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

  1. #1
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    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
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    I stupidly read the comments and I can no longer think straight.
    Solfe

  3. #3
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    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.

    Newscaster: ... But I've just had a report that a representative of Disaster Area met with the environmentalists this morning and had them all shot, so now nothing stands in the way of the concert going ahead this afternoon on this beautiful sunny day.

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    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.

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    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.

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    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
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    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.
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    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.

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    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?

  10. #10
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    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?

    Is no one paying attention??

    A ''universe still expanding'' may be a compact statement, but it much more poetic to say

    ''the big bang it still happening.''

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