Spining Problem

[CraigD]

I hope to return after a bit of heavy reading and actually frame my real puzzle intelligently - unless it is one of those useless wonderings, like "What was before the big bang?"

Best wishes in your studies! I look forward to your future posts.

Answers like this quote in a similar forum suggest I had better lay off till I know more.

The Milky Way is turning, and from where we are, 30,000 light years from the Galactic centre, is taking our Solar system with it at half a million miles per hour in the first direction to establish stage one of the formation of 'Gyrotic' Gravity. …

I’d not worry overmuch about any failure to understand “‘Gyrotic’ Gravity” – it appears to be something the quoted poster just made up on the spot in a confused effort to equate inertia, electromagnetic force (the largest force involved in keeping water in buckets, and keeping ones grip on buckets when swinging the overhead), and gravity. I think the next post in that forum put it well:

huhhh?

 

Glactus, you described centripetal acceleration w/ the swinging bucket example - not 'inert gravity' whatever that is. And 'gyrotic' isnt even a word in the dictionary.

[Boerseun]

This is actually a pretty nifty discussion! (Joining in a bit late, though...)

 

THERE ARE NO UNIVERSAL "FRAMES OF REFERENCE" - Basically, Einstein's spiel.

 

So, how come if I spin a gyroscope, it stays in the plane in which I started spinning it? The planet will revolve under the gyro, making the gyro describe a complete 'circle' once a day, with respect to the planet's surface.

 

Now, if I tie a box to the gyro's axis, I've got one of the boxes' planes in xyz space inertially stable. So, let's fix a gyro to the y and z planes as well. So, now the box is inertially stabilised in all three dimensions, and the planet can rock and roll and robustly rotate and really revel in its roundedness as much as it wants, but the box is inertially tied... to what?

 

Let's say at the same time, a similar box was constructed in the back yard of a fat Finklefrooble, using illegal Smyrthaffingag labour, on Zebbledygook 5, a planet in the Vavoom Galaxy. That box will also be inertially tied... to what?

 

The box will protest against the rotation of the planet, turning on its NS axis once a day. But if you're patient, you'll also see the box protesting against the planet's orbit around the sun. And if you're really patient, you'll see the box kicking against the solar system's orbit around the galactic core, or in the case of Finklefrooble, around the center of the Vavoom Galaxy.

 

So... are there really no priviledged frames of reference, or am I simply muddling the issues? I suspect the latter, but it still is a fun exercise...

 

This is basically the gist of the question of rotating in interstellar or even intergalactic space. You're rotating, but in respect to what? Sure, you can see galaxies and stars rotating around you, and the speed at which they are doing it seems to be in violation of the sanctity of c. So, you must be the one doing the spinning. But in relation to what frame of reference, seeing as there are no priviledged ones? How does inertial stability plug into Einstein's universe?

[ronthepon]

Hmmm... I doubt if rotation is analogous to linear motion, when it comes to relativeness.

 

When something is rotating with a specific angular velocity, then the frame of reference upon it is non inertial, and hence feels a centrifugal force.

 

This centrifugal force is having a well and clearly defined zero value, unlike velocity, which is always measured relative to something. I mean the coin will move away when there is an angular speed of above zero, and will move away at a speed proportional to the angular speed.