name Einstein to the headline will increase the number of readers. And we aren't just talking about your supermarket tabloids, the mainstream press has been using this for years too.

Secondly, don't expect good science from the press. This is like expecting sound life advice from fortune cookies. A classic example...

"Einstein Completes Unified Field Theory", New York Times, January 1931​

So beyond the fact that this article has to be approached with a massive amount of skepticism... what do the facts point to? Well, what did the article say?

"The anomaly officially materialized in 1988, 16 years after NASA launched Pioneer 10 toward the outer planets."​

Really? Well, if it wasn't effecting the entire voyage of the spacecrafts, I think we can safely rule out issues with our understanding of gravitation.

What one has to remember (and is often forgotten by SciFi fans) is that we know precious little about interstellar space. Just like the Earth protects us with it's atmosphere, the Sun protects our solar system with it's atmosphere. And the Pioneer spacecrafts were the first to start reaching the boundaries of our Sun's influence. We know that the Sun is moving through space, but we have almost no idea what the interstellar medium might be like. Or how it might be moving relative to our solar system.

So while there are countless numbers of unknown phenomena that could be causing this, I doubt that any of Einstein's work will have played any part in it.



... but this article does continue to show that the use of the name Einstein in a headline has not diminished in it's ability to pull in readers.

 

[Lindley]

It's just falling towards a wormhole which leads to a machine planet, that's all. Nothing to worry about.

 

[archeryguy1701]

^^Fortunately, Einstein wasn't even mentioned until I clicked the link. The Yahoo main page had an alternate title, a very brief synopsis, and then the link. Thus, Mr Einstein had nothing to do with my interest.

And, my understanding of this statement and the paragraphs after it:

The anomaly officially materialized in 1988, 16 years after NASA launched Pioneer 10 toward the outer planets.

...Was that they didn't notice it because the amount it was drifting by was so small that it was barely noticeable. Heck, the guy who found it even said that the change would have normally gone overlooked if the number discrepencies didn't bother him. Besides, the probe sent off in the opposite direction is drifting by the same amount.

 

[Shaw]

^^Fortunately, Einstein wasn't even mentioned until I clicked the link. The Yahoo main page had an alternate title, a very brief synopsis, and then the link. Thus, Mr Einstein had nothing to do with my interest.

Well, that doesn't change the fact that his name was part of a headline of a story which really had next to nothing to do with him. I doubt that was a mistake.

But as I said, there really isn't enough data in the article (nor is the writer informed enough) to make any judgments on what was presented. And no one really interested in this topic should be viewing this article as anything more than fluff.

On the other hand, there is the 42 page paper on the subject... what was your impression of that?

What was odd from my first skimming of the paper is that the acceleration is noted as a doppler shift in the radio signal... yet I'm not seeing any references to time dilation that would be caused by the spacecraft's change in position (as it moves further away from the Sun). The flow of time changes in the presence of a gravitational field, which could have such an effect.

Unfortunately the paper makes references to a number of other people's theories, but doesn't take the time to fully outline all of them in any great detail (which, of course, would have most likely made that paper more of a book).

My understanding of how JPL has dealt with most of their missions is that standard Newtonian gravitational equations are employed for their navigation, and that aspects of General Relativity wouldn't come into play unless the path of the spacecraft passes closer to the Sun than the orbit of Venus.

Also additional aspects of the solar system are given the values of zero when they actually aren't. The particles in the solar winds may seem like something that can be overlooked, but their presence in our solar system gives the whole system a gravitational footprint of a massive fuzzy sphere rather than a number of discrete bodies in regular orbits.

Some of this stuff should be easy to check out (the geometry for the time dilation hypothesis was put forward by Schwarzschild years ago) while others might require some complex modeling.

I sure hope that it isn't time dilation though... I mean that is such a obvious factor that one would hope that it had already been taken into account. Specially if someone in a Star Trek forum who doesn't even specialize in physics would think of it. When I get a chance to look at the data (and the analysis) closer maybe I'll calculate what type of doppler shift would be expected over the life of the spacecrafts. Sounds like an interesting exercise (if nothing else).

