bobbymike
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Rumors - Detection of Gravitational Waves?
- Thread starter bobbymike
- Start date
Or as caused by the space-time shock-wave of humongous Alien craft arriving?
- as predicted by Joe Haldeman in 'Mindbridge'?
Are our gravity wave detectors at least as effective..
.. as the inter-planetary bolide detection & defence systems we have currently operational?
Hey, just askin'..
- as predicted by Joe Haldeman in 'Mindbridge'?
Are our gravity wave detectors at least as effective..
.. as the inter-planetary bolide detection & defence systems we have currently operational?
Hey, just askin'..
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Here is a link that actually works...
Last week the Harvard-Smithsonian Center for Astrophysics (CfA) stated rather nonchalantly that they will be hosting a press conference on Monday, March 17th, to announce a “major discovery.” Without a potential topic for journalists to muse on, this was as melodramatic as it got.
But then the Guardian posted an article on the subject and the rumors went into overdrive. The speculation is this: a U.S. team is on the verge of confirming they have detected primordial gravitational waves — ripples in the fabric of spacetime that carry echoes of the big bang nearly 14 billion years ago.
If there is evidence for gravitational waves, it will be a landmark discovery, ultimately changing the face of physics.
Not only are gravitational waves the last untested prediction of Albert Einstein’s General Theory of Relativity, but primordial gravitational waves will allow astronomers to glimpse the universe in its infancy.
“It’s been called the Holy Grail of cosmology,” Hiranya Peiris, a cosmologist from University College London, told the Guardian. “It would be a real major, major, major discovery.” Any convincing evidence would almost certainly lead to a Nobel prize.
The signal is rumored to have been found by a telescope known as BICEP (Background Imaging of Cosmic Extragalactic Polarization), which scans the sky from the south pole, looking for a subtle effect in the cosmic microwave background (CMB): the radiation released 380,000 years after the big bang when space became transparent to light and photons were allowed to travel freely across the universe.
While the CMB has been mapped in exquisite detail, astronomers think that hidden within the map is a second fingerprint, which would reveal gravitational waves. Its radiation was scattered toward us from the universe’s earliest atoms, similar to the way blue light is scattered toward us from the atoms in the sky. And just as the sky is slightly polarized — the waves have a preferred orientation — so is the CMB (on the level of a few percent).
Cosmologists are digging through the data, searching for a subtle twist in the polarized light, known as B-modes. If a gravitational wave moves through the fabric of spacetime, it will squeeze spacetime in one direction (the universe will look a little hotter) and stretch it in another (the universe will look a little cooler). The photons will scatter with a preferred direction, leaving a slightly polarized imprint on the CMB, due to the passing gravitational wave.
Not only will detecting this slight polarization pattern in the CMB allow astronomers to uncover evidence of primordial gravitational waves but they will provide proof that immediately after the big bang the universe expanded exponentially — inflated — by at least a factor of 1025. While the theory of inflation is a pillar of big bang cosmology and helps explain key features of the observable universe today (i.e. why the universe is outstandingly uniform on such massive scales), many physicists don’t buy it. It remains a theoretical framework because we can’t explain what physical mechanism would have driven such a massive expansion, let alone stop it.
Inflation is the only mechanism with the ability to amplify gravitational waves, born from quantum fluctuations in gravity itself, into a detectable signal.
“If a detection has been made, it is extraordinarily exciting,” Andrew Jaffe, a cosmologist from Imperial College, London, told the Guardian. “This is the real big tick-box that we have been waiting for. It will tell us something incredibly fundamental about what was happening when the universe was only 10-34 seconds old.”
But even if the rumors prove true, it’s crucial to remain skeptical. Extracting the signal is extremely tricky. The CMB’s temperature varies by a few parts in 100,000. In comparison, B-modes account for just one part in 10 million in the CMB temperature distribution.
The microwaves also travel across the entire observable universe first. Only last year the signal was detected in the CMB for the first time using the South Pole Telescope, but it was in fact distorted by intervening clusters of galaxies and not intrinsic to the CMB itself.
