9 ms·

Pioneer Anomaly Solved By 1970s Computer Graphics Technique

218 points by iuguy 16y ago

jarin 16y ago
Doesn't it seem like a slowdown caused by infrared light emitting from one part of Pioneer and reflecting off of another part of Pioneer is kind of like powering a sailboat with a giant fan attached to the back of the sailboat? I'm not a physicist by any means, but doesn't conservation of momentum apply to photon emission and absorption/reflection as well?
- deleted 16y ago
  [deleted]
- dexen 16y ago
  The original direction of the (infrared) light is irrelevant, only the end result matters -- the `net force', with reflections and losses factored in. And factoring in the reflections is exactly what the article is about. So it's not like a sailboat with a fan, more like a jet airplane with thrust reversers [1] engaged. While the original thrust is ordinarily pointed rearwards, it's redirected when the reversers are engaged and the `net force' (original thrust sans losses) is pointing frontwards. ---- [1] http://en.wikipedia.org/wiki/Thrust_reverser http://en.wikipedia.org/wiki/Thrust_reverser
  - jarin 16y ago
    Ah, that totally makes sense. Apologies if that was a dumb question, I am a high school dropout after all. :)
  - ars 16y ago
    The reason it's like a jet engine is that the engine "creates" wind - by burning fuel, the hot exhaust is the new wind. If a jet engine only moved wind (like a turbo prop), then a thrust reverser would not work.
    - dexen 16y ago
      EDIT: wait, what? I'm convinced that thrust reverser would (in principle at least, construction details be damned) work with a propeller engine. In my understanding, even if the air stream was accelerated rearwards at first, and only subsequently redirected frontward, it'd still create net force pointing frontward (decelerating one), without need for increased temperature nor extra mass from burned fuel. But I don't have solid physic background; somebody please correct me. It may be easier to visualize it with a ducted fan. As used on some RC aircraft models, modeled after jet-engined crafts. I believe a thrust reverser would work in such a setup, minus friction and turbulent losses.
      - falcolas 16y ago
        With a propeller engine, the "wind" is a side effect caused by to the primary effect of the props getting "lift" in the forward direction, similar to how the wings themselves work. The prop itself is a wing [1], which twists to create even thrust across the prop despite the speed differences between the root and tips. Turbofans (and ducted fans) are different, as they really do produce thrust due to the particles they are throwing backwards (direct thrust).[2] Turboprops can get reverse thrust by inverting the propellers, but adding a thrust reverser behind them would not be enough to negate the forward lift (though they could cause problems with the airflow over the props that would negate the forward lift - but it wouldn't be due to the redirected airflow). [1] https://secure.wikimedia.org/wikipedia/en/wiki/Propeller_%28aircraft%29 https://secure.wikimedia.org/wikipedia/en/wiki/Propeller_%28... [2] https://secure.wikimedia.org/wikipedia/en/wiki/Turbofan https://secure.wikimedia.org/wikipedia/en/wiki/Turbofan
      - ars 16y ago
        Imagine a bent tube in a 'u' shape with a fan in the middle. Both openings of the tube point toward the front of the plane. That's basically what a propeller engine with a thrust reverser is. And I think you can visualize how it will do nothing if you turn on the fan. The force from the air exiting and entering the tube will cancel out.
        eru 16y ago
- ars 16y ago
  You can power a sailboat with a giant fan. What's the problem? Don't point it at the sail though - just point it away from the boat. :) But anyway the difference here is that the "wind" is not being "pulled" from external sources (like real wind), it's created by Pioneer. And that makes a huge difference. With wind, the fan pulls the wind (which creates force), and also pushes the wind (which also creates force). Next you impact the wind into the sail, which subtracts from our force (since the wind is pushing in the wrong direction). And finally the wind "bounces" off the sail, also subtracting, and leaving you with no net force. i.e. +2 then -2. With pioneer one step is missing - the force from pulling the wind (since the photons are created on the fly). So you have +1 then -2, leaving you with a net force of -1. PS. If you don't understand why pulling and pushing the wind counts as two forces, think of a compressor which sucks in air and stores it. It still causes motion by pulling the air, but it doesn't push it.
- omellet 16y ago
  Yes. But the equipment on the back is radiating heat (roughly speaking) in every direction, as I understand it, so absent a reflector, the equipment would have a net zero effect on thrust. But because some of the heat is being reflected, it's contributing a non-zero amount of thrust.
deleted 16y ago
[deleted]
bhickey 16y ago
