It was announced this week that after a 12 year long research project a team of scientists have gathered evidence showing the birth of the very first stars in our Universe.
This occurrence happened a ‘mere’ 180 million years AFTER the Big Bang – the event Cosmologists believe was the birth of our known Universe. Before that there was nothing but a relatively dense but expanding scattering of sub-atomic particles of extremely high energies and atoms of mostly Hydrogen. For the first 380,000 or so years the only things in existence were the most elementary particles (primarily photons) that would one day ‘cool’ and combine into matter, and the basic forces of physics.
Photons are the elementary ‘particles’ (they can exhibit both particle and waveform-like behaviours) of electromagnetic energy fields. One example of which is visible light – without photons none of us would be able to see anything!
It is thought that these particles first started to come into being about 10 SECONDS after the Big Bang. So while light itself existed shortly after the Big Bang, it took another 180 million years to pass before there was anything other than a haze of highly excited (high energy) hydrogen atoms and basic particles to actually see. The first stars then started to emit the first light generated from anything like matter as we know it today and from this all stars and galaxies were to follow, including (much, much later) our Sun.
The challenge of discovering this information was immense for 2 main reasons:
Firstly, the light has had to travel for some 13 billion years before it could reach us, travelling at the speed of light (300,000 km per second), meaning it is unimaginably far away* and therefore weak, especially when compared to all the ‘nearby’ light being received from the same area of sky the scientists were looking at (most light coming from within our own galaxy, the Milky Way). It would be like trying to see a candle from the far side of a well-lit city – in the daytime!
Secondly, the signal is so weak that even a mobile phone would introduce enough energy, if nearby the receiver, to disrupt the signal being received and affect the data and results. The receiver had to be located somewhere where any radio signal was not, under national law, being generated within 260 kilometers!
Turns out such a place exists, with a radio telescope observatory handy, in the Murchison region of my home state of Western Australia! Hence my interest. 🙂
This then got me thinking, yet again, on the topic of where our ‘place’ is in the Universe.
We know with a fair degree of accuracy whereabouts our Sun is in the Milky Way galaxy and roughly the direction to look at if we want to look for the very centre of the Milky Way (It’s in the constellation Sagittarius if you are interested!) but as for our ‘place’ in the Universe – we have absolutely no clue! And that really bugs me.
The problem is this: if everything started from a single point called the Big Bang and then exploded ‘outwards’ and later galaxies and solar systems began to form while expanding from that explosion we should be able to look around us and have some idea which way ‘stuff’ is flying around and be able to figure out what direction we came from originally – right?
Wrong! It does not matter where you look, in EVERY direction you can see evidence of the Big Bang shortly after it took place; forwards, backwards; left, right; up and down, as far as our radio telescopes can see (and they all see ‘backwards’ in time while looking out into space!). As far as we can tell we are smack in the middle of the never-ending explosion that happened over 13 billion years ago and are flying apart from all other parts. (Or at least our galaxy is).
The furthest visible galaxies – no matter where in the sky you look – are all over 13 billion light years away, meaning we are in the centre of the known Universe. It’s just that we don’t know where the real boundaries actually are or how close we are to any particular theoretical ‘edge’, and therefore can’t tell where the centre of the Universe is or our place in relation to it. It should be where the Big Bang’s ‘centre’ was.
* I did the math for you:
Light travels 9,467,280,000,000km/year (5,882,344,169,400 mi/y) so in 13 billion years it travels 13,000,000,000 x 9,467,280,000,000km = 123,067,298,834,400,000,000,000km!
That’s 123 thousand, billion, billion km or about 77 thousand, billion, billion miles!