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LIGO Fails To Detect Gravity Waves
planckscale writes "Last weekend, LIGO (the Laser Interferometer Gravitational-Wave Observatory) did not detect gravitational radiation in association with a gamma ray burst (GRB). The non-detection was actually a valuable contribution, as it helped to distinguish between competing models for what powers GRBs. The detector is due to be upgraded this year for even more accurate measurements. The interferometer is constructed in such a way that it can detect a change in the lengths of the two arms relative to each other of less than a thousandth the diameter of an atomic nucleus."
This is another failiure in the long history of trying to detect gravity waves.
As a matter of interest what would be the consequences to modern physics if Gravity waves do not exist?
Choose your allies carefully, it is highly unlikely you will be held accountable for the actions of your enemies
That must be the most useless analogy ever.
The grass is always greener on the other side of the light cone.
LIGO Succeeds in Detecting No Gravity Waves
"...of less than a thousandth the diameter of an atomic nucleus."
Would that be a hydrogen nucleus... a uranium nucleus? Please be more specific.
"I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
Failed to detect. The theory said something should be there, but at what relitive strenght? How much closer (Newtonionan) object be to have to eminate a wave that can be measured. They are looking on the order of a thousanths of a diameter of a neculus, over the length of 4Km.
..."
Is Mickelson Morley repeathing itself?
"The Mickelson-Morley Experiment failed to recognize that the round trip regardless of the direction would be the same and yet at the same time we know
Couldnt we just look at their data? Did a large event happen when they were looking at light beams? We just repeated their experment to an extrodinary accuracy.
I'll spell it out for you. This is not a failure of gravitational wave detection technology.
What you apparently do not understand is that this device can detect gravitational waves. However, it did not detect gravitational waves that correlated with a gamma wave burst originating in Andromeda. Normally such bursts arise from well known phenomena, such as a collision of black holes. But in this case, the collision could not have been from one of these well known phenomena.
What the article suffers from is bad writing. It should have been put in the positive--something like "the gamma-ray burst originated from a novel mechanism". Now, because astrophysicists can not account for the burst, they must go back and (1) study other similar phenomena and/or (2) revise astrophysical theory to explain the heretofore inexplicable gamma ray burst. Why is this burst inexplicable at this point? Because they did not detect gravitational waves that correlated with the burst.
Just callin' it like I see it.
Yeah, imagine somebody trying to use this sort of argument to defend a theory with political ramifications...
"... fails to detect Global Warming, but that's a valuable contribution anyway, as it helped to distinguish between competing models for what causes GW"
The head would be still alive flying in the air looking at the rest of the body being ripped into smaller and smaller pieces...
In Soviet Washington the swamp drains you.
Yes Neo, there is no gravity.
If you mod this up, your slashdot background will turn into a beautiful sunset!
They're little plastic blocks that kids build things with. Granted, you can make things like the Millenium Falcon with them but it can't actually fly.
Oh wait, you said LIGO, nevermind.
Summation 2
There is no gravity - Earth sucks!
In Murphy We Turst
1) General Relativity as formulated by Einstein (and a lot of other similar derivates - are there many?) would be in serious doubt. An exam question I had was take GR and show gravity waves exist - you basically show how the wave equation falls out of the formulas and these things carry momentum out of a system.
2) You then need to explain stuff such as Mercury's orbit precession and observed effects of double Neutron stars slowing down - the FSM stirring his planetary meatball lunch slower?
The Singularity is closer than you think
Quant
Your analogy falls apart before it even gets out of the gate.
First of all, we can detect global warming. The average temperature of the earth is rising. We have an accurate device for this: a bunch of thermometers all calibrated and sitting all over the world. We also have an accurate device for measuring gravitational waves. Both work fine.
Now, if you had said, "failure to detect elevation of carbon dioxide levels can not account for global warming", then your analogy might hold (despite the fact that CO2 levels do seem to be rising). I.e. the proper analogy would be "the absence of an observation means we don't understand a particular phenomenon".
Just callin' it like I see it.
Does it detect any gravitational wave at all? According to this wikipedia article, "... gravitational radiation has not yet been directly detected". I assume this means that no instrument can directly detect gravitational waves at all.
As far as I understand from the wikipedia article, they have deduced the existence of gravitational waves by the orbitals drawing closer of large rotating binary starts, but no instrument has ever detected any gravitational wave.
Please correct me if I am wrong - some links might help.
The non-detection was actually a valuable contribution, as it helped to distinguish between competing models for what powers GRBs.
Alternately, since no one can really say where gravity itself comes from, the concept behind LIGO could simply fail to account for how gravity really works.
Who can say that the same shortening of one side compared to the other doesn't affect the speed of light proportionately to the change in length? In that case, we could just as well have a black hole buzz our solar system and LIGO would hapilly report nothing of interest.
I 100% support science research, especially into some of the "real" unsolved problems such as the nature of gravity itself; but I would call this simply "bad" science - You can't use one poorly-understood phenomenon to explore another.
Actually, I don't think the article is saying that any rethinking of GRBs needs to be done here. The non-detection just proves the burst was from a lot farther than the Andromeda galaxy. That's a good thing, and in-line with some theories if I'm not mistaken. Last I'd read, these bursts can be so violent that they might kill all life forms in the galaxy where they occur. We really don't want them to be common enough to ever happen in our neck of the woods.
Beer is proof that God loves us, and wants us to be happy.
Actually, this result isn't as exiting as that. All they've shown is that the burst wasn't colliding black holes in M31 (Andromeda). It's still entirely possible that it was colliding black holes in a more distant galaxy along the same line of sight as M31.
licet differant, aequabitur
Any instrument needs to be calibrated before it can be used for detection. Which means that it has to detect gravitational waves *directly* on some event that is known to produce gravity waves. Apparently LIGO has not been able to detect *any* waves directly until now. Until it does that I think the grandparents question (If the gravity waves exist at all) holds good. Since LIGO has not been able to detect any waves, I do not understand how they can claim tha non-detection is a major event.
~561
I mean - I admit to being ignorant, but has there ever been a gravity wave detected?
Just asking.
Gravity Waves, meet Bigfoot, and the Loch Ness Monster and flying saucers and santa claus..
Ain't no such thing.
This is my sig.
As predicted, the bites are already being ripped out of my flesh...
In Soviet Washington the swamp drains you.
I thought the only "accurate" measurement of gravity was our observation of mass attracting mass. I didn't think that we'd actually discovered what "it" is yet, however. Without knowing what you're measuring, it's pretty hard to be accurate.
Isn't this other device completely theoretical thereby negating any claims of accuracy? Although I have to agree the analogy was terrible.
From the LIGO home page:
Just callin' it like I see it.
For all the people arguing over whether or not this is a failure of LIGO or not...it doesn't really say much at all. Initial LIGO (which is currently running) is more of a proof of concept sold as a viable project. But if you look at the expected rates of detection, the absolute high end for all binary sources is less than one event/year. The low end is between 4 events every 10000 years and 4 events every 100 years. The other source types are not any better.