Wouldn't ambient occlusion have been a better technique?
- CountHackulus 16y ago
  Yeah, I'm not sure that Phong Shading is really the takeaway here. It seems that it's more like they went from a local "illumination" technique to a full global "illumination" technique to take into account secondary bounces.
  - lutorm 16y ago
    This was my impression, too.
- megrimlock 16y ago
  Ambient occlusion (as the term is typically used) is a way to approximate local reflection of uniform inbound (aka ambient) light. It does this by measuring how much of the exterior environment is visible at each point, as a way to modulate an ambient lighting term. It doesn't really simulate how light bounces locally around an object, nor light emitted by an object. Rather than a light transport simulation it's more of a clever CG approximation hack that looks great and is pretty cheap. But to the real point I think you were trying to make: yes, there have been a lot of strides in simulating light since the 70's, and more advanced techniques exist that should give more accurate results.
jvandonsel 16y ago
It's a bit disappointing, actually. I was hoping for another revolution in Newton's laws.
- ars 16y ago
  So was I. But there is still hope - these results have not been verified yet. :)
- CoffeeDregs 16y ago
  Agreed. Against all reason, I was kinda hoping that the Pioneer Anomaly would somehow lead us to FTL travel... Something like: "Hey, I think I figured out the Pioneer Anom... [pause...] Ooooohhhh!"
  - JacobAldridge 16y ago
    Well, the results have yet to be verified. Maybe it still will lead to FTL travel, and someone will solve this problem last year.
- jdavid 16y ago
  I was hopping that this would lead to us sending out plenty of extra-solar-system probes so we could perform more wacky measurements like the pioneer ones. http://www.wired.com/wiredscience/2011/03/vanishing-dimensions/ http://www.wired.com/wiredscience/2011/03/vanishing-dimensio... I think the only qualitative way to guarantee research progress is through the expansion of the things we can sense/ perceive. For example, if we want to understand space better, I don't think another near earth telescope is the answer, but rather several that float at the edge of our solar system. I am also excited about IPN- the Interplanetary Internet by Tim Burners Lee. So that there is a standard way for these crafts to communicate and relay messages as they get really far out. http://www.slideshare.net/vinodquilon/interplanetary-internet http://www.slideshare.net/vinodquilon/interplanetary-interne...
- CWuestefeld 16y ago
  "The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm... that's funny...'" - Isaac Asimov
copper 16y ago
> Of course, other groups will want to confirm these results and a team at the Jet Propulsion Laboratory in Pasadena, which has gathered the data on the probes, is currently studying its own computer model of the thermal budgets. Here's to hoping that the numbers match. Phong shading to calculate numerically the effects of a what is almost a solar sail to decelerate Pioneer - now that's cool science!
- dexen 16y ago
  It also goes to show no scientific research (if performed rigorously and honestly) should ever be derided as being of little use. One wouldn't expect a graphics (!) algorithm to solve a (seemingly) physical problem. Same as one wouldn't expect some obscure branch of algebra to give birth to modern asymmetric cryptography ;-)
  - hollerith 16y ago
    I am not persuaded. You are essentially saying that any attempt to steer (rigorous, honest) research or research funding in the direction of maximum usefulness is futile. Pointing out instances in which predicting the effects of research is tricky does not get you all the way to convincing me of that.
    - dexen 16y ago
      > (...) is futile. A negation of `should not be derided / may turn out to be important' doesn't read `is always unimportant'. I agree with you wholeheartedly pointed research is important. Anyway! Maximum usefulness on what timescale? [1] To judge the impact of future use, you'd pretty much have to both 1) invent all the important uses on the spot, 2) judge the market impact of each -- including any ripple effect and any combination with other, possibly totally unrelated at first, technologies [2]. Good luck with doing that in a reliable way. The honesty of the research itself will be at risk, if there is any incentive in that [3]. ---- [1] E. W. Dijkstra makes some pretty sound comments on timescale of research: http://www.cs.utexas.edu/users/EWD/transcriptions/EWD11xx/EWD1175.html http://www.cs.utexas.edu/users/EWD/transcriptions/EWD11xx/EW... [2] a semiconductor, by itself, is a high impact thing. Computer Science (the theory, without the machines) by itself has little impact on anything. The both combined gives the -- unbelievably transformative -- computer :-) [3] http://en.wikipedia.org/wiki/Oil-drop_experiment#Millikan.27s_experiment_and_cargo_cult_science http://en.wikipedia.org/wiki/Oil-drop_experiment#Millikan.27... -- subsequent scientists, instead of reporting objective results of their experiments, tended to skew the data (more or less unintentionally) towards the original reference value (which was eventually found to be off by a good bit). The only incentive here was consistency -- a pretty subtle one!