 

[FordSVT]

I'm definitely not worried that our understanding of physics is incorrect, just incomplete. We're able to accurately predict the motion of extra-planetary bodies and our other spacecraft quite reliably and moving over much larger distances and periods of time than Pioneer, if our theories were that screwed up we would have noticed a long time ago.
There's an unknown factor at play here, either something with the probe itself or something in the solar system is influencing it somehow.

 

[Ronald Held]

I am waiting for the research grade article on the current analysis.

 

[Verteron]

I'm definitely not worried that our understanding of physics is incorrect, just incomplete. We're able to accurately predict the motion of extra-planetary bodies and our other spacecraft quite reliably and moving over much larger distances and periods of time than Pioneer, if our theories were that screwed up we would have noticed a long time ago.
There's an unknown factor at play here, either something with the probe itself or something in the solar system is influencing it somehow.

Not necessarily. The motion 7 of the 8 of the planets, for example (all except Mercury) can be calculated perfectly well using Newton's laws alone, without even factoring in General Relativity. Our current laws, if anything, are likely to be good approximations of the physical situation, which naturally break down in extreme cases, like at Event Horizons or potentially in the case of the Pioneer probe anomaly.

 

[Verteron]

Before addressing the article itself, lets first note that news writers have known for more than 80 years that the addition of the name Einstein to the headline will increase the number of readers. And we aren't just talking about your supermarket tabloids, the mainstream press has been using this for years too.

I'm not sure what your point is here, it's lost on me. When considering gravitation, Newton and Einstein are by far the most relevant names associated with the subject, having themselves published the two most widely used formulations of the gravitation field in the last 400 years, namely, F = GMm/r^2 and the Einstein Field Equations, published in 1915. So it's entirely proper to bring their names in to an article headline when considering evidence that these two masterful successive explanations may not be quite up to the task.

So beyond the fact that this article has to be approached with a massive amount of skepticism... what do the facts point to? Well, what did the article say?

"The anomaly officially materialized in 1988, 16 years after NASA launched Pioneer 10 toward the outer planets."​

Really? Well, if it wasn't effecting the entire voyage of the spacecrafts, I think we can safely rule out issues with our understanding of gravitation.

Again, I'm totally lost on what you're trying to say here.

One can explain the motions of 7 out of the 8 planets in our solar system using Newton's equations alone, and have a fairly good stab at Mercury's orbit too. Long before Einstein suggested revisions to gravity and his theories of relativity, people were perfectly satisfied that their motions had been explained almost exactly by Newtonian mechanics.

It was only when more precise measurement techniques and more evidence had been gathered and new experiments had been devised that scientists saw there may be scope for revision, relativity emerging from problems with electromagnetic field theories of the late 19th century, and the Einstein field equations for gravity arising out of these.

We know our explanation of gravity is not complete, because we can't explain what happens at Event Horizons of black holes (and how quantum theory relates when small and large scale physics collide).

The Pioneer anomaly could well be evidence of our theory breaking down at the edges, much as Newton's theories broke down when trying to explain new experimental evidence leading to Einstein's work. It could very well be the case our current theories are good approximations that don't explain edge cases, and that experimental data like this might be key to a better theory.

Don't assume that our understanding of anything is perfect and timeless, especially when NASA put Newton, not Einstein, in the driving seat for the vast majority of their intersolar missions because the effects of the EFE revisions are so small they are barely measurable at any reasonable precision or scale, especially when talking about the inexact nature of space probe missions (which have surprisingly high degrees of uncertainty in orbits, slingshots, and so on).

And the Pioneer spacecrafts were the first to start reaching the boundaries of our Sun's influence. We know that the Sun is moving through space, but we have almost no idea what the interstellar medium might be like. Or how it might be moving relative to our solar system.

Dude, you should read up on the Michelson–Morley experiment. The ideas of a luminferous aether (interstellar medium) went out in 1887.

Read A Brief History of Time or one of the countless other layman-orientated books on modern (astro)physics if you're interested.

