Frame Dragging by Earth Reconfirmed 379
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."
networks (Score:4, Funny)
Re:networks (Score:5, Funny)
Re:networks (Score:3, Funny)
Isn't that... (Score:2, Informative)
Re:Isn't that... (Score:5, Informative)
-HJ
Re:Isn't that... (Score:5, Informative)
Re:Isn't that... (Score:3, Interesting)
What's really impressive is the transformation from silver into copper!
Re:Isn't that... (Score:3, Interesting)
Hey, I said the story was apocryphal. It may be BS but it persists because it captures a grain of truth about the way Americans approach major technical problems.
Graphite is a conductor, so you don't want its dust floating around in a spaceship where it might short something out. Russian reactors (some of them) use graphite as a moderator, to slow down neutrons without absorbing them. We use heavy water. And there you go- that's another example. We go through all this trou
Ouch... (Score:4, Funny)
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
Re:Ouch... (Score:3, Funny)
Jeez. Get your obscure internet references correct prior to posting.
Re: (Score:3, Funny)
Re:Ouch... (Score:4, Funny)
Re:Ouch... (Score:3, Informative)
According to current results, the theory may be correct (may be even "is likely to be"). But of course, we need more precise measurements.
Why, this explains why.... (Score:5, Funny)
Re:Why, this explains why.... (Score:2, Offtopic)
Comment removed (Score:5, Funny)
Re:Yo mama (Score:2)
Yo mama's so fat, she only a donut away from changing the tide!
Re:Yo mama (Score:3, Funny)
GR lives on and on (Score:5, Interesting)
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 (Score:3, Insightful)
What are you looking for? There's no such thing as "certain." In fact, this result is excellent--with 10% error bars, I'd be ecstatic to agree with predictions within 1%.
99% +/- 10% is far better than 99.9% +/- .01%
Re:GR lives on and on (Score:2)
Maybe... but when you compare the two, isn't 99.9% +/-
99% +/- 10% might get you within range of your prediction, but the more precise result may actually indicate that your predictions are not complete.
As for me, I suppose I'd prefer my data and analysis be sound, even if it means I have to revise my predictions.
Re:GR lives on and on (Score:2, Insightful)
99% +/- 10% is far better than 99.9% +/- .01%
Not at all. That +/- 10% is there for a reason. The margin of error is just that--a margin within which error could have occurred. The true value could easily have been 92% or 105% the predicted value, but the error caused it to become closer to what was expected. I'd be more interested in the latter example, as deviations that small usually indicate that we're on the right path with minor reworking.
Re:GR lives on and on (Score:5, Informative)
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 (Score:5, Informative)
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 (Score:3, Informative)
Besides, I was under the impression that Frame Dragging was already verified experimentally among certain other massive astronomical bodies out there.
Re:Don't Get TOO Excited (Score:5, Interesting)
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 (Score:3, Informative)
It's just that it is easier to observer the phenomenon around blackholes owing to their massive nature.
It's just the -actual- curving of space-time around massive bodies that affect the way objects are drawn towards the massive body.
Re:Don't Get TOO Excited (Score:2, Informative)
Agreed, but we're talking about two different things now. It's definitely been observed in the cosmos, but AFAIK this is the first experiment that tentatively confirms the phenomenon.
Re:Don't Get TOO Excited (Score:2)
I get you now.
What I meant was that this is merely an observation, there are some things in nature I do not quite think we can prove completely through purely experimental means except through observation.
I suspect if even the LIGO and LISA experiments conclusively -prove- it experimentally, I think they are more of particular measurements and observation.
Re:Don't Get TOO Excited (Score:5, Interesting)
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:Don't Get TOO Excited (Score:2, Funny)
The accuracy of TRUTH has been determined to suffer a truth variance. Politicians are known to spin yarn and alter the very fabric of space, time, and facts usually accepted without question. However, due to their dragging the truth so far as to rip the facts from the framework, the results are about only 10% accurate.
There is a margin of error of this report of about
Isn't it time soon... (Score:3, Insightful)
Re:Isn't it time soon... (Score:3, Insightful)
For example, 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."
Yes, this makes truly proving anything in the physical world basically impossible.
Theory? (Score:5, Informative)
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".
Re:Theory? (Score:4, Insightful)
You make an excellent point here, but not the one you think you do. Ockham's Razor, as you point out, advises us. It says that the least complicated explanation for observed behaviour is probably the correct one. It does not say that it is definately correct. It simply allows us to predict which of several explanations is most likely to be correct based on our past experience that things are usually simpler rather than more complicated. Ockham's Razor, four thousand years ago, would have had us believe that the stars were little point-sources of light floating just above the clouds. Certainly that was a more simple explanation of our observations than the idea that they were huge self-sustaining fusion reactions happening thousands of light-years across a limitless universe.
