Ik heb chatgtp gevraagd of als je twee raketten vertikaal lanceert en ze blijven vertikaal gaan je kan concluderen dat de planeet dan niet draait. Oftewel rotatie is niet relatief. Ik vermoed dat deze conclusie onjuist is maar waar ? ;-) 

Hieronder de conversatie, negeer mijn spelfouten aub.

phiscs question. Imagine a empty universe(no reference points) and the observer stands on a earthsize planet. He fires a rocket straight up. he can see thetrajectory the rocket is taking. Does this trajectory tell the observer wheter or not the plannet is spinning ?
 
ChatGPT said:
ChatGPT
In an empty universe with no external reference points, the trajectory of the rocket alone does not directly reveal whether the planet is spinning. Here’s why:

Lack of External Reference Points: In an empty universe with no stars, planets, or any other objects, the observer has no external reference points to compare motion against. The concept of "spinning" usually requires comparing the planet's rotation relative to something else.
Newton's First Law of Motion (Inertia): If the planet is spinning, the rocket might be affected by the Coriolis effect, which could cause its trajectory to curve relative to the surface of the planet. However, in the absence of any external reference points, this curve would be the only clue. The observer might notice that the rocket doesn’t follow a perfectly straight path (relative to the surface of the planet), but they might not immediately conclude that this is due to the planet spinning. They might attribute it to other factors, like a force acting on the rocket.
Coriolis Effect: If the observer is aware of the Coriolis effect, they might infer the planet's rotation based on the observed deviation of the rocket's trajectory from a straight line. For example, on Earth, the Coriolis effect causes projectiles to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. If the observer notices a consistent deviation in one direction, they could infer that the planet is spinning.
Relative Motion: The observer might also consider the relative motion between the planet and the rocket. If they observe a consistent deviation in the rocket’s trajectory, they could hypothesize that the planet is rotating. However, without external reference points, this is challenging to determine definitively.
Conclusion: While the trajectory might provide some clues, the observer would need to understand the Coriolis effect and apply that knowledge to infer the planet's rotation. The trajectory alone, in the absence of reference points, doesn't directly or obviously reveal the planet’s spin. The observer's ability to interpret the trajectory as evidence of the planet's spinning depends on their understanding of physics and the behavior of objects on rotating bodies.
 
 
4o

 
You said:
Suppose the observer sees the rocket go straight up. Can he then conclude the planet is not spinning?
 
ChatGPT said:
ChatGPT
If the observer sees the rocket go straight up and it follows a perfectly vertical trajectory with no horizontal deviation, they might be tempted to conclude that the planet is not spinning. However, this conclusion isn't necessarily definitive due to a few key considerations:

Rocket Launch Conditions: The rocket might have been launched in a way that compensates for any Coriolis effect or horizontal forces, making its trajectory appear perfectly vertical even if the planet is spinning.
Location on the Planet: The observer's location on the planet matters. At the poles of a spinning planet, a rocket launched straight up would indeed move straight up relative to the surface because the Coriolis effect is minimal or nonexistent at the poles. At the equator, however, the Coriolis effect would be more pronounced, and any spin of the planet would likely cause some horizontal deviation in the rocket's path.
Detectability of Coriolis Effect: The Coriolis effect on a small scale might be very subtle. If the rocket is observed over a short duration or a small distance, the horizontal deviation might be too small to detect, especially in the absence of external reference points.
Conclusion:
If the rocket goes straight up and there is no observed horizontal deviation in its trajectory, the observer might reasonably infer that the planet is not spinning, particularly if they are aware of how the Coriolis effect would manifest on a rotating planet. However, this inference is not ironclad. The absence of observed deviation could be due to factors such as the observer's location (e.g., at the poles) or the precision of the launch, rather than a lack of planetary spin.
 
 
4o

 
You said:
So suppose we launch 2 rockets from slighttly different locations to curcomvent the possibility that 1 launch site is on a pole and still all trajectories are perfectly vertical
 
ChatGPT said:
ChatGPT
If two rockets are launched from slightly different locations on the planet, and both trajectories are observed to be perfectly vertical (with no horizontal deviation) relative to the surface of the planet, the observer could indeed draw a stronger conclusion about the rotation of the planet. Here’s how:

Considerations:
Coriolis Effect: On a rotating planet, the Coriolis effect would typically cause the trajectories of the rockets to deviate slightly in opposite directions if they were launched from different locations. For example, if one rocket is launched from a location slightly north of the other, their paths should curve in different directions due to the varying effects of the planet’s rotation.
Location of Launch Sites: The observer’s conclusion becomes more robust if the two launch sites are not at the poles and are separated by a significant distance (but still within the observer’s ability to see the trajectories clearly). On a rotating planet, the further apart the launch sites, the more noticeable the differences in trajectory should be due to the Coriolis effect.
Conclusion:
If the observer sees that both rockets, launched from slightly different locations, follow perfectly vertical trajectories with no horizontal deviation, it strongly suggests that the planet is not spinning. This is because, on a rotating planet, the Coriolis effect would typically cause some deviation in the rocket's trajectory, and this effect should differ between the two launch sites.

