Is time an illusion?

[zapshe]

time is not physical, but it is a man made concept that allows us to differentiate between now, later, and before.

Science would argue that if you could "evolve" into a 4D being, you'd travel through time as if it were just like space.

It's theoretical, but there's enough there to say that time is not just a man made concept to explain things and it actually exists.

[helios]

Also, I don't see what it has to do with the quote. If you're in a 3D universe, objects with mass will be 3 dimensional.

Ah, I see what you mean, now. You mean the dimensionality of the universe corresponds to that of its contents.
The "dimensions" of an object are its size, it's measurements.
The "dimensionality" of an object refers to how many dimensions it has.

https://en.wiktionary.org/wiki/dimension#Noun (second meaning)
https://en.wiktionary.org/wiki/dimensionality#Noun (second meaning)

You were arguing my language, saying that I can't say "no longer" since it'll always exist somewhere in time. Was just saying that I mean "no longer" as in "from this point forward". I barely remember what led us down these arguments xD

I think we need to regroup, because we're clearly going down a path of semantical deadlock.

My argument:
* The universe is a 4D manifold (a flat plane, the surface of a sphere, and a Möbius strip are all 2D manifolds; the volume in a cube and the volume in a Klein's bottle are 3D manifolds). "Spacetime", in other words.
* All four dimensions of the universe are independent and interchangeable.
* Objects do not have three dimensions, they have four.
* Objects do not move in time nor space. Motion as humans perceive it is "illusory", so to speak. We are merely perceiving slices of the object's worldline.
* Gravity is the bending of a specific region of spacetime. It doesn't happen specifically in time nor in space, but in all four dimensions.

I think up to here, all five points above are supported by relativity and cosmology, but I'm willing to accept citations to the contrary.

Your argument is that time is "inside" space. I ask you explain which, if any, of the points that idea contradicts and how, and how you'd amend those points to reconcile them with your argument?

[N8MNAqkS]

I am speaking more in the realm of common sense, not pseudo science.

science could argue any number of things, but they would all be theoretical.

common sense is not theoretical.


also if you want I scientific answer for it:


days go by not because of time, but because the earth moves around the sun and spins as it does so. also "time" changes is relative to your current gravity and position. we even have "time zones" because the time in one part of the earth is different then in another part of the earth, relative to where you are.

when I say that time is a man made concept, I mean we, as human, define what time is. we define a minute as 60 seconds, we define an hour as 60 minutes, we define a day as 24 hours, a year as 365 days. and before we all agreed on this system, not every culture had the same calendar. time is defined by man.

[zapshe]

You lost me after the first point.

* All four dimensions of the universe are independent and interchangeable.

Interchangeable and independent? If we look at my example of taking any dimension from a 3D object, it'll collapse into a 2D one with length and height, even if length or height was the dimension removed. So in a way, yes interchangeable. But not independent. Without the previous dimension, you can't have the next one. You can't have width without BOTH length and height. Otherwise, you'll have a 2D object with length and height (the "width" aspect will become one of the two).

* Objects do not have three dimensions, they have four.

In spacetime they have 4. In mere space, they have 3. Agreement? And to exist in time, you have to exist in space, the two are not mutually exclusive. And to exist in space in this universe, you need to have 3 dimensions.

* Objects do not move in time nor space. Motion as humans perceive it is "illusory", so to speak. We are merely perceiving slices of the object's worldline.

Perceiving slices of the object's worldline? Without moving time, how would you establish an object's worldline? You exist in space and move through time. If you're not doing both, what would the worldline for you be??

* Gravity is the bending of a specific region of spacetime. It doesn't happen specifically in time nor in space, but in all four dimensions.

Perhaps it doesn't happen in one in specifically, but it's the mass which is causing it. And again, the mass exists within space over the span of time. And I say that mass exists in this way because you need to exist within space before you can move through time. Again, without height and length, you can't have width. So without all 3 of those, you can't build up to having time, at least not for any object with mass.

Your argument is that time is "inside" space. I ask you explain which, if any, of the points that idea contradicts and how, and how you'd amend those points to reconcile them with your argument?

Simple, the universe is made up of space and time joined together. And my argument establishes that space is needed for time, otherwise, where would time exist? And for mass to go through time, it needs to exist as a 3D object in space first. All dimensions are interchangeable, but build on each other - so not independent.


If you argue all 4 dimensions are independent, then you argue that space and time are independent (3D space, 1D time). But time cannot exist without space.

Also, we could wonder why gravity affects time. To me, it would seem that the mass exists in 3 dimensional space, is curving that space, and affecting time which also occupies that space.

