# Nature of Time

1. Feb 4, 2009

### Curious6

If time is essentially a property of space in that it measures space's curve, is the reason time is passing on Earth essentially due to the Earth moving as it travels along an ever-increasing space?

2. Feb 4, 2009

### ZapperZ

Staff Emeritus
Er.. one can also easily argue that space is essentially a property of time and reserve what you just said here.

Zz.

3. Feb 4, 2009

### Staff: Mentor

I don't think either statement is right. Both statements are like saying "up is a property of left". Time and each dimension of space are independent dimensions, how can one be a property of the other?

4. Feb 4, 2009

### ZapperZ

Staff Emeritus
It can't. And I'm arguing that if we use the same faulty logic, I could turn it around and use the same thing to argue for another wrong idea.

We know from Relativity that Time and Space are on equal footing. One cannot exist without the other, or else "c" is undefined and meaningless.

Zz.

5. Feb 4, 2009

### Curious6

OK, but isn't space the ontological entity and time just a property of it?

6. Feb 4, 2009

### Fredrik

Staff Emeritus
I think you misunderstood what I said in the other thread. The time measured by a clock is a property of a curve in spacetime, not space. Space is a 3-dimensional slice of 4-dimensional spacetime, which consists of events that all have the same time coordinate. (Different coordinates systems assign coordinates to events in different ways, so there are many different ways to "slice" spacetime into 3-dimensional hypersurfaces that we can think of as "space").

I see now that you brought up this issue in the other thread too:
I don't think I read the whole question before I answered it. I should have made it clear in my reply that we definitely can't think of time as "the extent of space", or as a property of space.

7. Feb 4, 2009

### ZapperZ

Staff Emeritus
Define space as we know it in SR without any use of time.

Zz.

8. Feb 4, 2009

### Curious6

So, what you are basically saying is that in 3-dimensional space all events are necessarily occurring at the same time? It's only when we add the time dimension that events get staggered so that they do not occur simultaneously?

9. Feb 4, 2009

### Fredrik

Staff Emeritus
I wouldn't put it that way. We use a coordinate system to assign coordinates to events. If two events are assigned the same time coordinates, they are said to be simultaneous in that coordinate system. The set of all events that are simultaneous in the coordinate system I'm using, with "right here, right now", is the set of events that I would describe as "space, at this time". But it wouldn't make any sense to say that that set of events is "space, at this time" because if I had used another coordinate system (and I could have), I would have ended up calling a different set of events "space, at this time".

This is why we usually talk about spacetime, and not often about "space". Space isn't something that can be objectively defined. Different coordinate systems disagree about what slice of spacetime is space.

Last edited: Feb 4, 2009
10. Feb 4, 2009

### Staff: Mentor

No. No more than "left" is a property of "up". Space and time are on equal footing.

I would say it in this way: space is simply a particular kind of subset of spacetime.

11. Feb 5, 2009

### ThomasT

I think I sort of agree with this. The nature of time isn't independent of spatial considerations.

I would say that "time is essentially a property of space in that" the nature of space is configurations (positional arrangements) of physical objects, and the nature of time is an indexing of sets of incongruent spatial configurations.

12. Feb 5, 2009

### ThomasT

The spatial configuration of the universe is changing. Space is the positional dimension(s), and time is the indexing dimension.

13. Feb 5, 2009

### arunma

For what it's worth, I have a quantum professor who thinks that time is simply not a dimension at all. When he started covering relativistic quantum mechanics, we spent a day reviewing SR, and he went on a lecture about how time is merely considered to be a dimension as a mathematical convenience. If you think about it he's right: you can't go backwards in time, for example. So if we're talking philosophy here, I have to wonder if it's appropriate to consider time as no different than the three spatial dimensions.

14. Feb 6, 2009

### heldervelez

Events (changes to entities states) are real and they can be timely ordered in succession.

The definition of time and length units are correlated.

quoting http://en.wikipedia.org/wiki/Time" [Broken]
The official SI definition of the second is as follows:...
The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
...
end-quote

where X periods of the radiation have a definite length.

and http://en.wikipedia.org/wiki/Speed_of_light#Speed_of_light_set_by_definition"
quote
The metre is the length of the path traveled by light in vacuum during a time interval of 1/299,792,458 of a second.

Here, the term vacuum is meant in the technical sense of free space. This definition of the metre relies on the definition of the second, which is:[62]

The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.

end-quote

In the same article we can see that 'c' speed is a property of the space.

To make a measuring rod we pick a conventional atom, say Hydrogen or other (Cesium), that enables the measure by comparison of masses, lengths and time interval.

Masses and Lengths are derived from the matterial world. Time is determined by space. Space determines some 'resistance' or impedance to change.

All Mass, Length and also Time units are all relative to the size of matter.

And matter size has been assumed as been constant thru time. But this assumption was never proved and is questionable.

It could be the case that time could have evolved along time. I believe that some researchers in the past have conducted unsuccessful studies trying to pinpoint some time evolution of Time. But they disregarded that M,L,T are all physically tied.

Nevertheless I think of time as a derived entity (a way of speech). It is not absolute, but relative to more fundamental entities (namely Space and Matter).

