PDA

View Full Version : More than one Fraser and Pamela? Really - Episode on how big the universe is



platowannabe
2008-Mar-26, 07:27 PM
A few weeks ago, it was stated on the podcast that if the universe is infinite, you get the situation where eventually you will have other worlds that have a Pamela and Fraser on them.

I do not think that this is necessary (or likely for that matter). Even given an infinite universe, repetition is not required. Take the number line, you can have an infinite series of even numbers.. To achieve an infinite amount, you DONT have to include odd numbers or allow repetition.

Of course, a number system is by definition non-repeating. In the universe, its definitely the case that the situation CAN arise again, meaning the
probability is not 0. In fact, isn't it the case that the probability of an identical world is non-zero even if the universe is finite?
By believing in repetition, we are assuming a finite number of possible chain of events could occur, leading to a required repetition (deeper philosophical question, if all
things are exactly the same (even quantum state) are they in fact different
planets or the same planet?).

I guess the question comes down to the question are their a finite number of
possible arrangements of matter in a universe which requires the assumption
that the infinite Universe is uniform (same laws as we see them apply
everywhere rather than variations over certain ranges, which I think is
reasonable considering we have yet to see anything to the contrary).

Steve Limpus
2008-Mar-26, 08:14 PM
I think the reasoning goes like this:

In an infinite universe, everything that can happen, will happen, infinitely.

But then what do you do with the idea that there are an infinite number of things that could happen? How does that fit in an infinite universe? Each of those Frasers and Pamelas could just as likely be infinitely variable (a freckle here, a fingerprint there) so they're not really our Fraser and Pamela? Like you said.

I can't help but feeling the idea of infinity is bogus - for maths, sure; but for reality? I'm not buyin' it.

But if not infinity, what else instead? If finite, what about other dimensions?

:eh:

Why is there something rather than nothing?

:wall:

platowannabe
2008-Mar-26, 09:22 PM
The idea that everything that can happen, will happen I guess is where I just don't agree. I don't see the need for that premise with infinity, and I wonder if there is any mathematical reason to believe this OR if this is just an example of the human mind getting stuck on something that the human mind was not designed for.

platowannabe
2008-Mar-26, 09:53 PM
Fraser was nice enough to send me this link : http://space.mit.edu/home/tegmark/multiverse.html

has some things that help me understand what he was saying.... however I'm still Skeptical.

This may be based on a bad understanding of probability when applied to anything beyond the realm of chance we deal with in every day life, but consider.

There is a small but existent probability that the location of a particle when its wave function collapses could be in the Andromeda galaxy rather then in our lab where we expect it. Correct?
Now, does this mean that at some point now or in the future a particle will defy the odds and show up there? or that if enough humans start walking at walls for a long enough time we will eventually pass through it? I think if we started either experiment and let it run for an infinite amount of time it still would never happen. We think it would because of an understanding of statistics, "well, its possible, so it will eventually happen". But in reality the system is biased against those outcomes.

Complex systems have a similar situation.. There may be an infinite number of complex systems out there, each with a almost infinitely high improbability of occurring EXACTLY as we would define it. Human life as it stands now would have a very high improbability of occurring, where the situation on Mars would have a higher probability. If Evolution had a direction rather than the function of dealing with environmental issues, then perhaps our probability would be higher, but its the conditions over 13 billion years that lead up to us since if the metal content of our solar system were different the environment would be different (if it was even open to life).

More simple situation, our definition of statistics says that if I flip a coin, overall I should be around the same number of times heads as tails after a sufficiently high number of flips. I could work out the statistical probability of flipping 2000 heads in a row, and it exists. But if I do it for all eternity all we are saying is there is a chance it could happen, not that if we wait long enough it WILL happen.

Final example is all the gas in the room moving to the left side and me suffocating.. Statistically possible? Sure.. Will it happen? Nope.. the system is biased against that.. I would think its unlikely that anywhere in the universe there is a vacuum created for any large size just based on random molecular movement . Its not impossible, but its also possible that it will simply never happen.. statistics be damn..

Ok.. my brain dump is done.. please point out the holes if you see it and help me understand this thing..

Steve Limpus
2008-Mar-26, 10:11 PM
The second scenario I think.

We didn't need to comprehend infinity to catch Mammoths or dodge Sabretooths - so we can't. But we have done rather well all things considered. :)

platowannabe
2008-Mar-26, 10:13 PM
Darnit..
Somehow my long post didnt make it.. figures..
Retyping and condensing:

I guess this comes down to 'because something can happen, will it happen in an infinite universe' or is it possible for something to happen once and only once if it has a high enough probability.

Probability is such a odd thing for us to deal with since we are wired for certainty.. and maybe I am having a hard time getting past my programming.. But I also feel like this question is one that is mathematically created and not one that needs to link to reality.

Consider: If I flip a coin an infinite number of times, there is a probability that it will come up 20000 times in a row. It is HIGHLY improbable but none the less not impossible. If we conducted this experiment would it eventually happen? Or another example of someone passing through a wall because of the perfect alignment of their quantum state. Possible? Yes.. Likely? no.