The announcement will be made on Monday at noon EST.
Last week the Harvard-Smithsonian Center for Astrophysics (CfA) stated rather nonchalantly that they will be hosting a press conference on Monday, March 17th, to announce a “major discovery.” Without a potential topic for journalists to muse on, this was as melodramatic as it got.
But then the Guardian posted an article on the subject and the rumors went into overdrive. The speculation is this: a U.S. team is on the verge of confirming they have detected primordial gravitational waves — ripples in the fabric of spacetime that carry echoes of the big bang nearly 14 billion years ago.
If there is evidence for gravitational waves, it will be a landmark discovery, ultimately changing the face of physics.
Not only are gravitational waves the last untested prediction of Albert Einstein’s General Theory of Relativity, but primordial gravitational waves will allow astronomers to glimpse the universe in its infancy.
“It’s been called the Holy Grail of cosmology,” Hiranya Peiris, a cosmologist from University College London, told the Guardian. “It would be a real major, major, major discovery.” Any convincing evidence would almost certainly lead to a Nobel prize.
The signal is rumored to have been found by a telescope known as BICEP (Background Imaging of Cosmic Extragalactic Polarization), which scans the sky from the south pole, looking for a subtle effect in the cosmic microwave background (CMB): the radiation released 380,000 years after the big bang when space became transparent to light and photons were allowed to travel freely across the universe.
While the CMB has been mapped in exquisite detail, astronomers think that hidden within the map is a second fingerprint, which would reveal gravitational waves. Its radiation was scattered toward us from the universe’s earliest atoms, similar to the way blue light is scattered toward us from the atoms in the sky. And just as the sky is slightly polarized — the waves have a preferred orientation — so is the CMB (on the level of a few percent).
Cosmologists are digging through the data, searching for a subtle twist in the polarized light, known as B-modes. If a gravitational wave moves through the fabric of spacetime, it will squeeze spacetime in one direction (the universe will look a little hotter) and stretch it in another (the universe will look a little cooler). The photons will scatter with a preferred direction, leaving a slightly polarized imprint on the CMB, due to the passing gravitational wave.
Not only will detecting this slight polarization pattern in the CMB allow astronomers to uncover evidence of primordial gravitational waves but they will provide proof that immediately after the big bang the universe expanded exponentially — inflated — by at least a factor of 1025. While the theory of inflation is a pillar of big bang cosmology and helps explain key features of the observable universe today (i.e. why the universe is outstandingly uniform on such massive scales), many physicists don’t buy it. It remains a theoretical framework because we can’t explain what physical mechanism would have driven such a massive expansion, let alone stop it.
Inflation is the only mechanism with the ability to amplify gravitational waves, born from quantum fluctuations in gravity itself, into a detectable signal.
“If a detection has been made, it is extraordinarily exciting,” Andrew Jaffe, a cosmologist from Imperial College, London, told the Guardian. “This is the real big tick-box that we have been waiting for. It will tell us something incredibly fundamental about what was happening when the universe was only 10-34 seconds old.”
But even if the rumors prove true, it’s crucial to remain skeptical. Extracting the signal is extremely tricky. The CMB’s temperature varies by a few parts in 100,000. In comparison, B-modes account for just one part in 10 million in the CMB temperature distribution.
The microwaves also travel across the entire observable universe first. Only last year the signal was detected in the CMB for the first time using the South Pole Telescope, but it was in fact distorted by intervening clusters of galaxies and not intrinsic to the CMB itself.
The announcement will be made on Monday at noon EST.
I assume they made sure to not repeat the last time they announced gravity waves only to find out it was uncalibrated instrument readings.
www.space.com
Gravitational Waves Detected by LIGO: Complete Coverage
Read all about the mysterious spacetime ripples known as gravitational waves, and what their discovery would mean for astronomy.
www.space.com
Seems like they are getting the hang of this.
