Prob(being in a typical universe)

[T'ai Chi]

http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2630v2.pdf

A very thought provoking look at some probability.

[Dilb]

Pretend, for a moment, that this is a public forum, accessible by anyone with an interest in the fields of science, mathematics, medicine, and technology. What should a layman, such as myself, a mere physics student, get from this very dry paper on the application of Bayesian probability, steeped in technical terms and formality?

I can read the abstract, but this makes the rather uninteresting claim that we don't have a good reason to suppose we are typical observers in the universe. This seems relatively uncontroversial, so perhaps you could write some sort of short note, viewable to everyone, on why you feel this paper is, dare I say, interesting?

[l0rca]

http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2630v2.pdf

A very thought provoking look at some probability.

I think this is a key difference between you and I (at least myself):

You regard speculation as thought-provoking and convincing.

I regard evidence as thought provoking and convincing.

[Jeff Corey]

At least this one was "very thought provoking" rather than merely "interesting".
See, folks, the usually incredible banal can be prompted to come up with relatively novel responses, if prodded enough.

[Lord Muck oGentry]

http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2630v2.pdf

A very thought provoking look at some probability.


Universes are not as plentiful as blackberries C S Peirce

[T'ai Chi]

What should a layman, such as myself, a mere physics student, get from this very dry paper on the application of Bayesian probability, steeped in technical terms and formality?


You're asking me what you should get from it? How is anyone, other than yourself, supposed to ascertain that?


, so perhaps you could write some sort of short note, viewable to everyone, on why you feel this paper is, dare I say, interesting?

I reject that "idea". People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.

[T'ai Chi]

You regard speculation as thought-provoking and convincing.

I regard evidence as thought provoking and convincing.

Most people who are educated regard math as logic rather than "speculation".

[Mercutio]

No argument with the paper here. In their conclusion, I wholeheartedly agree that "there are no observational data supporting an assumption that we are typical in some class of observers" (I also point out what they do not, that there are also no observational data supporting an assumption that we are not typical), and agree with them that we should make our assumptions explicitly, so that our assumptions as well as our conclusions are available for review.

This is completely consistent with a number of posters here (I am thinking of Stimpy more than any other) who may be misunderstood simply because they *do* acknowledge their assumptions (and others'), and are arguing against people who don't even recognize that their arguments are based on particular assumptions.

[Mercutio]

Most people who are educated regard math as logic rather than "speculation".

I had hopes that this thread would not just be sniping...oh well. So, TC, what about the paper would you care to discuss? I am overjoyed that you are working to understand bayesian inference now.

[Dilb]

You're asking me what you should get from it? How is anyone, other than yourself, supposed to ascertain that?

Well, you could point out interesting sections, and explain them in ways that people can understand. Perhaps invite people to comment on the authors' opinions. A good one might be
At present, there are no observational
data supporting an assumption that we are typical in
some class of observers, and our understanding of biolog-
ical evolution is insufficient to supply a theoretical justi-
fication through the likelihoods.

It's not obvious to me how they come to that conclusion. It seems like a rich area of discussion for biologists and astronomers. Meanwhile, the bulk paper is about statistics, and I don't understand why equation 4.1 implies there is no preference for the typicality of humans, because I have no idea what equation 4.1 means.

Totally understanding all the details of a scientific publication isn't the sort of task I expect random strangers to undertake.

I reject that "idea". People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.

So, you've confused this forum with a math department, and confused yourself with the mail clerk? If you were anyone else, I would simply have never looked over the paper, because it doesn't interest me at all. The last paper you linked to that I read (actually, it was a chapter from a book), contained such a blatantly incorrect interpretation of math that I shudder to think an actual professor wrote it. I looked at this paper to see if it was claiming statics prove evolution must be wrong, but it seems pretty reasonable. As a result, I have no inclination to read it, just like I'm not going to read any of the other ten thousand journals I have access to.

If you wanted to discuss Bayesian theory, a simple note in your first post would have first allowed people to avoid this topic, should they not want to talk about statistics, and second, allowed you to actually have a discussion with the people who do understand statistics.

[andyandy]

http://arxiv.org/PS_cache/arxiv/pdf/...704.2630v2.pdf

A very thought provoking look at some probability.

well, for once it was interesting - although the conclusions don't appear especially controversial.

[Zep]

I thought the layout and the typeface were interesting too, TC. As was the number of headings and footnotes. I'm sure this means something to a statisticool like yourself. But it means sweet FA to anyone else.

[Gord_in_Toronto]

At least this one was "very thought provoking" rather than merely "interesting".
See, folks, the usually incredible banal can be prompted to come up with relatively novel responses, if prodded enough.

