Can you describe “a point in time”?

[quantum_wave]

Call it a “now”; a single point in time at a single point in space. How would you describe it?

It seems to me that at a point in time there is no motion so I would think of it as a freeze frame. Things that are happening right up to that point in time would pause in effect.

Is it possible for two points in time to occur at a given point in space if there is no motion between those points in time at that point in space? I guess I’m asking if time passing requires motion.

 

[Ophiolite]

I think it's time to move on.

 

[Acitnoids]

Originally Posted by quantum_wave
I guess I'm asking if time passing requires motion.

The short answer is no. It is motion that requires the passing of time.

Is it possible for two points in time to occur at a given point in space if there is no motion between those points in time at that point in space?

Are you asking if a single point in space can occupy two or more moments in time? If so then no, not from the perspective of that point in space.

Call it a "now", a single point in time at a single point in space. How would you discribe it?

It seems to me that a point in time there is no motion so I would think of it as a freeze frame.

Leave out the bit about motion and you've almost got it. Each moment in time is treated like a single frame. Lets say that each point in space can only record one frame every second. After a minute of recording, each point would have a stack of 60 frames. Now if we could take every stack of 60 and line the frames up with each other we would find that different points recorded a different sequence of events throughout the 60 frames. How much is one frame off from another? Well, that depends on the point from which you chose to compare each stack of 60.

 

[quantum_wave]

The short answer is no. It is motion that requires the passing of time.

Agreed, motion requires the passing of time, but I'm not sure you can say that time doesn't pass if there is no motion? But I complicated the question by bringing up motion. I should have left it at "How would you describe a point in time". You say it is an instantaneous frame? I would agree and if we could freeze time to have things stop NOW across the entire universe then what we would have is a universal "now". Everything would have the same universal time in that one freeze frame.

So I guess I'm expanding my definition of a point in time to include all points in the universe at that point in time, and calling it "now" in universal time.

Leave out the bit about motion and you've almost got it. Each moment in time is treated like a single frame. Lets say that each point in space can only record one frame every second. After a minute of recording, each point would have a stack of 60 frames. Now if we could take every stack of 60 and line the frames up with each other we would find that different points recorded a different sequence of events throughout the 60 frames. How much is one frame off from another? Well, that depends on the point from which you chose to compare each stack of 60.

So by my new definition of a point in time at all physical points, it would be like taking your example and selecting the frame for the exact same time at all points. That would give us the physical picture of one universal "now".

Consider consciousness at a point in time. I don't think consciousness can be identified at a point in time, do you? And thoughts, they don't exist at a point in time either. So consciousness and thought require time to pass and a freeze frame during a thought would have no meaning and reveal nothing about the thought.

 

[Enmos]

Call it a “now”; a single point in time at a single point in space. How would you describe it?

Anyone can describe what's on a photograph.. :shrug:

It seems to me that at a point in time there is no motion so I would think of it as a freeze frame. Things that are happening right up to that point in time would pause in effect.

Is it possible for two points in time to occur at a given point in space if there is no motion between those points in time at that point in space? I guess I’m asking if time passing requires motion.

This is not exactly my area, so I could be saying something utterly stupid, but wouldn't it be described in vectors?

 

[PieAreSquared]

point?.... heck what's a stitch in time?

 

[Acitnoids]

Originally Posted by quantum_wave
So by my new definition of a point in time at all physical points, it would be like taking your example and selecting the frame for the exact same time at all points. That would give us the physical picture of one universal "now.

It does not work like that. If I were to select frame 31 as the moment in time I wanted to freeze then that would only hold true for my point in space. Frame 31 at my point would be frame 3 at another point and frame 42 at yet another. There is no such thing as a single moment for the entire universe.

 

[prometheus]

It's completely possible to have a point in time, just like it's possible to have a point in space. Physicists often talk about taking snapshots where we look at a system at a particular time. One example that I've worked on recently is called a bubble of nothing (Footnote: this may not seem very physical, but it is related to something very physical by holography). It starts at some large size, collapses to a minimum size at t = 0 and then expands again. The instant at t = 0 the bubble is a particular size that you can work out. That's a point in time.

You'll hear people say that quantum mechanics means there is some minimum time interval that you can access via the uncertainty principle. This is true, but not the whole story. Time is a slippery concept in QM because it doesn't have a related operator. AFAIK we don't know how to incorporate the Einsteinian view that space and time are on the same footing in QM yet, and when we do we'll probably have the theory of quantum gravity.