~Benjamin
Several misconceptions (Score:3, Informative)
Axiom in epistemology is a self-evident truth upon which other knowledge must rest, from which other knowledge is built up. To say the least, not all epistemologists agree that any axioms, understood in that sense, exist.
Axioms in mathematics are not self-evident truths. They are of two different kinds: logical axioms and non-log
Re:Isn't it time soon... (Score:3, Insightful)
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.
For example, 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."
You joke, but interestingly enough, something like that has happened. Newton came up with a set of "laws" for the physical universe, and
Re:Isn't it time soon... (Score:4, Insightful)
Re:Isn't it time soon... (Score:4, Informative)
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.
In contrast to human laws... (Score:4, Insightful)
In contrast to human laws, which just 'become' without any evidence in their favor (and then presented as absolute truths).
Yes, I've always known that mother nature is far better at creating sensible & logical constructs (and enforcing them)...
Re:Isn't it time soon... (Score:2)
A law is essentially an axiom, and GR is not yet.
Atleast not until all aspects and effects of it are proven completely.
No (Score:5, Informative)
Re:Axioms? (Score:3, Interesting)
"Law" is definitely not a synonym for "axiom". I think the grandparent poster is rather confused. A "law" is not just something that we have observed to be true and then taken for true (i.e. taken to be an axiom). Rather, "law" is a term that has just been loosely applied, suggesting more strength than a "theory", but both pieces of scientific knowledge are not to be considered inf
The Laws Of Relativity? (Score:3, Funny)
I don't think so. Legislation is not the answer to every problem.
Re:Isn't it time soon... (Score:4, Insightful)
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.
Not Very Accurate (Score:2)
Hmm... I don't know that results that are only 1% accurate are particularly meaningful in any measurement or experiment. I assume that they actually meant accurate to within 1% but that would be 99% accurate...
Or am I completely missing the obvious again...
Re:Not Very Accurate (Score:2, Informative)
Re:Not Very Accurate (Score:2)
This of it this way: if the actual value is 0.00, then by your definition, the probe will make a perfect measurement.
Re:Not Very Accurate (Score:2)
Re:Not Very Accurate (Score:2, Informative)
2 meters is about 6'7", or 6 feet is about 1.82 meters. So which is it?
The metric system strikes again, I guess.
This project was batshit nuts (Score:3, Informative)
Crazy shit.
No, you're wrong. (Score:5, Informative)
Re:This project was batshit nuts (Score:3, Interesting)
Actually, they are only the most spherical things in our little region of the galaxy. Neutron stars (of which the closest known is a couple hundred lt-yrs away) are even more spherical.
And yes, IAAA (I am an astronomer).
Re:This project was batshit nuts (Score:4, Interesting)
Re:This project was batshit nuts (Score:2)
This project was batshit nuts
I think that very phrase will appear in the abstract.
Some Equations (Score:4, Funny)
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 (Score:5, Funny)
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:Some Equations (Score:3, Insightful)
Re:Some Equations (Score:4, Funny)
f-r/e^d
You were describing a formula developed by Gwynne(65) and further developed by Sanford(73), and Schneider(77).
Sanders' Equation was:
hAr/(l^An)
where h is Planck's constant, A sub r is the acceleration frame relative to the rotating mass, l is the angular momentum, and A sub n is the acceleration frame normal.
I understand this formula works for 11 dimensions (or "vibratory branes"... often referred to in terms of "hertz and spaces"), but no one besides Sanders seems to understand exactly what they are.
Just like Relativity which has the Special and General versions, this also has two versions, related to General Relativity and M-theory respectively.
These are commonly referred to Regular and Extra Stringy.
Re:Some Equations (Score:2)
More Info on twisting Space (Score:5, Informative)
Perhaps (Score:5, Funny)
"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 (Score:5, Funny)
A Brief Explanation (Score:5, Interesting)
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?
Stupid question time... (Score:2)
I've been vaguely looking around for more information on that. From what I can gather, it's a reproducible observation, but other effects haven't been ruled out, so no one's sure what to make of it.
It's that stretching thing... (Score:5, Insightful)
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
A Sheet Of Paper and a Weight? (Score:3, Insightful)
Without the force of gravity all the objects would remain where they were, regardless of the deformation of the paper. They wouldn't even stay on the paper, they would just float.
I know there's real, valid science behind relativity. I just would like to request a better metaphor. Or a better explanation. Or maybe just a turkey sandwich.
That is al
Re:A Brief Explanation -- a better analogy (Score:5, Insightful)
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."
