So, constraints from Big Bang 
nucleosynthesis from type 1A super novae 
surveys from the cosmic background and 
from many other sources have been put 
together into this best fit that tells us 
the parameters of our universe, which I 
used as input for my description of the 
history. 
So, let's see how these parameters are 
put together. 
what we see here is a plot of matter 
density today versus cosmological dark 
energy density today. 
the line here is the line diagonal where 
the sum of the two densities is one. 
Remember, that's total energy density one 
that corresponds to flat universes. Above 
it, we have positively curved universes, 
below it negatively curved universes. And 
these concentric curves are, are curves 
of within which, outside of which you can 
exclude being with increasing certainty 
based on various measurements. 
So, for example, the Super Nova survey, 
remember, was measuring the deceleration 
parameter, if you remember, that 
corresponded to rho plus 3p/c^2 which 
ended up being half of the density of 
dust plus the density of radiation, which 
is irrelevant, minus the density of dark 
energy. 
And so, that's the slope of this graph. 
We get a very good measurement of this 
quantity in this direction, but we get a 
less of a sensitivity to the sum of this 
plus that. 
Because if you increase the matter 
density and also increase the dark energy 
density, the deceleration parameter 
doesn't change much. 
So, the supernovae give us a good 
constraint in this direction but now much 
in this direction. 
On the other hand, the cosmic microwave 
background data is pretty much sensitive 
to the total density. Remember, we 
measure the flatness of the universe, it 
lays us pretty much on this line. 
Happily, these two are crossed and so 
between them they produce a very good 
prediction. 
this is additional data sensitive mostly 
to the density of dust because this has 
to do with looking at the galactic 
distribution and corelations in distances 
and that's similar to the way we studied 
the acoustic sound waves in the 
primordial plasma. And again, this is 
supposed to track the wavelengths and 
fluctuations in the dark matter density. 
And so this gives us a third and 
consistent constraint. 
There are many other observations that go 
into the pot when making our best 
estimate, but you see that we have both 
consistent and rather precise 
determination of the parameters of our 
universe, and you see that we predicted 
arc energy of about 0.75 of the critical 
density and a matter density of about 
0.25 of the critical density, of which, 
remember, we have restrictions, let's 
say, at most 5% is visible matter, so the 
rest are baryonic matter. 
That's from among other things, 
baryogenesis and also the details of the 
cosmic microwave background. 
So, we predict that the rest is dark and 
we do know exactly what our universe is 
made of. 
That's quite exciting.