Laying the basis for gravitational wave detection

Jun 27, 2012
Laying the basis for gravitational wave detection
Credit: Thinkstock

Astronomers have long relied on light waves to provide information about astrophysical objects. The hunt for gravitational waves, highly sought after but terribly elusive, should get a boost from theoretical studies by European researchers.

Gravitational waves (GWs), first predicted as a result of ’s general relativity theory, are small distortions of space-time geometry that propagate through space like waves, travelling at the speed of light. However, they cannot be absorbed, for example by ‘stuff’ between the observer and the source, so they’re not obscured or scattered like light.

With enhancements greatly increasing sensitivity of two of the most important GW detectors, EU researchers supported by funding of the ‘Compact binaries as gravitational-wave sources’ (Compact Binaries) project sought to investigate potential sources of GWs in order to evaluate detector performance as well as to guide future observational experiments.

GWs are produced by almost all moving masses. Compact binaries, consisting of two compact objects (white dwarfs, or black holes) orbiting each other, are excellent potential sources due to both their high-density mass and their motion – the perfect recipe for GW production.

The Compact Binaries team first studied fast-spinning neutron stars (pulsars). Neutron stars have a diameter around 20 km and masses about 4 times greater than that of the Sun. The rotating versions are pulsars, so called because emitted electromagnetic waves are seen from the Earth in pulses much like the light from a rotating lighthouse beacon.

Scientists calculated estimates of pulsar binary birth rates based on beaming fractions. In addition, they published a summary of predicted detection rates based on all available experimental and theoretical work for all types of binaries detectable by ground-based GW detectors.

Another source of GWs and among the most mysterious objects in the night sky are gamma-ray bursts (GRBs), very short intense flashes of high energy gamma-ray photons. These bursts have recently been seen to be followed in more than 30 % of cases by brief X-ray flares. Compact Binaries researchers developed a model of a binary system that could power the X-ray flare on the time scale observed.

Compact Binaries results should have important impact on the effective design of observational experiments, enhancing Europe’s position in the race to detect the first GWs.

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User comments : 23

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Vendicar_Decarian
2.7 / 5 (7) Jun 27, 2012
Why isn't this research being funded exclusively by corporate donations?
gopher65
5 / 5 (10) Jun 27, 2012
Why isn't this research being funded exclusively by corporate donations?

Because publicly held corporations aren't interested in doing research that won't be able to be commercialized for hundreds of years. If it takes longer than 5-10 years to come to market, they worry that it will take away resources that they could use for other matters (ie, other research that may be more marketable, employee benefits packages to ensure that they can snag the best workers, stockholder dividends, which inflate the stock price and therefore make a hostile takeover less likely, etc).

The intrinsic nature of a publicly held corporation is to be geared to the very short term. Privately held corporations don't have that same limitation, but corps don't tend to stay privately held indefinitely. Eventually they go public, and in doing so lose their edge.

(Of course government funded research is the best for long term basic science projects like this one, for multiple reasons.)
Archea
1.6 / 5 (7) Jun 28, 2012
Gravitational waves (GWs) don't exist and their existence in general relativity is an artifact of linearizion of Einstein field equations - which enables to solve them for purpose of high school lectures and writing of silly publications - but which leads into many unphysical results too. As Eddington pointed out already before many years, gravitational waves do not have a unique speed of propagation. The speed of the alleged waves is coordinate dependent. A different set of coordinates yields a different speed of propagation and such waves would propagate like noise. The notoriously known CMBR noise is the manifestation of GWs instead. But the useless and nonsensical search of GWs still remains pretty lucrative business, as the detectors of GWs are one of the larges and most expensive physical devices developed so far. So I don't expect, the physicists will end with it soon, until their money will be going.
gopher65
5 / 5 (4) Jun 28, 2012
Archea: the side effects of gravitational waves have been directly observed. This includes the spiraling together of massive binary systems. There is no other way to explain such spiraling than gravitational waves.