At the very least, I'd say that saying time exists within space wouldn't contradict any theories or discoveries thus far. The universe a vast space in which time flows. My view that follows is that without space, no place for time to exist. No time, and nothing can happen within that space, but the existence of space itself wouldn't depend on time. If you could look at the universe from the outside with an unaffected prospective, would the universe disappear if time ceased to be or stopped within it? Or did the universe simply stop doing anything since there's no flow of time for things to happen?

I can't really cite anything since none of this can be proven. However, I haven't seen it written anywhere that all dimensions are independent.

[helios]

If we look at my example of taking any dimension from a 3D object, it'll collapse into a 2D one with length and height, even if length or height was the dimension removed.

I don't understand what this means. A 2D dimensional object has two dimensions. You can choose to call them "width" and "height", or "length" and "depth" or whatever, but the name is not an intrinsic property of the dimension.

But not independent.

See https://en.wikipedia.org/wiki/Linear_independence

In spacetime they have 4. In mere space, they have 3.

Take a solid cube and intersect it with a plane. The result is a 2D shape, right? But that's only the slice you took, the cube is still 3D.
Likewise, when you perceive an object, you're taking a 3D slice of it, because you can only perceive the present. The totality of the object is still in 4D spacetime.

Without moving time

Again, time and space do not move. They're dimensions.

how would you establish an object's worldline? You exist in space and move through time. If you're not doing both, what would the worldline for you be??

We don't move through time, we exist in spacetime. Our perception of the present moves through time.

And again, the mass exists within space over the span of time.

This is equivalent to saying that it exists in spacetime (or in a specific region of spacetime). You're already agreeing with me.

And I say that mass exists in this way because you need to exist within space before you can move through time.

No. You can't do one without doing the other in this universe. Either you exist in the universe and in all four dimensions, or not at all.
Let's imagine the briefest form of existence possible; let's say that there's a particle called the "ephemeron" that has no size and exists only for an instant of zero length. Literally the only thing we can say about the ephemeron is when and where it existed.
Now, you say you have to exist in space before you can exist in time. If the ephemeron doesn't exist in time (we can't say when it existed), does it exist? If it doesn't exist in space (we can't say where it existed), does it exist?

the universe is made up of space and time joined together.

"Joined" how?

If you argue all 4 dimensions are independent, then you argue that space and time are independent (3D space, 1D time).

That's not what "independent" means (at least not in the way I was using it). See the link to linear independence.

But time cannot exist without space.

I agree with this, but further state that space cannot exist without time. Space and time are parts of spacetime, the Universe. A manifold without space or without time is not the Universe but a universe, and since space and time are dimensions of the Universe, a universe that lacked one could not be said to have the other, strictly speaking.

Also, we could wonder why gravity affects time. To me, it would seem that the mass exists in 3 dimensional space, is curving that space, and affecting time which also occupies that space.

Remember the canvas analogy; I specifically chose canvas instead of paper because it bends easily. If you pinch the canvas and stretch it, it deforms in the vertical and the horizontal directions. We wouldn't say that "verticality" exists inside "horizontality", or vice versa.
Gravity likewise deforms spacetime.
https://en.wikipedia.org/wiki/Gravity#General_relativity
Can you give a single citation that says anything like "time exists inside space"?
<EDIT>
Incidentally, that spacetime bends in this manner is where the phrase "the fabric of spacetime" comes from.
</EDIT>

I can't really cite anything since none of this can be proven.

Nonsense. General relativity basically requires spacetime to be a four-dimensional manifold, and it's been as heavily field tested as any scientific theory can be.
At least try to back up what you're saying, and recognize that if you can't find anything that supports your point of view, maybe you need to reassess your assumptions.

[367kGNh0]

"Joined" how?

Proportionally.

[zapshe]

Nonsense. General relativity basically requires spacetime to be a four-dimensional manifold, and it's been as heavily field tested as any scientific theory can be.

All that spacetime says is that space and time are tangled together. You can't view them separately. I meant my own statements.

Can you give a single citation that says anything like "time exists inside space"?

If you look at the universe, it's made up of space. Go back to my analogy of looking at the universe as a god unaffected, would the universe suddenly disappear if time stopped existing? Certainly that would happen if space disappeared, but time?

further state that space cannot exist without time

Why would space be dependent on time?

"Joined" how?

Tangled in spacetime.

This is equivalent to saying that it exists in spacetime (or in a specific region of spacetime). You're already agreeing with me.

Yes, I am agreeing with you. If it exists in space and moves through time, it's in spacetime.

Again, time and space do not move. They're dimensions.

More specifically then, we move through space and time.

