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

Explaining to a layperson

  1. Oct 26, 2009 #1
    How would you explain the Theory of Relativity to someone in non-mathematical, everyday language?
     
  2. jcsd
  3. Oct 26, 2009 #2
    going in circles is the same as being on a spaceship that´s speeding up
     
  4. Oct 26, 2009 #3
    First I would learn it as a layperson...
     
  5. Oct 26, 2009 #4

    DavidSnider

    User Avatar
    Gold Member

    Cosmos Part 8:
    http://video.google.com/videoplay?docid=6004920772385548361&ei=GxnmSuOkNYy5lQeVz5Ee&q=cosmos+part+8&hl=en [Broken]
     
    Last edited by a moderator: May 4, 2017
  6. Oct 26, 2009 #5
    I hope you mean the "special relativity"..

    I'd start with the basic postulates and have her/him accept those

    (1) speed of light is constant for all non-accelerating observers contrasting everyday classical relativity...
    (2) All physical laws are equivalent for non-accelerating observers.

    You can even skip (2) in the beginning.
    Then contrast (1) by giving an example: You run with 5 mi/h and a car passes by 10 mi/h (same direction) you'd "conclude" that it travels by 5 mi/h in the same direction. Have her/him accept it for a fact that with light your observation is always c!

    Then the rest is easy: Two observers. One in a train, other on the ground. Put a mirror in the train (vertical), and the observers measure different lengths traveled by light, yet they observe the same speed of light. Then obviously their clocks must be running differently! Now you can easily jump to time dilation and the twin paradox (not mentioning how the paradox arises, or is resolved because they involve more subtle points). But that should be enough.

    Voila!
     
    Last edited: Oct 26, 2009
  7. Oct 26, 2009 #6
    Einstein's Relativity which you can find at any bookstore.

    I explained it to my little sister( 8th grade, but smart) starting with this.

    Me: Let us say you were racing a cheetah, you are going 12 mile/hr and he is going at 32 miles an hour, how fast is does he LOOK LIKE he's moving to you.

    Her: What do you mean?

    Me: If you and the cheetah are moving at the same direction, it looks like he is going slow...

    Her: Oh! 20 miles an hour!

    Me: Good! How did you obtain that

    Her: I subtracted.

    Me: Good, this is known as Galilean Relativity. Which means if you are moving and another object was moving, you would subtract your speed form the object's speed to obtain how fast the object LOOKS LIKE it is moving. This is known as relative speed.

    Her: Mmhhhhmmm..... I get it.

    Me: What about a beam of light? Let us say that light moves at c miles an hour, where c is just a positive number. And you moving at c-1 miles an hour, what is the relative motion of light.

    Her: *thinks about it* one mile an hour?

    Me: According to Galilean relativity, yes, you are correct. However, scientific experimentation done over a hundred years ago surprisingly found that the speed of light's relative speed is always c, no matter how fast you are moving.

    Her: I'm confused, that makes no sense.

    Me: It didn't to the scientists ,either, until Albert Einstein discovered that Galilean relativity is wrong and only worked approximately when your and the object's speed is far less than the speed of light, which is about 670 million miles an hour. He found another principal of relative speed called special relativity.
     
  8. Oct 26, 2009 #7

    jgens

    User Avatar
    Gold Member

    "When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute and it's longer than any hour. That's relativity."

    ~Albert Einstein

    Edit: I realize that this quote isn't really pertinent but it's the first thing that came to mind when I read your question.
     
  9. Oct 26, 2009 #8
    When I have the opportunity to do so, I explain using Pinu7's approach. I also point out that speed is distance divided by time. The only way that the speed of light can be the same for all observers is if distance, or time, or both get distorted somehow.
     
  10. Oct 26, 2009 #9
    Great replies so far, and I like the way the explanations are becoming easier and easier to explain so far. I may have some luck with my grandmother yet. :smile:
     
  11. Oct 26, 2009 #10
    Try using dollars.
     
  12. Nov 24, 2009 #11
    Me: What about a beam of light? Let us say that light moves at c miles an hour, where c is just a positive number. And you moving at c-1 miles an hour, what is the relative motion of light.

    Her: *thinks about it* one mile an hour?

    Me: According to Galilean relativity, yes, you are correct. However, scientific experimentation done over a hundred years ago surprisingly found that the speed of light's relative speed is always c, no matter how fast you are moving.

    Her: I'm confused, that makes no sense.

    Me: It didn't to the scientists ,either, until Albert Einstein discovered that Galilean relativity is wrong and only worked approximately when your and the object's speed is far less than the speed of light, which is about 670 million miles an hour. He found another principal of relative speed called special relativity.[/QUOTE]


    what was the experiment conducted and who conducted it. i would like to explore this in more detail. very interesting
     
  13. Nov 24, 2009 #12

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

  14. Nov 24, 2009 #13

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    I see where you're going with this:

    you%20do%20not%20understand.jpg
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Explaining to a layperson
  1. Please Explain (Replies: 7)

Loading...