Re:A Brief Explanation (Score:4, Insightful)
The idea of independent frames of reference only holds for velocity. Rotation of an object involves acceleration towards the center of that object. Each point on a rotating circle moves tangentially to the circle, but that velocity is changed (accelerated) as it goes, because the tangent to the circle is different at each point it moves through. Thus, there is no rotating frame of reference for the earth.
To test this idea in simpler terms: if you're in a zero gravity environment, and you're spinning, what happens when you pull your arms in? You start spinning faster, right (conservation of angular momentum and all that)? Well, if instead, you're stationary and the thing you're in starts spinning, what happens when you pull your arms in? Nothing! It's the rotating thing, not you, thus you have no angular momentum to conserve. If rotation was just another frame of reference, then to be consitant, when you pulled your arms in, the same thing would have to happen: the relative rotational speed would have to increase.
Incidentally, that's also why we can definitely say that we orbit the sun, not the other way around.
I hope that clears that up.
b.c
Re:A Brief Explanation (Score:5, Insightful)
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 (Score:5, Interesting)
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 (Score:4, Informative)
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.
Bad example -- the Eve Hypothesis [wikipedia.org] seems to indicate that all of humanity is decended from a relatively "small" population of humans (where "small" is defined as less then 20k).
There is also a corresponding Adam Hypothesis [wikipedia.org]
In science, tiny populations can give rise to large populations (Founder's Effect [wikipedia.org]), although sometimes there are side-effects.
Wisent (European Bison) [wikipedia.org] are all decended from twelve individuals. Wisent bulls suffer from some lack of diversity, only having two distinct Y-chromosomes in their genetic pool, but there are only limited effects from interbreeding.
Golden Hamsters [wikipedia.org] tend to be all decended from one litter found in Syria in 1930.
IIRC, Noah was supposed to have several people on the Ark -- himself, his children, and his children's spouses. Although clearly not an optimal setup, it would probably be enough to prevent the species from dying out.
I wouldn't be surprised if some islands in the world started out with roughly the same population.
Don't get the wrong impression -- I'm not arguing for Creationism or literal interpretations of the bible. I just don't want to see bad science being repeated.
Re:A Brief Explanation (Score:3, Interesting)
Unfortunately, it's not. How many people are needed to create a genetically viable population varies very much on the individuals concerned, but the lowest number I've ever heard is 60 -- 60 completely unrelated individuals.
Rather more than 5, at least.
Re:A Brief Explanation (Score:5, Insightful)
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.
Inertia (Score:3, Informative)
The moon doesn't move into the depression. The moon , like every other object, keeps traveling in a straight line until it collides with something. All the depression does is change the shape of a straight line. Any object in "free fall" is travelling in a straigh
Because the rubber sheet's an inexact metaphor (Score:3)
You're thinking too deeply for the popular metaphor, which is for use by people who don't want to think deeply.
Here's a better metaphor, but still stopping short of the math. I've asked a PhD general relativist for commments: he didn't seem happy but had no direct objections.
Imagine the upp
Whats frame dragging? (Score:4, Informative)
Thanks! (Score:2)
Mayube something simpler? (Score:2)
- atmosphere: although it is very thin by that point there is probably still enough to cause drag, even if we are talking decimals
- Earth gravity: the Earth still has a gravitational effect even at that distance, so taking into account the pull down would reduce the forward vector of the satellites
- Moon or Sol gravity: pretty much anything large enough has a gravity that will effect objects close by.
Beca
Re:Mayube something simpler? (Score:4, Informative)
frame dragging was predicted in the early 1900s by the various equations that make up relativity. if we were to observe that it wasn't happening and some other effect were causing it, then that would be very odd indeed, as that would imply that all the equations which have been right in so many other ways are wrong in this one little regard making things much much more complicated.
The simplest possible explanation for this is frame dragging.
Also, the gravity effects you mention would not affect the sattelite in this way, a downward pull has no effect on the horizontal motion of a satellite and the moon and suns gravity can easily be accounted for. Also, imagine the root cause was the moon and suns gravity, then that would imply there is something fundamentally new about the gravitational laws we do not yet understand, which again is very interesting and much more complicated than frame dragging.
Re:Mayube something simpler? (Score:3, Interesting)
You're not recognizing just how sensitive and sophisticated measurements and calculations of Earth's gravitational field have become. It's been well over a decade now since I read of how a satellite was used to create new and detailed maps of the ocean floor by measuring local variations in sea level; because rock is more dense than water, a seamount a mile below the ocean's surface creates a slight increase in the local gravitational pull, causing the ocean to hump up slightly above the mount.
