Time Gravity

[Bird11dog]

I am referring to the possibility that time dilation is the mechanism by which we see not only gravity but also inertia. A metaphoric experiment if you will that describes this mechanism.

 

Suppose we had a kiddie train track 100 m long. We place a student school desk that has track wheels attached to it on the track. We attach a digital timer to the desk and of course a drive mechanism that can maintain a constant velocity. On the track we place two switches that are some distance apart. The first turns the digital timer on and the second turns it off. We put a student in the desk and tell him how far apart the switches are and the total mass of his system. We ask the student to calculate his momentum at the end of the run. The desk will have a constant velocity. At the end of the run he gives us a value for his momentum. We move the desk back to the starting point in order to do another run. Unbeknownst to the student I can remotely control the timer. I reduce the rate of the timer by 10% and start the run again. At the end of the run we ask the student which run had the greatest momentum and of course he says the second. Isn't this situation somewhat like a rock sitting on the surface of the earth. The atoms of the rock are vibrating around and colliding with other atoms fields and the atoms clocks are speeding up and slowing down ever so slightly so that the collective momentum of the atoms points to the center of the earth?

Now look at one mole of any element sitting at the surface of the Earth. Now imagine the atoms of the element traveling back-and-forth on trillions of our little kiddie train tracks, Their tiny clocks speeding up and slowing down as they move up and down in the gravity well. I do not possess the mathematical skills to test this hypothesis but using Avogadro's number it should be possible to calculate the weight of one mole which should be equal to the mass of one mole. As for inertia, if you take the same one mole far out into space where there is very little gravity and give it a one gee acceleration the the atoms clocks do just as they did on Earth with the momentum being opposite the direction of acceleration, hence inertia.

[md65536]

If a particle is oscillating side-to-side it wouldn't be moving up and down the gravity well. Yet, particles seem to accelerate at the same rate regardless of how they're oriented. How would you account for that?

[Bird11dog]

You're right, side to side they wouldn't be but the total acceleration would be in the down direction. As far as your second question I don't know how you would measure the acceleration of a particle inside a rock so I don't see the purpose of your second question.

[Bird11dog]

Gr says that matter warps space/time. We have proof that matter warps time but do we have proof that matter warps space?

[Mordred]

Length contraction

[swansont]

Gr says that matter warps space/time. We have proof that matter warps time but do we have proof that matter warps space?

Gravitational lensing.

[Bird11dog]

Length contraction

This is dependent upon your frame of reference so I wouldn't really call that proof.

Gravitational lensing.

This could be construed as proof but could it not be caused by something else such as time dilation?

[Mordred]

Both time dilation and length contraction are needed to cause gravitational lensing.

[MigL]

The procession of Mercury's orbit is usually explained in terms of space warping close to a massive gravitating body.

[swansont]

This could be construed as proof but could it not be caused by something else such as time dilation?

How would time dilation alone change the direction of light?

[Bird11dog]

Because time dilation shortens the done going side of the wave.

[swansont]

Because time dilation shortens the done going side of the wave.

 

 

"Down-going" (I assume) side of the wave? What side is that?

[Bird11dog]

The photon is a sine wave, right?

[swansont]

The photon is a sine wave, right?

 

The strength of the E and B fields of a classical EM wave of a single frequency is a sine wave. "The photon is a sine wave" is actually a pretty meaningless statement.

[Bird11dog]

That is true because a photon could be half of a sine wave.

[swansont]

That is true because a photon could be half of a sine wave.

 

 

That's just as meaningless.

[machapungo]

Gr says that matter warps space/time. We have proof that matter warps time but do we have proof that matter warps space?

How can matter warp time if time is not a physical part of the universe. Everything that exists is a form of energy, even space.

Where is the evidence that time is energy? Time, IMO, is just a mental invention to measure and explain motion by using relative motion.

[Strange]

How can matter warp time if time is not a physical part of the universe. Everything that exists is a form of energy, even space.

Where is the evidence that time is energy? Time, IMO, is just a mental invention to measure and explain motion by using relative motion.

 

 

Not everything is a form of energy. Space is not energy (it may contain energy, though). Space is just the distance between things. Time is also another measure of the distance between things. In order to meet someone you need to specify both a location (3 dimensions) and a time (the 4th dimension).

 

The geometry of both space and time are changed by the presence of mass or energy. That is what causes the effect we perceive as gravity (which is mainly due to the curvature of the time dimension).

 

p.s. Sorry but I hit the "down vote" button when aiming for the Quote button. Maybe someone else will kindly remove that negative vote....

EDIT: Thank you!

Edited April 10, 2017 by Strange

[machapungo]

 

 

Not everything is a form of energy. Space is not energy (it may contain energy, though). Space is just the distance between things. Time is also another measure of the distance between things. In order to meet someone you need to specify both a location (3 dimensions) and a time (the 4th dimension).

