Yes the world will end… I like to think about the end of the world as when all life on the planet is dead. This is expected to happen in 500 million years, which is quite soon – it means that if the earth was a human, she would be around 80 years old (assuming she would live till 100). So be gentle with her!
Life will die because the sun will make it too hot. Throughout the earth’s life, the sun has been getting hotter and hotter. Life has been able to cope by making changes to adapt. But at some point, (500million years away) it is estimated that the sun will just be too hot. However, with clever people like us around, we might be able to prolong the life of the earth. I guess neither you nor I will be around to see that happen, but I think you will agree that looking after the earth now is something that is worth doing.