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Author Topic: Hunt Is On for Gravity Waves in Space-Time  (Read 1515 times)

Offline Emc2

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Offline CliffordK

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #1 on: 18/08/2012 18:17:43 »
Thorne predicted LIGO's first discovery will come between 2014 and 2017.

That seems a bit optimistic. 

According to the link in the article,

For years, scientists have been trying — and failing — to detect theoretical ripples in space-time called gravitational waves.

Consider that the entire gravitational force of the Milky Way is about 200 pm/s2.  Or, about 2 x 10-10 m/s2.  Divide that by 300 billion stars, and the entire gravitational field due to any single star is about 6 x 10-22 m/s2.  If only a fraction of that is converted into gravitational waves, then the precision would have to be very high to detect it.

Keep in mind that the total mass is essentially unchanged with a stellar collision, or a star colliding with a black hole.

One may be limited to only picking up the gravitational waves from nearby stars in the Milky Way, if such waves in fact exist.

The LISA space based gravity wave detector may have held some promise, but it has now been shelved for the time being.  And, it may be difficult to acquire future funding unless the ground based system actually finds something, or the satellites could be multi-purposed.
 

Offline evan_au

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #2 on: 19/08/2012 06:52:36 »
A Nobel Prize was awarded in 1993 for detecting that gravitational waves are emitted by circling neutron stars. http://en.wikipedia.org/wiki/Gravitational_wave

Scientists are always trying to improve the frequency range and sensitivity of their gravity-wave detectors.

As I recall, the one in Gin Gin, Western Australia claims to be able to detect oscillations with periods up to 20 seconds, which might be seen in the final stage of two neutron stars orbiting each other, and gradually approaching closer by radiating away their gravitational potential energy as gravity waves. http://www.gravity.uwa.edu.au/

The sensitivity at Gin Gin is such that they can only detect mergers in our part of the galaxy. The major unknown is how long they might have to wait before the next detectable event occurs - close enough to us, large enough merging objects, and orbiting in the right frequency range.

« Last Edit: 19/08/2012 06:57:09 by evan_au »
 

Offline Emc2

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #3 on: 19/08/2012 09:01:48 »
yes, maybe they can detect them, maybe not..if they are there.
 

Offline CliffordK

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #4 on: 19/08/2012 12:40:24 »
A Nobel Prize was awarded in 1993 for detecting that gravitational waves are emitted by circling neutron stars. http://en.wikipedia.org/wiki/Gravitational_wave
Reading the Wiki Link:
Quote
Although gravitational radiation has not been directly detected, there is indirect evidence for its existence. For example, the 1993 Nobel Prize in Physics was awarded for measurements of the Hulse-Taylor binary system which suggests gravitational waves are more than mathematical anomalies. Various gravitational wave detectors exist. However, they remain unsuccessful in detecting such phenomena.

So, still no definitive proof of the phenomena. 

Following the link in Wikipedia:
The orbit has decayed 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. The total power of the gravitational radiation (waves) emitted by this system presently, is calculated to be 7.35 × 1024 watts

So, while this may support a theory of gravity waves, it still lacks proof of their existence as being observed from Earth, and all remains theoretical. 

The space based system seems like it is most likely to succeed, but could be plagued with issues such as clock synchronization which plague many relativistic experiments.
 

Offline Emc2

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #5 on: 21/08/2012 08:28:32 »
no, no proof, but maybe this study can shed some light on the subject, and either advance this theory, or search for new ones.......always more questions, every time we get one answer.....lol...it never ends, of course humans are young in this universe, others may be millions of years ahead of us in technology already.......might take us thousands of years yet, too many unknowns yet, but the pieces are getting easier to find lately..
 

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Re: Hunt Is On for Gravity Waves in Space-Time
« Reply #5 on: 21/08/2012 08:28:32 »

 

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