 

The geometry of both space and time are changed by the presence of mass or energy. That is what causes the effect we perceive as gravity (which is mainly due to the curvature of the time dimension).

 

p.s. Sorry but I hit the "down vote" button when aiming for the Quote button. Maybe someone else will kindly remove that negative vote....

EDIT: Thank you!

Hello Strange,

You say "space is not energy but it MAY contain energy". I do not think this point of view is supported by the legitimate physics community. You speak of space and time as "just being a measure of the distance between things". All measurements are a product of the mind. Measurements are not a physical thing. The universe, itself, can exist just fine without our measurements. Your reference to meeting some one at a specific time and place as if these were properties of the universe. They are not. They are concepts of the human mind.

You are falling into the trap of mixing the attributes of the observer with the observed. You speak of geometry. Again, geometry is a product of the mind that is intended to help us understand the physical universe but should not be confused with the actual physical universe. All of our understandings are abstractions of physical reality.

 

All of our input is a function of our five senses. All of our senses involve a transformation of the data via different means of transmission and their inherent delays. Consequently, all data that enters the mind is old and does not represent the EXACT state of the current (NOW) of the universe which is in the constant flux of the continuum of motion at many levels of existence. The data input to the mind suffers additional delays to reach our consciousness and make it's way through our analysis. What this means is that we have no conscious DIRECT CONTACT with the reality of the constantly changing universe. We have no direct mental contact with the NOW, In effect, all of our thoughts are based on a past state of the entire universe, or a portion thereof, that has changed, at least in some small way at the moment we finally perceive it.

 

You did not address my assertion that time is not a physical reality. You quote an idea that gravity is mainly due to the curvature on the time dimension as if it were a physical thing. There is no apparatus or test that has ever shown that time is a physical reality. All we have are our brains and our clocks that are either natural in origin or of one human design or another. All they do is measure motion of something else relative to their own motion. Let's examine the experiment that takes two identical and synchronized atomic clocks and puts one on on an airplane and leaves the other on the surface of the planet. After the plane takes a trip they determine that the two clocks offer slightly different readings of the time that has passed since the beginning of the test. All this really shows, is that the motion of the entire clock affects the physics of the components of the clock and not the passage of some mythical non physical time. Likewise, with the affect of gravity on the clock based passage of time. The people that accept that these tests as showing something about time are chasing the myth that time is somehow physical. Motion is real and motion at one level can affect motion at another just as gravity, which is real, can also affect motion. They need to focus on motion itself, and yes their main tools in this endeavor is the clock and their brains. Regards.

[Strange]

Hello Strange,

You say "space is not energy but it MAY contain energy". I do not think this point of view is supported by the legitimate physics community.

 

 

As I was summarising the description provided by GR, I think most physicists would agree (although we all know it is incomplete).

 

 

 

You speak of space and time as "just being a measure of the distance between things". All measurements are a product of the mind. Measurements are not a physical thing.

 

This, and most of the rest of your post, are good points about the nature of reality and the relationship to mind. But it is off topic. You might want to post this in the Philosophy section of the forum.

 

 

 

There is no apparatus or test that has ever shown that time is a physical reality.

 

That would be the clock. Note that all of your comments about time are equally applicable to length or distance.

 

But science creates models and makes measurements to test those models. You can argue about what is "really" being measured (if anything) but that has little to do with science.

[swansont]

Hello Strange,

You say "space is not energy but it MAY contain energy". I do not think this point of view is supported by the legitimate physics community.

Pretty sure it is.

 

You speak of space and time as "just being a measure of the distance between things". All measurements are a product of the mind. Measurements are not a physical thing. The universe, itself, can exist just fine without our measurements. Your reference to meeting some one at a specific time and place as if these were properties of the universe. They are not. They are concepts of the human mind.

There's a lot of physics that is conceptual rather than physically existing. Mainstream physics does not claim that time is a substance, or a force, or energy.

 

You did not address my assertion that time is not a physical reality.

I'm not sure what definition of "physical reality" you are using.

 

You quote an idea that gravity is mainly due to the curvature on the time dimension as if it were a physical thing. There is no apparatus or test that has ever shown that time is a physical reality. All we have are our brains and our clocks that are either natural in origin or of one human design or another. All they do is measure motion of something else relative to their own motion. Let's examine the experiment that takes two identical and synchronized atomic clocks and puts one on on an airplane and leaves the other on the surface of the planet. After the plane takes a trip they determine that the two clocks offer slightly different readings of the time that has passed since the beginning of the test. All this really shows, is that the motion of the entire clock affects the physics of the components of the clock and not the passage of some mythical non physical time. Likewise, with the affect of gravity on the clock based passage of time. The people that accept that these tests as showing something about time are chasing the myth that time is somehow physical. Motion is real and motion at one level can affect motion at another just as gravity, which is real, can also affect motion. They need to focus on motion itself, and yes their main tools in this endeavor is the clock and their brains. Regards.

