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General Relativity Is At Least 99.95% Right
ultracool writes to mention a ScienceDaily piece on compelling proof of general relativity. A team at the University of Manchester have used three years' worth of data on a pair of pulsars as a litmus test, against which they've benchmarked Einstein's theory. From the article: "Though all the independent tests available in the double pulsar system agree with Einstein's theory, the one that gives the most precise result is the time delay, known as the Shapiro Delay, which the signals suffer as they pass through the curved space-time surrounding the two neutron stars. It is close to 90 millionths of a second and the ratio of the observed and predicted values is 1.0001 +/- 0.0005 - a precision of 0.05%. A number of other relativistic effects predicted by Einstein can also be observed. 'We see that, due to its mass, the fabric of space-time around a pulsar is curved. We also see that the pulsar clock runs slower when it is deeper in the gravitational field of its massive companion, an effect known as "time dilation."'"
Observations that support a theory are nice, but they are not a proof.
I think what they mean to say is that "Reality is at least 99.95% right."
Let's not go attempting to invalidate any theories I've spent hundreds of hours trying to understand, ok?
When things get complex, multiply by the complex conjugate.
all we need are 20 pounds of trash and 1.2 jigawatts from the town square clock at midnight!
I think 99.95% is about as close to dead-on-balls-accurate as it gets with our current knowledge of the universe; I mean, there's always a margin for error in absolutely everything, it's just one of the facts of the chaotic universe in which we live. Still, it just goes to show how far ahead of the game (and of the times) Einstein was.
Einstein's still my hero. He's the Samuel L. Jackson of science.
[End of Line]
We've been testing his theories for decades now and everything he said always turns out to be right. Wow.
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How can they say anything is 99.95% right, have they never heard of the Cartesian method of doubt, I would say that second meditation doubt would weigh in at more than 0.05% on its own... I mean, how can you be sure that you're not decived every time you think of the universe or physics into thinking that this is the way it is, when it isn't. More over, how do you know the universe exists?
Over and above the possibilities of the universal physics being disrupted by deamons you have to consider that it might actually be wrong, which we'll take their word for at 0.05%... so all in all I'd say about 1-5% doubt - but you can never know
*''I can't believe it's not a hyperlink.''
"Well, I measured thousands of falling apples, my mechanics must be at least 99.95% right!"
However, General Relativity is not a proof, but a model. The various models that give us a way of understannding the world are only that: models, not laws per se.
When Newton explained gravity, he did not say that he was right. Indeed he said that the model he proposed was the best he could come up with given the limitations of his apparatus. He even predicted that his model would be superceded. And, for most people of today, the physical objects that they interact with can be adequately understood with Newtonian physics.
Einstein even said "As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality.". Just like Newton's models had limits and fell apart at some point, likely the same will happen to General Relativity when we're one day able to observe things beyond what the model can handle.
Engineering is the art of compromise.
(sorry)
"" How about taking the safety labels off everything, and let the stupidity-problem solve itself? """
I'm aware that my post was not directly responsive to your point, but I could smell it provoking an attack of the "It's only a theory" people and I wanted do what I could to head them off at the pass.
KFG
in this shop we shoot for five nines!
I figure if Shapiro can get O.J. Simpson off, he has to know something...
788652 = 2 x 2 x 3 x 3 x 19 x 1153
Ok, so Relativity and Quantum Mechanics have been beating the crap out of each other for 80 years, with no end in sight. We get it, we get it!
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
You can't measure position in quantum physics [...] As far as we known, the "particle" *NEVER* has an exact position or momentum, but rather is at an infinite set of locations.
At least in principle, you can measure position in quantum physics. The particle is temporarily put in a position eigenstate with an exact position eigenvalue associated with it (the momentum is completely indeterminate, however). This only lasts for an instant, however, before the state evolves into a superposition of position eigenstates.
Remember, it is an axiom of quantum mechanics that measuring observables puts the system in an eigenstate of that observable; the eigenvalue corresponds to an exact measurement of that observable. (You will not be in an eigenstate of any observable that commutes with it, and therefore those quantities will not be known exactly — the Heisenberg uncertainty principle.) Of course, you could quibble about our practical ability to put a particle into an exact position eigenstate, as opposed to an eigenstate of an observable merely very similar to the position operator.
Einstein's is not the only theory, and there is a major flaw in his: there is no such thing as "fabric of space-time". It's a convenient buzzword but it doesn't mean anything. This is a case of "exactly as if ..." Things work as if Einstein was right, but there is no evidence that he was right.
