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Old January 12th 19, 12:01 PM posted to sci.astro.research
Jos Bergervoet[_3_]
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Default LIGO sensitivity compared with the human eye

Recently in another newsgroup (nl.wetenschap) the question
came up of LIGO's sensitivity compared to the human eye.

a) LIGO can (easily) see a source at one billion light years
distance which emits the energy of 3 solar masses in 1 second
(like the black hole mergers!)

b) The eye can (also quite easily) see a source at 10 lightyears
distance emitting the energy of 0.1 solar mass in 10 billion
years (like some of the sun-like nearby stars, burning 10% mass
in their entire lifetime).

Comparing the energy flux received:
- In case a) source power (energy per second) is 1e19 x higher.
- 1/r^2 attenuation with distance is 1e16 x larger for a).

So it seems that LIGO receives 1000 times stronger energy flux
and therefore the eye is 1000 times more sensitive than LIGO.

Still, since we are playing with many orders of magnitude here,
the difference is remarkably small. Also the cases compared are
not the absolute sensitivity levels of the two systems, both
LIGO and the eye can see somewhat weaker signals. So the simple
estimate here might not completely settle it. Should anything
be adjusted in the comparison above?

(And if not, when will LIGO's successors surpass the eye?)

--
Jos