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Fraser
2006-Apr-19, 06:49 PM
SUMMARY: As part of his general theory of relativity, Einstein predicted that mass should emit gravity waves. They'll be weak, though, so it would take very massive objects to produce waves detectable here on Earth. One experiment working towards their detection is the Laser Interferometer Gravitational-Wave Observatory (or LIGO). It should be able to detect the most powerful gravity waves as they pass through the Earth. And a space-based observatory planned for launch in 2015 called LISA should be stronger still.

View full article (http://www.universetoday.com/am/publish/eanna_flanagan_gravity.html)
What do you think about this story? post your comments below.

trinitree88
2006-Apr-19, 10:09 PM
SUMMARY: As part of his general theory of relativity, Einstein predicted that mass should emit gravity waves. They'll be weak, though, so it would take very massive objects to produce waves detectable here on Earth. One experiment working towards their detection is the Laser Interferometer Gravitational-Wave Observatory (or LIGO). It should be able to detect the most powerful gravity waves as they pass through the Earth. And a space-based observatory planned for launch in 2015 called LISA should be stronger still.

View full article (http://www.universetoday.com/am/publish/eanna_flanagan_gravity.html)
What do you think about this story? post your comments below.

As this is the Universe Today Forum, not the Universe ~ 19 years ago forum, I think it's nice the search for gravitational radiation has expanded in scope, and sensitivity. Best wishes to the experimentalists in their quest.

antoniseb
2006-Apr-20, 10:44 AM
I'm more confident than trinitree88 that we will observe these waves, but not so certain that I'd bet my head.

GOURDHEAD
2006-Apr-20, 12:40 PM
What is the imagined phenomenon we'd be looking for? How will our locality be modulated?

Eta C
2006-Apr-20, 12:41 PM
Well, I did bet a bottle of wine with the now banned Sparky/Soupdragon2 that we'd see direct evidence for gravity waves by 2012 or so. That's going to be a hard one to collect now.

Alfonso Guillen
2006-Apr-20, 02:46 PM
According General Relativity gravitational waves are ripples of spacetime but Einstein formulated only G11 and G22 oscillate and thus gravitational waves propagate in 4D. I has founded that also G00 oscillate. This is consequence of the energy density, T00, oscillation. Einstein died in 1955 and Hulse and Taylor in 1993 for Neutron binary stars found this phenomenon but that it was not formulated. Then gravitational waves propagate in 5D.

Jerry
2006-Apr-21, 02:56 PM
Well, I did bet a bottle of wine with the now banned Sparky/Soupdragon2 that we'd see direct evidence for gravity waves by 2012 or so. That's going to be a hard one to collect now.
I'll take some of that action...In fact I will go 1:2 on it...unless laying odds on the forum leads directly to banning...

The analysis of LIGO run 4 is now more than halfway complete, and run 5 is into it's 6th month of almost continuous data collection at the designed level of sensitivity. This is an outstanding technilogical achivement by any measure. If absolutely nothing shows up on run 5, or any data collected at this level of sensitivity through 2010, your odds of losing your bottle of wine go up significantly.

Minor caveate: I think we see gravity waves all the time; manifest as gamma rays, if I am right, so are you:)

Grand_Lunar
2006-Apr-21, 08:12 PM
Most fasinating.

I hope this project is successful. A former poster here (actually, on ATM) assertained gravity waves don't exist because we haven't detected them yet.

It would be gratifing to see him proven wrong once and for all.

Jerry
2008-Jan-08, 06:04 AM
http://www.ligo.caltech.edu/~ll_news/s5_news/s5article.htm

LIGO's Fifth Science Run Draws to a Close
with One Full Year of Triple Coincidence Data

This is an important milestone, but the announcement was rather low keyed. The data reduction will take a while.


Just as the Michelson Morley interferometer did in aether, LIGO has the potential of putting relativity back on the shelf...and force us to dust off the old books.


Whatever the result, LIGO is an incredible technical achievement.

Thanatos
2008-Jan-08, 08:03 AM
I'll take that bet. Binary neutron star orbital decays have already validated the model [Hulse, et al.]. Detecting gravitational waves is merely a technicality.

