[granos]

Imagine a giant cube around the entire earth that touches in 6 places -- one on each cube face. Pick 3 faces and place a detector where each touches the earth -- on the surface. You can rotate the detectors around on the surface so that you get an arm in each axis relative to the center of the earth.

[magicalhippo]

Right, that's basically what they do now by building multiple detector facilities. I was talking about multiple arms in a single location.

[jessriedel]

This isn't necessary since the wave looks the same at all locations on Earth.

[magicalhippo]

It can come directly from above, in which case you can't discriminate between from above or from below as it'll hit all arms at the same time if they're at a single location. You'd also have poor directionality.

[thewakalix]

Wouldn't the Spacetime Cube be just as vulnerable to the perpendicularity problem, though? It might have more sensitivity in near-perpendicular cases, but that's simply because there are more detectors.

[magicalhippo]

As mentioned, if multiple detectors are not spatially coinciding, then one can use the time difference between detection events as well.

[wizardforhire]

A time cube...