Here's an example: If you pass a current through a wire it generates a magnetic field. If that field crosses another wire it generates a current in that wire. It's exactly as if the magnetic field moved from one wire across the other. The flaw is that if you wrap both wires through an iron donut all the field is inside the iron - absolutely NO field is detected anywhere around either wire. The theory is false, but it is "exactly as if" it were true.
Likewise, Einstein's theory may give correct answers even though nobody actually knows why. For one thing, plasma physicists can easily explain a lot of effects in electrical terms, relying on laboratory observations instead of imagined theories. Astronomers ignore plasma physics because nobody ever taught it to them.
It is close to 90 millionths of a second and the ratio of the observed and predicted values is 1.0001 +/- 0.0005 - a precision of 0.05%.
1.0001 is *NOT* a ratio! Ratios have two numbers represented as Value X:Value Y, or Value X/Value Y. 1.0001 could be the quotient resultant of a ratio, but of what two numbers? The assumption in this case is that the ratio is 1.0001:1 based on the percentage value given by the precision of variance in the calculation, but not everyone is going to know that, especially school age children doing science papers and the like. Sloppy, really sloppy. And people wonder why we're getting worse at mathematics.
Isn't that (at most) 0.05% the most interesting part?
The more evidence we have to support the fundamentals of the General Relativity model, the more reason we have to suppose that it's more exotic predictions, such as worm holes, are correct.
Assuming we haven't nuked or gassed ourselves into oblivion, I like to imagine in a few hundred years we'll come to regard the work of Einstein, Hawking, Heisenberg, etc. as certainly great but somewhat primitive and rudimentary in our understanding of the universe.
After all, when Archimedes famously realized the principals of buoyancy around 250 BC, it was one of the revelations of its time.
I thought that the Boomerang Project from 1998 and 2003 proved that beacuse the background radiation in space was spread out the way it is, that this disproved that Space-Time was curved? Check out http://cmb.phys.cwru.edu/boomerang/. Not that I wanted this to be true, but what I watched on NASA TV in 2003 said that it was the facts. So if his General Theory is 99.95% accurate, is this the .05% variance?
"I think you know what I'm talkin' about, Mr. President; We're gonna kill us a mummy!" - Bruce Campbell as Elvis Presley
... mind translating your .sig?
Ignore this signature. By order.
Hello:
The measurement is still in the range of first order parametrized post-Newtonian accuracy. What the Donkey Kong that means is that these are the coefficients to the metric that are being tested:
dtaU^2 = (1 - 2 GM/c^2 R + 2 (GM/c^2 R)^2) dt^2
- (1 + 2 GM/c^2 R) dR^2/c^2
- R^2/c^2 dtheta^2
- R^2/c^2 sin^2 theta dphi^2
It is the 5 integers there (1, -2, +2, -1, -2) that are confirmed by this experiment. That is NOT NEWS, because it is not new. Shapiro got the same results. What would be news is if the experiment got to second order parameterized post Newtonian accuracy. I asked Prof. Clifford Will an expert on experimental tests of GR when where the data hunters going to gather that data. He said he knew of no one even discussing it. The reason is that the data must for 2nd order PPN effects must be a million fold more accurate, so we need data that is 99.99995% accurate.
I care a lot about 2nd order PPN tests, since that is were my proposal to unify gravity and EM using a 4D wave equation differs. GR says the metric should go here:
GR:
dtaU^2 = (1 - 2 GM/c^2 R + 2 (GM/c^2 R)^2 -3/2 (GM/c^2 R)^3) dt^2
- (1 + 2 GM/c^2 R + 3/2 (GM/c^2 R)^2) dR^2/c^2
- R^2/c^2 dtheta^2
- R^2/c^2 sin^2 theta dphi^2
GEM (gravity and EM):
dtaU^2 = (1 - 2 GM/c^2 R + 2 (GM/c^2 R)^2 -4/3 (GM/c^2 R)^3) dt^2
- (1 + 2 GM/c^2 R + 2 (GM/c^2 R)^2) dR^2/c^2
- R^2/c^2 dtheta^2
- R^2/c^2 sin^2 theta dphi^2
At first order PPN accuracy, the coefficients (1, -2, 2, -1, -2) are the same. At second order, they are different. That's the data I need. I'll probably be dead before it shows up.
doug
Working on new views of old physics at http://VisualPhysics.org
Isn't Einstein's relativity just a much smaller magnitude extra term on Newton's mechanics? Negligible at human scales. Einstein's correction to Newton was much less than 0.05%. If relativity is really as much as 0.05% off, that leaves a vast amount of unexplained phenomena in our big Universe.