This article basically says that because LIGO is known to not be sensitive enough to measure past a certain distance from Earth (which encompasses the Andromeda galaxy, in whose direction this burst occurred) and because no detection was seen, the burst was not caused from a source in the Andromeda Galaxy.
I suppose that after spending all this money its not a bad thing that LIGO can actually produce some useful results (though I doubt they were amazingly useful). Advanced LIGO should be able to do the job - but not for another 5-6 years. At that point, the minimum event rate is supposed to be around 1/year and we should finally get some sort of positive detection.
Personally I'm hoping Advanced LIGO does work, because otherwise all this money will have gone to waste and the field of gravitational wave astronomy will be even more damaged than it already is. The thing is, many people in astronomy who are not affiliated with LIGO are not excited by it. Maybe that interest will be rekindled when Adv LIGO actually works, since right now its more of an engineering problem than an astronomy or physics problem. More people are interested in LISA which (if it ever launches) should have many more interesting sources. Its amusing seeing LIGO people try to point out the flaws of LISA while trying to explain why LIGO doesn't work, but then maybe I'm biased since I am working on LISA (though I have worked on LIGO in the past).
Perhaps the LISA (NASA/ESA) project will have more luck (2015+).
and merely an incremental increase in knowledge. It either means that gravity waves are either smaller than "1/1000 of the diameter of a nucleus" (whatever that means) which would require a re-write of the theory because they were predicted to be large enough to detect or LIGO doesn't work which would require a re-write of the theory of gravity because according to that theory LIGO should detect gravity waves. It's a nice result but nothing definitive.
At the risk of opening up some sensitive old wounds here, if you had more than one of these...
would they be called LIGOs?
"Accuracy" does not refer to a technique but rather the quality of its product. Here, gravitational waves are probably not exactly what you imagine, but take an operational definition from the function of interferometers like LIGO. This device can be calibrated against a known source of measurement, and so estimates of accuracy comes from calibrating to said standard source.
Just callin' it like I see it.
Nononono... the standard "really tiny" analogy in popular media is "fraction of a human hair", e.g. "one thousands of the width of a human hair".
(completely disregarding that the width of human hair varies by at least an order of magnitude from person to person).
I looked at the Wikipedia article about LIGO and noticed this interesting question in the discussion. No one has answered it there. Apparently it's from some forum somewhere. Maybe someone here can explain the solution to this "conundrum" for me?
I'd be fascinated to see what's wrong with the reasoning here!
Ok - I accept your analogy of the DNA sequencing to explain the usage of "indirect". What I'm not sure is whether the authors of the wikipedia article intended to use the word that way.
Let's forget wikipedia for a second. Let me ask:
1. Has a man-made grativational wave been detected by LIGO (or any other gravitational wave instrument)? If so, I'd appreciate links to authoritative sources.
2. Has a natural event which has been corroborated by other sources been detected by LIGO (or any other gravitational wave instrument)?
Both the above tests have are true for DNA sequencing - man made and natural mutations can be detected "indirectly". If neither of the two conditions hold true for LIGO, then how do we know that it even detects gravitational waves?
Ofcourse, if my question appears ignorant - please understand that I'm a general slashdot reader and not a physicist. I'd appreciate your effort in helping me understand.
Not only does it mean we've done our job, it's also a whole lot of fun. Suddenly there's a whole new theory (or even better, lack of one) to test. Lots of new experiments to do. More hours to spend in basement labs...
ID'ers just don't know the fun they're missing.
That's strange coz I have to say I did feel a little lighter on Saturday.
Genesis 1:32 And God typed
From the wiki GW and here : The gravitational wave has been indirectly shown to exist by showing that the evolution of orbit of the binary system is in precise agreement with the loss of energy predicted by gravitational waves. Note that this was not done by LIGO. It was observed using convensional Radio telescopes. More over the LIGO is a *direct* detector of Gravitational waves. So I would like to know if LIGO has ever detected gravitational waves. If not the claim is questionable.
~561
Comment removed based on user account deletion
Terrorists can't threaten a country's freedom and democracy. Only lawmakers and voters can do that.
Something I don't understand from the article is that it seams they experiment supposes that both the X-way burst and the gravitational waves should come on time. But what if the gravitational waves had passed before the X-rays? Is there something in the physics theory that predicts this?
I'm not even a physicist, but I can recall someone arguing that gravity has the estrange property of been instantaneous. Is this is true, the even that generated the x-rays happened many years ago, right? why shouldn't we be able to detect any gravitational waves now?
What you apparently do not understand is that this device can detect gravitational waves.
That has never been demonstrated. For all we know, gravitational waves may simply not exist.
Yes. This is no failure in the dectection technology. People at LIGO have estimated what they can detect and what they cannot. This puts an upper bound in the energy of the gravitational waves that were emitted by the GRB source. If it emitted more they would have detected them. This shows GRBs theories have a long way to go. We dont even know the total intrinsic amount of energy of a GRB source. If the source radiates in a polar pattern (like a lighthouse) we only see a small fraction of the GRB sources that exists (when the beam is directed toward the earth), in this case the intrinsic amount of energy is much smaller. If the GRB radiates like a star in all directions the intrinsic amount of energy is MUCH bigger. We can estimate the maximum size of the source bases in the timing of the event (if it has very fast variations it must be smaller because the information to coordinate this variation cannot propagate faster than light). But we dont know much more. This "failed" experiment is as important fot GRBs theory as the "failed" experiment in detecting the aether wind by Michelson and Morley was for the birth of Relativity. It shows we must review our theories. Airton da Fonseca Granero
Sorry, I kept saying X-rays in my previous post when I should had say gamma rays.
What are you talking about? My water drinking bird always makes waves when he takes a sip!
GR is only one of a large number of possible theories that all make similar predictions for the kinds of phenomena we have actually been able to observe. GR happens to be the one that was first written down, and as long as it worked, there has been no reason to consider any of the others.
I just happened to watch:
...today.
http://video.google.com/videoplay?docid=-3934388013805572309&q=bbc+horizon+death+star&total=2&start=0&num=10&so=0&type=search&plindex=0
The gravitational wave detector doesn't detect gravitational waves?
"Hooray, I'm useful. I'm having a wonderful time." --Dr. Zoidberg
They're using their grammar skills there.
Seriously, how can you trust CDE users ?
I did an internship at LIGO last year, and let me tell you, they're always trying to make it sound useful for things like this. I went to one talk where this guy basically said "LIGO is very useful because the lack of any signal means that there can't be huge mountains on rotating neutron stars.". WTF? Neutron stars are widely expected to be the most perfectly spherical objects in the universe. Why would they have huge mountains? Nobody knows, but LIGO definitely ruled it out too, and that's a good thing I guess...
Honestly, there's very little chance of seeing anything until Advanced LIGO is ready in a few years. Now, if Advanced LIGO doesn't see anything, that will be news.