A photograph is not an instant in time, it's an image of the events in a (short) time interval - typically 1/50 - 1/2000 of a second. Not a point in time, but also a pretty small interval by our standards.

 

[noodler]

I read that a point in time has to be inexact, or the "laws of indeterminacy" will be broken.
In other words, a measurement can never be "exact', this would require the universe to "stand still" for a measurement (this doesn't happen, obviously), and the measurement would include the entire history of the universe, in that case.

Heuristically it seems that time has to be "fuzzy" or continuity of measurement would be impossible--the Heiesenberg UP appears to be a requirement of a measurable universe.

 

[Enmos]

A photograph is not an instant in time, it's an image of the events in a (short) time interval - typically 1/50 - 1/2000 of a second. Not a point in time, but also a pretty small interval by our standards.

That's true of course, but I the idea remains the same. Photons strike the sensor at any point in time, so their is a potential image there as well.

 

[quantum_wave]

It does not work like that. If I were to select frame 31 as the moment in time I wanted to freeze then that would only hold true for my point in space. Frame 31 at my point would be frame 3 at another point and frame 42 at yet another. There is no such thing as a single moment for the entire universe.

There must be a reason why you would say that frame 31 would not occur at the same point in time at all points in space. Would you explain your thinking.

I may want to define some circumstances or rules for establishing how we could freeze time universally so that the time is at the same frame for all points in space, say frame 31. If you give me your reasoning why each point is at a different time then can't I define the rules to freeze time all points at the same frame. For example all points are separate from each other and light travels at ... ah ... the speed of light , so if your point is that points are all separated in space, so they are separated in time, then I would make a rule to adjust for the separation. If your point is that each point in space is coupled with a unique time of its own, i.e. literal reference frames for each point, then maybe there is a way to select one reference point and frame and adjust all other points to it so we would have them frozen at the same relative point in time.

 

[noodler]

In order to freeze time at a single point, you will need to freeze time at all the points.
In fact your theory will need to freeze the entire universe, so you can check if all the points are equal in time...

Good luck with that.

I think Einstein was only implying that frames can sychronize with each other, this doesn't mean they have to check they are aligned (synchronized) with an absolute universally "frozen" time. In fact this non-requirement leads to special relativity - whaddaya know...?

 

[quantum_wave]

It's completely possible to have a point in time, just like it's possible to have a point in space. Physicists often talk about taking snapshots where we look at a system at a particular time. One example that I've worked on recently is called a bubble of nothing (Footnote: this may not seem very physical, but it is related to something very physical by holography). It starts at some large size, collapses to a minimum size at t = 0 and then expands again. The instant at t = 0 the bubble is a particular size that you can work out. That's a point in time.

I agree conceptually but I would have to hear more in order to understand why you say you had captured a physical point in time. But regardless, you have the concept of a point in time. Now what about having the same point in time captured for each point in space. A freeze frame of the universe all captured at the same corresponding point in time as I mentioned to Acitnoids? That is the concept of a universal "now" that I am trying to establish. What problems do you see with such a concept?

 

[quantum_wave]

In order to freeze time at a single point, you will need to freeze time at all the points.
In fact your theory will need to freeze the entire universe, so you can check if all the points are equal in time...

Good luck with that.

I think Einstein was only implying that frames can sychronize with each other, this doesn't mean they have to check they are aligned (synchronized) with an absolute universally "frozen" time. In fact this non-requirement leads to special relativity - whaddaya know...?

Let's all just take a photograph of our selves at midnight EST and then make a big collage. That is what I'm trying to conceptualize as a "now" at all points in the universe. Just a concept as a reference point for discussion.

 

[noodler]

At midnight EST? But how do we all make sure that our clocks are properly synchronized?
What if one of our selves takes the photo at 0:00.003 or something?
How will the experiment allow for such systematic kinds of error??

 

[quantum_wave]

At midnight EST? But how do we all make sure that our clocks are properly synchronized?
What if one of our selves takes the photo at 0:00.003 or something?
How will the experiment allow for such systematic kinds of error??

I'm not going to be stuffy about it. If you are that close, whose going to know. But you make a good point when it comes to how we would synchronize all points at the same time. I'm OK with just saying, suppose we freeze time now, and then any point you choose would be at "now". Of course "now" out at the far reaches of the universe and now right here by you or me would be the same point in time conceptually. Then we could talk about our relative locations and the way to figure out how long it would take for light to travel that distance and what would affect that measure of the time-distance between us..