You can choose to call them "width" and "height", or "length" and "depth" or whatever, but the name is not an intrinsic property of the dimension.

It's only a naming thing because we know that they are interchangeable. If you took a cube and needed it to be 2D, you'd remove width. In reality, you can remove any of the 3 dimensions, but width is what we would associate. For example, take away height from a cube, and it becomes a 2d square, with height and length. This is because width depends on there being the other 2 dimensions before it. Interchangeable, but they build ontop of eachother. Now go a step further into 4 dimensions, and notice that you by default need your previous 3 which exist in space.

Anyway, the argument isn't for matter. Matter wouldn't exist in space if it doesn't exist in time. The argument is for space itself. Would space stop existing if there's no time? The use of matter in the argument is to see that you need a 3d object in space to exist in time. If you had a 2d object, it wouldn't be able to exist in this universe let alone move through the same time. Once it can be in space, it'll be in spacetime.

Anyway, why would time not exist without space? And why would space not exist without time? In my mind, space can exist happily without time, simply nothing will ever happen within that space. Why would space be dependent on time?

EDIT: I'm obviously not an expert and I could be wrong. But I simply haven't been convinced and find my own reasoning to make sense.

[helios]

All that spacetime says is that space and time are tangled together.

"Tangled" has no mathematical meaning. The width and height of a square are not "tangled" together, they're measurements of the square.

god unaffected, would the universe suddenly disappear if time stopped existing? Certainly that would happen if space disappeared, but time?

The universe? Yes. There's still something there, but it's not the universe anymore. If from a tesseract you remove one dimension (it doesn't matter which) you get a cube. If you remove three dimensions (again, it doesn't matter which) you get a segment. Neither a cube nor a segment are a tesseract, they're entirely different kinds of objects.

If you took a cube and needed it to be 2D, you'd remove width. In reality, you can remove any of the 3 dimensions, but width is what we would associate.

I honestly have no idea what you're talking about. To be frank, the first dimension I think about removing is depth, because that's the one I can't draw on a flat surface.

For example, take away height from a cube, and it becomes a 2d square, with height and length. This is because width depends on there being the other 2 dimensions before it.

I am absolutely baffled. What are you saying?? I don't understand!

Now go a step further into 4 dimensions, and notice that you by default need your previous 3 which exist in space.

Yeah, but I can pile those dimensions up any way I choose. You seem to assume that the fourth dimension will always be time, but that's not the case.
1. Time. A universe with only time has dimensionless "degenerate space". It's present is a single point with no size that can either contain an elementary particle or not. The particle blinks in and out of existence seemingly spontaneously.
2. Height. Now the present is a finite segment, now that space has one dimension, the particles in the universe can move up and down, but that's all.
3. Width. Now the universe looks like a TV screen. Things can move up and down and side to size, and 2D shapes can exist.
4. Depth. This is our universe.

Now, you might say "aha! You had to put that 'degenerate space' in there for the 1D universe with only time!" Well, if you had a 3D universe with no time, you would also have degenerate time of zero length. A dimension is just a way to measure something, and you can measure something that has zero length. Our 4D universe has zero length in infinitely many dimensions.

[zapshe]

To be frank, the first dimension I think about removing is depth,

My bad, that's the word I meant.

I am absolutely baffled. What are you saying?? I don't understand!

Lets use depth this time. You can't have depth (3 dimensions) without the previous two. You already argue my point by saying later that I assume the 4th dimension will always be time.

Now, you might say "aha! You had to put that 'degenerate space' in there for the 1D universe with only time!"

Lol, I did think that for a second!

You seem to assume that the fourth dimension will always be time, but that's not the case.

Perhaps mathematically this works fine. However, in this universe, for an object to exist in space it must already have 3 dimensions. So either time comes "before" space or "after". Either an object will gain a dimension in time before space (which means it's not even an object that can exist in this universe at that point!), or an object gains dimensions in space then move through time. So in this case, the 4th dimension will almost certainly have to be time.

[helios]

However, in this universe, for an object to exist in space it must already have 3 dimensions.

So first you try to argue that time depends on space because you can remove time from the universe and still have a universe, and now you try to argue that objects in our universe needs such-and-such?

So either time comes "before" space or "after".

Neither. For an object to exist in our universe it must have four coordinates. It must exist somewhere at some time. If it doesn't have either it doesn't exist.

[zapshe]

now you try to argue that objects in our universe needs such-and-such?

Well, this one concerns matter more and is subject to the chicken and egg dilemma. If you exist in space then you therefore must exist in time, but if you exist in time you must also exist in space. And I say in our universe because that's the only one we know to exist. Mathematically, you can do a lot of things that are not reflective of the real world, so you have to add practicality by looking at the universe.

