Why are rapid fluctuations in an active galaxy's luminosity ...

[codyclark]

Why are rapid fluctuations in an active galaxy's luminosity evidence for a supermassive black hole?
 
  What will be an ideal response?

Question 2

Explain how the structure of the atom creates binding energy, and what limits there are on the amount of binding energy an electron can have.
 
  What will be an ideal response?

[Cnarkel]

Answer to Question 1

Rapid fluctuations must come from a very small source. The only object that can be luminous and massive enough within the small spaces implied is a black hole.

Answer to Question 2

The Coulomb force is an attractive force between oppositely charged particles. The positive protons in the nucleus attract the negative electrons in the electron cloud. In order to overcome this force and remove the electron from the atom, energy must be added to counteract the Coulomb force. This energy is called the binding energy, since it is the amount of energy that binds the electron to the nucleus.

Quantum mechanics demands that the electron can only occupy certain permitted orbits or energy levels, and cannot exist between them. Each of these represents a different amount of binding energy. The lowest energy level is termed the ground state.

For each atom, the electron will only be able to have the uniquely specific energy values represented by that atom's unique pattern of energy levels.