Wasting time with philosophical subjects

[fuindordm]

Olber's Paradox

The name of that astronomer was Olber. He postulated that if the universe were infinitely large and infinitely old, then every line of sight from a given point into space would eventually hit the surface of a star, and therefore the night sky would be as bright as the sun.

You could counter that by arguing that a line of sight could end on other things such as planets, space dust or whatnot, but if the universe were infinitely old then such things would have had time to come to thermal equilibrium with all the stars and grow just as brightly.

Olber's paradox was a serious concern up until the expansion of the universe became widely accepted in the late 20's, but it was still something that steady state universe proponents had to contend with in their theories up until the 90's.

Once you give the universe (or at least that phase of the universe where matter has formed hydrogen and other light elements) a finite age, then Olber's paradox is doubly resolved by the appearance of a 'horizon' (the distance that light could have traveled to us from the time the universe became transparent) and by the redshifting of light that has traveled great distances down to the bottom of the electromagnetic spectrum.

So at least in regards to our own universe, we know that it is (in its currently recognizable form, at least) finite in time. We don't know this because of Olber's paradox, but because of three independent observational paths: the relative proportions of light elements in the universe conforms to numerical simulations of nuclear reactions in an expanding and cooling universe; the redshift of spectra from all recognizable objects in the universe is proportional to their distance, confirming a uniform expansion of the universe; and the cosmic microwave background is observed in all directions to have a completely uniform temperature and spectrum down to one part in 10 000, confirming that at one time the universe was a hot plasma in thermal equilibrium with itself.

All this adds up to the Big Bang theory, which starts the universal 'clock' at about 13 billion years ago, at a time when the universe consisted of a hot, dense, plasma of elementary particles.

Note that we don't know whether this ball of plasma was finite or infinite.

We also don't know what happened before that time. Inflation is a good idea, but doesn't add much to the basic picture other than resolving some observational issues that appear to be very puzzling coincidences. (the uniformity of the microwave background over distance much larger than the horizon, the density of the universe being very close to the critical density needed to stop the expansion, etc.)

Heck, we don't even know what most of the matter in the universe is. That question made it into the top ten of the 125 mentioned earlier, I believe.

The universe offers plenty of infinities, for all that: it might well be infinite in extent, and there might well be an infinite number of universes out there; some popular and untestable theories postulate an underlying universe of infinite extent and very high energy, which is just a uniform quantum field of the most fundamental particles... but the uncertainty of quantum mechanics pushes small regions over the threshold of a phase transition from time to time, and these 'bubbles' condense into a recognizable universe such as our own.

The amusing thing is, that since the underlying field is expanding exponentially, and a universe made out of matter expands only as a power law (as time to the 1/2 or 2/3 power, depending on whether matter or energy is dominant), then in the frame of reference of the underlying quantum field all these 'Big Bangs' would look more like little bubbles quickly shrinking out of existence!

However, on Earth, at the current time, the volume of space accessible to us through observation and the number of stars therein is decidedly finite.

Cheers,
Ben

 

[Turanil]

All I have to say is that's it's not the first time that I regret to not having become an astrophysicist instead of a dull illustrator. Ah, maybe in another life...

 

[Umbran]

But it does mean we don't fully understand why an how things don't happen perfectly. If we did, we could calculate it.

We require two different things in order to predict - knowledge of the mechanics, and knowledge of the initial condition. I can describe how and why an object falls (that is mechanics), but predicting the speed of a falling object at a given point in time requires that I know the initial conditions in some form. So, I can know how and why without being able to predict a specific event.

In addition, the Uncertainty Principle tells me that I can only know initial conditions to within a certain precision, limiting the accuracy of predictions.

Plus, what you say only holds for deterministic universes. So far, QM tells us that the specifics of our universe are not deterministic.

In an infinite universe... here, thing about this. We can see 200 units away. Is there stuff in the 201st unit? Maybe, maybe not. We can apply a percentage possibility, though. The 201st might not have anything, but what about the 202nd? Maybe, maybe not. Eventually, there'll be stuff.

The "eventually..." is an assumption. You don't know there'll be stuff. Mabey there will be and maybe there won't. Unless you assume it, theres nothing guaranteeing it. You are free to make the assumption - "In a universe with infinite space, infinite time, and infinite material..." - but don't expect you can go pointing out where I'm making assumptions and expect to avoid beign held to the same standard.

And yet we haven't learned all there is to know about the building blocks and we don't understand how everything behaves, so we can't know this is true. It's possible there's an infinite amount of things to know about the building blocks.

Who said there isn't? The point is, it would be another assumption

This whole time, all I've been trying to say is that infinite space and infinite time are not sufficient to support the conclusion that all imaginable things are possible, and give the reasons why.

I think there are too many assumptions here.

You want a universe where all things imaginable will happen? Then you require more assumptions.