Does anyone know how fast these gravity waves travel? Is it possible that the detection of the wave will happen "next week"? It seems that they are assuming the waves travel at light speed. What if they don't?
Layne
Neil is that you? Yeah yeah, it's me... Neil...
The argument is that since binary systems which include a neutron star steadily lose energy it must leave in the form of gravity waves.
Einstein predicted transverse gravitational waves. This post questions whether LIGO is capable of detecting transverse or only longitudinal waves. The poster also points out that two waves would be generated and says that the longitudinal waves cancel at large distances.
Only his tendency toward a dazed stupor prevented him from screaming aloud.
You make a very good point:
"The absence of an observation" is not logically equivalent to "The observation of an absence"
I believe the point isn't that they failed to make an observation (Absence of an observation) but rather that they made the observation, and didn't detect anything.
This [theoretically] would prove that given current hypotheses about gravitational waves, are either a) not accurate or b) not measurable with current equipment
I will not give in to the terrorists. I will not become fearful.
There have been no direct detections of gravitational waves so far. There have been indirect detections (most robustly with the various binary millisecond pulsars, whose orbits slowly decay due to their radiating energy away in gravitational waves), but no direct detections. However, this was not really seen as an issue, as gravitational wave searches before LIGO suffered from the problem that there were no known sources strong enough for them to detect with good probability. You have to start somewhere, and there is always the chance of either good luck, say a close supernova, or some unknown source that is stronger than expected, but I believe that this is the first actual event whose gravitational waves, by a reasonable model, had a chance of being detected with existing equipment. One such non-detection means nothing - maybe the Gamma Ray Burst occurred way behind the Andromeda Galaxy, for example. If this is consistently repeated, we will eventually conclude that there is something wrong with our physics or our astrophysics, but it is much too soon for that.
I'm not a physicist either, though I have heard we have detected gravity waves from two pulsar systems (where you have two giant masses orbiting each other creating very clear changes in gravity) as well as some theoretical black holes orbiting each other, of course proving that the black holes are there in the first place may be tricky :)
Does a geisha painted on a Japanese fan know she's wrinkled? IOW, it's a frame problem, like biting your own forehead.
``Tension, apprehension & dissension have begun!'' - Duffy Wyg&, in Alfred Bester's _The Demolished Man_
They could not find an anticipated ether-drag. Their result nicely dove-tailed with special relativity. However Einstein started from first principles and not their result.
Perhaps the gravity result suggests a replacement for general relativity.
... if alternatives to GR got some more attention.
http://www.plasmacosmology.net/spec.html
http://peswiki.com/index.php/PowerPedia:Tesla's_Dynamic_Theory_of_Gravity#Dynamic_theory_of_gravity
Personally I'm getting the feeling that we're getting more and more off-course with the dark energy, dark matter, 10 dimensional 'string thingy' theories.
Yes, I am saying that this is a feeling.. I'm not a(n) (astro)physicist... but somehow I have the idea that the universe just has to be more elegant than our currently collection of exotic and unwieldy theories.
All good programmers should be able to understand what I'm saying in the previous paragraph.
Many persons have implied that not detecting gravitational radiation will somehow invalidate General Relativity. Unless I am mistaken, every theory of gravitation that requires that
1. Forces due to massive bodies (gravity) to propagate at the speed of light, and
2. Energy to be conserved
must also have gravitational radiation. Information propagates at infinite speed in Newton's theory of gravity, so there is no gravitational radiation.
Why is it whenever I have mod points there are no interesting topics to use them on :(.
Anyway, the parent makes a very valid point.
What if gravity waves are actually slower (or, dare I say it, faster) than the speed of light, what happens to the General Relativity equations then?
Quantum Physics a.k.a. sub-molecular statistics
LIGO sucks, no... wait...
If it's that vibration sensitive, we ought to put it at a Lagrange point.
In other experiments; last week my current haircut failed to cause Angelina Jolie to sleep with me. This is not really a failure on my part, rather, this experiment helps greatly to distinguish what haircut worn by the opposite sex, if any, powers Angelina's sexual drive. Rather, this is incredible and amazing scientific progress!! Champagne for everybody!!
Can I have more funding, now?
Now that I think about it, I'm pretty sure everything I just said is completely wrong.
The General Theory of Relativity says they should move at the speed of light. They are simply warps in space-time that are caused events involving really big masses (like black holes colliding). They are basically changes in gravitational forces as very massive object move. A classical example is two black holes rotate around each other and approach and collide. The gravitational forces vibrate up and down in magnitude as the objects move towards and away from us. That is the wave we're trying to detect.
Gravitational waves *have* already been detected, but they have been detected *indirectly*
(e.g. from observing changes in the rotation of super-massive neutron stars).
The LIGO experiment endeavors to provide *direct* evidence for their existence because
in science such evidence is ultimately more satisfying, but it is not strictly necessary.
Once upon a time, for example, evidence for the existence of atoms was also indirect, being
inferred from the behavior of gasses and other phenomena like Brownian motion. It was only
much, much later that atoms were actually directly observed, via advanced microscopes, but
in the meantime the atomic theory was never called into serious question.
So even if LIGO and its successors fail, the indirect evidence in support of gravity
waves is still strong enough to fully support the concepts of general relativity.
Do you experience paranoid delusions often?
Hello? Of course they couldn't detect anything. Gravity is an observed illusion (in our frame of reference) caused by the curvature of space-time. Do these people honestly get grants for this nonsense?
I have no doubt that if gravity waves exist, LIGO will eventually pick one up. It's question of timing.
I visited one of the LIGO facilities once, it was fascinating. But I learned two things there about how sensitive it was:
(1) When my group and I came in, they showed us the real time data -- there was a gigantic spike in the middle of the screen. One technician pointed to it and said "That was from you guys rolling up to the facility, we knew when you were almost here.". I then got to hear complaints about all of the loggers in the area that interfere, a highway being close enough for big trucks passing to cause spikes, etc.
(2) While in the control room talking, the mirrors went out of alignment and you could hear an alarm. One of the scientists got on his computer and came back with the reason: "There's a small earthquake in Greenland, it should be over soon."
They told us of the plans to upgrade the facility. Most of it involved adding more shocks and counterweights and all to dampen the various effects we saw that day. They claimed it would be enough, and seeing as their first few test runs were almost right on the money, I'm sure they're correct. But I imagine a little bit of luck is involved as well: having some big cosmic event happen when there aren't a lot of truckers on the road or earthquakes, etc.
...Absence of proof != Proof of absence.
What's purple and commutes? An Abelian grape.
"LIGO Detects Absence Of Gravity Waves" would be more accurate.
"LIGO Establishes Absence Of Gravity Waves Above Its Detection Threshold From A GRB" would be more accurate yet but too long for a headline.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Then there is the problem of trying to detect any localised representation of a phenomena that in theory, warps all measuring devices in the same fashion - general relativity bends spacetime because we as humans have trouble understanding space can be non-cartesian.
