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."

Comments

networks

[OwlofCreamCheese]

derr... my brain thought "what? frame dragging? story about networks or something?"

Re:networks

[databyss]

I thought it had to do with some new rendering techinique in HL2.... then i realized it was just boring old space-time stuff...

Ouch...

[tetranitrate]

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

The researchers say their result is 99 percent of the predicted drag, with an error of up to 10 percent

I think my head just exploded

Why, this explains why....

[Tablizer]

....I can't find the @!#% TV remote. Time to diet, I guess.

GR lives on and on

[metlin]

I was under the impression that there has been experimental evidence for the existence of Spin Distortions in Lense Thirring effect?

This would mean that inward spiralling matter observed near black-hole like phenomenon were indeed valid physically.

But as the Nature article points out, the accuracy of Ciufolini's work not yet certain, since the value is not absolutely the same as that predicted by relativity (only 99%, with an error of upto 10%). And anyway, the last major prediction of GR -- gravity waves -- is not yet done.

So until then, three cheers for experimental physics!

Re:GR lives on and on

[Kiryat Malachi]

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%.

Don't Get TOO Excited

[the_mad_poster]

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.

Re:Don't Get TOO Excited

[the_mad_poster]

Frame dragging is the explanation for observed inconsistencies in the swirling gas/dust clouds surrounding massive black holes, but I don't know that this portion of the theory has ever been confirmed via experiment.

Re:Don't Get TOO Excited

[Rob Carr]

It's just that it is easier to observer the phenomenon around blackholes owing to their massive nature.

The problem with the black hole observations is that a number of guestimates need to be made. The guestimates are probably valid, but there's enough wiggle room that it's hard to say the effect is really there.

The gravity maps that were used for this latest release are far more accurate than previous attempts to do this with the 11 years of data, and it seems to have confirmed that frame dragging does occur as per relativity.

The Gravity B experiment will be one more proof of frame dragging - although no one really expected frame dragging to be disproved. There's too many other things about General Relativity that have been confirmed.

Somewhere, General Relativity must break down so that it can match up with wherever Quantum Mechanics breaks down, permitting the two theories to be joined in some coherent fashion. But there's no way that frame dragging could be the place where General Relativity gives out. It's an experiment that needed to be done. It's dotting the i and crossing the t. But it's not worth much. That's the real debate. Should all the money have been spent on Gravity Probe B to prove something everyone accepts, or should other ways (like digging up 11 years of satellite data) have been used and the money spent on something that might actually give a bang for the buck?

Re:Isn't that...

[Anonymous Coward]

Yes, the project is called Gravity Probe B, launched in mid-April 2004.

-HJ

Comment removed

[account_deleted]

Comment removed based on user account deletion

No, you're wrong.

[Anonymous Coward]

You're thinking of NASA's Gravity Probe B. That one isn't finished yet.

Some Equations

[nate nice]

Tysons Equation explains this:

ch/(c - ke^n)

Where c is speed of light, of course, h is a coefficient representing the fabric and this is a quotient where k is a coefficient to the constant e (~ 2.7) and raised to n which is a variable for mass or changing objects in space.

Sanders developed a corollary for this saying:

f-r/e^d

where f is the temperature in space in farenheight and r is the change, divided by e, again, to the d, which is similar to n, but loses its delta value.

It's a lot to grasp if you don't know physics well, but what they say is that objects do indeed get entangled in the fabric of space time and move, due to gravity. Neat stuff...really. Hehehe.

Re:Some Equations

[synaptik]

Stupids mods... this should be funny, not informative. "Chicken" ... "Sanders" ... "Fred" ... it's obviously a joke.

A real 'clucker' of a joke, in fact.

Not posting anonymous, so that I can receive the karmic flogging I deserve for making this meta-comment.

Re:Isn't it time soon...

[mjm1231]

No. This is a common misconception, but theories do not become laws by collecting evidence in their favor. (Otherwise evolution would have been elevated from theory to law long ago). See this Wikipedia article.

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.

More Info on twisting Space

[alaivfc]

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.

Perhaps

[bleckywelcky]

From the CNN article:

"Ciufolini's team analyzed millions of laser signals bounced off two satellites, called LAGEOS and LAGEOS 2. Both are highly reflective spheres not designed to do any work of their own. They look like 2-foot-diameter (0.6m) golf balls and contain no batteries or electronics."

Space Balls?

i don't understand this article

[Trepidity]

My framerate has been dragging too but I don't see the relevance of satellites to this issue. I've got cablemodem so satellite internet latency cannot be the problem.

A Brief Explanation

[Pugio]

For those who aren't familiar with all of this: (I know they included it in the article but here's my own explanation.)

