relativistic distance calculator

lightspeed.go

// quick back of envelope calculations for computing distance traveled (from traveler's perspective)
// when constantly accelerating at 9.8 m/s^2.
package main

import (
	"fmt"
	"math"
)

const (
	C                  = 2.998e+8 // meters per second
	SecondsPerYear     = 60.0 * 60.0 * 24.0 * 365.0
	MetersPerLightYear = 9.4607e+15
	a                  = 9.80665
)

func main() {
	yearsTraveling := 6.75
	distInMeters := relativisticDistance(SecondsPerYear * yearsTraveling)
	distInLightYears := distInMeters / MetersPerLightYear

	fmt.Printf("distance in meters: %f\n", distInMeters)
	fmt.Printf("distance in light years: %f\n", distInLightYears)
}

// https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration#Expressions_for_covered_distance_and_elapsed_time
func relativisticDistance(timeInSeconds float64) float64 {
	return C * C / a * (math.Cosh((a*timeInSeconds)/C) - 1)
}