##
The Relativistic Rocket

This applet lets you plan how long a trip will take on a rocket that
travels near the speed of light. You type the distance of the trip
(measured in light years) and the acceleration of the rocket (measured
as a multiple of Earth's gravity). The rocket will accelerate at that
rate for half of the trip, then decelerate at the same rate for the second
half of the trip.
The time for the trip is measured in two ways: (1) As seen by a person
who stays behind on Earth, and (2) as measured by you on the ship.
For your convenience, space-sickness pills are available aft of the
observation lounge.

The equations for the computations came from the
Desy Web Site.
Here is what I used:

- Calculate
`d`

as the distance of **half** the trip in meters.
(Note: There are about 9.47e15 meters per light year).
- Calculate
`a`

as the acceleration in meters/sec².
(Note: The conversion is 9.81 times the acceleration measured in gravities.)
- Set
`c`

equal to the speed of light in meters/sec (which is
3.00e8).
- The total time on earth, measured in seconds is:

` 2 * sqrt( (d*d)/(c*c) + 2*d/a )`

- The total time for the voyager, measured in seconds is:

2 * (c/a) * asinh(a*time_earth/c)

(Note: `asinh`

is the inverse hyperbolic sin function, computed
in Java with the formula `Math.log(x+Math.sqrt(x*x+1))`

.