I brought up the short story because that is where the idea came from, I read it when I was a teen and it was something out of the 60's I think. May have been Fredrick Brown, I'm not sure.

As far as all these universes being similair to our own I'll try to look up that article. It seems like something about it was posted on the forum here at one time. Something in the "multiverse" theory, it can be read up on wikipedia.

edit: but untill then, could you explain why a countless amount of universes (lol that does not sound right) all within a single universe could not have completely differing properties from the universe they are in. I'm not saying all the universes in that one would all be different from each other, only different from the yea..you get it.

So are you identifying galaxy=universe? It sure looks that way to me.

The thing is that that identity has been pretty much out the door since about 1930 or so. It would be trivial to get the exact date if that matters.

Basically, prior to 1930, astronomers had a few ways of measuring the distances to other objects. The one that was most relevant to this topic was the method of identifying variable stars in the globular clusters. There is a clear relationship to the peak apparent magnitude of a variable star and the period of it's pulsations. From that we can work out the distance to the star.

Given that much we knew just about a good rough estimate for the distance to the “farthest stars”. Beyond that, there just did not seem to be anything going on or at least that was the then current thought.

What we now call galaxies were believed to be inside of the milky way. Then Edwin Hubble found a variable star in M31 (Andromeda). From that, he was able to calculate that the star was much farther than it had previously been believed that any stars existed. Further observations revealed more variables and the distances worked out to be just about the same, hence suggesting that M31 was a vast collection of stars outside of what had previously been considered the boundary of the universe.

Within a few years, Hubble and Humason identified a number of the other Messier catalog as being still more “island universes” and they were able to show that the redshift anomalies that had previously been observed were not really anomalies at all but in fact showed how they all related as a group of galaxies.

At that point, the idea of galaxies as universes was essentially dead in the water as they were now obviously part of a larger thing that we now call the universe. Although that identification may get lost at some point in the coming decades as some recent advances in astronomy/cosmology/physics seem to be pointing to what we are now calling the universe to actually be embedded in something yet larger. But I will get back to that at some point.

Sure, if you are going with life on other planets, that seems to be somewhat reasonable. Mind you, I would tend not to expect that the chemistry must be absolutely identical. Functionally identical, for sure. Life without some basis for complex chemistry and an information storage mechanism seems rather improbable.

That being said, If/when we find life, I would assume that it will be associated with the high metallicty population 1 stars, if for no better reason than complex chemistry must have a good assortment of elements to work with. However, the specific abundances of each element will almost certainly vary from one star to another. So that really ought to affect which substances are available in the primordial chemical stew to some degree.

Perhaps different amino acids form due to some significant difference such as a planet having a 20 bar thick atmosphere or whatever. Or if a specific planet has a lower abundance of phosphorus but an abundance of nitrogen, then the basic chemistry will be that much different. If such changes do not prevent life from ever getting started in the first place, then basic evolution should favor whatever solutions work for each specific planet.

Well rob, I think that you might be pushing the analogy a little too far with the idea of a universe in an atom. As far as a conversation starter, it is fine. However, I don't think it is a requirement to get on with this.

Just for grins, what if we model an idea of many universes in some other way? Would the question “why can't they all be different?” still be a valid question to ask? Depending on how one constructs such a model, there may be no reason why that should not be.

As it happens, on the bleeding edge of speculative physics, there are several such models and your question is at the forefront of many of them.

Without getting too technical, let me define the word “universe” as that which follows from the (our) big bang. Then let's postulate that the (our) big bang exists in some larger concept where there may well have been some number of other big bangs.

Each one is unique and the cosmology for each is different.

So now we can consider the basic parameters that ca be used to define individual universes. Let's work with the identified physical constants. What comes to mind are the speed of light, the fine structure constant, the strength of gravitation and several others. About two dozen in total.

It has been well observed that if any single one of those numbers was much different than what obtains for us, then the universe would have been vastly different. So different that as far as anyone can tell, it would not have been possible for stars to have formed or planets to develop. We would not be here to be asking such questions.

OK, I am fine with that. It still does not mean that there is some huge universe making dude who twiddled the knobs on his universe making machine. We can run with the idea that shit happened and we are here. If different shit happened in other big bangs, then they did not result in universes that have beings to ask such questions.

However, that makes much less sense if the number of universes is large. Let's say that there are two universes. One is ours and the other is so different that it has no minds to ask where we came from. OK, I can run with that but it merits a huge “so fucking what?”.

On the other hand, if there are 100,000,000,000,000 universes, then what? Well, in ours, the speed of light is close enough to 300,000km/sec. Would a speed of light that happens to be 300,000.001km/sec. be close enough for minds to exist and ask such questions?