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  4. Would frame dragging cause the fabric of space to tear?
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Would frame dragging cause the fabric of space to tear?

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Offline talanum1 (OP)

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Would frame dragging cause the fabric of space to tear?
« on: 10/08/2020 12:25:22 »
I saw an animation of frame dragging. Seems to me that in such a situation space would eventually tear?
« Last Edit: 10/08/2020 16:58:39 by chris »
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Offline Janus

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #1 on: 10/08/2020 16:35:05 »
Quote from: talanum1 on 10/08/2020 12:25:22
I saw an animation of frame dragging. Seems to me that in such a situation space would eventually tear?
Space is not a material substance that can "tear".
If you meant a animation like this:
The "twisting" grid, are just visual references to  help show how the behavior of objects would differ with frame dragging.  so for example:  you would work out the orbit of the satellite at its distance from the planet relative to a "static" grid.   You would add any motion due to frame dragging at that distance in order to get the actual orbit.

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Offline Kryptid

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #2 on: 10/08/2020 21:02:17 »
Quote from: talanum1 on 10/08/2020 12:25:22
I saw an animation of frame dragging. Seems to me that in such a situation space would eventually tear?

Thankfully, no. I'm not entirely sure what it would mean for space to tear. What would be in the gaps between torn space? More space?

It might be better to think of frame dragging as the swirling of a liquid. No tearing involved. However, even the liquid analogy has its short-comings. A stationary object in a swirling liquid will feel a force pushing it in the direction of the flow. Such is not true of frame-dragging. An object will only feel a force from frame-dragging if it's moving relative to the central object that is rotating (akin to how magnetic induction works).
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Offline Jaaanosik

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #3 on: 11/08/2020 02:28:19 »
Frame dragging is part of the Special Relativity.



The platform observer at x=0cs, t=0s sends a light across, the blue arrow up, 90 degree up at the top part of the figure.
The train observer at x'=0cs', t'=0s' sends a light across, the red arrow up, 90 degree up at the top part of the figure.
This happens when they are aligned, x=x'=0 and t=t'=0.
Now frame dragging happens.
The red arrow up is frame dragged across the platform frame.
The red arrow up appears straight up for the train observer but as the blue arrow to the right from the platform x=0cs origin position.
The blue arrow up is frame dragged across the train frame in the reciprocal way.
The blue arrow up appears straight up for the platform observer but as the red arrow to the left from the train x'=0cs' origin position.
Simple, right?
Jano
« Last Edit: 11/08/2020 05:03:07 by Jaaanosik »
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Offline Kryptid

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #4 on: 11/08/2020 07:41:00 »
Quote from: Jaaanosik on 11/08/2020 02:28:19
Frame dragging is part of the Special Relativity.

No, frame dragging is a part of general relativity.

Quote from: Jaaanosik on 11/08/2020 02:28:19
The platform observer at x=0cs, t=0s sends a light across, the blue arrow up, 90 degree up at the top part of the figure.
The train observer at x'=0cs', t'=0s' sends a light across, the red arrow up, 90 degree up at the top part of the figure.
This happens when they are aligned, x=x'=0 and t=t'=0.
Now frame dragging happens.
The red arrow up is frame dragged across the platform frame.
The red arrow up appears straight up for the train observer but as the blue arrow to the right from the platform x=0cs origin position.
The blue arrow up is frame dragged across the train frame in the reciprocal way.
The blue arrow up appears straight up for the platform observer but as the red arrow to the left from the train x'=0cs' origin position.
Simple, right?
Jano

Why are you bringing this up here?
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Offline Jaaanosik

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #5 on: 11/08/2020 15:00:53 »
Quote from: Kryptid on 11/08/2020 07:41:00

No, frame dragging is a part of general relativity.

Why are you bringing this up here?

The frame dragging is part of the SR as per the figure.
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.
Adding the aberration to this scenario.
If the platform observer wanted to send his own light along the right red line then the platform observer has to shoot the platform beam under an angle. That's the aberration.
These are the facts, I am not saying anything that is not in line with the SR.
If I am then please, show me,
Jano
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Offline Kryptid

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #6 on: 11/08/2020 20:34:08 »
Quote from: Jaaanosik on 11/08/2020 15:00:53
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.

