First, let’s talk
about Newtonian gravity and Einstein’s gravity.
defines that gravity as the attractive attraction between two objects with
mass. But Einstein explains gravity as a distortion of space caused by the
matter with mass. In other words, Newton states that there is only the
attractive force between two objects without the spatial distortion around the
objects. But Einstein states that a massive object makes spatial distortion
which is defined as gravity.
1. Newton and Einstein's Definition of Gravity
Light deflection and gravitational lens effect
Einstein predicted that the light path
is changed by spatial distortion caused by matter such as the sun based on
general relativity, as shown in figure 2. And, Arthur Eddington proved
experimentally Einstein's gravity theory was correct by confirming that the
observed position were different from the actual position because the light
passing near the sun was deflected.
2. Light deflection by the sun
In this way, light deflection by the gravity
of a massive matter is called Gravitational lens effect and it can be seen
during astronomical observation. For example, as shown in figure 3, light
emitted from distant galaxy are bent by massive quasar's gravity and observer
on earth sees it as if there is a red ring around the quasar.
3. Gravitational lens effect
SungSoo Kim Ph.D
* Next week’s topic: Effects of Artificial Lighting on Birds
You can find "Interesting Story about Light Science” series on the link below.