Cosmology and Our View of the World


Summary of Class session Monday, Feb. 8, 1999

By: Melanie Dodge

Meeting Minutes:

Procedural Information:

The class started out with PEM asking people to start thinking about their topics for discussion. Howard rose his hand and on 3/1 or 3/ 8 will be leading the discussion on the Anthropic Principle.

We then went over how credits were going to be awarded for the class, those who are taking the class for credit will receive one credit in either Philosophy, Religious Studies, or Physics. There was a mix up over at the Registrar's office where they would not let students register for one credit, PEB and PPB will get it straightened out. There is the option to take the class for more then one credit, if you wish to do so, you should go and speak with either PEM or PPB.

Lecture and Discussion:

PEM lead the lecture, the second in the class on Physical Cosmology and the limits of the Universe. First we discussed the expansion of the universe. Hubbles Law: Galaxies are moving further and further away form us, the universe is expanding. The farther the galaxy the faster the speed. We can measure the speed of the galaxy and from knowing the speed that the galaxy is moving away from us we can deduce the distance it is away.

We then watched a video from the Smithsonian on how they measure the speed and the distance, and from that how they can locate the galaxy in the universe, on a map of the universe. It showed how they measure the Red Shift of a hydrogen line called the Hydrogen Spike, the redder the spike, the faster it is moving, and from that they can find out where it is located in the universe.

If thinking about the universe as a globe they have only been able to map out four small slices, roughly in relation to the size of Rhode Island compared to the earth. Galaxies are patterned in the universe like soap bubbles, lumped along sheets of the bubbles, and like a balloon when you blow into it, are expanding.

Is the universe expanding forever, or will gravity one day slow the expansion down so that the universe one-day will collapse again? PEM pointed out that there is evidence that indicates that the universe might actually be accelerating. This is the opposite of what we might have thought. The bigger the universe is the colder it is also. If it were to collapse again it would get hot, it all has to do with pressure and heat that is generated from pressure. And since the universe is still accelerating after around 15 million years, there may be something out there working against gravity that we are not aware of yet.

PEM then discussed how gravity curves space and time, curves the light, and how it curves into a fourth dimension that they are unable to figure out yet.

Next we watched another movie on the geometry of space, and how math is needed to map out the universe. It is linked to the geometry of curved spaces, trying to figure out the shape and size of the universe. In 1918 they measured the curvature of space. Einstein used the equation of relativity, physics of the universe, cosmology, to explain the geometric properties of space, curved space. The universe, they explained was like the earth's surface, if you go long enough in one direction then you will eventually end up where you started from, coming from the opposite direction, and can travel forever and never hit an edge. But there is a finite volume to space.

PPB the asked the question: "Is the universe expanding in a curved sense?" PEM answered that the balloon is only a two dimensional representation, the point is that the pathways are getting longer. PPB and a student then remarked how a balloon is defined by the empty space around it, but in the universe there is no empty space, and that wouldn't it continue expanding and one day end up back where it started.

Next we discussed how the larger the universe gets the more flat it will feel, the less curvature it will have, and we can only see a tiny portion of that space.

We then learned that as we look farther into space we will be able to see farther back in time to the beginning of the universe, looking at galaxies and quasars, a quasar is the center of a galaxy to come, a baby galaxy. We will finally arrive at a point where there are no features to the galaxy, only electromagnetic radiation, and also very hot, around the age of 300,000 years old. We can't see any further back because of the radiation, like the photosphere of the sun where light come from you can't see anything within it.

Theory says that we should still see the afterglow of the big bang, the remainder temp 3K, which is really cold. The background radiation was found and the theory proved from Bell Telephone when they built a big satellite and heard a hiss that was found to be the background radiation.

We then looked at pictures from COBE, which show an idea to the mapping of the universe, the more red, the hotter, the denser, the more energy, a protostructure, a picture of the structure of the universe, where things are just beginning.

We then looked at the independent justifications of the BIG BANG theory.

1. Hubbles expansion

2. Background radiation prediction found

3.Physisists have found cooking recipe and the predicted element

The cooking recipe was H, He, and Li since they are very light and was formed at the beginning of the universe. This was found to be right because we can extrapolate the density in the early universe which determines the He, H ratio that is observed today.

Problems with Big Bang Theory

1. Flatness or Fine Tuning Problem.

The universe is very close to being flat, within one order of magnitude of the decision to ever expand or to collapse, in other words it had to start out with 0.000,000,000,000,001 at 3 minutes magnitude.

2. Horizon Problem.

Universe looks the same in opposite directions, if this is true then these two places would have to communicate many times the speed of light to do this but communications not possible at 300,000 years, which is much farther away than the speed of light.

3. Matter Problem.

There is matter left over in the universe when matter and anti-matter should be an equal amount left and every proton and neutron should cancel each other out, but they don't.

Inflation, the Cosmic Munchhausen Effect takes care of all these problems because of rapid expansion together and doesn't need supraliminal connection. And it expands faster than the speed of light.

This leaves us with the question why is the universe just right for intelligent life to develop. If it were wrong by just 1%all of the hydrogen would have been burned up to helium and we would not have a sun. This is known as the Anthropic Principle.

We are then left with two possibilities.

Strong Anthropic Principle:"The universe is designed correctly to support intelligent life"

Weak Anthropic Principle: "We live in the 1 Universe of many which happens to be the right one to support life.

Science provides no decision between the two. If we do experiments differently we get different answers. There will always be a degree of uncertainty. We cannot separate mind from matter.