While there are other models of reality other than general relativity, all the models that can account for such spiraling also include gravitational waves. No model that doesn't include gravitational waves is able to account for those observed effects. Thus, gravitational waves exist, whether you want to "believe" in reality or not.
Archea
1 / 5 (4) Jun 28, 2012
Archea: the side effects of gravitational waves have been directly observed. This includes the spiraling together of massive binary systems.
Actually it's the only effect of GWs observed so far. And I'm not doubting the gravitational wave existence as such - I'm just saying, everyone can observe it with his own analogue TV set and no billion dollars investments are required for it.
frajo
5 / 5 (2) Jun 28, 2012
already before many years


Zephyr's signal again.
TheGhostofOtto1923
2.3 / 5 (3) Jun 28, 2012
already before many years


Zephyr's signal again.
and terriva and tkclick etcetc. Where you been? Out fomenting anarchy in the streets? SkepticHeretic hasnt posted since february?
frajo
5 / 5 (1) Jun 29, 2012
Where you been? Out fomenting anarchy in the streets?
The anarchy in the streets is an inevitable reaction to the anarchy of the financial markets.
Eoprime
5 / 5 (1) Jun 29, 2012
Gravitational waves (GWs) don't exist and their existence in general relativity is an....

.. And I'm not doubting the gravitational wave existence as such..


You are such a nut...
AtlasT
1 / 5 (4) Jun 29, 2012
I presume, the gravitational waves do exist in extradimensions of space-time in similar way, like the sound waves spreading trough the underwater in longitudinal waves. But such waves will appear/behave like the noise at the water surface, i.e. without any harmonic component. Therefore the relativists, who are claiming, the binary pulsars are losing their energy in gravitational waves have their truth, but the people who are trying to detect them in audible spectrum in our space-time have no chance with it.

Got it? The physics is not for nuts...
AtlasT
1 / 5 (4) Jun 29, 2012
Recently the idea of holographic noise emerged in some sector of holographic model. This idea is the step in the right direction in the sense, it considers the gravitational waves as a noise and it monitors its amplitude only instead of waves as such. But because the upper limit for detection of holographic noise is limited just with frequency of CMBR noise, prof. Hogan, who is trying to detect this noise is forced to avoid just the frequencies, which is he actually supposed to measure, i.e. the GHz frequencies of CMBR noise. Anyway, the holometer costs another billion of dollars, which are essentially wasted for tax payers, just because the physicists don't realize the meaning of their own theories. This is the reason why I'm saying, the community of experts will always find the correct solution, but just at the moment, when all possible options are already excluded carefully.
TheGhostofOtto1923
2.3 / 5 (3) Jun 29, 2012
Where you been? Out fomenting anarchy in the streets?
The anarchy in the streets is an inevitable reaction to the anarchy of the financial markets.
Except that if it is Inevitable then it would have been Anticipated and thus Choreographed to Benefit rather than endanger. Obviously.

Oh and jigga is also AtlasT
Got it? The physics is not for nuts...
:-P
Sanescience
not rated yet Jun 30, 2012
I always wondered if gravity waves represented a "radiance" of energy causing two orbiting bodies to loose momentum beyond that explained by other factors. Or stated differently, in a perfect environment would two orbiting masses simply continue to orbit forever if not for gravity waves?
antialias_physorg
4 / 5 (1) Jun 30, 2012
. Or stated differently, in a perfect environment would two orbiting masses simply continue to orbit forever if not for gravity waves?

Probably not since gravity deformes objects - and that deformation energy has to come from somewhere (and it can come only from gravity). So, no, I don't think even in an ideal case without gravity waves would two objects orbit each other indefinitely.

Eikka
not rated yet Jun 30, 2012
However, they cannot be absorbed, for example by stuff between the observer and the source, so theyre not obscured or scattered like light.


If this is true, then technically it should be impossible to observe them at all, because there's no measuring device that can feel the energy that is being transmitted by the wave.