The articl
Re:Mayube something simpler? (Score:2, Insightful)
I do believe that they factored in the earth's gravitational pull, considering that is what
6 feet = 1.8288 meters (Score:4, Funny)
Sincerely,
The Mars Climate Orbiter (AC to avoid karma whoring and giving away my location)
Re:Wrong (Score:3, Insightful)
Some question that can be answered ? (Score:3, Interesting)
- If the earth's spin warps space around the planet what else is created by others planets or, what's a galaxy's effect arounds or inside itself ?
- Will this fabric help us to travel farther without a conventional energy ?
- Is the actual space station fullproof against anykind of fabric ripples ??
Understatement of the year (Score:5, Funny)
Relativity and Einstein on Project Gutenberg (Score:4, Informative)
Comment removed (Score:4, Interesting)
Gravitational non-uniformity of a black hole? (Score:3, Interesting)
Consider measuring the non-uniformity of frame-dragging of a black hole. If there is any, that would imply a non-uniformity in the matter in the black hole. Through this, we can determine something about the nature or distribution of the matter inside of the black hole, even though we cannot directly observe it (without being spaghettied).
So, you CAN get information back out of a black hole after all! (Although string theory already tells us that.)
great, another term to abuse on star trek (Score:3, Funny)
Re:CNN beat you to this punch (Score:2)
It links to the cnn article...
Re:CNN beat you to this punch (Score:3, Informative)
The original linked article IS CNN's writeup. Read the Nature article. CNN may have beat them to the punch, but there's some question as to the accuracy of these findings that CNN conveniently didn't mention.
Re:CNN beat you to this punch (Score:3, Funny)
Read this hours ago on CNN, doesn't seem too interesting yet."
Where did you think the submitter got the story, you insentive clod!
yeah, real sad.... right.... (Score:5, Funny)
Re:Time travel (Score:2)
Re:Time travel (Score:3, Funny)
Re:Time travel (Score:5, Insightful)
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.
Re:Time travel (Score:2, Insightful)
Most theories with paradoxes are based on the idea that the universe will suddenly act strangely because it somehow notices there is no longer a cause for the particles to be in the place where they are now. Again, the universe does not care about cause, it's mechanistic
Re:Time travel (Score:4, Informative)
The confusion comes from classical mechanics, where we typically would model real-world behaviour parametrically -- and time was the parameter. So for example, we would explain the movement of a particle as vector function of time. This works fine, most of the time. But it isn't general enough.
Relativity showed that time is not a parameter anymore than classical dimensions could be considered a parameter, it's just that we perceive it that way. Time is actually a quantity much like space. It doesn't behave exactly the same way, but that's a result of the metric of the spacetime continuum (see Lorentz transforms in Special Relativity for an example of this).
So, now we have a particle occupying a position (x,y,z,t) instead of occupying a position (x,y,z) at a particular time t. In the same way that we accept that a particle can retrace its path when moving along the x axis, we must accept that a particle can move backwards on the t axis (it just isn't thermodynamically efficient to do so).
Let's talk about you and your grandfather. Your grandfather is at point (x,y,z,t) and you are at point (x',y',z',t'), presumably with t' > t. You time travel back to time t, and kill him. He ceases to exist at (x,y,z,t).
Now, because time is a positional coordinate, if you will, and not a parameter, you have not "arrested his movement". People like to wrap their heads around this by imagining that in changing the past you have "forked" the universe and that this new forked version will never produce you, but you aren't destroyed because you come from a different version of the future.
The point is that physics doesn't care why you came into being, only that you came into being. You exist; you will not cease to exist just because the thing that "created" you was destroyed. This leads philosophers to suggest that everything exists inherently, and that we just pick our way through a myriad of decision universes. It's a way of making our logic apply to physics. At the moment there's no evidence for it.
The "kill your grandpa" paradox was used in the old days to explain why time travel was impossible; and yet time travel is manifestly possible, even if harnessing it poses an engineering problem. It happens at the particle level all the time (positrons are electrons moving backwards in time, says Feynman). This suggests, then, that our starting principle is flawed (reducto ad absurdum). The "fall guy" in this case is causality. Causality doesn't matter. We hold on to it because we have memory. But cause can follow effect, etc... I mean, it's a bizarre world we live in.
Re:Time travel (Score:3, Interesting)
If the whole idea of superstrings and 10-N dimensions are correct, then there are an infinite universes. The superset of these universes would include every possible random quantum event, and every effect from each.
In order to travel from one time to "another", you actually would guide to a universe very close to your diversion rate. You could kill off everybody, and it wont effect you at all. Then again, returning back to "your" time is impossible, as you can only approach your universe as a