Question About Time

[Grendizer]

Hey all,

 

I've been taught that time is a rate of change. Well, change could have many meanings. So my question is very specific:

 

What is "change" refering to? change in life, change in form, change in characteristic? What is change?

 

I am kind of looking at the definition in a weird way. Everything is the universe seems to be dying. So could the meaning of "change" refer to the "death" of matter? For example, time = rate of "death" of matter?

 

I hope I put my thought clearly.

 

Thanks,

[iNow]

I see it as increasing disorder (or decreasing order) in a system, also known as entropy. Systems tend to move from more ordered to less ordered states (when no energy is added from external systems), so we have an arrow of time due to the increasing entropy we see.

[Grendizer]

Ok, but the question is still not cleared.

 

Atoms are under gradual death. Can that be the meaning of change? death?

[iNow]

Meaning is a subjective topic. Meaning is given to things by us within our minds. Change is any alteration of state. Also, things can change without dying, but even that depends on how you define death. This conversation is quickly moving into the realm of philosophy and out of the domain of physics.

 

Also, on your OP, you mention defining time as "rate of change." I find this definition unsatisfying because it uses the concept of "rate." Rate requires time to be defined... cycles per second, miles per hour, decays per century... all of these examples require a preexisting notion of time, so to use the concept of "rate" within your definition of time is circular and I'm not sure that will help alleviate the confusion.

 

Time is one of those concepts that is profoundly resistant to a simple definition.

 

http://www.pbs.org/wgbh/nova/physics/Sagan-Time-Travel.html

[Grendizer]

Thank you, iNow. I can see what you are talking about. I guess when it comes to subjects like this, it becomes more philospoy then science. I think am happy with the answer, even thou it does not answr fully my question. Thanks again

By the way, what I mean by "death" is matter going back to its fundemental state, atomic state. Example, H2O becoming H, H and O.

[JohnCli]

If we leave something alone, the natural tendency is for it to go from a state of order to disorder. The only way to reverse this situation is by creative

intervention. One result of this law is if you want to create something, you must expend energy to the point that the disorder you generate is more than the order you create. In the transfer of energy from one point to another, there is always some waste left over.

[Cassandre]

Regretfully common textbooks say little about "time", and thus I have no other references than common history and logic for answering your question.

I think (pretty sure) that "time" first off all related to the daily and yearly cycles. Thus sun dials and mo(o)nths are among the oldest time sensors. Common time sensors measure the progress of change of something observable, such as the change of position of the sun or moon or the recurring motion of a quartz crystal; and the rate of such a change is a frequency. Constant frequency devices are therefore popular for clocks.

 

However for example a C14 "clock" is based on a (in that sample) non-recurring change of radioactivity, and the change rate is not constant. So, "dying" could make some kind of clock, but that certainly isn't a fundamental property of "time". "Change" as in "time" refers to observable changes in repeatable physical processes that can serve as a basis for comparison ("time measurement"). Just my 2 cts.

Edited January 14, 2013 by Cassandre

[michel123456]

 

If we leave something alone, the natural tendency is for it to go from a state of order to disorder. The only way to reverse this situation is by creative

intervention. One result of this law is if you want to create something, you must expend energy to the point that the disorder you generate is more than the order you create. In the transfer of energy from one point to another, there is always some waste left over.

 

(bolded mine)

But gravitation makes things come together.

And an orbit is not what we call a state of disorder.

[swansont]

(bolded mine)

But gravitation makes things come together.

And an orbit is not what we call a state of disorder.

 

Gravity, alone (i.e. without dissipation) will not do this; this is one of the issues with dark matter. The dissipation is where the entropy increase occurs.

[michel123456]

 

Gravity, alone (i.e. without dissipation) will not do this; this is one of the issues with dark matter. The dissipation is where the entropy increase occurs.

 

That need some explanation.

[swansont]

Things don't stick together (like a planet) unless the constituent particles release energy. In releasing energy, the entropy of the system will increase.

[Maxila]

The cause of any change has a strong empirical basis; at the most fundamental level it is the change of position of particles in space. Empirically speaking this scales up to how time works on a macro level; any change you can think of, at its root, is caused by a change of position of energy in a space (energy in some form, i.e. matter, etc.). Remember a change of position does not have to be linear.

 

The two measurable physical quantities that are used to derive a time are, distance, and a change of position energy that relates to a distance, the latter is more commonly thought of as speed. The reason I didn't use the word speed is because scientifically speed is defined as a change of position in distance as it relates to time. That can create a circular argument of what time is, and the illusion that empirically time is some sort of entity or dynamic. I am only talking about empirical observations of time and change, not the aspects of time that can appear in mathematical constructs but have had no empirical basis.

 

All clocks whose functions I have studied (including atomic clocks), measure a change of position energy as it relates to a specific distance in order to derive its units of time. Those time units than represent any equivalent ratio of that distance over that change of position energy. An easy visual example one can imagine to consider these dynamics is, one Earth rotation representing one day of time. The distance, change of position energy relative to a distance, time, and the ratio relationship of time = distance / change of position energy, are all easily apparent. On careful examination it is also apparent in the function of clocks, including official time standard atomic clocks.