We hold firmly that it is at the very least 3 dimensions plus time. General relativity is actually the application of philosophical principles to physics. Its claim is that the manifold of spacetime is governed by a limit to the nature of its self understanding - the application of spatial dimensions as a reference frame leads this principle to limit time itself within the framework - it has to be something like this within this framework in order to maintain causality, or more precisely, to sustain any kind of coherence in a universe that changes shape.
If, in our constructed spatial mapping of our universe, one could easily violate causality, matter may have a problem existing and may only exist as energy.
If you believe in matter and hence a universe that has a strong causality and you believe that the universe does change shape - or to put it another way, the universe is not an unchanging entity, then something akin to general relativity is the logical result.
So, I have a real problem with gravity waves imparting energy at all - these waves are an illusion of spacetime bending, not some force that is exerted. From a philosphical point of view, gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course.
Time, in the same sense, is also an illusion. the limit on the rate of causality in space I think is consistent because the question of causality is the same question regardless of spacetime.
Being a metaphysicist, I have real problems with the validity of string theory, so most of what I'm saying is not worth much to physics yet.
A gravity wave is, by definition, a phenomenon that causes certain effects. The LIGO device detects such effects. So the LIGO device can detect gravity waves. Whether or not gravity waves have been detected is completely irrelevant. If some kind of wave zips by LIGO and LIGO fails to detect it, then it can't be a gravity wave. And if gravity waves don't exist at all, then LIGO can never fail to detect one.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
But there is an otherwise successful theoretical framework that predicts how gravity waves (if they exist) would be detected and LIGO is the amongst the first generation of detectors designed to probe that prediction. Its called "doing science." The alternative is just making stuff up and hoping it works -- and that's not what LIGO is doing. To the degree that you can "know" anything associated with an otherwise very successful theoretical framework, I think one can say confidently that LIGO can detect gravity waves of a certain type and amplitude generated within a certain distance of the detector.
i\hbar\dot{\psi}=\hat{H}\psi
And from http://en.wikipedia.org/wiki/PSR_1913%2B16 :
The orbit has evolved since the binary system was initially discovered, in precise agreement with the loss of energy due to gravitational waves predicted by Einstein's General Theory of Relativity. I'm no physicist either but this seems to cover your question.Wow. This is the first time I've ever been modded "Flamebait". Apparently satire wasn't the mod's strong suit.
On a sidenote, it's an unusual psychological effect, that the more I think about my post being modded Flamebait, and the irrationality(in my opinion) of the moderator, the more I want to lower myself to that level, and lash out indiscriminately once I get mod points. I seriously hope that I don't give in to such an irrational reaction, and at the same time I open my mind to the possibility that perhaps it was something like this happening to the moderator that encouraged them to mod me as such.
Whew...a little too much OCD for this silliness...time to go alphabetize my receipts. Should I do it according to vendor, category of the goods, brand name, or specific product name...decisions, decisions...
Now that I think about it, I'm pretty sure everything I just said is completely wrong.
"The interferometer is constructed in such a way that it can detect a change in the lengths of the two arms relative to each other of less than a thousandth the diameter of an atomic nucleus."
Which atomic nucleus? The nucleus for hydrogen is far smaller than the nucleus for uranium.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Of course, this is as I said only accurate on the order of a percent. Gravitational waves could travel a little faster or slower than light, in principle. But odds are, they don't. For this experiment, a few percent change in speed could mean a big difference in time, considering the distance traveled. So ultimately you're right: experimental constraints don't pin down the speed well enough to ensure that the two events are simultaneous. But given the large amount of evidence supporting relativity, it's probably not a coincidence that the speed of gravitational waves is so close to that of light.
.....Normally such bursts arise from well known phenomena,.......
A well known way of generating x-rays and gamma rays is to accelerate fast moving charges, usually electrons. Instead black hole collisions, could it be that immense galactic electric fields accelerate huge quantities of free electrons to stupendous energies? These electric currents then give rise great magnetic fields which force the electrons to emit intense synchrotron radiation which we can detect? We routinely do this sort of thing at places like the Synchrotron Radiation Lab at Stanford. They can generate the most intense gamma radiation bursts made on Earth.
Maybe the fast moving electrons collide with an object, abruptly slowing them down like a target in a cosmic x-ray machine? Bremstrahlung effects like this would not leave any gravitational signature, since there are no large masses, such as black holes involved.
All theory is gray
This is another failiure in the long history of trying to detect gravity waves.
And I see lots of replies pointing out that gravity waves apparently do exist (usually citing the rotating binary star pair that are spiraling in at the rate predicted by general relativity).
Of course if gravity waves as predicted do exist and behave according to the predicted mechanism, I expect the physicists who designed this detector would have done it right and that it would detect them.
But that raises a question I have NOT seen answered:
Has this particular detector ever given an indication of actually detecting a gravity wave?
The negative result would IMHO be more significant if we knew that the detector was operating and actually had detected waves - or something - from other events.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
....The General Theory of Relativity says they should move at the speed of light......
If gravity is confined to the speed of light, the Sun should have lost its planets long ago. For example, simple Newtonian math tells us that the Sun and Jupiter "KNOW" about each other right NOW or in a very short amount amount of time, not 43 minutes later. the Earth and the Sun "feel" each other's gravity instantaneously, not with an eight minute delay. The sun and the center of our galaxy communicate by gravity without a many light year time delay. Otherwise, the galaxy would fly apart.
Matter and electromagnetic energy have a speed limit, but gravity either doesn't have a limit at all, or it is incredibly high. Gravity equations do not contain any time values, only mass and distance.
All theory is gray
Unfortunately, too many physicists aren't very familiar with the theory of information.
If one can state the one basic principle in that theory it is that to send or store information you have to spend energy, increasing the entropy in the universe. However, thermodynamics is a macroscopic phenomenon, at quantum dimensions all phenomena are reversible. In quantum dimensions one could say that time is bidirectional. Coincidentally or not, it seems that in quantum dimensions there is no limitation in speed, information can be transmitted instantly. And, what is more, there are experimental results confirming this.
I confess I'm not too confident on those proofs that information cannot be transfered faster than light. Until someone creates a theory that conciliates quantum mechanics with general relativity, I'm willing to believe anything. Maybe irreversible time is just an illusion created by the thermodynamic effects in our macroscopic brains...
About a century ago, it was a serious blow to the scientific theories of the time when all the experiments done to prove the existence of the "luminiferous aether" failed. Maybe gravitational waves are the 21st century aether.
In a way, I hope so. Physics has grown too routine, a new grand theory would be nice...
Newtonian gravitational equations. In that you are correct. But reality is Non-Newtonian. All Jupiter knows is what the Sun was doing 43 minutes ago. All we know is what the Sun was like 8 minutes ago. Relativity puts a speed limit not just on light but on any type of information transfer. Unless you want to throw out causality. Go read your Einstein again. Or even any introductory physics text on relativity. They explain it quite well. Or here, for anyone who likes small words, try this.
there is always the chance of good luck, say a close supernova
If it's too close, it's very bad luck!
