Why is there no edge to the universe? Time & the possibility of knowledge

[Prodigal_Son]

This thread isn’t particularly Catholic or apologetic, but it is (in my own humble opinion) quite interesting.

When I attended college, I had an astronomy professor who was quite intelligent, but horrible at explaining things. He taught that the universe was spatial, but he repeatedly insisted that the universe has no edge. This made no sense to me, because all physical constructs have boundaries. If the Big Bang happened, then there is always an *edge *to the Big Bang. My professor said no, there isn’t, but he had no good reasons.

Recently, I realized why my professor was right. The key is relativity: space and time are the same thing, the same substance, as it were. When the Big Bang happens is when time begins (so far as we know), and time can only be observed from the present. The universe, in a sense, does have an edge, but that edge is a boundary in time, not a boundary in space.

The universe, at every moment subsequent to the Big Bang, must not be seen as the volume of an expanding sphere, but *only as the surface *of that sphere. Whenever we look into the night sky, we are looking into the sphere, but the events that we see in it took place – of course – thousands of years in the past. There is no edge to the universe, because the universe is as infinite and unbounded as the outside of an orange. (But, of course, the outside of an orange is only infinite in a relative, not in an absolute, sense).

It is worth remembering, always, that whenever we perceive anything with our senses, we are experiencing something that happened in the past. When I hear a train, I hear a noise that exists inside the sphere of time, but I am always on the edge of the sphere (in the present moment). Thus, it is impossible to know anything about the present moment empirically; you can only know what is happening inside your mind (or can you?).

The above reasoning is, I imagine, somewhat uncontroversial. But what impact does it have on how we do science or philosophy? Have we really taken into account the meaning of space and time, or do we operate under the delusion that the two things can be separated? Does it matter that we have no knowledge of the present moment?

 

[Spock]

Very good line of reasoning. Just a few remarks.

First, knowledge is information about some object or event. Since information is carried by physical means, like photons (to allow the perception of the eyes), air vibrations (to make hearing possible), molecules (to enable us to smell something), etc… it prefectly true that we always perceive something that already happened, what is in the past.

The only question I have: “what of it?”. Why do you think this matters?

 

[ckempston]

Infinite in a relative sense? Please elaborate on how something can be relatively infinite.

 

[Prodigal_Son]

Infinite in a relative sense? Please elaborate on how something can be relatively infinite.

Consider the difference between the letter I and the letter O, simply as shapes. “I” stops: Once you have traveled its full distance, you have nowhere else to go. “O” never ends: you can continue going in the same direction, round and round, forever. Thus, the circle is a type of infinity, but no one seriously claims that a circle, or a sphere, contains an infinite amount of space. This is what I mean by “relative infinity.”

 

[Prodigal_Son]

Very good line of reasoning. Just a few remarks.

First, knowledge is information about some object or event. Since information is carried by physical means, like photons (to allow the perception of the eyes), air vibrations (to make hearing possible), molecules (to enable us to smell something), etc… it prefectly true that we always perceive something that already happened, what is in the past.

The only question I have: “what of it?”. Why do you think this matters?

Well, for one thing, I think it brings into question our claim that we live in three dimensions. We always see in two dimensions, although we “know of” a third dimension. But this dimension is *not *(so far as I can tell) depth – it is time. Time is not the fourth dimension, but the third.

Likewise, we can only operate on two dimensions – acting, as it were, on the boundary “line” of the plane of the sphere. And yet we *are *three dimensional, in the sense that our bodies are always inside the sphere – though we cannot, except through the medium of time, get at them.

Is there not a sense that, at the moment of the Big Bang, the universe was one-dimensional? And, if it was one-dimensional, then isn’t it still one-dimensional – is distance an illusion, in other words? (OK, yes, I know this paragraph has become somewhat mystical – but there seem to be scientific realities that affirm ideas of mysticism).

But, of course, the idea that everything is one strikes us as absurd. Does the reason it strikes us as absurd, however, proceed from science? I would say it does not. The oneness of everything is absurd because human consciousness is not one. If the physical universe were one, then we would all experience the same thing (If p, then q). But we do not all experience the same thing (not q). Therefore, the physical universe is not one (not p).

But the premise is flawed. It assumes that “the physical universe is one” is equivalent to saying that “the universe is one”. It assumes physicalism. If you remove the hypothesis of physicalism, then the physical universe may be one, and yet there may be another (mind-based) aspect to the universe.

This is going rather afield from my previous comments about epistemology. But I think that the realization of the interplay of space/time is an extremely fertile field for understanding our lives, and I’m afraid it’s been cultivated very little.

