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Frame Dragging by Earth Reconfirmed
smooth wombat writes "After 11 years of watching the movements of two Earth-orbiting satellites, researchers found each is dragged by about 6 feet (2 meters) every year because the very fabric of space is twisted by our whirling world.
The results, announced today, are much more precise than preliminary findings published by the same group in the late 1990s.
The researchers say their result is 99 percent of the predicted drag, with an error of up to 10 percent. The details are reported in the Oct. 21 issue of the journal Nature."
Hmmm... I read this earlier because CNN jumped on it, but there are questions (noted in the Nature article) about its actual accuracy. There's some concern that the original gravity field maps that this method used weren't accurate enough.
This is a good step forward, but I think until we call the frame dragging prediction confirmed we should wait to see what Gravity Probe B comes up with.
Alito: A vote for Alito is a punch in the eye to put that bitch back in her place!
-HJ
You're thinking of NASA's Gravity Probe B. That one isn't finished yet.
Actually, the article could do better to explain the difference between the law of gravity (which is the mathematical formula which describes the attraction between two masses) and the theory of gravity, which attempts to explain how or why two masses attract each other exactly that way.
Ideology: A tool used primarily to avoid the bother of thinking.
This idea of this drag was originally proposed by Einstein. Almost fifty years ago, the idea of how to experimentally verify this effect was proposed; however, it required the launch of a very accurate gyroscope. That gyroscope, which is the center-piece of the longest running NASA project ever, was just recently launched into space. More info about it (Gravity Probe-B) and a good description of this drag can be found at http://einstein.stanford.edu. Yes, the article is describing a different project than GP-B; however, it references the skeptism that the folks at GP-B have expressed at this latest experiment, and the GP-B folks are considered the experts in the field. Check out their site, it's fascinating.
No. Scientific theories don't get promoted to laws. Laws are observations of things that appear to hold true. For example, the law of gravity ("what goes up, must come down"), Snell's Law, Ohm's Law, the Law of conservation of Mass/Energy, the Laws of Thermodynamics, etc. A theory is an *explanation* that models some observed phenomena and which has the power to predict other phenomena. Theories are either falsified (i.e. proven wrong), or are confirmed (i.e. shown to be consistent with some new observation.) Theories are never proven true; rather, they are simply confirmed to a greater and greater degree. No matter how well a theory is confirmed, it can always be falsified by a new experiment testing some as-yet-untested prediction. In this case, the theory is either revised to account for the new observation, or it is simply discarded.
For those of you like me who didn't have a clue what this article is about check out the Wikipedia entry for frame dragging.
No, this is different, Gravity Probe B is a separate project, this was an Italian research group who used freely avaliable data from the past 11 years of the two LAGEOS satelites, who's orbital paths have been monitored for that time. Space.com has a good summary, and so does New Scientist
In the future, we will all be very smart or very stupid.
Newton's laws have not been proved, they are just very likely. And there are some problems with them. So why not extend this naming to relativity?
I could say "My theory includes everything in General Relativity, except for a small sphere four miles wide in the center of Andromeda, where light travels twice as fast."
Then while you have a theory that has not been disproved, Ockhams Razor advises us to use the simplest one that explains all the data, and that's not yours.
Yes, this makes truly proving anything in the physical world basically impossible.
Which is why it is not a good idea for us to require theories to be "proven" before becoming "natural laws". We call a proven "theory" a "theorem".
This post written under Gentoo-linux with an SCO IP license.
You obviously don't understand margin of error. The large error suggests imprecise measurement, the central limit suggests that the end value will in fact be close to the predicted. 99% +/- 10% is more promising with regards to the theory than 99% +/- 0.01% would be.
Statistics lesson.
Margin of error is not a bound within which any result is equally likely. Depending on the distribution, it can be anywhere from equal likelihood (uniform distribution, which is extremely rare in natural processes) to single point (in which case the MOE is obviously zero, and the result is definitive.) For example, most things with a binary outcome (yes or no, 1 or 0, etc) follow what's known as the binomial distribution. If the probability of either result is equal, the binomial pattern is equivalent to the normal (Gaussian) distribution, which looks like a bell, and is produced by many processes, especially processes involved in noise and measurement error.
Now, depending on the expected distribution this changes, but for a normal distribution the likelihood is probably 95% that the actual value is within that +/-10% (assuming they're using the typical definition of 2 sigma for margin of error) - but it's around 65% likely that the result is within +/- 5%, and the most likely single result is in fact 99% - not 99% likely, but the maximum likelihood points to 99%.
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