What do you think frame dragging is, exactly?
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Offline Janus

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #7 on: 11/08/2020 20:57:15 »
Quote from: Jaaanosik on 11/08/2020 15:00:53
Quote from: Kryptid on 11/08/2020 07:41:00

No, frame dragging is a part of general relativity.

Why are you bringing this up here?

The frame dragging is part of the SR as per the figure.
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.
Adding the aberration to this scenario.
If the platform observer wanted to send his own light along the right red line then the platform observer has to shoot the platform beam under an angle. That's the aberration.
These are the facts, I am not saying anything that is not in line with the SR.
If I am then please, show me,
Jano
This is not frame dragging. This is just how the path of the light is judged as being as measured from different inertial frames.
Frame dragging is something totally different.  To illustrate the difference, imagine the following scenario:
You have two observers above the pole of a rotating planet. One is inertial and the other shares the planet's rotation.    A light beam comes in along the plane of Planet's equator.
First we will assume no frame dragging.  From the inertial observer's frame the light comes in on a straight line until it hits the planet's equator.  From the rotating observers frame, the light appears to follow a curved path. Again this is just due to the observations being made from different frames.
Now we add in frame dragging.  The mass of the rotating planet adds a new factor to the space-time curvature.  Now the Inertial observer will observe that the light follows a slight curve rather than a straight line, much like the rotating planet is trying to "drag" the light along with its rotation. 
The rotating observer would note this too, but for him this "curve" is opposite to the curve he would have measured in the earlier example, so this results in his measuring slightly less of a curve in the light's path than he would without frame dragging.

Normally, frame dragging is a very weak effect.  An exception to this is near black holes.  With a rotating black hole, there can be a region ( the ergosphere) where the frame dragging is so strong that objects orbiting the black hole can only orbit in the same direction as the BH rotates.
« Last Edit: 11/08/2020 21:02:37 by Janus »
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Offline Jaaanosik

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #8 on: 11/08/2020 20:58:19 »
Quote from: Kryptid on 11/08/2020 20:34:08
Quote from: Jaaanosik on 11/08/2020 15:00:53
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.

What do you think frame dragging is, exactly?
When motion in the first frame affects the motions (conclusions about the motion) in the other frame.
That is almost as simple explanation as possible, how GR frame dragging works, isn't?
Jano
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Offline Jaaanosik

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #9 on: 11/08/2020 21:18:16 »
Quote from: Janus on 11/08/2020 20:57:15
Quote from: Jaaanosik on 11/08/2020 15:00:53
Quote from: Kryptid on 11/08/2020 07:41:00

No, frame dragging is a part of general relativity.

Why are you bringing this up here?

The frame dragging is part of the SR as per the figure.
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.
Adding the aberration to this scenario.
If the platform observer wanted to send his own light along the right red line then the platform observer has to shoot the platform beam under an angle. That's the aberration.
These are the facts, I am not saying anything that is not in line with the SR.
If I am then please, show me,
Jano
This is not frame dragging. This is just how the path of the light is judged as being as measured from different inertial frames.
Frame dragging is something totally different.  To illustrate the difference, imagine the following scenario:
You have two observers above the pole of a rotating planet. One is inertial and the other shares the planet's rotation.    A light beam comes in along the plane of Planet's equator.
First we will assume no frame dragging.  From the inertial observer's frame the light comes in on a straight line until it hits the planet's equator.  From the rotating observers frame, the light appears to follow a curved path. Again this is just due to the observations being made from different frames.
Now we add in frame dragging.  The mass of the rotating planet adds a new factor to the space-time curvature.  Now the Inertial observer will observe that the light follows a slight curve rather than a straight line, much like the rotating planet is trying to "drag" the light along with its rotation. 
The rotating observer would note this too, but for him this "curve" is opposite to the curve he would have measured in the earlier example, so this results in his measuring slightly less of a curve in the light's path than he would without frame dragging.

