how do you know the world will end someday

Question: how do you know the world will end someday
- Keywords:
  end of the world,
  future
Asked by cberry to Hitesh, Hywel, Mae, Nik, Tiffany on 14 Jun 2012.
- Tiffany Taylor answered on 14 Jun 2012:
  
  Because some clever physicists have worked out the age of the sun and how long it can live for before it’s burned up everything it is burning. When there’s not much left to burn it will start to swell, and destroy a lot of near by planets (including ours), and finally it will go out. But don’t you worry, they don’t think this will happen for about another 5 billion years.
- Hitesh Dave answered on 20 Jun 2012:
  
  I dont think it will end any time…Yes. ofcourse the way the moon and sky position is now..it might change the way it looks but I personally believe its not going to end anytime..

Question: how do you know the world will end someday