Mystery Force Affecting Probes 296
imipak writes: "The BBC reports that after exchaustive investigations, NASA scientists have run out of possible explanations for the mysterious tiny course deflections experienced by the Pioneer and Voyager spacecraft as they head out of the solar system towards the heliopause. Could it be that there's something wrong with our theory of gravity? (Well, yes, we already know that...) or could it be Oort Cloud objects? The tenth planet? Informed comment, please!"
Re:Possible explanations? (Score:2)
Informed Comment (Score:5)
Slashdot Readers
Hurrah! Please explain it for me, guys. I have a friend at NASA who would really like to know.
Re:Informed Comment (Score:2)
-Paul
Re:Informed Comment (Score:4)
Not to mention that some people might actually like helping their country, despite the fact that folks like you diss all public servants as "also-rans". Because US taxpayers have a screwed-up sense of what public servants deserve, there are some fairly draconian policies in place in various government institutions:
* All cups of coffee must be accounted for, and paid for individually
* No Christmas parties, even if financed by
discretionary money
* Spouses not allowed to ride in government
vehicles, even when travelling together
Obviously, I don't like your attitude. That said, it's quite possible you were making a joke -- an inappropriate joke, in my opinion. How would you like it if your company couldn't hold a Christmas party, despite a year of record performance?
Your comment is certainly not "informed". Consider the following data, all found via Google at
http://www.hq.nasa.gov/office/HR-Education/workfo
* 74% of NASA's workforce have a Bachelor's
degree or higher.
* 34% have a Master's or higher
* 10% have a Doctorate
For an agency with 17,000 employees, that's not bad. How does your company stack up, Mr. Fancy Pants? Here's some more info:
* Average salary across all NASA's scientific
and engineering employees: $79,000
* Average salary across all NASA's employees,
regardless of job: $69,000
* Average salary of scientist or engineer at
NASA's headquarters: $103,000
* Average for same at Ames Research Center:
$86,000
* At all of NASA's centers, scientists and
engineers have higer average earnings than
professional administrators -- music to my
ears!
Remember that these are averages, not maximum salaries. Also, consider that NASA has 17,000 employees, though I don't know how many are scientists or engineers. Given that 35% percent have an advanced degree, this is likely to be a large number. At any rate, these numbers are just fine, if you're not a mercenary.
It is very interesting to look at the top ten reasons people remain federal employees. You can see this list here [reinventing.com].
-Paul Komarek
Re:Invasion of The Mind Snatchers (Score:2)
Okay, more seriously, what the hell are you talking about? It's all abstract voodoo. Have you seen an electron? No, you can't. Electrons and all your beloved particles are invisible. You can see the effects of them, I suppose. But are you really sure it's not fairies doing the real work? Are you really sure it's not God, setting up little games for us to figure out? I mean, if He plants bones in the ground to test our faith, it doesn't seem far fetched that He'd come up with other little games. Or maybe it's multidimensional strings?
You've never seen an atom, not to mention an electron... and certainly not quarks. All that makes you think that they exist is some model, which apparently has been consistent in predicting a wide range of experiments. It's a nice enough model that you have been able to internalize its metaphors, even with only indirect evidence.
But it's just a model made up of a bunch of equations and notions and assumptions. It isn't magic. It isn't Truth. And that model is not somehow endowed with some status that makes it somehow more The True Model than any other mathematical model. Atom theory predicts things good. Newton's theories predict things good. Aristotle was a idiot, and he didn't predict crap, but that's an aside.
So far, no model has predicted and explained everything. Maybe no such model exists, or maybe it does. Maybe many such models exist. You want underlying causes, but you won't get them, ever (unless maybe God is proven to exist). You can only get models. One after another, which by some really long chain of deduction end up in something you can directly sense. Or, at least, you think you can sense, because this all might just be a dream in the mind of Shiva.
It's just turtles, all the way down.
Re:Invasion of The Mind Snatchers (Score:2)
This troll also goes by Nemesis [google.com] on the sci.physics.relativity newsgroup. He's a popular killfile item. He really likes to call people "prevaricating little lapdogs." This means he knows how to use a thesaurus and possibly a dictionary as well. He seems only capable of ad hominem attacks.
Math does not create physics.Ack! He doesn't seem to be able to tell difference between a map and the actual road.
from the Simpsons' Episode: $pringfield (or, How I Learned to Stop Worrying and Love Legalized Gambling):
Mr. Burns - "Quick, Smithers! We'll take the Spruce Goose. Hop in."
Waylon Smithers - "But that's just a model."
Mr. Burns, cocking a revolver - "I said, 'Hop in.'"
On the actual subject of the article: That is simply fascinating. I would like to see them add an experiment to the proposed Pluto probe to study this phenomenon further. Pluto-Kuiper Express [nasa.gov]
Another Possibility (Score:2)
After all, what better way to make contact than to cause an unexplainable error? We'd be sure to notice it!
--
What you ignore... (Score:2)
The field of particle physics that you extol would not exist but for mathematical models.
If "mathematical what-if scenarios" are junk, how do you come up with a falsifiable hypothesis predicting the existense or behaviour of such-and-such subatomic particle? How do you design the experiment to falsify the hypothesis?
