What is the nature of "time"?

[nimble]

Does anyone know how this works? Is time a physical property of the universe? Or is it a man made concept?

[y_feldblum]

If I might be permitted to make up concepts, I would classify time along with space as a condition of existence (which is neither property nor concept). Duration, along with extent, is a property of existents, and it is a thing that can be measured.

[nimble]

so does that give the universe an infinite characteristic, since the universe is made of matter and matter cannot be created or destroyed?

[stephen_speicher]

Does anyone know how this works? Is time a physical property of the universe? Or is it a man made concept?

Time is a relationship that is both epistemological and metaphysical, much the same as are attributes of entities.

[Betsy]

Is time a physical property of the universe? Or is it a man made concept?

Time is a measure of motion just as length is a measure of extension in space.

If I roll a ball toward a wall, the "how far it went-ness" between where I pushed the ball and got it rolling and the wall that stopped the roll is the length of the roll. The "how long it took-ness" between my pushing the ball and it hitting the wall is the time of the roll.

Things in the universe move, but the universe as a whole CANNOT move. Where would it go?? Therefore motion, and thus time, does not apply to the universe as a whole.

[GoodOrigamiMan]

Time is a measurement of motion; as such, it is a type of relationship.  Time applies only within the universe, when you define a standard—such as the motion of the earth around the sun.  If you take that as a unit, you can say: “This person has a certain relationship to that motion, he has existed for three revolutions; he is three years old.”  But when you get to the universe as a whole, obviously no standard is applicable.  You cannot get outside that universe.  The universe is eternal in the literal sense: non-temporal, out of time.

Now two atomic clocks are synchronized and one is put into orbit for a while then brought back to earth. When it gets back the clock on earth is ahead of it.

Why?

[stephen_speicher]

Now two atomic clocks are synchronized and one is put into orbit for a while then brought back to earth. When it gets back the clock on earth is ahead of it.

Why?

You have to study physics -- specifically, the general theory of relativity and quantum mechanics -- to really answer your question. But, regardless, what has your question to do with the Peikoff quote you provided?

[stonebuddha]

The most important thing to understand about time is that it is NOT the driving engine behind causality. Things change not because time is moving forward, but because of the interaction of molecules, atoms, electrons, etc. There is no "ultimate clock" which is ticking away & regulating the universe.

Time is just a measurement no different than the gradations on a ruler. You wouldn't say that a tree is getting taller BECAUSE it covers more gradations on said ruler. Instead you would say that the tree is getting taller because it is absorbing nutrients from the ground and its internal processes are elongating its limbs.

So why would you say that a person is getting older because the second hand of a clock is moving?

[GoodOrigamiMan]

You have to study physics -- specifically, the general theory of relativity and quantum mechanics -- to really answer your question. But, regardless, what has your question to do with the Peikoff quote you provided?

I understand the theory of relativity. However sometimes time is taken to be some sort of 4th dimension. This works out as far of the math but I want to know if there was a different way to approach relativity. I haven’t found a lot on Objectivist metaphysics, the best source I have so far has been OPAR. As far as the quote goes I’m having trouble substituting that definition of time into the theory of relativity. In other words I’m having trouble relating the theory of relativity to the entities themselves. Is it obvious that I’m confused about the matter?

[AndrewSternberg]

I think I am also somewhat confused about what time is?

As of now, I view it as a measure of change similar to the way Peikoff describes it as a measure of motion. If nothing ever changed, there would be no concept of time (among other things). The same goes for motion.

What is the difference between time as change and time as motion?

[stephen_speicher]

I understand the theory of relativity.

Okay. Good.

As far as the quote goes I’m having trouble substituting that definition of time into the theory of relativity.  In other words I’m having trouble relating the theory of relativity to the entities themselves.

But in general relativity that is exactly what the stress-energy-momentum tensor (sem) does. The connection from relativity to entities in the physical world is via the sem, which relates the Einstein field equations to reality in how one models the matter. So, for instance, for your clock orbiting the Earth, the gravitational time dilation depends on the quadrupole moment of the Earth, and therefore a perfect fluid sem would not apply. This is one reason why, on this level, a connection to quantum field theory is ultimately required.

[stephen_speicher]

I think I am also somewhat confused about what time is? 

As of now, I view it as a measure of change similar to the way Peikoff describes it as a measure of motion.  If nothing ever changed, there would be no concept of time (among other things).  The same goes for motion.

What is the difference between time as change and time as motion?

Well, first of all, motion is change, i.e., change in position. I personally think that the clearest way to look at the whole issue is to see time as a relational concept, and, as Ayn Rand put it in ITOE (p. 261), time "is a change of relationship." You might want to read that whole section in ITOE.

