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johncarlosbaez's profile
John Carlos Baez
John Carlos Baez
John Carlos Baez
@johncarlosbaez

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John Carlos Baez

@johncarlosbaez

I do math, physics, network theory at U. C. Riverside and the Centre for Quantum Technologies in Singapore.

Riverside, CA
math.ucr.edu/home/baez/
Joined September 2016

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    John Carlos Baez‏ @johncarlosbaez Jan 12
    • Report Tweet

    John Carlos Baez Retweeted Simon Tardivel

    This simulation makes you wonder: could the Solar System be unstable? Will a planet eventually be thrown out of the Solar System? People have done a lot of work on this problem. It's hard. The Solar System is chaotic in a number of ways.... (1/n)https://twitter.com/simon_tardivel/status/1215728659010670594 …

    John Carlos Baez added,

    0:16
    Simon Tardivel @simon_tardivel
    Par exemple, prenons une jolie configuration à... 4 corps désormais ! Regardez les premiers tours, c'est joli hein... Ouais continuez à regarder... #SpoilerAlert CA VA MAL FINIR ! pic.twitter.com/rxQeBkJ2kr
    Show this thread
    9:36 AM - 12 Jan 2020
    • 637 Retweets
    • 2,038 Likes
    • Artur s.akef Murilo Menezes Orpheus Lummis James Robinson Ale Grilli Julita Juan Grau KingMinus Benjamin McCarthy
    46 replies 637 retweets 2,038 likes
      1. New conversation
      2. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        Saturn's moon Hyperion wobbles chaotically thanks to interactions with Titan. It has a "Lyapunov time" of 30 days. That is, a slight change in its rotation axis gets magnified by a factor of e after 30 days. You can't really predict what it will do a year from now. (2/n)pic.twitter.com/babmT97qm2

        4 replies 21 retweets 215 likes
        Show this thread
      3. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        Pluto's moon Nix also rotates chaotically. You could spend a day on Nix where the sun rises in the east and sets in the north! Watch the video to see how weird it is. (3/n)https://www.youtube.com/watch?reload=9&v=ZOgIsb2KjSQ …

        3 replies 37 retweets 220 likes
        Show this thread
      4. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        But what about planets? Pluto is locked in a 2:3 resonance with Neptune. Apparently this creates chaos: uncertainties in Pluto's position in its orbit grow by a factor of e every 10–20 million years. This makes long-term simulations of the Solar System hard. (4/n)

        1 reply 6 retweets 144 likes
        Show this thread
      5. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        The planet Mercury is especially susceptible to Jupiter's influence! Why? Mercury's perihelion, the point where it gets closest to the Sun, precesses at a rate of about 1.5 degrees every 1000 years. Jupiter's perihelion precesses just a little slower. (5/n)

        3 replies 5 retweets 103 likes
        Show this thread
      6. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        In some simulations, Jupiter's gravitational tugs accumulate and pull Mercury off course 3-4 billion years from now. Astronomers estimate there's a 1-2% probability that it could collide with Venus, the Sun, or Earth - or even be ejected from the Solar System! (6/n)

        2 replies 13 retweets 143 likes
        Show this thread
      7. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        In 1989, Jacques Laskar showed that the Earth's orbit is chaotic. An error as small as 15 meters in measuring the position of the Earth today would make it completely impossible to predict where the Earth would be in its orbit 100 million years from now! (7/n)

        1 reply 22 retweets 158 likes
        Show this thread
      8. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        In 2008, Laskar and Gastineau simulated 2500 futures for the Solar System, changing the initial position of Mercury by about 1 meter. In 20 cases, Mercury went into a dangerous orbit! Often it collided with Venus or the Sun - but in one case it made Mars hit the Earth. (8/n)

        5 replies 37 retweets 207 likes
        Show this thread
      9. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        But here's the good news: the work of Laskar and Gastineau - and also another team - shows that nothing dramatic should happen to the planets' orbits for the next billion years. So we can worry about other things. (9/n)

        4 replies 18 retweets 181 likes
        Show this thread
      10. John Carlos Baez‏ @johncarlosbaez Jan 12
        • Report Tweet

        In the *really* long term, most of the stars in the Milky Way will be ejected. Through random encounters, individual stars will pick up enough speed to reach escape velocity. The whole Galaxy will slowly "boil away". It will dissipate in about 10^19 years. (10/n, n = 10)

        19 replies 22 retweets 265 likes
        Show this thread
      11. End of conversation
      1. New conversation
      2. Mohit Thatte‏ @mohitthatte Jan 12
        • Report Tweet
        Replying to @johncarlosbaez

        Does chaotic mean “we can’t predict how it will behave” or that it’s behaviorable is “not predictable”?

        3 replies 0 retweets 2 likes
      3. The Blue Wizard (next: Fur the 'More)‏ @TheBlueWizard9 Jan 12
        • Report Tweet
        Replying to @mohitthatte @johncarlosbaez

        See https://en.wikipedia.org/wiki/Chaos_theory …. Basically, it has the property that no matter how tiny the difference in the initial conditions for the system were, the systems will eventually show wildly divergent history of actions. BUT, identical conditions result in identical history of 1/2

        2 replies 0 retweets 8 likes
      4. 5 more replies

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