Scientists not so sure of rate of expansion now

Discussion in 'Physics & Math' started by curvature, Aug 10, 2018.

  1. curvature Registered Member

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  3. curvature Registered Member

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    I have to admit, I never understood why distant lanterns would tell us anything about the current rate of expansion, since that light takes such a long time to reach us, it must be therefore telling us something about the past rather than the current day. At best, those signals tells us that expansion was large early on. Further more, the true interpretation of expansion has to be taken as slowing down because as it has been noted, galaxies that pass through a distance will be moving at a much faster rate than those that pass the same distance at a later time, suggesting the Hubble parameter is in fact decreasing in time.

    https://en.wikipedia.org/wiki/Hubble's_law
     
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  5. mwesson Registered Member

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    All I know is there is not one single human being that can explain
    Where the universe began
    Why did the universe begin
    Where did the energy that started the universe come from
    We can discuss atoms, particles, charges, light, etc. etc. but nobody can explain why or from where the energy comes from.
     
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  7. Q-reeus Valued Senior Member

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    Meaningless question in modern standard cosmological paradigm. Big bang in GR and similar theories was not an explosion into a preexisting flat spacetime void.
    No-one knows but many theorists speculate.
    Not correct, but, there is no universal agreement, so, take your pick:
    https://en.wikipedia.org/wiki/Zero-energy_universe
    http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
     
  8. RainbowSingularity Valued Senior Member

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    i am not surprised.
    expansion its self is kinda hard to pin down.
    more soo if everything you measure with is also expanding.
    red-shift was a sign something was not entirely correct.
    gravitational lensing shows there is some weird stuff going on.
    now this...
    it shows scientists have continued to be critical and scientific.
    thats good news !

    who is to say time its self is constant ?
     
  9. Michael 345 New year. PRESENT is 69 years old Valued Senior Member

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    This little Minion contends time does not exist

    Coffee moment and pack for Bali

    Please Register or Log in to view the hidden image!

     
  10. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    What's that supposed to mean?
    Incorrect. A red shift is completely consistent with an expanding universe.
    Huh? What do you think is weird about that?
    You mean to slightly different measurements of the expansion?
    You mean it is good that scientist are using the scientific method? That's not really very surprising.
    No one who is scientifically literate would say that.
     
  11. Q-reeus Valued Senior Member

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    Maybe just in a bad mood. Or justly pissed off with posters e.g. #3 above, who field opinions, get a point-by-point response, yet show no courtesy (or courage) to respond. Pathetic.
     
  12. Quantum Quack Life's a tease... Valued Senior Member

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    Yes it a common impression that those that should know better forget that they are observing ancient history and not something that is current.
     
  13. Xelasnave.1947 Valued Senior Member

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    Yes indeed.

    It could all be contracting at near the speed of light and we would not be able to observe such☺.

    A super nova could go off relatively close ( maybe only 50 to 100 light years ) and we would never see it coming... we would be toast as the light pulse hit us.

    When we say something is say 2 million light years away we actual are also saying what we look at is 2 million years ago.

    So say our closest neighbour M31 the Andromeda galaxy vanished today we would not notice it was gone for 2 million years...and when I say we that means whatever life form that is around on Earth in 2 million years if any☺

    We can see M31 with the naked eye in a dark location...so you can boast your eyes are so good that you can see upto 2 million light years in distance or that you can look back in time 2 million years...
    Alex
     
    Last edited: Dec 8, 2018

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