Jack Wisdom

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Jack Leach Wisdom (born January 28, 1953 in Lubbock , Texas ) is an American physicist, known for celestial mechanical investigations that provided evidence of chaotic behavior in the solar system.

Wisdom graduated from Rice University with a bachelor's degree in physics in 1976 and a PhD from Caltech in 1981 . He is Professor of Planetary Science at MIT.

research

Wisdom is known for various results that show chaotic behavior in celestial mechanical problems of our solar system. For example, he found signs with Gerald Jay Sussman that Pluto's orbit is chaotic and very complicated compared to the orbits of the other outer planets on large time scales ( 845 million years were simulated on the Digital Orrery in 1988 ). After Jacques Laskar carried out a long-term simulation of the solar system (excluding Pluto) for about 100 million years in 1989, which showed signs of chaotic behavior, Sussman and Wisdom repeated and confirmed this on the Supercomputer Toolkit, a special computer for such simulations. The time scale for the development of chaotic behavior (according to the Lyapunov exponent ) is 4 to 5 million years.

One of the most striking examples of chaotic movement in the solar system is the orientation of the axis of rotation and the rate of rotation of the outer Saturn moon Hyperion , which Wisdom also studied. It is caused by a strongly irregular shape and the weak tidal forces of Saturn and is also particularly evident because of the great eccentricity of the orbit. According to Wisdom, chaotic phases occur in every irregularly shaped moon, shortly before its rotation synchronizes with that of the planet (resonance case). With Touma he also showed that the inclination of the axis of rotation of Mars in relation to the plane of the orbit is exposed to strong chaotic fluctuations, with effects on the Martian climate.

Wisdom also explained various gaps in the asteroid belt, like the Kirkwood Gap . They result roughly from a resonance with the orbital period of Jupiter (in the case of the Kirkwood gap in the ratio 3: 1), but this is not sufficient for an exact explanation, since with some resonance orbits no gap occurs. This required simulations of the orbits over long periods of time (millions of years), only then did peaks in the eccentricity of the orbit appear, which explained the kicking out and thus the creation of the gap.

To this end, he developed new numerical methods on the one hand (such as a symplectic mapping of the gravitational N-body problem with Matthew Holman) and, on the other hand, special computer hardware, such as the Digital Orrery in the 1980s with Sussman. The use of different procedures also allowed a mutual check of the invoices.

Wisdom also examined the earth-moon system and the development of the moon's rotation parameters, the interaction of the earth's core and mantle, and the volcanism on Saturn's moon Enceladus , driven by tidal effects that “kneaded” the moon . He was also engaged in the discovery of extrasolar planets (such as 55 Cancri f ).

In 2003, Wisdom proposed a mechanism of locomotion in the general relativistic space-time based solely on changes in the shape of the body; he called this swimming in space-time .

With Sussman and Mayer, he wrote an algorithm-oriented textbook on classical mechanics.

Awards and memberships

In 1986 he received the Harold C. Urey Prize , in 1987 the Helen B. Warner Prize and in 2002 the Dirk Brouwer Award from the American Astronomical Society (AAS). From 1988 to 1994 he was Presidential Young Investigator for the National Science Foundation. In 1994 he received a MacArthur Fellowship . He has been a member of the American Academy of Arts and Sciences since 1992 and of the National Academy of Sciences since 2008 .

Fonts

  • with Gerald Jay Sussman , Meinhard E. Mayer: Structure and Interpretation of Classical Mechanics, MIT Press 2001
  • Chaotic behavior in the solar system, Proceedings Royal Society A, Vol. 413, 1987, p. 109, online here PDF file

Web links

Individual evidence

  1. ↑ Sussman, Wisdom, Science Vol. 241, 1988, p. 433.
  2. ↑ Nature, Vol. 338, 1989, p. 237.
  3. ^ Wisdom, Sussman: Chaotic evolution of the solar system , Science Vol. 257, 1992, pp. 56-62.
  4. ↑ Wisdom, Touma, Science, Vol. 259, 1993, p. 1294. 4 million years ago the inclination was 45 degrees after that, much larger than the approximately 25 degrees today.
  5. ↑ in his dissertation. Published as: The origin of Kirkwood gaps , Astron. Journal, Vol. 87, 1982, p. 577.
  6. ^ Wisdom, Matthew Holman: Symplectic maps for the n body problem , Astronomical Journal, Vol. 102, 1991, p. 1528. Expanded by Touma and Wisdom to include rotational dynamics , Lie Poisson Integrators for rigid body dynamics in the solar system , Astron. J. Vol. 107, 1994, p. 1189.
  7. ^ Wisdom: Swimming in spacetime: motion by cyclic changes in body shape , Science, Vol. 299, 2003, pp. 1865–1869.
personal data
SURNAME Wisdom, Jack
ALTERNATIVE NAMES Wisdom, Jack Leach (full name)
BRIEF DESCRIPTION American physicist
DATE OF BIRTH January 28, 1953
PLACE OF BIRTH Lubbock, Texas