That that is is that that that that is not is not.
They will not, if the sides are curved. The big question is how do you define a straight line. Einstein assumed that in a vacuum you don't have any line that's more perfect than a ray of light. However, gravitation bends light rays, this has been proven experimentally to a very high precision. Therefore, a triangle made by three light rays around a mass will not have its angles adding up to 180 degrees.
Of course, you can always postulate the existence of an immaterial straight line which is not affected by gravity. Using those theoretical lines space wouldn't be curved by gravity, but what good is that? You could never use those theoretical lines to do any measurement or to build anything in this universe, so you might as well assume that the true straight line is the straightest thing we have here in our universe, the rays of light.
...It is integral to the equations that model electromagnetic phenomenon.....True. It is however NOT integral to equations that describe gravity! There is no time value in them. This is false. Time most definitely appears in the Einstein field equations. The linearized version of them is almost identical to Maxwell's equations.
You are thinking of Newtonian gravity, in which gravity is instantaneous. This is not true of relativistic gravity, in which gravity propagates at the speed of light. Therefore, if someone turned on a gravity generator or suddenly removed a gravity shield, the effects of that should be instantaneous, or at least very fast over large distances. This is false, as can be proven from the Einstein field equations. See here. Until Mr. Roemer first measured the speed of light, it too was thought to be instantaneous. Maybe someday the speed of gravity will be measured. It has been, albeit indirectly. The 1993 Nobel Prize in physics was awarded for this work. It equals the speed of light, plus or minus a few percent experimental error. The sun and the center of our galaxy are in gravitational "touch" with each other NOW, not how they were thousands of light years ago. This too is false. See the paper I cited here.
> We can't really be certain about that until/unless they detect something. If waves aren't detected and the equipment is examined again and again and everything looks in working order, then at that point it'll start becoming clear that there are no gravity waves passing through. Obviously it could take a lot of work to do this, but if no waves are detected for long enough there would come a point where physicists would accept that the device is working.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Occasional downmods are unavoidable. If you aren't modded down occasionally, it means you're being far too careful.
The proper way to interpret mods is: Modded up? Great! My post was appreciated! Modded down? Sigh. Stupid mods. Move on.
Only persistent downmods are cause for concern.
As long as your posting is generally constructive and contributing, you can always afford to lose a couple of mod points now and then, because this has no important effect on your karma. The effect on your karma becomes important only if you're consistently misbehaving, which clearly you aren't doing.
So just keep making good posts, and don't worry about the occasional downmod. It really is unavoidable.
Terrorists can't threaten a country's freedom and democracy. Only lawmakers and voters can do that.
....But reality is Non-Newtonian.....
For the electromagnetic interaction, relativity has been experimentally shown, but gravity is still pretty much a mystery. We know that matter somehow gives rise to an acceleration we call gravity. There is no way to tell the difference between this acceleration due to gravity and the acceleration of matter by some means. There is no experiment you could do inside, if you were sealed into a closed rocket, to tell whether your cabin was being accelerated through space at 32ft/sec/sec or if that cabin was simply parked on the launch pad on earth.
We also know by experiment, that the gravitational interaction is some 36 orders of magnitude smaller than the electric interaction. Two neutron stars or black holes in close proximity, could have way more influence on each other and the radiation emitted, by way of the electric interactions between them, than by gravity.
Sure, the theory of relativity asserts that gravity is also subject to the speed of light, but that part of relativity has never been experimentally verified. Newtonian mechanics mandate that gravity ITSELF not be in any way be impacted by time. Only the ACCELERATION produced by gravity has a time value. Since the planets and galaxies don't move relative to each other at anywhere close to the speed of light, relativity doesn't enter into the picture here.
All theory is gray
I think that at some point it would be accepted that the device was probably working - which isn't quite the same thing!
For my part, I wouldn't want to draw any really significant conclusions without independent confirmation, i.e., at least one other apparatus of different design producing the same results.
Even if you're trying to save the planet from global warming, I told you not to switch everything off on fridays!
OK, yeah, it's funny... ABOUT THE FIRST TWO TIMES YOU HEAR IT. After about the fiftieth, though... not so funny - more like... pathetic.
That is all.
So either "we don't really know anything about grb's", or the device isn't useful for doing what it was built for - not sensitive enough for example.
Well, probably both. Astronomers never seem to stop being "surprised" by just about everything they "discover".
_
\\/ are accustomed' - First Lensman
Maybe I'm still stuck in picturing things in three dimensions but I can't see how you could possibly create a transverse gravitational wave. From what I understand a gravitational wave is a distortion in the warp in space time due to a massive object oscillating toward and away from you. This would result in a space-time that, as the wave hits, is alternating between flat/curved (or as LIGO would see it unstretched/stretched) (ok, curved and more curved for all you sticklers out there). This seems to me to be the definition of a longitudinal wave (ex definition). Whereas a transverse wave would require flexing perpendicular to the axis LIGO is looking at and therefore unmeasurable. I may be completely off my rocker, but I do know the definitions of transverse and longitudinal. (At least I hope I do. If not, I've been teaching my high school students incorrectly with the awesomely long slinky)
Looking forward to seeing where I'm wrong or right. Thanks.
Seriously, what history books have you been reading? You've got parts right. Gravity is indistinguishable from acceleration if you attempt to treat an accelerating body as an inertial reference frame. Yes, an imaginary force does appear if you do the coordinate substitution in this case (see any number of textbook, or, if you enjoy comedy this).
But to assert that the gravitational portions of relativity have never been shown experimentally is ignoring history. I point you towards the precession of Mercury's orbit and the first observation of gravitational lensing in 1919 (See the Story of Eddington and the Eclipse, laid out in many places and quite humorously here. And that's just the simple ones. It's called General Relativity.
Now, let's look at some of your errors here:
1)"Two neutron stars or black holes in close proximity, could have way more influence on each other and the radiation emitted, by way of the electric interactions between them, than by gravity."
Ok, true, given certain things. Even true about the radiation. Except for we're not talking about EM radiation in this context, we're talking about gravitational radiation, which shows no response to EM forces.
2)"Newtonian mechanics mandate that gravity ITSELF not be in any way be impacted by time. Only the ACCELERATION produced by gravity has a time value. Since the planets and galaxies don't move relative to each other at anywhere close to the speed of light, relativity doesn't enter into the picture here."
I'm not even sure where to begin here. Newton is wrong. Sorry to say it. I teach his laws every day in class, and he's wrong. He got damn close but his basic assumptions about the nature of reality are off. Space and time are not static. The force of gravity is only varies with time as the location and the mass creating the space-time curving effect that we see as gravity varies. So, if the object moves (like, oh, I don't know, a binary black hole system) the force we notice will vary. It takes time for the information that the force has changed to reach us. We don't notice instantly. That would mean information has traveled faster than light. Which is not possible.