[AndrewSternberg]

Well, first of all, motion is change, i.e., change in position. I personally think that the clearest way to look at the whole issue is to see time as a relational concept, and, as Ayn Rand put it in ITOE (p. 261), time "is a change of relationship." You might want to read that whole section in ITOE.

Yes, perhaps a re-reading is called for. Thanks for reminding me about that section.

[GoodOrigamiMan]

But in general relativity that is exactly what the stress-energy-momentum tensor (sem) does.

I don't know much about 'sem'. Can you recommend any sources?

[stephen_speicher]

I don't know much about 'sem'.  Can you recommend any sources?

I only mentioned the tensor because you said "I understand the theory of relativity" when I mentioned general relativity. The stress-energy-momentum tensor represents one side of the Einstein field equation, a coupled system of nonlinear partial differential equations. There are relatively few exact solutions to the field equations, so they are often solved numerically and/or put into a linearized form. It is usual to specify the stress-energy-momentum tensor for some given form of matter and then solve for the metric. If this is all foreign to you, then you do not understand general relativity and any sources for this would essentially require a technical course in the subject with appropriate knowledge of differential geometry. However, there is an excellent non-technical source (General Relativity From A to B, Robert Geroch, The University of Chicago Press, 1978/1981) which only requires high school level math, but on this level the tensor nature of the field equations cannot be detailed. Nevertheless, you might enjoy reading that non-technical book to get a better sense of what it is all about.

But, getting back to the original issue about time and relativity, I can at least briefly explain in a non-technical way a basic connection in the special theory of relativity (SR). It is well-known, even amongst many laymen, that for two observers who are in uniform relative motion to each other, each will measure the other's clock to tick at a slower rate than their own. The tick rate of a clock is nothing more than the interval between two events, and for each observer their own clock continues to tick at its usual rate. The discrepancy that exists between the observers is simply a consequence of our means of observation, a measurement process dependent on light whose speed is measured to be constant by all observers. So time as a relational concept holds true also in relativity, and the measured time between events is subject to the relativity of simultaneity for different observers.

[GoodOrigamiMan]

I accidentally ran into a really good web page on time today. Defiantly worth looking at:

http://www.quackgrass.com/time.html#intro

[stephen_speicher]

I accidentally ran into a really good web page on time today.  Defiantly worth looking at:

http://www.quackgrass.com/time.html#intro

I would recommend that no one waste their time on this piece. Mr Miller, the author of the article, demonstrates a poor grasp of both Objectivism and physics. That Mr. Miller finds it necessary to drag Ayn Rand and Objectivism into his ignorant view of physics, is rather obnoxious. The inconsistencies and contradictions to Objectivism should be obvious to anyone familiar with the philosophy, and the ignorance of physics and experimental fact should be apparent to anyone knowledgable in physics.

[GoodOrigamiMan]

I would recommend that no one waste their time on this piece. Mr Miller, the author of the article, demonstrates a poor grasp of both Objectivism and physics. That Mr. Miller finds it necessary to drag Ayn Rand and Objectivism into his ignorant view of physics, is rather obnoxious. The inconsistencies and contradictions to Objectivism should be obvious to anyone familiar with the philosophy, and the ignorance of physics and experimental fact should be apparent to anyone knowledgable in physics.

I didn't notice anything that was that bad... What did I miss?

[stephen_speicher]

I didn't notice anything that was that bad... What did I miss?

The entire article is riddled with errors, but I already wasted too much time reading it to spend more time analyzing and detailing it. His basic premise, that upon which everything else is built, is "time is a measure of existence." If you do not know why that is not the Objectivist view of time, then read Ayn Rand's ITOE. His major conclusion, ultimately derived from his basic premise, is that there is such a thing as "absolute time." If you do not know why that is wrong, then study the physics of the past one-hundred years.

[GoodOrigamiMan]

It is often said (following Aristotle) that time is a measure of motion, but this misses the full generality of time. Aristotle himself was not misled by his formulation, for he went on to say that because time is a measure of motion, it is also a measure of rest. Since moving or not-moving, changing or not-changing, exhaust the possibilities for anything at all, Aristotle's view really boils down to the one stated here: time is a measure of existence.

One thing Michael fails to do is separate the concept of time from the concept of duration. So in that sense he is fundamentally wrong about calling time a measurement of anything. But even Peikoff said “Time is a measurement of motion…” isn’t this wrong? Time, to be a parent concept, must omit measurement. Duration is a measurement of time - time is not a measurement of itself. Can a concept be a measurement of it’s own conceptual common denominator?

Saying, time is a change of relationship. What I don’t like about it is that, time is a change of relationship. Wouldn’t it be more appropriate saying time is change in relationship? A change seems to imply duration because it is finite. The concept of time is grasped thru perception of a change in relationship here and a change in relationship there, but once grasped time is the abstraction for change in relationship not a change. If I am not mistaken ‘a’ in this context is working as an indefinite article meaning that the time is unspecified (which makes sense) however it still leaves it open to interpretation that it could be specified and a specified time (or a measured time) would be a duration, right?