As for scientific journalism, there will always be a place for slightly sensationalist articles like this, even if they say nothing substantive. The bleeding edge of physics is nearly impossible for the average man to grasp, but we must continue to try and make it accessible, otherwise we'll simply lock physicists in an impenetrable ivory tower that will not only serve to discourage youngsters from joining the field, but will also discourage adults from listening to the important results that physics produces from time to time.

My point is, though, don't roll your eyes at an article because you consider it to be overly summarized or sensationalist, if you want to read the academic paper, then do so, but you can't expect everyone else to do so and understand it. This is why New Scientist sells more copies than Nature, and a Brief History of Time is a NYT bestseller when Gravitation by Misner, Thorne, Wheeler & Wheeler lies at the bottom of the proverbial physics bargain bucket.

 

[bryce]

The Capitan of a Klingon Bird of Prey used them for target practice.

 

[Shaw]

Dude, you should read up on the Michelson–Morley experiment. The ideas of a luminferous aether (interstellar medium) went out in 1887.

Read A Brief History of Time or one of the countless other layman-orientated books on modern (astro)physics if you're interested.

If you are an example of what those layman-orientated books (and layman-orientated articles) produce, then I'll stick with the standard text and papers in this area.

I mean you obviously have no idea what I meant by interstellar medium (which is odd, as it isn't exactly the most technical of terms), so with you as the standard barer for an education from such writings on astrophysics, I can promise you that there will be a lot more rolling eyes at such articles (and books) in the future as I recall your performance here today.



By the way Gravitation is by Misner, Thorne & Wheeler... anyone who has this text knows that there is only one author named Wheeler for that book. And at $115 (what I paid in 1989 for the soft cover edition), I would hardly call that from the bargain bucket.

____________​

Well, beyond that bizarre set of comments from the peanut gallery, I did take a little more time to go through the paper on this stuff. And yes, time dilation has been brought up as a possibility.

But more importantly, the effect is not constant... that is it didn't start with the beginning of the mission, in fact the paper says that the effect doesn't appear until between 10 AU to 20 AU out from the Sun (so just past the orbit of Saturn) and the current outer most boundary of the effect is at 70 AU.

So like I said before, if the effect isn't constant, then odds are that some other explanation other than gravity is at play here.

I would have thought it might be from the bow shock of the solar system moving through the galaxy, but as archeryguy1701 pointed out, the effect seems to be symmetrical which would appear to rule it out.

What is quite odd is that the effect hasn't shown up on other spacecraft. Neither of the Voyager spacecraft are exhibiting this issue and they are well within the range of where the effect started with the Pioneer spacecraft.

 

[Verteron]

If you are an example of what those layman-orientated books (and layman-orientated articles) produce, then I'll stick with the standard text and papers in this area.

Actually I hold a Theoretical Physics degree from Cambridge (and large numbers of people here can testify to my truthiness if necessary) although I haven't been involved in the field for some years, so I'm really quite fuzzy now on the specifics of a lot of things I previously knew lots about. It's the passage of time, see.

I mean you obviously have no idea what I meant by interstellar medium (which is odd, as it isn't exactly the most technical of terms), so with you as the standard barer for an education from such writings on astrophysics, I can promise you that there will be a lot more rolling eyes at such articles (and books) in the future as I recall your performance here today.

I'm grown-up enough to admit when I've made a mistake in transposing the terms 'interstellar medium' and the idea of interstellar aether.

Are you grown-up enough to discuss things with me without resorting to strawman arguments about my perceived lack of education and/or rolling your eyes?

By the way Gravitation is by Misner, Thorne & Wheeler... anyone who has this text knows that there is only one author named Wheeler for that book. And at $115 (what I paid in 1989 for the soft cover edition), I would hardly call that from the bargain bucket.

I'm sorry if my point was too subtle for you. The key here was the insertion of the word 'proverbial'.

What I'm saying is that Gravitation and other 'famous' hard-core physics books have not received anywhere near the economic success and acclaim that BHOT has (have you ever seen it on the NYT bestsellers' list?)

Attitudes like yours are everything I've come to expect from decades of Physics teaching by professors who are more concerned with having their equations sum to zero than recounting their results to the public. I can't think of any other field in science or engineering that has been given such an enormous scope as astrophysics and cosmology over the last 10 years to go off on such a ridiculous and unproductive tangents as you have, when every other field seems to actually be producing beneficial technology.

