Isn't so called (velocity/gravitational) time dilation, a case of warping the 4th dimension (time); however, unlike space in which case a straight line becomes a curve, with time, a curve becomes a straight line. — Agent Smith

Curvature occurs in spacetime, rather than in 3-D space is my (pathetic) understanding.

so, expansion of space, is the notional 'clock' ticking. The current expansion rate is accelerating — universeness

Is it space itself that expands, or matter within space?

(A year of physics at GaTech in 1956 didn't prepare me for the modern world of physics)

I don't think my question is so profound as to require an exposition on the limits of reality /truth?

Anyway, thanks!

One of the most profound questions which can be asked is 'what is truth?'

Curvature occurs in spacetime, rather than in 3-D space is my (pathetic) understanding — jgill

I'm certain your undertsanding of the subject is far better than mine.

I have a question. Is there a line straighter than straight, that is to say :point: "_____" is actually a curve.

One of the most profound questions which can be asked is 'what is truth? — universeness

My question actually inquires into ground already covered, but indeed, the nature of truth is a profound question. :ok:

Depends who you ask it. For a lot of people the clock is very real and they fight it, save it, buy it, or kill it even. The clock can go awfully slow when waiting. Don't think about the clock! — Raymond

The clock, is what it measures (time) as real as it itself is?

Curvature of space/time/spacetime is described in great detail on sites such as wikipedia. It would take too many words to attempt to describe the details here. Enjoy reading about it if you have the time and interest.

Space expands, objects such as solar systems or galaxies do not expand as they are gravitationally bound. A common analogy is pen marks on the surface of a balloon being blown up. As the balloon expands, the space between the separate marks will increase.
Photons traveling in vacuum are 'stretched' due to the expansion and lose some energy.

Luckily, physicists can have wrong stories. There are different views on the big bang and it depends on your view on big and bang where you place the bìg bang. It is usually placed on the moment matter came into being, after inflation. The real bang is the short moment of inflation. Some people think that inflation is eternal in an infinite universe. And our universe is just a local patch where matter condensed. Without an explanation why inflation. This view is supported by the hypothesis that the universe is flat, which is basically the same position as flat Earthers take. Observations suggest the visible universe is flat but the same holds for Earth and only by looking at the Earth from afar, it is global.Of course we can't look at the universe from afar. But you can give arguments why it is flat only locally. Nobody knows how far the universe extends after the horizon.
General relativity doesn't forbid extra dimensions (string theory even brings in 6, 7, or 26 of them) and it is possible our universe is expanding as a 3d closed structure on a 4d space. At the center of this space was a Planck sized wormhole on which our universe was wriggling tiny weeny as a Planck sized timeless structure. It was wriggling but without a direction in time. There was no cesium back than but you still can put (mentally) a clock there. The timeless state was in fact itself a perfect clock. You can't tell by looking at the state of the universe back then if time goes forward or backward and you can even imagine it has a fluctuating existence with no global direction. So you can put a clock next to it but if this clock goes forwards or backwards, no one can tell. So it becomes pretty meaningless to talk about time at all.
When the two universes of a previous bang on the structure have accelerated away to infinity, the conditions for the next are ideal for a new bang to occur and on both sides of the 4d mouth two 3d structures, a universe and an mirror universe bang into time-like existence.

Now that's a good question! And the answer is no. The clock is only a device we invented and use in relation to irreversible processes. If an irreversible process has proceeded we compare it to the clock and look how many periods it has executed. Tic, 1, tac, 2, tic, 3, ti..., 3.7687987. In nature there are no perfect periodic processes to be found. That's an imaginary only. Even the cesium clock is not perfect.
A clock measures nothing at all. It quantifies irreversible progress by comparing that progress with an imaginary. Of course the progress can be called time.

Yeah, so we just don't know enough yet. Maybe there is a multiverse. Maybe a universe exists in cycles. Maybe the universe has layers of existence. Maybe every quark is a universe. Maybe if we answered all questions then we would wink out of existence as we may have no further reason to exist. My head is starting to hurt again! I think I will go watch a comedy show for a while. Be back soon.

no — Raymond

Possible!

The truth sets free. It's pretty clear to me what happened back then. But maybe that's all happening inside a quark, who knows. Don't we ask questions to know the truth? I think it's no problem to know what happened back then or how nature looks fundamentally. Is that the ultimate goal of science? At a certain point, there is nothing left to ask. Think I kill myself... I'm gonna watch some comedy too! :wink:

When you draw a straight line within euclidean 3D space you are actually drawing a cuboid, you just can't see its width or height, but it's there. So you can't really draw a 1D line, straight or not in 3D space. You can only simulate/approximate it.
If string theory/Mtheory has any truth to it then when you draw a euclidean straight line, you are in an 11D spacetime

Cant kill ourselves because something really cool would happen and we would F****** MISS IT!
A comedy show, a small single malt and then back to the questions!
Not a bad existence really.

:ok:

What the clock measures.

Basic idea = Something that can't be broken down into simpler ideas. Ergo, is undefin(ed/able). — Agent Smith

What the clock measures is change. The measurement of change is time, like the measurement of space is length. Clock is to the ruler as time is to length.

What the clock measures is change. — Harry Hindu

There's more...can you give it another shot?

Thats the definition if time that works for me. Nothing else is needed. Why dont you tell me what I'm missing.

