So what can we piece together from all of this stuff. There is a somewhat uniform temperature across the entire universe (the CMBR), and as far as distant stars are concerned they are moving away rather rapidly (redshift). This leads us to believe that at some point in time everything was much closer together at a much higher temperature. How close? So close that the entire universe would exist as a "singularity" (a single point in space). How much of a higher temperature? So hot that even electrons could not stay attached to atoms, even hotter still that the parts that make up a neutron or a proton, known as quarks, could not stay together, and everything sort of floated around in a "soup". You can see an example of inflation below.
Let's now discuss some of the problems with this theory of how everything began. Probably the most visible and least solvable problem is the existence of "dark matter" and "dark energy" now they didnt give this stuff these names because they are evil, just that they are impossible for us to see directly. If we can't see it, then how do we know it exists? Imgaine you are looking at our solar system, with the sun in the middle and 8 planets (I know it should be 9, astronomers are a crazy bunch) revolving around it in harmony like normal. Now imagine you cant see the sun, you still see all these planets orbiting around the sun, but you cant see the big thing in the middle that is causing them to orbit that way. That is the idea behind dark matter, although not as specific as that. Looking for actual dark matter is much more difficult, since you can only rely on what you know should be there, instead of what actually is.
Dark energy works in much the same way. Since every star we look at is redshifted in some manner, and the further away it is the more redshifted it looks there is evidence that instead of slowing down (as you might expect at the end of a large explosion) all these stars are actually moving faster. Thus there must be some kind of extra energy, dubbed "dark energy" with a negative pressure. To understand what I mean by negative pressure think about being in an airplane cabin. If someone were to open one of the airplane doors while in flight all of the easily breathable air would escape, since the air is so thin while you are flying. Then we say the air inside the cabin is pressurized, and presents a positive pressure to the outside, it is trying to force its way out. Conversely the air outisde has a negative pressure, it is trying to suck up all of the air from the inside. The same is true for this "dark energy" as it causes the universes' expansion to accelerate.
Next time ill talk further on what people believe dark energy and dark matter to be, and why understanding these forces we cannot see may be the most important step to understanding the formation of our universe.