How do you define Time?

We use "time" to keep track of changes... Someone asked "change relative to what".... I suggest the answer to be "changes in position". Change in position can encompass and explain all kinds of changes... for example: an object moves from .a to .b represent a change in distance or position, another example: an object, say a ballon, getting bigger (matter particles at the surface of the ballon are actually getting away from each other- again changing positions), a third example: an object changing color - different kinds of photons are actually "flying" out of the object... All changes require motion. The concept of time is used by comparing one motion to another. Ie: we compare the motion of a car to that of a clock's needles. When we say "it's one o'clock", what we really say is that at the moment that the car is at a particular position, the needle on the clock is at the position of 1. We use cyclical motions to keep track of time, for example: the motion of a clock's needles, or the regular frequency of cesium atoms etc, in order to "count" time thus allowing us to compare changes with numbers - "time".... The universe is in constant motion hence time makes sense. Someone also mentioned that without motion time cease to exist... quite true...time is meaningless when nothing changes. Imagine a universe where nothing moves, nothing changes... will it even make sense to talk about tomorrow if tomorrow is the same as today ?

Good post bach_vu.

If nothing is moving, then there is no time present in the universe, and dare I say it, no consciousness?

If something is experiencing the non-motion universe, then there is time in the universe because there is something experiencing it, and thus according to our present knowledge, even though everything else in the universe but that one being is motionless, since a being is experiencing something, then there is time in the universe. However, such hypothetical scenario is improbable.

Agreed Ray,

A universe where only the observer moves is probably improbable. Also, having that observer move among a non-moving universe will still yield motion in that universe - the motion of that observer. But then again, you're quite right, such a hypothetical scenario is extremely remote, but.... enlightingly interesting hypothesis nonetheless.

This is a bit on the sidetrack....
I believe the different perceptions of time or its existence are quite normal and interesting. When we say "something exists", do we always mean that it is something tangible, something we can touch and measure? In physics, I believe that the answer would be Yes, always - unless something has matter or mass, it does not exist. But we live in everyday's life though, not in a physics lab...So what to make of time then? ... Since time, stripped down to its essence, is a relationship, a comparison between different motions or changes (as so rightfully put by Ray), it "exists" as a concept, the same way that a relationship, or a comparison is a concept. As long as the components of a relationship are there, then it makes sense to talk about that relationship, otherwise the relationship does not "exist".

So ....."something" can "exist" without ever having form or mass. It's all semantics.

I dunno Ray, Why don't you try it and see if it gets rid of some troubling paradoxes.

Like the differing ages of "Twins".

Frankly I am a bit pessimistic as to our abilities to explain time. Newton and Einstein also had a bit of difficulty with it so we shouldn't feel to bad if we don't get a handle on it.

Ray, I was refrerring to your post of Feb 19, 12:11 PM

bach_vu wrote:





That begs the question.

Saying we use time to track change or change to track time is to say that we use change to monitor change.

Hmmm interesting...

If changes are illusions created by memory, then I assume you are talking about human memory, correct? Memory can be of a different nature, for example: a series of still photos of an aging apple also constitute memory - a memory that is not influenced by human psyche or perception.

If the serie of photos were to be looked at in the present, then you can see the changes in the apple. It would be hard to argue that the changes were imaginary.

Btw, about the "Saying we use time to track change or change to track time is to say that we use change to monitor change.", you're not so far from the truth... Imagine using a stop watch to monitor a running sprinter. The change - ticking in the stop watch is indeed used to monitor another change - the sprinter's motion. I never thought of expressing the idea that way, but I'd agree with it.

For a great source on this kind of thing, read Richard Bach's "Illusions". I'm sure you will value the insight he provides, it's a great read, and not a long one either, you could probably read it in a couple hours if you tried. I found it really amazing in the words I read, I'm sure the effect would have been even stronger had most of it not gone over my head due to lack of focus.

akaMechsmith, could you elaborate?

Ray (re your post of Feb 20, 11:33)

Time, as we are aware of it seems to proceed at different speeds depending on your frame of reference. (largely an accelerated frame relative to a stationary one) Both of those terms again are relative

Gravity may be viewed as an acceleration. Einstein's quote probably.

This means that the perception of time is different due to the mass of our particular frame of reference compared to another different one.

This results in the famous "Twins Paradox" in which one twin stays home and ages normally but the other one hops a rocket ship and undergoes accelerations for a long time and doesn't age relative to the homebody. When the travelling twin returns home (via the principle of instantainity) he is the same age but a couple of generations have passed on Earth.
(A happy result is several science fiction stories by Asimov, amongst others)

But this has been shown to happen

In one experiment two separate "atomic" clocks accurate to three parts in a trillion were separated vertically at the Empire State Building and were shown to run at different speeds.

In another experiment ("The Harvard Tower Experiment") the energy levels (and hence the frequency{color}) of a ray of light were shown to change in as little as seventy five feet vertical difference on Earth.

In another experiment two atomic clocks were separated. One on Earths surface and one in a fast high altitude airplane. When compared they were found to have run at different speeds during the trip.

According to relativity theories this will happen.

Another thing that happens is that the wave length of light changes due to our perception of time. The colors we see are the effect of a certain number of light waves striking our eyes per second. If we accelerate ourselves towards a light source the frequency that we see will be "blue shifted". We will see light waves closer together and more energetic than they were at emission. The opposite effect happens when we recede from the scource. At either end of the spectrum you end up with an "infinity".

