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Initial Tests Fail To Find Gravitational Waves
eldavojohn writes that though gravitational waves are "predicted to exist by Einstein's Theory of General Relativity, the initial tests run by the Laser Interferometer Gravitational-Wave Observatory Scientific Collaboration (LIGO) failed to find anything. It doesn't disprove their existence although it does rule out a subset of string theory. From the article, 'For example, some models predict the existence of cosmic strings, which are loops in space-time that may have formed in the early universe and gotten stretched to large scales along with the expansion of the universe. These objects are thought to produce bursts of gravitational waves as they oscillate. Since no large-amplitude gravitational waves were found, cosmic strings, if they exist at all, must be smaller than some models predict.' The scientists working in Washington and Louisiana (in tandem to rule out flukes) will now move on to Advanced LIGO which will analyze a volume of space 1,000 times larger. If they don't find any gravitational waves in that experiment, the results will be more than unsettling to many theorists."
1. find contradiction in model
2. modify model slightly for exceptions
3. ??????
4. PROFIT!!!
An experiment is only a failure if you don't learn anything from it.
> The worst, that could happen for a physicist, would be that the observations could be explained with GR.
This kind of (extremely common) remarks strike me as frivolous. It is one thing to say that physicists enjoy being disproved, because this shows the length of the road ahead; it is another thing to say that physicists would hate to attain knowledge in one particular area or other. Science is in the business of securing truths, not in the business of idly advancing ever-refutable theories.
More like a cycle... observe, theorise, observe to check results, refine theory.
In this case, this is exactly what's happened - the observations looks like they may not fit the theory perfectly - hence, once that's been double-checked, go back and revise the theory and try to find out why.
If you don't test the theory, it's worthless. And if you posit a theory, only observation will definitively "prove" it. Science is about positing theories, observing results, and if they fit the theory - WONDERFUL... you just "predicted" part of the universe that nobody has before.
Unless horses get so expensive and building carts so cheap you'd rather prepare a thouosand different carts just to be absolutely sure of which kind of horse you're going to invest all your effort trying to find.
Not really. String theory is based on observations like any theory. You can observe things, see that it lines up with your theory, and you can falsify string theory. The problem with string theory, and the reason why people complain about it, is that most of its observations are also true of the boring old theories we have right now or true of other variations of string theory. People get a little annoyed when you come up with a dozen contradictory string theories and according to all known observations they could all be true and no one can figure out a way to disprove any of them shorting of lighting off a big bang.
Thats half-way there. Observe, then theorise, then make a prediction, and test that. The problem is that we have General Relativity and Quantum Mechanics, and both describe their own domains very well (the very large and very small, respectively) - but we have no way of combining the two into a single, unified theory.
String theory in its various permutations could be (partial) theoretical solutions to this, but coming up with testable predictions of such theories (such as large-amplitude gravitational waves) is horrendously tricky. Indeed, some theories are pretty much untestable by definition - many string theories have been considered to come into this category.
So we have our observation (GR and QM both work well, but are hard to unify), we have many predictions (string theories, etc), and now we have a test of many such theories in the form of this experiment.
"Observe then theorise" is all well and good, but when you can't you can test predictions of your theory, its not worth much.
Whilst scientists, being human, sometimes form attachments to a particular theory, the failure to find predicted gravity waves can only possibly be good for physics. It is also an exciting time for physicists; failures of existing theories to explain observations provide the kind of mystery a scientist can make a name for himself or herself by solving.
If we can put a man on the moon, why can't we shoot people for Apollo-related non-sequiturs?
That's the wrong way to look at it, when you fail to detect something that SHOULD have been detected using what you used, that means that things just actually aren't quite as you expected them to be. Sure there still may be some be gravitational waves, but this proves that they're nothing like we thought/nowhere as strong, if they exist at all.
You just got troll'd!
Now maybe the string theorists, such as Michio Kaku, will spend a little more time back at the drawing board and a little less time pretending to be Carl Sagan crossed with Alan Alda.
I doubt it. There is no such thing as "String theory". It should be more accurately called "String Theories". It's like a multi-headed hydra that lives forever. Falsify one part of it and 3 other theories pop up to replace it.
The only thing that can really kill String Theories is a experimentally verified competing theory that's unifies quantum mechanics and general relativity. Kill the body and the head will die.
AccountKiller
Pretty much certain? Yes, a lot of observations have fit the theory of gravitational waves, but this one in particular went against it. The observation method may be flawed in some way, but it COULD mean that the other observed effects are actually attributable to something else. Whether flawed or not, this observation did not disprove or prove the existence and/or nature of gravitational waves. It only served to potentially better define them.
Even if science were to come to the conclusion that some theologians were right all the time (it's completely impossible that all of them are right, because they contradict each other), it would still be a great achievement, because the theologians only have their faith, while the scientists would in that case have scientific proof. Or, to remain in the picture, while the theologists have been brought to the peak, and just had to believe it's the peak they were told it is, the scientists know the way to the peak and can therefore be completely certain of being on the right one. And BTW, even for the theologians sitting on that peak it would be great news, because they then would finally have a good argument that they got to the right peak, and the other theologians sitting on the other peaks were wrong.
However, it is more likely that when the scientists get over the final rock (assuming there is one), the'll find no theologian there, because those all sit on those lower peaks where it is much easier to get to.
