Slashdot Mirror
Einstein's Theory Passes Strict New Test
FiReaNGeL writes with an excerpt from a story at e! Science News: "Taking advantage of a unique cosmic configuration, astronomers have measured an effect predicted by Albert Einstein's theory of General Relativity in the extremely strong gravity of a pair of superdense neutron stars. Essentially, the famed physicist's 93-year-old theory passed yet another test. Scientists at McGill University used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to do a four-year study of a double-star system unlike any other known in the Universe. The system is a pair of neutron stars, both of which are seen as pulsars that emit lighthouse-like beams of radio waves."
...is the value of good old-fashioned study.
Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear
in summary:
1. GE says two objects can cause a wobble in each other's axes due to gravity
2. Measurement of this wobble wasn't possible earlier
3. With this star system, since they are massive and pulsate, and that they are aligned in a manner that makes a measurement possible, astronomers took the plunge
4. Prof...proved.
An overview presentation of the capabilities of Pulsars has been uploaded to Youtube.
Einstein has yet to prove why hot dogs and hot dog buns come in inequal quantities.
http://twitter.com/OLDTELEGRAM
That there isn't any type of classification in between LAW and THEORY
Makes things like this sit in the same bucket as one of my drunken musings. "I have a theory that.... in..... etc". There should be a state of a theory where they can say "Well, we can't yet prove all of it, but we have managed to prove x amount, or in x years of testing, it has yet to be unproven".
Maybe term it Conjecture? It's the fitting word to use.
Moved to http://soylentnews.org/. You are invited to join us too!
Consider, as examples, Newton's laws of motion, or the laws of thermodynamics. Newton's theory of motion is deduced from his laws; the conventional theory of thermodynamics, likewise.
I say this because there are plenty of non-scientists who deliberately attempt to exploit confusion induced by popular use of the terms "law" and "theory" so as to imply that scientific theories, notably the theory of evolution, are held tentatively.
Wikileaks, no DNS
Usually pop culture gets these people's character pretty wrong. Elvis, for example, is "the King", when he was just a singing truck driver.
But Einstein they got pretty right. Sure, he didn't know everything, was smart really only within his very narrow discipline of mathematical theoretical physics. Einstein himself used to say "I really only ever had 4 good ideas, and 2 were wrong". But the couple he was right about, he was really right.
And with the wild hair, the pacifism, the "same suit every day so I don't have to waste time thinking about it", and the snappy short equations that explain everything, he's probably the coolest smart guy since they all used to wear togas and live on wine and souvlaki on the beach.
--
make install -not war
If they want to REALLY test a theory, they should just post it on slashdot. You know, because mass opinion is what really matters, regardless as to what's right and wrong.
+1 IDisagreeSoHeMustBeATrollOrAnAstroturferOrAShill
I hate it when people discuss science in this banal way. It is as if they think that the physical theories are what cause nature to act (the Laws of Nature). This is wrong. These physical theories only describe how nature appears to act. Quantum mechanics is a classic example. Look at all the different formulations that describe how the state vector or wave function or whatever you want to call it acts (Heisenberg's, Schrödinger's, Dirac's, Feynman's, etc.). They are all good theories because they explain the experimental evidence, they are simple, and they can predict things. Take a look at the so-called wave-particle duality. A photon, for example, doesn't act as a wave or as a particle. It acts as a photon (paraphrasing Feynman). We only describe it as acting as a wave or a particle.
The truth about science is that it may very well not be possible to understand why the Universe acts as it does. It may not even be possible to understand the most basic laws governing it. But we can certainly study and try to understand its behavior where we can observe it. General relativity does that well, and quantum mechanics does that well. Calling one right and the other wrong sort of loses its meaning in this context when both theories describe their data exceptionally well for the ranges that they observe. Neither of them proposes to govern nature, nor should we ever expect that of a physical theory.
Feynman's take was that light is *always* particles. He was unequivocal about that.
Lame /. posts produce wobble?
Freedom is assumed. Then they try to take it away. The degree to which you resist is the degree to which you are free.
You are exactly right, but to paraphrase:
"All models are wrong, but some are useful."
... and still they are gonna go without any real proof that the LHC won't kill us, and turn it on.