PaulHoule 16y ago
This is a classic example of how the physics community has been failing for the last 30 years. First of all, there's an extreme focus on papers that have come out in the last 1.5 years, so that a lot of very interesting older work is invisible. Secondly, physicists don't look outside the discipline, despite the fact that we often use inferior techniques. Back in the 1990's, Mark Newman and I were both working at Cornell and both of us were aware that the techniques physicists were using to evaluate power law distributions were bogus. Well, I was a timid grad student and, despite being one of the best physicists of his generation who already had written half of an excellent textbook and had a stellar research record, Mark was a postdoc who spent most of his two years in absolute anguish about how he was going to find his next job. Mark wrote a paper about this ten years later, after physicists had published thousands of bogus papers using bogus statistics. It's a tragedy that neither Mark, myself or some other young turk didn't write it earlier -- and it wouldn't have been hard to do it all because it would mainly be a review paper of what was already in the statistics literature.
- dexen 16y ago
  > Secondly, physicists don't look outside the discipline, (...) Pardon? Phong shading is a simplified model of results of a physical process -- light reflections off certain kinds of surfaces (metallic ones, IIRC). It's imprecise, it has its limitation etc. Contrast that with the very tiny, precisely measured acceleration of Pioneer spacecrafts. It is not very common to get good results from applying a coarse tool to a fine problem.
  - copper 16y ago
    To nitpick, the discpline of physics covers everything - or it damn well ought to :) While it seems obvious after reading the article that solving the rendering equation is indeed a promising way to solve the Pioneer anomaly, I'm sure that I wouldn't have come up with the idea.
    - eru 16y ago
      > To nitpick, the discpline of physics covers everything - or it damn well ought to Everything in the universe. But there's still math.
Jabbles 16y ago
The key conclusion, with error estimates: We performed 10^4 Monte Carlo iterations, which easily ensures the convergence of the result. The thermal acceleration estimate yielded by the simulation for an instant 26 years after launch, with a 95% probability, is a(t=26) = (5.8 ± 1.3) × 10^−10 ms^-2. ... These results account for between 44% and 96% of the reported value a = (8.74 ± 1.33) × 10^−10 ms^-2 (which, we recall, was obtained under the hypothesis of a constant acceleration) — thus giving a strong indication of the preponderant contribution of thermal eﬀects to the Pioneer anomaly. http://arxiv.org/abs/1103.5222 http://arxiv.org/abs/1103.5222
BoppreH 16y ago
Somebody better update the people using it as an anti-science argument. Edit: I'm serious. Conservapedia used to have an article about it and how it discredits the scientific model and whatnot. There's a huge knowledge gap between this views and we should do our best to eliminate it.
- pohl 16y ago
  For reference: http://www.conservapedia.com/Pioneer_anomaly http://www.conservapedia.com/Pioneer_anomaly
  - JacobAldridge 16y ago
    Interesting - Conservapedia throws me a 403 Forbidden when I try to access that link, and any other of their pages. Anyone else having trouble? (Win 7, FF4, UK based ISP)
    - pohl 16y ago
      I'm getting a tcp error now. It doesn't really matter. It would be much like rushing off to correct the entries in Uncyclopedia and Encyclopedia Dramatica, anyway.
      - BoppreH 16y ago
        But Uncyclopedia and Encyclopedia Dramatica don't claim to hold the universal truth or try to convince people to follow a specific lifestyle based on that. On a site note, my GGP post earned me my 666th karma point. Very suitable.
        pohl 16y ago
        You're probably right about that. Not everybody thinks "reluctant to incorporate new information" when they see the name "Conservapedia" and has a little giggle.
    - MichaelGG 16y ago
pasbesoin 16y ago
What I appreciate about this is the straight-forward manner in which the story presents the case for always challenging your/the assumptions. Speculation about a whole new aspect for theoretical models of the universe. Someone's grounded enough to go over the work and realize, 'Hey, you're doing the math wrong!' I wish science education did a better job of teaching this.
dexen 16y ago
There is a detailed, concise article on how the model was prepared: http://www.planetary.org/programs/projects/pioneer_anomaly/update_20080519.html http://www.planetary.org/programs/projects/pioneer_anomaly/u...