 

[DOShea]

First, the Big Bang is just a theory, a way to explain the phenomena we can observe. It is primarily based on a mathematical model that involves attempting to solve an equation right at the very limit of infinity. This is why BB proponents say things like certain physical laws “began” one second after the BB and so forth. They say this because AT the moment of the BB, their model could not exist IF the physical laws we have today were still in effect. And there are cases where that concept might be sound. For example, how do you have gravitational attraction between two masses if all mass is super-compressed into a tiny dot? But then again, if you DON’T have it, why is all that matter compressed in the first place?

It is a theory full of enigmas that people are still searching for answers to.

When the Hubble and ESA advanced telescopes gave us a view into the more distant parts of the universe we could never see before, we found much more mass (galaxies) out there at distances we never imagined. This required an accounting for it. If those galaxies got there traveling at normal speed, the age of the universe has to increase dramatically. That has the problem of throwing off other calculations already thought to be sound, so another theory was offered that these galaxies traveled faster and then slowed down. Why did they slow down? The only plausible reason is gravity acting as a type of braking mechanism. For that to happen, there has to be some other mass out there to cause it - but we can’t “see” any, thus the name “dark matter.”

For all we know, there could be more matter beyond that, but without knowing that, we are content to deal with what we can see… for now.

Infinity itself is a concept simply meaning no end limit on either end. It does not necessarily have to involve spacial concepts as in the case of an infinite line. If the infinite line has an area, based on it having some “height” as well as length, then that makes your letter “I” infinite as well because one could travel forever around the outside edge of it without stopping. It would make you letter “O” a double infinite, like two parallel race tracks, one inside the other. It is the linear (length) quality that has no end, but not the distance between the racetracks, thus the “area” in between does not have to be infinite unless the letter “O” was infinite in size.

Does any of this matter? My own feelings are that it doesn’t. Consider the closest star to Earth. If we left Earth today in a vehicle capable of making the round trip, traveling at the same speed the Apollo ships traveled to the moon, it would take longer than all of recorded history just to get there. Another equal period just to get back. And that is the closest star outside our solar system. It’s completely outside any individual to live long enough to make a fraction of the journey. So it’s my opinion that dealing in infinites is interesting as an intellectual challenge, but the practical use of it is limited to only the things (particles, light) that can approach infinity in speed. Man cannot, so it is of little use to him.

 

[Prodigal_Son]

First, the Big Bang is just a theory, a way to explain the phenomena we can observe. It is primarily based on a mathematical model that involves attempting to solve an equation right at the very limit of infinity. This is why BB proponents say things like certain physical laws “began” one second after the BB and so forth. They say this because AT the moment of the BB, their model could not exist IF the physical laws we have today were still in effect. And there are cases where that concept might be sound. For example, how do you have gravitational attraction between two masses if all mass is super-compressed into a tiny dot? But then again, if you DON’T have it, why is all that matter compressed in the first place?

It is a theory full of enigmas that people are still searching for answers to.

When the Hubble and ESA advanced telescopes gave us a view into the more distant parts of the universe we could never see before, we found much more mass (galaxies) out there at distances we never imagined. This required an accounting for it. If those galaxies got there traveling at normal speed, the age of the universe has to increase dramatically. That has the problem of throwing off other calculations already thought to be sound, so another theory was offered that these galaxies traveled faster and then slowed down. Why did they slow down? The only plausible reason is gravity acting as a type of braking mechanism. For that to happen, there has to be some other mass out there to cause it - but we can’t “see” any, thus the name “dark matter.”

For all we know, there could be more matter beyond that, but without knowing that, we are content to deal with what we can see… for now.

Infinity itself is a concept simply meaning no end limit on either end. It does not necessarily have to involve spacial concepts as in the case of an infinite line. If the infinite line has an area, based on it having some “height” as well as length, then that makes your letter “I” infinite as well because one could travel forever around the outside edge of it without stopping. It would make you letter “O” a double infinite, like two parallel race tracks, one inside the other. It is the linear (length) quality that has no end, but not the distance between the racetracks, thus the “area” in between does not have to be infinite unless the letter “O” was infinite in size.

Does any of this matter? My own feelings are that it doesn’t. Consider the closest star to Earth. If we left Earth today in a vehicle capable of making the round trip, traveling at the same speed the Apollo ships traveled to the moon, it would take longer than all of recorded history just to get there. Another equal period just to get back. And that is the closest star outside our solar system. It’s completely outside any individual to live long enough to make a fraction of the journey. So it’s my opinion that dealing in infinites is interesting as an intellectual challenge, but the practical use of it is limited to only the things (particles, light) that can approach infinity in speed. Man cannot, so it is of little use to him.

