Robert McNees

@mcnees

Professor, physicist, science communicator. Studying black holes, quantum gravity, cosmology. Tar Heel. RT = spooky action at a distance. Opinions are all mine.

Chicago, z=0
jacobi.luc.edu
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Joined June 2008
6,601 Photos and videos Photos and videos

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  1. Pinned Tweet
    24 Jul 2015

    I can't not respond to this kind of comment.

    110 replies 2,643 retweets 3,851 likes
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  2. Retweeted
    35 minutes ago

    NASA lost contact with a satellite 12 years ago. An amateur just found its signal.

    1 reply 20 retweets 46 likes
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  3. Retweeted
    5 hours ago

    A little while back I volunteered to be an 'ambasadóir' for organised by & co. Unfortunately my dad passed away during the week and so I couldn't really participate. I think this speaks to it though, would that I could write in Irish this well

    ‘The death notice won’t say “surrounded by loving family”. I wasn’t fast enough’
    2 replies 4 retweets 10 likes
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  4. 1 hour ago

    My friend wrote this beautiful piece for .

    1 reply 1 like
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  5. 3 hours ago

    Good morning.

    7 likes
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  6. 12 hours ago

    A short thread about Einstein and “gravitationswellen.”

    Albert Einstein submitted his paper “Über Gravitationswellen” in 1918. "On Gravitational Waves" corrects an important mistake in his 1916 paper and gives the correct description of gravitational waves in general relativity.
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  7. 15 hours ago

    Happy to report the 5yo found some remarkably well-preserved specimens in the La Brea Syrup Pits.

    14 likes
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  8. 16 hours ago

    If you just fave it they take money away, you monsters.

    12 likes
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  9. 17 hours ago

    Here’s an asteroid wiping out the dinosaurs, in pancake form. Since I added the hashtag, Bell will donate 5 cents to Canadian Mental Health Initiatives for every RT it gets.

    8 replies 726 retweets 541 likes
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  10. Retweeted
    17 hours ago

    every retweet this or any tweet with the hashtag gets, Bell says it will donate 5 cents to Canadian Mental Health Initiatives! so a reminder:

    4 replies 528 retweets 303 likes
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  11. 23 hours ago

    And Max Abraham noted as early as 1912 that conservation of momentum would forbid the dipole emission of gravitational waves. Indeed, gravitational waves require quadrupole sources. (Abraham's approach to gravity had its own problems, though.)

    3 likes
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  12. 23 hours ago

    Henri Poincaré, in the 1905 paper “Sur la dynamique de l' électron,” proposed that gravity was transmitted by “l'onde gravifique.” Later he would suggest that this phenomenon might affect the advance of Mercury’s perihelion.

    1 reply 5 likes
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  13. 23 hours ago

    What is not so well-known is that at least three physicists before Einstein considered gravitational waves or related phenomena: Pierre-Simon Laplace, Henri Poincaré, and Max Abraham. Laplace imagined how a finite propagation speed for gravity would impact the moon’s orbit.

    1 reply 1 retweet 9 likes
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  14. 23 hours ago

    (It wasn't until the 1957 Chapel Hill conference, organized by Cécile DeWitt-Morette, that a consensus emerged among physicists, that gravitational waves were a real phenomenon with measurable [if small] effects.)

    1 reply 10 likes
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  15. 23 hours ago

    Einstein famously doubted his own result, revisiting it multiple times and trying to poke holes in it. In 1936 he announced that he and Rosen had shown gravitational waves don’t exist. He suspected that there were singularities that signalled some sort of breakdown.

    1 reply 9 likes
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  16. Jan 31

    The first direct detection came 97 years after "Über Gravitationswellen." On February 11 of 2016, announced that gravitational waves had been detected on September 14, 2015, the result of two black holes spiraling into each other over a billion years ago.

    1 reply 1 retweet 13 likes
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  17. Jan 31

    Indirect evidence of gravitational waves was obtained 56 years later, in 1974. The decaying orbit of the binary pulsar discovered by Russell Hulse and Joseph Taylor was consistent with general relativity's prediction for the rate of energy loss due to gravitational waves.

    1 reply 1 retweet 12 likes
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  18. Jan 31

    Albert Einstein submitted his paper “Über Gravitationswellen” in 1918. "On Gravitational Waves" corrects an important mistake in his 1916 paper and gives the correct description of gravitational waves in general relativity.

    5 replies 48 retweets 107 likes
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  19. Jan 31

    Good morning.

    2 replies 12 likes
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  20. Jan 31

    But here's a photo of someone giving Ham the space chimp an apple after he was pulled from the Atlantic in 1961. Source: NASA ()

    2 likes
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  21. Jan 31

    Here's another photo of Jinx, in what appears to be the same outfit. Image: Philip Doggett

    1 reply
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