Slashdot Mirror
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."
It'd just be great if after all this time we actually find out something like it's not possible to leave the solar system without some sort of extreme propulsion system.
It could be an example of gravitiontational rippling.
a very large gravity well may have a ripple that exists some distance from the center of the gravity well. The sun's gravity well is big enough for us to notice this while the sun and other planets we did not notice it. we MIGHT be able to notice something if we look at the data as these probes appriached and passed juipter.
Do not look at laser with remaining good eye.
From TFA They had been tracking the probes using the giant dishes of Nasa's Deep Space Network.
This doesn't quite quench my thirst for information: does this mean the probes are still sending radio waves/signals, or just irradiating passively?
Sigged!
im not scientist, and surely these articles are written for the layman, but all of the articles i've read say "something more than the sun's gravity is pulling at the probes"
wouldn't the planets, especially jupiter, and saturn, and ALL of the misc tiny asteroids in the various belts, exert a pull on the probes as well? some sort of combined solar system gravitational force since the probes are well beyond the last planet?
doesn't seem that complicated to me, but im definately coming at it from a relatively uneducated perspective then who's saying something's wrong in the first place.
I remember reading a quite striking short story about a crystal shell surrounding every solar system and it can only be broken from inside. It works like a semi-permeable interface, preventing aliens coming /communicating inside. A civilization will only manage to get outside of the shell by breaking the "egg". I can't remember the writer of the story nor the name but I think I read it on either Asimov or Analog in the last couple of years. Can anyone recall this story and remind me of its writer please?
According to this paper, it could be drag from dust in the outer solar system.
Um, I'm way out of my area of expertice here, so forgive me if this is utter drivel.
The probes are basically big lumps of metal moving at high speed through space.
How much do we know about the magnetic fields in deep space?
Could this be some fairly boring electromagnetic effect?
Quidquid Latine dictum sit, altum videtur (anything said in Latin sounds important)
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.
As a sci fi reader, I of course hope that light speed is a breakable barrier.
As someone who studied physics, I'm not too hopeful. The speed limit isn't the result of a few shaky theories, but rather a pretty deeply engrained part of our understanding. If it turns out not to be true, then most of the physics that has been done for the past 150 years is flat out wrong. It would be like discovering that DNA isn't where the genetic code is held, as disasterous, and at this point in our study, as unlikely.
In Capitalist America, bank robs you!
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
speaking of gravitational rippling, maybe you can answer a question for me...
Special relativity says there isn't any particular speed that is at rest, right? Speeds are always relative, right?
But gravitational rippling leaks energy until the object is at rest, right? So there must be a rest state of zero speed.. so there must be an absolute zero speed?
I heard other things.
If you read TFA, you'll notice that they are talking about a force acting equally on *both* probes.
Claims that this is a new effect are a bit too early, though.
Occam's razor doesn't mean that scientists should stop investigating because there _may be_ a simple explanation. If there are interesting, unexplained things, one has to go down and calculate every traditional force(/space time curvature) which may act on the spacecraft; numerical simulations of the radiation pressure of the RTGs, taking the geometry of the space craft into account. Other external electromagnetic forces. Etc.pp.
Then, there will probably be a traditional explanation of the effect. If not send some probes out too further investigate the effect. After all, experimental physics is not only about testing the theory's POV, it is also about exploring the world and finding new effects.
You can have wrong calculations by theoreticians even in such fields where there is a fundamental theory capable of explaining everything. (This includes nearly every field of physics today - except nuclear/particle physics and astrophysics).
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
Gravitation rippling only happens to accelerating objects, so it does not violate relativity. It works the same way as brensstrahlung (ie., breaking radiation). It is believed that accelerating objects emit gravitons (gravity particles) in the same way accelerating charges emit photons (electromagnetic particles). The braking is relative to the object causing the acceleration.
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
MOND
/.
Well, it's what some physicists may be thinking, anyway. I suspect that the Guardian article is meaning to hint at this, as well. For those who don't know, MOND is a modification of standard Newtonian Dynamics that has to do with very small accelerations. I'd actually really, really like to see a MONDian calcuation of what the forces should be on those probes and see if it matches their current paths.
Wow. I think this is the second time I've advocated MOND (a theory which I just barely consider reasonable, and no where near verified) on
I couldn't tell if you were experimenting with poor-man's cryogenics or looking for the orange sherbet.
Personally? In German the field of engineering is called "Ingenieurwissenschaften", i.e. engineer sciences.
The Tao of math: The numbers you can count are not the real numbers.
The casimir effect cannot exist, as I understand it, on large scales like that. Its a force that results from the interesting effects of bringing two conductive surfaces so close to one another that only certain wavelengths of virtual parties can exist between the plates, whereas all wavelengths exist on the other sides of the plates. As a result, there is vacuum pressure pushing the plates together.
Its worth mentioning that yes, this could be used to extract energy from the vacuum, although no one has figured out (a) how to do this on a large enough scale to be useful and (b) whether it would take more energy to position the plates than you could extract (see below).
Logically, the energy to seperate the plates from one another should equal the energy gained by their collapse together due to vacuum pressure, so that should mean this is no net-gain.
"Stumble before you crawl"
No, the singularity has finite mass. It has infinite density, but that's because it has zero volume.
Of course the black hole has not zero volume, because the term "size of the black hole" doesn't refer to the singularity (which might not actually exist; you can't just go into a black hole, look if there's a singularity inside, and come out again), but to the event horizon (which is the border of the region from where you cannot escape, nor can anything else, including light).
The Tao of math: The numbers you can count are not the real numbers.
Actually, you're mistaken. It has infinite density not mass: theoretically a simple singularity has zero volume, thus its density is whatever its mass M is, divided by zero. That results in an infinity (and is why, actually, its called a singularity, a math term).
Moreover, there are no simple singularities, even in theoretical GR. According to Kerr, it can be demonstrated that all black holes [if they exist] have a "ring singularity" at their core, not a point singularity. The reason is simple: black holes rotate. If you have a point singularity w/ zero volume, there is no means to differentiate a rotating body versus a non-rotating body. Mathematically and conceptually, Kerr demonstrated that this means that singularities actually distort into a zero-thickness torus called a ring singularity (with its plane lying on the plane of rotation of the black hole). Inside the ring, it seems, there would be a tear. This was even realized by Einstein, and is the birth of the concept of an Einstein-Rosen bridge (and the subsequent dialog about wormholes/white holes).
"Stumble before you crawl"
Couldn't it be continuously hitting against clouds of dust?
How close are these probes relative to the Oort cloud? I would think that what we are witnessing is that the probes lack the velocity to escape and will eventually become part of the Oort cloud.
"I bow to no man" - Riddick
From the script of the first episode: From this it can be deduced that the maximum warp that the new engine was designed for was warp 5, but they were going to be testing out warp 4.5 for the first time.
If you use warp 4.5 = 91.125*c for 4 days you get 0.998 light-years. This is so close to a light-year (possibly rounding issues) that the writer who came up with 4 days probably forgot to multiply by the number of light-years to Kronos.
Even if you use warp 5, you get 1.37 light-years. Considering that Alpha Centauri is 4.4 light-years from Earth, the 4 days at warp 5 idea still sounds absurd.
Let's go Hurricanes!!! 2006 Stanley Cup Champions!!!
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.
You say the writer screwed up the calculation, I say he conveniently forgot to do the math and worked in 4 days based on his storyboard timeline. Sure they could imply dead days but that makes the action seem much more spread out which can kill the pacing and energy of a show.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
gaining mass by gathering dust?
bj
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.