Math isn't physics. Math is a tool for modeling. You're a tool for trolling. You may have a legitimate beef with news media who report abstract theory as sensational fact, but I deride the legitimacy of your beef against physicists.
-Isaac
Re:The Paper is here (Score:2)
I think the science instruments would also have detected a change in the velocity of the surrounding medium. It's precisely to detect the heliopause that they are being run.
Of course NASA don't understand gravity (Score:2)
Perhaps the stars really are embedded in a crystal sphere, and the perturbations are the gravitic effects of the sphere beginning to manifest. Watch for a sudden end to transmissions and soon afterwards the mother of all cracks in the sky... (-:
``But seriously, folks''
NASA don't know how our own sun works [electric-universe.de], so how can they be expected to predict behaviour even further away from the sun? How is it that a (ghasp) lone scientist with no resources can bullseye planetary magnetic fields before the fact [icr.org], but NASA (besides many other large and well-equipped organisations) are several orders of magnitude wide of the mark?
Springfield Effect (Score:2)
Clearly, this is due to the Springfield Effect [flat-earth.org]. They have simply passed through new, undiscovered Springfield locations.
Mr. Teapot [flat-earth.org] can answer all your questions.
Re:Invasion of The Mind Snatchers (Score:2)
There is a cult within the spacetime physics community led by a small but influential cadre of nerd physicists and mathematicians whose credo is "physics is math" and who think they are free to create physics simply by manipulating spacetime equations using what-if scenarios.
LOL! That reminds me of Logopolis episode of Dr. Who. This was where the Doctor and the Master visited this city where these people run "block transfer computations" which control reality.
Re:Informed Comment (Score:2)
Perhaps your University's graduate program should offer a course on emoticons and their meaning.
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Probably not an unseen body's gravity. (Score:2)
Oddly enough, it also seems that this deviation is not evident in the orbits of the planets.
Me? I just think that they've been slowed by local debris--though I'd like to believe in a gravitational constant.
-W-
"Is it all journey, or is there landfall?"
Re:Just shows how much more there is than we know (Score:2)
A few comments above we have, "So, let me get this straight. NASA has given up trying to explain this, they have no idea. So for informed comments, now we turn to ...
Slashdot Readers
Hurrah! Please explain it for me, guys. I have a friend at NASA who would really like to know.
I thought it was funny (so did several moderators).
And now we get this obvious troll, and it is moderated as insightful.
Not so funny anymore.
Steve M
Funny? (Score:2)
Its funny (or sad) not flamebait!
Well it sure ain't funny. It may be a sad attempt at humor.
But I'm going with flamebait.
Steve M
String Theory and Gravity (Score:2)
This property is generally seen as a desirable property of the theory. In fact the only really good argument in favor of string theory is that it is the only known quantum mechanical theory which produces the observed behavior of gravity and is not known to have internal inconsistencies.
Probe instrumentation is adequate. (Score:2)
How so?
To start with, the main data of interest (probe positions and trajectories) doesn't require additional instruments to measure. They're looking at the timing and doppler-shifting of the probes' radio signals, and getting a very good estimate of their positions and velocities.
The record of the probes' trajectories over long periods of time is what suggests the effect and places limits on how it acts.
Secondly, there isn't anything *out* there to look at. At least a few of these probes have micrometeorite detectors and dust analyzers and radiation analyzers. That covers just about everything you'll run into. What extra instrumentation do you propose to add?
What kinds of instruments do you think would give us a better idea of what's going on than we already have?
Re:Approximations (Score:2)
The thing is - what happens over large distances? Well, the smaller terms will start to become very important. I've got to wonder if they forgot that the equations they'll typically use ARE approximations which are simplified for ease of use in calculations?
If I understand correctly, the approximations only cause problems in very extreme situations (sharply curved space, very high matter or energy densities, very oddly configured space, etc.). At the probes' location, space is so flat you could treat it with Newtonian mechanics and have a great deal of trouble finding discrepencies with observations.
Thus, I doubt that equation approximations are the cause of the problem in this case.
On the other hand, if I recall correctly there has been interesting speculation about the full versions of the equations allowing negative mass to be generated under some conditions. I'd have to study my relativity book a lot more thoroughly to tell if that's even remotely sane, though.
Re:Could this be the "missing mass" explanation? (Score:2)
If we were only looking at the orbits of the planets about the sun, this would most certainly be correct. However, we've also observed the orbits of the moons of the various gas giants about their primaries, and measured with fanatical precision the paths of the probes we've sent to and past the gas giants. If the mass values for the gas giants were off, this would have very substantial effects on the orbits of their moons and on the trajectories of probes that have visited.
Good thought, though.
Re:Could this be the "missing mass" explanation? (Score:5)
The problem is, as the article points out, we would have seen the effects of this on the orbits of the planets if this was the case.
I'm personally wondering about drift in the probes' radio sources throwing off the doppler measurements, but if this was happening they should have caught it already (you can directly measure the probes' positions by measuring the round-trip signal times to them at a few different imes during the year).
Duh.. (Score:2)
Bullshit, informed? how do you know it's not a bunch of flying winged monkeys. Theories are only slightly better than guesses. Besides, Slashdot isn't exactly the best place to go for people knowledagable in the physics of bodies moving through uncharted portions of space. If you really want informed opinions, try and berate the people at NASA and JPL. Slashdot is more of a jack-of-all-trades thing, theres probably someone with the background similar to Stephen Hawking on here. But the only thing they can offer you is, their opinions and theories. Again, not necessarily better than my theory of tiny space going simians.
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Re:Shape of the universe (Score:2)
Just consider, we don't even know, really, how much "dark matter" there is in either our own galaxy, or in any of the nearby galaxies. But that could profoundly effect the shape of the galaxies. Those who argue that we know that the universe is flat on the order of a mega-parsec (or whatever) actually don't have that much evidence. Just how flat are they asserting it is? And on what fractal scale? (Consider: "How long is a coastline on a fractal scale?" to be the appropriate analogy.) Certainly is must be lumpy near each star or other massive body. The assertion of flatness then is either the assertion that a) that doesn't matter, or b) but it lumps the other way too, so it evens out. Normally we say that is isn't lumpy enough to make any difference, except when we do something like use gravitational lensing. But how exact is our knowledge?
Even things that are straigtforward projections from well known physical laws tend to be scoffed at if they are unfamiliar. Consider the early days of black holes. But they had been predicted in the 1800's (well, not their more peculiar features, but a star that was too heavy for light to escape from). If anybody had run a straightforward calculation (post Einstein) they would have come up with black holes. And they did, but the idea was so strange that nobody would believe it, and it was considered a purely theoretical curiosity. Perhaps there is another "theoretical curiosity" that will explain this. But it's likely to require being willing to accept that the universe isn't a simple as we like to think of it as being.
Caution: Now approaching the (technological) singularity.
Re:Stellar gas? (Score:2)
Caution: Now approaching the (technological) singularity.
Re:Shape of the universe (Score:2)
Bent. Or was that time? I'll have to re-read Dr. Streetmentioner's work again.
--
Oort cloud? (Score:2)
--
Re:Just shows how much more there is than we know (Score:3)
The fact that you can sit in your armchair and question his objectivity, wonder, and *passion* for the mysteries of life makes me physically ill.
Any failing of science is OUR fault. OUR faliere to educate. OUR faliure to recognize our biases. OUR faliures to drag concieted shits like you out of the dark ages.
Re:The Paper is here (Score:5)
(g) and (h) were (in his opinion) the least likely.
Note that the paper was actually first released in April, and just revised today.
Stellar gas? (Score:5)
Here's the deal: On the Earth, the gravitatinal forces acting on you at the surface all sum out to equal to the forces that would be exerted by a point source with the Earth's mass and a distance r, the diameter of the Earth. Though that ocean to your left and that continent to your right pull you in opposite directions, and the ground under your feet is pulling harder than the ground in China (um, unless you're in China, in which case, 'hi'), but it all sums out exactly right to a point mass at radius r.
Now, take that example and pose it to the solar system. Forget about the forc of solar wind blowing, and realize that all that wind has mass, and exists everywhere. It's pretty thin, but it's a lot thicker than the four hydrogen atoms per cubic meter in deep interstellar space. All that stuff, wispy as it is, has mass, and even though most of it is so godawful far away, the net gravitational effect of all of it is as if there were an additional point source inside the sun, with the mass of all the stray gasses and particles inside the huge sphere that has the sun as the center and the space probe on the outer surface.
What makes the math even more wonky is that, assuming a roughly even distribution of gas as inversely proportional (or inverse square, or even constant, doesn't matter in this case as long as it's uniform by uniform radius) to the distance form the sun, then the farther out the probe goes, the more mass there is behind it, and the farther back the point source goes.
If the density were uniform (it's not) then the effect of this force would actually increase as the probe got further away. As it is, it may be a constant force. For conceptualization's sake, if you had a well to the center of the earth and went to the bottom (forget magma, use the moon if it makes you feel better) you'd be weightless. Go halfway up, and you'd have a force of one-half g. Go to the surface and you are being pulled with a stronger force than you were when you were closer to the center.
Anyhow, HTML's bad for math, but I just wanted to get the idea out there. I don't have enough info on particulate density over the scope of the solar system and beyond to make any educated numbers anyhow. Hopefully someone out there does.
Kevin Fox
--
Re:The Paper is here (Score:2)
Gravity is many orders of magnitude less powerful than the other fundamental forces, but at least in our experience gravity is also the only force that is always attractive. It is also one of the forces that has a measurable impact at distances beyond a few angstroms.
If you charge up a baloon with static electricity you can see just how strong the other major fundamental forces are. The number of electrons you're moving around is tiny, but it's enough to overwhelm every single proton, neutron and electron being pulled by gravity. The fact that gravity has a measureable impact isn't anything spooky, it's just the sum of a lot of very weak interactions with no opposing interactions.
Interstellar Medium Density? (Score:3)
The interstellar medium (interstellar gas & dust) is much less dense than normal around our solar system due to the Scorpius-Centaurus Association superbubble [uchicago.edu] and the Geminga supernova bubble [lanl.gov]. Perhaps we're seeing a slight increase in the ISM density -- of course these researchers should know all about this, so it's still a puzzle...