For example, a cork floating on the surface of a lake can measure the presence of a wave by bobbing up and down, which means it absorbs some of the wave's energy in going up, and releases it by going down, changing the way the wave propagates in the process.

If gravitational waves are being generated by stuff, then they must be influenced by stuff and vice versa. If something can feel the presence of the wave, then the wave must feel the presence of that something. Otherwise you break the conservation of energy.
antialias_physorg
5 / 5 (1) Jun 30, 2012
On the other hand this would mean that if you put enough stuff in the way you could 'shield' gravity wave effects from stuff on the other side (neglecting for the moment that you're adding stuff which will increase gravity felt at your point of measurement)

But that doesn't seem to be the case. Currently there seems to be no way of 'taking away' from the gravitational effect of one body on another.
Archea
1 / 5 (3) Jun 30, 2012
In dense aether model the cold dark matter around massive objects is the result of gravitational wave shielding with neighboring massive objects. The gravity field is the result of shielding of these waves with massive bodies itself.
IronhorseA
not rated yet Jun 30, 2012
I presume, the gravitational waves do exist in extradimensions of space-time in similar way, like the sound waves spreading trough the underwater in longitudinal waves. But such waves will appear/behave like the noise at the water surface, i.e. without any harmonic component. Therefore the relativists, who are claiming, the binary pulsars are losing their energy in gravitational waves have their truth, but the people who are trying to detect them in audible spectrum in our space-time have no chance with it.

Got it? The physics is not for nuts...


According to physicists who specialize in relativity, gravitational waves don't transmit energy at all. (Cooperstock, et. al.)
Archea
1 / 5 (2) Jun 30, 2012
According to me, the transmission of energy with gravitational waves is the only method, hot to detect them - compare the Hulse- Taylor pulsars for example. This pair of pulsars is losing an energy transmitted with gravitational waves and its distance decreases gradually.
Torbjorn_Larsson_OM
4.5 / 5 (4) Jul 01, 2012
"Gravitational waves [comes out of] linearizion [sic] of Einstein field equations."

They don't, they come out of the weak gravity limit and would exist anyway, same as Newton gravity comes out and its planetary orbits exist anyway. http://en.wikiped...al_waves :

"Since Einstein's equations are non-linear, arbitrarily strong gravitational waves do not obey linear superposition, making their description difficult. However, for weak fields, a linear approximation can be made. ... Some exact solutions describe gravitational waves without any approximation, e.g., a wave train traveling through empty space ...".

This is also like how gravitons comes out of the weak gravity limit if you quantize the theory. They too have problems of description as you move to the strong case (e.g. you need string theory).

I seriously doubt you know what linearization is, since you can't even spell it.

Also, there is no aether, it was rejected over a century ago.
Shelgeyr
1 / 5 (2) Jul 02, 2012
GWs are produced by almost all moving masses.

There is no evidentiary basis for this statement. It is only hypothetical at best. They need to stop stating postulated assumptions as if they were facts.

With enhancements greatly increasing sensitivity of two of the most important GW detectors,...

How do they know that they've greatly enhanced the sensitivity? If one thing has no ability to detect any evidence of GWs, and you do something fancy and high-tech-ish to it and still have no ability to detect GWs, how the bleep have you "enhanced" its sensitivity?

@gopher65 said:
Archea: the side effects of gravitational waves have been directly observed.

No. An observation has been made (many, actually) that was capriciously and arbitrarily attributed to GWs. That doesn't make them evidence of GWs. You're seeing an effect and assuming the cause and calling it scientific fact. You shouldn't.
AtomThick
not rated yet Jul 02, 2012
If gravitational waves are out there, we could also have stationary gravitational waves. Wouldn't those mimic the long sought dark matter? A stationary GW would create a stationary space-time curvature which to us would seem that there is an invisible matter in that place generating it.
frajo
not rated yet Jul 02, 2012
I seriously doubt you know what linearization is, since you can't even spell it.

You dismiss beforehand the possibility of a spelling error?
Did you check the bias potential?