4 year old terrified about the end of the universe

My little Mr 4 loves watching science videos on YouTube and for the most part I encourage it. He's really interested in space, dinosaurs, evolution, you name it. One of his favourite channels is Kurzgesagt – In a Nutshell - you may have come across their brilliantly animated videos. Here is a great one about the immune system : https://www.youtube.com/watch?v=zQGOcOUBi6s and one about human evolution : https://www.youtube.com/watch?v=dGiQaabX3_oLately he's been watching this one about Red Dwarf stars and it goes into what's going to happen at the end of the universe: https://www.youtube.com/watch?v=LS-VPyLaJFMHe's watched it a few times, but the last few times after he watched it he started asking me questions about it.He starts off innocuously, "Is the universe really going to end in 5 billion years?", "Are all the stars going to go out?", "What will happen to the earth and all the planets?". He then bursts into tears and starts getting really upset about this event that is over 5 billion years away. He's got no understanding of the passage of time and thinks this is something we'll have to deal with.He's also started randomly thinking about it and will start asking those same questions when we are out, or in the bath, and inevitably burst into tears.Tonight I tried to tell him that by then maybe humans would be able to fly to a new planet to live on. That made him more upset because "we don't know how to make a spaceship!".I'm reluctant to make to clear that we'll all be dead and gone by then, that is something else he gets upset about.He's always asking me "Is it real or made up" because I try to make that distinction when we are watching shows together. I could easily lie and say it's made up but I'd feel bad about not being truthful with him.Otherwise is there a clever way to get a 4 year old to understand actually how far away this is going to be?Anyone else had to deal with a 4 year old prophet of doom? via /r/Parenting http://ift.tt/2xTu7j2