Oh, and by the way, relativity does enter into this as General Relativity is a description of gravity.
Seriously, go read the first couple of sections ofThe Elegant Universe. And then go read a text book.
"So, I have a real problem with gravity waves imparting energy at all - these waves are an illusion of spacetime bending, not some force that is exerted. From a philosphical point of view, gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course."
I'm sorry, you're not allowed to "have a problem" with it unless you can show the error in the math. Relativity is not Einstein just practicing an "application of philosophic principles to physics." There's a reason he took a long time to go from Special Relativity to General Relativity. He had to go learn the math from Minkowski (I'm simplifying their relationship a bit). You can't do it correctly without the math. You can talk about it but once you hit abstract concepts like "Energy" you need to go to the math. You're not allowed to "have a problem" with a moving object having kinetic energy. That math defines it as so. Same thing in the gravity case.
I've said it before in this thread and I'll say it again. Go read a text book, then come back and talk to me.
Let me spell it out for you. You need to learn to fucking read you fucking asshat. How you got modded informative and the parent got modded redundant, when you guys said the exact same thing, and you took 10 times as many words to say it, is anybody's guess. But you need to drop your fucking attitude, and stop polluting slashdot with your filth, you retarded whore.
Meatspace has prepared me for the likelihood that some moderators will not appreciate the irony of my attention to detail on this subject. It just leaves more irony for me to enjoy.
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
AC's comments in the Parent Post are not complimentary, but they are true. Articles on wikipedia stay on wikipedia until somebody takes time from their life to challenge them. I agree with AC, that "trusting wikipedia to be accurate about something" is a "BIG MISTAKE." Although wikipedia provides an extremely valuable service, it is only useful as an introduction to topics, and in some cases as a referral to "authoritative" sources. It is, by design, not "authoritative" itself. AC didn't say "everybody who uses wikipedia is a lobotomized moron" or "wikipedia is completely useless; there is no 'correct' way to use it." Those would have been "trolling" comments.
He made a valid point. Down-modding about it won't help you.
PiSkyHi, Being a metaphysicist, I have real problems with the validity of string theory, so most of what I'm saying is not worth much to physics yet. Strike "yet" from that and replace "much" with "anything." You "have a real problem" with reality, not with the study of gravity waves. The "philosophical point of view" from which you pontificate that "gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course" is completely invalid. The descriptions from which you derive yours are summaries of mathematical descriptions and are verbally imperfect, especially in their completeness, without the math. You clearly don't understand the math or don't respect the facts. I don't care which. Go away, read a textbook or read your navel, it doesn't matter. No need to come back and talk to me.
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
I can most definitely have a problem with something before the math is applied. To quote Einstein:
"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."
I am trying to point out that there is a good reason for general relativity that is based in philosophy - inside any possible universe that contains matter and strong causality, the manifold must have constraints.
Regardless of what math you use within the manifold, having a limit on the speed of information itself, gives rise to strong causality (A implies B remains stable until C implies NOT(A) is true for example).
If the rate of information had not limit, causality would not be apparent and hence matter would not be discernible from energy.
Do you believe that srong causlity exists in our universe ? answering this question with math will not suffice.
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
I don't know if I can handle that much irony...
"If irony were made of strawberries we'd all be drinking a lot of smoothies right now."
Now that I think about it, I'm pretty sure everything I just said is completely wrong.
"gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course" is completely invalid.
Nice proof, why didn't I think of that ?
Verbally imperfect without the math ? please go away and work to your hearts content on math, just don't expect it apply to reality simply because your math is correct.
Don't respect the facts ?
I have put forward logic to do with any possible universe that contains causality - you can refute it, but it exists at a level before math and I have made it clear that math alone is not necessarily reality.
To do physics, one needs to generate theories that effectively model reality and can be tested. To generate models, one needs to rigorously determine if a model is self consistent before testing it. Then you can do some math.
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
> The model of gravity as deformations to space-time does not logically
> imply that "gravity is not a force, it is merely a product of
> observing a universe changing shape."
You pretty much said it there - deformations, changing shape. If gravity actually is the result of the necessity of something like general relativity, which is what I am trying show, then why expand theory in a different direction to say gravity is a force?, seems unnecessary, a bit like postulating another dimension to take care of the inadequacies of our current description.
The logic is there. How could it be possible to sustain a universe with causality without a constraint on the apparent speed of information ? its not possible. Why ? because I am claiming something similar to the anthropic principle, without the humans. I am saying that if you believe in this universe holding a high degree of stability, then it follows that if any point in space could be observed within equal time, it would fail to present causality because there is no order, no chain of events, no apparent reason to any observation. An event could well be tied to any other point in space, you couldn't possibly know which other event was the real cause of this event.
Logic comes before the math and binds it. Qualify logically, Quantify mathematically. If you use math to measure something unstable, you can even quantify how wrong you probably are.
I am concerned that people are becoming dismissive of general relativity when its clear many do not understand its ramifications.
I think many string theorists still think you can quantify time in the same way you quantify space. I think they missed the point - and if they don't know it, the more math they do, the harder it will be for them to change their mind about the reasons.
Investing too much in math alone will lead to more dramatic paradigm shifts.
A haircut powers Angelina's sexual drive? I thought a checkbook did.
Wikipedia has an illustrative animation and commentary. The commentary states that there is no motion in the direction of propagation, i.e. a transverse wave.
Only his tendency toward a dazed stupor prevented him from screaming aloud.
Of course I believe in causality. To an extent. You only have to look at simple beginner's quantum mechanics to know something ain't right. Oh, and please don't go to the hidden variable idea. It's been debunked rather well. You're straying from my argument. Again, you fall back on quotes and flowery prose.
The point of it all is that all of this falls back onto the mathematics used to describe reality. Abstract concepts like energy and force (especially field forces like gravity) can't be described properly using words. They need hard quantifiable numbers. Go take a couple of courses in Relativistic physics. And throw in a good Calculus course or four. Then maybe come back and try again. mumble mumble hippies mumble mumble
But, unless I'm misunderstanding what a gravity wave is there is no motion in the direction perpendicular to propagation. It's a stretch/squeeze (ok, stretch/more stretch) thing as space warps differently. If I'm looking at it right the wikipedia illustration is off as the circle warps not just in and out but up and down. I don't see why it should do that.
I wish I hadn't blown my mod points modding up actual informative articles in this thread. I'd rather see them go unmodded than see wrong claims marked "informative"
And this "Informative" post is wrong as well: relativity always applies when considering the speed of gravity, no matter how slow the motion or how weak the field (more here). And it is ridiculous to claim that relativity has been shown with respect to electromagnetism but not gravity, given all the experimental tests of GR (here).
At last we agree on something. There can be no doubt that causality has its own limits when considering quantum mechanics. Considering the apparent stability of this universe relative to our own existence though, it would be unwise to dismiss general relativity without acknowledging the implications of such stability on any possible spacetime manifold.
quotes and flowery prose ? hippies ?
what have you been smoking ? math ?