Systems like Human evolution (i'm not being human centric here, I'll even say a planet with my pet turtle has the same likely hood as me) are highly complex and the exact result does not have bias to the form. Given the exact same environmental conditions, its highly unlikely that humans would form even on this planet.. its random natural selection..

The fact that there is a non-zero probability of an event occurring does not seem to imply to me that there is a probability of 1 that it occurs somewhere.

I'm either too Dense, too Sane, or too much of a skeptic.. and when dealing with the concept of Cosmology, maybe Sanity is a drawback (need just a little insanity to get you to think further out of the box)

platowannabe
2008-Mar-26, 10:15 PM
The second scenario I think.

We didn't need to comprehend infinity to catch Mammoths or dodge Sabretooths - so we can't. But we have done rather well all things considered. :)


Very true..
I like to imagine an alien race watching us on some sort of intergalatic tv show.. and the Title is "Primates say the darnedest things!".. Bill Cosby could host.

Steve Limpus
2008-Mar-26, 11:35 PM
I could be on that show! :lol:

I find cosmology perfectly sane to a point - then it just keeps me awake nights.

Over on the Q&A forum I've raised the infinity thing a couple times, but not got a lot of feedback. I think some of the people who have been here a long time have thrashed it over many times and probably found it pretty unproductive.

And as much as our intuition can serve us poorly, I still feel that the universe will turn out to 'make sense'.

Nature isn't about to let us walk through walls any time soon.

Wouldn't it be cool if when you die someone taps you on the shoulder and says "Well dude, how was that?" and then takes you off for a long cold beer and a chat...

Dumbledore perhaps. ;)

clint
2008-Mar-27, 10:42 AM
Wouldn't it be cool if when you die someone taps you on the shoulder and says "Well dude, how was that?" and then takes you off for a long cold beer and a chat...


My grandfather once told me of a dream he had:
in that dream he died and found out that all his long-dead war buddies
were already waiting for him and welcomed him with a cold beer :)

platowannabe
2008-Mar-27, 04:54 PM
So, I've thought about it over night, and I have a clearer way that if someone can point me to the right information, this may make me accept (and perhaps understand) this idea.

- There is a VERY low probability that the world as it exists now would have occured as it exists now (life, geography, etc).
- Given an infinite universe with a finite number of Quantum States, it becomes more likely to recur exactly as it is than an infinite universe with an infinite number of Quantum States for each particle.

But, As the size of the universe goes onto infinity, does the a graph of the probability of an infinite number of 'other earths' approach 1 or does it just get closer and closer (zeno's paradox like) to 1?

......

As I write this.. forget it.. My mind has been broken by the function of infinity.. I would think a safe proposition to take would be 'The repetition of events in an infinite universe is un-avoidable, the repetition of a particular event is probable.' and leave it at that. The statement that there is another me out there is possible, and maybe even probable, but not something we can validate experimentally (yet).

Anyone recommend any good books on the mind-benders of infinity?

Steve Limpus
2008-Mar-28, 07:01 PM
The problem, I think, would be that no book on infinity would be any more definitive than your own ideas. Entertaining, sure. But would you 'know' any more in the end. I doubt it. Zeno probably covered it all - and you still can't get good odds on the tortoise. :)

Steve Limpus
2008-Mar-28, 07:17 PM
Clint,

let's start the 'Church of Long Cold Beers' - I reckon it'll get more traction than anything L. Ron came up with. :)

My grandfather served in the Western Desert, drove an ambulance. Never talked about it, far as I know. If anyone deserves a divine beer, the old soldiers do.

Steve Limpus
2008-Mar-28, 08:19 PM
Given an infinite universe with a finite number of Quantum States, it becomes more likely to recur exactly as it is than an infinite universe with an infinite number of Quantum States for each particle.

What about this:

Even where there are a finite number of Quantum States, where there are infinite particles, finite states multiplied by infinite particles will still equal infinite outcomes. Since infinity equals infinty, there is no 'room' for duplicate Frasers and Pamelas?

Steve Limpus
2008-Mar-28, 08:29 PM
Anyone recommend any good books on the mind-benders of infinity?

...just remembered a favourite old link:

http://news.bbc.co.uk/2/hi/programmes/documentary_archive/5349064.stm

http://news.bbc.co.uk/2/hi/programmes/documentary_archive/5349364.stm

Well, yes two actually. So don't trust my math...

clint
2008-Mar-28, 09:49 PM
Clint, let's start the 'Church of Long Cold Beers' - I reckon it'll get more traction than anything L. Ron came up with. :)

Where can I apply, I want to join today :D

damian1727
2008-Mar-29, 09:08 PM
cheers

dcl
2008-Apr-24, 12:47 AM
There is a lot of loose thinking afoot regarding the nature of infinity. I've decided to go on record with some facts:

There are just two conditions under which the Universe could be infinite in extent:

. (1) Its expansion rate must have been infinite over at least some infinitesimally brief interval of time,
or
. (2) The Universe must have been expanding over an infinite period of time.

The Big Bang theory assumes that neither of these conditions was met.

Even if the Universe were infinite in extent, it still would not follow that there must neceessatrily be duplicate copies of anything in the Universe. There could exist, for example, an infinite number of different things. There COULD be duplicate copies, but it is not necerssary that there be.