[chris (OP)]

The Big Bang transformed energy into physical matter. TV shows usually portray the event - dubiously - as a huge colourful, noisy explosion.

So what would it have looked like to an external observer?

[Blame]

Well, presuming the big bang went off as advertised there was no outside. It was the whole universe that popped up.

[jerrygg38]

The Big Bang transformed energy into physical matter. TV shows usually portray the event - dubiously - as a huge colourful, noisy explosion.

So what would it have looked like to an external observer?

   Interesting question.As I see it everything that exists in our universe was formed at big bang.The explosion involved a huge amount of photonic energy which radiated outward. At the same time mass was forming.
  An independent observer within the expanding bubble and composed of our type of structure would see blinding light. If he was composed of a different structure and was outside the bubble he would see nothing at all.

[LarryLee Booth]

if you were outside the bubble you wouldn't be able to see anything until after the end of inflation when the first galaxy's started to form structures and slow the expansion from the inside out from ether inside or out of the bubble i don't think you would be able to see past the w-map image or not much past 

[JohnDuffield]

The Big Bang transformed energy into physical matter. TV shows usually portray the event - dubiously - as a huge colourful, noisy explosion.So what would it have looked like to an external observer?

Like the guys suggested, it's tricky to talk about an "external observer". The Big Bang was the rapid expansion of space, not some explosion of matter/radiation in space. So lets make you an observer in that space, protected by a bubble of artistic licence.



What do you see?

Nothing.

It sounds surprising, but the early universe had a huge energy density. It's likened to a black hole, and at the black hole event horizon, the energy density goes so high that gravitational time dilation goes infinite. So if you were at that location, in a bubble of artistic licence, it takes you forever to see anything. So you don't see anything. You see nothing. Note though that black holes do form, and they do get bigger as more matter falls in. They evolve, even though you're subject to infinite time dilation. The black hole is changing, but you can't see it changing.

In similar vein the early universe was changing, but you couldn't see it changing. Not until the energy-density dropped enough such that you were no longer subject to that infinite time dilation. Then you would have gradually become aware, like waking up from suspended animation. Perhaps initially everything was dark, and all of space was akin to some strange exotic form of energy. Perhaps outside your bubble of artistic licence space resembled the "void in the fabric of space and time" mentioned in the Wikipedia gravastar article. Maybe it was a fade from black rather than a fade to black. Or maybe there was a shattering crack as and blinding light like jerry was saying. I don't know. But at some time you'd find yourself in the "seething maelstrom" that was the early universe. I don't know when exactly, and I'm not confident that we can really say it was within a second of the Big Bang. But space somehow "rang like a bell" and was suddenly full of waves interacting with pair production and annihilation and QGP-melting going on. You'd be in a firestorm plasma of protons and electrons and photons and neutrinos and other particles. This would look like being in the middle of the Sun, all round your bubble of artistic licence. Only worse.

[jeffreyH]

So John at the same time as there only being a quark-gluon plasma you also envision protons whizzing around. Do you actually know what constitutes a proton? Also what other particles do you see in this 'firestorm'. I hope they are not made up of quarks otherwise your hypothesis is in serious trouble.