Normally, frame dragging is a very weak effect.  An exception to this is near black holes.  With a rotating black hole, there can be a region ( the ergosphere) where the frame dragging is so strong that objects orbiting the black hole can only orbit in the same direction as the BH rotates.

It appears to me you switched the observers, who sees the light straight, no big deal.
Imaging two boys throwing a tennis ball across a moving train car.
Now they are doing the same thing on a moving open flatbed train car.
They throw the ball 90 degrees to the train velocity in the closed train car but under an angle on the open flatbed to account for the aberration.
So this is not frame dragging?
The tennis ball is not frame dragged inside the train car from the outside point of view?
I do not want to talk about light medium, just to point out that the observation about the light propagation appears to be similar to the one with the tennis balls.
Jano
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Offline Kryptid

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #10 on: 11/08/2020 22:11:55 »
Quote from: Jaaanosik on 11/08/2020 20:58:19
When motion in the first frame affects the motions (conclusions about the motion) in the other frame.

No, that is not frame-dragging. This is what frame-dragging is:
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Offline Jaaanosik

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #11 on: 11/08/2020 23:02:46 »
The platform observer sees:

c^2 = (c/2)^2 + v^2

The y axis is not contracted but the light crosses the y direction at different speeds for different observers.
The light crosses the y direction at c for the train observer.
The light crosses the y direction at c/2 for the platform observer.

Here is a quote from https://en.wikipedia.org/wiki/Aberration_(astronomy)#Explanation
Quote
While classical reasoning gives intuition for aberration, it leads to a number of physical paradoxes observable even at the classical level (see history). The theory of special relativity is required to correctly account for aberration. The relativistic explanation is very similar to the classical one however, and in both theories aberration may be understood as a case of addition of velocities. While classical reasoning gives intuition for aberration, it leads to a number of physical paradoxes observable even at the classical level (see history). The theory of special relativity is required to correctly account for aberration. The relativistic explanation is very similar to the classical one however, and in both theories aberration may be understood as a case of addition of velocities.

The last sentence: "... in both theories aberration may be understood as a case of addition of velocities."
Why the classical addition of the velocities and the NOT relativity addition???
c^2 = (c/2)^2 + v^2
Why do we consider 90 degrees from the train frame in the platform frame?
Why do we mix frames?
If we do not acknowledge the frame dragging then we do not have 90 degrees.
We do not have a classical addition of the velocities.
If we say that frame dragging does not happen then we need to take out v^2 from the velocity addition and we would get c!=c.
Jano
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Offline Kryptid

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #12 on: 11/08/2020 23:12:34 »
Quote from: Jaaanosik on 11/08/2020 23:02:46
The platform observer sees:

c^2 = (c/2)^2 + v^2

The y axis is not contracted but the light crosses the y direction at different speeds for different observers.
The light crosses the y direction at c for the train observer.
The light crosses the y direction at c/2 for the platform observer.

Here is a quote from https://en.wikipedia.org/wiki/Aberration_(astronomy)#Explanation
Quote
While classical reasoning gives intuition for aberration, it leads to a number of physical paradoxes observable even at the classical level (see history). The theory of special relativity is required to correctly account for aberration. The relativistic explanation is very similar to the classical one however, and in both theories aberration may be understood as a case of addition of velocities. While classical reasoning gives intuition for aberration, it leads to a number of physical paradoxes observable even at the classical level (see history). The theory of special relativity is required to correctly account for aberration. The relativistic explanation is very similar to the classical one however, and in both theories aberration may be understood as a case of addition of velocities.