You want me to bring Godel in ?
I am glad you want to use math, just recognise its shortcomings in the realm of physics. We do need to keep re-thinking the definitions of energy and forces, our current math is not axiomatically sufficient to describe the consequences of combining the principles of general relativity and quantum mechanics.
I just don't want to see the baby thrown out with the bathwater - any new math that can help engineers deal with these principles must also encompass the principles, I look forward to it.
The logic I have shown is not flawed, just not often understood.
Please don't bother referring to math again. I have made my stance clear on how much math has to do with this problem.
Mathematics is a powerful creative tool, worth smoking - let me know when you feel like joining the rest of reality.
Ok, now you've just plain confused me. Where did I ever suggest the relativity was wrong? When did I ever say math is bad? It seems to me that's what I've been advocating the entire discussion here. What I'm arguing with is your dismissal of the very definitions of force and energy.
Now, the quantifiable formulas for each of these forces and energies are up for grabs as new relationships and new laws are formulated. But the definition of a force and the definition of energy are not. I was taking offense to your dismissal of gravity as 'not really a force' (you said something to that effect) and gravitational waves as not being energy bearing (also said by you), and the fact that your dismissal of these ideas through the use of some metaphysical argument.
When I first read about gravity waves, it made no sense to me that they should be energy bearing. I am aware that there is evidence to show that binary stars lose energy due to these waves - but I am not convinced yet.
The perceivable time difference between emitted pulses slowly decreasing suggests the system is losing energy, but I am not certain yet that its gravity waves causing this energy dissipation. At this stage the evidence for energy bearing is stronger than against.
To be honest, I think that if gravity waves are energy bearing, then we made need to reconsider gravity as a bending of all content in spacetime - the subtle changes in length must not apply to all content, otherwise no instrument would have any chance of detecting them.
Consider 2 points that according to general relativity, have a variable distance between them, when it varies, doesn't the frequency of light between these vary as well ? doesn't the detector of light vary as well ? if all content varies uniformly, how could there be any "detection" at all unless something broke the rule of spacetime bending ? do the nuclear forces feel the need to have their own definition of length that doesn't change ?
You can't just ignore the fact that the definition of force in relation to general relativistic gravity is questionable and ongoing.
Many are able to see the potential of interpreting gravity as the product of observing the universe changing shape. Time could very well be the product of a high degree of causality and stability in a changeable universe and not a dimension at all.
metaphysics is not a joke, if we are serious about combining quantum mechanics with general relativity, we will need to reassess derivations not just find new formulas - why ? because what we know so far of general relativity is that it makes a mockery of our current math with the manifold changing shape in accord with its matter distribution.
This problem could well be shown to be intractable.
Our best math so far only simulates classes of objects within relativistic space, so far only spacetime itself holds the real answers.
Consider 2 points that according to general relativity, have a variable distance between them, when it varies, doesn't the frequency of light between these vary as well ? doesn't the detector of light vary as well ? if all content varies uniformly, how could there be any "detection" at all unless something broke the rule of spacetime bending ? do the nuclear forces feel the need to have their own definition of length that doesn't change ?
I wrestled with this one too. After a little bit of research I think I have an answer for you. Yes, the distances would change and the frequency would change but the speed of light through the distance would not. Which would lead to it taking a shorter/longer amount of time for the light to travel the distance between the two masses. If I recall correctly that is the underlying basis for relativity. If you look at the LIGO fact sheet from the group doing this work they use this difference in time to look for phase changes in two originally in phase light rays.
Many are able to see the potential of interpreting gravity as the product of observing the universe changing shape. Time could very well be the product of a high degree of causality and stability in a changeable universe and not a dimension at all. Sounds intriguing. Please elaborate as I haven't heard of this one.
I'm confused by your point about the debate on the definition of force. I've never heard that one. Can you point me to some references? Everything I've seen shows it as just the negative derivative of potential energy.
This is a failure neither of LIGO nor of theories of GRBs. The error box on the sky position of GRB070201 included one of the arms of Andromeda, but it also included a lot of sky behind Andromeda. Possible explanations for not seeing GWs associated with the burst include 1) the source, whatever it was, was not in Andromeda, but farther away, or 2) the source of the GRB was in Andromeda, but it was produced by something other than a compact binary merger. This would also not be inexplicable; the abstract of the article submitted to the Astrophysical Journal says "This upper limit does not exclude current models of SGRs [soft gamma-ray repeaters] at the M31 distance." What is excluded, at >99% confidence, is a neutron star/neutron star or black hole/neutron star merger in M31 (Andromeda).
.......we're talking about gravitational radiation.......
Can you point me to an actual experiment or observation of such radiation being detected? I'm not talking about somebody's THEORY, even Einstein's, but real scientific measurements here. In the original article it was stated that no gravity waves were detected with a very advanced instrument built especially for this purpose. Not detecting something is often just as important and finding it. The Aether's existence, as postulated back then was disproved by showing its absence.
Measurements and observations must ALWAYS take precedence over *any* theory, no matter how widely held it is or how famous its originators are. Dark matter/energy are another theoretical construct that have never been observed. The Oort cloud as the source of comets is another theoretical fiction that has never been shown to exist. The red shift is well observed and measured, but its cause being theorized as the doppler effect is pure assumption, (belief) just as much as any belief of a religion.
For example, we know by experiment and every day practice, that gamma and x-rays are produced by the acceleration of charges. If the theorized bodies, such as neutron stars and other objects are NOT electrically neutral toward each other, then enormous electric fields could serve to accelerate charged particles, usually electrons, to immense energies. We also know by every day experiments that moving electric charges produce magnetic fields. We also observe that these magnetic fields tend to force these charges to NOT travel in a straight line, thereby releasing synchrotron radiation, ie. gamma rays. These fields also tend to focus these charged currents into narrow beams. You can sometimes see this effect in a neon sign. We also commonly observe that when fast moving charged particles suddenly slam into an obstacle they also produce large quantities of radiation. Could it be that such well known, researched mechanisms might be responsible for these radiation outbursts we observe? Could it be that gravity is not in the least involved in this and that's why we have not observed gravitational waves from this or any other source? If bodies, such as the sun and the planets are not electrically neutral, and there is evidence (solar wind) that they are not, the electric fields and currents around and between them would certainly affect electromagnetic radiation passing through those fields and currents. Thus what is thought to be "gravitational lensing" deflecting electromagnetic radiation, could also be caused by the electric and magnetic fields surrounding highly charged objects, such as the sun, such as in Eddington's observation during the solar eclipse. He observed a deflection of light, but he INTERPRETED that observation as being due to gravity.
(...information has traveled faster than light. Which is not possible....)
Information and its carrier are distinct. If there is a carrier that can go faster than the speed of light, then so can information. It is theorized by no one less that Einstein that gravity too is subject to the speed limit of light. However this has not been EXPERIMENTALLY or observationally verified. Gravity is a very weak force, quite distinct from the other forces of matter. It arises out a still mysterious property of matter we call mass. Until we know what it is about matter that causes it to have this thing we call mass, gravity will not be understood. We do know that both gravity and the electric interaction are long range forces and therefore can and do affect the universe as a whole.