But the original argument is still, as you said, you can remove time and still have space. You told me space would disappear, so I asked why space would be dependent on time for existence. You also said something would be there if time were taken away, but it wouldn't be the universe.

Neither. For an object to exist in our universe it must have four coordinates.

Yes, this is true. It must exist within space and somewhere in time. Again, it was more of a chicken and egg thing so I suppose it wouldn't help the case.

Anyway, in my mind at least, space is the vastness of the universe, it is the universe. Take away time, you have a universe with only space where nothing can happen. But take away space, now there's not even a universe there! So it comes to reason that within space there is the flow of time, where time exists.

[helios]

But take away space, now there's not even a universe there!

But there is. It's just a universe with 0D space. Just because you don't have a spatial position doesn't mean nothing exists.

[deleted account xyzzy]

It's just a universe with 0D space.

Before the Big Bang, or after the Great Crunch.

[zapshe]

But there is. It's just a universe with 0D space. Just because you don't have a spatial position doesn't mean nothing exists.

We agreed that without space there's no time? At least not the time we know of in this universe.

Either way, I don't think the argument will go anywhere. There's no way to see if a 0D universe would actually be possible - let alone have a time flow. And I suppose my arguments are just as untestable.

Before the Big Bang, or after the Great Crunch.

Can't know for certain what was there before the universe.

[helios]

If you accept that a universe with no time would be like a sculpture, with space but no progression, then you have to accept that a universe with no space would have progression but no space. It's exactly the same thing.
In a 3+0D universe you can describe the position of a particle using 3 numbers, (x, y, z), which identify its location in space (i.e. where it exists).
In a 0+1D universe you can describe the position using just one number, t, which identifies its location in time (i.e. when it exists).
In our universe we need four numbers (x, y, z, t), the location in spacetime (where and when).
This is what it means for a universe to have dimensions; it's how many numbers you need to specify locations. Are there any contradictions here? If there aren't then you have to accept that time and space are orthogonal. Yes, in our universe they're inseparable because that's the way our universe works, we but can conceive, without falling into any logical contradictions, of universes with only space or with only time. You already accept the former, I'm trying to get you to understand that the latter is equally valid.

[salem c]

There's an awful lot of "it" being wasted on this thread.
Are you still sure it's an illusion?

Time is how the universe stops everything happening at once.

[helios]

Eh, you know. You gotta pass the time before the grave somehow.

[z05DSL3A]

Time flies like an arrow; fruit flies like a banana

[zapshe]

You already accept the former, I'm trying to get you to understand that the latter is equally valid.

I accept how a 0+1D universe would operate. But really, you can only be certain of how things work in this universe where time and space are inseparable as you've said.

So I suppose you're right theoretically, but then questions pop up. Why in our universe are time and space inseparable? Lets say you were somehow able to separate a piece of spacetime from the rest of the universe, lets say a small cube. If you get rid of space, now there's nothing, no space or time - agreeable? If you get rid of time, now nothing in that space can progress (and any matter inside of it may theoretically disappear). If you tried to shine light through that space, no light would come out the other side since light can't move through it, no time is passing inside that space.

Though, again, I admit I could be wrong, there's certainly no way to test anything I'm saying.

Eh, you know. You gotta pass the time before the grave somehow.

When you're trying to study for Calc 2, suddenly everything else in the world seems more interesting.

[helios]

Why in our universe are time and space inseparable?

Because our universe is made of both. If you don't have one it's no longer our universe, but a universe.

Lets say you were somehow able to separate a piece of spacetime from the rest of the universe

In a way, this already happens. If you look to one end of the observable universe, to the farthest primordial star you can see, and then look to another equally distant star in the opposite direction, the observable universes of those two stars intersect with your own, but not with each other. For all intents and purposes, those stars are topologically disconnected from each other; there are no geodesics from one to the other.

If you get rid of space, now there's nothing, no space or time - agreeable?

No. The entire point of my previous post was explaining why that's not the case. Why if you start with spacetime and take out the space you're left with nothing? How does that make any sense? Where did the other dimension go?

If you get rid of time, now nothing in that space can progress (and any matter inside of it may theoretically disappear)

So if you take space from spacetime you're left with nothing, but if you take out time you're left with space? You're applying a double standard, you're treating space differently from time without giving any explanation for why this is acceptable.

Again, this is like saying that if you flatten a cube in this direction it turns into a square, but if you flatten it in that direction, the cube ceases to exist completely and utterly. It doesn't turn into a segment or even a point, just thinking about what the cube turned into leads to a contradiction.