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You can't aim our current grav wave detectors. In a very simplified form, it's two very long tubes with laser in it, you aren't pointing these buildings like yo

You can't aim our current grav wave detectors. In a very simplified form, it's two very long tubes with laser in it, you aren't pointing these buildings like you could do with even very large telescopes. The detectors have different sensitivity depending on the direction of the waves, so if a wave comes from a "bad" direction (perpendicular to both arms, e.g. directly from above), a particular detector might not detect anything, even if the wave is strong. This is why (amongst many other reasons) it's important to have multiple detectors around the world (e.g LIGO has two locations in the US, you also have Virgo in Italy, and they do collaborate), this way you can assure in theory that you can "see" every wave, no matter which direction it's coming from. (AFAIK).

throwawaymaths 2y ago
Having only two detectors was always a sketchy affair given the tremendous amount of filtering done by the teams. Now with three detectors, if the correlataed event count between pairs of detectors doesn't diminish from one detector events with the same ratio as from 2-3 detectors (high school statistics), then we will know that event detection is real.
pwatsonwailes 2y ago
Pretty spot on.
simcop2387 2y ago
> The detectors have different sensitivity depending on the direction of the waves, so if a wave comes from a "bad" direction (perpendicular to both arms, e.g. directly from above), a particular detector might not detect anything, even if the wave is strong. Unless there's such a thing as polarized gravitational waves, https://www.ligo.org/science/Publication-O1StochNonGR/ https://www.ligo.org/science/Publication-O1StochNonGR/ which might exist but are hard to discern with current detectors from what I understand. It'd be really cool to learn that there's such a thing as vector and scalar polarized gravitional waves.
tonynator 2y ago
> it's important to have multiple detectors around the world Or realllly tall detectors.

throwawaymaths 2y ago

Having only two detectors was always a sketchy affair given the tremendous amount of filtering done by the teams. Now with three detectors, if the correlataed event count between pairs of detectors doesn't diminish from one detector events with the same ratio as from 2-3 detectors (high school statistics), then we will know that event detection is real.

pwatsonwailes 2y ago

Pretty spot on.

simcop2387 2y ago

> The detectors have different sensitivity depending on the direction of the waves, so if a wave comes from a "bad" direction (perpendicular to both arms, e.g. directly from above), a particular detector might not detect anything, even if the wave is strong. Unless there's such a thing as polarized gravitational waves, https://www.ligo.org/science/Publication-O1StochNonGR/ https://www.ligo.org/science/Publication-O1StochNonGR/ which might exist but are hard to discern with current detectors from what I understand. It'd be really cool to learn that there's such a thing as vector and scalar polarized gravitional waves.

tonynator 2y ago

> it's important to have multiple detectors around the world Or realllly tall detectors.