The Tao of math: The numbers you can count are not the real numbers.
The problem of "negative" results, is that maybe you didn't detect something because it's actually not there, or maybe you just did your experiment wrong. Differentiating the two is non-trivial.
You *are* aware that Dark Matter has been observed, right? Or did you just miss the announcement of the Bullet Cluster results (among others)? As for Dark Energy, that isn't really a theory, so much as an observation with no explanation. Specifically, the rate of expansion of the universe is increasing. This is a fact. *Why*, we don't know, so we just call it Dark Energy for now. It's a placeholder, nothing more.
So please, take your trolls and go back into your basement, as it's pretty clear you don't really know what you're talking about.
. Science is in the business of securing truths, not in the business of idly advancing ever-refutable theories.
I'm sorry, science is in the business of proving theories wrong. All current scientific theories are merely those that have yet to be proved wrong. They are extremely valuable in that they can be used to predict future behavior of the universe to a significant degree of confidence. However, scientific theories cannot be proven true, they can only be proven false.
The great weakness of science is that people have a tendency to view theories that have been around for a long time and not proven false to be true. All it really means is that they are reliable predictors of the behavior of the universe insofar as our technology allows us to observer the behavior of the universe. Sometimes this means that they are good theories that are very useful (say General Relativity), other times it merely means that our technology has not yet reached the point where we can reliably test any of the theory's predictions (say the various String Theories).
The truth is that all men having power ought to be mistrusted. James Madison
Of course Einstein was wrong.
He was, at best, as right as any human could have been given the evidence available at the time. If he was as true a scientist as the world portrays him, then he expected to have his model refined over time as new evidence comes to light, eventually being completely replaced by something much more accurate.
Whatever new theory we build based on this new evidence will also be wrong, for the exact same reasons.
But it will be right enough to be useful as a stepping-stone to an even righter theory. That is how science works, and that is also why find science zealots to be even more annoying than religious zealots...science zealots have accepted as absolute truth a model that is just a stepping-stone, in direct contradiction of the very methods that they proclaim to be the ultimate determiners of truth.
it's a particle that waves from a float in a parade
How does *failing* to find the thing which was predicted to exist by Einstein, prove Einstein right? Granted, they weren't *expecting* to see gravitational waves at this point, because they were only looking for waves which would have been at such a high magnitude that they weren't expected to exist *except by string theorists* because of part of string theory. So, that part of string theory was *dis-proved*, but Einstein's theory has not yet been proved correct (though they expect it will be 'soon' when they start looking for smaller magnitude waves).
Anyhow, what's wrong with proving that our ideas about the natural universe are either correct or incorrect (or somewhere in between, in some cases)? You know, one never knows all the applications of scientific knowledge until long after that knowledge is obtained. Perhaps spending all this money now to do this science today, will lay the groundwork for very useful applications in the future? Perhaps the knowledge gained from these observatories will help us figure out how to make fusion work economically, or help us develop more advanced spacecraft, or even more advanced terrestrial vehicles? Or help us detect the aliens which are spying on us with advanced cloaking devices but can't hide their G-waves (ok, that last is mostly a joke, but one never knows)?
Scientific knowledge is, in itself, largely useful - how much has our technology and economy, our health and standard of living, improved, because of scientific advances achieved in past centuries that are only now being put to great use?
and why do we think we can detect them this deep inside a Gravity well?
honestly, looking for something like that needs to be outside the gravity well of the sun.
There's a pebble on top of Mount Everest. Using my trusty ruler, I measure the pebble as being 1.3 inches tall.
"Aha!", says my colleague. "Now we know that the top of the pebble is exactly 6 miles, 1.3 inches high!"
"No, silly!", says my other colleague. "The only way that we can measure the height of the pebble precisely is by bringing it down to sea level! Being on a mountaintop confounds any precision measurement!"
Oddly enough, the pebble turns out to be 1.3 inches tall. A most remarkable coincidence, I'm sure.
~Idarubicin
Here's the part that I find interesting. The whole gravity/space-time curvature is merely an abstraction of gravity into a new dimension.
Ancient people's idea of gravity was simple. Stuff goes down.
Then people figured out that the earth's surface is curved, and "down" didn't work anymore. The new theory of gravity said that stuff moves toward other stuff, and the earth is a big blob of stuff that all our little stuff moves toward. Kinda simple, but you don't have the nice, straight, linear sort of system. You've got a radial one, and other planets and stars have their own gravity fields that pull stuff toward them, and it's a bit more complex.
So, with this notion of mass curving the surface of space/time in some higher dimension, we envision space/time as a sort of elastic surface. Mass sinks into the surface, and smaller mass will "roll" into the depression caused by the larger mass. Why does the "mass" roll downhill? Well, there's the kicker: this higher dimension apparently has its own sort of gravity, and, like the ancients' theory, it's nice and straight: it always goes down!
Alexander Peter Kristopeit bought his basement from his mommy for one dollar.
Well, there's simply no point outside of the black hole in the absolute future of any point inside the black hole. In other words: There's no way anything could go which leads outside the horizon. You'd need superluminal speed to escape, but gravitational waves only go at the speed of light (and everything else goes at most as far, too).
That's the "trick" of the event horizon: It's not exactly that a strong force keeps you from going out, it's just that there is no way out (at least no way you can follow).
The Tao of math: The numbers you can count are not the real numbers.