**Cosmology and our View of the
World**

**The Anthropic Principle****,
Lead: **

**2/20/2006**

**Summary by George Clark**

Sara Maltais and Kyle Wilson started off their presentation by handing out a work sheet that defined the four fundamental forces, the two Anthropic principles, and had questions, such as what if the values changed in the universal constants, for us to ask ourselves. Kyle W then started to make an outline of the big bang by using a time line. The outline is as follows:

- after one second there was an enormous expansion rate

- after 3 minutes nuclei of hydrogen and helium formed

- after 300.000 years the universe started to cool down enough to allow atoms to form

- and after 300 million years galaxies and stars started to form.

Sara M and Kyle W defined the four fundamental forces as follows:

- Weak force: the force responsible for nuclear decay, such as beta decay.

- Strong force: The force responsible for holding together the protons and neutrons in the nucleus of an atom.

- Gravity: The natural force of attraction between any two massive bodies.

- Electromagnetic: The physics that combines the forces of electricity and magnetism.

Sara M and Kyle W then started to explain that if there were small changes in the strength of the fundamental forces relative to each other, there would be no life as we know it today.

Sara M and Kyle W then defined the weak and strong Anthropic Principle for us.

-Weak Anthropic Principle: The properties of the universe are such that conscious observers can exist.

-Strong Anthropic Principle: The Universe must have those properties which allow life to develop within it at some stage in its history.

Kyle W brought to our attention that if we were to flip a coin 10 times, then we would have a 50% chance of it landing on heads and a 50% chance of it landing on tails. Therefore by the weak Anthropic principle, if we were to toss the coin enough times, it would be possible for either head or tails to land 100% of the time for a large number of tosses in a row. In contrast, the strong anthropic principle states that it cannot be chance – the universe must have been designed so life can occur.

Kyle L started off by asking if the strong principle promoted a God.

Kyle W informed us that, no; it does not promote a God. The universe has been designed for life and nothing else can be any other way (basically just re-stated the definition of the strong principle).

Morgan then brought up a good point about the six numbers (these six numbers are defined in our readings, “Just 6 Numbers”) such as: Ω (the ratio of actual density to critical density), L ( Einstein’s cosmological constant), N (the electrical forces that hold the atom together divided by the gravity between the atoms), Q ( the ratio of gravitational binding energy and its mass energy), D ( the number of spatial dimensions), e (nuclear force constant relative to the strong force) and wanted to know about their values being tweaked. Since the topic was being focused on just a few constants and their alterations, Morgan wanted to know what about these six numbers and their importance to our universe. The Weak Anthropic principle states that our universe is fine tuned and that any alteration of these constants would result in a radically different place.

Kyle then mentioned the importance of protons, neutrons, and other particle / antiparticle relationships that were involved for the big bang to take place.

Morgan then asked whether the anthropic principles allow other forms of life to fit in.

Dr. Möbius then explained the very delicate balance of the constant values. He said that if the gravitational force were to increase 1-2% relative to the strong nuclear force and vice versa, then in the beginning of the universe all the hydrogen would have burned up into helium. If you were to go the other way, then to get two protons to merge into deuterium would not happen in Sun-like stars. This would then result in the stars not being able to undergo reaction. He said it only takes a few percent in the ratios to produce a starkly different result.

The discussion then started to lean towards the constants where Dr. deVries and Dr. Davis were talking about results and probabilities.

Dr. deVries mentions that the constraint on scientific principles should not produce results. For example, we cannot say gravity has to be this strong to ask about what it is. Instead, we evaluate what gravity is by being able to observe how it affects our physical world.

Dr. Davis went on to explain that we’re in a universe where 1000 throws of a coin came up heads. He continued to say that we have no evidence to prove it had two sides that it could have been just a one-headed coin. He also stated that the constants could have other values and asked how we can test for these other values.

Tamsyn jumped in and had a pretty good answer for Dr. Davis. Tamsyn explained to us that we can not test what was before then, we can only test the possibility {within our universe?} because we cannot physically go back to that time – we can’t go back to the big bang. We are only allowed to ask the questions. She was trying to seek an alternate way to test for the principle.

Dr. Möbius came in with a great analogy about how we are able to observe. Dr. Möbius stated when looking at the sun we can only observe it at its surface and outer layers. We cannot look inside the sun, but we can measure the parameters, size, mass, etc. To figure out that energy has to be generated there has to be nuclear fusion. Theories say we should be able to observe neutrinos from the nuclear fusion process as a product of the proton proton chain.

Martin came up with a great point by asking if the constants were always the same or if they could change in the future.

Dr. Möbius replied over the past 13.7 billion years (age of universe)
there has not been any significant change in the values of the constants. If
in the future, there were to be a change in any of the values then it could
be surmised from a trend of data collected in the past. At least to date the
constants have always remained the same. There are levels of explanation: i.e.
explaining why it rains to a 3rd grader as opposed to explaining it to a PhD
student.

There should be a “right” answer whether you’re explaining
it to a 3rd grader or a PhD student.

Sam S. asked, since the model doesn’t allow it, does that mean that it is not possible.

Dr. Möbius then replied that we can never be sure of our model staying intact, because someday someone can prove it wrong. He said this is because of theories in the past that have first been thought to be right but over time were proven wrong.

After this point the class spent a good 30-40 minutes talking about the definitions of the strong and Weak Anthropic principle. They were using examples of tossing coins, the probabilities of tossing coins, and whether the strong principle suggests design of some type. The three professors: Dr. Möbius, Dr. deVries, and Dr. Davis contributed most to these discussions with analogies using quantum mechanics, coins, and other things to help define the two principles. Dr. deVries referred to the text and called us to pay attention to the actual words the author uses, which could mean something else.

DJ, in my opinion, was thinking out of box when he stated that this whole coin model is not a great model because it only offers two possibilities….head or tails.

And Jimmy followed up with saying that we should take in consideration that we do not know how many universes there are and there could be life elsewhere. After Jimmy’s comment the class started to graze the topic of multiple universes and quantum theory, which lead us to talk more about probabilities and the definitions of the weak and strong principles.

After some discussion Morgan seemed to bring up a wonderful point that helped shed some light on the definitions. She said that the Weak Anthropic principle would imply that everything is improbable, but actually it’s a cause and effect of one thing being improbable. So you flip the coin a 1000 times or whatever and the universe takes place after the chance of the coin toss and the events after that are of cause and effect of the initial start.

Then the class started discussing about whether or not these constants are the same before the big bang or whether they were set that way after the big bang. The main reason this was brought up is because if the constants are the same before the big bang, then all big bangs are the same and every universe must be sustainable for life to evolve. It would be exactly like our universe. Ben then brought up a good point by saying that if we were to rewind everything to the initial point of the big bang and try and go further back in time, physics, as we know it, would break down, and we would have no way of knowing about the constants before those initial times.

The discussion after this was very much alive and still roaring but I, unfortunately, had to leave at 8pm. I apologize to those that participated after this point that I did not record what you had to say. Therefore, the conclusions they came to, if any, are still unknown to me but I am sure we can make a well educated guess following the trend of the topics brought up in earlier discussions.