Want to have a time machine? study history.
The world runs in circles, it repeats itself and corrects in interval. Whatever happened before, will happen in future for sure. Time is the barrier.
From the cosmic disaster which vanished dinosaurs and made them chickens. To the rise of Mammals. The Ice Age, The Great Flood, Historic pole shifts, meteorites endangering Earth’s atmosphere, just makes us realise every cycle has an end. And we are participants in one of those circles.