Thats the definition if time that works for me. Nothing else is needed. Why dont you tell me what I'm missing — Harry Hindu

That definition is wanting in many respects. It doesn't, for example, say anything useful i.e. it merely states what's obvious. As for your request to tell you what you'r missing, I regret to inform you that I can't comply, for obvious reasons.

What the clock measures is change. The measurement of change is time, like the measurement of space is length. Clock is to the ruler as time is to length. — Harry Hindu

The clock is not what the ruler is to distance. An odometer would be more appropriate to compare the clock with. The numbers on the clock represent the time passed, the number of times the clock has tic-tac-ed. A An odometer does the same with distance. It's number given corresponds to the amount of distance traveled. The ruler just points to the points in spacetime. This corresponds to the hand of the clock only, or, say to the pendulum swinging below it, or a metronome. So the pairs clock-odometer and pendulum-ruler are appropriate.

Time doesn't measure change. It's a number, represented on the time axis, and by an imaginary clock we put besides an irreversible process. It is itself based on a reversible periodic motion and is as such imaginary. No reversible periodic motion exists in nature (except for the situation around the big bang). So there doesn't even exist a reliable measure for the alleged measuring. How do you measure change by a clock if the change is time? If the clock next to a process indicates that the process has proceeded two hours instead of one hour, is the change twice, what does the clock measure? It indicates a value, (an imaginary value, as the perfect clock doesn't exist), you can put in expressions that describe the evolution of the process, which by itself constitutes time. All processes are irreversible, so the artificial recreation, transformation, of time into a clock is turning time into a non-existent process. Time as represented by the clock is a chimera.
It comes in handy though for describing another more realistic time, i.e, irreversible entropic time and only at the begin state of the universe it had a real existence. It was all that existed, in fact. If we could place that initial state besides a process, we would have the ideal clock. We couldn't say though if that clock was going backwards or forwards.

Pretty far fetched, but hey, it's a philosophy site. Ah! 1 o'clock. Coffee time!

Despite the crude sophistry of the OP, the possibility does seem real that that time is an illusion.

Suppose it was, that every moment was contemporaneous, that the universe evolved from big bang to big crunch in an instant, and we experience every moment of our very brief lives simultaneously.

If this were true, we would still experience the world as we do now. Every moment would have a prior moment, established by memory. Due to the constancy of the laws of the universe, we would still anticipate a succeeding moment. And due to these laws, some processes would evolve at rates relative to others, such as clocks.

All that is required is the laws of the universe, and memory. Time as a real thing seems inessential to explaining what we experience.

Assume R = Time is real — Agent Smith

"Real" is meaningless until it's explained, so the rest is also pointless.

All that is required is the laws of the universe, and memory. Time as a real thing seems inessential to explaining what we experience. — hypericin

There you go. Time as the variable t is an illusion. Light doesn't travel in time, and it's finite speed in space prevents things from happening at once. There only exists irreversible processes (which can be compared with a clock and its values written on an axis, the time axis, sometimes even written as "it", t preceded by the imaginary number i (to symmetrize the metri, already an indication of its imaginary nature. And only at the singularity time is existing as a real clock, which simply doesn't exist in reality. Only in the realm of thought. Time as a coordinate is an illusion. It can be used though to indicate relative progressions of irreversible processes relative to each other in different frames, but labeling processes themselves with clock values (like is done in evolution formulas of a process) is an imaginary excercise.

"Real" is meaningless until it's explained, so the rest is also pointless. — Xtrix

Go scientific!

Go scientific! — Agent Smith

I have no idea what that is supposed to mean.

I have no idea what that is supposed to me. — Xtrix

It's ok. No problemo!

Isn't so called (velocity/gravitational) time dilation, a case of warping the 4th dimension (time); however, unlike space in which case a straight line becomes a curve, with time, a curve becomes a straight line. — Agent Smith

The straight line of time becomes a curved one too. If space is curved, so does time. Curvature can be defined only for the space between two different points. A point has no curvature. If you imagine two different points on the timeline (an imaginary line) and put a clock on each point, then the curvature of time is the difference in timerate of the two clocks. If the two clocks show no difference, time is flat, like space is. All flat lines, quasi Euclidean because of a factor i that is placed in front of t, it. If space is straight, flat, there is no difference between subsequent intervals mdx (corresponding to the rates of the clock on different mdt on the timeline). The m is called the metric on the spacetime. If the metric is constant there is no curvature. Mass curves spacetime, induces a metric (which are the m's arranged in a symmetric 4x4 matrix, which is usually a diagonal matrix with elements on the diagonal only but sometimes contains off diagonal elements giving rise to a torsion of space, like frame dragging), and instead of moving through flat spacetime around mass and under the influence of a force, as happens according to Newton (and even with an instantaneous action...), a mass just follows the curvature, just as in flat spacetime it travels straight.

Yeah, so we just don't know enough yet — universeness

The problem, at the same the true kicker, is knowing it. Once you see it, it all seems so obvious.

Space expands, objects such as solar systems or galaxies do not expand as they are gravitationally bound. A common analogy is pen marks on the surface of a balloon being blown up — universeness

Thanks. It's nit-picking, but space itself has no substance and does not "stretch" as the balloon analogy suggests. The metric changes and objects not influenced by gravity move apart. This is one way of looking at the expansion of the universe. Spacetime is more complex. There's lots of material on curvature in mathematics, but I'm not sure about applications to pure space. Beyond my paygrade.

I have a proof that time is real. I'll show it to you.

I have a proof that time is real. I'll show it to you — Banno

That's unreal!!! :gasp: