University Lowbrow Astronomers

From Little Bitties To Big Bunchies?

by Lorna Simmons
Printed in Reflections: December, 2001.

You amateur astronomers have it easy.  All you do is point your telescopes, etc., and look at the marvelous Michigan sky whenever it is not raining or being obscured by clouds and light pollution.  The galaxies and other peculiar objects are out there waiting patiently for your undivided attention.  Sure....  Piece of cake....

Do you ever wonder how the galaxies, which everybody loves to view, came to emerge from their earliest seeds in the early universe finally to dazzle our eyes as the gorgeous monsters of more recent times?

The elliptical galaxies have certain similarities, which are easier to study.  The stars in the ellipticals tend to whiz around in every direction with great abandon.  This whizzing around seems to have gotten rid of a lot of stuff between the stars because of the constant collisions, which would occur in elliptical galaxies from the all-over-the-place-every-which-way movement of the individual stars.  Of course, at great distances, you cannot see the frantic movement but must be content with merely observing the faintly fuzzy floating phantoms.

Elliptical galaxies are distinctly redder than the spiral galaxies and tend to resemble jewels in the sky.  Sadly, after awhile one elliptical galactic jewel appears similar to all of the other elliptical galactic jewels, and we yearn for the variety which we see in the stately grand spiral galaxies, in the magnificent barred spirals of even more recent epochs, and in the irregular galaxies formed by galactic mergers, etc.  Spirals are great, gorgeous, stately whirlpools of stars.  If your telescope has enough aperture, you can see the resulting great beauty of their majestic journey, although you cannot actually see their true movement because of their great distance.

Did you ever wonder how spiral and elliptical galaxies came to be formed in the first place in the early universe?  Did the stars in the galaxies begin as part of gigantic conglomerations, mixing and churning away, or did the galaxies ever so slowly develop from tiny bits of matter getting together and adding themselves to other tiny bits of matter (a/k/a accreting), eventually becoming the big monsters of recent cosmological epochs?  It is a puzzle that astrophysicists and cosmologists have yet to solve.  They say they’re working on it.  Sure....  We know....  Yeah....

Well, if you really want to know all of the answers, many present-day cosmologists (but certainly not all) suggest that there are two major possibilities.  One is a monolithic collapse scenario with all of the galaxies, ellipticals, spirals, and irregulars forming from the remnant matter produced by the Big Bang (which, by the way, was neither big nor a bang).  In other words, galaxies envisioned this way developed “from the top down”.  Everything simply slowly separated into smaller bunches of stars, eventually to form the familiar galaxies.  Did already-present elliptical galaxies become elliptical galaxies and already-present spiral galaxies become spiral galaxies, with never the twain mixing?  Would this be the kind of pattern continuing to the present day?  Good question....

On the other hand, perhaps everything occurred much differently.  Could the galaxies have been formed “from the bottom-up”?  Perhaps there originally was a slow gravitational collapse merging together little wisps and bits and pieces of material left over from the so-called Big Bang (named, derisively, by the late Fred Hoyle) to end up with larger and larger conglomerations of these little wisps and bits and pieces of material, eventually forming galaxies.  This process could continue on to make huge accumulations of stars and star-forming matter.  Again, perhaps....

Then, of course, add to both of these scenarios the omnipresent “dark matter” which is part of the great majority of the galaxies, which “dark matter” is only observed as a result of its gravitational effect on the easily-observed matter.  Additionally, there is the dark energy, unseen, except by its effects, which is now thought to be accelerating the expansion of our universe, simultaneously preventing the formerly-expected gravitational collapse between galactic groups.  The Big Crunch seems to have become only a cosmological theoretical memory nowadays.  Accelerating universes do not crunch.

Therefore, there seem to be two main ideas remaining at present as to the evolution of galactic groups:  (1) In the monolithic collapse scenario, galaxies of different morphological types (spirals and ellipticals) are born intrinsically different and continue that way unchanged as to their morphological type, to the present cosmological era.  (2) In the hierarchical merging scenario, galaxies end up as spirals or ellipticals depending on the details of their merger history.  They can change from one to the other, given the changing conditions.

Of course, everybody can wonder about all of the stuff which cannot be seen but which can only be imagined or found indirectly.  Making a living as a cosmologist takes a lot of imagination -- a whole big enormous lot of imagination...

Regardless of how everything got to where everything got, the simplest solution is to take your telescopes out in the night sky and enjoy!  Forget everything else and let the cosmologists worry about the meaning of it all.

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Copyright © 2013, the University Lowbrow Astronomers. (The University Lowbrow Astronomers are an amateur astronomy club based in Ann Arbor, Michigan).
This page originally appeared in Reflections of the University Lowbrow Astronomers (the club newsletter).
This page revised Sunday, March 9, 2014 4:30 PM.
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