Jerry
2008-Jan-11, 05:54 AM
I'll take that bet. Binary neutron star orbital decays have already validated the model [Hulse, et al.]. Detecting gravitational waves is merely a technicality.
Binary Newtron star decay relies upon a number of assumptions that cannot be directly verified. (Remember if the theory is wrong, so may be the masses for the Neutron stars derived using the theory.)

At the same time of the Hulse analysis, contemperaries were predicting gravity waves would be detected at much lower sensitivities than current constraints. Weren't LIGO's scientists predicting science run 5 would have a reasonably high probability of detecting binary star mergers?

undidly
2008-Jan-15, 12:47 AM
Why don't gravity wave detectors get overloaded by the moon?.

Viewed from earth the moon goes around every 25 hours and the main tide is every 25 hours.Smaller tide halftime but that is a new thread.

Is the sea a huge gravity wave detector?.Could we infer the existence of the moon if it was NEVER seen(fog,clouds or no such thing as sight)?.I think so.

Jerry
2008-Jan-15, 05:42 AM
The period - the frequency of gravity waves LIGO is tuned for is of the order of Hertz to kilohertz - much lower than periodic effects of the moon. That said, they do have to filter for a multitude of low frequency events - such as rainfall, ocean waves and motor vehicles. Very challenging research.

minorwork
2008-Jan-15, 08:07 AM
GRB 07201. No detection. More sensitivity needed? This, my first post, is also my first experience with LIGO and it was in finding that GRB 07201 did not show on the run being performed when it occured. I've started probing for info that LIGO has detected gravity waves and can associate them with something. Only been at it an hour now and can't really put my finger on the associated events.

trinitree88
2008-Jan-15, 08:15 PM
Gravity waves were reported coincident with neutrino bursts from Supernova 1987a at the Rome and Maryland bar gravity wave detectors, and the Mont Blanc, IMB, Kamiokande, and Baksan Neutrino detectors at the Neutrino 88 conference at Tufts University, Medford, MA by Guido Pizzella, and were later published by same in Il Nuovo Cimento C, and several other journals. :dance: pete.

Jerry
2008-Jan-18, 03:03 AM
Those early reports of gravity wave detections of supernova 1987a were later retracted...gravity waves were also reported in the 1970's, but never verified. As the current generation of antenna are about a million times more sensitive than they were in the 70's, we can safely say the detections were artifacts. The LIGO team has not reported any detections. Science run five, which ended in November and collected a years worth of data, is still being analysed. To date, no reports of gravitational waves have been substantiated.

rtomes
2008-Jan-18, 10:28 AM
What frequency of gravitational waves that LIGO can detect? I looked for this and it seems that the limit is about 10 HZ and that some other instruments might go to 0.1 Hz. It is a pity that it doesn't go a bit further.

I predict that gravitational waves of frequencies .0058, .0029, .00020 and .00010 will be found when instruments can measure at these frequencies. This prediction is based on many cycles studies that show that periods of 3, 6, 80 and 160 minutes are found in many disciplines on Earth, in the Solar System and beyond the Solar System. I think that such frequencies must be universal wave phenomena.

I would like this prediction to be recorded here so that when the time comes to test this it can be shown that the study of cycles is a very useful way to learn more about the Universe compared to say spending billions of dollars banging particles together,

antoniseb
2008-Jan-18, 12:16 PM
I predict that gravitational waves of frequencies .0058, .0029, .00020 and .00010 will be found when instruments can measure at these frequencies.

For Gravitational waves of these frequencies, we'd need LISA like detectors configured across the Solar system, like at the Earth-Sun L1, L4, and L5 points, and similarly for Venus and Jupiter. I don't expect those to be built in my lifetime. Such waves would potentially be created by the merger of two supermassive black holes, but I don't imagine that the likely frequencies generated would have peaks at the values you've given here, but rather would be smoothly distributed across a broad range of frequencies in that general area.

LIGO could potentially detect Gravitational waves from the merger of a stellar mass black hole and a neutron star, or a pair of one or the other.

trinitree88
2008-Jan-18, 03:45 PM
Those early reports of gravity wave detections of supernova 1987a were later retracted...gravity waves were also reported in the 1970's, but never verified. As the current generation of antenna are about a million times more sensitive than they were in the 70's, we can safely say the detections were artifacts. The LIGO team has not reported any detections. Science run five, which ended in November and collected a years worth of data, is still being analysed. To date, no reports of gravitational waves have been substantiated.

