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Mysterious Force Affects Pioneer 10 & 11 Probes
JabbaTheFart writes "The Guardian is writing that something strange is tugging at America's oldest spacecraft. As the Pioneer 10 and 11 probes head towards distant stars, scientists have discovered that the craft - launched more than 30 years ago - appear to be in the grip of a mysterious force that is holding them back as they sweep out of the solar system.
Some researchers say unseen 'dark matter' may permeate the universe and that this is affecting the Pioneers' passage. Others say flaws in our understanding of the laws of gravity best explain the crafts' wayward behaviour."
The question is can we develop the technology to detect tractor beams all the way out there from here?
What's interesting about this is the craft went in different directions out of the solar system, which rules out something like the mass of an unknown body in the outer solar system affecting their flight.
Please read my Canon EOS tech blog at http://www.everyothershot.com
exactly what was AFFECTED?
They could just be hitting up against that big crystal shell that all the stars are painted on.
Smeghead every day of the week.
When you think about it, we know so little about deep space. Perhaps the Matrix doesn't go out that far? Clipping problems?
It is also thought that dark matter is at the centre of galaxies Could explain a lot of things, e.g. the expansion/contraction of the universe. Judging by the amount of "tangible" matter in the universe, there is no way to halt the expansion, and it will go on forever. However, if there is dark matter, it could hold enough gravity to halt expansion and force the big crunch. Lots of info on this sort of stuff here
It is neat to see things like this which challenge our understanding of relatively basic things like gravity. Part of me is still hopeful that we will find some holes in the relativity theory. More than a few scientists have pointed out other inconsistencies between observations and relativity. It would be nice not to be constrained by this whole 186,000 miles per second thing :)
Ah yes, the good old "If you don't know, blame it on Dark Matter" strikes again.
-Kenneth Sundby-
Note to Hemos: The verb is spelled "affect". You know, with an "a". The noun is spelled "effect", but it's the verb needed in the title.
Sorry, don't mean to sound curmudgeonly and grumpy and so forth, but so few people get this right that I can't stand by and let it slide.
I'll put the cantankerous old grouch away now...
Daar is nie 'n lepel nie
Bit of an old story this.
wot no sig
Only if by "rare" you mean "all the time."
The Bush Administration is altering the laws of gravity in order to distract us from the situation in Iraq. A bill in Congress right now will nullify the law of gravity as we know it, taking away the rights of individuals to remain firmly planted on the Earth.
Link to the Physics Web article: http://physicsweb.org/article/world/17/9/3
RELEASE: 03-082HQ PIONEER 10 SPACECRAFT SENDS LAST SIGNAL After more than 30 years, it appears the venerable Pioneer 10 spacecraft has sent its last signal to Earth. Pioneer's last, very weak signal was received on Jan. 22, 2003. NASA engineers report Pioneer 10's radioisotope power source has decayed, and it may not have enough power to send additional transmissions to Earth. NASA's Deep Space Network (DSN) did not detect a signal during the last contact attempt Feb. 7, 2003. The previous three contacts, including the Jan. 22 signal, were very faint with no telemetry received. The last time a Pioneer 10 contact returned telemetry data was April 27, 2002. NASA has no additional contact attempts planned for Pioneer 10.
Bush Lies On the Record.
It's a SPACE STATION!!!
For those that would die defending it, Freedom
has a sweet taste that the protected will never know.
I have no idea whether the effect would be so big though.
Some (Majorana?) even thought some kinds of matter were radiating "pushing gravity", but I'm really leaning dangerously far out of the window by guessing that this is the way that a black hole a the center of the galaxy causes the anomaly in galactic rotation curve that is observed (that anomaly suggests more (gravitational) pull, too.)
Please note that the arguments derived from thinking about Pushing gravity might apply even if gravity is not considered pushing by the physics used.
I'm still trying to figure out what people mean by 'social skills' here.
After reading the article I had a flashback about old computer games, where "mysterious force" would tug you back when you reached the end of the area.
:)
How funny it would be if our world ended after Pluto and the stars would only be 'a painted backcloth'. I wonder what kinda effect it would have on our society. Scientist would propably spend years trying to explaing the phenomena, until one day a human could travel to the edge and verify the obvious.
Or maybe the aliens that run our world on their supercomputer have not yet coded the rest of the universe. Let's wait for few more years and see if 'the mysterious force' has been removed
Has this effect been observed as to the Voyagers?
Excellent illustration (updated daily!) of all these probes and their vitals (trajectories, distance, speed, etc.) at Heavens-Above .
Bush Lies On the Record.
Setting your speed at "c" and it takes a while to get out of the Solar System. Set it at a few AUs per second and you can clear the solar system more quickly, but once you are out, it seems like you are not moving at all. Once you accelerate to a light year per second, things start moving a bit, especially the neighboring stars, but it is still pretty slow going on a galactic scale. If you want to get out beyond the galaxy, I recommend going perpendicular to the galactic plane and accelerating to a few thousand light years per second (ummm...that is rather fast, don't you think).
