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You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move?
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Theres billions of tiny strings called gravity that go from each star to your arms. When you spin, those strings are pulled taut.
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Rotational velocidensity.
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It's better when you put a big spinny plate on the ceiling and then look at that
When it's spinning your arms are at your side
Match the spin, and now it's stopped
Your arms are pulled out
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>>10377896
Frame dragging or Mach's principle.
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>>10378104
This
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>>10377896
Centrifugal(centripetal) force. Acceleration always produces a perceived force. Any other stupid questions?
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>>10378564
Relative to what inertial frame, an absolute time and space determined by the mass of the universe? Why is there centrifugal force when the stars are whirling, but no centrifugal force when the stars are still, why is one frame prefrenced.
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>>10377912
So we can say the mass of the universe gives us an absolute time and space in regards to rotation, and rotation (in the universe) is always absolute rather than relative?
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>>10379155
The stars are not part of it. The centrifugal force would exist whether the stars existed, or if you were just spinning in an empty void entirely separate from this universe. Forget about the fucking stars. There is no frame of reference needed to be defined as stationary when there is ACCELERATION involved. Acceleration need not be relative to outside refrence frames, just relative to your own reference frame at a different point in time. There is no preference in frame of reference going on here. You are thinking that spinning in a CIRCLE only involves velocity, that is false. Any change in velocity is acceleration, including changes in direction like TURNING.
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>>10378564
>>10379155
>Brainlets who don't understand the fundamental issue
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>>10379237
>acceleration
Spinning isn't acceleration, it's speed. Set anything spinning in space, and it will continue to spin.
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>>10379970
no, it's acceleration
spin a bunch of dust and they'll all go flying outwards
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>>10379970
Acceleration is a change in velocity. Velocity is a speed in a direction. Change the speed, or change the direction, and you have acceleration. What are the tips of your fingers doing when you spin with your arms out? They arent moving is a straight line, I can tell you that.

>>10379966
>Brainlet who doesn’t understand high school intro to physics concepts.
Explain it to me, oh wise one. What am I missing?
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>>10380007
>Acceleration is a change in velocity. Velocity is a speed in a direction. Change the speed, or change the direction, and you have acceleration.

Yes, you are correct.

>Explain it to me, oh wise one. What am I missing?

The problem is why an 'absolute' rotational frame of reference seems to exist, such that an object can be considered rotating, and another devoid of rotational velocity, instead of this being a relative thing. It was a fundamental issue that Einstein saw as a serious problem.
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>>10380060
the issue here is that an object can be considered to be rotating when parts of itself are moving relative to other parts
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>>10380060
Finally, someone besides me (>>10378122) who sees the deeper issue.
It would funny if this problem that Einstein recognized and everybody ignored for a century turns out to be the missing piece of GR.
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>>10379155
>when the stars are whirling
Kek. Too easily bait. You'd need to be retarded otherwise.
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>>10380060
>The problem is why an 'absolute' rotational frame of reference seems to exist, such that an object can be considered rotating, and another devoid of rotational velocity, instead of this being a relative thing. It was a fundamental issue that Einstein saw as a serious problem.
How is that not a "relative thing"?
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>>10377912
Based and Gaede pilled
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>>10380060
>The problem is why an 'absolute' rotational frame of reference seems to exist, such that an object can be considered rotating, and another devoid of rotational velocity, instead of this being a relative thing. It was a fundamental issue that Einstein saw as a serious problem.
Are you suggesting that centripetal/centrifugal force is related to space time in a similar way to gravity? Space is being altered somehow and we perceive it as a force? I guess the best way to express this would be to approximate a rotation as a sequence of movements?
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>>10380007
>What am I missing?
http://www-groups.dcs.st-and.ac.uk/history/HistTopics/Newton_bucket.html
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>>10380118
How do the stars know you're rotating? Is it because the mass of the universe forms a non-rotating rest frame against which absolute non-relative rotation can be measured by all observers?
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>>10377912
So the stars reach out and lift women's skirts when they spin?
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i mean, for the people who are not seeing the point at all, imagine two people floating in the middle of interstellar space. Posed as if standing upright and one on top of the other so were they to spin it would be about the same axis. Now, if they have translation velocity apart from each other, neither could say, I am moving not them, or they and not I or any which inbetween. It's all relative only.
But if they have relative angular velocity wrt each other, it can be that the top person looks down and sees the bottom spinning, arms flung out, or the bottom person looks up and sees the top person spinning, (from their point of view) even though the top person's arms are not flung out and mine are, so it must be the bottom person spinning and not the top. Hence both can know the that bottom is rotating *with respect to the universe* and the top is not
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>>10380238
AAAAAAAAAA NOOOOO MY PRECIOUS RELATIVITY AAAAAAAAA ABSOLUTE ROTATION AAAAAAAAAAAA
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>>10378564
>>10379237
>>10380090
>>10380118
The problem is rotation defies relativity and appears to be absolute because of centrifugal force, see:
https://www.youtube.com/watch?v=cPEwkMHRjZU&t=180s
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>>10380238
i think the issue here is the fact that rotation is an arbitrary, intuitive thing. zoom in far enough and you just see a bunch of particles constantly being accelerated to change the direction of their travel. the system just happens to be set up in a way that it's very stable and loses very little energy while doing this, leading to idealized mathematical depictions of it like angular momentum.
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>>10380567
hmm this actually... could make sense i mean only configurations of points can 'rotate' if points themselves don't have any kind of 'orientation'. i wonder if fundamental particles wave functions or whatever have any orientation
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>>10380060
>>10380112
I get that you think you are showing me something I don’t understand here, but you arent getting it. Let me break it down... again.
Its not that there is an “absolute rotational frame”. Its that ACCELERATION ITSELF is absolute. No two frames of reference will ever disagree on the rate at which something is changing its velocity, as long as those frames are not themselves ACCELERATING. Two frames can disagree on an objects speed, or velocity all day long, based on their own speed or velocity. They will never disagree on the objects ACCELERATION, reguardless of their own velocity as long as that velocity is not changing. Do you get it now?
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>>10380695
>Do you get it now?
I don't disagree with you about anything. The point is that acceleration being absolute, and centrifugal force being a result of this, implies an essentially stable orientation of space, such that an object rotating with respect to that will necessarily have acceleration of its parts.

