Hacker News Reader

Comment by _Algernon_ | Hacker News Reader

Seems silly to try to calculate probabilities from a sample size of 1, but what do I know.

If you have two competing theories, one requiring fine-tuned parameters and the other not, then the latter seems more plausible, because it requires less assumptions. Our universe being “typical” in the context of some theory just means that it requires less fine-tuning, and therefore the theory arguably has more merit.

But the problem is that we have no evidence to suggest that our universe is typical in the first place. For all we know there are a trillion trillion universes and ours is the only one with gravity by some fluke, and we are actually living in the least likely possible universe.

And that's the issue is this model is trying to 'work backward' and justify our universe and it's constants as being mathematically harmonious and 'typical' without having any understanding of what the actual value of 'typical' is.

What I tried to explain is that this is not really about other universes. The logic applies even if our universe is the only one. It is about the amount of seemingly arbitrary assumptions we have to make for the theory to explain our universe.

But we end up having to make other arbitrary assumptions about what happened at the very beginning of the big bang or about multiverses that we have no scientific justification in making. Calling the observed physical constants 'arbitrary' is a very mathemetician-like move. It is true that they are free variables in the sense that they cannot currently be derived--mathematical models of the universe must include these constants as hard-coded values. But the word arbitrary implies that they could have been something else, and we really don't have justification for that.

We write the modeling program and somewhere we write

  FINE_STRUCTURE_CONSTANT=1/137;

It is very tempting to instead write

  ./my_universe.sh --fst=0.007 ...

The code does the same thing, but as far as we know that constant is as invariable and intrinsic to what it means to be a universe as PI is to what it means to be a circle.

It is fun to think about but it can't produce scientific results. It's epicycles, coming up with more complicated stories that over-fit for a singular observation.

> But the word arbitrary implies that they could have been something else, and we really don't have justification for that.

Well, we’re looking for a reasoning that would support that they couldn’t have been something else, and the article is about one way of coming closer to that.

There are really only two possibilities: Either there’s a reason why they are what they are, then we want to find that reason, or there is no reason, then in other words they are arbitrary.

Both theories are assuming that the parameters are tunable. Why would we assume that?

The parameters are “tunable” because we know of nothing that would prevent the parameters from having a different value. The particular values they have aren’t a logical consequence of other known facts, and hence appear to be arbitrary. They are tunable in the sense that if they were different, no logical contradiction would arise. There is nothing that compels them to have the particular values we observe them to have. This means we have no explanation of why they have those values.

But one goal of science is to provide explanations of why the world is how it is. If we can somehow reduce the apparent arbitrariness of a parameter, or remove it completely (by having it be a mere logical consequence of something else we know), then that increases what we can explain about the universe.

How do you know that the parameters are fine tuned from a single observation? Occam's razor still needs multiple observations to create the model.

They are fine-tuned in the sense that we have to postulate them as axioms, due to lack of any further reasons or causes of why they are how they are. The more we can constrain the value space from which the parameters could conceivably have been chosen, the more “typical” the actual values we observe become, and the less remains unexplained.

Sometimes Occam's Razor reminds me a little of that joke about the two economists who notice money lying on the ground.

Do we assume that our universe will turn out to be elegant because that's what we'd most prefer?

In 1000 AD I live on an island of blond and left handed people, therefore the typical human is left handed blond

You’ve missed the point. If genetics would show that blond hair and left-handedness are genetically more likely (more “typical”), that would help explain what you’re observing.

I likely am missing the point, how are we proving the 1 and only sample is typical ? That’s setting aside the whole we have limited observations of the whole universe. Dark matter shrug, dark energy shrug

British may think otherwise.

https://en.wikipedia.org/wiki/German_tank_problem#Historical...

I'm missing where they estimate anything from a sample size of 1. Care to enlighten me?

It was a joke, they didn't but the problem has a formula to estimate the total number from a sample size of one tank, explained in the wiki article under "One Tank" section.

It's theoretical physics. Metaphysically and experimentally, the question may be absurd, but the exercise of calculating entropy for potential universes could still yield novel understandings about the actual universe.

Silly is an excellent word to use when describing a category error, agreed.

Reply on news.ycombinator.com