It is NOT science when one makes up theories that have no basis in actual repeated observation or experiment. Einstein's theories have many aspects. Some of these aspects have been experimentally verified to many decimal places of accuracy. Others, such has some of his ideas about gravity have not, at least as far as I know. He did not like quantum science all that much, until experimental evidence piled up. Questioning Einstein is akin to heresy in religion, but I am under the impression that science is different, that it is based on observation and experiments. Maybe I am wrong about that.
All theory is gray
I have thought about the 2 point problem - I believe its possible that its spacetime that is changing as the gravitational waves pass through, not just space. I think it may have something to with the special relativistic effects of compressing/decompressing a point in spacetime at the speed of light. I suspect the clocks change according to the spatial acceleration - even changes in frequency would not be detected because any measurement of time is also variable with gravitational waves.
If that is correct, gravitional waves are a phenomenon that could only be observed as a kind of large scale lens illusion. Its possible it would avoid detection on a localised scale and also possible that there is no energy exchange of gravity into matter like suggested shearing effects.
I have no proof of this at this stage, but its food for thought, I also think that gravity as a force maybe the hardest concept to let go of when considering the general relativistic realm. Its possible that gravity is just a consequence of the real shape of reality and not a force. We don't know the real shape of reality yet.
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
Because you're supposed to be looking at it along the axis of propagation. The horizontal distortions are interspersed with vertical distortions similarly to the way electric and magnetic field strength maxima follow each other in an electromagnetic wave.
Only his tendency toward a dazed stupor prevented him from screaming aloud.
Ahh those Roman savages, you obviously know me too well.
It is clear that you haven't a clue what I'm talking about when I draw an analogy with the anthropic principle. I don't care if you understand and dismiss the principle, you've missed my analogy by several light years. Have you given string theory a good go ? being verifiably consistent with reality is of little importance when you can add more complexity to match observations.
One ring to rule them all ?
Did you actually read that paragraph at all ? what's your problem ? having a little difficulty with syllogisms ? until you deconstruct it, you have zero credibility to dismiss it, don't make me repeat that.
I'm not going to do your research for you, I tried to show why there the apparent strength of causality as shown by the stability of matter in this universe places constraints any spacetime manifold definition. It doesn't take much to state it and show that its important.
So, anyone wanting to find an alternative to general relativity should keep it in mind.
Logic comes before the math and binds it. Qualify logically, Quantify mathematically. You first. Start with this: I am concerned that people are becoming dismissive of general relativity when it's clear many do not understand its ramifications.
Which people, and which of the ramifications of general relativity do you claim we do not understand?
All 19 hijackers were known terrorists 09-10-2001. Lack of FBI intelligence does not justify warrantless wiretaps..
Stop. Please. Just stop. You're making real physicists cry.
It is NOT science when one makes up theories that have no basis in actual repeated observation or experiment. Einstein's theories have many aspects. Some of these aspects have been experimentally verified to many decimal places of accuracy. Others, such has some of his ideas about gravity have not, at least as far as I know. He did not like quantum science all that much, until experimental evidence piled up. Questioning Einstein is akin to heresy in religion, but I am under the impression that science is different, that it is based on observation and experiments. Maybe I am wrong about that.
You're allowed to question Einstein. But do it correctly. You can't say "Well, this observation confirms this part of his theory so I'll believe that, but you have no evidence I should believe a different part of the same theory." It doesn't work like that. If one part is shown to be consistent with data then that says that there may very well be something behind the other parts. They're all part and parcel. Science does not accept a line-item veto. If one properly constructed conclusion is disproven then the whole theory is called into question. And so, saying that several pieces of Einstein's theory have been shown accurate to umpteen decimal places lends a hell of a lot of credibility to the rest. They're all part of the same theory.
.....They're all part of the same theory......
They may all be part of the same theory, but the gravitational interaction and the electric interaction are VERY different. Applying the same rules, limitations and principles to them both is clearly a step of faith, not science. We don't KNOW, by actual measurement and observation, any more about gravity today than what Newton discovered a good while ago. The basic rules by which planets and spaceships move were established by him and are still used, essentially unchanged. Einstein and his theories are not used at all when calculating the path of a rocket to the Moon or Mars. Einstein developed theories, parts of which are well verified by experiment and observations. Those verified theories ALL involve the electric interaction. We are very familiar with the gravity and time, but both of these are still mostly mysterious to us as to their fundamental nature. By comparison, in the study of the nature of the electric interaction, both practically and theoretically, we are much further along.
So much effort is expended today in trying to make the data fit existing theory, rather than looking to fit the theory to the data. Cosmologists are having an ever harder time to make the what appears to be strange data fit existing theories. This is what religion does. They have a dogma which they will defend to the death, sometimes literally putting to death or persecuting people like Kepler and Copernicus and others who come up with observations that don't fit the 'accepted" data of the day. I had always thought that true scientists are above that sort of behavior, preferring to seek truth, regardless if that truth might demolish a PhD. thesis or even a whole life's work developing a theory. Maybe I'm naive about this.
All theory is gray
Yes, I get it. Did you read the linked articles? Can you show me the error?
Only his tendency toward a dazed stupor prevented him from screaming aloud.
2. The fact that radiating bodies are "embedded in the universe" does not mean that they are always in the near field. They pass into the far field when their distance is large compared to the system size and wavelength, which is certainly the case for interstellar distances.
3. Transverse waves from two co-orbiting bodies do not cancel in the far field. I can't explain what's wrong with his reasoning because he doesn't give any; he just asserts it. He does give reasoning for which longitudinal waves should cancel completely, which is doubly wrong because (a) there aren't any longitudinal waves to begin with and (b) he seems to think that the wavelength should be twice the diameter of the binary orbit, so that moving one diameter away corresponds to a 180 degree phase shift. This is not true. (The wavelength is proportional to the orbital period, not the orbital size.) Probably Ohanian and Ruffini have a derivation radiation from the binary source system as well, but you could also try Saulson's interferometer book.
4. Transverse waves, received vertically (the direction to which LIGO is sensitive), will in fact produce a stretching/compression of the local horizontal. They do not "tilt" or otherwise affect the local vertical. This is just thee definition of a "transverse wave".
By the way, responding to another post, Actually the main assumption on which GTR is built is that there is an unobserved fourth spatial dimension which accounts for gravitational effects (curvature). No, that is not an assumption of general relativity. GR refers to only the observable three space dimensions (and one time dimension). It is mathematically formulated in terms of intrinsic (Riemann) curvature only; it does not use the more familiar, but different concept of extrinsic curvature, which appeals higher space dimension(s) in which a surface should curve. Nowhere in the theory, or in Einstein's publications, will you find reference to a fourth spatial dimension.