Exploring Frame Dragging & Its Impact on Space: Q&A

The more spin it has, the more it drags space around with it. This is frame-dragging.In summary, the conversation discusses questions about space, inertia, and frame-dragging. The speaker is unable to find intuitive explanations for these phenomena and is seeking answers on a conceptual level. The questions cover topics such as the Lense-Thirring effect, the rotational drag of space around large objects, linear frame-dragging, and the relationship between mass and the rotation of space. The conversation also mentions Einstein's thoughts on inertia and how they relate to the concept of space being dragged by accelerating mass-energy currents. The conversation concludes with a discussion on the rejection of Machian explanations for inertia and the possibility of space itself having
  • #1
e2m2a
354
11
I have some questions about space, inertia and frame-dragging that I can’t find anywhere on the internet. The papers that I have found that deal with the subject are often couched in advanced mathematics, so that I can’t get an intuitive grasp of the phenomenon.

I would appreciate if someone could answer on a conceptual level some of the questions I have on the subject.

Question set one: Lense-Thirring rotational frame-dragging. The results of the Gravity probe B experiment suggested very strongly that this effect is real. I kind of get that the spinning Earth drags space along with it. But is it the space itself, because it is being dragged, actually has a physical effect on the gyroscopes, causing real torques on the gyroscopes, which causes them to experience precession? Put another way, is space “colliding” with the gyroscopes?

Question set two: I understand the rotational drag effect of space around the Earth is incredibly small, such as once in centuries. But in the case of an intense gravitational object, such as a black hole, does this rate of rotation of space equal the rate of the rotating black hole? Another words, is the rate of rotation of space around a rotating body proportional to the mass of the rotating body?

Question set three: Linear frame dragging. On page 106, The Meaning of Relativity, Einstein reflecting on inertia wrote:

But in the second place, the theory of relativity makes it

appear probable that Mach was on the right road in his thought

that inertia depends upon a mutual action of matter. For we

shall show in the following that, according to our equations, inert

masses do act upon each other in the sense of the relativity of

inertia, even if only very feebly. What is to be expected along

the line of Mach's thought?

1. The inertia of a body must increase when ponderable

masses are piled up in its neighbourhood.

2. A body must experience an accelerating force when

neighbouring masses are accelerated, and, in fact, the

force must be in the same direction as the acceleration.

3. A rotating hollow body must generate inside of itself

a \Coriolis _eld," which deects moving bodies in the

sense of the rotation, and a radial centrifugal _eld as

well.

My question pertains to the second point. Was Einstein conjecturing that linear inertial reaction forces arise when there is relative linear acceleration with respect to cosmic mass-energy currents? And was he implying that it is space itself that is being dragged by the accelerating mass-energy currents, and therefore, it is the “accelerating” space that is causing real effects(inertial forces) on test mass objects?

Question set four: My understanding Einstein later rejected Machian explanations as a cause of inertia because it was found that his field equations predict that inertial forces can still exist in a universe empty of mass. But could this rejection been premature? Again, is it possible that space itself has intrinsic properties such that when there is relative acceleration between space and an object, that space itself can “collide” with the object, causing real, physical effects on the object?
 
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  • #2
e2m2a said:
But is it the space itself, because it is being dragged, actually has a physical effect on the gyroscopes, causing real torques on the gyroscopes, which causes them to experience precession?

The word "precession" as it's used in this context is somewhat misleading, because the gyroscopes in Gravity Probe B, which confirmed the Lense-Thirring effect, are not being subjected to any torques at all. The "precession" a gyroscope undergoes as it orbits a massive body like the Earth is really a comparison between where its axis actually points, vs. where its axis would be expected to point if pure Newtonian physics were true--i.e., if the axis of the gyroscope were really "fixed in space", always pointing in the exact same direction, when no torques were acting on it. In other words, "precession" of a gyroscope in relativity occurs in the absence of any torques at all.

e2m2a said:
is the rate of rotation of space around a rotating body proportional to the mass of the rotating body?

No, it's proportional to its angular momentum.
 

Related to Exploring Frame Dragging & Its Impact on Space: Q&A

1. What is frame dragging?

Frame dragging, also known as the Lense-Thirring effect, is a phenomenon in which the rotation of a massive object, such as a planet or a star, causes the spacetime around it to twist and drag along with it.

2. How does frame dragging impact space?

Frame dragging can have a significant impact on space, particularly on the motion of other objects around the rotating mass. It can cause the orbits of nearby objects to precess, or shift, in the direction of the rotation. It can also affect the paths of light and other forms of radiation.

3. What is the evidence for frame dragging?

One of the most famous pieces of evidence for frame dragging is the Gravity Probe B experiment conducted by NASA. This experiment measured the geodetic and frame-dragging effects of Earth's rotation on the orbits of four gyroscopes in a satellite. The results were consistent with Einstein's theory of general relativity and confirmed the existence of frame dragging.

4. How does frame dragging impact the study of black holes?

Frame dragging plays a crucial role in our understanding of black holes. It is believed that frame dragging is responsible for the formation of the accretion disk around a black hole and the jets of matter that are ejected from its poles. It also affects the motion of matter and light near the event horizon, influencing how we observe and study these elusive objects.

5. Can frame dragging be observed in everyday life?

Frame dragging is a subtle effect and is not observable in our everyday lives. It requires massive and rapidly rotating objects, such as planets and stars, to produce a measurable effect. However, its impact on space and our understanding of the universe is significant and continues to be studied by scientists.

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