Re:Informed Comment (Score:2)
Approximations (Score:2)
You know... a lot of these problems occur when you take an approximation instead of the real thing.
Eg. Newton's laws are a 1st order approximation to the real thing.
Relativity gets closer.
Now, I can't remember the specifics, but the general equations we use when utilizing relativistic motion are actually still only approximations -- it's just that the third, fourth, etc. order terms of the equation are so small that you can ignore them.
The thing is - what happens over large distances? Well, the smaller terms will start to become very important. I've got to wonder if they forgot that the equations they'll typically use ARE approximations which are simplified for ease of use in calculations?
Simon
Could this be the "missing mass" explanation? (Score:3)
An Explanation (Score:5)
--Fermat
Re:Informed Comment (Score:5)
Re:Shape of the universe (Score:4)
In contrast, the probes are in areas with a relatively small gravitational field. While the field is smaller than anything this side of Pluto's orbit, it's not that much smaller. (The contribution from the sun is lower, but the contribution from the entire Milky Way, and our gravitationally bound galactic cluster, is just as large.) A breakdown in the existing theory just doesn't make sense here - and even if it does break down, where does the energy come from?
As for the issue of the space of the universe... get a grip.
does gravity push and not pull? (Score:5)
it appears that things do slow down over time. The deep space probes are not the only ones showing this. The gps sats are doing it and this is one of the problmes that gravity probe B is suppoed to help solve. I guess it means we have a wrong view of what keeps up stuck on this world.
Informed Comment (Score:2)
Niven readers have understood this for decades (Score:3)
It's Protector Brennan, making slight alternations to make certain that the probes don't eventually travel to planets with possibly-hostile alien species, thereby alerting them to the existence of humans.
Re:They need better instruments, then they might b (Score:2)
Well, there's that hologram doctor... and the hot babe with the retractible ass ticklers in her arms... and its micro-wormhole generating technology that lets it communicate far further distances than simple subspace...
Re:They need better instruments, then they might b (Score:2)
Re:The Paper is here (Score:2)
Huh? the RTGs' radioactive heat source is completely enclosed, the particles it generates do not have enough energy to penetrate the shielding and give up their momentum to the enclosure. Therefore, no net momentum change caused by the decay products, other than the known-to-be-miniscule contribution of individual neutrinos.
Not that it matters anyway, since the decays would happen equally likely in all directions, so even if the particles were released the net effect would be zero.
More ACBS...
Magnetic braking? (Score:2)
But then something that obvious would probably have been looked into. It would be much easier to make a wild guess, if there was a list of effects already looked into and dismissed. (The paper is apparently slashdotted).
Re:Invasion of The Mind Snatchers (Score:2)
Then again, crackpottery is relative, as MOBE2001 demonstrates by calling every other spacetime physicist one.
--
Re:informed content? (Score:2)
--
Re:Invasion of The Mind Snatchers (Score:2)
Looks like he's got multiple Slashdot accounts, too.
--
I have the answer... (Score:2)
Sorry guys, but the strong arm tactics of The Orion Grays and their Intellectual Property Laws have somewhat forced me into silence.
I'll give you a hint though...
...it has something to do with ò[NO CARRIER]
"Everything you know is wrong. (And stupid.)"
Re:Niven readers have understood this for decades (Score:2)
Peter
Re:The Paper is here (Score:3)
Due to the fact that the size of the anomalous acceleration is of order cH, whereH is the Hubble
constant (see Eq. (56)), the Pioneer results have stimulated a number of new physics suggestions.
For example, Rosales and S anchez-Gomez [136] propose that aP is due to a local curvature in
light geodesics in the expanding spacetime universe. They argue that the Pioneer eect represents
a new cosmological Foucault experiment, since the solar system coordinates are not true inertial
coordinates with respect to the expansion of the universe. Therefore, the Pioneers are mimicking
the role that the rotating Earth plays in Foucault's experiment. Therefore, in this picture the
eect is not a \true physical eect" and a coordinate transformation to the co-moving cosmological
coordinate frame would entirely remove the Pioneer eect.
From a similar viewpoint, Guruprasad [137] nds accommodation for the constant term while
trying to explain the annual term as a tidal eect on the physical structure of the spacecraft
itself. In particular, he suggests that the deformations of the physical structure of the spacecraft
(due to external factors such as the eective solar and galactic tidal forces) combined with the
spin of the spacecraft are directly responsible for the detected annual anomaly. Moreover, he
proposes a hypothesis of the planetary Hubble's ow and suggests that Pioneer's anomaly does
not contradict the existing planetary data, but supports his new theory of relativistically elastic
space-time.
stvang [138] further exploits the fact that the gravitational eld of the solar system is
not static with respect to the cosmic expansion. He does note, however, that in order to be
acceptable, any non-standard explanation of the eect should follow from a general theoretical
framework. Even so, stvang still presents quite a radical model. This model advocates the use
of an expanded PPN-framework that includes a direct eect on local scales due to the cosmic
space-time expansion.
