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

I Time Invariance Confusion

  1. Sep 18, 2016 #1
    I understand what time invariance means but there are a few catches that I'm completely confused about: Suppose we have $$y(t)=x(\alpha t-\beta)$$ to test time invariance we shift the input then "plug" it into the output:$$x_1(t_1)=x(t-t_o)$$ so this is when I become confused; when we plug $$x_1(t_1)$$ into $$y(t)$$ we get: $$x(\alpha t-t_o-\beta)$$ instead of $$y(t)=x_1(\alpha t_1 - \beta)=x(\alpha (t-t_o) -\beta)$$ I believe there is some underling math I am unaware of; but, what is it? Any sources?
  2. jcsd
  3. Sep 18, 2016 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Time Invariance Confusion
  1. Invariance of Area (Replies: 8)

  2. Riemann invariant (Replies: 1)