Time: What Is It & How to Use It Wisely

[lakshmi]

what is time

 

[rayjohn01]

Time is what you read on a clock.

 

[Prometheus]

Time is what you read on a clock.

This is a pretty shallow definition.

 

[Prometheus]

what is time

Time is that part of the universe that is infinite.

Post Big Bang, time is that part of the universe that is bound up with space such that space can go in motion.

Space can only be still, except for time, as space goes in motion through time.

 

[rayjohn01]

to Prom

You mean the body clock , atomic clock etc are simple ?

 

[Prometheus]

You mean the body clock , atomic clock etc are simple ?

Not at all. Nor did I say that these are simple.

What I said, and what I contend, is that to consider time only in the context of what a clock measures is a pretty shallow concept of time.

While all bears are animals, it does not follow that all animals are bears.

While all clocks measure time, it does not follow that all time is what clocks measure.

 

[rayjohn01]

I believe we have no knowledge of time but through clocks -- but they come in a variety of form , a clock is something which changes with time , it is the change we recognize -- maybe your just restricting your definition.

 

[mani]

The more fundamental the concept the more difficult it is even to explain.
The concept is associated with "change". Time can be considered as that quantity against which we "measure" change.

 

[Prometheus]

-- maybe your just restricting your definition.

How nice. That is the same thing that I just said about you.

I believe we have no knowledge of time but through clocks -- but they come in a variety of form , a clock is something which changes with time , it is the change we recognize

Your belief is valid. However, I suggest that you investigate the theory of relativity. This will provide you with a greater context for time.

Are you suggesting that time only exists as a man-made construct, such that we can only identify it through the use of clocks. When relativity speaks of space-time, do you believe that the time part of space time is no more than what a clock measures?

I am sorry. Of course, that is what you have been saying. I recommend that you lessen the restriction on your definition. You will find that time now has much more meaning that your limited concept.

 

[Prometheus]

Time can be considered as that quantity against which we "measure" change.

I will not argue with this statement, except to suggest that it is somewhat limiting.

Are you suggesting that time only exists as a function of our ability to use it for measuring purposes?

 

[HungryChemist]

Question is...

Time is that part of the universe that is infinite.

Post Big Bang, time is that part of the universe that is bound up with space such that space can go in motion.

Space can only be still, except for time, as space goes in motion through time.

Question was...What is Time?

Time is that part of the universe? What is it mean to be part of the universe? What isn't part of the universe? hmm...

Space can go in motion?? Space can go in motion relative to what?? or What is space?? What is it mean to be bounded?

Well, I must agree not with this type of verbal poetic argument of time. I prefer the previous post saying that time is what you read on the clock. At least it gives you the way to "measure" time.

 

[lvlastermind]

what is time

Time is a tool(like a ruler) used to measure something intangible. Infinitely divisible in itself unless looked at by quantium mechanics. Time has significant relationship to motion which is not quite understood. One cannot measure time without motion.

 

[yesicanread]

I heard that time moves the solid 3 dimensions/cube.

 

[ryokan]

what is time

From a physical, biological or psychic viewpoint?

Time is associated to Universe expansion, increase in entropy and aging.

 

[pnaj]

As someone said earlier ... the more fundamental the concept, the more difficult to explain.

A similarly difficult question is 'What is space?'. Particularly, 'what is one dimension of space?'

I think that you have to use the 'restricted' language of mathematics to attempt to describe time, space etc. in such a way that the description can be tested by experimenters.

All else is philosophy.

 

[pnaj]

I've just noticed this thread ... https://www.physicsforums.com/showthread.php?t=37587

pnaj.

 

[pervect]

This is a pretty shallow definition.

It's a very good definition, if one is interested in science. While you don't absolutely HAVE to measure something to make predictions about it, it's usually very difficult to get very far without doing measurements. Talk about time that doesn't involve actual measuments tends to drift off into philosophy, unfortunately, rather than science. The problem with this is that philosophical issues can be debated endlessly, and tend to become disconnected from the physical world. So, all in all, "time is what you measure with a clock" is a great definition for science. IMO, anway.

 

[rayjohn01]

Relativity

One of the endless debates which goes on is the meaning of time in this context. Some people would like to replace the clock with a concept of 'absolute time' and 'absolute space' because measurements seem to indicate weird things are at work such as 'dilation and 'contraction' and in the 4 space of STR we must look at 'the interval' as the 'distance' between events.
But you will notice that try as they might they still refer to clocks even if it's 'dimension' is orthogonal to 3 space.
The definition is not restrictive , indeed the bears mentioned are excellent reminders of the 'hibernation clock' and those who would like to avoid the physical there is the 'mental clock' , so I stick by my definition and for those who find it 'shallow' then your welcome to swim in deeper waters.
Ray.

