Time machine

You might  think time-travel is just a science fictions but as far ascthe laws of physics go it's totally possible  however does not mean easy it may take a few thousand years to sort out the detials but in thoery at least  we already know how to build a time machine einstein's theory of gernal relativity says that time moves more slowly in stronger gravity so if you could something link two regions of space where gravity is different you

could travel back and forth between them to move forward or backward through time no where is gravity stronger than in vicnity of black hole so if you can hang out near as black hole time for you would move

more slowly than on earth which means in the time it takes you to have a cup of coffe empire could rise and fall at home but for this to work you to some how get from earth to the black hole instaneously recent news not with standing nothing can travel faster than light but there may be away around that gernal  relativity allows the existence of shortcuts through space time called warm holes which could allow travel to the future and the past say you set up a warm hole so that both ends start in 2011 after a year on earth only a few minute will have passed near the black hole  if you then drag the slower end back to earth time will flow at the a normal rate but will be offset by a year so you can go back in time but only as far back is when the time machine was  first build of course it's not like you can just  make a warm hole  wherever  you want you have to start with an existing one the good news is that warm holes may be popping  into and out of existence at the subatomic scale all the time they don't last very long through you need someway to pop them open and for that you need something with negative gravity as far as we know gravity caused by normal matter is always attractive but the universe may be full of stuff that works opposite to normal matter namely dark energy the energy that drives the on going expansion of the universe so yeah just find a black hole a warm hole that connects to it and prop open the tunnel so you can travel back and forth through time and space needless to say all this cosmic engineering doesno't come cheap propping open a warm hole wide enough for a human to pass through would take the enough output of thousanfs of stars it's a bit much for any immediately  foreseeable human civilzation but that's not really the point in thoery at least it's possible this of course raises all sorts of question like the grand father  paradox say you build a time machine and it lasts for gerneration and one of your grand children comes back and kills you how would that work if you were killed before your grandsons father your son was conceived and how can you  be around to come back and kill you some physicists think the many world

interpretation of quantum mechanics might resolve the issue perhaps it's your actual grand son rather some one form a slight different universe problem  solved and other say that there may be some  undiscovered law of physics that bars certain kind of time trav whatever the cause as it stands now while time travel may be physically possible it's definitely unfeasible but give it a few thousand years we can't know what the future holds at  least for now