218 points by iuguy 16y ago

jarin 16y ago

Doesn't it seem like a slowdown caused by infrared light emitting from one part of Pioneer and reflecting off of another part of Pioneer is kind of like powering a sailboat with a giant fan attached to the back of the sailboat? I'm not a physicist by any means, but doesn't conservation of momentum apply to photon emission and absorption/reflection as well?

deleted 16y ago
[deleted]
dexen 16y ago
The original direction of the (infrared) light is irrelevant, only the end result matters -- the `net force', with reflections and losses factored in. And factoring in the reflections is exactly what the article is about. So it's not like a sailboat with a fan, more like a jet airplane with thrust reversers [1] engaged. While the original thrust is ordinarily pointed rearwards, it's redirected when the reversers are engaged and the `net force' (original thrust sans losses) is pointing frontwards. ---- [1] http://en.wikipedia.org/wiki/Thrust_reverser http://en.wikipedia.org/wiki/Thrust_reverser
- jarin 16y ago
  Ah, that totally makes sense. Apologies if that was a dumb question, I am a high school dropout after all. :)
- ars 16y ago
  The reason it's like a jet engine is that the engine "creates" wind - by burning fuel, the hot exhaust is the new wind. If a jet engine only moved wind (like a turbo prop), then a thrust reverser would not work.
  - dexen 16y ago
    EDIT: wait, what? I'm convinced that thrust reverser would (in principle at least, construction details be damned) work with a propeller engine. In my understanding, even if the air stream was accelerated rearwards at first, and only subsequently redirected frontward, it'd still create net force pointing frontward (decelerating one), without need for increased temperature nor extra mass from burned fuel. But I don't have solid physic background; somebody please correct me. It may be easier to visualize it with a ducted fan. As used on some RC aircraft models, modeled after jet-engined crafts. I believe a thrust reverser would work in such a setup, minus friction and turbulent losses.
    - falcolas 16y ago
      With a propeller engine, the "wind" is a side effect caused by to the primary effect of the props getting "lift" in the forward direction, similar to how the wings themselves work. The prop itself is a wing [1], which twists to create even thrust across the prop despite the speed differences between the root and tips. Turbofans (and ducted fans) are different, as they really do produce thrust due to the particles they are throwing backwards (direct thrust).[2] Turboprops can get reverse thrust by inverting the propellers, but adding a thrust reverser behind them would not be enough to negate the forward lift (though they could cause problems with the airflow over the props that would negate the forward lift - but it wouldn't be due to the redirected airflow). [1] https://secure.wikimedia.org/wikipedia/en/wiki/Propeller_%28aircraft%29 https://secure.wikimedia.org/wikipedia/en/wiki/Propeller_%28... [2] https://secure.wikimedia.org/wikipedia/en/wiki/Turbofan https://secure.wikimedia.org/wikipedia/en/wiki/Turbofan
    - ars 16y ago
      Imagine a bent tube in a 'u' shape with a fan in the middle. Both openings of the tube point toward the front of the plane. That's basically what a propeller engine with a thrust reverser is. And I think you can visualize how it will do nothing if you turn on the fan. The force from the air exiting and entering the tube will cancel out.
      - eru 16y ago
ars 16y ago
You can power a sailboat with a giant fan. What's the problem? Don't point it at the sail though - just point it away from the boat. :) But anyway the difference here is that the "wind" is not being "pulled" from external sources (like real wind), it's created by Pioneer. And that makes a huge difference. With wind, the fan pulls the wind (which creates force), and also pushes the wind (which also creates force). Next you impact the wind into the sail, which subtracts from our force (since the wind is pushing in the wrong direction). And finally the wind "bounces" off the sail, also subtracting, and leaving you with no net force. i.e. +2 then -2. With pioneer one step is missing - the force from pulling the wind (since the photons are created on the fly). So you have +1 then -2, leaving you with a net force of -1. PS. If you don't understand why pulling and pushing the wind counts as two forces, think of a compressor which sucks in air and stores it. It still causes motion by pulling the air, but it doesn't push it.
omellet 16y ago
Yes. But the equipment on the back is radiating heat (roughly speaking) in every direction, as I understand it, so absent a reflector, the equipment would have a net zero effect on thrust. But because some of the heat is being reflected, it's contributing a non-zero amount of thrust.

deleted 16y ago

[deleted]

bhickey 16y ago

Wouldn't ambient occlusion have been a better technique?