This attitude is as self-defeating as it is unreasonable, as without the critical link between theoretical results and inspirational explanations that can be read by the man on the street and his kids, pretty soon there isn't going to be any interest in your field and no more little astrophysicists growing up to join the crusade.

Perhaps if more college research astrophysicists were forced to explain how exactly their results were benefitting mankind and furthering the cause of science and make their grant money dependent on it, they might be more willing to drop the condescending attitude and devote more time to clueing in us 'proles' in the activities of 'the party'.

 

[Shaw]

Verteron, I've spent huge amounts of my time and energy in helping others understand the physical world around us... after all, what is the point of knowing anything if you can't share it.

But lets settle things first... I'm grown up enough not to have attacked you unprovoked, and it would have been wonderful to have you join the discussion without starting it off with a personal attack on me. If you are worried about me using strawman arguments like implying a deficiency in your education, then you should not provide me with the motivation by suggesting that I should read A Brief History of Time or one of the countless other layman-orientated books on modern (astro)physics (the exact type of strawman arguments you are requesting me to be grown up enough not to use against you).


Now that we have that aside... have you downloaded the paper and did anything of interest catch your eye? The Voyager data (or lack there of) was something I thought was note worthy.

 

[TerriO]

Can we please try to dial the antagonism back to about half? We have a lot of well-educated people in this forum, and it would be good for everyone to remember that while you yourself may be (or think yourself to be) well-versed on a subject, someone else might think themselves well-versed as well.

I understand where both of you are coming from, but I'm getting the feeling that some egos are getting in the way. You're both bright, intelligent people, and I truly believe this discussion can continue if everyone remembers that perhaps your expertise isn't the be-all, end-all on the subject. Which would you rather be on the receiving end of, an "I'm smarter than you, and this is why" lecture (which, trust me, I hate probably as much as anyone here), or someone genuinely pointing out where your expertise might be lacking and passing on ways to expand that knowledge?

We have a group of very smart people here. Talk with them as you'd like to be spoken to, and from what I've seen so far, you'll find your discussions go a lot easier. And you might even learn something along the way.

So let's just everyone step back, take a breath, and remember that there are human beings with intelligence and experience on the other side of the keyboards here, please?

Thanks.

 

[USS Fardell]

Not exactly time dilation, but the opposite, time speeding up for Pioneer as it moves away from the Solar System and the Sun's gravitational influence.

 

[Verteron]

Verteron, I've spent huge amounts of my time and energy in helping others understand the physical world around us... after all, what is the point of knowing anything if you can't share it.

But lets settle things first... I'm grown up enough not to have attacked you unprovoked, and it would have been wonderful to have you join the discussion without starting it off with a personal attack on me. If you are worried about me using strawman arguments like implying a deficiency in your education, then you should not provide me with the motivation by suggesting that I should read A Brief History of Time or one of the countless other layman-orientated books on modern (astro)physics (the exact type of strawman arguments you are requesting me to be grown up enough not to use against you).

Fine. I was just trying to be helpful, because I was totally confused about your comments about it being wrong to bring Einstein in to an article about gravity anomalies (which I still think is a strange thing to say...).

This led me to believe this was because you (like many others I've spoken to over the years) didn't realised Einstein had worked on gravity. Most people only know about E=mc^2 and maybe a few words about relativity. This was the motivation behind my suggestion of reading an introduction to astrophysics book, not any kind of assault on your intelligence.

So, I apologize if my incorrect assumption led to you being offended, although hopefully you can see the pattern of cause and effect that has led us to this discord.

That said, I still say you're being overly harsh saying it's incorrect to bring big E in to a popular press gravity article.

Now that we have that aside... have you downloaded the paper and did anything of interest catch your eye? The Voyager data (or lack there of) was something I thought was note worthy.

I suppose now's a good a time as any to take a look!

