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This problem has been growing for a number of years.  It is officially called the Impossible Galaxy Problem.  The standard model of cosmology makes firm predictions about the timeline of our Universe.  You are probably familiar with this from school but let’s recap some of this information to help understand the nature of the problem.

The Cosmological Timeline

The Universe started with what we term the Big Bang.  Time and space came into existence (technically there was no bang), they formed from a gravitational singularity but our Physics is not capable of describing it.  The closest we can come to it, is what is called the Planck Era, at 10-43 seconds after the Big Bang.  It is believed that all the forces had the same strength or were possible unified.  The universe is only 1 Planck Length long (10-35 m).  Then came the Grand Unification Epoch where gravity separated from the other forces and the first particles started to form (10–43 seconds to 10–36 seconds). Then comes the Inflationary Epoch, the Universe undergoes an extremely rapid expansion known as cosmic inflation and expands from its very small size to about 1cm (from 10–36 seconds to 10–32 seconds).  We then move through several other epochs where more fundamental particles form until we finally get to the Photon Epoch where the universe is filled with hot plasma.  Photons dominate the energy of the universe and interact with charged protons, electrons and nuclei meaning the universe is opaque.  This period lasted from 3 minutes until 240,000 years.  We then enter the Recombination epoch.  The temperature has now fallen to around 3000 Kelvin.  The electrons become bound to the protons forming the first hydrogen atoms and helium atoms.  Photons can now finally travel freely and the Universe turns transparent.  We then enter the Dark Age lasting from 300,000 years to 150 million years.  No stars have formed so there are no new photons being created.  The first stars form at around 300 million to 400 million years.  These are what are termed Population III stars and are metal free, they are supposed to be large and burn out quickly.  Around 800 million years after the Big Bang the first small galaxies are formed.

In order to determine the age of the celestial bodies that we observe we look at their Red-shift.  Cosmology relies on a 1:1 relationship between the redshift of an object and its age.  In the article on Quasars, I have already pointed out there is mounting evidence that certain object might exhibit an intrinsic red-shift which is not due to recessional velocity and therefore would make it appear that it is much older than it actually is.

The Impossible Galaxy Problem

As our space-based telescopes have vastly improved over the years we have been able to detect fainter and fainter signals from what we believe is the earliest time of the Universe.  The problem is that some of these objects simply should not exist.  They have detected examples of supermassive galaxies which have a red-shift of 10 which corresponds to an age of 600 million years after the big bang.  As we have seen above this is a mere 200-300 million years after the first stars formed.  This is physically impossible to get these supermassive galaxies.  This is why it is called the Impossible Galaxy Problem.  This problem is now not just confined to supermassive galaxies but they have also detected supermassive black holes which date to 800 million years after the Big Bang.  These are 1 billion solar mass objects which have formed in 500 million years!

So how do they solve this problem?  You either have to change the physics or you have to change the cosmology.  So far no-one is brave enough to tackle the fact that maybe the Physics is wrong.  Instead, some propose changing the period of inflation to extend it until it matches up with our observations.  You can find some of these proposed ideas in the Further reading section.

More problems…

A montage shows where the arc lies relative to the galaxy cluster.
NASA, ESA, A. Gonzalez (Univ. of Florida), A. Stanford (UC Davis and Lawrence Livermore National Laboratory), and M. Brodwin (Univ. of Missouri and Harvard-Smithsonian Center for Astrophysics)

Anthony Gonzales, while reviewing some Hubble images stumbles across a striking image of a distant, large, spiral type galaxy being warped into an arc shape by gravitational lensing, nestled amongst a massive cluster of galaxies.  It is estimated that this galaxy formed around 1 billion years after the Big Bang.  The problem with the images comes from the alignment of the background galaxy and the foreground galaxy cluster.  In his paper, Gonzalez finds the odds of this alignment happening almost impossible and he stated that “This arc simply should not exist”.  The problem here is that the size of the galaxy cluster in the foreground and the brightness of the arc cannot be predicted by current models.

Problems closer to home

Rocket, Meteor, and Milky Way over Thailand Image Credit & Copyright: Matipon Tangmatitham

It is believed that our Milky Way galaxy formed through a merger with smaller galaxies over a vast timescale.  The oldest stars should be found in the centre around the galactic ore.  It is believed that the arms are a newer structure and should contain only newer younger stars.  New observations have found a very, very old star living in the spiral arm of the galaxy.  This is a Population III star, a metal free-star, which according to our timeline above was one of the first stars to be born.  These early stars were giant stars who burned bright and lived short lives, yet here we find one (bright blue) happily living in the Milky Way arm which formed much later the galactic core!  Again this points to the fact that something does not add up with our current understanding of how the Universe formed.  In future articles, I would like to turn my attention to stars and examine alternative models for not only star formation but their evolution which may help to explain how such a star can exist at all.  Follow the evidence, be brave, be curious, the truth is waiting for us. Until next time…

Further Reading

An Ultra Metal-poor Star Near the Hydrogen-burning Limit



A Cosmological Solution to the Impossibly Early Galaxy Problem