Thread: An Interesting Thought About Time

Originally Posted by Sageous

Funny you should ask. Space, literally, does not exist.

Then, curiously, it appears you actually have a diametrically opposed position to Nfri.

by definition, space is nothing at all.

By what definition? I've never heard space defined like that. If space is a synonym for the word "nothing", how is it that there are several mutually inconsistent models of space -- flat, spherical, and so on? There's only one type of nothing. How is it that space warps in general relativity? You can't bend "nothing". When I ask my friend "what's colder than absolute zero" and my friend replies "nothing", are they telling me that space is colder than absolute zero? Certainly not. It appears to me that the definition you provide is clearly not correct.

While we're on the subject of definitions, can you give me a few examples of things which you do consider to exist? My tentative guess would be solid objects, atoms, and so on. If so I'm curious as to why these things differ from space in their entitlement to "existing" status. How are you defining "exists"?

Like it or not, there is no such thing as space: it has no mass, no energy, no physical presence at all

It has extension and volume. These can be measured in metres. Energy presupposes the existence of space for its definition, and has a unit of Newton*metre.

Originally Posted by Denziloe

Then, curiously, it appears you actually have a diametrically opposed position to Nfri.

So? I guess I didn't read Nfri's post closely enough, and we certainly didn't plan our respective responses in advance. I'm honestly not sure why that matters, actually.

You're gonna love this:

By what definition? I've never heard space defined like that. If space is a synonym for the word "nothing", how is it that there are several mutually inconsistent models of space -- flat, spherical, and so on? There's only one type of nothing. How is it that space warps in general relativity? You can't bend "nothing". When I ask my friend "what's colder than absolute zero" and my friend replies "nothing", are they telling me that space is colder than absolute zero? Certainly not. It appears to me that the definition you provide is clearly not correct.

As far as I know, there is only one overall definition for space: nothing. Aside from their not being definitions at all, those mutually inconsistent models you list are not about space at all: they are models of the observed (either physically or mathematically) interactions of matter and energy occupying space (yes, you can occupy nothing). It isn't space/time that is warping, but observed light and gravity; it isn't that space is spherical or flat, but that the objects in it have arranged themselves in patterns that cumulatively assume those shapes, with space simply being the measure we use to describe that arrangement. Space remains the same -- nothing -- since you cannot warp, round, or flatten nothing.

Though your interpretation of your friend's response about absolute zero is curious (the context of "nothing" in that case was not about space, but your friend's assertion that absolute zero is the lower limit for temperature, and playing a semantics game with his use of the word doesn't change much), I would agree that the temperature in space that is devoid of any energy or matter would indeed be absolute zero. There may be only one type of "nothing," but that fact does not preclude us from using the word in ways that depart from base meaning of "space." So my definition still feels reasonably correct.

How about a definition from you? You assert that space and time are real things; so what are they, then? Can either be held or measured? And no, volume is not a tangible thing; it is as much a tool for observation as are hours and minutes; that you can establish a measured distance between two objects does not mean that that distance is a tangible, touchable, "thing." Regardless of the volume you measure, the space filling that volume has no mass, no energy, nothing physical at all (except of course for any physical objects that might occupy that volume). So, given that it isn't space that is warping, and that volume has literally nothing in it, how would you define space as a physical entity? Is it energy? Is it matter? Are there space particles, or time waves?

While we're on the subject of definitions, can you give me a few examples of things which you do consider to exist? My tentative guess would be solid objects, atoms, and so on. If so I'm curious as to why these things differ from space in their entitlement to "existing" status. How are you defining "exists"?

I am not defining "exist," but yes, matter and energy certainly exist, because they have definite physical properties. I'm pretty sure I never said matter and energy do not exist. And, since "solid objects, atoms, and so on" are made of matter and energy, they certainly exist. I'm not quite sure how you expected me to answer that question, since I have been implying as much throughout my posts; indeed, if I thought matter and energy did not exist, what I was saying would make no sense at all.

It has extension and volume. These can be measured in metres. Energy presupposes the existence of space for its definition, and has a unit of Newton*metre.

As I already said, volume and length (extension) are tools for measurement, and not physical entities unto themselves. Also, energy certainly does not presuppose space because one of our tools for measuring it is a newton-meter. That is like saying paved asphalt exists only because our tool for measuring it is a kilometer.

I know you're not buying any of this, Denziloe, and that's just fine; my wife and I have been having this argument for a decade now, and she still assures me that time is very much a real thing... I'm quite used to be an outlier on this subject.