As for “Time is a measure of existence”, would it’s true equivalent be: “Duration is a measurement of change of relationship of existence”

Anyways I sympathize with that Michael’s wording because of how time and existence are related. If nothing existed there would be no time. However time is not a measurement of existence. But then again…

[W A Dunkley]

Everything exists; Existence cannot be added to, or subtracted from. The axiom does require the rejection of a changing world (as first recognized by Parmenides), but the fact of our experience of a world in motion can be reconciled with logic, by embracing four-dimensionalism. In such a view, to observe change is to observe the differences between different parts of the same four-dimensional whole, but the parts (ultimately) do not change and the whole does not change. Such a view of change agrees with the axiom: all A is A, and it does not deny the perceptual evidence of motion. It is, rather, a reinterpretation that leads to a very difference world view with profound implications. It is a view that holds that the passage of time is psychological (i.e., pertaining to the way one perceives the dimension of time, not an actual component of the physical universe) and existence is an unchanging four-dimensional totality.

[stephen_speicher]

But even Peikoff said "Time is a measurement of motion..." isn’t this wrong?  Time, to be a parent concept, must omit measurement.  Duration is a measurement of time - time is not a measurement of itself.  Can a concept be a measurement of it’s own conceptual common denominator?

First, you misunderstand the role of measurement-omission in concept formation. It is not the word "measurement" itself which is omitted, but rather all instances of measurement, all specific measurements. Second, time is a relational concept, but it is defined ostensively. Any subsequent definition or characterization will, implicitly or explicitly, be abstracted from the notion of time itself.

Saying, time is a change of relationship.  What I don’t like about it is that, time is a change of relationship.  Wouldn’t it be more appropriate saying time is change in relationship?

No. A change in relationship would imply a different kind of relationship, which is not relevant to the sort of change that involves time.

Anyways I sympathize with that Michael’s wording because of how time and existence are related.  If nothing existed there would be no time.

If nothing existed there would be no anything. I fail to see what you sympathize with, since the statement itself is not at all informative.

[Thoyd Loki]

Everything exists; Existence cannot be added to, or subtracted from. The axiom does require the rejection of a changing world (as first recognized by Parmenides), but the fact of our experience of a world in motion can be reconciled with logic, by embracing four-dimensionalism. In such a view, to observe change is to observe the differences between different parts of the same four-dimensional whole, but the parts (ultimately) do not change and the whole does not change. Such a view of change agrees with the axiom: all A is A, and it does not deny the perceptual evidence of motion. It is, rather, a reinterpretation that leads to a very difference world view with profound implications. It is a view that holds that the passage of time is psychological (i.e., pertaining to the way one perceives the dimension of time, not an actual component of the physical universe) and existence is an unchanging four-dimensional totality.

Thank you! You just gave me a new concept. Rationalist word salad!

I recommend referring to reality once in a while.

[y_feldblum]

Mr. Speicher,

Some technical questions that everyone else can ignore.

What do "coupled" and "uncoupled" mean, in general and as applied to the contexts of the GRT field equations and the field equations of electromagnetism? Why is (D'Alembertian A = 4 pi J) uncoupled and (G = 8 pi T) coupled?

What do "linear" and "nonlinear" mean? I'm going to guess that, as in electromagnetism, linear fields are fields that, when superimposed (when two or more sources are close to each other), add linearly. Ie, do you mean that the gravitational effect on the metric of two or more sources is different from the sum of the effect of each of the sources individually? Or is it something different?

Can you give me any more examples of finding the solutions (ie a metric) for some given kind of stress tensor? I think the Shwartzchild metric is the solution for the surface and exterior of a star; I've heard mention of a Kerr metric, which I think is the solution which (somehow) illustrates at the same time the observations of an observer far from and one on the horizon of a (collapsing?) black hole, which the Shwartzchild metric couldn't do. Also, if you could clarify exactly what these two metrics are, that would be great.

Also, though you didn't bring it up, how are point charges and singularities (point masses?, eg within a black hole's horizon) different?

I have an interest in but no formal training in theoretical physics. If you could answer these questions, or direct me to any articles (preferably free & online & perhaps not too technical), I would appreciate it. Thanks.

[W A Dunkley]

Thank you! You just gave me a new concept. Rationalist word salad!

I recommend referring to reality once in a while.

One simple straightforward question from the rational salad:

Does the past and future exist?

When referring to reality, is it not appropriate to consistently affirm it. The three-dimensional view can't decide on the ontological state of past and future. It implies that only "now" exists, but yet, also speaks of a non-existent past and future. And the future is somehow less real than the past.

Four-dimensionalism does not fail to reference reality, it interprets the information we have about reality in a way that is not contradictory.