Can angular motion exist outside of a gravity field?

[jed1408]

I can't find the answer anywhere here's my question. can a centrifuge exist outside a field of gravity. More specifically, in a theoretical void of nothing without stars in view or any point of reference for comparison how could motion like spinning or acceleration exist?

 

[DaveC426913]

Hello and welcome.

Yes. Angular acceleration can occur in the absence of gravity or other masses.

If astronauts Alice and Bob held hands and turned on their maneuvering jets, they would pirouette around each other like a planet and moon.

Whether or not they could see an external reference point such as a star, they would experience a centrifugal pull trying to separate them. This pull is simply inertia - their bodies trying to proceed in straight lines but constrained to go in a curve. All things with mass have inertia.

 

[russ_watters]

More specifically, in a theoretical void of nothing without stars in view or any point of reference for comparison how could motion like spinning or acceleration exist?

How can they exist or how do we know? Obviously you use rocket engines to make acceleration happen in space. And you know you're accelerating because you can feel it or measure it with an accelerometer.

Moving this thread to Classical Physics.

 

[AlexB23]

I can't find the answer anywhere here's my question. can a centrifuge exist outside a field of gravity. More specifically, in a theoretical void of nothing without stars in view or any point of reference for comparison how could motion like spinning or acceleration exist?

A centrifuge can exist without a field of gravity. Back in the 20th century, scientists and futurists developed concepts for rotating space stations, which are basically giant centrifuges. At a certain speed, which can be calculated by station radius and revolutions per unit time, the force inside the space station would equal 1 G. Sadly, due to cost restraints, no rotating space station has been built.

 

[PeroK]

I can't find the answer anywhere here's my question. can a centrifuge exist outside a field of gravity. More specifically, in a theoretical void of nothing without stars in view or any point of reference for comparison how could motion like spinning or acceleration exist?

You've got some simple (and IMO correct) answers. If, however, you would like a trip down a philosophical rabbit hole, you could read up on Mach's principle:

https://en.wikipedia.org/wiki/Mach's_principle

 

[PeterDonis]

Moderator's note: Thread title changed to be more descriptive.

 

[vanhees71]

But Mach's principle is neither a clear concept nor has it anything to do with the modern understanding of physics of spacetime, i.e., general relativity, although Einstein said that he was inspired by Mach's ideas on inertia. As you say, indeed it's a philosophical rabbit hole!

 

[mpresic3]

Clearly the electrons in our TV screens are in angular motion thanks to electromagnetic forces. No mention of gravity

 

[renormalize]

Clearly the electrons in our TV screens are in angular motion thanks to electromagnetic forces. No mention of gravity

Can you "clearly" describe the "angular motion" that you think electromagnetic forces impart to electrons in TV screens? And are you referring to older CRT-based TVs or current LCD/LED displays?

 

[mpresic3]

I am saying an electron beam starts out (say) along the x axis, and later is is deflected say by angle theta. Isn't this angular motion?

 

[PeterDonis]

Isn't this angular motion?

In a sense it is, but it's not "spinning" like a "centrifuge", which are the terms the OP of this thread used.