Last edited by a moderator: May 4, 2017
15. Feb 13, 2009

### petm1

I think that indexing of time the way we do is not the best way to look at time, it is a good way to keep track of events but time is the event itself and its duration thanks to ct. By thinking of what a clock measures in the case of our atomic clock, we are counting the hyperfine transitions “present” in the ground state of the cesium-133 isotope at a rate of 9,192,631,770 changes per second, to make this an ideal thought just think of the transitions as dilating because time does not contract. We count these events of motion, or changes, index them at the rate of 9,192,631,770 to one. If you take two of these clocks set them side by side, turn them on with one switch, they should keep the same count. Pick up one clock and using one second spin it around your body and set it back down next to the other. What changed? For one second one clock was measuring more intrinsic motion than the “stationary” clock, same number of events by both clocks but the clock that moved had a longer duration per event, more time in that clocks present. When you moved this atom it occupied more space per second our count stays the same but its energy, motion, has increased along with the duration of each event net result the clock that moved is behind the other in its count. Granted not by much but you should understand that indexing events does not take into account duration

16. Feb 14, 2009

### heldervelez

Time is not absolute. By Time I mean the Measure we take. Even Life has differents clocks (at different rates).
See a child (5y) compared to me (55y)
One year to the child is 1/3 of his memories. To me is 1/53 of my memories.
and 1/3 > 1/53.
See a bird, total existence 3years and compare to the total existence of a person, 80 years. The number of heart beats is the same. To both 3years and 80 years is a lifetime, and means the same.
When I was a child I need 30 steps to cross the room. Now I need only 10 steps.
And this is relativity.
What is not relative is 'c' that MUST be the same to all observers.

17. Feb 14, 2009

### ThomasT

You say that "our count stays the same". Compared to what? You also note that "the clock that moved is behind the other in its count".

The word, TIME, in the case cited above, refers to an index (the count, the numerical readout of the clock's accumulator) of the atomic transitions.

The word, TIME, in general, refers to indexes of incongruent spatial configurations.

Time indexes all have to do with the association of one set of spatial configurations with another.

The duration of a particular spatial configuration (or set thereof) is defined (measured) by associating the interval defined by it's appearance and disappearance with an index of some set of incongruent spatial configurations that are a subset of the aforementioned interval (usually the count of a 'regular' oscillator, like the one you mention or a vibrating crystal, etc.).

And I agree that there's no absolute measure of the duration of any particular spatial configuration.

There's probably a better way to say what I said. So, if you basically agree with it, or not, take a shot.

Last edited: Feb 14, 2009
18. Feb 15, 2009

### Incyder

Time evolves from a reference frame (a reference frame being a stationary object like a snapshot of you and your loved one). In that initial frame there exits no time (at least in the sense of moving in the forth dimension) only matter superimposed on a field that is directed by the flow of matter only through a series of potentials. You, as an outside observer, might ascribe time to that photo (time, being the motion you might remember or the motion you would like to see it). That's all philosophically speaking (many worlds theory), but that's besides the point. Some theories suggest that the wave function collapse creates gravity, or at least a field to which matter is drawn to.
All of this at this point is rhetoric. It's all a series of math. One reference frame to another. Describing what time is to a mathematician is describing all the wave functions between point A and point B. To me it may mean whether or not you can drive home safe to say goodnight to your girlfriend(after an affair) or bringing home the milk. Knowing what time is to a human is the realization of the data exchanged between between point A and point B. Like "OMG! I hit a f'ing telephone pole" or "Regis, I think I need a life line."

19. Feb 15, 2009

### petm1

In my first post I should not have wrote “is not the best way” and instead put in “is not the only way” to look at time. I agree that what a clock counts as a second is an index of spatial configurations or events, and is one way to think of time, but it is not the only way we measure time. As for your question “compared to what” I was talking about two clocks in one room and how you can change their relative indexes.

I would think that even if there was no absolute measure of the duration of any particular spatial configuration that there is a relative measure in the form of temperature, which imho is another way to measure time.

20. Feb 15, 2009

### ThomasT

How does using temperature measurements not involve the indexing and comparison of spatial configurations?

21. Feb 15, 2009

### petm1

I think our clocks count the events, and temperature is one way to measure the duration of these same events, when you think about these two ways to measure time it almost makes thermal equilibrium and the rule that local clocks tick at the same rate look like the same thought. Then again our clocks do measure the intrinsic motion of the same systems governed by the laws of thermodynamics. All spatial configurations are transitory, they only exist in time, so imho all four dimensions are temporal in nature.

Last edited: Feb 16, 2009
22. Feb 20, 2009

### Kronos5253

Time is nothing more than a human construct. It's a representation of motion, a way to calculate it.

If you talk about time, you MUST talk about motion, and motion is created within space, which is what connects them.

23. Feb 20, 2009

### petm1

I as a human did not construct time; I measure movement with a second which is a human construct. It is such a simple change to make, just think of time as real and space as the optical illusion our mind puts together as Minkowski space making what we feel and what we see via photons fit as one. In my mind’s eye I can take the space out of space/time, but not the time out of space/time and if nothing else both views are equivalent. The way I see it clocks count events (motion) as they happen in the present, with temperature as a measure of the duration (motion) of the events themselves also in the present. The shorter the duration of a single event the more events you can measure in the present, the higher the temperature. This view works if you think time is real.