Ironic, ain't it?
Calling one right and the other wrong sort of loses its meaning in this context
I agree. Once again science... REAL science, is never about "right" or "wrong". It's about "can I use what you just told me in a predictable manner?". If it's BS and it doesn't work, then leave me alone I have stuff to do. :)
Seven puppies were harmed during the making of this post.
So, more evidence supporting general relativity, but we still insist on viewing it as an approximation of a quantum-mechanical system (like how Newtonian physics can be viewed as an approximation of relativity).
Um, no, no one insists that you view it that way.
My understanding is that relativity has been directly observed several times, whereas quantum theory is still just based on the interpretation of a series of controlled laboratory experiments, which mostly amounts to sifting through the wreckage of a high-energy collision and trying to derive the original state from the leftover pieces.
No. Relatively and quantum theory are only directly observed on the pages of scientific journals, since they're theories and that's where you observe theories being printed. If you mean the predicted effects of the theory have been observed, this is true, but the same is equally true of quantum theory, in far more contexts that you mention (just as relativistic effects have been observed in more than just the bending of light during an eclipse).
Isn't it about time to abandon the concept of the graviton and just accept that gravity is not a fundamental force, but is simply the observed effect of the curvature of spacetime due to the presence of matter and energy?
Nope. Impatience does not suit science. Easier problems have taken multiple centuries to get right -- quantum theory is barely a century old, and has been one of the most spectacularly successful theories in the history of science. It has rough edges and will take time to work it all out, to be sure, but if it suggests something is right, it takes a bit more than a short period of time looking with inadequate instruments and incomplete understanding to declare it definitely wrong on the subject.
There's a saying in engineering: When all you have is a hammer, everything starts to look like a nail.
Of course it does, to an engineer. Engineers rarely have the patience for actual science. Taking a few centuries to hone a tool isn't practical. But science isn't about practicality.
"Convictions are more dangerous enemies of truth than lies."
My understanding is that relativity has been directly observed several times, whereas quantum theory is still just based on the interpretation of a series of controlled laboratory experiments, which mostly amounts to sifting through the wreckage of a high-energy collision and trying to derive the original state from the leftover pieces.
Oh, just based on a series of controlled laboratory experiments. Unlike relativity??
I have no idea what "directly observed" means, but quantum mechanical behavior is no less directly observed than relativistic behavior. In fact, it is far better studied, since atomic physics is more accessible to experiments than relativistic physics. And it by no means is limited to high energy colliders (which is where you tend to see relativistic effects the most, by the way); atomic spectra, basically all of chemistry, condensed matter and material science, lasers, etc. all depend on quantum physics. Indeed, the quantum theory of electrodynamics is the most precisely verified theory in the history of physics; some of its predictions (like the electron g factor) are accurate to something like 12 decimal places when compared to experiments.
Isn't it about time to abandon the concept of the graviton and just accept that gravity is not a fundamental force, but is simply the observed effect of the curvature of spacetime due to the presence of matter and energy?
If you accept that matter is described by quantum mechanics, then general relativity is wrong, because you can't consistently couple a classical field to a quantum source. (Consider what happens when you want to describe the gravitational field of matter which exists in a quantum superposition of states.) Believe me, if it were that easy to produce a theory of gravity which is consistent with what we know about matter, people wouldn't have been searching for 50+ years for a theory of quantum gravity.
Once you accept that gravity needs to be quantized, then you are inevitably led to something like a graviton: it's what you get when you quantize the linearized approximation to general relativity, and is actually more general than that: any field which couples to stress-energy (which is the source of gravity in general relativity) is described by a rank-2 tensor, which in quantum mechanics means a spin-2 particle (graviton). A theory of quantum gravity won't have gravitons as truly fundamental — the perturbative theory of gravitons is inconsistent — but any such theory (e.g., string theory, loop quantum gravity) will necessarily have graviton-like behavior as a low energy limit, assuming that it also has a relativistic theory of gravity (like general relativity) as a classical limit. That is not inconsistent with GR's description of gravity as curved spacetime: that's the classical behavior of a graviton-like field, although different theories recover that limit in different ways. (String theory has strings which vibrate in graviton-like ways which are observationally indistinguishable from spacetime curvature; other theories try to quantize geometry directly.)
