Relativistic Journey

Relativistic Journey

Nuclear accelerators are designed to allow for the increase of mass with increasing speed; if they were not designed in this way, accelerated particles would all smash into the walls of the apparatus, and there would be little to do in experimental nuclear physiques. A speed is a distance divided by a time. Since near the velocity of light we cannot simply add speeds, as we used to doing in the workday world, the familiar notions of absolute space and absolute time – independent of your relative motion – must give way. That is why you shrink during the flight near the velocity of light and that is the reason for time dilation.

Traveling close to the speed of light you would hardly age at all, but your friends and your relatives back home would be aging at the usual rate. When you returned from your relativistic journey, what a difference there would be between your friends and you, they having aged decades, say, and you having aged hardly at all! Traveling close to the speed of light is a kind of elixir of life. Because time slows down close to the speed of light, special relativity provides us with a means of going to the stars. But is it possible, in terms of practical engineering, to travel close to the speed of light? Is a star-ship feasible?

Vision of Mars. Traveling close to the speed of light is a kind of elixir of life. Source : Colourful Portal © Elena

Today we have preliminary designs for ships to take people to the stars. None of these spacecraft is imagined to leave the Earth directly. Rather, they are constructed in Earth orbit from where they are launched on their long interstellar journeys. One of them was called Project Orion after the constellation, a reminder that the ship’s ultimate objective was the stars. Orion was designed to utilize explosions of hydrogen bombs, nuclear weapons, against an inertial plate, each explosion providing a kind of “putt-putt”, a vast nuclear motorboat in space. Orion seems entirely practical from an engineering point of view. By its very nature it would have produced vast quantities of radioactive debris, but for conscientious mission profiles only in the emptiness of interplanetary or interstellar space. Project Orion was under serious development in the United States until the signing of the international treaty that forbids the detonation of nuclear weapons in space. This seems a great pity, because the Orion starship is the best use of nuclear weapons we can think of.