Belayev [139] considers a Kaluza-Klein model in 5 dimensions with a time-varying scale factor
for the compactied fth dimension. His comprehensive analysis led to the conclusion that a
variation of the physical constants on a cosmic time scale is responsible for the appearance of the
anomalous acceleration observed in the Pioneer 10/11 tracking data.
Modanese [140] considers the eect of a scale-dependent cosmological term in the gravitational
action. It turns out that, even in the case of a static spherically-symmetric source, the external
solution of his modied gravitational eld equations contains a non-Schwartzschild-like component
that depends on the size of the test particles. He argues that this additional term may be relevant
to the observed anomaly.
A proposal to modify the theory of gravity in order to provide an explanation of the Pioneer
anomaly has also appeared. Capozzielo et al. [141] discuss the possibility of determining the
stability and characteristic geometrical and kinematical properties of galaxies strictly based on a
minimal action whose value is on the order of the Plank constant.
Due to the fact that the size of the anomalous acceleration is of order cH, whereH is the Hubble
constant (see Eq. (56)), the Pioneer results have stimulated a number of new physics suggestions.
For example, Rosales and S anchez-Gomez [136] propose that aP is due to a local curvature in
light geodesics in the expanding spacetime universe. They argue that the Pioneer eect represents
a new cosmological Foucault experiment, since the solar system coordinates are not true inertial
coordinates with respect to the expansion of the universe. Therefore, the Pioneers are mimicking
the role that the rotating Earth plays in Foucault's experiment. Therefore, in this picture the
eect is not a \true physical eect" and a coordinate transformation to the co-moving cosmological
coordinate frame would entirely remove the Pioneer eect.
From a similar viewpoint, Guruprasad [137] nds accommodation for the constant term while
trying to explain the annual term as a tidal eect on the physical structure of the spacecraft
itself. In particular, he suggests that the deformations of the physical structure of the spacecraft
(due to external factors such as the eective solar and galactic tidal forces) combined with the
spin of the spacecraft are directly responsible for the detected annual anomaly. Moreover, he
proposes a hypothesis of the planetary Hubble's ow and suggests that Pioneer's anomaly does
not contradict the existing planetary data, but supports his new theory of relativistically elastic
space-time.
stvang [138] further exploits the fact that the gravitational eld of the solar system is
not static with respect to the cosmic expansion. He does note, however, that in order to be
acceptable, any non-standard explanation of the eect should follow from a general theoretical
framework. Even so, stvang still presents quite a radical model. This model advocates the use
of an expanded PPN-framework that includes a direct eect on local scales due to the cosmic
space-time expansion.
Belayev [139] considers a Kaluza-Klein model in 5 dimensions with a time-varying scale factor
for the compactied fth dimension. His comprehensive analysis led to the conclusion that a
variation of the physical constants on a cosmic time scale is responsible for the appearance of the
anomalous acceleration observed in the Pioneer 10/11 tracking data.
Modanese [140] considers the eect of a scale-dependent cosmological term in the gravitational
action. It turns out that, even in the case of a static spherically-symmetric source, the external
solution of his modied gravitational eld equations contains a non-Schwartzschild-like component
that depends on the size of the test particles. He argues that this additional term may be relevant
to the observed anomaly.
A proposal to modify the theory of gravity in order to provide an explanation of the Pioneer
anomaly has also appeared. Capozzielo et al. [141] discuss the possibility of determining the
stability and characteristic geometrical and kinematical properties of galaxies strictly based on a
minimal action whose value is on the order of the Plank constant.
Re:Informed Comment (Score:5)
The shade theory of gravity (Score:2)
In other words, all objects in the universe emit gravitons, and these exert a force on objects that they weakly itneract with. When you have two objects near each other, they shade each other from the cosmic background graviton flux. As a result, instead of each object having the same force on them from all directions, they now have less force on them from the shaded direction. So the two objects fall towards each other. The force is, coincidentally, proportional to inverse square of distance.
However, a small correction factor is required. The thinning effect of a nearby object is not proportional to the amount of matter in it exactly, because the object shades itself from gravitions. Therefore the correct formula is an integral of an inverse exponential with respect to how deeply the gravitons have passed through the material.
The effect of "self-shading" from gravitons implies that the force law must be corrected so that the gravitional force is smaller than the inverse square of distance for smaller distances. Conversely, as you get further away, the correction is positive relative to the inverse square law.
This theory also helps to explain so-called missing dark matter, and of course it explains the expansion of the universe. It also has strong implications for black holes and the big bang, because it implies that the force of gravity is bounded by the total mass of the universe multiplied by a weak interaction factor. It explains lots of other strange things too.
Could someone pass this on the NASA please?
Re:Just shows how much more there is than we know (Score:2)
Naah. Sounds like you simply lost your ability to let your imagination run free.
Time dilatation? (Score:2)
Well, this was probably the first possibilities they thought of. Anyhow, the phenomenom doesn't have to be caused by a "force".
Science Baffled by extraterrestrial intelligence (Score:2)
My 2 bit informed comment. (Score:2)
A proposal (Score:3)
All these craft are still within the heliopause and will be so for a long time. They're moving outward faster than the solar wind, which means they're flying into it. The vacuum of space is only mostly a vacuum, remember, so the combined impacts of many little atoms will add up over time. The Pioneer craft, in particular, have been out there 20+ years, so the culmulative effects have had time to add up, and these would tend to slow the crafts over time. This effect is not negligible, or solar sails wouldn't work.
