Time Dilation Formula / Calculator
12 points by mpclarkson 5 hours ago | 10 comments
  • roter an hour ago |
    How do you stop so you don't go whizzing past Alpha Centauri at near light speed? :)
    • dandanua 42 minutes ago |
      An intelligent alien race, living there, will be able to catch you, don't you watch sci-fi movies? The real question is from what you can get 4.13e+19 Jouls, required to reach Alpha Centauri in about 9 years of traveler's time.
      • aeve890 7 minutes ago |
        >An intelligent alien race, living there, will be able to catch you, don't you watch sci-fi movies?

        The aliens on alpha Centauri are 12 ft tall blue hunter-gatherer humanoids. Not much of a help for your parking problems.

    • tokai 31 minutes ago |
      if you can accelerate at 1g you can also decelerate at 1g
    • alhadrad 30 minutes ago |
      I was wondering about this too—it's super interesting! Did you create this? Could you add graphs showing acceleration and deceleration? Also, this might be a dumb question, but how does mass factor into the energy calculations? I would love to see graphs that include the multiple stages of travel (acceleration and deceleration) as well as the mass of various kinds of fuel required for different propulsion systems such as chemical rocket, nucular etc.
  • jvanderbot 30 minutes ago |
    Tangential, but I want to share the thought experiment that made time dilation click for me.

    We know everything (every effect, etc) has a speed-of-light limit.

    Imagine a metronome ticking out time. It ticks back and forth.

    Put the metronome on a space ship. Now slowly increase the velocity of the space ship. As the space ship speed increases, the "pendulum" weight now has more and more velocity (the space ships velocity plus the back-and-forth velocity). The sum of those velocities cannot exceed the speed of light, so as the spaceship velocity increases, the metronome will tick more slowly (||x+y||<c and x-->c, right?), until, asymptotically, the metronome cannot move along its pendulum swing b/c the spaceship is moving at c.

    (The metronome is a proxy for every chemical and physical process going on with you / your spaceship - they electro-chem-quantum-etc tick out their normal evolution, which must cease at c)

    It's a clockwork view of the universe that might not be strictly true, but it settles some cognitive dissonance so I'm clinging to it like a life raft.

    • 09thn34v 25 minutes ago |
      interesting thought experiment... am i correct in understanding that for this to apply, the pendulums plane of movement must not be perpendicular to that of the ship itself? additionally, when the pendulum swing's direction is in the opposite direction of the ship, it would still move even in the case where the ship is moving at c, correct?
      • jvanderbot 19 minutes ago |
        That's the way I think of it, yes, but I think it generalizes - during the backward swing it would "go", but when swinging toward the front of the ship it would "stop" - forever.
    • rolftheperson 16 minutes ago |
      This is not correct, I urge you to read a bit about Lorentz invariance, once you understand you will see why your statement does not make sense given special relativity is accurate.

      Lorentz invariance means the laws of physics remain the same in all inertial reference frames. Also a spaceship going 99.9999…% the speed of light.

      This leads to effects like time dilation, length contraction and the speed of light itself.

      The metronome can keep going at any speed independent on the speed of its own reference frame.

      • jvanderbot 10 minutes ago |
        Yes, and for that metronome to continue "ticking" according to the normal laws of physics the distance must shrink to accommodate the limits on speed - Length contraction.

        But, all the observable effects are the same under my "life raft" mental model: To an outside observer their time has stopped, to an inside observer it has not (I'm just thinking slowly). And the laws of physics are unchanged - as a function of time e.g., the number of clockwork steps per metronome tick.