You're limiting yourself to what we've seen.

No, I'm simply starting with what we have seen, for purposes of demonstration.

The theories behind black holes were primarily developed by Hawking. Black holes are an example of where science is shaky.

Ah, but nobody, including Hawking himself, ever called those theories "laws". You were attacking "laws", and brought up Hawking. But Hawking's work isn't law. Thus, it does not apply.

But how can you assume all things Mankind has ever seen isn't local phenomena? Is there a chance that it is local phenomena? If there's a chance it's local phenomena, then in an infinite universe there must be other phenomena we haven't seen.

Logically, no. I would guess that you are conflating chance (physical probability) with chance (estimation of how complete my information is). Either what we have seen is local phenomena, or not. We don't know which, so we assign a probability we are correct - we do so because we are naive, the masurement is meaningless. Only in that sense is there a chance that it is not local phenomena.

However, so long as we assume that reality is objective, then there really is no chance involved. The universe is what it is. The answer has already been determined, one way or the other, and chance doesn't enter into it.

This argument only works because we're talking about an infinite universe. The only assumption I'm working with is the one we agreed to start from.

And I am trying to tell you that the initial assumptions are insufficient. You really require:
Infinite space.
Infinite time.
Infinite material.
And (in effect) that the material be infinitely malleable.

With anything less, we can construct an idea of a thing that won't be allowable in the universe. And, with a little logical tap-dance, we can still imagine things that cannot exist in that infinitely malleable universe.

Was I attacking you? If I did, I didn't mean to. If the original argument is assuming too much, though, then I think we're on very different pages here.

You said, "You may be content in your room, but the universe goes out a bit farther than that." That's addressing the mental state of the speaker, rather than the speaker's argument, commonly called an ad hominem attack or argument. Don't talk about me. Who I am, and what I am content with is irrelevant. My position stands ont the grounds of it's own logic, not upon my mental state.

On top of that, you simply don't have enough information to be making guesses about what I am or am not content with.

 

[Turanil]

I foresee this thread degenerating into a flamewar. Isn't it what philosophy exists for anyway.

 

[Jdvn1]

We require two different things in order to predict - knowledge of the mechanics, and knowledge of the initial condition. I can describe how and why an object falls (that is mechanics), but predicting the speed of a falling object at a given point in time requires that I know the initial conditions in some form. So, I can know how and why without being able to predict a specific event.

The problem is that even if we knew the exact make-up of our own star, we couldn't predict every flaw in the chemical processes that happen. We can find the condition of our DNA, but we can't explain why sometimes it isn't copied perfectly. We can't predict flaws.

In addition, the Uncertainty Principle tells me that I can only know initial conditions to within a certain precision, limiting the accuracy of predictions.

Plus, what you say only holds for deterministic universes. So far, QM tells us that the specifics of our universe are not deterministic.

On the subatomic level, that is true. This bit of the conversation, I understood, was discussing the flaws of science as a whole, not just on the subatomic level.

The "eventually..." is an assumption. You don't know there'll be stuff. Mabey there will be and maybe there won't. Unless you assume it, theres nothing guaranteeing it. You are free to make the assumption - "In a universe with infinite space, infinite time, and infinite material..." - but don't expect you can go pointing out where I'm making assumptions and expect to avoid beign held to the same standard.

It's not an assumption, it's math. Any positive, non-zero number times infinity equals infinity. It's as simple as that.

Who said there isn't? The point is, it would be another assumption

This whole time, all I've been trying to say is that infinite space and infinite time are not sufficient to support the conclusion that all imaginable things are possible, and give the reasons why.

Is it possible there are other building blocks? Yes, it's possible. Therefore, but using the math above, there must be other building blocks in an infinite universe. Not an assumption, but math.

You want a universe where all things imaginable will happen? Then you require more assumptions.

An infinite universe specifically. Doesn't require assumptions.

No, I'm simply starting with what we have seen, for purposes of demonstration.

Then how come you wont' accept the possibility of things we haven't seen?

Ah, but nobody, including Hawking himself, ever called those theories "laws". You were attacking "laws", and brought up Hawking. But Hawking's work isn't law. Thus, it does not apply.

Wel, it's considered solid science, and probably as close to a law as we'll get any time soon. But you do have a point. I'll concede that it doesn't apply.

Logically, no. I would guess that you are conflating chance (physical probability) with chance (estimation of how complete my information is). Either what we have seen is local phenomena, or not. We don't know which, so we assign a probability we are correct - we do so because we are naive, the masurement is meaningless. Only in that sense is there a chance that it is not local phenomena.

However, so long as we assume that reality is objective, then there really is no chance involved. The universe is what it is. The answer has already been determined, one way or the other, and chance doesn't enter into it.

I can see why you think I may have mixed the two 'chances' but I just worded the sentence poorly. Try this:
"But how can you assume all things that have happened in our visible universe isn't local phenomena? Is there a chance that it is local phenomena? If there's a chance it's local phenomena, then in an infinite universe there must be other phenomena we haven't seen."

And the chance is due to the lack of knowledge. It's like the electron probability cloud. Given an energy state, the electron can be anywhere in the cloud. Where it is is objective, but since we don't know for sure, there's a chance for any given point.

And I am trying to tell you that the initial assumptions are insufficient. You really require:
Infinite space.
Infinite time.
Infinite material.
And (in effect) that the material be infinitely malleable.

With anything less, we can construct an idea of a thing that won't be allowable in the universe. And, with a little logical tap-dance, we can still imagine things that cannot exist in that infinitely malleable universe.

All of your requirements are supplied by the initial assumption. The only things that can't exist that those things that break definitions and universal truths, which is always an implied assumption (because without which, the phrasing of the original statement could mean something unrelated to the subject and there's no point in discussing anything at all).

You said, "You may be content in your room, but the universe goes out a bit farther than that." That's addressing the mental state of the speaker, rather than the speaker's argument, commonly called an ad hominem attack or argument. Don't talk about me. Who I am, and what I am content with is irrelevant. My position stands ont the grounds of it's own logic, not upon my mental state.

On top of that, you simply don't have enough information to be making guesses about what I am or am not content with.

You said you were okay with how science worked in your room (At least, that's what I understood your sentence to mean) (Okay: all right: being satisfactory or in satisfactory condition). I didn't mean to address anything further than was already addressed. Again, any attack was unintentional. I apologize.

 

[Jdvn1]

I foresee this thread degenerating into a flamewar. Isn't it what philosophy exists for anyway.

I hope not. This is an interesting conversation, I think.

 

[fuindordm]

I hope not. This is an interesting conversation, I think.

Can other people join in? You two are getting a little hard to follow.

My 2 cents: you both have points.

In our current universe, defined as the extent of everyhing that we can observe, not everything is possible. Even little things like the existence and functioning of stars is highly depended on any number of fundamental constants; tweak these constants, and by extension the laws of the universe, just a little and you end up with stars that can only live a few thousand years, or no stars at all. If the observations we make of the distant universe can be adequately explained by applying the laws that we've determined through experiments in our own backyard, thenwe can state with confidence that the same laws apply in the distant universe.

If you want infinite variety, then you also have to have an infinite variety of physical laws.

This can happen, to some extent, outside our horizon. Physics demands only that the laws of the universe be coherent on a scale equal to the distance that light could have traveled since the beginning of the universe (the horizon length). Observations have shown us that the early universe was coherent on much larger scales, but there remains the possibility that if we reach far enough out, we'll find a boundary between our segment of the universe and another segment where the physical constants are different.

Such things are common in nature. The sheets and filaments that you see in ice cubes are the result of crystallization occuring simultaneously in different parts of the water, but with different orientations. The two crystals grow and spread, but when they run into each other they just stop and you get a surface within the ice that is under some tension, and is not clear like the rest of the ice. Such things are also possible in the substance of space itself, according to Big Bang/inflation theory.

We don't know what's doing the crystallizing in the case of the universe (some fundamental particle/field that hasn't yet been identified in laboratories, thought not for lack of trying or theoretical candidates), so we can't really say what the universe would look like on the other side of the boundary. All the particle masses might be different, or the relative strength of the fundamental forces might be different; or the laws of nature might be even more bizzare.

This is all of course, hightly speculative but still within the realm of what physicists today consider possible. Such 'neighbor universes' might or might not exist.

Then you can try expanding your domain into multiple universes (as I mentioned in my last post), or multiple histories of the same universe coexisting (as some quantum mechanics like to think), or spiritual dimensions to our own universe (which might exist but have not yet been observed with science, which, after all, is only capable of testing repeatable phenomena), and so on.

It's not so easy, after all, to define the universe.

Is it everything that exists, whether we know about it or not?
Is it everything that exists, whether we can affect it or not?
Is it everything that might logically exist, whether it does or not?

Each version will lead you down a different path, which is why you can get into long arguments about the nature of the universe with no issue--each person has a different idea of what they're including in their definition.

Scientists generally restrict themselves to the following:

The universe is everything that has a causal relation to us.

Meaning they include everything they can detect. So far all these ideas for multiple universes are undetectable since they all lie outside the maximum travel distance for light; and since the universe is expanding faster than light, they cannot be reached by us, ever, unless we discover something radically new. But for the present, all these alternative universes are purely speculative. Fun to think about, but speculative.

And if you want to come to agreement about what could possibly exist, you first have to settle on what sort of alternates you've decided to include in your definition of a universe.

Ben

 

[Torm]

commonly called an ad hominem attack or argument.

I love this phrase - it always makes me think of the Manatanaha song from the Muppet Show, for some reason.