Also, as probably a lesser effect, there's all the virtual particles that are springing up in front of the craft and getting run into before they can meet their natural antipartners. These also will register as mass impacts and tend to slow the vehicles.
The first cause in particular will only get worse when the first craft hits the heliopause. At that point, it will no longer be plowing along with, but faster, than our Sun's wind, but head on into new solar winds. I wonder how much more difficult this makes it to come up with enough energy for eventual real interstellar travel.
Just a late night thought or two... but it doesn't seem unreasonable.
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Re:Just shows how much more there is than we know (Score:5)
I'm not sure what planet you're on because you seem to be trying to write an anti-science diatribe and yet much of what you say is no different from the view of a scientist.
--Re:Another Possibility (Score:2)
Sounds close.
My guess was to resolve two questions with this deviated course observation.
If the course deviations get large enough they could point to the missing matter (assuming it is distributed inhomogeneously), if that is in fact, the cause of it all.
Far from being an amateur astronomer, I'm still aspiring to achieve full-fledged diletante status.
Re:Of course NASA don't understand gravity (Score:2)
How is it that a (ghasp) lone scientist with no resources can bullseye planetary magnetic fields before the fact, but NASA (besides many other large and well-equipped organisations) are several orders of magnitude wide of the mark?
You can ignore these links they are creationist psuedo science.
The map is not the territory (Score:2)
Re:The Paper is here (Score:2)
Funny, they didn't include my first thought on what might be causing it: (i) our understanding of the heleopause is incorrect.
It may be that the heleosheath is not a hard boundary, but rather has a mix of both solar winds and interstellar gasses for a much wider region than is presently thought. In other words, it could be that there is no true heleopause at all. If that was the case, our little space probes could have been heading "upwind" against largely stagnant gasses for some time now, slowing them.
Of course I have absolutely no evidence for this, but it is a missing hypothesis.
Re:As every fan of McElwaine knows... (Score:2)
assumptions about gravity (Score:4)
Re:Informed Comment (Score:2)
That's Right.
All your gravitational forces are belong to us!
Re:Some possibilities... (Score:3)
(2) Not likely. Small things can theoretical deflect the probe. However you run into two showstoppers (i) things are too small to make any difference (ii) the things will deflect the probe, averaged out, in an "isotropic" way (what this means is that, on average, there will be no net deflection).
(3) Possible. But this uneven distribution will be detected long before. It's discussed in the paper that I listed in another post here. The punchline is that such things will also cost deflection of the planets, and we don't see that.
Hope this helps.
The Paper is here (Score:5)
Possibles are
(a) Heat Ejection (b) Gas Leak (c) Clock Drift (d) Anomalous objects (pretty dead, despite BBC giving prominence) (e) modifications to gravity (f) solar radiation pressure (g) systematics of observations (h) antenna radiation pressure
Let the armchair speculation begin. (But remember to read the paper to check your answers!) Have Fun!
You forgot about cancer. (Score:2)
Re:They need better instruments, then they might b (Score:2)
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Well maybe... (Score:2)
Shape of the universe (Score:5)
While this news report is very likely just a measurement error, we must be reminded that the last time we discovered an error in a celestial body's trajectory we reinvented the notion of the universe.
One of the big open questions of the day is: What is the shape of the universe? Euclidean, hyperbolic, a torus--we aren't sure. It is thought that each of these geometries would profoundly affect an object moving across the universe in a different way. These NASA probes could in a sense be the moving laboratory that we need to understand what exactly our universe looks like.
Robert
http://wso.williams.edu/~rmcgehee [williams.edu]
Re:They need better instruments, then they might b (Score:2)
Voyager is more advanced than anything that NASA has produced lately. Pathfinder was a joke, not to talk about the failures that followed. It is doubtful whether with "faster, better, cheaper" Goldin in power, NASA would manage to build another Voyager, let alone a more advanced probe. I'm happy that they keep listening to it at all.
But if we get something decent built in the next decades, we might as well send a probe to 550 AU and use the sun as a gravitational lens for SETI. Talk about alien TV stations ..
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Re:Shape of the universe (Score:2)
I understand measurement error has been pretty much ruled out as well as another planet.
By the way, this news report first appeared in The Economist over a year ago.
Not the first time it has happened either. The Economist was the first non-technical journal to talk about the Internet in a general context, abck in 1991-1992.
Old News (Score:2)
Well, I guess the final JPL report is newsworthy.
Note: I don't frequent the online Bible sites, but I knew I had heard this years ago and the referenced site turned up near the top of my Google search!
BBC knows it all (Score:2)
Re:Another Possibility (Score:2)
I have always been of the opinion that if alien life can't find a better way to communicate than anal probing -- and now maybe monkeying ever so slightly with the course of our abandoned spacecraft -- then they are not worth talking to. Worth bombing, maybe.
Damn aliens.
Re:Just shows how much more there is than we know (Score:2)
someone mod this up.
