Monkey Shoot

All elements make their own special characteristic colors (called spectral lines)

Once you identify the element responsible for the lines you see, you can measure the redshift

Conservation of angular momentum

Explains why neutron stars spin fast

These make good clocks

We use the best of these to look for a remnant of “gravitational radiation” from the inflation era

It’s really, really cold in deep space

Demo of how cold 77 K (liquid nitrogen) is (deep space is 3 K!)

The BB doesn’t really say why started out hot or expanding but:

• The model is consistent with this much of the data.

• Using only laboratory physics• We already know some problems: smoothness

of CMB, CMB fine structure, SNe Ia, and clusters. But some say we need more => enter Inflation:

Inflation is motivated by: Problems with the standard Big Bang model. But, “why make big problems out of little ones!!” [you be the judge]

• Why T the same on opposite sides of the Universe that were never in “casual” contact [never touched each other or able to communicate via light]?

• Why is the value of “so close” to 1 without being 1?

• Why did we have an initial relative range of density fluctuations in the “brick wall”?

• Or, why does the CMB have power versus angular scale) that is does?

• Why was the initial Universe so hot?

• Or, why so many more photons [bundle of light; quanta] than particles? [ high number density of photons relative to particles! means high energy density relative to particles = hot.]

• Why aren’t there more magnetic mono-poles as predicted by GUTs?

What Is Inflation?

• The Universe started with the decay of black hole of about 105 grams, that decayed in 1043 seconds, and a size of 1033 cm.

• The Universe at this time was then filled only with this “vacuum” energy.

What Is Inflation, cont.

• We’ve already derived that this will expand exponentially (empty universe k = 0).

• It doesn’t take long for this expansion to become faster than the speed of light.

• The result is that portions of the universe that appear as though they could have never communicated via light, did so prior to inflation.

What Is Inflation, cont.• This means these portions of the Universe had

time to communicate to each other that they should had the same T (at least before inflation starts).

• A FAQ is: How can anything go faster than the speed of light?

• The answer is: the objects themselves aren’t moving, but rather it is only the surface that is moving.

What Is Inflation, cont.• It’s OK if you don’t like this concept as I

don’t either. The “high priests” in the field of Particle Astrophysics say: “it is so.”

• Next, the “cosmic coincidence”:• Or, how can be relatively close to 1, but

not 1?

The concept is, if we look at my meter stick as it falls over, isn’t strange that you just happen to see it in mid-fall as you walk into the room?

What Is Inflation, cont.• Rather you are more likely to find the ruler on the

ground or balanced perfectly, but not in mid-motion.

• The idea then is, if started out above 1, then it very easily could have, by today evolved to such a huge number the Universe should have collapsed on itself by now.

• And if the Universe started out less than 1, it would have evolved to such an empty Universe by now, there would be no distant galaxies visible.

• Equation for as a function of z => (1+z)1 = (01)/[1-0+/(1+z)2 +m0*(1+z) ] => as z becomes large the right hand size goes to zero. If = 1, then the right hand side is always zero. Here (1+z) means as a function of z and the * means “times.”

• That now we have observations that are consistent with t = 1, this gives credence to INFLATION

• Or, this is why many keep looking for ways to make their results consistent with t = 1!

• Since GUTs doesn’t work, however, this is mute point.

• Originally, GUTs was the logical extension of particle physics theory to “super-high” energy (kT = k1033 K) that applies to inflation

• GUTs predicted lots (too many for observations) magnetic mono-poles, inflation was nice because it “inflated” away, or made the universe extremely dilute (to agree with observations) in magnetic mono-poles