There’s a lot more to discover about gravity besides knowing that it makes apples fall on your head. That’s why NASA has launched the LAGEOS and Gravity Probe B satellites into orbit around the Earth, profiled in today’s other SciScoop article, to look for one hypothesized gravitational effect called frame dragging that’s never been seen before.
Yet even while these nearby satellites are breaking new ground in discovering the basics of space and time, there are other mysteries about gravity that are being uncovered by more distant NASA probes. Robert Britt of Space.com recently wrote an article on this so-called “pioneer anomaly” as part of his excellent continuing series on The Greatest Myths, Hoaxes & Mysteries in Astronomy and Space Science. A few paragraphs from his most recent article are summarized below.
“More than a decade ago a researcher noticed something funny about two Pioneer spacecraft that were streaming toward the edge of the solar system. They weren’t where they should have been. Something was holding the probes back, according to calculations of their paths, speed and how the gravity of all the objects in the solar system — and even a tiny push provided by sunlight — ought to act on them. Pioneer 10 and 11 launched in 1972 and 1973. Today each is several billion miles away, heading in opposite directions out of the solar system. The discrepancy caused by the anomaly amounts to about 248,500 miles (400,000 kilometers), or roughly the distance between Earth and the Moon. That’s how much farther the probes should have traveled in their 34 years, if our understanding of gravity is correct.
Which leaves open staggering possibilities that would force wholesale reprinting of all physics books:
- Invisible dark matter is tugging at the probes
- Other dimensions create small forces we don’t understand
- Gravity works differently than we think”
Check out Robert Britt’s Space.com main article on the Pioneer Anomaly for more details; there’s something funny going on out there.
You know, a while back I remember that some group of scientist discovered that the universe did not seem to expand as gravity would predict it, and as one very possible explanation they stated that dark matter may be at work.
I find it interesting that Dark Matter alegedly affects objects with a stronger force at greater distances. I remember though, that Dark matter was thought to repel objects, not attract them.
I believe that if you do a search on google you can find that explanation somewhere.
The only way I see Dark Matter working is that if we have some very distant object repel on the two Pioneers. But shouldn’t we then expirience this force here on Earth?
And here I will go on a limb:
I think that one other possible explanation for this phenomenon is the rotation of the Sun. The Sun haa much greater mass than any other object in our solar system. It’s rotation will, as I remember reading somewhere, curve space around itself. In other words, not only does the mass "push" a dent in your standart space graph generally expresed by the formula
z= Msun/SquareRoot(x^2+y^2)
but it also twists the gravity lines around itself. I am going to try and post a picture to clerefy this idea.
To continue, the distance travelled then would have been as predicted, excpet that the object actually traveled on a curved line, and is not as far away, if you make a straight line from the sun.
I will continue on this idea as soon as I get my picture.
Milcho.
P.S.: Excuse my missplelling, becasue this was written at a rather late hour.
I have just finished doing some research on this “Pioneer 10 &11” anomaly in their position as predicted by General Relativity.
The situation reminds me of the anomaly observed in Mercury’s orbit which wasn’t predicted by Newtons theory of gravity, leading to the prediction of another planet “Vulcan” which was tugging on Mercury. Of course there was no Vulcan and once Relativity came along it actually predicted the effect observed. Ten points for Einstein and the rest, as they say, is History.
Given the persistence of this anomaly, 10 years, multiple craft, I think we are seeing (finally) something not predicted by Einstein. Someone is going to come up with a theory eclipsing Relativity which will actually predict these and other anomalies. Then I believe we will see Dark Matter and perhaps Dark Energy disappear.
Its been a long time coming, String theory has little hope of being testable, the true theory of Everything should be able to explain these anomalies and hopefully more!
Rohan Lorange
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