But, time travelling into the future might be possible. If you want to travel into the future, you just have to stop your body from getting older. You have to freeze your body in time.
Some scientists study animals that freeze over the winter.
Humans can't safely freeze because our blood would turn into ice and tear our veins. We just need to find out how other animals survive freezing. Then we can freeze ourselves and thaw out again in the future. But, time travelling into the future may be a different story. You can travel into the future if you can stop your body from aging.