[acecharly (OP)]

If we imagine the universe starting from a singulrity, then as matter formed, how could it not expand in all directions perfectly from a perfect point unless there was some force to disturb it one way or another before hand. Id have thought it must expand out in all directions the same in a perfectly symetrical way but it obviously doesnt.

Cheers

Ace

[JP]

Because the universe isn't an explosion out from a point that's expanding into empty space.  The whole universe was part of the same singularity.  Because of this, every point in the universe today came from the same starting point, so why should any direction be different from any other?

[yor_on]

You will need to introduce some more dimensions to define a center I think It might be possible mathematically but I doubt it will make sense for us intuitively. Remember that balloon expanding? If only the outer skin is a two dimensional analogue to the four dimensional continuity we exist in, what would the rest of the balloon represent?

[acecharly (OP)]

Im not sure if ive explained my question properly as i found it hard to describe. If we use the baloon as an analogy then maybe the center is not everywhere maybe it is inside the balloon and everything has moved away from the center equally.

Getting back to my question though i dont see how matter could clump together for example as everything is equal at the singularity and must expand equally on all sides as there is no more gravity anywhere more than anywhere else any force must be in equilibrium the complexity we see today in the universe seems impossible to me why is there a galaxy in one part of space but not in another. If you burst a balloon full of water it does not spread out equally as there are outside forces at play such as gravity pulling down or depending wheres you burst the balloon pressure would realease more from that area but from this singularity there were no forces gravity would be above below to the sides if it existed. Maybe a ripple on a pond is another way to describe what im saying it moves outwards perfectly until it is disturbed by something else. At the singularity were told there was the singularity and nothing else. Does this make more sense?

[yor_on]

No space is assumed to be isotropic and homogeneous. It means that all physics experiment should behave the same anywhere you are, inside SpaceTime, now presuming equivalent setups for them. And the BB was the beginning of that, the inflation 'spreading and widening' all 'points' from each other, as if having a infinitesimally small cluster of ? 'energy/bosons/photons' that the inflation then started to introduce 'space' in between, so each point would see all other points move away from it, expanding the Space/Time. The reason matter is clumped together instead of ? gone/equalized is that we have 'gravity' that coupled to the matter 'clumped it together', resisting the 'inflation' and its later expansion. As I understands it that is.

So it doesn't matter which 'point' you measure all other 'points' from, as the inflation get up to 'speed' You will see the same phenomena in/at all directions, everything 'moving away' from you. Just pick a 'point' and look.

The idea with the balloon isn't that good really for describing it, one has to remember that it only is that outer 'skin' that represents those four dimensions we see. The inner side of the skin has no existing/visible analogue in SpaceTime. But it gives an idea of the 'mechanism'.

[Nizzle]

The idea with the balloon isn't that good really for describing it, one has to remember that it only is that outer 'skin' that represents those four dimensions we see. The inner side of the skin has no existing/visible analogue in SpaceTime. But it gives an idea of the 'mechanism'.

Maybe the 'skin' of the balloon only represents the 3 spatial dimensions, and an arrow, perpendicular to the skin and pointing outwards is the time dimension. The balloon is inflated from past to future, and the 'center of the balloon' is 'all the skin at time = 0', more commonly known as 'the singularity'

[imatfaal]

Ignoring the spreading out from a point - which has been dealt with above - the question as to why the universe is not homogeneous and isotropic on a small scale is still outstanding.  There are a few things to think of - quantum fluctuations (which are on the very smallest scale and happen randomly) that are magnified up by the expansion, and the acoustic pressure waves which tend to create volumes of space that are denser and others that are sparser.

Bear in mind that everything that happened to the universe prior to the era of last scattering (this is when/where the cosmic microwave background radiation was emitted) is not presently observable.  We can see the radiation given off when the universe was 379,000 years old, and at most points since then (we just need to point our telescope in the right direction).  But prior to 379kyr after BB the universe was opaque to light of all frequencies and thus we cannot observe anything earlier (until we learn to use neutrinos or gravitational waves).  Thus everything must be extrapolated from the CMBR and other currently observable radiation. 

[yor_on]

I think of it as 'emergences' myself gaining new properties through 'scales', 'temperatures' (presuming particles interacting) and what more?