Jerry. Not true. Some, but not all of the scientists involved in that claim retracted their statements. The majority did not and continued to publish the result multiple times in a number of different journals, conference proceedings, and papers. The sensitivity was just about at the theoretical threshold of the detectors as far as I recall, with a large but not insurmountable signal/noise ratio. I'm sticking to my guns here. A difference of opinion makes a horse race.... with all due respect.
A core collapse supernova is not spherically symmetric, (SN1987a), which means the center of mass moves, which means a G-wave MUST be generated, and it should occur stepwise, like the core collapse, and the neutrino emission. Coincident with massless neutrinos traveling at c.....the results on neutrino masses (Eta C..Particle Data Group) are still iffy in absentia of a matter path. Guns get a little closer here. pete

Jerry
2008-Jan-19, 06:43 PM
Ya, we need another close event to help nail this down. In the papers I read; it was clear that if the event was recorded at the level reported from certain stations, it should have been picked up at other stations, with an appropriate time delay between the devices. The recordings were never collaborated, so even though 'something' was measured in some places, it cannot be isolated from a very local artifact.

Today, the world-wide string of GWave detectors have extremely accurate time-stamping; so if another event occurs this close, we should not have any difficulting determining whether any signals we observe that are coincident with the event, are from the appropriate location in space, or not.

Squink
2008-Jan-20, 04:30 AM
GRB 07201. No detection. More sensitivity needed?GRB 070201
http://arxiv.org/abs/0711.1163

No plausible gravitational wave candidates were found within a 180 s long window around the time of GRB 070201. This result implies that a compact binary progenitor of GRB 070201, with masses in the range 1 M_sun < m_1 < 3 M_sun and 1 M_sun < m_2 < 40 M_sun, located in M31 is excluded at >99% confidence. Indeed, if GRB 070201 were caused by a binary neutron star merger, we find that D < 3.5 Mpc is excluded, assuming random inclination, at 90% confidence.

antoniseb
2008-Jan-20, 02:06 PM
Indeed, if GRB 070201 were caused by a binary neutron star merger, we find that D < 3.5 Mpc is excluded, assuming random inclination, at 90% confidence.
AND assuming that these waves travel at close enough to "C" that it arrives within a minute and a half of the gamma rays after a 10 million year trip.

Jerry
2008-Jan-22, 12:23 AM
...and assuming that gravitational waves propagate in the way theoriests expect, detectable by antenna that react to warps in spacetime; which of course assumes space can be warped.

90% confidence is an interesting number to place upon an experimental telescope concept that has never detected anything.

antoniseb
2008-Jan-22, 01:38 AM
90% confidence is an interesting number to place upon an experimental telescope concept that has never detected anything.

Yes, I agree, though I suppose there was an implied list of our caveats in the statement. Until we detect gravitational waves we will not know if we can detect them directly with Earthly equipment.

trinitree88
2008-Jan-23, 01:24 AM
Yes, I agree, though I suppose there was an implied list of our caveats in the statement. Until we detect gravitational waves we will not know if we can detect them directly with Earthly equipment.


Antoniseb. And had not the clock at the IMB proton decay experiment been set by somebody's wristwatch, but been on Universal Standard Time, the entire controversy with respect to whether or not the g-wave signals from SN1987a were coincident with the neutrino bursts in a fashion indicating appropriate time lapses for passage through the Earth,from the Large Magellanic Cloud, at Kamiokande, Mont Blanc, Baksan, and the Rome and Maryland bar g-wave detectors....but then they never expected Sanduleak 69 202 to "supe".... pete.


edit: It'd be interesting to see if the gentleman involved set his watch to a local radio station and whether an ancient tape would show if the station's "clock" was off by the appropriate delay that day...hmmm

Jerry
2008-Jan-23, 06:03 AM
Don't overlook that fact that gravitational wave antenna today are more than four orders of magnitude more sensitive than they were in 1987. That is a lot more space in which we have not detected anything.

minorwork
2008-Jan-23, 04:41 PM
Is a detection qualified by a neutrino burst, gamma ray burst, or other associated phenomena within a certain time period with a hit from the gravity detector? What I'm trying to determine is if a gravity wave detection hit has occurred without any other non gravity event.

idav
2008-Jan-23, 05:14 PM
SUMMARY: As part of his general theory of relativity, Einstein predicted that mass should emit gravity waves. They'll be weak, though, so it would take very massive objects to produce waves detectable here on Earth. One experiment working towards their detection is the Laser Interferometer Gravitational-Wave Observatory (or LIGO). It should be able to detect the most powerful gravity waves as they pass through the Earth. And a space-based observatory planned for launch in 2015 called LISA should be stronger still.