Basically (acc. to the theory of relativity), gravity is not really a pull from one object to the other. What it is is a distortion in the fabric of space-time. What does this mean? Well think about a sheet stretched out very flat. On this sheeta are a number of very light objects. Now think of a lead weight placed in the center of the sheet. The sheet will bend into an inverted cone shape and all the items will slide towards the weight. Ta Da! Gravity!

Gravity is an extremely pervasive force. While it is the weakest of the defined forces, it permeates every area of our universe and, overall, has the largest impact. It is even powerfull enough to warp light. Again, just think of light as travelling along the surface of the sheet, the depression in the middle will warp the ligh as it travels.

What this article is describing is a secondary gravitational effect. Now, not only does this lead weight cause things to fall towards it, but if the lead weight was spinning, it will create another path/pull of gravity. In the sheet example. think of the lead weight as shaped like a corkscrew. Now imagine what would happen if you started turning that corkscrew. Not only would the sheet be weighed down in that area but it would also become wrapped around the corkscrew, causing further twisting in the fabric of the sheet. This is the effect that is currently trying to be proved.

Black holes are essentially very very very heavy weights. They create an extremely big "depression" in the fabric of the sheet. Many black holes also spin on their axis, much as the earth does. This spinning again distorts the sheet but, given how heavy the black hole is, it causes very large distortions.

This is all predicted by the theory of relativity. For this theory to be considered valid, it must make certain predictions that can be (eventually) proven. If this experiment is, in fact, true then this is yet another proof that relativity is the real deal. And there you have it.

Actually, now that I think about it. This pattern that they describe with the black hole looks exactly like a spiral galaxy (ie. the milky way) - with large "waves" coming out on all sides. It has been theorized that there is an enormous black hole at the center of the galaxy - could this be evidence of it?

Re:A Brief Explanation

[808140]

Your question is a good one, but it has no answer. I'd like to explain why. It's a matter of philosophy.

You see, science (especially in popular consciousness) is seen as the discipline which endeavors to answer the question "why?" with respect to various observable phenomena. These questions have been at the center of human thought for well, ever. We created religion in its various forms to answer this very class of questions.

With the advent of science, it seemed as though we finally had a way to truly answer these questions, but unfortunately this stems from a fundamental misunderstanding of what science is. Science does not try to answer nor can it answer the why. The why has no answer.

Let me explain. Science (and specifically the scientific method) is designed to determine, through experiment and falsifiability of hypothesis, the way the world behaves and to model its behaviour. Because these theories often have far reaching consequences, laymen (and even scientists, unfortunately) often make the mistake of thinking that their theories explain the why. But they do not; they simply explain the how.

Let's explore this a bit. Newton's law of gravity did not explain why gravity exists. Why two bodies fall together is anyone's guess -- why, as a question, demands a reason. There may very well be a reason that two bodies fall together -- a popularly believed one is that some supernatural being designed it that way -- but physics does not, indeed, cannot, conjure up a reason by simply observing and modeling the way those two objects fall together.

An example of this in more human terms: suppose you have a batty friend, and everytime you say foo, he says bar, like clockwork. You would quickly observe this and would, in your mind, be able to construct a hypothesis based on this behaviour -- when the subject hears foo, he says bar. And you could construct a series of experiments that test this hypothesis -- perhaps you would find that in the presence of blondes, he utters baz instead. This knowledge would allow you to predict his behaviour in certain situations, but it would say nothing whatsoever about his reasons for it. Nor could any amount of observation ever explain the reasons.

Now, in physics this is obfuscated by the discipline's drive to isolate core phenomena. That is, it has been noted that often phenomena we observe are caused by smaller, less obvious phenomena. So, for example, attempts to make gravity fit into quantum mechanics have driven physicists to suggest that gravity as a force is mediated by a graviton, or what not. If this were ever demonstrated by experiment and became widely accepted, a laymen might ask, "why does gravity behave the way it does?" and a physicist might explain that it has to do with property xyz of gravitons. But this is not an explanation.

This is simply telling the listener that the macroscopic observable phenomenon of gravity is actually made up of several, less easily observable phenomena. This is all well and good, but you'll notice that it actually explains "how" gravity works. "Why does my house keep out the rain?" "Because it has a roof." It seems logical, but it isn't. Because the roof is how it keeps out the rain -- the reason it keeps out the rain is something much more subtle, like, "Because the designers felt that the house's inhabitants would rather not get wet."

Science answers the how of things, and it does this exceedingly well. It cannot (and for the most part, does not even attempt) to answer the why. But why and how are so muddled in the way people think that lots of folks (scientists included) are deluded into thinking that science will eventually explain the big questions like "why does the universe exist", and "why are we here."

If you've ever asked a scientist the latter question, you may have gotten something along the lines of "We're here as a result of abiogenisis, followed by billions of years of evolution, catelysed by Darwinian na

Re:A Brief Explanation

[808140]

Well, the Adam and Eve issue (as someone else pointed out) is that we don't have enough genetic diversity in one couple to produce all of humanity. Just consider the inbreeding problems that the royalty of Europe had a few hundred years ago due to intermarriage. If you wanted to populate the moon, for example, you could not just send one couple. Within a few generations, inbreeding related problems would be their downfall.

