REM@MC.LCS.MIT.EDU (Robert Elton Maas) (02/21/86)
(If the number of the Fixt Stars were more than finite, the whole superficies of their apparent light would be infinite) M> Date: Fri, 14 Feb 86 09:53:56 PST M> From: mcgeer%ji@ucbvax.berkeley.edu (Rick McGeer) M> Of course, the solution to the above paradox is that the universe M> expands, and hence the light from the furthest galaxies is redshifted, M> asymptotically to invisibility, and hence the total illumination of M> the sky is finite. Not quite correct, "A" (not "the") solution. Here's another, not needing redshift, nor even expansion although needing finite time: It's been a finite time since the Universe started, thus stars have burnt for only a finite time. Looking back in time, we see the complete life history up to the present for nearby stars, but only the early parts for stars further away because more recent life history hasn't had time to be transmitted to us at the speed of light. What we observe is a cone of space-time extending back to the origin of the Universe, a cone of finite space-time volume thus having only a finite amount of star*years of light-emitting, thus having only a finite total amount of light we can see. Therefore, even ignoring inverse-square dimming and redshift dimming, we have a finite total amount of light in the night sky. The inverse-square and redshift merely decrease an already-finite amount of light by orders of magnitude.
mcgeer%ji@UCBVAX.BERKELEY.EDU (Rick McGeer) (02/21/86)
(1) You're assuming finite volume to the Universe, as well as finite time (not a bad assumption); (2) The fact that time has a beginning is a relatively recent discovery (Hawking and Penrose, 1965), and is dependent upon the observed expansion of the Universe. Hence the universe can only be said to have a beginning in time if it expands. -- Rick.
holloway@drivax.UUCP (Bruce Holloway) (02/26/86)
In article <8602210943.AA05597@s1-b.arpa> REM%IMSSS@SU-SCORE.ARPA writes: >(If the number of the Fixt Stars were more than > finite, the whole superficies of their apparent light would be infinite) > >M> Date: Fri, 14 Feb 86 09:53:56 PST >M> From: mcgeer%ji@ucbvax.berkeley.edu (Rick McGeer) >M> Of course, the solution to the above paradox is that the universe >M> expands, and hence the light from the furthest galaxies is redshifted, >M> asymptotically to invisibility, and hence the total illumination of >M> the sky is finite. > >Not quite correct, "A" (not "the") solution. > >Here's another, not needing redshift, nor even expansion although >needing finite time: It's been a finite time since the Universe >started, thus stars have burnt for only a finite time. Looking back in >time, we see the complete life history up to the present for nearby >stars, but only the early parts for stars further away because more >recent life history hasn't had time to be transmitted to us at the >speed of light. What we observe is a cone of space-time extending back >to the origin of the Universe, a cone of finite space-time volume thus >having only a finite amount of star*years of light-emitting, thus >having only a finite total amount of light we can see. Therefore, even >ignoring inverse-square dimming and redshift dimming, we have a finite >total amount of light in the night sky. The inverse-square and >redshift merely decrease an already-finite amount of light by orders >of magnitude. Another solution (maybe): All stellar objects tend to "clump" into solar systems, galaxies, clusters, ad infinitum. So instead of spreading evenly throughout the sky, we just see light from these collections, the scope of said clumps depending on how far away the object(s) is/are. -- +----------------------------------------------------------------------------+ |Whatever I write are not the opinions or policies of Digital Research, Inc.,| |and probably won't be in the foreseeable future. | +----------------------------------------------------------------------------+ Bruce Holloway ....!ucbvax!hplabs!amdahl!drivax!holloway (I'm not THAT Bruce Holloway, I'm the other one.)
KFL@MC.LCS.MIT.EDU ("Keith F. Lynch") (03/07/86)
From: "Josh Knight" <JOSH%YKTVMH.BITNET@wiscvm.wisc.edu>
I don't think clumping, no matter what its statistical characteristics
can avoid the paradox.
Not true. An infinite hierarchy of clumping can avoid it, even in
an infinite, infinitely ancient, non-expanding universe. We know that
stars clump in galaxies, galaxies in clusters, and clusters in
superclusters. If we assume that superclusters, in turn, clump into
hyperclusters, ad that hyperclusters are not evenly distributed
either, but clump into untraclusters,... and so on and so forth
forever, we can avoid Olber's paradox. The paradox requires that
there be an average density of the universe. But in the inifinite
hierarchy model there is no average density. The larger a sphere you
describe about the Sun, the lower the density of material within it.
(Which is not to say we have any prefered position, the same would be
true from any other star in any other galaxy anywhere).
This inifinite hierarchy model was quite popular at one time. It is
a shame that it is out of fashion these days, as it is really quite
attractive.
"In an infinite universe I am bound to recur" -- Nietzche
...Keith