If a spear is jabbed exactly at that place where the fish appears in water, the fish is not killed. give reason

Source:

ARC Centre of Excellence in Coral Reef Studies

Summary:

Fish are not as dumb as people sometimes think. Marine scientists have found that fish that are regularly hunted with spearguns are much more wary and keep their distance from fishers. In investigating the effects of marine areas closed to fishing by customary laws, an international team of researchers working in the Pacific found that fish exposed to speargun fishing take flight much earlier when a diver approaches compared with those living in protected zones.

The fish is not killed due to the Refraction (bending) of light.

Explanation:

The light experiences a phenomenon called Refraction that is the change of path or bending. As light travels from denser medium (water) to a less dense medium (air), its speed increases to some extent. Due to this change in speed of light, the path of the light changes. The observer sees the image of fish in the water formed by these bent rays of light coming off the fish which is at a different location and he/she jabs the spear at that location. However, as it is not the real location of fish but how it appears due to refraction, the spear is jabbed at a wrong location and the fish is not killed.    

answer; (arch); good luck

3. dark matter

empty space could also be a simple vacuum