The point about what-if theories (Score:3)
And that was one of the most important creative leaps that led to quantum mechanics that gave us electronics, computing, and hence Slashdot. Almost as if my miracle, the equations worked! After some eighty years, we still don't admit that particles are waves, but it is one heck of a model. In principle, physics is not about what is real, it is about models of the nature. (Insert your favourite definition of reality from the Matrix here.) Physics does a lot of things purely systematically, but new theories like wave mechanics require those what-if ideas that may seem stupid at the first glance. The validity of a model can usually be tested by experiment, and if it fails then we can be certain that the idea was 'stupid' indeed. We can only let Nature judge which models are better.
I agree that ultimately physics should be about particles - or rather whatever the fundamental objects turn out to be (strings? a very elegant _model_ but maybe nothing more). The problem is, before we get there, we want to be able to model the larger scales as well. We can quite safely model the largest scale of the universe without worrying about the underlying forces between individual particles. Maybe that model (i.e. General Relativity for now) isn't absolutely accurate, but it's better than having to wait for a theory of everything - which BTW may never come up.
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Gravity is perhaps the least understood force (Score:3)
The strong force is carried by particles called "gluons" while the weak force is carried by "weak bosons". The electromagnetic force is carried by "photons". These have been detected in particle accelerators. Scientists have a name for the carrier particle of gravity - "graviton", but it has never been detected - yet.
The strong and weak force have a relatively (no pun intended) limited range. The strong force has a range of only about 1x10^-15 meters. On the other hand, gravity and the electromagnetic force have infinite ranges. Perhaps we're wrong about the gravity force, considering we don't even have a carrier particle. Maybe its strength isn't an inverse squared relationship for infinitely long distances - or it's simply an approximation.
Too bad I don't know nearly enough about experiments testing the gravitational constant and how well we've applied it to extrasolar objects.
Re:old story (Score:2)
Informed comment? (Score:3)
You'll see lots of speculation by people who have no idea what they're talking about, but at least that won't get modded up. You'll also see lots of speculation by people who have a very slight idea of what they're talking about, and even though that speculation is little better, it will get modded up by other people who have a slight idea of what they're talking about, because it sounds plausible.
Maybe a legitimate space scientist or two will post with something that might actually be useful. Maybe--possibly--that will get modded up. More likely it won't, because it will be over most people's heads, or because he came too late to the conversation (say, two days from now) when no one's going to use mod points on the story.
Assuming your characterization of the BBC story is accurate (/.ed, can't get to it right now), and assuming that the BBC story itself is accurate--both of which are nontrivial assumptions--why wouldn't the quoted "NASA scientists" be the informed comment you're looking for? Is anyone here going to give you a better answer than the "we don't know" you got from the NASA scientists?
(Don't mind my ranting, I'm just in an anti-/. mood today.)
Re:Another Possibility (Score:3)
here's a reason.... (Score:2)
-Daniel S. Goldin, Head of NASA, two weeks later
Re:They need better instruments, then they might b (Score:2)
Based on what criteria? The processing power of its computer? The sophistication, compactness and sensitivity of its instruments? The Voyagers were marvels of 1970s technology, but current probes can definitely do more for less.
The difference between Voyager and current proposals is that Voyager cost billions of dollars, while most probes nowadays come in at under $400 million. Voyager had about a dozen instuments, most probes now have at most five or six. Voyager was exploring areas of the solar system that we had never been to before, so everything was new, and major discoveries were dropping into our laps. Mars still has surprises in store, but they are more subtle than volcanos on Io, or braided rings around Saturn.
There is one last superprobe still to go; Cassini [nasa.gov] is the biggest probe ever launched, with a dozen instruments. It also cost over three billion dollars. We will not see its like again.
Creation, QED! (Score:2)
They need better instruments, then they might be (Score:2)
I would not mind seeing a mission equiped so they could determine what really is out there. In other words, ditch the hardware needed for planetary observations, use the slingshot effects of gravity and get a probe out there pronto.
It would probably be a better use to understand what goes on out there than visit the disney planet.
As every fan of McElwaine knows... (Score:2)
This IMPORANT INFORMATION should be DISSEMINATED etc etc...
With apologies to Robert McElwaine, and everyone else.
OK,
- B
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Re:As every fan of McElwaine knows... (Score:2)
And besides, McElwaine is still out there, just with a smaller readership.
OK,
- B
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Maybe it's "The" Force (Score:3)
Probe:[ continues course ]
Jedi:(under breath) "Oops."
[ Jedi waves hand in front of probe ]
Jedi:"You will alter your course."
[ back on earth... ]
BBC News:"Mystery force tugs distant probes" [bbc.co.uk]
Ewige Blumenkraft!
Re:Informed comment? (Score:2)
> post with something that might actually be useful.
Curiously enough, that was exactly what I was hoping . Now that I've finally lain the karma-whore ghost, I'm reading at -1, and, well, it's embarrassing to admit but I've been laughing my arse off.
