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To: Capitalism2003
Even if it were possible to go the speed of light, the human body couldn't practically take it...It would take around 15 years accelerating with 3G's of force (which is a LOT for a constant pressure) to reach the speed of light...another 12 years to slow down...12 to speed up and 12 more to slow down on the way back...50 year minimum journey and no way to communicate with earth?..not practical...unless we find a way to freeze people and forget about them for a hundred years.

Human interstellar voyages, if they ever happen at all, will not be two-way voyages of exploration, but rather one-way voyages of colonization. For exploration, robotics are definitely the way to go. As you explain, why would anyone want to spend their entire lives stuck inside a spaceship just so they could see another planet? The opportunities that go with colonization of new territory, however, will always be attractive to some people.

Since the trip will be one way, there also will be no need for the trip to be quick. Even if a habitable planet is found within about 10 - 20 l.y. or so, you will pretty much be talking about a voyage that will last at least one lifetime, maybe two. So we will be talking about a colonist setting off for a new home planet that they themselves may not live to see, and committing their children or grandchildren to this venture with no choice in the matter. Some interesting and difficult ethical questions there!

92 posted on 02/16/2003 7:55:36 PM PST by Stefan Stackhouse
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To: Stefan Stackhouse; Capitalism2003
Paradoxes.
If a spaceship were accelerated to the speed of light – taking 50 years in your example – we first have to decide “whose” 50 years. That is, as measured by someone on Earth, or by someone in the spaceship.

Let’s assume that we mean 50 years for the ship to go out and return to Earth, as measured by those on the spaceship.

One paradox is that when the spaceship returned, the people on Earth would have measured a much longer time elapsed (perhaps 100 years or longer). "Time" would run more slowly on the spaceship than on Earth. The reason for this is that (as mentioned in another post), clocks, experiences, events and sensations would "run" more slowly on the fast-moving spaceship than on Earth. (Relativity means that the speed between two objects is “relative”; so on which do clocks and events slow? The one that was accelerated slows.)

A second paradox is that neither the people on Earth nor those on the spaceship could tell which is “clocking” slower, if they could see one another. That is because of a phenomenon called Time Desynchronization, where the “clocks” at the rear-end of a fast-moving object are “ahead” of the “clocks” at the front-end of the object.

100 posted on 02/16/2003 10:55:00 PM PST by Diddley
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