The last sentence: "... in both theories aberration may be understood as a case of addition of velocities."
Why the classical addition of the velocities and the NOT relativity addition???
c^2 = (c/2)^2 + v^2
Why do we consider 90 degrees from the train frame in the platform frame?
Why do we mix frames?
If we do not acknowledge the frame dragging then we do not have 90 degrees.
We do not have a classical addition of the velocities.
If we say that frame dragging does not happen then we need to take out v^2 from the velocity addition and we would get c!=c.
Jano

For the last time, what you are talking about is not frame-dragging. Did you even watch the video I posted?
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Offline Janus

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #13 on: 11/08/2020 23:36:24 »
Quote from: Jaaanosik on 11/08/2020 21:18:16
Quote from: Janus on 11/08/2020 20:57:15
Quote from: Jaaanosik on 11/08/2020 15:00:53
Quote from: Kryptid on 11/08/2020 07:41:00

No, frame dragging is a part of general relativity.

Why are you bringing this up here?

The frame dragging is part of the SR as per the figure.
The red arrow up stays 90 degree up in the train frame because it is dragged with the train frame from the platform point of view.
This is the fact.
Adding the aberration to this scenario.
If the platform observer wanted to send his own light along the right red line then the platform observer has to shoot the platform beam under an angle. That's the aberration.
These are the facts, I am not saying anything that is not in line with the SR.
If I am then please, show me,
Jano
This is not frame dragging. This is just how the path of the light is judged as being as measured from different inertial frames.
Frame dragging is something totally different.  To illustrate the difference, imagine the following scenario:
You have two observers above the pole of a rotating planet. One is inertial and the other shares the planet's rotation.    A light beam comes in along the plane of Planet's equator.
First we will assume no frame dragging.  From the inertial observer's frame the light comes in on a straight line until it hits the planet's equator.  From the rotating observers frame, the light appears to follow a curved path. Again this is just due to the observations being made from different frames.
Now we add in frame dragging.  The mass of the rotating planet adds a new factor to the space-time curvature.  Now the Inertial observer will observe that the light follows a slight curve rather than a straight line, much like the rotating planet is trying to "drag" the light along with its rotation. 
The rotating observer would note this too, but for him this "curve" is opposite to the curve he would have measured in the earlier example, so this results in his measuring slightly less of a curve in the light's path than he would without frame dragging.

Normally, frame dragging is a very weak effect.  An exception to this is near black holes.  With a rotating black hole, there can be a region ( the ergosphere) where the frame dragging is so strong that objects orbiting the black hole can only orbit in the same direction as the BH rotates.

It appears to me you switched the observers, who sees the light straight, no big deal.
Imaging two boys throwing a tennis ball across a moving train car.
Now they are doing the same thing on a moving open flatbed train car.
They throw the ball 90 degrees to the train velocity in the closed train car but under an angle on the open flatbed to account for the aberration.
So this is not frame dragging?
The tennis ball is not frame dragged inside the train car from the outside point of view?
I do not want to talk about light medium, just to point out that the observation about the light propagation appears to be similar to the one with the tennis balls.
Jano

As Kryptid has also said, No, this is not frame dragging.  Frame dragging is a GR effect that involves a rotating mass.
It has has nothing to do with your example.  In fact, your example isn't even a good one for aberration.
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Offline evan_au

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #14 on: 13/08/2020 12:06:16 »
Quote from: OP
Would frame dragging cause the fabric of space to tear?
The most dramatic example of frame dragging is around a black hole with a large angular momentum.

Could a rapidly rotating black hole "spaghettify" you faster than a non-rotating black hole of the same mass?

So frame dragging may not tear space, but it might be able to tear a fragile human body (a few microseconds sooner...).
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Offline Jarek Duda

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    • http://th.if.uj.edu.pl/~dudaj/
Re: Would frame dragging cause the fabric of space to tear?
« Reply #15 on: 17/08/2020 16:27:51 »
Frame draging has also electromagnetic and hydrodynamical analogues, generally corresponding to rotation (magnetic field as vorticity) - nothing to tear here.
Nice diagrams from https://en.wikipedia.org/wiki/Gravitoelectromagnetism

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Offline yor_on

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Re: Would frame dragging cause the fabric of space to tear?
« Reply #16 on: 04/09/2020 14:52:25 »
That one was funny :)

I had this proposition once, that perforated toilet paper refuse to tear where it should, at the perforations. The perforations consisting of a 'nothing', aka holes.

How do you get 'nothing' to tear?
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