 

[prometheus]

I agree conceptually but I would have to hear more in order to understand why you say you had captured a physical point in time. But regardless, you have the concept of a point in time. Now what about having the same point in time captured for each point in space. A freeze frame of the universe all captured at the same corresponding point in time as I mentioned to Acitnoids? That is the concept of a universal "now" that I am trying to establish. What problems do you see with such a concept?

What you're asking technically is can one define a Cauchy surface for the universe?

EDIT: To define a universal Cauchy surface the spacetime under consideration must be globally hyperbolic. You can look that up on wikipedia for the precise definition, but it's pretty mathsy. Basically, the spacetime has causality and one can go from the Cauchy surface (the "now" surface) to any other point on the manifold with timelike geodesics. Physically it means that the equations of motion and initial conditions on the Cauchy surface uniquely define what happens on the spacetime.

 

[quantum_wave]

What you're asking technically is can one define a Cauchy surface for the universe?

...

Thanks for that link. It does address a point in time from a spacetime perspective, General Relativity; “a Cauchy surface is a plane in space-time which is like an instant of time”. That is very similar to the idea of a universal point in time except for the horizon issue, I’d say. Cauchy surface does sound like the realm of the "mathsy". It is intellectually interesting since it is saying that a point in time has a past and a future. That is where I think we can go with my “universal now” concept.

Everything that we freeze at a point in time has momentum. Go back a step and you have a line. Go back more steps and you have a curve. The curve is one interval of the history of the inertial connection between all objects. A prediction can be made about the future motion of all objects but without the entire history you can’t predict the entire future accurately if we assume gravity travels at the speed of light.

Given the continually increasing reach of gravity, every object is subjected to more history in the next instant. That is because the impact of past events is just arriving; gravity from motion that has occurred in the past.

One issue that separates GR from QWC is the issue of the initial conditions. If there was a history prior to the Big Bang, then that history of motion, inertial connections from distant reaches in the greater universe is continually arriving at all points in space. A geodesic (arena) that is constructed from a point in time 13.7 billion years ago and expands as spacetime to the present does not encompass the entire history that is affecting the motion of objects that exist within the strict confines of the spacetime geodesic. From a QWC perspective there are objects and motion going on outside of the geodesic that also affect the motion of objects inside our arena.

The universal now addresses the difference between GR and QWC in regards to a history of inertial connections that extends past the history that is encompassed within spacetime, given the QWC view of a greater universe and an infinite history. "In general relativity, gravity is not a force but is instead a curved spacetime geometry", while in QWC, gravity is a force that establishes an inertial connection between all mass.

 

[Acitnoids]

Originally Posted by quantum_wave
There must be a reason why you would say that frame 31 would not occur at the same point in time at all points in space. Would you explain your thinking.

Sure, lets say that every point in space can only record one frame every second. The thing is, each point in space is capable of experiencing a different increment for one second relative to another point. This can be observed by comparing a single frame (31) over many points. What hasn't been brought up yet is that each point would have to be plotting a common point(s) in each frame. A stack of 60 frames is only equal to one minute for one particular point in space. The same amount of frames (60) from another point in space may represent half or double the amount of time.

If you give me yout reasoning why each point is at a different time then can't I define the rules to freeze time all points at the same frame.

I wish it were thay easy. Distance is only one varible. You'll have to account for the strength of each points surrounding gravitational fields, each points relative velocity as well as the different pressures and densities. By choosing to freeze frame 31 you would be freezing another point in space at its own independent time frame. From your perspective that point is frozen along with you but from the perspective of the other point, you are frozen at its frame (be it frame 3, 42 or 31).. Of course this is decided by the difference in surrounding gravitational fields, relative velocities, distance between point and the like.

 

[quantum_wave]

Sure, lets say that every point in space can only record one frame every second. The thing is, each point in space is capable of experiencing a different increment for one second relative to another point. This can be observed by comparing a single frame (31) over many points. What hasn't been brought up yet is that each point would have to be plotting a common point(s) in each frame. A stack of 60 frames is only equal to one minute for one particular point in space. The same amount of frames (60) from another point in space may represent half or double the amount of time.
I wish it were thay easy. Distance is only one varible. You'll have to account for the strength of each points surrounding gravitational fields, each points relative velocity as well as the different pressures and densities. By choosing to freeze frame 31 you would be freezing another point in space at its own independent time frame. From your perspective that point is frozen along with you but from the perspective of the other point, you are frozen at its frame (be it frame 3, 42 or 31).. Of course this is decided by the difference in surrounding gravitational fields, relative velocities, distance between point and the like.

Time dilation then? Each point has its own gravitational signature and so there is gravitational time dilation between any two points? Is that your point ?