April 2, 2009 | David F. Coppedge

Early Large Galaxies Stun Cosmologists

Cosmology has a kind of Cambrian Explosion of its own to grapple with.  Contrary to expectations, some of the earliest galaxies appear as large as current ones, if not larger.  Astronomers, using the Subaru telescope in Hawaii, examined five galaxy clusters with ages estimated at 5 billion years after the Big Bang.  Statements in a report on this study in Nature News make it sound revolutionary:

  • The findings could overturn existing models for the formation and evolution of galaxies that predict their slow and steady growth through mergers.
  • They calculated the mass of the biggest galaxy in each of the clusters and found, to their surprise, that the ancient galaxies were roughly as big as the biggest galaxies in equivalent clusters in today’s Universe.
  • The ancient galaxies should have been much smaller, at only a fifth of today’s mass, based on galaxy-formation models that predict slow, protracted growth.
  • “That was the reason for the surprise – that it disagrees so radically with what the predictions told us we should be seeing,” says Chris Collins of Liverpool John Moores University in Birkenhead, UK.
  • “We have a whole different story now about how galaxies form,” says Avishai Dekel of the Hebrew University in Israel and first author of the earlier paper.
  • For years, astronomers have relied on a hierarchical model of galaxy formation…. the models predicted that, to reach the massive galaxy sizes seen today, galaxies would have to steal their stars through mergers – a slow process – rather than growing their own.
  • It’s not yet certain how much of a readjustment the hierarchical model will need if the observations hold up…. But Collins says the underlying models of dark-matter mergers could have problems.  “I think the problem could be more general than just needing a tweaking.

Continuing the Cambrian explosion parallel, both the hierarchical model and newer, more radical model have to come up with a lot of growth and structure in a shorter amount of time.  The simple hierarchical model, which expected stars would grow into galaxies and then into clusters, ran into problems early on, when it was realized that when cool hydrogen flows toward a nascent galactic center, it heats up.  The heat quenches or stops further star formation, because “Shock waves are produced that expand outwards to agitate and heat up new gas on the periphery, preventing it from collapsing and falling in to form new stars.
    That was the reason astronomers had for years used mergers to explain the growth of galaxies.  If large galaxies already existed in the early universe, though, mergers become implausible.  What is the alternative?  One group suggests “veins of cold gas, clinging to filaments of dark matter” that can “pierce the hot gas shell of a growing galaxy and fuel its continued growth” and lead to early galaxies growing “rapaciously”.  It sounds like an ad hoc solution.  It was proposed to get around the age problem.  Is there any evidence?  No one has seen dark matter, or knows what it is.  The story ended with a hunt to explain “glowing blobs of hydrogen gas in distant, ancient corners of the Universe” that might correspond with the proposed filaments.  All parties agree that “more work needs to be done.”

We can see here the kind of mental gymnastics Darwinists would perform if someone found a Precambrian rabbit.  The surprise level seems almost comparable.  It never changes their core beliefs; it just changes the implausibility of the natural miracles they are willing to invoke to maintain their world view.  For background, read an article in this month’s ICR magazine.

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Categories: Astronomy, Cosmology, Physics

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