So basically "time occurs at the speed of light" according to relativity theory. I have found that the speed of light or the speed of time seldom have a one to one relationship. However relativity theory teaches that the speed of light is constant. This implies that the speed of time must vary.

If you are further interested I suggest that you try the "Advanced Physics Forums" on the net.

Also click on the "Harvard Tower Experiment"

There also was a pretty good thread on A2K, Science and Mathematics, concerning "Black Holes". A black hole being a region where no light, energy, or matter due to the accelerations of gravity (or warped space) can be viewed from outside it. This is a place where naturally time (if it is a function of light or distance (spacetime) must stop.

Frankly my searching has mostly resulted in finding out a lot of things that time is not

Lotsa luck, Mech (I'm gonna be late to work )

Thanks for that informative post.

Yeah, I've seen an old physics educational film about the twin paradox and Lorentz contraction, but I always seem to find it hard to grasp.

Could it be that, some sort of differences in energy causes differences in internal/microscopic speed of an object, such that time might differ relative to another?

Ray,

The Lorentz Contraction is nothing more than judging the length of a freight car by the time it takes to pass you. (Definition of time again)

At ten miles an hour it takes twenty seconds for a car to pass you and then you can deduce its length. At one hundred mph it will take two seconds. If you know its speed then you can deduce its length. The same deal with light waves. If you know its length then you can deduce its speed but then you must know the speed of the emitter relative to you as when you percieve it you percieve it as travelling at "c" or 300,000 meters per second. The wave length changes but not the speed to your perceptions. So now you understand how the "speed of time" messes up your perceptions.

IMO so far nobody has come up with a definition of time that doesn't have some paradoxes in it. I suspect that it may have something to do with the accelerations provided by gravity or perhaps "Quantum Mechanics" may come up with something.

I have a certain amount of hope for the "LIGO" (L aser I nterferometer G ravity wave O bservatory. (Search it) for if the observatory detects gravity wave anomalies happening at the rearmost dectector before the forward one then I suspect that that would show that time is faster than light. This would show that the speed of time is related to the speed of gravity rather than the speed of light. I suspect this.

There are several other reasons why I suspect that time has more to due with mass than "c" but I fear I may be getting deeper than you wish to go.

Anyways look up LIGO on the net. They have two sites, one in Louisiana and one in Washington state. Maybe we'll learn something

Time
Time is an invention of women who have nothing else to bitch about when I show up late.

Course it could also be just one of those things that we have used in one way or the other in time immemorial and other than our standard dictionary definitions haven't a clue.

What most of us experienced during our recent trip to Asia is a good example of how we perceive time. We spent three nights in Hong Kong, but by the time we were in Vietnam a few days later, it seemed as though our visit to Hong Kong was several weeks ago - or even a few months ago. Most on this trip expressed the same phenomenon; none could explain the reasons.

To understand time you must discard all human concepts of measurment. Past present and.future exist simultaneously. Try thinking of time as a capacity for a not yet existing volume .... like a door or window in a house, there yet not there.A capacity.

LIGO, interesting.

Wait, how could the speed of gravity be faster than light if gravity's speed is acceleration and it depend on mass?

Yeah, I have lots of questions.

Ray, re your post of Feb 22, 11:55

Convoluted thinking perhaps :wink:

Light appears to have mass (the mass-energy of a photon)

Light appears to be subject to gravity. (or warped spacetime if you prefer) Several experiments have shown that the path of light is curved when a massive object is near its path. Einsteins experiments in South Africa during an eclipse showed this. Gravitational "lensing" as seen on the Hubbell Telescope is another. The "Einstein Cross" which also has been observed is another ramification of the influence of gravity (or mass) on light.

But if light (when it's acting like light has mass then I think it fair to assume that light also has inertia. IF light has inertia then it will always lag behind the forces provided by gravity. For instance if you put a very heavy boat in a river the boat will never travel exactly as fast as the water. An example. Throw the boat in the river. Throw a packet of dye in the river beside the boat. Will the boat be in the center of the dye patch in a couple of days? As the river water speeds up and slows down due to various changes in the banks and bottoms the boat will always lag behind each change. More of the dye will get to the ocean before your boat will. Near an estuary the opposite would happen.

IF a photon is accelerated by gravity and possesses inertia (and it is shown that it is and it may) then the photon (as a wave) must always lag behind the total of the accelerations provided by gravity since all of the accelerations provided by gravity (relative to us) are going one way. (no estuary where time or gravity broadens and slows its forward motion) Actually it keeps getting faster, and light will keep getting further behind--continuously for some 13 to 15 billion years in our case.

IF my assumptions are correct (and I would be glad to be disabused of the notion) do you see what this does to the Big Bang-Expanding Universe theory or the Hubble Constant, or the "Cosmological Constant). ( Search them if you need to)

And if our notions of "Time" are based on the speed of light then any notion of time that we may entertain is equally fallacious.

But I am quite sure that I don't KNOW if our experience of time is based on the speed of gravity at our location but I do have some suspicions.
That particular view of time would get rid of some paradoxes.

I am glad you liked LIGO. Did you pretty much understand how they are supposed to work

I get a bit of a kick out of them ( the publishing powers that be) using a focused laser (light waves) to detect gravity waves and then denying that gravity influences the "red shift" or time .

Have a good evening---think hard, it's kinda fun

Human's passage of time is percieved in the basilar ganglilon area of the brain.

bach_vu



That's false,……

Changes, all changes, are memory dependent, are they not?


And if that is the case, lo-and-behold, there are no changes. I.e. a percept doesn't become a memory, it merely ceases to be.