 

Empirically time is the measurement of a physical quantity in a similar way mass is. Whereas mass measures a quantity of energy, time measures a change of position energy as it relates to a change in distance, and the cause of change itself is simply a change of position of energy in any form.

 

I hope that was a bit helpful?

 

Maxila

Edited January 15, 2013 by Maxila

[swansont]

All clocks whose functions I have studied (including atomic clocks), measure a change of position energy as it relates to a specific distance in order to derive its units of time. Those time units than represent any equivalent ratio of that distance over that change of position energy. An easy visual example one can imagine to consider these dynamics is, one Earth rotation representing one day of time. The distance, change of position energy relative to a distance, time, and the ratio relationship of time = distance / change of position energy, are all easily apparent. On careful examination it is also apparent in the function of clocks, including official time standard atomic clocks.

 

How is the change in the spin state of an electron interpreted as a change in position?

[Maxila]

 

How is the change in the spin state of an electron interpreted as a change in position?

 

I only know the basics of quantum mechanics, I had to check and that I was stating this correctly; electron spin represents angular momentum, which has both magnitude and direction. That by itself seems implicit with a change in position?

 

Since I am not that versed in quantum mechanics, I would appreciate if you explained to me how a change in spin may not be interpreted as any kind of change in position (if that's what you were saying)?

 

I was careful to say I was only talking about what is observed empirically, I don’t know if it is true of spin; however I do know many quantum states are probabilities of outcomes and not directly observable?

 

Maxila

Edited January 15, 2013 by Maxila

[michel123456]

Hey all,

 

I've been taught that time is a rate of change. Well, change could have many meanings. So my question is very specific:

 

What is "change" refering to? change in life, change in form, change in characteristic? What is change?

 

I am kind of looking at the definition in a weird way. Everything is the universe seems to be dying. So could the meaning of "change" refer to the "death" of matter? For example, time = rate of "death" of matter?

 

I hope I put my thought clearly.

 

Thanks,

Here below my views:

 

Change is tightly related to time.

 

At T=0 you have situation A

At T=1 you have situation B

 

"change" is what we call when the same entity is recognized under A and B.

 

For example you have an Apple and a Bed. Since the Apple and the Bed do not share an enough amount of common properties, we do not say that the Apple changed in Bed. That is common sense.

 

If you take 2 Apples separated by a distance, although the 2 Apples share many properties, again we don't recognize that as a change, but as 2 different apples. The reason is not the fact that they are 2 apples, but the fact that there exist space between the 2 apples "at the same moment"

 

1.Now if you take the 2nd apple and put it exactly at the same place (and time) with the first one, you will realize that it is not possible. That is common sense too, but in physics it is a specific property.

 

2. In order to have "change", you must take only one apple and for example move the apple to new spatial coordinates. That is; you will have 2 apples at 2 different spatial coordinates (like in 1.) but at different time coordinates. That is a situation where you must care about recognizing carefully that it is the same Apple and not 2 different objects. (illusionists know about that)

 

3. Or do nothing, then the apple will have "moved" to new temporal coordinates. In the absence of any physical interaction, that would not be a change. But since all 4 fundamental interactions are acting over time, macroscopically we interpret the apple standing at rest on the table as a change. But maybe that is circular thinking.

 

About birth & death, I think it is completely wrong. One of the most powerful law of physics is about conservation of matter-energy. What we observe is that we call "birth" is a transformation, and what we call "death" is another transformation. Applying both terms of 'birth" and "death" to physics should be an analog to "creation of mass-energy" and "loss of mass-energy", both of which are concepts that circulate here and there but do not rely on observation. IMHO.

Edited January 16, 2013 by michel123456

[swansont]

 

I only know the basics of quantum mechanics, I had to check and that I was stating this correctly; electron spin represents angular momentum, which has both magnitude and direction. That by itself seems implicit with a change in position?

 

Since I am not that versed in quantum mechanics, I would appreciate if you explained to me how a change in spin may not be interpreted as any kind of change in position (if that's what you were saying)?

 

I was careful to say I was only talking about what is observed empirically, I don’t know if it is true of spin; however I do know many quantum states are probabilities of outcomes and not directly observable?

 

Maxila

 

It's a change in orientation of the vector. The electron's position does not need to change. The electron doesn't have a defined position anyway, so talking about its location when you aren't measuring it loses meaning in QM.

[Maxila]

2. In order to have "change", you must take only one apple and for example move the apple to new spatial coordinates. That is; you will have 2 apples at 2 different spatial coordinates (like in 1.) but at different time coordinates. That is a situation where you must care about recognizing carefully that it is the same Apple and not 2 different objects. (illusionists know about that)

 

3. Or do nothing, then the apple will have "moved" to new temporal coordinates.

 

One of the things I have been observing about empirical change is if you look carefully at the reference to what has changed it always seems to be coincident with some form of energy changing position in space. Let’s take a look at the reference to the apples in #2 and the temporal coordinates # 3.