 

[Prometheus]

"time is what you measure with a clock" is a great definition for science.

Personally, I would not agree that any definition that contains the pronoun you could possibly qualify as a great definition, but that is just me.

Time is what interacts with space to form space-time, the fundamental building block of the universe. I consider that any definition of time that ignore space completely, and that ignores the impact on space of time, is quite shallow. To instead contend that time is no more than what a clock measures minimizes most of the value of understanding time, in my opinion. I accept this definition as having value from a social point of view, so that we can know when to celebrate each other's birthday and such, but not from the view of modern science. The frame of reference of a clock is basically completely irrelevant, in my opinion, to the main value of understanding how the space of an object in space-time interacts with its time.

Please feel free to use whatever definition you wish. There is certainly no requirement that we agree. Feel free to consider this to be a complete definition if you wish. I do not, however.

 

[Prometheus]

Some people would like to replace the clock with a concept of 'absolute time'

Do you consider that a clock provides us with absolute time?

On the basis of your definitoin, I get the impression that you do.

 

[rayjohn01]

Prom

Sorry but I am not going to be draw into a debate -- why do you not simply answer the original question -- I've given my opinion . Ray

 

[wuliheron]

Time is life itself, no matter how you look at it.

 

[Gerinski]

2 threads came in a very short time with the same subject, I just copy below what I already wrote in the thread "time" posted by Neo.

I believe this question belongs more to the Special & General Relativity forums, you will find some interesting discusions about it there.

In any case, indeed it seems that the passage of time is just a perception due to the perspective we see the universe from.
Time is relativistic so it's a kind of perspective which unfolds more or less depending on our velocity relative to the other material things in the universe.

It's like when you watch from the front at 2 cars driving behind each other, you see them at the same place (at least if you look with only one open eye to neglect the stroboscopic effect for depht perception), yet if you move sideways you can perceive that there is some distance between them.

This strongly suggests that what we call past and future "already exist" if we consider the issue free from the limitations of our perception abilities (since the time interval we may measure between 2 events is just depending on the perspective we look from).
Wheter past and future are unique (uncertain to us but with no freewill) or not (many-worlds theory) is a deep open debate.

And by the way, it's still somehow comprehensible what time may mean for material objects, but I still didn't hear an understandable reasoning of "what time may be" for radiation ("travelling" at the speed of light relative to any material observers regardless of their motion). Time flow is expected to be frozen, yet points distant from each other in spacetime are connected (without any "time interval" between them).
I have 2 threads posted in Relativity to ask for some light about this puzzle, I'm just an afficionado ...

 

[Sho'Nuff]

The definition I like best is : Time is the perception of change.

Consider this...

Does time exist if nothing changes/no events take place ?

Does change exist without someone to notice it ?

Relativity theory implies there is time dilation between one frame and another. For example, the faster a clock moves, the slower it runs, relative to stationary clocks. Satelites need to be corrected for this effect.
This suggests that even if time/change exists objectively the rate of this change is dependent on the observer.

It seems to me that time is a combination of objective time (physical changes) and subjective time (the emotional perception of this change)

Therefore the perception of change...


or you could go for something like : Time is what keeps everything from happening all at once

 

[Gerinski]

Talk about time that doesn't involve actual measuments tends to drift off into philosophy, unfortunately, rather than science

I fully agree in the sense of what objective science must be, but this thread is posted in the forum of Philosophy of Science, not in Relativity. Probably the people here is in fact concerned with discussing the interpretations of what time "means", what does it imply, what are the consequences of time being the way it is ...

I personally adhere to Sho'Nuff that time is just a perception of events that are "already existing out there" but appear to us in sequence. The fact that the sequence and it's changing rate may appear different for different observers supports this. It's the famous block-time issue, which brings on the table fascinating questions about freewill etc.

A relevant famous example is the possibility that a supernova or other cosmic catastrophe has already happened, yet it's destructive effects traveling at the speed of light have not reached us yet.
The destruction of the Earth "has already happened", but we have not perceived it yet (and there's no way we can ever know about it)

To me, not being an expert able to judge from the mathematical point of view, this only leaves 2 alternatives: or everything is already fixed or we live in Everett's "many-worlds" multiverse

 

[Sho'Nuff]

To me, not being an expert able to judge from the mathematical point of view, this only leaves 2 alternatives: or everything is already fixed or we live in Everett's "many-worlds" multiverse

I personally like the multiverse better since a fixed universe would theoretically allow peering into the future which in turn would present the oppertunity to cheat this future. This leaves me with a paradox.

 

[Gerinski]

I agree.
Again I want to stress that I'm no physicist to judge technically, but just from conceptual point of view, even if the multiverse theory is too hard to swallow for many people, to me it's the one which can best cope with the puzzles we face.