The Peloran made Contact with us a century before the main story in Jack of Harts. Aliens are normal and accepted in Jack’s worldview, and so is the effective immortality of humanity. He wasn’t even alive when the Peloran made their Treatments available to anybody who wanted them for free. They are like a superboost to the human immune and repair systems that massively slows down the aging process. Jack does not remember a time when people died of old age. It is a foreign concept to him. Yes, he has read about it. He knows it used to happen. Just like people use to get the flu. Or cancer. Or small pox. The Black Death. Addiction to drugs. Overweight. Underweight. Diabetes. They are all artifacts of the past, eliminated by a combination of Alien and Human medical sciences that have literally changed the world. Jack is healthy, and he has every expectation that those around him will also be healthy until the day they die.