View full article (http://www.universetoday.com/am/publish/eanna_flanagan_gravity.html)
What do you think about this story? post your comments below.
Wait...maybe I need to re-read material on Einstein's Relativity Theory, but I thought it could described exactly why there AREN'T gravitational waves...as similar to electromagentism. Gravity isn't directly an attraction of one object to another. Two masses don't have some extremely hard to identify energy that brings them together like a nuclear force, objects with mass distort space and time causing two masses to endlessly fall towards each other.

Maybe I'm not understanding exactly what they think they are looking for.

Jerry
2008-Jan-24, 04:19 AM
Wait...maybe I need to re-read material on Einstein's Relativity Theory, but I thought it could described exactly why there AREN'T gravitational waves...as similar to electromagentism. Gravity isn't directly an attraction of one object to another. Two masses don't have some extremely hard to identify energy that brings them together like a nuclear force, objects with mass distort space and time causing two masses to endlessly fall towards each other.

Maybe I'm not understanding exactly what they think they are looking for.
As massive objects close upon each other in a tight binary rotation, there is a tidal effect: just as the Earth and Luna create a gravitational pulse relative to the Sun. Buy why a wave? The finite speed of light creates a slight delay between where the head of the 'wave' is, and the changing position of the two bodies. (Note that in calculating the orbit of the moon about the earth, the time delay is correctly ignored because in space-time gravitational force is a vector, not a point argument, and the differential is extremely small.) If the masses of the bodies are great enough, these frame-dragging effects should result in the net loss of energy as a 'tear' in space-time. This anticipated loss of energy is what Hulse et al carefully quantified in an orbiting pair of neutron stars.

However (there is always a however) recent observations of Newtron stars have revealed pulsing emissions of X-rays and such that might contraindicate the Hulse et al studies. Without supporting evidence for gravitational waves from the very spendy gravity wave antenna constructed on earth; there remains a possibility that the energy that is emitted by Neutron pairs is not properly understood.

trinitree88
2008-Jan-25, 10:14 PM
As massive objects close upon each other in a tight binary rotation, there is a tidal effect: just as the Earth and Luna create a gravitational pulse relative to the Sun. Buy why a wave? The finite speed of light creates a slight delay between where the head of the 'wave' is, and the changing position of the two bodies. (Note that in calculating the orbit of the moon about the earth, the time delay is correctly ignored because in space-time gravitational force is a vector, not a point argument, and the differential is extremely small.) If the masses of the bodies are great enough, these frame-dragging effects should result in the net loss of energy as a 'tear' in space-time. This anticipated loss of energy is what Hulse et al carefully quantified in an orbiting pair of neutron stars.

However (there is always a however) recent observations of Newtron stars have revealed pulsing emissions of X-rays and such that might contraindicate the Hulse et al studies. Without supporting evidence for gravitational waves from the very spendy gravity wave antenna constructed on earth; there remains a possibility that the energy that is emitted by Neutron pairs is not properly understood.

Jerry. There ought to be cyclical change of magnetic field with commensurate emission spike....similar to the sun's 11-year polarity flip, but with a very high Reynolds number for the superfluid in the neutron stars, too. So it ought to be rapid. pete

see'http://www.journals.uchicago.edu/doi/abs/10.1086/507576

Jerry
2008-Feb-06, 06:18 AM
GRB-triggered searches for gravitational waves in LIGO data

Authors: Alexander Dietz, for the LIGO Scientific Collaboration



The LIGO gravitational wave detectors have recently reached their design sensitivity and finished a two-year science run. During this period one year of data with unprecedented sensitivity has been collected. I will briefly describe the status of the LIGO detectors and the overall quality of the most recent science run. I also will present results of a search for inspiral waveforms in gravitational wave data coincident with the short gamma ray burst detected on 1st February 2007, with its sky location error box overlapping a spiral arms of M31. No gravitational wave signals were detected and a binary merger in M31 can be excluded at the 99% confidence level.

minorwork
2008-Feb-06, 06:54 AM
So is gravity electromagnetic like light? I had it figured as a measurement phenomena or a very weak force of unknown nature. Is LIGO an instrument whose successful detection of gravity waves confirm gravity's electromagnetic nature?