2nd gravity wave detection announced
http://www.space.com/33188-gravitational-waves-black-hole-collision-sound-video.html
2nd gravity wave detection announced
http://www.space.com/33188-gravitational-waves-black-hole-collision-sound-video.html
3rd gravity wave detected. Event occurred 3 billion years ago and represents the mass of 2 suns converted into gravity waves. LIGO seems to require a very hefty energy level to spot it. It will be interesting to see how many more gravity waves can be observed once they have instruments capable of seeing much lower levels of energy.
"It was the third confirmed detection of coalescing black holes detected so far by the U.S.-led Laser Interferometer Gravitational-Wave Observatory, or LIGO, a project made up of two observing stations, one near Hanford, Washington, and the other 1,800 miles away near Livingston, Louisiana."
https://spaceflightnow.com/2017/06/01/black-holes-crash-together-and-make-waves/
"It was the third confirmed detection of coalescing black holes detected so far by the U.S.-led Laser Interferometer Gravitational-Wave Observatory, or LIGO, a project made up of two observing stations, one near Hanford, Washington, and the other 1,800 miles away near Livingston, Louisiana."
https://spaceflightnow.com/2017/06/01/black-holes-crash-together-and-make-waves/
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Can this be used for submarine detection 
?
?No
DWG
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Well, if you have two submarines the size of large black holes colliding, maybe
Hmm, 14th Aug may be when a friend was complaining of their LIGO scientist husband being dragged out of bed by their pager at Oh-God-is-that-the-time-you-cannot-be-serious AM.
Hmm, 14th Aug may be when a friend was complaining of their LIGO scientist husband being dragged out of bed by their pager at Oh-God-is-that-the-time-you-cannot-be-serious AM.
bobbymike
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I've heard of SSBNs being so quiet that they are described as "Black Holes in the ocean"DWG said:Well, if you have two submarines the size of large black holes colliding, maybe
Hmm, 14th Aug may be when a friend was complaining of their LIGO scientist husband being dragged out of bed by their pager at Oh-God-is-that-the-time-you-cannot-be-serious AM.
Not exactly news I suppose. There are 4 LIGO facilities now. The 2 in the US, one in Italy (which participated in the 4th detection event), and one in Japan (still under construction). A "small" scale version was built in Germany for detector development work.
With all the dark matter detectors everyone has built over the years, it is interesting that nobody has seen anything but if they do, there is another guaranteed winner.
Nobel physics prize awards discovery in gravitational waves
https://phys.org/news/2017-10-nobel-physics-prize-awarded-scientists.html#nRlv
"Three U.S.-based scientists won the Nobel Physics Prize on Tuesday for detecting faint ripples flying through the universe—the gravitational waves predicted a century ago by Albert Einstein that provide a new understanding of the universe.
Rainer Weiss of the Massachusetts Institute of Technology and Barry Barish and Kip Thorne of the California Institute of Technology won the 2017 prize for a combination of highly advanced theory and ingenious equipment design, Sweden's Royal Academy of Sciences announced."
With all the dark matter detectors everyone has built over the years, it is interesting that nobody has seen anything but if they do, there is another guaranteed winner.
Nobel physics prize awards discovery in gravitational waves
https://phys.org/news/2017-10-nobel-physics-prize-awarded-scientists.html#nRlv
"Three U.S.-based scientists won the Nobel Physics Prize on Tuesday for detecting faint ripples flying through the universe—the gravitational waves predicted a century ago by Albert Einstein that provide a new understanding of the universe.
Rainer Weiss of the Massachusetts Institute of Technology and Barry Barish and Kip Thorne of the California Institute of Technology won the 2017 prize for a combination of highly advanced theory and ingenious equipment design, Sweden's Royal Academy of Sciences announced."
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Fifth Gravitational Wave detection, and observations of the event in the electromagnetic spectrum . . .
cheers,
Robin.
cheers,
Robin.
