[PmbPhy]

My definition only implicitly requires the concept of time.

I’m fascinated by the idea that the concept of time is “only implicitly” required.  Does that mean that your definition does not require a time concept?  If so, how does it work if any movement/change is involved?

That's the main problem with his and others definition. It requires the concept of motion/change which are defined in terms of time. Thus it's a circular definition and fails as one. I.e. time is defined in terms of motion/change which is defined in terms of time.

There's a book called The Philosophy of Space and Time by Hans Reichenbach, Dover Pub. which some might find interesting to read.

[talanum1]

The definition: "time is what a clock measure" is circular since a clock has to be calibrated, hence you need time to define time. With an atomic clock the definition: "x oscillations per second" is circular since oscillation requires motion.

My definition is just implicitly circular. I guess it is circular then.

[PmbPhy]

The definition: "time is what a clock measure" is circular since a clock has to be calibrated, ...

Wrong. A clock need not e calibrated. It can merely be built and used it's primary time interval as the unit of time. Do I need to explain what a primary time interval is? Think about a pendulum clock.

[talanum1]

A clock's parts move, which implies time: circular.

One needs a dynamic input to define time, by basic reasoning.

[Bored chemist]

One needs a dynamic input to define time, by basic reasoning.

That doesn't actually mean anything.

[Bill S]

My definition is just implicitly circular. I guess it is circular then.

If that is seriously intended as an answer to the questions in #279, there is probably little point in asking any more questions. 

[Bill S]

Do I need to explain what a primary time interval is?

Reason v dogmatic thinking?  You could be on to a looser, there, Pete.

[talanum1]

I’m fascinated by the idea that the concept of time is “only implicitly” required.  Does that mean that your definition does not require a time concept?  If so, how does it work if any movement/change is involved?

If I use time in the definition of time the definition is circular. As I stated: a dynamical input is needed. This makes any definition of time circular.

How are you going to define time in only static terms?

[Bill S]

How are you going to define time in only static terms?

That depends on what you mean by "static terms".  If you mean there is no motion/change in the Universe, then time has no meaning, or role in the scenario, and therefore no definition.

The question would then arise as to whether a totally static universe is even a physical possibility.

[talanum1]

That depends on what you mean by "static terms".

I mean: words and concepts not using motion/change.

If you mean there is no motion/change in the Universe, then time has no meaning, or role in the scenario, and therefore no definition.

So, it's impossible to define time in static terms?

[Bill S]

So, it's impossible to define time in static terms?

Whatever may, or may not, be possible mathematically; I would be interested to see a practical example.

[Bill S]

http://www.exactlywhatistime.com/other-aspects-of-time/eternity-and-immortality/

I’m not recommending this as a good read.  IMO it is an emporium of philosophical and religious verbosity. Even so, it includes one or two points that may be worthy of comment.  Eg:

  However, if time actually is quantized, it is likely to be at the level of Planck time (about 10^-43 seconds), the smallest possible length of time according to theoretical physics, and probably forever beyond our practical measurement abilities.

If time is just the conventional measure we apply to duration between changes; one has to wonder, in what sense it could be quantized.  Appealing to the concept of Planck time does not really make any difference, as Planck time has no special significance beyond theoretical calculations.

[Just thinking]

No, Time and light are not associated. A light year is a measurement of distance.

[talanum1]

I have since refined the definition so it's no longer circular. See attachment.


Physics from Axioms clean.pdf (88.61 kB - downloaded 93 times)

[Just thinking]

Time is the passage of existence reality as we know it to be.

[TommyJ]

Entropy - arrow of time.
Time exists in observations, equations, theories and laws. It is a part of apparatus that we currently have working best for the Universe understanding.
It is determined by an observer and perceived  as a human.

Think about that idea. Does light experience time? From the perspective of a photon, it's emitted, and might exist for hundreds of trillions of years, but for the photon, there's zero time elapsed between when it's emitted and when it's absorbed again.

[Eternal Student]

Hi.

Time exists in observations, equations, theories and laws. It is a part of apparatus that we currently have working best for the Universe understanding.

   Not sure about the part  "Time exists in observations". 

It is determined by an observer and perceived  as a human.

   Humans perceive the passage of the time a certain way, if that's what you mean.   We all instinctively understand the passage of the time.  However, child psychologists may argue about exactly when a child forms an awareness of time.

Think about that idea. Does light experience time?

    Using your earlier comments, a brief answer can be given:   A photon is not a human being.  So it does not experience time as a human being would.

From the perspective of a photon, it's emitted, and might exist for hundreds of trillions of years, but for the photon, there's zero time elapsed between when it's emitted and when it's absorbed again.

    Subject to limitations described earlier, this is true enough.   Supposedly Einstein thought about something similar - what it would be like to ride along with a photon.
    We could be annoying and state that the entire statement that it "might exist for hundreds of trillions of years" is meaningless unless we bring in another observer who is not travelling with the photon.  The photon may exist for hundreds of years as far as some other observer is concerned but as you stated, there is no elapsed time for the photon.

Best wishes to you.

[gem]

Hi all

    Subject to limitations described earlier, this is true enough.   Supposedly Einstein thought about something similar - what it would be like to ride along with a photon.
    We could be annoying and state that the entire statement that it "might exist for hundreds of trillions of years" is meaningless unless we bring in another observer who is not travelling with the photon.  The photon may exist for hundreds of years as far as some other observer is concerned but as you stated, there is no elapsed time for the photon.

Best wishes to you.

If no time elapsed in the reference frame of the photon for  hundreds of trillions of years what universe is it travelling through and where was it generated that it’s energy never changes over time 🧐

[Just thinking]

Time is a function of matter when the first appearance of matter came into existence time began. Matter can not exist without time, time can not exist without matter. Time and matter are working together to create a passage as the passage is the essence of time.

[Eternal Student]

Hi.

If no time elapsed in the reference frame of the photon for  hundreds of trillions of years what universe is it travelling through and  that it’s energy never changes over time 🧐

   Difficult to provide an answer in the way you may want.
     The photon has no rest frame.  In any inertial frame of reference the photon is still going to be moving with speed c.  Could you clarify what you mean by "the reference frame of the photon" as you have used in your question.
   We can push the usual definition of a co-ordinate system.  We can imagine a co-ordinate systems in which the photon is at rest.  This is an extremely degenerate co-ordinate system.  It fails to separate many distinct events in spacetime that describes the universe for most other observers.  So we cannot answer your question "where was it generated" - a description in the co-ordinate system of the photon would fail to describe a unique location and time for most observers.
    You asked "what universe is it travelling through"?  The photon would usually be considered to be in the same universe but experiences it differently to most other observers (although the photon isn't human and doesn't experience anything like we do anyway).

Besy wishes to everyone.