01101001
2008-Feb-06, 07:24 AM
GRB-triggered searches for gravitational waves in LIGO data

Authors: Alexander Dietz, for the LIGO Scientific Collaboration

Now, with links...

UC Davis: arXiv:0802.0393 (http://front.math.ucdavis.edu/0802.0393)

GRB-triggered searches for gravitational waves in LIGO data (PDF) (http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.0393v1.pdf)

Jerry
2008-Feb-06, 07:06 PM
So is gravity electromagnetic like light? I had it figured as a measurement phenomena or a very weak force of unknown nature. Is LIGO an instrument whose successful detection of gravity waves confirm gravity's electromagnetic nature?

No - See 101101101's links. The LIGO detection system consist of long suspended masses and an interferometer system that detects subtle changes.

minorwork
2008-Feb-07, 10:10 PM
Would the following be a possible upgrade to the land based LIGO?

http://physicsworld.com/cws/article/news/32802

GOURDHEAD
2008-Feb-08, 02:08 PM
How does gravitational wave theory guide (constrain) their search in selecting the frequency of the expected distortions in the critical members of the observing equipment, the temporal separation between the GRB photon observation and impingement on the "gravity wave telescope" of the gravity wave effect, and the assessment of whether we know of material capable of responding to the hyper-short waves of the possibly extremely high energy domains where detectable gravity waves might live? I.e.: did they look long enough at the right frequency with capable constructions? [I'm a gravity wave skeptic.] A poor analogy might be determining the probability of hurricanes making waves on the surface of a frozen ocean.

Jerry
2008-Feb-09, 06:19 AM
There have been many attempts to capture gravitational waves - at many frequencies. The long wave antenna, such as LIGO, were constructed after the failure of higher frequency devices, such as Allegro. Improving our understanding of gravitational forces is proving very challenging.

01101001
2008-Feb-09, 07:08 AM
http://physicsworld.com/cws/article/news/32802


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minorwork
2008-Feb-09, 10:30 AM
I did not register. Physicsworld is a widget on my google homepage, though.
If acceptable for reprint here, I submit the copied article.

from February 7, 2008 physicsworld.com titled Putting the Squeeze on Quantum Noise
Physicists in Germany have produced a beam of “squeezed” laser light with a record low level of quantum noise. Their technique reduced the noise in an infrared beam by 90% and could someday be used to allow gravitational wave detectors to probe deeper into space and to create quantum information and cryptography systems.

The electric field of a light beam always carries some inherent quantum noise — the result of fluctuations in amplitude and phase caused by the intrinsic quantum nature of the photons. Now Roman Schnabel and colleagues at the Max Planck Institute for Gravitational Physics and Leibniz University in Hanover have found a way to remove much of this noise from a 1064-nm laser beam using a double-refraction crystal and green laser light (Phys Rev Lett 100 033602).

Storing photons
“The green laser prepares the crystal by causing the electron cloud of the crystal’s atoms to oscillate with the frequency of the green light,” explained Schnabel. “In this state, the crystal can then store photons sent in by the infrared beam.” When the photon flux is then reduced these stored photons are replaced back into the beam, which in turn achieves a more regular photon distribution.

As a result, phase fluctuations are almost eliminated from the beam. “We achieved a quantum noise reduction level of 90%,” said Schnabel, who added “Until now a good result was a reduction by a factor of four, down to 25%”.

The researchers believe that the squeezing strength in their set-up is limited by optical losses rather than phase fluctuations, and so could be improved further.

Using squeezed light we can extend the reach of gravitational wave detectors by a factor of three
Roman Schnabel, Max Planck Institute for Gravitational Physics and Leibniz University
Quantum noise can perturb sensitive measurements, such as those made by the Laser Interfermometer Gravitational Wave Observatory (LIGO) facilities in the US. All current LIGO detectors use infrared lasers to search for the tiny interference patterns that are predicted to appear when gravitational waves interact with the beams, but the extreme weakness of the waves makes them almost impossible to detect.

