what is time?

[dad]

What is time according to science or in reality? I don't think they really know, do they? Let's see.

[Strange]

Time in general relativity is modelled as the fourth dimension of the space-time manifold. I don't know how it is represented in quantum mechanics.

 

As for reality, that is a matter for philosophers and you will probably find as many opinions as there are philosophers.

[petrushka.googol]

There is no absolute time. It is a frame of reference which serves as the fourth dimension in spacetime.

[dad]

Time in general relativity is modelled as the fourth dimension of the space-time manifold. I don't know how it is represented in quantum mechanics.

 

As for reality, that is a matter for philosophers and you will probably find as many opinions as there are philosophers.

 

OK. So you feel reality is outside of the realm of science, and we should ask others. As for relativity, time is 'modeled' a certain way. So it seems that what you offer is a limited concept and definition of time.

There is no absolute time. It is a frame of reference which serves as the fourth dimension in spacetime.

 

In the theory of relativity, yes. Guess there is no way to test time far away?

[Strange]

OK. So you feel reality is outside of the realm of science, and we should ask others. As for relativity, time is 'modeled' a certain way. So it seems that what you offer is a limited concept and definition of time.

 

Yes, and yes.

[dad]

 

Yes, and yes.

 

Let's say you are 40 years old. That time is due to relativity?

[Strange]

Let's say you are 40 years old. That time is due to relativity?

 

I don't really understand the question. Relativity is about the relationship between measurements made by observers in different frames of reference. So someone in a different frame of reference could have measured my lifespan as more or less than I do.

[dad]

 

I don't really understand the question. Relativity is about the relationship between measurements made by observers in different frames of reference. So someone in a different frame of reference could have measured my lifespan as more or less than I do.

 

 

So time in your conception depends on other frames of reference.

[Strange]

So time in your conception depends on other frames of reference.

 

No. I just wondered where relativity came into it.

[dad]

 

No. I just wondered where relativity came into it.

Me too.

[Phi for All]

What is time according to science or in reality? I don't think they really know, do they? Let's see.

 

Science has it's definitions and uses of the concept of time, but they often don't match up well with definitions others use. Mathematically, or in use with our coordinate system, time is part of equations we can use to quantify rates of change.

 

It's got different definitions and uses in philosophy and religion, so they don't interchange well. Thus they're a ripe target for the creationists who want to trap long-winded science-types in a semantic and circular argument.

[Mordred]

This gets complex, I'll try to keep it simple. You look at a clock at rest with yourself at rest.

 

Both you and the clock are in the same reference frame, you both being in the same gravitational potential and at rest.

 

Now if we add a third observer who is also looking at the same clock, but is moving, who also has a clock that has been previously synchronized with the other clock.

 

If the moving observer looks at the synchronized clock he is carrying he will see nothing unusual, however if he looks at the clock at rest, we will see it ticks at a different rate than the one he is carrying.

 

The observer at rest will measure the same change in the clock that is moving.

 

how you measure time depends on your reference frame (spacetime geometry) compared to the reference frame of the emitter.

 

There is essentially a couple of reasons this occurs.

 

light is the same velocity regardless of observer =c. So the velocity of measured signal (light pulses from the clock doesn't change)

 

When you have relativistic effects occur two key affects occur simultaneously. Time dilation and length contraction.

 

We model these two influences using time =ct. We map the spatial coordinates as x,y,Z. Hence 4d. Here time is treated coordinate with a vector component.

 

Collectively we refer to this as spacetime. Reference frames being the coordinate condition of the observer and the coordinate difference of the emitter compared to the observer.

 

if there is no difference in the coordinates the emitter and observer is in the same reference frame.

 

Reference frames apply at all scales of measure, locally and globally in the case of modelling spacetime geometry of the Universe.

 

As spacetime geometry also influences the light paths via null geodesics, we can essentially look for distortions in deep space images to measure potential spacetime geometry change. This is the function of the curvature term in the Cosmology FLRW metric, which is a simplified version of the Einstein field equations.

[Strange]

 

Let's say you are 40 years old. That time is due to relativity?

 

Perhaps the other practical definition of time is relevant here: "time is what clocks measure".

[dad]

 

Perhaps the other practical definition of time is relevant here: "time is what clocks measure".

 

Or maybe it is a real thing.

[Strange]

 

Or maybe it is a real thing.

 

Maybe. Depending what you mean by "real", "thing" and "time" (and maybe even "is").

 

Would you like to try defining your use of those terms in a precise way?

[Mordred]

The easiest way to think of time is the measured rate of change or duration. How we choose to model that rate can vary. Some models use "action" and geometry. GR uses geometry with vectors and scalars

Edited April 11, 2016 by Mordred

[dad]

This gets complex, I'll try to keep it simple. You look at a clock at rest with yourself at rest.

 

Both you and the clock are in the same reference frame, you both being in the same gravitational potential and at rest.

 

 

That doesn't work. What if time is independent of clocks and clocks just measure it?

 

Now if we add a third observer who is also looking at the same clock, but is moving, who also has a clock that has been previously synchronized with the other clock.

 

If the moving observer looks at the synchronized clock he is carrying he will see nothing unusual, however if he looks at the clock at rest, we will see it ticks at a different rate than the one he is carrying.

 

The observer at rest will measure the same change in the clock that is moving.

 

That is more like how time feels to observers and not what time itself is or isn't.