Unknown object collided with a black hole, heavier than a neutron Star is expected to be, yet lighter than a black hole is expected to be.
In case anyone is interested, gravity wave detections are compiled here:
https://gracedb.ligo.org/superevents/public/O3/
https://gracedb.ligo.org/superevents/public/O3/
Scientists Are Detecting More Gravitational Waves Than Ever Before
The LIGO and Virgo teams have spotted 50 total cosmic signals since 2015
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Im curious if anyone would think to generate its own form of Gravitiational wave now.
DWG
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The safety case for generating and then colliding two supermassive black holes in the lab is probably a bit of a bugger.
Gravitational wave lensing beyond general relativity: Birefringence, echoes, and shadows
ABSTRACT
Gravitational waves (GW), as light, are gravitationally lensed by intervening matter, deflecting their trajectories, delaying their arrival and occasionally producing multiple images. In theories beyond general relativity, new gravitational degrees of freedom add an extra layer of complexity and richness to GW lensing. We develop a formalism to compute GW propagation beyond general relativity over general space-times, including kinetic interactions with new fields. Our framework relies on identifying the dynamical propagation eigenstates (linear combinations of the metric and additional fields) at leading order in a short-wave expansion. We determine these eigenstates and the conditions under which they acquire a different propagation speed around a lens. Differences in speed between eigenstates cause birefringence phenomena, including time delays between the metric polarizations (orthogonal superpositions of
h
+
,
h
×
) observable without an electromagnetic counterpart. In particular, GW echoes are produced when the accumulated delay is larger than the signal’s duration, while shorter time delays produce a scrambling of the waveform. We also describe the formation of GW shadows as nonpropagating metric components are sourced by the background of the additional fields around the lens. As an example, we apply our methodology to quartic Horndeski theories with Vainshtein screening and show that birefringence effects probe a region of the parameter space complementary to the constraints from the multimessenger event GW170817. In the future, identified strongly lensed GWs and binary black holes merging near dense environments, such as active galactic nuclei, will fulfill the potential of these novel tests of gravity.
journals.aps.org
phys.org
ABSTRACT
Gravitational waves (GW), as light, are gravitationally lensed by intervening matter, deflecting their trajectories, delaying their arrival and occasionally producing multiple images. In theories beyond general relativity, new gravitational degrees of freedom add an extra layer of complexity and richness to GW lensing. We develop a formalism to compute GW propagation beyond general relativity over general space-times, including kinetic interactions with new fields. Our framework relies on identifying the dynamical propagation eigenstates (linear combinations of the metric and additional fields) at leading order in a short-wave expansion. We determine these eigenstates and the conditions under which they acquire a different propagation speed around a lens. Differences in speed between eigenstates cause birefringence phenomena, including time delays between the metric polarizations (orthogonal superpositions of
h
+
,
h
×
) observable without an electromagnetic counterpart. In particular, GW echoes are produced when the accumulated delay is larger than the signal’s duration, while shorter time delays produce a scrambling of the waveform. We also describe the formation of GW shadows as nonpropagating metric components are sourced by the background of the additional fields around the lens. As an example, we apply our methodology to quartic Horndeski theories with Vainshtein screening and show that birefringence effects probe a region of the parameter space complementary to the constraints from the multimessenger event GW170817. In the future, identified strongly lensed GWs and binary black holes merging near dense environments, such as active galactic nuclei, will fulfill the potential of these novel tests of gravity.
Gravitational wave lensing beyond general relativity: Birefringence, echoes, and shadows
The authors develop a general formalism to study gravitational wave lensing in alternative theories of gravity, predicting several new signatures, particularly birefringence due to lensing between different metric polarizations, which could serve to scrutinize such theories in hitherto...
Ripples in space-time could provide clues to missing components of the universe
There's something a little off about our theory of the universe. Almost everything fits, but there's a fly in the cosmic ointment, a particle of sand in the infinite sandwich. Some scientists think the culprit might be gravity—and that subtle ripples in the fabric of space-time could help us...
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