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

Time to take a little test

  1. Mar 3, 2005 #1
    I just read the newest Scientific American. there is an article in it about 6 misconceptions about the big bang. let's see how you do? Can you answer the following 7 questions?
    1)What kind of explosion was the big bang?
    a. The big bang was like a bomb going off at a certain location in previously empty space.
    b. it was an explosion of space itself

    2)Can galaxies recede faster than light?
    a. Sure they can special relativity does not apply to recession velocity.
    b. of course not, special relativity forbids that.

    3)Can we see galaxies receding faster than light?
    a. no the light from those galaxies never reaches us
    b. yes because the expansion rate changes over time

    4)Why is there a cosmic redshift?
    a.because space stretches all light waves as they propagate.
    b. because receding galaxies are moving and exhibit a Doppler shift.

    5)how large is the observable universe
    a.the universe is 14 billion years old so has a radius of 14 billion light years
    b. because space is expanding the observable universe has a radius about 3 times larger than 14 billion light years.

    6)Do objects inside the universe expand too?
    a. yes
    b. no, the universe grows but coherent objects inside it do not.

    7) Why won't Moonbear give me the time of day?
    a. she doesn't have a watch
    b. she has something called good taste

    I'll post the answers in a few minutes unless I forget, in which case someone come find me in General discussion and remind me.
  2. jcsd
  3. Mar 3, 2005 #2


    User Avatar
    Science Advisor
    Gold Member

    my guesses:
    1. b
    2. a
    3. a
    4. b
    5. a
    6. b
    7. a who's Moonbear?
  4. Mar 3, 2005 #3
    you need to spend more time in biology and General Discussion, Moonbear is a goddess who loves me but won't admit it.
    the correct answers are:
    7.c trick question, she will give me the time of day as soon as I wear her down enough with dumb little flirtatious things like this one.
  5. Mar 3, 2005 #4


    User Avatar
    Science Advisor
    Gold Member

    3 out of 6 (not including the trick question). I could have randomly guessed and done as well! I guess Scientific American proved their point about misconceptions.
  6. Mar 3, 2005 #5
    Got them all, yay! But then you'd hope an astro/physics major would...
  7. Mar 4, 2005 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    All of them, really? Even #7? :biggrin:

    I got 5 out of the first 6 (woo hoo, I must be learning something around here), but I don't agree with the answer given for #7. My watch works just fine. :devil: (sorry tony, you still got that one wrong, but I don't think it was really in the Sci Am quiz :wink:)
  8. Mar 4, 2005 #7
    Its strange, not only did Lineweaver not consider tribdog's question 7, he also didn't consider:

    8) If a galaxy is receding from us at twice the speed of light and a jet is ejected from the galaxy in our direction at 0.99c wrt the galaxy, will we see the jet as redshifted or blueshifted.

    and maybe the answer to Q7 is that Moonbear doesn't agree with the time coordinate in tribdog's coordinate system - just as I don't agree with Lineweaver's.
    Last edited: Mar 4, 2005
  9. Mar 16, 2005 #8
    Thank you for this thread.

    It seems like the Doppler Shift is constantly inserted as a pedagogical tool, but it turns out it really only served to confuse me. I suppose the confusion was good if it lead me to investigate, though. :)
  10. Mar 16, 2005 #9
    6 out of 7.....lol I chose A for 7
  11. Mar 16, 2005 #10
    I did ok myself, for not knowing squat about the universe. :smile:

    Andromeda, should hope you would get them all...:grumbles: fate of the world in astro/physics people...should hope you know what your doing...:biggrin: Just Kidding!
  12. Mar 16, 2005 #11
    Yep I often have fond hopes that we know what we're doing as well. :biggrin:
    Now if only we can get this miles to kilometers thing down on our Mars rovers...
  13. Mar 17, 2005 #12
    I hope your Mars rovers aren't a mix of standard and metric parts...

    :grumbles: we're doomed...good luck finding people to volunteer to go live on Mars...hehehe...jk:biggrin:
  14. Mar 23, 2005 #13


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Why not? Mayhap you don't like GR?
  15. Mar 23, 2005 #14
    Too bad, I can't take the test! I've read the article before.
    Here it is if you're interested: Misconceptions about the Big Bang
    Last edited by a moderator: Mar 23, 2005
  16. Mar 27, 2005 #15
    i got them all *Fibonacci gets blood rush to his head as it fills with ego* two minutes later Fibonacci misses simple math question, ego goes away. Fibonacci, filled with sadness because of his mistake, kills small insects.

    Just Kidding, please don't call the EPA on me

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook