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US Restarts Hunt For Gravitational Waves With Advanced LIGO
schwit1 writes: The hunt for gravitational waves began again for the Laser Interferometer Gravitational-Wave Observatory (LIGO)-the largest instrument of its kind. The restart follows a five-year-long, US $200-million project to overhaul the experiment's detectors. Many physicists believe the revamped experiment, dubbed Advanced LIGO, will be the first to find direct evidence of gravitational waves: ripples in the fabric of space-time that can be created by, among other things, a pair of neutron stars or black holes orbiting each other.
Gravitational waves were first theorized in 1916 by Albert Einstein as a consequence of his general theory of relativity, which celebrates its centennial this year.
If I remember correctly, the noise floor of the previous instrument was approximately the level of the signal they were looking for.
A better detector may help.
If I remember correctly, the noise floor of the previous instrument was approximately the level of the signal they were looking for. A better detector may help.
Indeed. It's hard to overstate the sensitivity of these instruments, or the vulnerability of these instruments to noise. To take one example, here's an ArXiv preprint that calculates that the original LIGO detectors would need to be physically shielded from tumbleweeds, since the the impact of a wind-borne tumbleweed on the building exterior (100 feet from the detector) could produce a vibrational or gravitational transient sufficient to appear to be a spurious gravitational wave signal.
~Idarubicin
Didn't the "scientists" who built the first experiment know what the noise issues were and that the first equipment couldn't find anything?
There is a range of possible intensities at a given frequency for predicted gravitational waves. The original LIGO project overlapped with potential ranges, so there was a potential possibility of seeing something. It was not built with the certain expectation it would find nothing.
This chart does a really good job of summarizing different predicted sources of gravitational waves, and the sensitivity of current and proposed detectors.
Did anyone else read the headline as "advanced lego"?
Well, not anything that moves, but things that move with a quadrupole moment. In other words, spherically and cylindrical symmetric movements do not radiate. A mass moving linearly by itself, or a sphere spinning will not radiate. However, two masses in orbit around each other will.