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  • Pulsar Timing Arrays detect evidence of possibly new physics

    From jillery@21:1/5 to All on Mon Jul 17 10:31:55 2023
    The following is a link to a 24-minute Youtube video, where Dr. Becky
    describes pulsars, pulsar timing arrays, and evidence from them for gravitational waves decades long:

    https://www.youtube.com/watch?v=BUmJxZ7PQzw

    Short version: pulsars are a special class of stellar objects. Their
    rotation is extremely regular and and can be very rapid, up to 1000
    rpm, and sweep high-energy beams of detectable EMR throughout the
    galaxy.

    There are several phenomena which can alter their rotation and so
    their signal periodicity ex. stellar quakes. GR predicts that
    gravitational waves would temporarily alter their observed rate.
    Scientists have observed hundreds of pulsars over decades, long enough
    to correlate changes among them, and by so doing infer that
    gravitational waves had swept through the pulsar array and changed the
    pattern.

    One cause of decades-long gravitational waves would be supermassive
    black holes orbiting each other at multi-light-year distances, but
    there are other possibilities, ex. gravitational phenomena from before
    the CMB.

    --
    You're entitled to your own opinions.
    You're not entitled to your own facts.

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From jillery@21:1/5 to All on Wed Jul 26 21:44:26 2023
    On Mon, 17 Jul 2023 10:31:55 -0400, jillery <69jpil69@gmail.com>
    wrote:

    The following is a link to a 24-minute Youtube video, where Dr. Becky >describes pulsars, pulsar timing arrays, and evidence from them for >gravitational waves decades long:

    https://www.youtube.com/watch?v=BUmJxZ7PQzw

    Short version: pulsars are a special class of stellar objects. Their >rotation is extremely regular and and can be very rapid, up to 1000
    rpm, and sweep high-energy beams of detectable EMR throughout the
    galaxy.

    There are several phenomena which can alter their rotation and so
    their signal periodicity ex. stellar quakes. GR predicts that
    gravitational waves would temporarily alter their observed rate.
    Scientists have observed hundreds of pulsars over decades, long enough
    to correlate changes among them, and by so doing infer that
    gravitational waves had swept through the pulsar array and changed the >pattern.

    One cause of decades-long gravitational waves would be supermassive
    black holes orbiting each other at multi-light-year distances, but
    there are other possibilities, ex. gravitational phenomena from before
    the CMB.


    The following is a link to a 17-minute video from PBS Spacetime on the
    same subject as above:

    <https://www.youtube.com/watch?v=byN4S8WDPt8>

    From the transcript:
    **********************************
    @11:22
    let's pause for a moment to appreciate how crazy this achievement
    really is. Remember that we started with a simple thought experiment
    about the experience of someone falling off a roof. That "what if"
    scenario led us all the way to actual observation of
    Galactic scale SpaceTime ripples.
    **********************************

    But apparently nary a ripple in T.O.


    --
    You're entitled to your own opinions.
    You're not entitled to your own facts.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)