Further Confirmation of the Big Bang

The Big Bang / BBC Science

The Big Bang / BBC Science

And it all started with a Big Bang…

Everyone knows our universe began with a Big Bang.  Actually, it is probably more accurate to say that approximately 13.8 billion years we know that what we can observe seemed to have underwent a significant phase transition, which directly led to the creation of all known matter and energy, and perhaps led to the existence of space and time itself.  But we don’t know that the Big Bang was the start of everything there is.  We don’t know whether there are other areas of our universe that existed pre-Big Bang.  And perhaps more importantly, we don’t know what caused the Big Bang itself.

However, I definitely don’t want to undersell how powerful a theory the Big Bang theory is.  The Big Bang theory is the central, guiding theory in all cosmology, and can explain nearly every aspect of the universe we observe.  That is quite an ambitious and successful theory by any measure.  And last month the Big Bang theory got a big boost by a team of international researchers that massively strengthened one of the four observational pillars of the Big Bang.

For everyone who doesn’t know, the four observational pillars of the Big Bang are:

  1. Expansion of the fabric of space
  2. Cosmic Background Radiation
  3. Abundance of light elements
  4. Galactic evolution and distribution

The observed expansion of spacetime itself is crucial to supporting the idea that our observed universe started with a Big Bang.  All galaxies are rushing apart from each other.  The further apart two galaxies are, the further apart they are rushing apart.  This expansion has been ongoing since the beginning of spacetime itself.  We can extrapolate expansion rates into the past, and with help from Einstein’s theory of general relativity, we can get an estimate on the conditions of the early universe.

The Cosmic Background Radiation (CBR) is equally important to understanding the Big Bang as the expansion of spacetime.  Discovered in the 1960s, the CBR is empirical confirmation that the universe was once in a primordial state with no galaxies or stars.  It is actually a snapshot of time approximately 380,000 years post-bang when the universe had just started to form atoms and photons were first able to roam freely.  This period in the universe’s development was predicted by the general theory of relativity, and thus is a fantastic example of the predictive power of the theory.

The fourth pillar (we’ll get to the third after!) is also important.  We now know that galaxies have evolved in a quite straightforward direction of time.  As the universe expanded gravity pulled slightly unevenly distributed matter into larger and larger clumps.  First gravity sculpted clouds of hydrogen.  Then young galaxies.  Then super clusters of galaxies.  Today the largest structures in the universe are galaxies connected like giant cosmic filaments.  Our universe as a giant web of matter (that is admittedly being ripped further and further apart).

Finally, the third pillar: the abundance of light elements.  For a while chemists wondered how we could possibly explain why 99% of the universe was composed of the lightest elements: hydrogen, helium, and lithium.  Stars are chemical factories, but the known process of thermonuclear fusion predicts that there should be a higher percentage of heavier elements than observed.  The only way we can explain the observed abundance of light elements is if the universe was once as hot and dense as a star for a short period of time.  If this was the case we should suspect that the universe in this state would have only been able to produce the lightest elements, which would explain why they are so abundant.

Wait… that is what the Big Bang theory predicts!  Perfect!  This phenomenon is called “Big Bang nucleosynthesis“.  But there is a problem.  Scientists have shown that the Big Bang theory roughly accounts for the amount of hydrogen and helium observed.  Over the past few decades astronomers have observed that there are two times the amount of two Lithium isotopes (Li-6 and Li-7) than Big Bang nucleosynthesis could account for.  This is a major problem that cosmologists have been working to resolve now for over twenty years.  Some scientists suspected that there could be pre-galactic fusion cores that we don’t have the technology to observe yet.  Some thought there was a big enough discrepancy in observations to that justify re-working the Big Bang theory itself.

However, last month the aforementioned Big Bang pillar-reinforcing study demonstrated that the problem was technological.  The authors claim that the observed over-abundance of lithium was due to poor observational quality in the past.  In their study, utilizing the powerful W.M. Keck Observatory’s 10-meter telescope, they completely reconciled the Big Bang theory with the observed abundance of lithium.

As a result, the pillars are stronger than ever.  Our universe, at least what we can observe of it, started with Big Bang.  Future studies related to reinforcing the pillar of the Big Bang will now be focused on observing the first stars and galaxies in our universe’s history.  In order to do that, astronomers will have to wait for the James Webb Space Telescope, which is the planned successor of Hubble and is scheduled to launch in 2018.

What do you think of this scientific development?  Let Cadell know on Twitter!

About Cadell Last
Hello. I'm probably drinking coffee and reading.

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