Can a Ring Laser Interferometer Measure Earth's Spin and Determine Latitude?

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Discussion Overview

The discussion revolves around the feasibility of measuring Earth's spin vector and determining latitude using various devices, including gyroscopes, sextants, pendulums, and ring laser interferometers. Participants explore the technical challenges and limitations of these methods without external references or celestial objects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about devices that can measure Earth's spin vector and forces without external references.
  • Several participants suggest using gyroscopes, but express concerns about their alignment and setup requirements.
  • Another participant proposes using a sextant to measure the elevation of Polaris, although this involves celestial referencing.
  • A pendulum is mentioned as a potential tool, but its effectiveness is debated.
  • Some participants note that distinguishing between gravitational and rotational forces is complex, especially without external references.
  • One participant shares their experience with a precision gyroscope that did not yield expected results, attributing this to internal friction.
  • There is a discussion about the expected behavior of a gyroscope in relation to Earth's rotation, with some participants questioning the conditions under which it should show changes.
  • A later reply suggests that a ring laser interferometer may provide more reliable measurements than a gyroscope.

Areas of Agreement / Disagreement

Participants express differing opinions on the effectiveness of various devices for measuring Earth's spin and determining latitude. There is no consensus on a definitive method, and several competing views remain regarding the capabilities and limitations of the proposed devices.

Contextual Notes

Participants acknowledge the overlap between gravitational and rotational forces, particularly at different latitudes, but do not resolve the implications of these interactions for measurement techniques. The discussion includes uncertainties about the conditions necessary for accurate measurements.

aladinlamp
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Hi

is there any device or experiment, which could measure Earth spin vector and magnitude, centrifugal/centripetal forces, so i could derive from it, where is west and east , what's the vector of Earth rotation and what's my lattitude.

Im assuming these forces and effects has to be measurable with todays technology.

the device will be stationary, non moving( car, aeroplane), without external referencing, celestial objects,etc...

spin.jpg
 
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Gyroscope.
 
Tom.G said:
Gyroscope.
Trouble with a gyroscope is it needs to be set up and aligned, so i don't think it can measure the eart's rotation axis.

My choice would be a sextant, measuring the elevation of Polaris (and with more complex calcs, you can get closer than a half degree).

For the period...a clock is all you need, and a view of the horizon.

For forces, that is a lot tougher since gravity and the rotational forces overlap. I'm not sure there is a way to distinguish them in measurements(unless you own a satellite); only in calculations.
 
Pendulum?
 
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Tom.G said:
Gyroscope.
i tried with precision gyroscope, did not work,did not move, i guess too much internal friction in joints
 
russ_watters said:
Trouble with a gyroscope is it needs to be set up and aligned, so i don't think it can measure the eart's rotation axis.

My choice would be a sextant, measuring the elevation of Polaris (and with more complex calcs, you can get closer than a half degree).

For the period...a clock is all you need, and a view of the horizon.

For forces, that is a lot tougher since gravity and the rotational forces overlap. I'm not sure there is a way to distinguish them in measurements(unless you own a satellite); only in calculations.

I meant device without referencing celestial objects, just blindly measuring forces and vectors ( inside the box)

gravity and the rotational forces overlap, that's true but on poles rotational forces should be zero and at equator should be max, so has to be measurable difference there, from which lattitude could be derived
 
aladinlamp said:
i tried with precision gyroscope, did not work,did not move, i guess too much internal friction in joints
A gyroscope measures what happens when you move.
I meantdevice without referencing celestial objects, just blindly measuring forces and vectors ( inside the box)
Other than a pendulum to measure the rotation rate, I don't think what you are after can be done.
gravity and the rotational forces overlap, that's true but on poles rotational forces should be zero and at equator should be max, so has to be measurable difference there, from which lattitude could be derived
That would only be true if the gravitational component of the force were constant, which it isn't.
 
russ_watters said:
A gyroscope measures what happens when you move.
.

yes groscope disk should change angle relative to base, since gyroscope base is moving with earth, but no angle change for me

gyr.gif
 
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aladinlamp said:
yes groscope disk should change angle relative to base, since gyroscope base is moving with earth, but no angle change for me

View attachment 104490
How far did you move?
 
  • #10
russ_watters said:
How far did you move?

once spun to max revolutions, it took 27 minutes for the disk to stop, i know it needs high rpm all the time, but should move at least few degrees

7.5 degress in 30 minutes, if all was by the book
 
  • #11
aladinlamp said:
once spun to max revolutions, it took 27 minutes for the disk to stop, i know it needs high rpm all the time, but should move at least few degrees

7.5 degress in 30 minutes, if all was by the book
What direction was the axis pointed?
 
  • #12
russ_watters said:
What direction was the axis pointed?
of course i tried all possible angles and orientations, nothing happened
 
  • #13
You can use a Foucault pendulum to measure your latitude.

A ring laser interferometer will be more reliable than a gyroscope, particularly since it sounds like your gimbal has sticky bearings.
 
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