 This effectively makes the portal a one-way trip for any living being, and other organic objects.This limitation also made communication from the time-travelers almost impossible, making it a blind one-way trip.After the death of the inventor, his widow finds herself inundated with a steady stream of late 21st and early 22nd century misfits/outcasts begging to be allowed to escape the modern world for a chance to start over in the simplicity of the Pliocene.