I came up with a way to check whether time travel is possible. Everything is very simple – you collect a lot of money and hire a staff of scientists. You write the money of the years and so for 1000 ahead and leave a will to your company so that, when the time machine is created, its drawings are delivered in that same day to that room in the evening. If at the end of the day the drawings are not delivered, you can shut down the company.