Doing this gives you a pretty good perspective on things. Once you are in inter-galactic space, if you aren't moving about a thousand light years per second, it seems like you aren't moving at all. For an even better perspective of mixing size and speed, try manually flying back to Sol. It seems easy, and you even decelerate a bit, but it seems like you are going kind of slow until you suddenly zip past Sol doing about 100 light years per second. Go back and try again.
Back to the original point, yeah the speed of light is fast, but on a galactic and/or universal scale, it isn't that fast. I too hope they either find some loopholes in relativity, or find some loopholes in the universe (such as Asimov's idea of Hyperspace), or we won't be going anywhere anytime soon.
Yeah, I know this is deeply in the realm of Science Fiction, but I'm kind of hoping that it becomes Science Fact someday...
"Empathise with stupidity, and you're halfway to thinking like an idiot." - Iain M. Banks
As it happens, The Economist recently ran an article addressing some of these issues. The article also provides context and perspective that should be of interest to those participating in this discussion. For convenience, the full text is reproduced below; it is also accessible online (may require paid subscription).
----
Gravitational anomalies
An invisible hand?
Aug 19th 2004
From The Economist print edition
[Image]
An unexplained effect during solar eclipses casts doubt on General Relativity
"ASSUME nothing" is a good motto in science. Even the humble pendulum may spring a surprise on you. In 1954 Maurice Allais, a French economist who would go on to win, in 1988, the Nobel prize in his subject, decided to observe and record the movements of a pendulum over a period of 30 days. Coincidentally, one of his observations took place during a solar eclipse. When the moon passed in front of the sun, the pendulum unexpectedly started moving a bit faster than it should have done.
Since that first observation, the "Allais effect", as it is now called, has confounded physicists. If the effect is real, it could indicate a hitherto unperceived flaw in General Relativity--the current explanation of how gravity works.
That would be a bombshell--and an ironic one, since it was observations taken during a solar eclipse (of the way that light is bent when it passes close to the sun) which established General Relativity in the first place. So attempts to duplicate Dr Allais's observation are important. However, they have had mixed success, leading sceptics to question whether there was anything to be explained. Now Chris Duif, a researcher at the Delft University of Technology, in the Netherlands, has reviewed the evidence. According to a paper he has just posted on arXiv.org, an online publication archive, the effect is real, unexplained, and could be linked to another anomaly involving a pair of American spacecraft.
Three different types of instrument have been used to detect the Allais effect. The first are conventional pendulums, such as the one Dr Allais used originally. The second are torsion pendulums, which work by hanging a bar that has weights at each end from a wire. As the wire twists back and forth, the bar rotates in pendulum-like motion. The third are gravimeters, which are, in essence, very precise scales. All of these instruments measure the acceleration due to gravity at the Earth's surface, a quantity known as g. The Allais effect is a small additional acceleration, so tiny that it would take an apple about a day to fall from a tree branch if it were the only gravitational effect around.
Allez, Allais
Dr Duif has examined various conventional explanations for the Allais effect. He finds the most obvious suggestion--that it is a mere measuring error--unlikely, because similar results have been found by many different groups, operating independently and, in at least one case, without knowledge of Dr Allais's results.
He also discounts several explanations that rely on conventional physical changes that might take place during an eclipse. One of these is that the anomaly is caused by the seismic disturbance induced as crowds of sightseers move into and out of a place where an eclipse is visible. That seems unlikely, given that one of the experiments with a positive result was conducted in a remote area of China while another that had a negative result took place in Belgium, one of the most crowded parts of the planet. Dr Duif also considered the possibility that, because the moon's shadow cools the air during an eclipse, this cooler, and thus denser, air might exert a different gravitational pull on the instruments. This change could, he reckon
And why wasn't it seen until now? And why did it start effecting the two craft at the same time? Provide a few more details of the radiation pressure hypothesis, or better a few links and I'll be more apt to believe you. Until then I remain skeptical. The Pioneer Anomaly has been around for a little while, long enough to generate more than a few ( Google Search of Citebase)) papers written to try to explain the anomaly. Dismissing them all out of hand in two sentences is NOT good science, but then hey, this is Slashdot, what do I expect?
What if it is just turtles all the way down?
It is most certainly not radiation pressure from the RTGs. If you would care to read the original 54 page article gr-qc/0104064 at http://arxiv.org/ you would have noticed that the original authors took serious effort to account for the radiation pressure from the RTGs and could make it in no way large enough to account for the anomaly.
Hmm, I've read about this on Slashdot before, and I'm pretty sure I've read about Modified Newtonian Dynamics before.
