In article ,
Jos Bergervoet writes:
Recently in another newsgroup (nl.wetenschap) the question
came up of LIGO's sensitivity compared to the human eye.

This is a hard comparison to make. Not the least of the problems is
that LIGO measures "strain," which falls off only linearly with
distance, not with distance squared. That means improving LIGO
sensitivity by a factor of 2 increases the volume surveyed by a
factor of 8.

I suppose one could pick some distance and ask what energy release is
needed to produce a detectable signal in each case. However,
efficiency of energy conversion is also relevant. When black holes
merge, all the energy that doesn't end up in the final object goes
into gravitational waves. By contrast, a supernova emits only a tiny
fraction (about 10^-4 from unreliable memory) of its energy in
visible light.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

[[Mod. note -- Another very important difference in comparing LIGO/Virgo
sensitivity with that of any optical detector (e.g., the human eye) is
that the optical detector absorbs the indident photons, whereas LIGO/Virgo
is 99.9999...% transparent to gravitational waves. That is, only a very
tiny fraction of an incident gravitational wave's energy is transferred
to LIGO/Virgo -- the vast majority (much more than 99.999999%) passes
right through LIGO/Virgo (and right through the Earth).

One analogy I've read is that building a gravitational-wave detector
like LIGO/Virgo is like building a radio antenna out of wood. So it's
only by incredibly sophisticated optical and mechanical engineering that
LIGO/Virgo can detect gravitational waves at all.
-- jt]]