Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Minimum travel time

  1. Jul 13, 2009 #1
    I was considering this the other day, and I'm pretty sure I know the answer, but I want verification that I am not missing anything.

    Suppose you are in a rocket ship and you want to travel, say, to a star the nearest galaxy. Is there a minimum amount of time that would require?

    Since the speed of light is the ultimate barrier, a naively person familiar with the cosmic speed limit would say, yes. You have a set distance to travel and you have a maximum speed, so there is a minimum time required.

    But when you take spacial contraction into account, things change. As you accelerate, the space begins to contract. Even after the star's relative velocity begins to cap out near c, the contraction continues, down to an arbitrarily small length. And so, it should be possible to reach the star in an arbitrarily short span of your ship's proper time.

    Am I correct in this reasoning?
  2. jcsd
  3. Jul 13, 2009 #2

    George Jones

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  4. Jul 13, 2009 #3
    Sweet 8-D

    Just out of curiosity, say this journey started on Earth. As the rocket traveled away from Earth at near c, from the Earth's frame, wouldn't the space ship be contracted back to Earth as its velocity away from Earth increased? The velocity, of course, is always measured as c by the Earth's unchanging frame, so the ship's velocity will always dominate the spacial contraction. But doesn't this contraction need to be taken into account when calculating the ship's flight plan from Earth?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Minimum travel Date
B Why can't light travel faster than c? Wednesday at 1:11 PM
Einstein-Hilbert action origin Oct 18, 2015
Minimum energy to accelerate a mass? May 19, 2015
Minimum speed in the universe May 18, 2015
Maximum and minimum speed Oct 20, 2014