Being out of touch with today's society is one of the most important functions of the Senate.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
The word you are searching for is hypothesis.
There are 4 terms that need to be understood in the realm of science - hypothesis, theory, law & fact. They are all separate & distinct, except for the only progression that occurs - hypothesis => theory.
A fact is what has been carefully observed.
A law describes that observation.
A hypothesis is a proposal intended to explain that observation.
A theory seeks to explain that observation & has been confirmed by considerable evidence and has endured all attempts to disprove it.
example:
Fact
Objects fall at the same rate regardless of mass.
Law
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/circles/u6l3c1.gif
Hypothesis => Theory
Mass causes a curvature of spacetime which creates the effect of gravity.
My understanding is that relativity has been directly observed several times, whereas quantum theory is still just based on the interpretation of a series of controlled laboratory experiments, which mostly amounts to sifting through the wreckage of a high-energy collision and trying to derive the original state from the leftover pieces.
Nope. Quantum mechanics is vastly, overwhelmingly, massively tested. Compared to general relativity, quantum mechanics is easy to test in the lab, and there are many many many experimental validations of it
And general relativity, also, is getting to be well tested.
Both theories have passed all the tests that they have been put to.
The problem is: quantum mechanics becomes important for things that are very small. General relativity becomes important for objects with strong gravity. The only range where you can test both of them together is if you can find objects that are both extremely small, and have extremely high gravity. Unfortunately, that realm is outside the experimental range of any experiments, now or anytime in the forseeable future.
http://www.geoffreylandis.com
Now THAT is a summary
Actually I recommend reading the article. It's short, understandable, and contains other cool facts about these neutron stars.
Also, as for that last "proved" bit, the article ends with:
"It's not quite right to say that we have now 'proven' General Relativity," Breton said. "However, so far, Einstein's theory has passed all the tests that have been conducted, including ours."
yes, but the hard problems, like interstellar travel, will best be solved by a theory which holds up at all levels, quantum, micro, macro, and cosmological.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
Except that isn't possible, because theories that hold up well at describing things like gravity on a large scale break down horribly at the quantum level. Even basic interactions between particles cannot be described in the sense of, say, a truck hitting a telephone pole.
person A: "one day, man will fly"person B: "Except that isn't possible, because man was not born with wings!"VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
Why prove it wrong? Perhaps its not possible to rectify the way matter curves spacetime at the quantum level, perhaps Einstein doesn't need to ever be proved wrong for the description of the entire universe to be expanded upon. Perhaps there's nothing wrong at the quantum end of the scale, its just asking the wrong question.
A statistician said that. You know what they say about statistics, right?
You are aware that "impossible" means "cannot be done" and not just "we can't do it right now", right?
Blasphemers! Model != Reality. The model is our best representation of how reality works. Models are never "proven," they simply have not yet been falsified or have only been falsified under specific conditions. The longer they stay unbroken, the more reliance we place on them. But, at no point do they become the reality they were created to represent. Recant, you unscientific rabble.
Invenio via vel creo
REAL science, is never about "right" or "wrong". It's about "can I use what you just told me in a predictable manner?". If it's BS and it doesn't work, then leave me alone I have stuff to do.
What you're describing sounds more like engineering than science, you know. As an engineer, I don't care too much about why nature acts the way it does - as long as I can find a usable method to get things working the way I need them to work. I take the pragmatic approach, because I have a real-life goal.
Science, on the other hand, is not per se concerned about "using what you just told me", it's about discovering the whys and hows. Mathematics is "REAL science", as you put it, and they are most definitely concerned about "right" and "wrong". Engineers use the model that works best for them, while scientists are coming up with the new models (or trying to consolidate them into grand unifying theories, as usual).
CJ
PS: yeah, I noticed the smiley.
Ah, arrogance and stupidity, all in the same package. How efficient of you. -- Londo Mollari
Lecture 1-1 of the Feynman Lectures in Physics that he gave as a two-year undergraduate course in physics at Caltech.
There are three kinds of lies: lies, damned lies, and absurd generalizations that fail to take into account the manifold subtleties of their subject?
