Results 1 to 9 of 9

Thread: The BA: HOW FAST IS THE UNIVERSE EXPANDING?

  1. #1
    Join Date
    May 2005
    Posts
    7,983

    The BA: HOW FAST IS THE UNIVERSE EXPANDING?

    http://www.syfy.com/syfywire/how-fas...it-and-thats-a

    The universe is expanding.

    Wow, I still love being able to write that down. It's such a wonderful, compact, simple statement, yet has implications so profound it may be decades before we understand them all. And we've known it to be true for a century already.
    A century already? Instead of "a century almost"? Don't we still have a dozen years to go?

    Is no one paying attention??
    Last edited by grapes; 2018-Feb-28 at 10:38 AM. Reason: Merged

  2. #2
    Join Date
    Feb 2003
    Location
    Depew, NY
    Posts
    11,078
    I stupidly read the comments and I can no longer think straight.
    Solfe

  3. #3
    Join Date
    Dec 2004
    Location
    UK
    Posts
    8,485
    the BA just got his time-dilation calculations wrong. This is what happens when you travel around the galaxy in a flying saucer.
    Formerly Frog march..............

  4. #4
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,237
    Quote Originally Posted by grapes View Post
    http://www.syfy.com/syfywire/how-fas...it-and-thats-a


    A century already? Instead of "a century almost"? Don't we still have a dozen years to go?
    i just read it as “nearly a century already” (the “already” just expresses surprise at the length of time). We only have 4 years till a century from Friedmann’s initial theoretical work, another 5 for Lemaître’s use of the red shift data (already more than a century old) to calculate the rate of expansion, another year for Hubble’s publication ...

    But it depends how you define “known”. I wouldn’t date that until the 1960s.

  5. #5
    Join Date
    Sep 2003
    Posts
    12,154
    Well, it was 1912 when Vesto Slipher got those galactic redshifts. I suppose we could average that in for a general date.
    We know time flies, we just can't see its wings.

  6. #6
    Join Date
    May 2005
    Posts
    7,983
    Quote Originally Posted by Solfe View Post
    I stupidly read the comments and I can no longer think straight.
    I like the one from Matthew Wilson yesterday
    The two distance units cancel (leaving a 3.086e+19 factor behind), leaving inverse seconds, which is a frequency. The expansion of the universe can be measured in Hertz! Looks like 2.3 × 10^-18 hertz, give or take. That's a frequency of about once every 70 billion years.
    And then answered by Owen Gwynne
    I'd say you've overthought this.
    The reduction of the Hubble Constant to ~2.3 e-18 s-1 is simply the inverse of the age of the universe, ~13.7 Billion years.
    So, how did Matthew come up with 70 billion? Did he just borrow the "70" from Hubble?

  7. #7
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    7,583
    if he did a frequency thing, 2pi enters and makes it 86 billion which is a hand wave around 70 billion??
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  8. #8
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,237
    Quote Originally Posted by grapes View Post
    So, how did Matthew come up with 70 billion? Did he just borrow the "70" from Hubble?
    I can't imagine. I can only think he made a mistake with his calculation.

  9. #9
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    10,237
    Quote Originally Posted by profloater View Post
    if he did a frequency thing, 2pi enters
    Only if you are expressing the frequency in radians, surely?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •