Expanding Universe, Infinity, and The Philosophy of Science

[Céline Richard]

Hello,

Thank you a lot for this movie.

If you accept questions, i am happy, because i have one
An infinite Universe expands related to what?
Observations and theory show the Universe is expanding. Nevertheless, if the Universe expands, as a balloon, it expands related to what? Indeed, a balloon expands inside a space bigger than it, for instance inside a house, inside a city, inside a country, a planet...

-Maybe i don't understand the concept of expansion.
To my mind, something can expand, if there is a bigger referential, inside which one this thing can expand. Consequently, the condition for the Universe to expand (=to grow), would be the Universe needs a bigger space than itself: a space not reached yet by the Universe, because only the Universe of tomorrow (thus bigger) will be able to reach it. Such an empty space remains for the Universe to be reached, to be got...

-Or (and) maybe, I have a wrong definition of the infinity.
I think the infinite Universe means that the Universe is everywhere. I don't understand how the infinite can expands, because the infinite is already everywhere (no limits, no borders).

Have a very good day!

Céline

[maplebayou1]

I'm with you, I've never really understood how something can be expanding yet there is nothing "outside" of it. The "standard" explanation for this is that the expansion is "intrinsic." This seems to mean that space itself is expanding - that new "locations" are constantly being created. Perhaps one way to try to understand it is to consider the infinity of real numbers between 0 and 1. We can subdivide this interval indefinitely without increasing its length. So while internally, we can count off the numbers 1, 2, 3, and so on, and note that these numbers can represent measurable intervals, an infinity of such numbers can still, paradoxically, sum to the same finite number. When people talk about the "size" of the universe, they don't mean in relation to something larger. We don't know that size. The size referred to an internal measurement of the observable universe or other such constructs.

[Céline Richard]

Hi, thank you for your answer

The "standard" explanation for this is that the expansion is "intrinsic." This seems to mean that space itself is expanding - that new "locations" are constantly being created.

It is beautiful. I have an idea, just an image, an analogy: could we say that the Universe is growing quicker and quicker, like a strange plant?

Perhaps one way to try to understand it is to consider the infinity of real numbers between 0 and 1. We can subdivide this interval indefinitely without increasing its length. So while internally, we can count off the numbers 1, 2, 3, and so on, and note that these numbers can represent measurable intervals, an infinity of such numbers can still, paradoxically, sum to the same finite number.

This is very interesting!
I have the impression we have to watch the interval closer, in order to subdivise it. I mean, the nearer to the interval, the more we are able to subdivise it... Perhaps the interval doesn't grow intrinsically, but we look it closer, until the infinitesimal.
I know we don't keep closer to the Universe, we are inside it... Nevertheless, maybe we keep going closer to some curious regions of the Universe (which look like a 3-dimensional "interval"), where we can observe stars, instead of numbers.

If you have any other image, or idea, i would be happy to see it
Have a very good day, thank you!

Céline

[Céline Richard]

I would like to go on a little further with you idea:

The "standard" explanation for this is that the expansion is "intrinsic." This seems to mean that space itself is expanding - that new "locations" are constantly being created.

It seems the Universe creates new "locations" like cells
I know a beautiful myth: some people have thought the Earth could be a living being, Gaïa. Here, we have an image of the Universe which looks like an organism, which creates itself, as space-time "locations"

[maplebayou1]

The available evidence as well as some theoretical work indicates that the expansion is indeed accelerating and will continue to do so. If this is correct, then over time galaxies and galactic clusters will become ever-more isolated. Eventually the observable universe would consist only of our local group of galaxies. If this is the case, one has to wonder why our universe seems so young ("suspiciously young" as Hubble put it), only about 3 times as old as our little planet.

[Céline Richard]

Hello Maplebayou

I admit i have no good idea

If our Universe is so young (you say it would be only about three time as old as our little planet!! ), yet we suppose that it "was born" one day. Is it Hubble which gave us an idea about the age of the Universe?
If the Universe was born one day, so what was there before it?
I mean, before the Big Bang, was there energy everywhere, which converted into material ? I can't believe the emptyness of energy, of material... I don't understand how nothing could give something. Maybe there was dark energy, or something we don't know currently, which converted into material.

But you asked something else:

one has to wonder why our universe seems so young ("suspiciously young" as Hubble put it), only about 3 times as old as our little planet

Either the Universe is older than we can imagine, either...
What we know, what we see, doesn't concern the Universe, as a whole, but just the "Observable Universe" or something like that, i mean a portion of the Universe. In this last case, the expansion could be local, I mean with "borders". In other regions of the Universe, maybe the Universe could, on the contrary, contracts.

Have a very good day!

Céline

[maplebayou1]

Your thoughts on this matter and mine run pretty much parallel. It's hard for me to imagine that our universe originated at a specific, recent time, yet there was no "time" before that. Time seems like it must have been always there. One way out of this quandary is to suggest that there is a larger "multiverse" of which our universe is only one element.

Hubble discovered the red shift that leads most astronomers to believe that distant objects are moving away from us (or we are moving away from them, depending on your perspective). It is interesting to note that he himself did not believe the "Big Bang" theory. He thought is more likely that the universe was not expanding and there was some other explanation for the red shift. In any case, the very idea of something "before" the "Big Bang" implies time, doesn't it? If there was no time there was no "before."

My intuition, for what it's worth, is that we are looking at the problem the way characters in a story would. In a story begins (with a "Big Bang," in this case), there is a time progression, and it perhaps it ends. In the meantime a character might ask, what was there before? Well, there was no before for that story, for that level of existence. And as far as that goes, there is no actual space, time, matter, energy, or people, not from the point of view of the higher-level "universe" in which that story was created. These things have a virtual existence and to these virtual characters things may seem quite "real." But there is a higher level. Of course this invites a potentially infinite regression of levels, but if that is the case, well, so be it.

[rstevenson]

There is an inherent problem in communicating about the very small, the very fast, the very far and the very old using our common written and spoken languages. These languages were developed here at the bottom of a gravity well where we can see, smell, touch, taste and hear all that is real (or so we once thought.) Our language concepts are fundamentally about real things. Yet our science tells us about these other things, things which are increasingly difficult to describe in real terms.

We have gradually evolved another language which is very good at describing these very strange things; we call that language mathematics. Mathematical analysis of data tells us that the universe as we know it began about 13.75 ± 0.17 billion years ago, and that the concept of "before" has no meaning before that. (You see how hard it is to even describe what the math says.) Math tells us about expansion, and about cosmological red-shift (which isn't at all the same thing as the sort of red-shift produced by local speed differences.) It tells us about the change in the rate of expansion of the universe. It does all these things and many more with extraordinary precision and lack of ambiguity (though the issue is far from settled), which our natural languages cannot do.

Puzzle over these concepts as much as you want to -- it's fun, I do it too. But don't expect to actually settle any of the issues raised using natural language. You'll have to learn how to do the math. That's fun too -- trust me.

Rob

[maplebayou1]

I don't know. I can't help but think of mathematical formulations of QM, which I have some understanding of, versus the various interpretations. The mathematics works just fine, as far as it goes. But what does it mean? What does it really say about issues of ontology and epistemology? What does it imply about causation and its relationship to time? Are these the wrong questions to be asking? Shouldn't science be about understanding as well as prediction? Feynman himself seems to have been very dissatisfied with renormalization in QED, as if it were a kind of "cheat," a way to force the math to work when it really "shouldn't" work. Of course it does work, very well. But what are photons and electrons really up to? Do they even exist? Is every electron a time-reversed positron, and vice versa? Is this all philosophy rather than science?

[Chris Peterson]

I don't know. I can't help but think of mathematical formulations of QM, which I have some understanding of, versus the various interpretations. The mathematics works just fine, as far as it goes. But what does it mean? What does it really say about issues of ontology and epistemology? What does it imply about causation and its relationship to time? Are these the wrong questions to be asking? Shouldn't science be about understanding as well as prediction? Feynman himself seems to have been very dissatisfied with renormalization in QED, as if it were a kind of "cheat," a way to force the math to work when it really "shouldn't" work. Of course it does work, very well. But what are photons and electrons really up to? Do they even exist? Is every electron a time-reversed positron, and vice versa? Is this all philosophy rather than science?

I'm completely with Rob on this one.

IMO, your discussion is a philosophical one, not scientific. It isn't the job of the science, or of the math, so say anything about ontology or epistemology. It isn't the job of science to extend "understanding" of this nature. If we have a theory which can reliably explain our observations, and make accurate predictions, science has done what it is supposed to. If the result is difficult to think about in terms of our everyday experiences (and make no mistake- that is the only problem identified in this discussion), that is an issue with how our brains work, limitations of our thinking processes, or other factors that have nothing at all to do with the scientific theory.

[Céline Richard]

To Rob: Yes, i need more math to understand. I have tried because any human being wants to understand better, it is in our nature, even if we can't. I knew since the beginning I couldn’t understand well the expansion with words, but I hoped to find very little explanations, very basic ones.

To Maplebayou:You have more academic luggage than me: QM is Quantum Mechanics? If it is, I just begin it. I don't know if language can make a few scientific concepts clearer (there are levels/gradations in understanding), but I hope so.
You asked: “what are photons and electrons really up to? Do they even exist? (…) Is this all philosophy rather than science?" Maybe you mean: science=truth, philosophy=fairy tales. I think some philosophers say stupid fairy tales, but the study of the philosophy remains interesting.

To Chris: What is "IMO"? You wrote "your discussion is a philosophical one, not scientific"
I didn't realize my ideas were so out of the subject. I guess i should get away, at least from this part of this forum, in the future.
You also wrote: "It isn't the job of the science, or of the math, so say anything about ontology or epistemology. It isn't the job of science to extend ‘understanding’ of this nature."
Yes; and philosophy will never explain science. However, philosophy matters about the visions of the world, offered by science… because philosophy is the study of ideas, especially the way we see the world. Of course, it is useless for me to think about what I don’t know, if it is out of my reach. I understand:"If we have a theory which can reliably explain our observations, and make accurate predictions, science has done what it is supposed to". As you said, “limitations of our thinking processes”, is why I don’t understand how the infinity can expand. I admit I doubt the infinity can expand, so I doubt about the expansion. I am wrong, although doubt is human.

Céline

[maplebayou1]

Science is obligated to do more than make predictions. It must provide mechanisms. I could say, “I am the reason the sun rises every morning. Tomorrow morning it will rise, and the morning after that it will rise again. I cause this to happen. My predictions are infallible, therefore my claim is correct.” In an “ultimate” sense perhaps science tells us nothing about ontology, because any ontology must be based on untestable assumptions. But within those assumptions I believe that Heisenberg uncertainty and non-locality do say important things about ontology.

I used to think that many ideas were untestable. Whether the universe has a creator (or creators), for example. Yet Sagan suggested a simple and unambiguous test in his novel Contact. An understanding of consciousness has long been considered the realm of philosophy, yet neuroscience seems to be making some significant intrusions. Wheeler’s idea that the basic constituent of nature is information seems like philosophy. A few months ago a paper was published describing an experiment in which information was converted into energy using a Szilard’s engine. Are the laws of physics analogous to a running program on a “cosmic computer,” operating with finite fidelity? This seems like philosophy too. Yet Paul Davies has suggested that quantum computers might provide a test, because to compute the entangled states of a surprisingly small number of particles (<400) requires more information to than the universe might have available to do the job. The unitary evolution of the system would “break down.” Perhaps this is nonsense, I’m no physicist. My point is simply that within the constraints of certain basic assumptions, it seems that science can push into realms often considered to be purely philosophical.

[Chris Peterson]

To Chris: What is "IMO"?

"In my opinion" - an expression most useful when the discussion drifts away from rigid science.

You wrote "your discussion is a philosophical one, not scientific"
I didn't realize my ideas were so out of the subject. I guess i should get away, at least from this part of this forum, in the future.

Not at all. It wasn't a criticism, just an observation.

What we now call science was once called natural philosophy; the boundaries between the two are not always obvious, and where they actually lie is part of the subject known as "philosophy of science".

You also wrote: "It isn't the job of the science, or of the math, so say anything about ontology or epistemology. It isn't the job of science to extend ‘understanding’ of this nature."
Yes; and philosophy will never explain science. However, philosophy matters about the visions of the world, offered by science… because philosophy is the study of ideas, especially the way we see the world.

My view is that philosophy will never teach us anything about how the Universe operates. But it does influence the way in which we seek knowledge of the Universe. And what we learn about our Universe does, in turn, impact our philosophies.

Of course, it is useless for me to think about what I don’t know, if it is out of my reach. I understand:"If we have a theory which can reliably explain our observations, and make accurate predictions, science has done what it is supposed to". As you said, “limitations of our thinking processes”, is why I don’t understand how the infinity can expand. I admit I doubt the infinity can expand, so I doubt about the expansion. I am wrong, although doubt is human.

Our brains are not good at dealing with concepts like "infinity". But the concepts you are struggling with here are well understood (some are, anyway) in terms of solid theory, open to mathematical manipulation. We struggle with concepts like the absence of time, something happening without cause, and other things that are completely described by scientific theory. There is a tendency to believe something must be wrong with a theory that we can't grasp in some intuitive way, but there's no reason to expect the Universe works in a way that should seem natural to us.

[Chris Peterson]

Science is obligated to do more than make predictions. It must provide mechanisms.

My view, as previously stated: If we have a theory which can reliably explain our observations, and make accurate predictions, science has done what it is supposed to.

I would argue that "mechanisms" are something we, given the way our brains have evolved, feel are required to explain things. But I see no evidence that such a thing actually exists. I see no evidence that anything in the Universe necessarily has some underlying mechanism, as opposed to simply being. The concept of "mechanism" seems to me more rooted in philosophy than science.

[Céline Richard]

Not at all. It wasn't a criticism, just an observation.

So i come back to the debate

My view is that philosophy will never teach us anything about how the Universe operates. But it does influence the way in which we seek knowledge of the Universe. And what we learn about our Universe does, in turn, impact our philosophies.

Yes, it reminds me of Etienne Klein, an atomic researcher, and philosophy of sciences teacher, who shares your idea.
I wrote "philosophy matters about science..." but philosophy is a field. I should have written that the way we think, can be influenced by some philosophical currents, some systems of ideas, enough general to influence, IMO , the way we look for scientific truth.

There is a debate:

My view, as previously stated: If we have a theory which can reliably explain our observations, and make accurate predictions, science has done what it is supposed to.

Science is obligated to do more than make predictions. It must provide mechanisms.

IMO , seeking what there is in the Universe appears to be science.
Wondering how facts are related (an interaction) seems to me to be still science… I mean, if I see a northern light, I can think to both the solar wind and the magnetosphere. It sounds good to know how the solar wind interacts with the magnetosphere (ionization, etc), in order to reliably explain our observations. Once we get the interaction, if we ask why, it seems to be philosophical, because we seek a meaning of another nature.

My problem is we could ask: why is there green light in the night sky? Here, we ask for a cause, a reason of being of the aurora in the night sky, but I feel we don’t expect a philosophical answer, because we want a reliable explanation. It is possible there is a quest for a “mechanism” (an interaction) in this question, while I understand, I agree, the Universe is not supposed to seem natural to us at all.

I regret my mail doesn’t concern the topic “expansion” anymore, but it was important for me to give my point of view on a more general topic, because a confrontation of ideas is very interesting

Céline

[rstevenson]

... My problem is we could ask: why is there green light in the night sky? Here, we ask for a cause, a reason of being of the aurora in the night sky, but I feel we don’t expect a philosophical answer, because we want a reliable explanation. ...

And there, I think, is the crux of the matter. When we want a reliable explanation, we ask for a scientific one, not a philosophical one. Philsophy requires no data input and produces nothing provable.

Rob

[maplebayou1]

It's interesting and I think ironic that you would push aside an exercise that requires no "data input" as unprovable, since you started by saying that an understanding of mathematics would move us closer to understanding expansion. Mathematics requires no "data input" either, but surely without it we would have a paltry understanding of nature. Yet the mathematical principles are built on unprovable assumptions. Logic itself is built on unprovable assumptions. In my opinion philosophy helps us to more firmly grasp the implications of our own assumptions, to delineate the boundaries of their consequences. And, like it or not, there is the practical issue that human beings tend to push aside things that they do not believe exist, so our ontologies have a big effect on how we go about the business of science.

To me, the word "explanation" as opposed to "description" has already committed us to an abstract realm of causes and effects, of mechanisms as opposed to merely processes. And it seems to me that science does provide these. I would be the first to acknowledge that it can't ULTIMATELY tell us what exists and what doesn't, because there are unprovable assumptions at the base of any ontology. Godel believed that humans have the ability to intuit things that formal logic cannot provide. Whether he was right or not, I think it is productive and has been productive to pursue such matters.

[rstevenson]

... Mathematics requires no "data input" either, but surely without it we would have a paltry understanding of nature. ...

You lost me there. True, I can write the quadratic equation without requiring any data, but there it sits until I give it values (data) to use in place of a, b and c.

Rob

[maplebayou1]

Well, maybe I misunderstood you. You seemed to be suggesting that philosophy is built on unprovable assumptions therefore it “produces” nothing provable. Mathematics is built on unprovable assumptions and also “produces” nothing provable. My point is that philosophy in combination with empiricism does produce something. It produces explanations as opposed to mere descriptions. Causation is an explanation for observables. A statistical correlation is a description. But science, in combination with philosophy, offers more than that. It says that other things being equal, a correlation between 2 observables means that there is a causal relationship. This provides us with understanding, not just predictive power. Are we deluding ourselves? Who knows? Does cigarette smoking cause lung cancer? Well, that implies a mechanism. It proposes an abstract relationship between observables using natural language, built on untestable basic assumptions. But I think that’s a big part of what science does.

More and more questions that were once thought to be pure philosophy turn out to be testable. I’m not at all sure where the dividing line really is. You might argue that as soon as it moves into the realm of the testable, it ceases being purely philosophy, and I would agree. But it is musing about causation and mechanisms and ontology that often creates the spark to investigate. QM does say something to me about questions that were once deemed purely philosophical. It does more than make predictions, it says something about the nature of the universe. Within limits, of course. Everything is built on basic, untestable assumptions.

[rstevenson]

Yes, you're right, I was suggesting that philosophy produces nothing provable. True, a particular statement by a particular philosopher about one thing may seem compelling. But then you can find a second philosopher who can make a competing statement given the very same input, and a third who can make a third competing statement, and a fourth, and a fifth, ad infinitum and, to my tastes, ad nauseum. It's that lack of a firm ground and (in the mathematical sense) lack of an unambiguous language, that leaves me with such an unflattering opinion of philosophy.

Your suggestion that "Mathematics is built on unprovable assumptions and also “produces” nothing provable" leaves me slack jawed with amazement. I don't even know where to begin to address such a contention.

I think we'll have to agree to disagree.

Rob

[maplebayou1]

Well, perhaps this will clarify it. Which is correct, Euclidean, hyperbolic, or elliptic geometry? Which is correct, classical logic or fuzzy logic? Since mathematics and logic themselves do not provide answers to these questions, they are "unproductive." I think exactly the same is true of philosophy. Without some grounding in empiricism, yes I think it is ultimately unproductive. But with that grounding, it creates understanding rather than just description and prediction. And today's philosophy may turn out to be tomorrow's testable hypothesis.

[Chris Peterson]

My point is that philosophy in combination with empiricism does produce something. It produces explanations as opposed to mere descriptions.

I can't think of an example where this is true. I think it would be closer to the truth to say that philosophy starts by proposing mechanisms, and then attempts to justify them. Outside of trivial examples, however, I can't think of a mechanism provided by philosophical reasoning that has any sort of consensus support.

BTW, scientific processes usually do provide mechanisms- ones that often have consensus support. My earlier comment merely stated my opinion that in order to be scientific, they need not do so. It is not the job of science to describe mechanisms, even though that is generally the result of understanding something well enough that a descriptive theory is predictive.

[Chris Peterson]

Well, perhaps this will clarify it. Which is correct, Euclidean, hyperbolic, or elliptic geometry?

All are "correct", as long as they are used in the correct regime.

Which is correct, classical logic or fuzzy logic?

Both are "correct".

Since mathematics and logic themselves do not provide answers to these questions, they are "unproductive."

Mathematics is nothing more than a tool. It isn't intended to provide answers in the way science is. Like logic (which is, of course, a branch of mathematics) it is useful for connecting A to B, a component of critical thinking. That's all.

And today's philosophy may turn out to be tomorrow's testable hypothesis.

I don't know what that means. Can you suggest an example?

[maplebayou1]

Does information exist, physically? This is an ontological question. Many materialists would answer no. Yet many of these same people would argue that energy does exist, physically. Whether the latter is correct, I think we would have to acknowledge that if one form of energy exists physically, they must all exist physically, because they are interconvertible. Then we are confronted by the fact that information can be converted into thermodynamic energy using a Szilard's engine. This is no longer a philosophical question. It has been tested. If energy exists physically, then information must as well. We have not answered the fundamental question of whether anything exists physically. But we have managed to make an intrusion into a realm that was traditionally considered to be purely philosophical.

[Chris Peterson]

Does information exist, physically? This is an ontological question.

I think it is a physics question, and one that has been answered (in the affirmative) by physics. I guess I'm missing how asking this question from a philosophical viewpoint has been any help.

Sure, there are questions that have been posed by philosophers, and eventually answered by scientists. But those questions would have been answered even if they hadn't been philosophical questions before they were scientific ones. I still can't think of a scientific understanding that depended in any way on an initial philosophical question to construct or suggest a hypothesis.