 

There is essentially a couple of reasons this occurs.

 

light is the same velocity regardless of observer =c.

 

 

Only if time exists. Otherwise we have no way of knowing velocity.

 

 

So the velocity of measured signal (light pulses from the clock doesn't change)

 

When you have relativistic effects occur two key affects occur simultaneously. Time dilation and length contraction.

 

 

How can one determine that is the case for stars? Yes in an airplane or satellite on earth it is...

 

We model these two influences using time =ct.

 

 

You can't do that. Not if t is supposed to be time.

 

Collectively we refer to this as spacetime. Reference frames being the coordinate condition of the observer and the coordinate difference of the emitter compared to the observer.

 

Excellent. That makes it clear spacetime tells us nothing about time existing, but is just a way to run imaginary lines.

 

if there is no difference in the coordinates the emitter and observer is in the same reference frame.

 

Not unless time and space exist in all coordinates.

 

Edited April 11, 2016 by dad

[Strange]

Please use the quote function properly. It is very hard to pick out your comments, and even harder to respond to them. Thank you.

[dad]

The easiest way to think of time is the measured rate of change or duration. How we choose to model that rate can vary. Some models use "action" and geometry. GR uses geometry with vectors and scalars

 

That is well and good for earth.

 

Maybe. Depending what you mean by "real", "thing" and "time" (and maybe even "is").

 

Would you like to try defining your use of those terms in a precise way?

 

Well, if time is like a force that exists, it would be a real force. Like gravity is real. Why think of it as merely something relative to observers?

 

As spacetime geometry also influences the light paths via null geodesics, we can essentially look for distortions in deep space images to measure potential spacetime geometry change. This is the function of the curvature term in the Cosmology FLRW metric, which is a simplified version of the Einstein field equations.

 

That assumes that curvature is caused by what you think. It also assumes that the curvature represents what you think.

[Mordred]

Quite frankly if time didn't exist neither would spacetime. The only way time cannot exist is if there is literally nothing, not even a volume.

 

In point of detail any absolutely empty volume would still have time.

Even if it never changes. That's a measure of duration.

 

Though quite frankly that's rather impossible to have a absolutely unchanging volume.

 

So the concept of no time is also a meaningless concept. Time also measures duration not just change.

 

Well, if time is like a force that exists, it would be a real force. Like gravity is real. Why think of it as merely something relative to observers?

 

 

That assumes that curvature is caused by what you think. It also assumes that the curvature represents what you think.

Time isn't a force it's a measurement.

 

It's not what I think, it's what GR allowed us to understand, and test.

 

The tests of GR is incredible, they have even measured the time dilation between your feet and your head.

 

It's used and tested everyday, for example particle accelerators and GPS satellites.

 

Any cosmological distance measurements employs GR. It must.

[dad]

Quite frankly if time didn't exist neither would spacetime. The only way time cannot exist is if there is literally nothing, not even a volume.

 

In point of detail any absolutely empty volume would still have time.

Even if it never changes. That's a measure of duration.

 

Though quite frankly that's rather impossible to have a absolutely unchanging volume.

 

So the concept of no time is also a meaningless concept. Time also measures duration not just change.

 

Time isn't a force it's a measurement.

 

It's not what I think, it's what GR allowed us to understand, and test.

 

The tests of GR is incredible, they have even measured the time dilation between your feet and your head.

 

You say time is not a force. So what we are supposed to swallow that by faith alone?

 

Of course time exists, so in OUR spacetime it exists in a certain blend, or mix or way.

Edited April 11, 2016 by dad

[Mordred]

It's not faith, look at the definition of time and then look at the definition of force.

 

This are basic physics terminology.

 

While looking at how force is defined study Newtons three laws of inertia.

 

If your going to argue against physics you may as well study basic physics terminology.

[Strange]

Well, if time is like a force that exists, it would be a real force. Like gravity is real. Why think of it as merely something relative to observers?

 

Do you have a mathematical model based on "time is like a force that exists"? If not, you are not talking about science.

[dad]

It's not faith, look at the definition of time and then look at the definition of force.

 

 

? Faith means believing without evidence and that is about the best definition for science that deals in origins.

 

Since I had a thread closed for a bogus reason, and was insulted by the mod in the process, I know I will be banned.

 

Here is a place one might discuss more freely..

 

http://www.christianforums.com/threads/what-is-time.7941706/

 

This are basic physics terminology.

 

While looking at how force is defined study Newtons three laws of inertia.

 

Who says it has to be a force IN physics? Think outside the box.

 

If your going to argue against physics you may as well study basic physics terminology.

 

Physics is fine in it's little place. Relax.

 

Do you have a mathematical model based on "time is like a force that exists"? If not, you are not talking about science.

To make a model one needs to have some grasp of what one has to work with. Science apparently doesn't meet that bar.

Edited April 11, 2016 by dad

[Mordred]

Lol our models do an incredible job of making predictions prior to observation.

If you wish to consider that based on faith so be it.

 

I have faith my feet is currently touching the floor.

 

In all seriousness though, I dont waste my time arguing belief.

If you want to discuss science that's fine. However if the counter argument you can come up with is to ignore scientific data of measurements and extremely well tested models with a lame poor argument of faith.

 

That conservation is far too boring of an argument. It lacks any imagination or scientific merit to discuss.

 

I honestly hope you can provide a better argument worth discussing other than "FAITH"