Evidence found for gravitational waves!
30 Aug 2012 18:38:33 UTC
Topic 196503
(moderation:
Exciting science news! Here: http://www.universetoday.com/97107/effects-of-einsteins-elusive-gravity-waves-observed/
They detected indirectly what I think is what Einstein@Home is trying to observe directly.. am I right?
Does this have any impact for the project? Could they home in the LIGO detectors on these stars? Or is this not how it works?
Evidence found for gravitational waves!
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Yes it is good news, another system demonstrating loss of energy consistent with gravitational wave radiation as per General Relativity. The first instance to demonstrate this is the so-called Taylor-Hulse system, the discovery of which got those guys the Nobel.
Correct, they've found the energy loss at the 'emitter' and we want to pick it up at the 'receiver'.
Well it gives us more faith that we will one day make a detection via spacetime wiggles at this end. The intention of LIGO is to listen for any and all sources; but knowing sky position, frequency and other signal characteristics in advance would certainly be a shortcut - as opposed to our current 'hopeful survey' approach. However the frequency is way too low for LIGO, it's 'sweet spot' is around 200 Hz whereas this signal is about 2 mHz .... :-(
NB. I see there is potential for confusion in the discussion about the decay of the orbital period ( ~25 milliseconds per year ) and the time shift in the occultation of one of the stars by the other ( ~ 6 seconds later than expected assuming no decay ) since discovery last year. The key point is that the period of the system is around 13 minutes and so the stars make a full orbit around each other ~ 41000 times each year. The decay rate means that a single orbit at the end of a twelve month period is going to be 25 milliseconds longer than one 12 months prior; but all those orbits in between will be longer to some intermediate degree ( I think one of the comments, and their paper, indicates it varies quadratically ). Think of it like a really long NASCAR race ( 41000 laps ); if your car keeps slowing ( worsening lap times ) then you will progressively fall behind, ever so slightly with each passing lap, so that 6 seconds is ~ 1% of a lap from where you would have been if the car had kept pace.
Actually I'm trying to get my head around a dual star system with a 13 minute orbital period!
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Hello All, As a kid I
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Hello All,
As a kid I remember sitting with my mother and father in front of the TV and watching launches to the
moon via Apollo. This early exposure to science has stuck with me and I continue to seek out what makes things work and ask many questions.
Now that I am retired as a DEA Special Agent, I have been
able to make time for my love of science to include participating
in the Einstein@Home projects.
The reason I am posting this is to inform everyone about a video concerning the LISA project and how
it proposes to detect gravitational waves from space. The video is found at
http://www.elisa-ngo.org/resources/videos/video-lisa-laser-interferometer-space-antenna
It basically shows how three instruments will be ejected from its rocket carrier, and then align via laser
into a hugh triangle. The instruments will maintain alignment from the lasers.
This space created by the lasers will be able to detect gravitational waves with the possiblity of even detecting the Big Bang.
THis is a very simplistic explaination, but regardless the video is worth a view and would be a great
science project for any science fair.
Best to all the Amateur Scientists like me and a big Cheer to the participating Scientists on the projects.
Brad Lowe
KA4AQL
Kodak, TN; USA
I think that the LISA project
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I think that the LISA project has been abandoned first by NASA and then by ESA for financial reasons.
Tullio
Hallo Tullio! RE: I
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Hallo Tullio!
It´s right, the NASA endend this project, but ESA shifted at may 2nd the final decision over the NGO, New Gravitaional wave Observatory, to a later date, as the neccessary technology is not readily developed today. See near end. So it´s still alife, and the test mission LISA Pathfinder will start in 2014.
My opinion about this: It´s to important for science and technology to become canceled. Some time it will fly!
Kind regards and happy crunching
Martin
Hallo! Here is a link to the
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Hallo!
Here is a link to the homepage of eLISA/NGO. At the lower end of this site you find a link to a great paper, which can be downloaded.
Here the abstract:
eLISA: Astrophysics and cosmology in the millihertz regime
Pau Amaro-Seoane et all
(Submitted on 17 Jan 2012)
This document introduces the exciting and fundamentally new science and astronomy that the European New Gravitational Wave Observatory (NGO) mission (derived from the previous LISA proposal) will deliver. The mission (which we will refer to by its informal name "eLISA") will survey for the first time the low-frequency gravitational wave band (about 0.1 mHz to 1 Hz), with sufficient sensitivity to detect interesting individual astrophysical sources out to z = 15. The eLISA mission will discover and study a variety of cosmic events and systems with high sensitivity: coalescences of massive black holes binaries, brought together by galaxy mergers; mergers of earlier, less-massive black holes during the epoch of hierarchical galaxy and black-hole growth; stellar-mass black holes and compact stars in orbits just skimming the horizons of massive black holes in galactic nuclei of the present era; extremely compact white dwarf binaries in our Galaxy, a rich source of information about binary evolution and about future Type Ia supernovae; and possibly most interesting of all, the uncertain and unpredicted sources, for example relics of inflation and of the symmetry-breaking epoch directly after the Big Bang. eLISA's measurements will allow detailed studies of these signals with high signal-to-noise ratio, addressing most of the key scientific questions raised by ESA's Cosmic Vision programme in the areas of astrophysics and cosmology. They will also provide stringent tests of general relativity in the strong-field dynamical regime, which cannot be probed in any other way. This document not only describes the science but also gives an overview on the mission design and orbits.
Kind regards and happy crunching
Martin