Firstly, I apologise if my thinking is completely incorrect - I am by no means a physicist (yet!), I have included layman illustrations to hopefully assist in explaining my thinking.

I am imagining the big bang to be, for lack of a better word, an explosion, thus the universe to be progressively expanding:

enter image description here

Therefore, to me it seems logical to suggest that there is an edge.

If this is the case, then is it reasonable to suggest that explosion + edge = 'bright edge'? Where light projects in all directions at the edge, not just outwards into the 'nothingness'.

enter image description here

So, this brings me to my question: why, when someone looks deeply enough 'at the edge' do they see an absence of light?

Again, apologies if I'm jumping to irrational conclusions & am way off.


marked as duplicate by Brandon Enright, Kyle Kanos, John Rennie, Emilio Pisanty, user10851 Apr 7 '14 at 20:52

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


You are thinking that the big bang happened in a particular point in space and then expanded outwards from that point. This is not true. The big bang happened at all points in space. This is because space itself expanded in the actual bang. Therefore each point in space has its own "horizon" of 13.7 billion light years across.

This edge is due to light simply not having enough time to reach that point, therefore nothing can be observed beyond that point. It is not a literal edge.

  • $\begingroup$ Thanks for the answer mate. Im struggling to understand how the big bang happened 'at all points in space' - do you have some further reading? Many thanks :) $\endgroup$ – HarryChil Mar 30 '14 at 17:30
  • $\begingroup$ My pleasure! We're all here to ask and learn $\endgroup$ – Constandinos Damalas Mar 30 '14 at 17:32
  • 2
    $\begingroup$ Well stop thinking of the big bang as an explosion happening from some point. Think of it like this: If the distances between each point in space doubles, where is the centre? Everywhere and nowhere! Does this make sense? $\endgroup$ – Constandinos Damalas Mar 30 '14 at 17:39
  • 1
    $\begingroup$ "Wow. Yeah I get it now. Wow, thanks man." Moments and reactions like these are why people teach. =] $\endgroup$ – ahnbizcad Jan 19 '15 at 10:07

One cannot simply observe edge of universe without taking in consideration of the big bang being a silent inflation rather than a large explosive inflation. As when universe was created the temperature was too hot for matter to exist thus the photons being pure energy rather than a bright explosion. Next, if the big bang happened in presence of matter existing the photons should NOT be in our human naked eye spectrum and rather in gamma rays.

Next, the light (if produced) will take the current age of the universe to reach our planet that being if all points in our universe are somehow the center of the universe. Else the light should take current age of universe minus the relative position of earth to the edge of universe.

That being said, by the time we get the light the universe would have been expanded so we can never really see the "real-time" universe edge without actually travelling there which is out-right impossible with our current technology and our future technology for a while.


Not the answer you're looking for? Browse other questions tagged or ask your own question.