Deakin Communicating Science 2016

EES 200/101

Me, Myself and the Universe

And so it begins.

Over the coming month or so I will aim to write a short series of blog posts covering three of my favourite aspects of astrophysics.

It seems appropriate, then, that my first blog covers the origin of the universe!
How did it all begin?

There have been many theories as to how the universe began, assuming that it did of course, ranging from the commonly known big bang model to the more comical sneeze of the Great Green Arkleseizure (It is at this point that I hope there are some fans of Hitchhikers Guide to the Galaxy here).
Some theories, we now know, have more merit than others.

The idea that the universe had a beginning has caused controversy and division over many years, ranging from scientists, philosophers and all manners of religious followings.
People seemed to like the idea of a constant, infinite universe.
Immanuel Kant had problems with both an infinite and finite universe. His opposition lying on the foundations of his thesis and antithesis.
Why would the universe wait an infinite amount of time to begin (thesis) or, alternatively, if the universe always existed, why did it take an infinite amount of time to reach this point (antithesis) [1][2]

The scientific notion (as opposed to philosophical) that the universe had a beginning stemmed greatly from the discoveries of Edwin Hubble.
Hubble discovered that the universe was expanding! [3]
As a thought experiment, if you look at this model in reverse (backwards in time) the universe would be shrinking, and it would eventually get to the time when all the matter occupies a single point.
This is known as a singularity.[1]
This lead to the big bang model, and eventually to the cessation of the steady-state theory.

There are two key pieces of information supporting the big bang model that I wish to share with you.

The first is quite probably the most confusing graph I have ever seen in my life.
This figure shows the relative expected amount of light elements deuterium (Hydrogen with a neutron attached), helium, helium-3 (helium with only one neutron) and lithium with respect to hydrogen all based on our knowledge of the big bang.

mohr_concordance.jpg

Figure 1: Predicted abundance relative to hydrogen from big bang model. [4]

The green, red and purple bands all show the expected abundance relative to hydrogen at certain baryon densities.
The unshaded boxes show accepted ranges of the estimated abundance present as primordial elements (elements present shortly after the big bang).
The blue band shows the region in which all the predictions coincide.
The mere fact that we were able to find a region at which these predictions match for the primordial elements is a great support for the big bang model. [5]

The next is another interesting figure, but this one is a little easier to understand!
The following images show the CMB (cosmic microwave background) radiation of our universe. That is, the radiation left over from the big bang.

cmbr.jpg

Figure 2: The measured CMB radiation (top)  compared to predictions for closed, flat and open universes respectively. [6]

Using the observed data and the predictions scientists determined that our universe is flat.
This coincides with the inflationary model of the expansion of the universe! [6]

This is most easily seen when considering a balloon.
As the balloon inflates/expands it becomes flatter.
I know you may be thinking ‘of course the balloon is still curved’, but consider the Earth, we perceive it as flat despite knowing it is roughly spherical.
We observe the universe as we are, as flat.

While we now have a good idea of how the universe was created once the big bang had occurred, we still aren’t able to understand the moments before and during the start of the big bang.
This is where the controversy and difficulty comes in for modern days.
From a scientific point we are unable to combine the two necessary fields of physics (relativity and quantum theory) to understand the whole big bang.
Research into discovering this has lead to scares of creating black holes that would destroy us all (see CERN hadron collider), although this notion is largely a media scare.
Lastly, should we be dabbling in the origin, or as some would say, creation of the universe, as it is not our place to understand it.

If you are interested in learning more about the origin of our universe I very highly recommend reading Laurence Krauss’ ‘A universe from nothing’.
Although some of the content is a little tougher to get your head around, it truly is a rewarding read.

References:
1 – Hawking. S, ‘The Origin of the Universe’, copyright date unknown, cited 12/04/2016, <http://www.hawking.org.uk/the-origin-of-the-universe.html&gt;

2- Grier. M, ‘Kant’s Critique of Metaphysics’, published 29/02/2004, revised 10/04/2012, copyright 2012, cited 12/04/2016 <http://plato.stanford.edu/entries/kant-metaphysics/&gt;

3- Bagla. J, ‘Hubble, Hubble’s Law and the Expanding Universe’, Resonance: Journal of Science Education, cited 14/04/2016, published 01/03/2009, pp. 216-225, <http://eds.b.ebscohost.com.ezproxy-f.deakin.edu.au/eds/pdfviewer/pdfviewer?sid=3d48e435-6275-44ac-a6c0-6b0debd6eb05%40sessionmgr102&vid=5&hid=121&gt;

4- ‘The Bug bang, Nucleosynthesis, and the Formation of Structure’, cited: 14/04/2016, <http://www.astro.princeton.edu/~burrows/classes/250/bb_nucleosynthesis.html&gt;

5- Krauss. L, ‘a universe form nothing’, Great Britain: Simon and Schuster 2012

6- BBC, Pictures of the early universe, published 28/04/2000, cited: 14/04/2016, <http://news.bbc.co.uk/2/hi/science/nature/729750.stm&gt;

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This entry was posted on April 18, 2016 by in Uncategorized.

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