CountHackulus 16y ago
Yeah, I'm not sure that Phong Shading is really the takeaway here. It seems that it's more like they went from a local "illumination" technique to a full global "illumination" technique to take into account secondary bounces.
- lutorm 16y ago
  This was my impression, too.
megrimlock 16y ago
Ambient occlusion (as the term is typically used) is a way to approximate local reflection of uniform inbound (aka ambient) light. It does this by measuring how much of the exterior environment is visible at each point, as a way to modulate an ambient lighting term. It doesn't really simulate how light bounces locally around an object, nor light emitted by an object. Rather than a light transport simulation it's more of a clever CG approximation hack that looks great and is pretty cheap. But to the real point I think you were trying to make: yes, there have been a lot of strides in simulating light since the 70's, and more advanced techniques exist that should give more accurate results.

jvandonsel 16y ago

It's a bit disappointing, actually. I was hoping for another revolution in Newton's laws.

ars 16y ago
So was I. But there is still hope - these results have not been verified yet. :)
CoffeeDregs 16y ago
Agreed. Against all reason, I was kinda hoping that the Pioneer Anomaly would somehow lead us to FTL travel... Something like: "Hey, I think I figured out the Pioneer Anom... [pause...] Ooooohhhh!"
- JacobAldridge 16y ago
  Well, the results have yet to be verified. Maybe it still will lead to FTL travel, and someone will solve this problem last year.
jdavid 16y ago
I was hopping that this would lead to us sending out plenty of extra-solar-system probes so we could perform more wacky measurements like the pioneer ones. http://www.wired.com/wiredscience/2011/03/vanishing-dimensions/ http://www.wired.com/wiredscience/2011/03/vanishing-dimensio... I think the only qualitative way to guarantee research progress is through the expansion of the things we can sense/ perceive. For example, if we want to understand space better, I don't think another near earth telescope is the answer, but rather several that float at the edge of our solar system. I am also excited about IPN- the Interplanetary Internet by Tim Burners Lee. So that there is a standard way for these crafts to communicate and relay messages as they get really far out. http://www.slideshare.net/vinodquilon/interplanetary-internet http://www.slideshare.net/vinodquilon/interplanetary-interne...
CWuestefeld 16y ago
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm... that's funny...'" - Isaac Asimov

copper 16y ago

> Of course, other groups will want to confirm these results and a team at the Jet Propulsion Laboratory in Pasadena, which has gathered the data on the probes, is currently studying its own computer model of the thermal budgets. Here's to hoping that the numbers match. Phong shading to calculate numerically the effects of a what is almost a solar sail to decelerate Pioneer - now that's cool science!

dexen 16y ago
It also goes to show no scientific research (if performed rigorously and honestly) should ever be derided as being of little use. One wouldn't expect a graphics (!) algorithm to solve a (seemingly) physical problem. Same as one wouldn't expect some obscure branch of algebra to give birth to modern asymmetric cryptography ;-)
- hollerith 16y ago
  I am not persuaded. You are essentially saying that any attempt to steer (rigorous, honest) research or research funding in the direction of maximum usefulness is futile. Pointing out instances in which predicting the effects of research is tricky does not get you all the way to convincing me of that.
  - dexen 16y ago
    > (...) is futile. A negation of `should not be derided / may turn out to be important' doesn't read `is always unimportant'. I agree with you wholeheartedly pointed research is important. Anyway! Maximum usefulness on what timescale? [1] To judge the impact of future use, you'd pretty much have to both 1) invent all the important uses on the spot, 2) judge the market impact of each -- including any ripple effect and any combination with other, possibly totally unrelated at first, technologies [2]. Good luck with doing that in a reliable way. The honesty of the research itself will be at risk, if there is any incentive in that [3]. ---- [1] E. W. Dijkstra makes some pretty sound comments on timescale of research: http://www.cs.utexas.edu/users/EWD/transcriptions/EWD11xx/EWD1175.html http://www.cs.utexas.edu/users/EWD/transcriptions/EWD11xx/EW... [2] a semiconductor, by itself, is a high impact thing. Computer Science (the theory, without the machines) by itself has little impact on anything. The both combined gives the -- unbelievably transformative -- computer :-) [3] http://en.wikipedia.org/wiki/Oil-drop_experiment#Millikan.27s_experiment_and_cargo_cult_science http://en.wikipedia.org/wiki/Oil-drop_experiment#Millikan.27... -- subsequent scientists, instead of reporting objective results of their experiments, tended to skew the data (more or less unintentionally) towards the original reference value (which was eventually found to be off by a good bit). The only incentive here was consistency -- a pretty subtle one!