 

The change for the apple in #2 is an axiom so we can move on to the temporal change in #3. There are many things one can choose to point to the reference for this change, a clock, stellar bodies, an experience of a passing duration for ourselves, etc. Look carefully at any of these and at some level the temporal change must be referenced to some form of energy/particles (at the fundemental level that scales up to a macro level) changing position. If we kept those apples in # 3 and every particle in the Universe also did not change position, there would be no temporal change to reference.

 

The only reference that could be made for any kind of temporal change in that case might be to a body outside the Universe that did experience some form of a change of position, because if every particle of energy in the Universe did not change position there would be no way to reference any change in time.

 

Maxila

 

 

It's a change in orientation of the vector. The electron's position does not need to change. The electron doesn't have a defined position anyway, so talking about its location when you aren't measuring it loses meaning in QM.

 

If I recall correctly the electrons position in QM is considered to be something like a probability cloud around the nucleus until it’s measured? I was talking about observed empirical change.

 

I've been looking at time for a while in many aspects, I have no agenda on what I think it should be, and I’m trying to see its empirical characteristics objectively. So far, that any empirical change in time is coincident with a change of position (or a change in position is coincident with a change in time), has held up to the evidence I have looked at; also that any empirical change is fundamentally the result of some form of a change of position of energy (energy of any form).

 

While it has held up to relativistic empirical evidence, it does not hold up to some relativistic mathematical constructs that unfortunately will never be observable even if they exist (things like the infinite time of a singularity, and zero time of a photon frame). In any event it is remarkable how much evidence there is for a very precise empirical definition of time, that even if not completely compatible with all theoretical models, seems to be compatible with the observable evidence those models predict? So far I have only found unobservable mathematical time constructs where inconsistencies exist; however I make no claims other than merely pointing out some of the observational evidence I have come across to date. In fact I am continually looking for inconsistencies and I would appreciate being directed towards such evidence.

 

The one problem I've had in discussing the empirical evidence of time characteristics is some peoples idea of time is so ingrained they can't overcome subject reasoning and discuss the evidence factually or deductively. I can understand it because my own ingrained thoughts of time caused me trouble seeing facts clearly when I first started examining it.

 

Maxila

Edited January 16, 2013 by Maxila

[swansont]

If I recall correctly the electrons position in QM is considered to be something like a probability cloud around the nucleus until it’s measured? I was talking about observed empirical change.

Yes. There is none in this case — you aren't measuring a position.

 

I've been looking at time for a while in many aspects, I have no agenda on what I think it should be, and I’m trying to see its empirical characteristics objectively. So far, that any empirical change in time is coincident with a change of position (or a change in position is coincident with a change in time), has held up to the evidence I have looked at; also that any empirical change is fundamentally the result of some form of a change of position of energy (energy of any form).

I don't understand what "position of energy" is supposed to mean. They aren't the same thing and need not rely on each other.

 

[Maxila]

 

Yes. There is none in this case — you aren't measuring a position.

 

I don't understand what "position of energy" is supposed to mean. They aren't the same thing and need not rely on each other.

 

Perhaps I am using the word too broadly? Since energy in one form or another makes up the observable "stuff" of space I was trying to refer to all that would encompass, a particle, a wave, matter, an electro-magnetic field, etc. Essentially what I was trying to say is a change of position of anything that can be empirically observed or measured.

 

I am always grateful if someone is willing to show me how to express a thought correctly, or with more clarity, if you have any suggestions?

 

Maxila

[swansont]

 

Perhaps I am using the word too broadly? Since energy in one form or another makes up the observable "stuff" of space I was trying to refer to all that would encompass, a particle, a wave, matter, an electro-magnetic field, etc. Essentially what I was trying to say is a change of position of anything that can be empirically observed or measured.

 

I am always grateful if someone is willing to show me how to express a thought correctly, or with more clarity, if you have any suggestions?

 

Maxila

 

Energy is a property of things, and things related to position (and trajectories, especially) are not well-defined at this level, and cannot be observed/measured below the threshold the the Heisenberg Uncertainty principle.

[Maxila]

 

Energy is a property of things, and things related to position (and trajectories, especially) are not well-defined at this level, and cannot be observed/measured below the threshold the the Heisenberg Uncertainty principle.

 

Thank you, I'll try to be more careful how I use the word in the future.

 

You mentioned the "Heisenberg Uncertainty Principle" and I had considered an aspect of it with the empirical time evidence I've been examining. It seemed sensible to consider that if time were the measurement of a distance / a change of position energy relative to distance, than the more accurately you determined a particles specific position there is less information available to determine its momentum, and of course the opposite, the more accurately you determined its change of position velocity the less accurately you can determine a specific position.

 

In any event it seems very compatible with why such an uncertainty must exist and I thought it interesting you mentioned it.

 

Maxila

Edited January 16, 2013 by Maxila