I Can angular motion exist outside of a gravity field?

AI Thread Summary
A centrifuge can indeed exist outside a gravitational field, as angular acceleration is possible in a void without external reference points. For instance, astronauts can experience centrifugal force while spinning around each other due to inertia, even without visible stars. The concept of rotating space stations, designed to simulate gravity through centrifugal force, illustrates this principle, although none have been built due to financial constraints. Discussions also touch on Mach's principle, which relates to inertia but diverges from modern physics. Overall, motion and acceleration can occur in a vacuum, driven by forces such as rocket engines or inertia.
jed1408
Messages
1
Reaction score
0
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?
 
Physics news on Phys.org
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.
 
  • Like
Likes Tom.G, vanhees71, AlexB23 and 1 other person
jed1408 said:
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.
 
  • Like
Likes malawi_glenn and vanhees71
jed1408 said:
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.
 
  • Like
Likes russ_watters, vanhees71 and PeroK
jed1408 said:
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?
:welcome:

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
 
  • Like
Likes gmax137 and mpresic3
Moderator's note: Thread title changed to be more descriptive.
 
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!
 
Clearly the electrons in our TV screens are in angular motion thanks to electromagnetic forces. No mention of gravity
 
mpresic3 said:
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?
 
  • #10
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?
 
  • #11
mpresic3 said:
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.
 
Back
Top