According to Schnabel, the uniform intensity of squeezed light could make these detectors more sensitive and allow it to probe deeper into space where the elusive waves are created. “Using squeezed light we can extend the reach of gravitational wave detectors by a factor of three,” he said.


Another application could be quantum information and cryptography. “Squeezed states have been used to demonstrate several quantum information protocols, construct entangled states of light and demonstrate quantum teleportation,” said Schnabel.

About the author
Tim Hayes is a reporter for optics.org and Optics & Laser Europe.

In any case, the LIGO guys have probably known of this before me.

Eratosthenes
2008-Feb-09, 12:12 PM
What do I think about the story?
It is incomplete and a bit of a tease, it mentions that gravity keeps beer from floating out of one's glass, but does not even attempt to explain why gravity causes more beer to fall to the ground than any other liquid I drink!

Jerry
2008-Feb-10, 12:47 AM
What do I think about the story?
It is incomplete and a bit of a tease, it mentions that gravity keeps beer from floating out of one's glass, but does not even attempt to explain why gravity causes more beer to fall to the ground than any other liquid I drink!

Ya, and the cheaper the beer, the more of it that ends up on the ground.

rtomes
2008-Feb-13, 09:59 PM
I think that these gravitational detection experiments are looking in the wrong frequency range for gravitational waves. The best frequency to look at is right around 10^-4 Hz and maybe up to 10^-2 Hz. Even lower frequencies would also be good, but probably more difficult to detect.

Jerry
2008-Feb-17, 11:42 PM
Is it even technically feasible to search at such long wavelengths? It seems you would need an antenna several times the diameter of the earth.


So is gravity electromagnetic like light? I had it figured as a measurement phenomena or a very weak force of unknown nature. Is LIGO an instrument whose successful detection of gravity waves confirm gravity's lectromagnetic nature?
LIGO would confirm the non-electromagnetic nature - it is quite literally a mass displacement antenna.

(Personally, I am of the opinion gravitational forces are electromagnetic; and that is why I don't expect the mass detectors to be successful.)

Tricky Woo
2008-Feb-18, 12:23 AM
Also makes me nervous that nothing's been detected as yet.

TW

minorwork
2008-Feb-18, 12:31 AM
Is it even technically feasible to search at such long wavelengths? It seems you would need an antenna several times the diameter of the earth.


LIGO would confirm the non-electromagnetic nature - it is quite literally a mass displacement antenna.

(Personally, I am of the opinion gravitational forces are electromagnetic; and that is why I don't expect the mass detectors to be successful.)

If electromagnetic, then a reasonably simultaneous occurence with a Gamma Ray Burst is expected. And so LIGO data is searched for the association around the time of the GRB. If I understand correctly.

Isn't gravity a space/time distortion? What limits the speed of this shadowy affect? I know the speed of light is the accepted speed limit of anything in a vacuum. What experiment has confirmed gravity's affects at light speed?

Jerry
2008-Feb-19, 03:47 AM
Isn't gravity a space/time distortion? What limits the speed of this shadowy affect? I know the speed of light is the accepted speed limit of anything in a vacuum. What experiment has confirmed gravity's affects at light speed?
There are no local confirmations - the 'frame dragging' effects expected to be detected by the Gravity-B probe (http://en.wikipedia.org/wiki/Gravity_Probe_B) are/were expected to confirm the speed-of-light delay in gravitation wave propagation. But more than two years after this space probe completed its mission, the results are still being tabulated. It is clear the signature is either mask by unanticipated interferences or unexpected physics.

Frankly, I expected the Gravity-B probe (http://en.wikipedia.org/wiki/Gravity_Probe_B) to confirm Einstein's predictions, or produce results that are at least to first-order consistent with Relativistic frame dragging. The probe was unsuccessful.

[The additional massaging of the data necessary to 'confirm' the original hypothesis invalidates the test. Why? If the hypothesis being tested was not consistent with well established theory, there is NO WAY researchers could say that after significant recalculation of the baseline, they have proven an alternative hypothesis to General Relativity. A truly valid test of relativity must also be able to invalidate the theory, if and when the results differ from the prediction. The additional correction factors don't allow such a conclusion.]