Well I thought it was "itneresting" (qv). :D

So there! ;)

[TV's Frank]

Honestly, this paper was interesting to me. Whenever string theorists start talking about "the landscape", and how our universe is just 1 out of 10^600 (or more) possible universes, they claim anthropic selection for the observed values of physical constants (i.e., if there was too much dark energy then the universe would expand too much before structure could form, hence no life would form, hence no observers etc etc). However, any statement of anthropic selection assumes that we are likely observers. This paper says, "no, we aren't necessarily likely, so you string theorists when you write a paper make sure you list your assumptions."

Just for the record, as far as I know, the only cosmologists who like "the landscape" and string theory are....string theorists.

[Dr Adequate]

Honestly, this paper was interesting to me. Whenever string theorists start talking about "the landscape", and how our universe is just 1 out of 10^600 (or more) possible universes, they claim anthropic selection for the observed values of physical constants (i.e., if there was too much dark energy then the universe would expand too much before structure could form, hence no life would form, hence no observers etc etc). However, any statement of anthropic selection assumes that we are likely observers. This paper says, "no, we aren't necessarily likely, so you string theorists when you write a paper make sure you list your assumptions." This, I think, is the summary that Dilb wanted.

[Bob Klase]

A very thought provoking look at some probability.


So what thought(s) did it provoke in you?

[T'ai Chi]

People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.

[Darat]

People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.


It's called having a discussion - look at the strap line in the header of the page "a place to discuss...", if you don't want to discuss this isn't the Forum for you.

[T'ai Chi]

I'll decide if it or is not the forum for me, thanks for your comments, which will be given high consideration, as usual...

Discussion does not mean the same thing as 'you must post your comments'. What about the distinction confuses you?

[Darat]

...snip...

I also point out what they do not, that there are also no observational data supporting an assumption that we are not typical)

...snip...

Is that actually the case? Surely we can state that the observational data indicates we are not typical? We only need to look at the Earth and we can see that "life" itself (as we know it of course) is only possible in a minuscule volume of the whole planet's volume and we can observe that "life" cannot exist in 99.9999999999999999% (and probably a lot lot more 9s) of the volume of the universe we can observe?

Or am I falling for the "no evidence isn't.." fallacy?

[Darat]

I'll decide if it or is not the forum for me, thanks for your comments, which will be given high consideration, as usual...


No you won't - the JREF will.


Discussion does not mean the same thing as 'you must post your comments'. What about the distinction confuses you?

Why should anything confuse me about that, I've made no comment about anything to do with that distinction.

Now can you stop posting about your opinions of other Members and yourself and get back to the topic of the thread, which as far as I am aware is not you or other Members? Your constant derailing of your own threads into personality issues rather then the subject under discussion is getting rather tiresome...

[CFLarsen]

People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.

Yet, you have no problems asking for other people's opinions and thoughts.

Is it because you don't have any yourself? You are completely empty inside?

[Mercutio]

Is that actually the case? Surely we can state that the observational data indicates we are not typical? We only need to look at the Earth and we can see that "life" itself (as we know it of course) is only possible in a minuscule volume of the whole planet's volume and we can observe that "life" cannot exist in 99.9999999999999999% (and probably a lot lot more 9s) of the volume of the universe we can observe?

Or am I falling for the "no evidence isn't.." fallacy?
You have simply taken it one step beyond the level of my assumptions. Certainly, we exist on the tiniest of islands in an unimaginably vast expanse of nothingness and/or hostility. I should have prefaced my statement with a "given that an observer exists", which takes into account your observation that over the vast majority of what we can observe, there are no observers but us. We cannot know that we are typical observers, but we cannot know that we are not. We are one data point.

[Darat]

You have simply taken it one step beyond the level of my assumptions. Certainly, we exist on the tiniest of islands in an unimaginably vast expanse of nothingness and/or hostility. I should have prefaced my statement with a "given that an observer exists", which takes into account your observation that over the vast majority of what we can observe, there are no observers but us. We cannot know that we are typical observers, but we cannot know that we are not. We are one data point.

So is there any amount of observation that would mean we could say we are non-typical?

[Civilized Worm]

People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.


Just as I suspected, you don't understand it yourself but you thought it might support your views.

[strathmeyer]

Most people who are educated regard math as logic rather than "speculation".

Is Fermat's Last Theorem true or false? Please use only logic and not speculation.