PaulHoule 16y ago

This is a classic example of how the physics community has been failing for the last 30 years. First of all, there's an extreme focus on papers that have come out in the last 1.5 years, so that a lot of very interesting older work is invisible. Secondly, physicists don't look outside the discipline, despite the fact that we often use inferior techniques. Back in the 1990's, Mark Newman and I were both working at Cornell and both of us were aware that the techniques physicists were using to evaluate power law distributions were bogus. Well, I was a timid grad student and, despite being one of the best physicists of his generation who already had written half of an excellent textbook and had a stellar research record, Mark was a postdoc who spent most of his two years in absolute anguish about how he was going to find his next job. Mark wrote a paper about this ten years later, after physicists had published thousands of bogus papers using bogus statistics. It's a tragedy that neither Mark, myself or some other young turk didn't write it earlier -- and it wouldn't have been hard to do it all because it would mainly be a review paper of what was already in the statistics literature.

dexen 16y ago
> Secondly, physicists don't look outside the discipline, (...) Pardon? Phong shading is a simplified model of results of a physical process -- light reflections off certain kinds of surfaces (metallic ones, IIRC). It's imprecise, it has its limitation etc. Contrast that with the very tiny, precisely measured acceleration of Pioneer spacecrafts. It is not very common to get good results from applying a coarse tool to a fine problem.
- copper 16y ago
  To nitpick, the discpline of physics covers everything - or it damn well ought to :) While it seems obvious after reading the article that solving the rendering equation is indeed a promising way to solve the Pioneer anomaly, I'm sure that I wouldn't have come up with the idea.
  - eru 16y ago
    > To nitpick, the discpline of physics covers everything - or it damn well ought to Everything in the universe. But there's still math.

Jabbles 16y ago

The key conclusion, with error estimates: We performed 10^4 Monte Carlo iterations, which easily ensures the convergence of the result. The thermal acceleration estimate yielded by the simulation for an instant 26 years after launch, with a 95% probability, is a(t=26) = (5.8 ± 1.3) × 10^−10 ms^-2. ... These results account for between 44% and 96% of the reported value a = (8.74 ± 1.33) × 10^−10 ms^-2 (which, we recall, was obtained under the hypothesis of a constant acceleration) — thus giving a strong indication of the preponderant contribution of thermal eﬀects to the Pioneer anomaly. http://arxiv.org/abs/1103.5222 http://arxiv.org/abs/1103.5222

BoppreH 16y ago

Somebody better update the people using it as an anti-science argument. Edit: I'm serious. Conservapedia used to have an article about it and how it discredits the scientific model and whatnot. There's a huge knowledge gap between this views and we should do our best to eliminate it.

pohl 16y ago
For reference: http://www.conservapedia.com/Pioneer_anomaly http://www.conservapedia.com/Pioneer_anomaly
- JacobAldridge 16y ago
  Interesting - Conservapedia throws me a 403 Forbidden when I try to access that link, and any other of their pages. Anyone else having trouble? (Win 7, FF4, UK based ISP)
  - pohl 16y ago
    I'm getting a tcp error now. It doesn't really matter. It would be much like rushing off to correct the entries in Uncyclopedia and Encyclopedia Dramatica, anyway.
    - BoppreH 16y ago
      But Uncyclopedia and Encyclopedia Dramatica don't claim to hold the universal truth or try to convince people to follow a specific lifestyle based on that. On a site note, my GGP post earned me my 666th karma point. Very suitable.
      - pohl 16y ago
        You're probably right about that. Not everybody thinks "reluctant to incorporate new information" when they see the name "Conservapedia" and has a little giggle.
  - MichaelGG 16y ago

pasbesoin 16y ago

What I appreciate about this is the straight-forward manner in which the story presents the case for always challenging your/the assumptions. Speculation about a whole new aspect for theoretical models of the universe. Someone's grounded enough to go over the work and realize, 'Hey, you're doing the math wrong!' I wish science education did a better job of teaching this.

dexen 16y ago

There is a detailed, concise article on how the model was prepared: http://www.planetary.org/programs/projects/pioneer_anomaly/update_20080519.html http://www.planetary.org/programs/projects/pioneer_anomaly/u...