The gist is this: MOND is an alternative to the "dark matter" explanation. It makes a modification to newton's laws of motion, whereby gravitational strength.
The equation F = ma is well known, but with MOND the gravitational inverse square law changes to an inverse linear law when the acceleration due to gravity falls below a critical value, which is very small (i.e. you get pretty far away from the source of gravity).
This explains most of the observed behavior that is currently explained by dark matter, including the rotation of galaxies which seem to defy newton's laws. Unfortunately, there's still no derived theoretical basis for MOND; as of now it's a rather arbitrary explanation with equations that just seem to work pretty well, and many physicists do not take MOND seriously. Then again, "dark matter" seems just as silly.
A more in-depth explanation is available here.
Interestingly, the MOND critical value for the acceleration (a0) turns out to be the speed of light divided by the age of the universe.
-CausticPuppy "Of all the people I know, you're certainly one of them." -Somebody I don't know
The key issue here is that the verb "to effect" is meaningful and useful, and we are rapidly losing it through ignorant misuse. One can advocate a descriptive rather than prescriptive approach to language, but that isn't the same as defending actual errors in widely-understood words. Saying "effect" when you mean "affect" isn't like saying "ain't" when you mean "isn't", it's like saying "Austria" when you mean "Australia".
I like the following explanation of the anomalous acceleration. No dark matter/20 dimensions/new gravity theory needed here. A small amount of dust in the kuiper-belt that transfers momentum with the probe should be enough to explain the slowdown. Look at: http://www.newtonphysics.on.ca/Anomalous/Accelerat ion.html
True that. Admitting uncertainty is the first step of science..."we don't know for sure why this is, so we'll propose a hypothesis, test it, and if the results don't clarify anything, we'll propose another one."
I don't know why people are shocked, or take it as a sign of supernatural causes every time a scientist "isn't sure." They're never sure. If they were sure, they wouldn't be scientists. Science takes a certain amount of confidence in a possibility, but being "sure" is the first step towards fudging data that's inexplicable. The universe is infinitely large and thus infinitely complex, and we'd only been empirically studying it for a few thousand years. Most of our in-depth insights have taken place in the past 200 years, and many clarifications and exceptions have taken place in the past 50, and even the past 20.
Scientists have a notoriously matter-of-fact attitude that leads some people to believe that science believes itself to be infallible. It doesn't. But due to the need for strict controls, even on language, to avoid confusion between scientists, even false and preposterous assumptions need to be stated matter-of-factly. Scientists don't claim to have all the answers...they just claim to have some very realistic (and repeatable) ones.
Hey freaks: now you're ju
So, we have to raise the Yamato, outfit her with a Wave Motion Gun, and go out there and whup that ass!
I didn't think the house band in Hell would play this badly.
Affect and effect are two different verbs, with related but quite different meanings.
Affect is the more common. To affect something is to alter it, usually but not always in a harmful way.
Effect is less common. To effect something is to cause it to happen. I noticed people starting to use this more commonly about eight years ago. Soon afterwards, people started to use the verb "to effect" instead of the verb "to affect", unaware of the difference in meaning. The difference is so strong that these people often end up saying the opposite of what they mean.
here is a good reference.
http://www.spacedaily.com/news/voyager1-03c.html contains some interesting data that may be a clue:
:-) ).
"The location of the heliopause, which marks the outermost edge of the solar system, is a subject of scientific speculation. In two papers recently published in the journal Nature, scientists debated whether Voyager 1 has already reached the termination shock, a sign that the heliopause may be near. The termination shock is caused by a reduction in the speed of the solar wind as it slams into cooler plasma at the edge of the solar system and is similar to the sonic boom that occurs on Earth when an airplane crosses the sound barrier."
So my guess (IANAAP) is they have lost their (solar) wind in the back they had and hence the decceleration. It may not be so simple, though. Perhaps the space on the inside of the heliopause sphere is constantly "sweeped" by solar wind and therefore might have lower density then surroundings (picture: we are in a kind of a solar bubble!
There is a way to put my hypotesis to test: check the temperature readings for signs of friction, or perhaps even cooling.
Er, no, actually. What's your point?
My point was to use a stereotype to poke fun at a random stranger, thereby bolstering my own sense of self-worth by deflecting attention away from my own, numerous insecurities and enormous sense of inadequacy. This is quite common on slashdot; people usually get modded up for it. Hope you didn't take it personally...
Everyone seems to be operating under the assumption that a force is acting to push the probes closer. What better describes what is going on is that the probes are no longer being influenced by an outward force (perhaps solar wind). So lets say theoretically that the sun's gravity as we observe it is Gsun. But with this additional force now detected, we're really seeing Gsun = Gactual - Fnew.
The laws of physics don't just stop working. More likely, we just aren't observing the phenomenon correctly.