Well, this post was a slog which took multiple sittings and doses of caffeine. If it's also a slog to read and respond to, please focus on the final section rather than anything else.

Originally Posted by Sageous

So? I guess I didn't read Nfri's post closely enough, and we certainly didn't plan our respective responses in advance. I'm honestly not sure why that matters, actually.

It wasn't intended as any kind of rigorous point, it's just an interesting reflection on the discussion. You and Nfri were in vehement agreement about the nonexistence of time, but it turns out you have mutually exclusive thoughts on the matter. Such disparate and inconsistent arguments for the same conclusion indicates to me that there's some kind of fundamental confusion about definitions. But again, not a rigorous point worth dwelling upon.

As far as I know, there is only one overall definition for space: nothing.

In that case let me enhance your knowledge: there are two means of definition that come immediately to mind for me.

The first is an ostensive definition, which is the means of definition for all basic observed phenomena; for example, red is defined by pointing to lots of "red" things; "solid" is defined by pointing to lots of solid things, and so on. The human cognitive apparatus is designed to make use of these kinds of definition. Space can be defined by referring to observed examples of space. A cardboard box; there's space in there. The sky; there's space there. Between here and that tree; there's space there. Between the surface of this wall and the selfsame surface? There's no space there. And so on.

The second -- and clearly superior for these purposes, I think -- is an analytical definition; that is to say, the construction of a model. "Space" means a normed vector space. A normed vector space is a formal, symbolic structure with rigorous axioms (you can look them up). There's nothing empty or tautological about this definition; it's a distinct abstract entity with distinct properties and a distinct structure, and humans have the capacity to determine whether a certain abstract structure is observed in reality or not. A sphere can be defined analytically and humans are are able to judge that objects closely approximating spheres exist in reality. The same goes for... an energy potential. Or an electromagnetic field. Conversely, a hypercube can be defined analytically and humans are able to judge that they see no objects that can be reasonably modelled by a hypercube; hypercubes don't exist. In the same way, space, with all of the properties of a normed vector space -- and in particular a three dimensional one -- is observed. And not some other type of thing. That's still a sticking point for me. It is an observed fact that space is modelled by a very particular space. One of its many qualifications, for instance, is that it is three dimensional. A two dimensional space would give different observations; a four dimensional space would give different observations. How can three dimensional space not exist if it has a specific set of empirical consequences which are absent when it is absent? If there's no space then how is it that we observe a specific type of space? You can't qualify nothing. So what has three dimensions? I imagine you'll answer that space doesn't actually exist, but rather that observed matter behaves according to a cosmic conspiracy exactly as if three-dimensional space, and not some other type of space, exists. I have serious reservations about that type of argument, for reasons relating to the central issues that I will cover at the end of this post. But I can't understand how that account even works. For example, forget about action and consider something simpler: a stationary object; specifically, a cube frame, made of wire. How does it make sense to say the matter of this object is "just behaving as if three dimensional space exists, but it doesn't really"? The cube is in three dimensional space; we can see that. It couldn't possibly be there if two or one dimensional space existed; you can't have eight corners connected by non-intersecting lines like that in a one dimensional space. And if it can't do it in one dimensional space then matter certainly can't behave like that when there's no space at all.

Aside from their not being definitions at all

I never claimed to be defining anything; just pointing out that different analytical spaces exist, which is a fact.

those mutually inconsistent models you list are not about space at all: they are models of the observed (either physically or mathematically) interactions of matter and energy occupying space (yes, you can occupy nothing). It isn't space/time that is warping, but observed light and gravity; it isn't that space is spherical or flat, but that the objects in it have arranged themselves in patterns that cumulatively assume those shapes, with space simply being the measure we use to describe that arrangement. Space remains the same -- nothing -- since you cannot warp, round, or flatten nothing.

In that last part you beg the question; I don't think that space is nothing so you won't sway me by pointing out that nothing can't bend. I think that space has a particular structure that matches observations. This is all touching on the fundamental questions about what it means for a model to exist, how they relate to observations, what kinds of things are models, and so on, which I will lay out in a moment. For now I'll just make this point: what about gravitational waves? Gravitational waves are ripples in space. They're not ripples in the objects in space; they're ripples of the spacetime fabric itself, just like light is a ripple in the electromagnetic field, or a wave is a ripple in water. When these ripples reach us, we observe them. Why is it that water waves or electromagnetic waves (presumably?) exist, but gravitational waves are "just" a model which doesn't really exist?

