Zero

That sums everything up. Zero is everything and zero is nothing. Zero is a state of being. People who kill themselves frequently feel emotionally overburdened followed by a period of emotional numbness. Then they feel everything around them is the same as nothing changes, somewhat like a submarine deployment felt like to me. I must say I appreciate the US Navy and specifically nuclear submarines, because without them I do not believe I would have ever got so close to zero, so close to suicide.

Zero \Ze"ro\, n.; pl. Zerosor Zeroes. [F. z['e]ro, from Ar. [,c]afrun, [,c]ifrun, empty, a cipher. Cf. Cipher.]

• (Arith.) A cipher; nothing; naught.
• The point from which the graduation of a scale, as of a
  thermometer, commences.
  Note: Zero in the Centigrade, or Celsius thermometer, and in
  the R['e]aumur thermometer, is at the point at which
  water congeals. The zero of the Fahrenheit thermometer
  is fixed at the point at which the mercury stands when
  immersed in a mixture of snow and common salt. In
  Wedgwood's pyrometer, the zero corresponds with
  1077[deg] on the Fahrenheit scale. See Illust. of
  Thermometer.
• Fig.: The lowest point; the point of exhaustion; as, his
  patience had nearly reached zero

Webster's Revised Unabridged Dictionary (1913)

New navy nuclear power and nuclear submarines Submarines nuclear reactor operator speaks of nuclear power and nuclear submarines. Submerge into enlistment without boarding a nuclear submarine.