BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Is the Outer Solar System Chaotic? - Wayne Hayes (University of Ca
 lifornia)
DTSTART:20100525T120000Z
DTEND:20100525T130000Z
UID:TALK24366@talks.cam.ac.uk
CONTACT:Laurène Jouve
DESCRIPTION:The stability of our Solar System has been debated since Newto
 n devised\nthe laws of gravitation to explain planetary motion.  Newton hi
 mself\ndoubted the long-term stability of the Solar System\, and the quest
 ion\nhas remained unanswered despite centuries of intense study by\ngenera
 tions of illustrious names such as Laplace\, Langrange\, Gauss\, and\nPoin
 care.  Finally\, in the 1990s\, with the advent of computers fast\nenough 
 to accurately integrate the equations of motion of the planets\nfor billio
 ns of years\, the question has finally been settled: for the\nnext 5 billi
 on years\, and barring interlopers\, the shapes of the\nplanetary orbits w
 ill remain roughly as they are now.  This is called\n"practical stability"
 : none of the known planets will collide with each\nother\, fall into the 
 Sun\, or be ejected from the Solar System\, for the\nnext 5 billion years.
 \n\nAlthough the Solar System is now known to be practically stable\, it m
 ay\nstill be "chaotic".  This means that we might---or might not---be able
 \nto precisely predict positions of the planets within their orbits\, for\
 nthe next 5 billion years.  The precise positions of the planets can\neffe
 ct the tilt of each planet's axis\, and so can have a measurable\neffect o
 n the climate.  For the past 15 years\, there has been some\ndebate about 
 whether the Solar System exhibits chaos or not: when\nperforming accurate 
 integrations of the planetary motions\, some\nastronomers observe chaos\, 
 and some do not.  This is particularly\ndisturbing because it is known tha
 t inaccurate integration can inject\nchaos into a numerical solution that 
 would otherwise be stable.\n\nIn this talk I will demonstrate how I closed
  that 15-year debate on\nchaos in the solar system by performing the most 
 carefully justified\nhigh precision integrations of the orbits of the oute
 r planets that has\never been done.  The answer surprised even the astrono
 mical community\,\nand was published in _Nature Physics_.\n\nI will also s
 how lots of pretty (but as yet unpublished) pictures at\nthe end\, demonst
 rating the fractal nature of the boundary between chaos\nand regularity in
  the outer Solar System\, and the chaotic interplay\nbetween the inner and
  outer planets in our Solar System.\n
LOCATION:MR14\, DAMTP\, Pav. F
END:VEVENT
END:VCALENDAR