If electromagnetic, then a reasonably simultaneous occurence with a Gamma Ray Burst is expected. And so LIGO data is searched for the association around the time of the GRB. If I understand correctly.

There was a confirmed Gamma Ray Burst associated with the explosion of Supernova '1987A' - this was a stunning (and to most supernova researchers initially an unbelievable) event; a relatively weak gamma ray; so we know at least one type of supernova can create a gamma ray burst. LIGO was not operational at the time, but none of the generation of gravity wave detectors that were operating at the time supernova 1987A exploded produced confirmable evidence of a gravitational wave.


Supernova '1987A' demonstrated many aspects of a binary event, so the gamma ray burst may have been directional (conversely, the strongest gamma ray may not have been vented in our direction). SWIFT data suggests gamma rays - whatever there source, are not so strongly beams as was calculated less than a decade ago.

In any case, the underlying source of many gamma ray bursts remains a major cosmic mystery. I find it curious that there is so much confidence in the cosmological implications predicated upon supernova research; while at the same time so little is understood about the supernova and gamma ray mechanism.

(If gravity is truly an electromagnetic phenomenom, there are implications for all electromagnetic/gravitational interactions - obviously speculation here swells outside of the mainstream, but since gamma rays are not understood within the context of MS physics; how does one explore the possibilities without ruffling feathers?)

minorwork
2008-Feb-19, 12:53 PM
[The additional massaging of the data necessary to 'confirm' the original hypothesis invalidates the test. Why? If the hypothesis being tested was not consistent with well established theory, there is NO WAY researchers could say that after significant recalculation of the baseline, they have proven an alternative hypothesis to General Relativity. A truly valid test of relativity must also be able to invalidate the theory, if and when the results differ from the prediction. The additional correction factors don't allow such a conclusion.]

You think then that a filter designed to weed out electrostatic distortion of the frame dragging effect negates the science? The LIGO team is using algorithmic filters in the same manner to achieve design accuracy. I would not be as proud of the results using such filters when the experimental raw data was supposed to confirm or deny predictions. I think this is your position, Jerry.

It seems that the tides on Earth are an indicator of sorts for gravity varying as they do and synergistically with lunar/solar influences. The LHC at Cern allows for these distortions in their soon to be computations. Would these tidal signals show on LIGO or Gravity-B probe data or are these to be filtered out as well? And then would not planetary effects emerge? I've not heard of this, but figure our instruments are not of sufficient resolution.

Jerry
2008-Feb-20, 02:44 AM
You think then that a filter designed to weed out electrostatic distortion of the frame dragging effect negates the science? The LIGO team is using algorithmic filters in the same manner to achieve design accuracy. I would not be as proud of the results using such filters when the experimental raw data was supposed to confirm or deny predictions. I think this is your position, Jerry.

Close. As a general principle, any test of a widely accepted theory must include the possibility of negating the theory if the results are different from what was expected and cannot be accounted for in the error analysis.

In the case of the Gravity B probe; published statements seem to indicate that when the probe entered the final ~two months of calibration, signal that was thought to be due to frame dragging was found to be attributable to interaction between the gyroscope housing and the gyroscopes (patch effects). Worse still, the effects were not constant over time - so there is a an variation in the 'baseline' that is of sufficient magnitude to mask frame dragging; and no competent way to separate these patch effects from the expected GR signal.


It seems that the tides on Earth are an indicator of sorts for gravity varying as they do and synergistically with lunar/solar influences. The LHC at Cern allows for these distortions in their soon to be computations. Would these tidal signals show on LIGO or Gravity-B probe data or are these to be filtered out as well? And then would not planetary effects emerge? I've not heard of this, but figure our instruments are not of sufficient resolution.
All challenging elements for LIGO; but LIGO has many advantages over the gravitity B probe: LIGO and LIGO contemporaries are phase and time synchronized, so that any gravitation signal picked up by one should be observe by all probes, with an appropriate time delay. This allows local signal directional filtering.

The other big advantage of the surface antenna, is that calibrations can be checked and reverified at any time; new constraints tested and certified. None of the new assumptions necessary to extract frame dragging data from Gravity B probe noise can be verified - this was a 650 million dollar one-shot experiment that perhaps never should have gotten off the ground.