Don't get me wrong, I think it's a nice story, and it can be used (like most mythologies) to explain social issues like morality and the like, but interpreted literally it falls rather short given what we know from observation about what happens when humans reproduce with their siblings and cousins for a few generations.

Regarding Noah's Ark, this is actually a reference to a big issue in Darwin's time -- that of biological diversity. Again, Noah's Ark involves the idea of "a pair of every animal species" (which involves the same inbreeding issues as Adam and Eve) but even if you ignore that, there's the problem of the sheer number of species in the world.

See, when the judaic tribes came up with this story, their world was much smaller, and the number of species much more limited. So it seemed reasonable that an ark of a particular size could hold all the animals in the world.

But once naturalists started looking around, they realized that there were more species of animal than could possibly be held in just one ark. Furthermore, there's the issue of positioning. If you don't accept evolution, how did the animals get to their respective positions after the Flood? Did the kangaroo swim to Australia? All animals were created by god in static and unchanging way for some mystical purpose, according to religion, so after the Flood, all those animals needed to get to where the lived. Let's assume the Kangaroo did walk across Asia and then swim to Australia. Why aren't there any Kangaroos between Mt. Ararat and Australia?

How do you explain phenomena like the Wallace Line between Bali and Lombok in Indonesia?

The answer is, you don't. Noah's Ark may have been a localized occurence; there is evidence that suggests that the Mediterranean basin was once a wide and fertile valley and that a number of agricultural civilisations were destroyed as the water level rose. It's entirely possible, then, that some old guy built a boat and took his goats with him. But to extrapolate such a story to the entire world?

I could see, if you believed in evolution -- and thought major speciation could happen in just a few thousand years -- that maybe back then there were just fewer animals, and that they subsequently evolved into their current form. Of course, this isn't consistant with scientific understanding of how evolution works.

Or perhaps God created all those other Animals after the flood. Or maybe, there were many Noahs, in many different cultures, and they all built Arks. No matter how you try to explain it, though, the story as it stands is an explanation that doesn't scale.

But that doesn't mean that it isn't a great story. I enjoyed it a lot as a kid. I'll tell it to my children. But it's a story. It's like the Church saying heliocentricity was bunk. They made a mistake. So what? If your belief in God depends on a literal interpretation of the bible or other religious dogma, it's a tenous faith indeed.

Because, as I pointed out, Science can only replace the mythologies produced by religion, but it will never be able to replace the core reason for the existance of religion -- to explain why things are the way they are. There's no reason to feel threatened about modern evidence falsifying or rendering unlikely stories written by nomadic tribes millenia ago.

Re:A Brief Explanation

[808140]

I don't know... there's nothing silly, on the face of it, about unicorns. Why shouldn't there have been a horse with one horn at some point in time? It, like many other things, might just be extinct. Anyway, stranger creatures have walked this earth.

As for the Jessie Jackson bit, that truly is silly. But I think it's a different issue than the existance or non-existance of God, because your scenario serves no purpose. Don't you ever wonder why the universe exists? It all seems so perfect. I see the existance of benevolent white bearded super-being as the willfull creator of the universe as a bit of a stretch, granted. But I guess if someone were able to offer evidence that the universe had been somehow engineered, I wouldn't really be surprised. But I would just replace my "why does the universe exist" question with "why does God exist", which is equivalent. It's the whole "Unmoved mover" thing. My human belief in causality makes me wonder why things are, and anything which exists for no reason confuses me.

To me, "the universe exists for no reason" and "God created the universe for a reason, but God exists for no reason" are equivalently frustrating belief systems.

But I'll stay open-minded. I just wanted to underscore that I'm not against the notion of God in principle. I just don't think it's supportable.

No

[Rufus88]

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.

Whats frame dragging?

[EvilGrin666]

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.

Re:Isn't it time soon...

[the_mad_poster]

The easiest way to think of the distinction is that a theory is a set of calculations and observations that are used to explain some previously unexplained phenomena.

A law, however, is something that is quite set in stone. In your example, you're actually referring to a set of equations that Newton put forth. These equations are quite absolute and will always reproduce the same output no matter how often a given set of variables is retested.

Therefore, while a theory is a "best effort" explanation that tries to predict results, a law is a logical system (such as an equation) that must and will always produce the expected results given a defined starting point.

Re:Time travel

[Olathe]

If backward time travel is possible, it does not seem it would have any adverse effects. Physics does not care about your lineage. Assuming you shot your ancestor, the bullet would not mystically stop and the particles that make up your body would not mystically disappear.