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Re:Interstellar Medium Density? (Score:2)
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Re:The Paper is here (Score:2)
As an example of the sort of phenomena which can add up to a noticeable effect over long periods of time, check out the results from NEAR Shoemaker probve to Eros (you rmemeber, probe that orbited & finally landed on asteroid Eros.) ON eof severla unexpected results is that there are disproportionately fewer small impact craters than would be expected, given the number (density) of larger ones. One possible explanation for this is is that small (c. 1cm diameter) orbiting rocks may be preferentially expelled from the inner solar system, due to the fact that as they spin, the side that has just moved from sunlit to dark side re-radiates some of the energy it's absorbed from the sun. This leads (in some obscure but very clever theory which I can't find a link for right this moment) to these objects drifting slowly away from the sun. This doesn't affect larger objects because their ratio of surface area to volume is different...
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Re:The Paper is here (Score:4)
Sod's law suggests that it's 99% likely to be one of (a|b|c|d|g|h). However, astronomers and physicists are generally rather good at methodically excluding likely explanations, starting with the least unlikely, until all that's left, however unlikely,..
We know that, at some level, the standard model is inconsistent - quantum physics and relativity are mutually incompatible. One tantalising observation for which there's no generally accepted explanation is that gravity is many, many orders of magnitude less powerful than the other fundamental forces.
I'd love ot believe that this phenomena, which has been bobbing around for a few years now, is a pointer to some Theory of Everything. But, after 25 years in space, the tiniest force acting on the probes which is not accounted for, can stack up to an observable difference of position from prediction.
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Re:Another Possibility (Score:2)
About the only theroy I've got is maybe there is a dark "brown dwarf" star companion of Sol orbiting out there. Could that explain it?
Don't know, but I suspect that small mass pseudo-stars like Brown Dwarfs will be found to be among the most common objects in the universe (as it's known that the sim, low mass, long lived Red Dwarf stars are by FAR the most common stars).
A brown dwarf in the Oort Cloud may be dark enough to be obscured by the comet-like matter there, yet have enough influence to affect the outer solar system (like sending the odd new comet towards the Sun every now and then).
But then, I'm only a curious amateur in Astronomy
Re:Could this be the "missing mass" explanation? (Score:2)
Just in my own lifetime, the picture of our Solar System has changed drastically, with the information the Pioneers and the Voyagers returned and still return (Pioneer 10 was launched close to the very day I was born!)
In fact, with the recent confirmation of the existance of other solar systems with planets, our theroies on what is "normal" for solar systems are already in question...
Is there any doubt that those four little spacecraft, of our WHOLE space program, delivered the MOST bang for the buck? And that we should be sending more advanced versions of them out?
Planets unaffected? (Score:2)
"It would be apparent in the orbits of the planets around the Sun - which it is not".
Now, someone please correct me if I have this wrong, but don't estimates of the physical properties' of planets *derive* from the behavior of those planets under the assumptions of our best current understanding of gravity?
So, how can we claim that the planets do not seem affected by this "mystery force"? If we use the orbital radius and centripetal acceleration of a planet to calculate its mass, we can't then use that calculated mass to "prove" that the THEORY of gravitational attraction as we know it applies perfectly.
Re:Invasion of The Mind Snatchers (Score:2)
Thanks to the moderators who modded me up.
Is it the probe or is it us? (Score:2)
Perhaps this observed acceleration is actually us "decelerating". Could our close proximity to a large source of gravitation (the sun) lead to such an observation?
We need to, er, Think Different(TM) about stuff like this.
Sub-surface Global Conspiracy (Score:2)
God bless those Albino Ninjas...
Well said (Score:2)
- John Keats
I have many times had this aesthetic argument with math and physics students. It took a long time, but we eventually came to the following consensus on the aesthetics of science:
Scientific fact, in and of itself, is as completely devoid of artistic interest, as any fact is. The mere cold fact of the way in which paint was arranged on a piece of canvas to create the Mona Lisa is devoid of aesthetic value. Only a human interpretation of the meaning of this arrangement of paints can yield aesthetic worth. Therefore, for example, while the theory of relativity is, in and of itself, without merit as art, by an interpretation of its implications to humanity, it can gain meaning. The exciting thing about it is that we DON'T understand it completely. We can make all manner of wild romantic ponderings on its meaning with regard to light-speed travel and all sorts of fantasies. It's only because we don't understand it that we can make these ponderings, however. If we had a complete and thorough "scientific" knowledge of its (or "the theory of everything"'s) meaning and nature, light-speed travel or time travel, for that matter, would be either 1) recognised as impossible or 2) as matter-of-fact as travel at greater than the speed of sound.
The only reason science is interesting is because it entails mystery (if it didn't, there would be nothing more to investigate) and uncovers new topics for us to consider in wonder. Unfortunately, while it does this, it disproves the things that we used to wonder at (like a 6,000-year-old earth and Thor weilding his thunderbolts from the clouds). The end result is that the only things that we have to wonder at any more are so incredibly abstruse that only scientists can explore them. The common man used to be able, as the above poster noted, to look up into the stars and wonder even what they might be. Unfortunately, these wonders within the reach of the common man have already been explained. The worm holes, dark matter and Uncertainty which remain the wonders of today are somewhat beyond his grasp.
I think this is all summed up in a quote from David Hume:
The anatomist is useful to the painter"
The scientist investigating the human body and the artist who depicts it work hand in hand to create the final product. This is perhaps a consensus to be made between scientific and artistic aesthetics.