According to the scripture, when and how is the world destroyed? There is a lot of talk about the end times. But where and when in the scripture does it recount the world actually being destroyed? In the end of John's Revelation we have the new heaven and earth, and at the beginning the old. More specifically, at what event and by what means are the old heavens and earth destroyed?
If I am understanding St. Paul correctly, he's telling us that there is no way to know when this will happen -- that indeed the angels don't even know -- and that our preoccupation with it is of no consequence if we are not ready to meet and be judged by God on that day.

The following is based on 1 Thessalonians chapter 5:


  "Of the times and moments. That is, of the day of judgment, of the end
  of the world, of the destruction of Jerusalem. It is enough to know
  the time is uncertain, and that death cometh as a thief in the night.
  (Witham) --- When the judgment shall take place the Angels themselves
  do not know. Perhaps St. Paul, when wrapt up to the third heaven, may
  have learnt something on this subject; for he was told many things
  which he could not announce to man; therefore, he says, I need not
  write to you: it is unnecessary for us to know it. (Calmet)"


The second epistle of St. Peter does suggest fire though:

2 Peter 3:10: But the day of the Lord shall come as a thief, in which the heavens shall pass away with great violence, and the elements shall be melted with heat, and the earth, and the works that are in it, shall be burnt up.

Some commentary on this:


  The heavens, &amp;c. He puts the faithful in mind not to regard these
  profane scoffers, but to be convinced of the truths revealed, and that
  the world shall be destroyed a second time by fire. Reflect that the
  time of this life, and all the time that this world shall last, is
  nothing to eternity, which has no parts, no beginning, nor end; so
  that in the sight of God, who is eternal, a thousand years are no more
  to be regarded than one day, or one moment. The long time that hath
  hitherto passed, must not make you think that God is slack as to his
  promises, or that they shall not infallibly come to pass at the time
  and moment appointed by his divine providence. God's infinite mercy,
  and his love for mankind, bears patiently with the provocations of
  blind and unthinking sinners, not willing that any of them should
  perish, but that they should return to him by a sincere repentance and
  true penance, and be saved. But watch always, according to the
  repeated admonition of our blessed Redeemer. (Mark xiii. 37. &amp;c.) For
  both the day of your death, and the day of the Lord to judge the
  world, will come like a thief, &amp;c. (Witham)