It does not matter that you would not be born to go back in time. Physics does not care about you as a being. If your particles exist in a certain configuration at a certain time in the past, it does not matter that the original cause no longer exists. Physics does not care about timelines. It only cares about the instant immediately preceding the event. Only people care about unbroken chains of cause and effect, not physics.

All the confusion comes from people creating paradoxes by ignoring deterministic physics laws and imposing stupid irrelevancies.

yeah, real sad.... right....

[commodoresloat]

it's really a sad state of affairs when a glorified weblog isn't able to report news faster than a multibillion dollar media corporation with reporters stationed all over the globe.

6 feet = 1.8288 meters

[Anonymous Coward]

Not to be pedantic, didn't we learn that conversions in spacecraft need to be more precise?

Sincerely,
The Mars Climate Orbiter (AC to avoid karma whoring and giving away my location)

Re:Isn't that...

[nerdguy569]

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

Theory?

[cbr2702]

No. Not until it's proven. As long as someone could come up with another theory that predicts the exact same results, in a different way, which is not disproven, it's still a theory.

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".

Understatement of the year

[Nitish]

From the CNN article: Black holes [are] typically much more massive than Earth.

It's that stretching thing...

[rmdyer]

As a long time science buff I'm pretty well read on the various "big" theories out there relating to how the universe works. Your explanation is a good one, and tends to follow the standard space-time is a fabric, blah, blah, blah. But the things that annoy me most about modern concepts are the big ambiguities that result of some simple explanations. For example, take the concept of the "stretching" of space-time. If we up all the dimensions by 1, going from a flat sheet to a volume. We would expect that the word "stretching" doesn't fit very well. We alrady have 3 dimensions of space and 1 of time. So basically what stetching means in 3 dimensional terms is "densities" of space. More precisely we find that when large masses are placed in a space-time fabric (volume) the space around it gets more dense. If space is more "dense" around large masses then that means there is "more space" within a given volume. But what volume? Gravity waves would be seen as simply variaitions in the densities of space-time.

This all seems very strange until you read up on some of the modern concepts of vacum physics. Space is not seen as being emtpy at all. Space is actually something. Where matter within space is simply some strange configuration of whatever space is. This is sort of like ice in water, where water can be viewed as space, and ice is the matter within it. If this is true, as in the way things actually work, then everything that exists is really just one thing...the stuff that space is made of. Apparently though, this "stuff" is non-continuous, becuase how can you stretch it otherwise? It seems to have a finiteness so that, like air pressure, it gets more dense the closer you get to a massive object. In my view, the Bekenstein bound, a model for the granularity of quantum events, seems to be linked to the finiteness of space-time. The Bekenstein bound proposes that any given volume of space can only have a finite number of states. This brings about the model of a computer screen where you only have a certain number of pixels within a given area. To expand further, based on the Bekenstien bound, it would be only possible to have a finite number of physical manifestations (objects) within a given volume of space-time. In the same way, you can only have a limited number of possible pictures viewable on a computer screen within a given resolution.

Does the universe actually work this way? If it does, then this suggests the possiblity that the volume of the entire universe is a large finite state machine. Within the lifetime of the universe, the machine is working out all the possible logical permutations of reality as time progresses. What we don't know is: Is the volume of the entire universe infinite? What would be the end result of the permutations?

The contrary argument would be that space-time could actually be continuous, but that there only exists so-called quantum interfaces at a certain level. Below the level of the interfaces, we cannot know about any of the other features of space-time. The interfaces block further exploration into space-time because our measuring devices only operate at the level of the interfaces. This model is very much like working with Legos(TM). Legos blocks are finite, and they allow you to build large numbers of possible devices (objects) within a given volume of space. But Legos can only interact at the connection level. Where there are no connections, Legos cannot be known.

The more I read, the more I'm finding that modern science is telling the above story over and over again as we come to understand things better. Do you guys read the same picture, or am I just reading the wrong books?

+1

Re:A Brief Explanation -- a better analogy

[InterGuru]

The analogy of a weight on a stretched membrane is easy to visualize, but depends on a force outside the "fabric" of space - ordinary gravity.

A better analogy on how curved space can seem like a force is to look at two ships, both some distance apart at the equator heading north. For the sake of this argument, assume the Earth is totally cloud covered, and those on the surface are not aware of anything off of the surface.

The captains will see that their initial motion is parallel. They are both going in a straight line, along a longitude line, heading for the North Pole. On the surface of a sphere, as on any curved ( or uncurved) space, a straight line is defined as the shortest distance between two points. As the two ships head north, the captains will notice that they are getting closer to each other; finally colliding at the Pole.

After scratching their heads to figure out what happened, the will conclude that there was some force drawing the two ships together. From "outside" we can see that the collision was caused by the curvature of their space, but those whose motion, and vision is confined to the surface of a sphere, will give this force a name. Perhaps "gravity."