In QM motion is fuzzy concept — an electron, for example, does not have a well-defined trajectory in an atom, so discussing its motion is problematic. The best atomic clocks and frequency standards today try and reduce the center-of-mass motion of the atoms as much as possible, because it makes the measurement worse.

 

Moving clocks run slow. It doesn't matter what kind of clock it is. And anything moving at a constant velocity doesn't "know" that it's moving. Any claim that the motion is causing a physical effect will require some new physics.

[Howard Landman]

The gravity that we (as slow moving objects) experience here one the Earth (far away from any black holes) is almost entirely due to "curvature of time", i.e. the time dilation field around the Earth. The easiest way to see this is to assume a spherical non-rotating Earth, so we can use the Schwarzschild metric:

ds² = -(1 - 2GM/r)c²dt² + (1 - 2GM/r)^-1dr² + r²dΩ²

In the weak-field limit where GM/r is small (i.e. far from any black holes, r >> r_s = 2GM/c²) this is approximately:

ds² = -c²dt² + (1 - 2GM/r)^-1dr² + r²dΩ² + (2GM/r)c²dt² + (2GM/r)dr²

The 2nd and 3rd terms together are just dx² + dy² + dz² (in polar coordinates); they give the length of flat Euclidean space. The first 3 terms together give flat Minkowski spacetime, which has no gravity. For particles that are slow (v = dr/dt << c), dr << cdt so we can ignore the last term which corresponds to the space curvature, and get simply:

ds² = -c²dt² + (1 - 2GM/r)^-1dr² + r²dΩ² + (2GM/r)c²dt² = flat_spacetime + time_dilation

This tells us that space is extremely flat near the Earth, and almost ALL the gravity is coming from the time term, which merely describes the time dilation field. In fact the geodesics of this metric give Newtonian gravity; note that GM/r = Φ(r) = the Newtonian gravitational potential. "The reason that your ass is being pressed into your seat is that time is moving faster at your head than at your feet." - Landman's Mantra

(As a curious aside, chapter 12 of Misner-Thorne-Wheeler Gravitation states that it is IMPOSSIBLE to have a metric for Newtonian gravity, but their proof makes assumptions that don't apply to this metric, so their conclusion is false despite the fact that the proof is perfectly valid. See their Exercise 12.10 for more details.)

Swansont Bird11dog asks "do we have proof that matter warps space?" Yes we do. The bending of light by the Sun is twice as great as predicted by Newtonian gravity. The time dilation term gives the Newtonian prediction, and the other half comes from the space term which we ignored for slow-moving objects. Light is not slow-moving, so we can't ignore that term for light. To light, time and space appear about equally curved by the Sun. GR also predicts that space will be severely warped near a black hole event horizon, but we may need to wait a few years before we can test that directly. In the mean time, gravitational waves might tell us something.

Swansont Bird11dog  also asks how time can bend light. The effect is similar to a graded index of refraction (GRIN) lens. If time is flowing faster at the top than at the bottom of a wave packet moving right, then then the speed of light is different, and a wave packet that starts out like ||||||||||| will eventually start to look like /////////// and the packet will be traveling slightly downward.

Machapungo complains that "[nothing] has ever shown that time is a physical reality", but certainly many experiments have shown that time dilation is a physical reality, so I'm not sure what his point is. It's kind of like quantum phase; absolute phase may or may not be real, but phase frequency = energy and certainly is real. Similarly, absolute time is probably meaningless since you can set T₀ to be anywhere you want; but the passage of time is demonstrably real and measurable.

Edited November 7, 2018 by Strange
correct attributions

[swansont]

46 minutes ago, Howard Landman said:

 

Swansont asks "do we have proof that matter warps space?" 

No, he didn't

 

[Howard Landman]

Oops, sorry, I see that it was actually Bird11dog. How do I edit to fix that? There doesn't seem to be any edit button. Also I apparently neglected to remove some terms from the later equations ... typical "copy paste and forget to change" error. The last 2 should be

ds² = -c²dt² + dr² + r²dΩ² + (2GM/r)c²dt² + (2GM/r)dr² 

and

ds² = -c²dt² + dr² + r²dΩ² + (2GM/r)c²dt²

respectively.

Edited November 7, 2018 by Howard Landman
Explaining what edits I would be making if I could.

[Strange]

17 minutes ago, Howard Landman said:

Oops, sorry, I see that it was actually Bird11dog. How do I edit to fix that?

I have done it for you (the forum only allows you a limited time to edit posts).