# Fundamental parameter probabilities

1. Jun 8, 2009

### Pjpic

What are the odds that any particular big bang will result in the 20(?) fundemental parameters having the values that will allow life to form?

2. Jun 9, 2009

### Chalnoth

Given as we don't yet have a theory of everything, we can't yet say what the relationships between the various parameters are (in full). Furthermore, we don't yet know how many such "big bang" events happened. So even if the probability for any single big bang event forming life is, for example, 10^-200, if there are in excess of 10^400 big bang events, then it's no problem.

Finally, it is worth mentioning the simple fact that we wouldn't exist if life weren't possible. A simple tautology, but worth pointing out, because it demonstrates that we can't infer anything at all about the habitability of the universe: no intelligent being can possibly observe a universe that isn't habitable.

3. Jun 9, 2009

### Pjpic

So even if the probability for any single big bang event forming life is, for example, 10^-200,

Is 10^-200 ballpark given what we know?

4. Jun 9, 2009

### Chalnoth

No. It's just a random number I threw out there. There is no way to say at the current time, because we don't yet know what the probability distribution of possible outcomes of big bang-like events is.

5. Jun 9, 2009

### apeiron

The odds are likely to be very close to either 1 or infinity. Either only one universe was the most probable outcome - and we can see that it is our own and supports life. Or there must have been a near infinity of goes at producing universes, and we just happen to be in the lucky outlier.

The two perspectives can be combined of course. As in evolving multiverse scenarios where from infinite variety there is a gradual evolution by replication towards maximally complex universes.

So Bayesian approaches would rule out much of the middle ground of probability and favour the opposing extremes I suggest.