I would agree that the temperature in space that is devoid of any energy or matter would indeed be absolute zero.

I'll give you the benefit of the doubt and say you misread or misremembered my post. But the predicate was not "is absolute zero", it was, "is colder than absolute zero". So this is no means of solution.

...the context of "nothing" in that case was not about space...

There may be only one type of "nothing," but that fact does not preclude us from using the word in ways that depart from base meaning of "space."

You've really stopped making sense to me, here. Not trying to be rude, just stating the fact that I am lost. Can you at least appreciate why these kinds of statement might be incredibly confusing? You said that space was defined as nothing. You've asserted that "space" and "nothing" are synonyms. If this was truly the case then they should be interchangeable. But then you say that they're not interchangeable; that "nothing" doesn't have to be "about space" (in what sense can space be "about" space? And how is it that space is sometimes not about space?) and that we can use "nothing" in ways that depart from "space" (how can the meaning of "nothing" depart from "nothing"?). In my view the only way the above sentences could possibly have made any coherent sense to yourself when you typed them -- even on a purely syntactical level -- is if, subconsciously at least, you don't truly define "space" to be synonymous with "nothing".

I'm pretty sure I never said matter and energy do not exist. I'm not quite sure how you expected me to answer that question, since I have been implying as much throughout my posts; indeed, if I thought matter and energy did not exist, what I was saying would make no sense at all.

This must just be a misreading. I was surmising that you thought they did exist, not that they didn't. Please reread what I said with this in mind to clear up any misconceptions about the point I was making.

Also, energy certainly does not presuppose space because one of our tools for measuring it is a newton-meter.

Please, please don't take this as an insult, because it's hard to state it in a matter-of-fact way that doesn't sound like an insult. But this is simply wrong. Newton-meters measure force, not energy. They can't measure energy. Force and energy are fundamental concepts in physics, and force is about as different from energy as a teacup is different from a tree; you can't help but have serious questions if a person jumbles them up. You could say I'm nitpicking and these details are irrelevant, but you have relied on the terms "energy" and "force" a good few times.

I am not defining "exist," but yes, matter and energy certainly exist, because they have definite physical properties.

Okay, it's time for the nitty gritty stuff. Honestly, I was disheartened that you simply dug your heels in at this point and stated that you wouldn't answer my question, without anything in the way of explanation; it suggested some kind of duplicity and an aspect of rhetoric, rather than mutual, constructive discourse in search of the truth. Especially as I personally consider this to be the nub of the whole thing, and tackling it to be the only way to make progress. I genuinely don't know what you mean when you assert that something exists or does not exist, because you assert existence of some things but not of others when I don't see any special difference between them. It surely follows that we don't know exactly what the other means when they assert something's existence. And progress is surely impossible until this is resolved.

Here's what I can surmise from what you've said. You don't think that something exists simply because it models observations. For instance, you said that the bending of space models our observations of matter and so forth, but you don't think that space actually exists.

But you do think that something exists when it involves energy and mass, because they're "physical properties" (which is left undefined).

I don't understand this because I don't see the distinction; I don't see what makes those "physical properties" special, and distinct from other models. Take energy for instance. Energy is never "observed" in the sense of direct sense perception. Indeed it took a long time for anybody to even notice such a thing was a feature of reality -- the first inklings were around 1700. And what exactly was it that was noticed? A very abstract thing: if you take all of the speeds of a bunch of objects (N.B. e.g. in metres per second), square them, multiply by their masses, halve the result, and then total them, you get a value that does not change, even when the objects collide and change speeds. That's the most basic definition you can give of energy. It is a totally abstract piece of mathematics. It has no "physical" interpretation in terms of a physical object. It isn't "anywhere". It's just an analytical model used to generalise observations and make predictions. It wasn't ever perfect, either; and it didn't work at all for squishy objects, or objects with a lot of friction, and in many other cases. It was (and still is) an approximate model of observations. Here's one interesting point: you don't actually need to do the halving. You could just use the whole squared speeds multiplied by masses instead, and this would give you another quantity (double the previous quantity named "energy") which is just as useful a model. There's no reason to prefer one over the other. So... does the double of energy also exist, as well as energy? That would be rather bizarre. The moon exists. The moon doubled does not exist. And how about other arbitrarily defined quantities? Mass multiplied by velocity cubed, for instance, instead of squared. Does that "exist"? Maybe it's also useful in modelling sometimes. What about any other power of velocity? When does it give you something that "exists"?