I know it was from a couple of days ago and it's described as a 'tiny' possibility in astronomical terms in about a billion years time, but I've only just read it.
Anyway, if the planet Earth in a billion years had been totally stripped of minerals and the like due to us having extracted them all before moving to another universe to live on Earth 2. Would the melded planets then have the effect of re-creating a new planet as they were when they were created the first time around with a liquid iron core and eventually re-evolve again with oceans and an atmosphere to support an early life to again evolve into us again, and are we here on the first time or 5th or 6th time?
Wow! That is really something to bend your mind around...
There's a degree of mystery about how our planet got its water in the first place. Think about it - where did all that water (approximately 326 million trillion gallons of it) come from in the first place?
There are several theories, one of which is that the water - 97% of which is saline, and contained in the oceans - came from millions and millions of comets that bombarded the earth in the early stages of its life. Comets are composed of ice, and the accumulation of all that comet ice is what provided our planet with its water. It's a theory, and there are others, but the truth is, nobody really knows for sure.
Whatever the origin, the fact that the water is here lead to the evolution of life, so we can be grateful. It would be unlikely to happen again, however, so are we here for the first time? If by that you mean are we the first homo sapiens to have evolved on our planet, the answer is yes.