My understanding is that relativity has been directly observed several times, whereas quantum theory is still just based on the interpretation of a series of controlled laboratory experiments, which mostly amounts to sifting through the wreckage of a high-energy collision and trying to derive the original state from the leftover pieces.
Congratulations you have viewed Quantum Theory in action; that computer you used to post this message is solidly based on Quantum Mechanics. No Quantum mechanics, no CPU.
If someone is passing you on the right, you are an asshole for driving in the wrong lane.
Not sure if you're talking about superluminal travel or subluminal travel.
Theory already allows slower than light travel. You're spaceship would have to be big. VERY big. But if we really wanted to we could probably send mankind to the nearest stars with current technology.
But superluminal travel is a different kettle of fish. There are only two possible universes, one where there's an upper limit in the speed of information and another where there is no upper limit. The two universes have very different characteristics and our universe appears to be the smaller. It's hard to think of a way where you can transmit matter without also allowing information transfer.
Of course, even today faster than light travel is possible by current theory - but only by points A and B separating faster than light, not by allowing points A and B to communicate faster than light. Effectively this means that the speed of light is only constant locally. Maybe it would be possible to reverse the expansion and shrink the universe so that although the speed of light would still be an upper limit, communication between A and B could occur in less time than light could make the journey in a flat universe.
But I'd wager that faster than light travel in the special relativity sense is, and always will be, impossible.
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
Ok, but to clarify for some readers, "particle" does not mean corpuscular like a tennis ball, which is why the term "particle" tends to be a little misleading. In fact, it is why any "it's like a " phrase tends to fail, and why it was such a shock to discover indeterminable states to begin with. Quantum theory rests on the (unsurprising) revelation that at small scales, things are not as we have always visualized in the large, solid man-world. I don't think anyone other than Bohr was comfortable at the time with *any* explanation of some of these phenomena, even with models that were so fucking accurate.
And light does travel in wave form. Pics from a slashdot story very short while ago:
http://technology.newscientist.com/article/dn14172-fastestever-flashgun-captures-image-of-light-wave.html?DCMP=ILC-hmts&nsref=news1_head_dn14172
But it is easier to think of the quantized light in terms of... quanta! New particles, now with many new features and a money back guarantee!
Happy Independence Day!
And chimpanzees don't get termites, spit-covered sticks do.
Technology is as much a part of humanity as wings are of birds.
This has always bugged me; how in the heck do you quantize geometry like |x>?
|x> isn't geometry, it's a position variable. Geometry is described by a metric (or a connection), i.e., a tensor field. Simple perturbative quantization of a rank-2 tensor (the graviton field) doesn't work, but one can hope to try more subtle approaches. In the quantum geometry of loop quantum gravity, for instance, you represent a spatial eigenstate as a spin network, whose edges carry quanta of area and whose vertices carry quanta of volume.
I was under the impression there wasn't a good way to do that without losing isotropy.
That's the problem that many straightforward discrete approaches run into (e.g., lattice quantum gravity). If you break up space into a regular grid, then doesn't it have preferred directions? That's one reason why people look at things like random triangulations, random networks, etc.; you can hope that their small-scale structure is smeared out isotropically in the classical limit.
Moreover, wouldn't that screw up the coordinate transforms that we use to talk about some of the only analytically solvable systems in quantum, like the two-body central force problem?
Why?
Moreover, given that momentum and position are Fourier conjugates, does that quantize momentum as well?
Momentum is already quantized in ordinary quantum mechanics, at least for bound systems.
I guess if I can accept a continuous basis for position states I should have no problem with a countably infinite one, but it still confuses me. :-)
Quantum gravity is more subtle than merely making space into a countable lattice. And note that even in that case, if geometry really is quantum mechanical, a classical spatial state would probably look like an infinite superposition of different discrete lattices, not any single one.
Finally, (and this shows I haven't gotten very far in quantum), I'm troubled by the asymmetry between position and time in the formalism I learned, that is, position is a state, but time is merely a parameter. To be consistent with relativity, do you need to make time a state as well? How does that change \hat{U}(t)?
There isn't a "time operator" in string theory or loop quantum gravity, either. Even in quantum field theory (quantum mechanics coupled to special relativity), you don't have one. The theory still works.