3 ms·

For me, the more amazing thing is that we are able to detect 2 neutron stars merging from 130 million light years away. Just curious how sensitive these instrum

by vaidhy 6y ago

For me, the more amazing thing is that we are able to detect 2 neutron stars merging from 130 million light years away. Just curious how sensitive these instruments need to be and our ability pick signals from the noise.

pinko 6y ago
Sensitive enough to detect a change in the relative length of two 4km-long arms equivalent to less than 1/10,000th the width of a proton. And we distinguish signals from noise via a few different approaches, but our flagship search relies on matched filtering against simulated waveforms, and requiring the same signal to be coincident in time across multiple, geographically-distant detectors for which very few noise sources are correlated.
gbh444g 6y ago
A somewhat unrelated note: the proportion between Earth and Milky Way diameters is (100 trillions) the same as the proportion between a human body and a large atom nucleus. We are galaxy sized objects in some sense.
magicalhippo 6y ago
Sensitive enough that the randomness in the photon pressure on the 40kg mirrors is a source of noise they have to contend with[1]: First, we observe that [quantum radiation pressure noise] contributes to the motion of the kilogram-scale mirrors of LIGO. This observation is also made in the Advanced Virgo GW detector. It is remarkable that quantum vacuum fluctuations can influence the motion of these macroscopic, human-scale objects, and that the effect is measured. This is quantum mechanics at its experimentally most macroscopic scale. There's some great info in this[2] paper about the detector, sensitivity and performance of Advanced LIGO. And yeah it blows my mind every time I think about it. [1]: https://arxiv.org/abs/2002.01519 https://arxiv.org/abs/2002.01519 [2]: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.062003 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.0...

by vaidhy 6y ago

pinko 6y ago

Sensitive enough to detect a change in the relative length of two 4km-long arms equivalent to less than 1/10,000th the width of a proton. And we distinguish signals from noise via a few different approaches, but our flagship search relies on matched filtering against simulated waveforms, and requiring the same signal to be coincident in time across multiple, geographically-distant detectors for which very few noise sources are correlated.

gbh444g 6y ago

A somewhat unrelated note: the proportion between Earth and Milky Way diameters is (100 trillions) the same as the proportion between a human body and a large atom nucleus. We are galaxy sized objects in some sense.

magicalhippo 6y ago

Sensitive enough that the randomness in the photon pressure on the 40kg mirrors is a source of noise they have to contend with[1]: First, we observe that [quantum radiation pressure noise] contributes to the motion of the kilogram-scale mirrors of LIGO. This observation is also made in the Advanced Virgo GW detector. It is remarkable that quantum vacuum fluctuations can influence the motion of these macroscopic, human-scale objects, and that the effect is measured. This is quantum mechanics at its experimentally most macroscopic scale. There's some great info in this[2] paper about the detector, sensitivity and performance of Advanced LIGO. And yeah it blows my mind every time I think about it. [1]: https://arxiv.org/abs/2002.01519 https://arxiv.org/abs/2002.01519 [2]: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.062003 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.0...