I have read about this before on both a technical and non-technical level, and I certainly did find the lack of any detectable effects from other spacecraft to be very noteworthy. It certainly seems overzealous at this point to start doubting our current best understanding of gravitation on the Pioneer evidence alone, although plugging numbers in to formulas in case further evidence comes to light seems eminently sensible.

 

[Shaw]

Fine. I was just trying to be helpful, because I was totally confused about your comments about it being wrong to bring Einstein in to an article about gravity anomalies (which I still think is a strange thing to say...).

This led me to believe this was because you (like many others I've spoken to over the years) didn't realised Einstein had worked on gravity. Most people only know about E=mc^2 and maybe a few words about relativity. This was the motivation behind my suggestion of reading an introduction to astrophysics book, not any kind of assault on your intelligence.

So, I apologize if my incorrect assumption led to you being offended, although hopefully you can see the pattern of cause and effect that has led us to this discord.

That said, I still say you're being overly harsh saying it's incorrect to bring big E in to a popular press gravity article.

Sure... just as long as you understand why I would never assume that you had any physics background (at all) if you are unfamiliar with the Schwarzschild Solution:

And that it would never even enter my mind that someone with a Theoretical Physics degree from Cambridge would think that someone who is not only talking about General Relativity, but is also talking about one of it's first major applications in the field of cosmology wouldn't know that Einstein put forward General Relativity.

I mean how was I supposed to know that someone with a Theoretical Physics degree would miss all those huge clues and assume that I needed a layman-orientated book on the subject? It seemed quite apparent to me at the time that between missing those clues and your transposing the terms that you must have received your physics education from those same layman-orientated books on the subject. But, as you pointed out, the passage of time (and it's unkind effect on you) could easily explain all that.

So your apology is accepted (and returned) in the obvious spirit in which it was given.


As for my criticism of articles which need to put Einstein's name in the headline... I'm sure that anyone who would think that it is not a gimmick also has no problem with children who cry wolf.

 

[Saturn0660]

Fine. I was just trying to be helpful, because I was totally confused about your comments about it being wrong to bring Einstein in to an article about gravity anomalies (which I still think is a strange thing to say...).

This led me to believe this was because you (like many others I've spoken to over the years) didn't realised Einstein had worked on gravity. Most people only know about E=mc^2 and maybe a few words about relativity. This was the motivation behind my suggestion of reading an introduction to astrophysics book, not any kind of assault on your intelligence.

So, I apologize if my incorrect assumption led to you being offended, although hopefully you can see the pattern of cause and effect that has led us to this discord.

That said, I still say you're being overly harsh saying it's incorrect to bring big E in to a popular press gravity article.

Sure... just as long as you understand why I would never assume that you had any physics background (at all) if you are unfamiliar with the Schwarzschild Solution:

And that it would never even enter my mind that someone with a Theoretical Physics degree from Cambridge would think that someone who is not only talking about General Relativity, but is also talking about one of it's first major applications in the field of cosmology wouldn't know that Einstein put forward General Relativity.

I mean how was I supposed to know that someone with a Theoretical Physics degree would miss all those huge clues and assume that I needed a layman-orientated book on the subject? It seemed quite apparent to me at the time that between missing those clues and your transposing the terms that you must have received your physics education from those same layman-orientated books on the subject. But, as you pointed out, the passage of time (and it's unkind effect on you) could easily explain all that.

So your apology is accepted (and returned) in the obvious spirit in which it was given.


As for my criticism of articles which need to put Einstein's name in the headline... I'm sure that anyone who would think that it is not a gimmick also has no problem with children who cry wolf.

Dude thats like second grade math...

 

[Timo]

Dunno... If this "discussion" has had any effect on people in need of education on the subject matters relating to Pioneer drift, it would seem to boil down to:

-Avoid contact with an expert at all costs unless you are on level with him to begin with (but can act suitably humble/reverent about it).

-Never look into science articles because they don't tell the whole truth.

-Certainly never confess to getting interested in a topic before you can quote a high-impact reference.

I hope there are several valid ways to go with "helping others understand the physical world around us", because this one doesn't seem to be working too well. It probably does help people understand the inner workings of science (and education) as a profession, tho.

Timo Saloniemi