[PmbPhy]

Time cannot be defined. It's a primary concept like space. We can only then provide operational definitions for space and time intervals: measure time intervals with a clock and space intervals with a rod.

[talanum1]

It can be defined. See post 247 under this topic.

[Bill S]

It is possible to find a range of “definitions” of time, but each is relevant to the particular way in which the term is being used.  I agree with Pete, in that, if you consider time as a fundamental entity, that has an “existence” of its own, it probably cannot be defined.
 
One of the most concise definitions I have met is: “Time is the dimension on which the evolution of state of a system is allowed to occur”.  However, it is the evolution between points that is being measured.  We define intervals, and call these intervals time. Without the points, there would be no intervals. Without the intervals, there would be no time.

[PmbPhy]

It can be defined. See post 247 under this topic.

That post is wrong.

[Colin2B]

However, it is the evolution between points that is being measured.  We define intervals, and call these intervals time. Without the points, there would be no intervals. Without the intervals, there would be no time.

I don’t follow your reasoning Bill.
Let’s say we place some posts in the ground at an arbitrary distance apart and define that distance as 1unit. If we then remove the posts would you say that without those intervals there is no distance?
From my point of view when you say “We define intervals, and call these intervals time” I would say that we call those intervals measures of time.

[Bill S]

  A vacuum is devoid of light, unless you have matter inside it, although that may be arguable.

Arguable, indeed! If you put matter in it, is it still a vacuum?  We talk of having something in a vacuum, but is that like saying “there is nothing in here”, when we mean that what we are looking for is not there?  Is it a "narrow" usage of the term "vacuum"?

Then again; if putting something into a vacuum causes it no longer to be a vacuum, then there is no such thing as a vacuum, anywhere in the Universe.

[talanum1]

That post is wrong.

Is defining time using particles with fluctuating space as input wrong?

[PmbPhy]

That post is wrong.

Is defining time using particles with fluctuating space as input wrong?

Yes.

[talanum1]

That post is wrong.

Is defining time using particles with fluctuating space as input wrong?

Yes.

And your reason is ... ?

[PmbPhy]

That post is wrong.

Is defining time using particles with fluctuating space as input wrong?

Yes.

And your reason is ... ?

Same as held by any physicist, i.e. time is defined as what a clock reads. This is not a good definition because when you get into the details of what a clock is you end up with a circular definition.

See - http://www.exactlywhatistime.com/physics-of-time/

Your definition depends on the concept of fluctuation which in term relies on what fluctuation means. I was hoping to avoid getting into a debate about this since they never end. I'll just leave it here and point you to SR textbooks that you trust.

[talanum1]

I can leave out mention of fluctuations and simply state that flow of time depends on particles encountering points of space.

The new definition of time is attached.


Physics from Axioms clean.pdf (126.82 kB - downloaded 154 times)

[Bill S]

I'm certainly not qualified to comment on the maths in this paper, but just from reading the abstract, and looking a little beyond, I have to wonder about the possible translation from mathematical "reality" to any physical demonstration.  I look forward to further developments.

[PmbPhy]

I'm certainly not qualified to comment on the maths in this paper, but just from reading the abstract, and looking a little beyond, I have to wonder about the possible translation from mathematical "reality" to any physical demonstration.  I look forward to further developments.

You will never see me define something in an large article. Defining something like time, if its actually possible. takes only a short paragraph.

Take a look at - http://www.exactlywhatistime.com/
----------
We can measure time extremely accurately, but it is very difficult to define and explain exactly what time actually is
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What taluma1 is trying to do is state what time is by providing a specific example of a clock. Measuring something does not tell  you what it is.

ps - I wasn't going to post again  since I knew they'd be ignored but in this case I felt I had to speak up. Anything else, Bill, I'll PM you.

[Colin2B]

I can leave out mention of fluctuations and simply state that flow of time depends on particles encountering points of space.

It really doesn’t help. If the particles encounter points in space then they are moving and that requires pre-existence of time for it to occur. Your argument is circular/self dependent and does not define time.

Also, this is not the right place to discuss a new theory, so please confine it to the New Theories section

time is defined as what a clock reads. This is not a good definition because when you get into the details of what a clock is you end up with a circular definition.

As you also say Pete, it also leads to the confusion between the definition of the phenomenon and the definition of the measurement. That confusion leads to some very illogical conclusions not least of which is the title of this topic.

[talanum1]

It really doesn’t help. If the particles encounter points in space then they are moving and that requires pre-existence of time for it to occur. Your argument is circular/self dependent and does not define time.

My definition only implicitly requires the concept of time. It is my contention that implicit reference to the object being defined is allowable.

[PmbPhy]

As you also say Pete, it also leads to the confusion between the definition of the phenomenon and the definition of the measurement. That confusion leads to some very illogical conclusions not least of which is the title of this topic.

Here's a nice coincidence for you. I just received I book I ordered from Amazon called Graduate Methods of Classical Mechanics y V.I Arnold, Springer, 1989. From page 2

The text refers to the following as one of three elements of the Galilean structure
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Time - A linear mapping R^4 --> R from the vector space of parallel displacements of the real "time axis."
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 I don't consider this to be a definition of time though since that element does not tell us what R^4 is or what the "time axis" is.

Newton took time and space to be well-known concepts not in need of definitions.

[PmbPhy]

My definition only implicitly requires the concept of time. It is my contention that implicit reference to the object being defined is allowable.

Allowable by whom? What on God's earth does it mean to be allowable in defining things in physics? All you've done is to state a warm fuzzy feeling of what you think time is measured by. That's identical to saying that time is what measured by a clock. I've already mentioned that on an occasion or two.

[Bill S]

Thanks for the link, Pete. Looks like a lot of good stuff there. I’ve added to my Speed Dial, so any time I have a free moment I can dip in it.

Thanks, also, for offering to be there if when I run into problems.

[PmbPhy]

Thanks, also, for offering to be there if when I run into problems.

It's a pleasure. I'm here for you anytime my friend.

[Bill S]

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?