I have a problem, in a story I'm thinking about writing, it is very far off into the future (let's say around 7000 AD if there has to be a number) and mankind has basically moved on to it's next stage and has begun exploring the far out universe. For some mysterious reason our solar system has been "locked" and mankind can no longer get into the solar system where our species was born and many have tried and failed but it seems it can only be "opened" from the inside.
I have been thinking about this for a while and I cannot find out how I can lock my solar system. And by lock I mean no ships, people or objects can enter into the solar system. Or if they try to enter they will be destroyed/severely damaged. Also it doesn't have to be impossible just extremely difficult.
One of the reasons this is so difficult is because I do not want to just use a force field encapsulating the solar system. Or some sort of massive ship blockade that shoots anyone who comes near. I don't want to limit my answers at all but these both seem like they would be very easy to eventually get past and difficult to maintain.
If anyone has any suggestions on how I could accomplish this I would be extremely grateful. (Also no magic. Sorry.) You can use any known technology or theories to help answer this.
My original question was put on hold because I was unclear so here are the specifics.
The human race over the next 3000 years has become extremely advanced using genetic engineering to become biologically immortal, created incredible strong and light materials never before conceived, wormholes, FTL travel, etc. And the human race has spread throughout the universe using this technology.
Over the next 1000 years there is an intergalactic war. The human race is split into "tribes" most experience a devolution period because of their genetic enhancements they evolve much faster to adapt to the planets they live on. And lose a large amount of the technological knowledge they once had and basically have to start over.
Around 7000 AD some humans have found evidence that they came from earth. And they go out and try to get to our solar system. Unfortunately during the 3000 years when humans experienced there perfect evolution something has been set in place to stop anything from entering our solar system by the perfect humans.
I need that something to leave the solar system mostly intact/unharmed and keep anything from entering the solar system.