From: Paul Doherty (pauld@exploratorium.edu)
Date: Wed May 16 2001 - 16:07:01 PDT
Message-Id: <l03110733b728b7dd6095@[192.174.2.173]> Date: Wed, 16 May 2001 16:07:01 -0700 From: Paul Doherty <pauld@exploratorium.edu> Subject: Re: pinhole Re: Great Attractor
Hi Sidney
We are moving at a few hundred kilometers per second toward the great
attractor. Far short of the speed of light of 300,000 km/s.
Yes the motion is relatively linear and it is speeding up. However it will
not speed up to anything approaching the speed of light.
Objects in circular orbits travel at constant speed, gravity changes their
direction of motion.
Objects in elliptical orbits speed up and change direction as they fall
toward the focus with the gravitating object and slow down as they move
away.
I have a question from the excellent Astronomy Day last week. We
learned that gravitational force is pulling our group of galaxies towards a
"Great Attractor," a distant galactic supercluster. My question is
whether our speed towards this object is accelerating. Most of the other
trajectories I know about in space are orbital, with the shape of ellipses
-- the earth and comets around the sun, the sun around the Milky Way galaxy
center, the Milky Way Galaxy around the center of its cluster. I have
assumed that these motions proceed at a constant speed, with the additional
gravitational energy going into changing the orbital object's direction.
(Is this right? People say, "sun is rotating around the galaxy at
such-and-such a speed.) But if our galactic cluster is moving on a
straight line towards the Great Attractor, its speed should be constantly
increasing. Wouldn't it attain the speed of light i! n no time at all due
to the mathematics of geometrical increase, the constant tug of gravity
making it go faster and faster all the time? Are we moving at the speed of
light towards the Great Attractor? I would also like to know more about the
exciting new discoveries concerning the "sound waves" produced by the Big
Bang, and their responsibility for the distribution of matter in the
universe into great walls and empty bubbles. Why would matter collect
around the "noise" spots produced by the Big Bang? What a fascinating day
-- thanks to all concerned!
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Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld
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