[Mercutio]

So is there any amount of observation that would mean we could say we are non-typical? Depends on your assumptions, I would suppose. We are clearly non-typical (inasmuch as we can observe) if "we" is life as opposed to non-life. Given life, we are clearly non-typical (inasmuch as we can observe) if "we" is sentient, observing creatures as opposed (to the best of our knowledge), say, to beetles and bacteria. Given sentient, observing creatures (and now we are beyond where we can observe), we may or may not be typical, which was the level of analysis of the paper.

The "inasmuch as we can observe" is an assumption, of course; it could be that just out of reach of our view is a place where everything is alive but a few non-life things...

[andyandy]

Is Fermat's Last Theorem true or false? Please use only logic and not speculation.

it's true.

The proof is here (http://math.stanford.edu/~lekheng/flt/wiles.pdf) :D

[fuelair]

You're asking me what you should get from it? How is anyone, other than yourself, supposed to ascertain that?



I reject that "idea". People can read the paper and get what they get from it. No need to bias that experience with detailed thoughts from me.

For my purposes, I do not bother going to these things without info about why it is reasonable or to my advantage to do so. Nor do I callously send others to places this way without some semblance, other than I liked it, of reason to do so. Arrant nonsense.
:jaw-dropp

[Tief]

Most people who are educated regard math as logic rather than "speculation".

The process of mathematics is logical, but the assumptions one bases an argument on can be speculation.

Are there areas of mathematics that not all mathematicians agree upon? Meaning, for example, are the people who think string theory is incorrect agreed in the mathematical processes involved in describing the theory, arguing against only the assumptions, or is there a difference in opinion about how the mathematical processes themselves are applied? Are there processes applied that are not agreed upon by all mathematicians? If this were the case, I would say that our understanding of the universe that can be described mathematically is not only skewed by our assumptions, but on what we perceive to be logical.

[T'ai Chi]

Is Fermat's Last Theorem true or false? Please use only logic and not speculation.

It depends on whether you believe Wiles' proof or not.

[strathmeyer]

it's true.

The proof is here (http://math.stanford.edu/~lekheng/flt/wiles.pdf) :D

Can you prove that the link contains the proof, or are you just speculating that it does?

[andyandy]

Can you prove that the link contains the proof, or are you just speculating that it does?

Proofs are not subjective. Whether something exists as a proof is not dependant on whether a given individiual can understand it. Wiles' proof is well established within the mathematical community - and as such if you wish to suggest that this proof is not in fact true, then the burden of proof is on your shoulders to show the error. Otherwise, you are speculating from ignorance.

Here's a simple statement;

if f is a constant function, f(x)=c, then f'(a)=0 for all numbers a.

which is true - and can be proved.

$$ f'(a)= \lim_{h\to 0}\frac{f(a+h)-f(a)}{h}=\lim_{h\to 0}\frac{c-c}{h}=0

The fact that a given individual can not understand the proof does not mean that the statement is false. Proofs are absolute not subjective.

[Darat]

Depends on your assumptions, I would suppose. We are clearly non-typical (inasmuch as we can observe) if "we" is life as opposed to non-life.

...snip...



Aren't you making a rather large assumption even within that statement i.e. that there is difference between life and non-life? I would say that there is no evidence that life is anything but a vague human descriptor for some types of processes. So if we throw that assumption out we can re-cast the question as something like "Are the processes we are interested in typical or non-typical?" - I would then say we can use the observational data we have to say that (so far of course, all conclusions being provisional) the processes are non-typical.

(Aside - why wasn't the term atypical used by the way - I much prefer it).

Or have I still got an assumption tucked away that I'm failing to notice? (I'm ignoring the big ones like - "there is something", "we're not a simulation" and so on - that way just ends with us being unable to make any meaningful statements about anything at all.)


I know I'm moving away from a direct discussion of the paper now but since the thread starter isn't interested in discussing it I can't be excused of thread hijacking.

[andyandy]

Are there areas of mathematics that not all mathematicians agree upon? Meaning, for example, are the people who think string theory is incorrect agreed in the mathematical processes involved in describing the theory, arguing against only the assumptions, or is there a difference in opinion about how the mathematical processes themselves are applied? Are there processes applied that are not agreed upon by all mathematicians? If this were the case, I would say that our understanding of the universe that can be described mathematically is not only skewed by our assumptions, but on what we perceive to be logical.

This is concerned more with the application of mathematics to real world situations - ie physics.

[Taffer]

I'd say, Darat, that when asking "are we non-typical" it must be in relation to something else. In other words, if you say "is life on earth un-typical for the universe", one would be forced to give a definition of "life". In which case, it doesn't matter if the universe does not distinguish between life and non-life.