--
make install -not war
huh?
I do hope they're not actually teaching this in science classes! Darn Evilutionists must be everywhere. Where's my theory of Creative Gravity, eh?
Ok, let's try this: "the earth just sucks!"
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."
--Donald Rumsfeld
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As a result, the best we can say is that the theory we have put together fits the observed data to a high degree of precision - but that this may be invalidated at any time by new phenomena. See, for example, the progression from Newtonian mechanics to Relativity, or the long-running debate over the nature of light.
Well, no, that's not the "best" we can do. It is quite possible to prove theories to be correct experimentally, if you formulate the theories correctly and then conduct the right kinds of experiments.
The problem is that General Relativity, like most physical theories, was pulled out of a hat and has caught on because it's appealing to physicists. Furthermore, the experiments being conducted to test those theories are chosen rather haphazardly. For those kinds of theories and those kinds of experiments, it is indeed impossible to prove anything
There's no such thing as proof of a scientific theory, so talking about how a theory is "almost proven" is just plain wrong.
And trying to quantify the "provenness" of a theory with a figure also shows a deep misunderstanding of how science works. There are any number of quantifiable tests that have matched general relativity's predictions, and each of these have different error bars. So picking one at random and using it as the measure of how "proven" general relativity is doesn't make any sense at all.
Since when is 99.95% a big number when we're dealing with astronomy? I think Newton's laws are precise within 99.95%.
99.95% of what?
http://outcampaign.org/
99.95% correct still leaves tremendous room for unknowns. It's that last 0.05% where all the interest lies - where we fail to predict accurately because we are wrong about whatever is occuring.
..........FULL STOP.
Wow, when did you go to school? I learned sqrt(-1) = i in the 10th grade... However, point taken.
The part about "physics and other sciences" is dead on. The only true reality is the position and momentum of the base particles. Everything else are just stories, accurate to some degree - or as you state, "partial data".
However, your statements about math are off insomuch as you use the word "all": one of the most fundamental parts of math and logic were Godel's Incompleteness theorems in the 30s. This is the mathematical codification that Hericlitus ("We both step and do not step in the same rivers. We are and are not." - Wkpda) and the Buddha had it right, (to the Buddha, the Absolute Truth was that "there is nothing absolute in the world, that everything is relative, conditioned and impermanent, and that there is no unchanging, everlasting absolute substance like Self, Soul, or Atman within or without" - Rahula, p.39) and that if you can and do go deep enough, relativism wins, unequivocally.
For practical, day-to-day operation, pragmatism often wins, but only if you allow arguments that restrict your context.
Also, in my opinion, we don't define the rules in math, we discover them.
Here is the real mind blower: As much as we will structure and codify, even with ALL the data we will not reach logical consistency on everything. Building systems with that end will ultimately fail.
I think Newton's laws are precise within 99.95%.
Well, they are (up to about 0.6 c, at least,) but that's not the point. Indeed, the disparity between expected and measured data is less than 0.01%, which is also specifically mentioned in both the writeup (phrased as the measurement ratio and posited as 1:1.001) and in the article.
99.95% of what?
The ±0.05% refers to the accuracy of the measurement used to glean the data, and has nothing to do with the theory or the difference between the expected and measured value. They're codifying the error tolerance of the pulsar measurement.
StoneCypher is Full of BS
[quote] General Relativity Is At Least 99.95% Right [/quote]
.05 % due to observational error .
It could also be argued that the test measurements off by
http://en.wikipedia.org/wiki/Measurement_error
What he said.
-Clio
Karma: Bad (mostly from not giving a fuck)
Blog: http://clintjcl.wordpress.com
Hmmm... doesn't have quite the same ring to it.
;-)
And oh, my bad, that's special relativity, not general relativity
one thing i never quite saw clarified is why scientists deduct that time warps just because a time-measuring device measures time differently under different conditions. couldn't it be that whatever underlying mechanism slows down or accelerates, while time itself ticks at the same rate? and how could you even see the difference?
Theories are generalizations about systems. Some generalizations are better fits to realty than others.
The clearance system sounds logical. It is not. It is completely arbitrary. -- John Bolton