Thus, observing perfectly vertical trajectories for both rockets, regardless of their launch locations, provides strong evidence that the planet is not rotating.
 
 
4o

 
You said:
Is it then reasonable to divide objects in the universe in two groups : rotating and not rotating ?
 
ChatGPT said:
ChatGPT
Dividing objects in the universe into two distinct groups—rotating and not rotating—is a useful conceptual framework, but it comes with important caveats:

1. Relative Nature of Rotation:
Rotation Relative to What?: Rotation is typically defined relative to a particular reference frame. In the universe, there's no absolute reference frame, so whether an object is considered rotating depends on the frame of reference you choose.
Inertial vs. Non-Inertial Frames: In an inertial frame (one that is not accelerating), an object can be classified as rotating if it has a non-zero angular velocity. In a non-inertial (accelerating) frame, even objects that appear non-rotating could exhibit apparent rotational effects.
2. Measurement of Rotation:
Observability of Rotation: For some objects, especially those that are far away or extremely small (like subatomic particles), detecting rotation might be challenging. However, for many macroscopic objects (like planets, stars, and galaxies), rotation can be directly measured.
No Absolute Non-Rotation: Because rotation is relative, there might be no universally agreed-upon "non-rotating" state. What appears non-rotating in one reference frame could appear rotating in another.
3. Cosmic Perspective:
General Relativity: In general relativity, rotation can be understood in more complex terms. For example, the concept of "frame-dragging" near massive rotating objects like black holes suggests that spacetime itself can be twisted by rotation.
Scale and Scope: On different scales, rotation manifests differently. For example, individual stars rotate, but so do entire galaxies. Classifying objects as rotating or not rotating depends heavily on the scale at which you’re observing.
4. Practical Utility:
Astrophysical and Engineering Applications: In many practical contexts, such as astrophysics and engineering, distinguishing between rotating and non-rotating objects is useful. For example, understanding the rotation of celestial bodies helps in predicting their behavior, like the formation of weather patterns on planets.
Conclusion:
While it is reasonable and useful to categorize objects in the universe as rotating or not rotating based on observations from a chosen reference frame, this classification is inherently relative and context-dependent. The division is a simplification that works well in many cases but may not capture the full complexity of rotational dynamics in the universe.
 
 
4o

 
You said:
With the rockets experiment in the empty universe is it then not demonstrated that rotation is not relative? The reference is the rocket and the measuring of its vertical trajectory.
 
ChatGPT said:
ChatGPT
The rockets experiment in an empty universe does indeed suggest that rotation is not entirely relative, at least in a specific context. Here's why:

1. The Role of the Rocket Trajectories:
In the scenario, the rockets serve as a way to measure whether the planet is spinning relative to itself, independent of any external reference points. The key observation is that if the planet were rotating, the rockets launched from different locations would exhibit different trajectories due to the Coriolis effect.
If both rockets show perfectly vertical trajectories with no horizontal deviation, this suggests that the planet is not spinning relative to itself, regardless of the absence of external reference points.
2. Rotation Relative to the Planet's Surface:
The experiment relies on observing the trajectories of the rockets relative to the planet’s surface. The fact that these trajectories are vertical implies that there is no rotational effect (such as the Coriolis effect) acting on the rockets.
This shows that, at least in this context, the planet's rotation (or lack thereof) is not relative to external objects but rather something that can be inferred directly by observing the behavior of objects in the planet's own reference frame.
3. Implications for the Relativity of Rotation:
Rotation Relative to an Internal Frame: The experiment demonstrates that the concept of rotation can be identified relative to an internal frame (the planet's surface) without needing an external reference. The absence of deviation in the rocket trajectories implies no rotation relative to the planet itself.
Absolute vs. Relative Rotation: While many aspects of motion are relative (e.g., linear velocity), rotation, in this case, can be identified as an intrinsic property of the system (the planet). This challenges the idea that rotation is entirely relative.
4. Mach's Principle and Inertial Frames:
Mach's principle suggests that local inertial frames are influenced by the distribution of mass in the universe. In an empty universe, without any external masses, one might argue that rotation should be meaningless. However, the rockets experiment shows that rotation (or its absence) can still be defined internally within the system, even in an empty universe.
This experiment hints at the idea that rotation has an "absolute" aspect to it, at least within the context of the system being considered.
Conclusion:
The rockets experiment demonstrates that rotation is not entirely relative. It shows that an observer on the planet can determine whether the planet is spinning based solely on the internal reference provided by the rocket trajectories. This implies that rotation can be an intrinsic property of a system, identifiable without the need for external reference points, thus challenging the notion that rotation is purely relative.