My main point wasn’t about dealing with infinites, but rather of dealing with space. Space is not observable, except in the past tense. To say “I see a hat” is to say “there once was a hat, which may or may not now exist, which is currently being sensed by me”. The people bombed by the Enola Gay saw things intact that had already been obliterated. The only contact we have with the present is in our consciousness – which is physically and temporally distant from even the movement of atoms in our brains.

 

[JimG]

The universe, at every moment subsequent to the Big Bang, must not be seen as the volume of an expanding sphere, but *only as the surface *of that sphere.

Yes, that’s my understanding, but it’s rather old news. That’s the understanding I received from reading a little book by George Gamow, first published in 1947!
(The book title was “One, Two, Three…Infinity.”

The expanding universe is envisaged as an expanding sphere, but the expanding surface of the sphere consists of our normal three dimensions. [Under M-theory, there could be a number of additional spatial dimensions as well.] As the universe expands like a balloon, the little dots on the surface of the sphere–galaxies–become further apart because the 3D space between them is increasing.

I suppose that, in theory, in a spherical universe, one could set off in any direction in a straight line and eventually come back to the starting place, like circumnavigating the globe.

 

[MindOverMatter]

Science is not metaphysics. So when they say there is no edge to space, it does not mean that space is infinite. If that were true then how did it begin to exist? When did it begin to exist? Its senseless, in a the philosophical sense, if space expands with time. Science deals with physics and makes claims only in respect of empirical physics. As i understand, Space/time works together, not separately. Space is infinite only in regards to the fact that it is meaningless to speak of an edge to space. Edges, exist in space, not outside space. But philosophically speaking it does have an edge, as in, it is finite in dimension.

Do you agree with this statement i have just made.

 

[Bluegoat]

My main point wasn’t about dealing with infinites, but rather of dealing with space. Space is not observable, except in the past tense. To say “I see a hat” is to say “there once was a hat, which may or may not now exist, which is currently being sensed by me”. The people bombed by the Enola Gay saw things intact that had already been obliterated. The only contact we have with the present is in our consciousness – which is physically and temporally distant from even the movement of atoms in our brains.

Augustine addresses this question in a way when he talks about memory.

I heard an interesting fellow on the radio recently, who was studying time, and one of the bigwigs in the field. He was thinking that each discrete moment was actually it’s own reality, and still existed. So the me typing the last sentence is still there, typing. There would be kind of an infinite number of universes all existing simultaneously (at least I think there would be an infinite number, since moments don’t have any depth).

It seemed quite compatible with my understanding of theology and metaphysics - in fact., it is rather suggested by it.

 

[Prodigal_Son]

Science is not metaphysics. So when they say there is no edge to space, it does not mean that space is infinite. If that were true then how did it begin to exist? When did it begin to exist? Its senseless, in a the philosophical sense, if space expands with time. Science deals with physics and makes claims only in respect of empirical physics. As i understand, Space/time works together, not separately. Space is infinite only in regards to the fact that it is meaningless to speak of an edge to space. Edges, exist in space, not outside space. But philosophically speaking it does have an edge, as in, it is finite in dimension.

Do you agree with this statement i have just made.

Well, I agree with the propositions that a) space is finite, and b) space does not have an edge. I don’t see why physics and philosophy are talking about different things, however. All truth is philosophical truth and scientific truth. There is no distinction. Now, some things cannot be known by science, but this does not mean that they are not scientifically true.

You say that space and time work together, but I disagree somewhat. Time is an aspect of space. (And perhaps vice versa). Have you considered the sphere analogy in the original post?

 

[JimG]

Science is not metaphysics. So when they say there is no edge to space, it does not mean that space is infinite. If that were true then how did it begin to exist? When did it begin to exist? Its senseless, in a the philosophical sense, if space expands with time. Science deals with physics and makes claims only in respect of empirical physics. As i understand, Space/time works together, not separately. Space is infinite only in regards to the fact that it is meaningless to speak of an edge to space. Edges, exist in space, not outside space. But philosophically speaking it does have an edge, as in, it is finite in dimension.

Do you agree with this statement i have just made.

Disregarding metaphysics for a moment, I think it would be possible in theory to have an infinite space, in the same way that there can be an infinite series of integers or an infinite number of points on a line.

The reason, as I understand it, that the universe has no boundary, is because the space it occupies contains sufficient matter that it is positively curved, i.e. into the shape of a 4D sphere; and spheres by definition have no internal boundary. One can travel the surface of a sphere indefinitely without running into a boundary.

But an empty space, or a space with only a small amount of matter, might in theory extend infinitely in all directions.

That does not mean that an infinite space would be equal to God. Speaking metaphysically, only God can be ontologically infinite–i.e. infinite in his essence. And one of the attributes of God is that he has no extension in space (or time).