[spoiler]If you were the second guy I quoted I didn't mean to quote you.[/spoiler]
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>>10380211
I understand what you mean now. Less banal that what it seemed, I would immediately argue that
>absolute non-relative rotation
is bullshit. I'll lurk more.
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>>10380755
See the vid from the timestamp here>>10380524. The problem is:
1. If the universe rotated around you while you stood still then your arms wouldn't fling out; you wouldn't experience centrifugal force.
2. If you rotate inside the universe your arms do fling out; you do experience centrifugal force.
3. Your motion relative to the stars should be the equivalent of the motion of the stars rotating around you, it should just be a question of the observers reference frame: to the observer on the star you are rotating, to you the stars are rotating around your field of vision.
4. But the absence or presence of the centrifugal force on your arms would be observed by all observers.
5. Therefore the motion of rotation is not relative to the observer but is absolute, we know that it is you rotating, not the stars/universe: you know this, the stars know this, a hypothetical observer outside the universe would know this, because you have centrifugal force acting upon you.
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>>10380720
>implies a stable orientation of space
No, it doesnt. Acceleration is essentially a change in frame of reference. Absolute VELOCITY would imply a stable orientation of space. You can run tests in a closed system with no reference point to see if you are in an inertial frame of reference. If the test fails, you are ACCELERATING. I really cant make it much clearer than that. Just know, that I know what you are trying to say, you are just wrong.
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>>10380847
>1. If the universe rotated around you while you stood still then your arms wouldn't fling out; you wouldn't experience centrifugal force.
How do you know? This would require you to calculate the gravitational effect of the entire universe throughout all time on the observer.
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>>10380859
He is right, to a point. If all matter in the universe rotated around you, your arms wouldnt get pulled out. No calculations necessary. If spacetime rotated around you, its hard to say what the difference would be compared to you spinning.
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>>10380859
Modify the statement to say only the matter rotates, e.g. only the stars. Imagine looking up and seeing the stars as fast moving streaks (i.e. the same as what you see in your distorted field of vision when you spin around at night, except imagine you see that but you're not spinning.)
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You are standing in a field looking at the stars. Now tell the stars "numbers have an end" so that you may be blessed with Divine understanding.
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https://en.wikipedia.org/wiki/Woodward_effect

link extremely related
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>>10380865
https://en.wikipedia.org/wiki/Frame-dragging
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>>10380897
Link not related at all, except by the coincidental shared name "Mach." Nice LARP.
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>>10380906
Just how dumb are you really?

https://hacked.com/move-emdrive-comes-woodwards-mach-effect-drive/
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>>10380904
Thanks for letting me know you don’t understand GR or frame dragging.
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>>10380897
Thank you anon. I cannot believe i had not heard of this before.
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>>10380963

You are very welcome.
It's weird how little media coverage there is for this.

I mean, I know of no other theory that could change so much if true.
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bump
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>>10380893
Thank you, brother. I now see the light.
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one guy already said it and nobody picked up on it. rotation doesn't exist it's just a convenient conceptual abstraction. none of the particles of an object are 'rotating' they are moving linearly and being accelerated laterally
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>>10382570
But why? If the stars are rotating rather than the you, then you don't experience the centrifugal/perpendicular force. If you are rotating and the stars are standing still, you do experience the centrifugal/perpendicular force. One frame of reference is preferenced with absolute rather than relative motion, see the vid here>>10380524
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>>10377896
Coincidence. If stars generated gravitational field centered inside you, then your arms would dangle freely when you spin.
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>>10380221
Not the anon you replied to, but I kek'd at the filename
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>>10383276
don't fucking tell me to watch a kids video about the premise of the question cunt, i'm hypothesising a path to the anwser. Think about how something that's 'rotating' might decompose into pieces undergoing linear motion and then look at what's going on in the reference frame of the pieces monetarily where there's no concept of 'rotation'.
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>>10377896
Arms are connected to my body so I communicate them momentum by spinning. The stars aren't connected to my body (and are fucking massive anyway) so they don't move and I only see them moving because I am moving myself.
Literally no problem here, what the fuck is this Mach's principle all about? Explain to brainlet pls
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What the fuck is this all about. If you spin, if you activated your body muscles to perform a rotating movement, then it is absoluetely obvious that you were the one rotating. If general relativity doesn't say that, general relativity is retarded.
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>>10383440
Now we're getting somewhere. It is a good stab at the problem but I think you're missing what the fundamental issue is:
https://www.youtube.com/watch?v=s6NY8Ikhwtg&t=134s
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>>10383470
The problem is that rotation isn't relative, unlike every other force or motion in SR and GR: one frame is certain to be rotating because it experiences centrifugal force. GR may provide a mechanism for how cosmic mass out there can affect local rotational motion, and if the mass distribution of the universe is homogenous then perhaps that effect would somewhat mimic absolute space at least in regards to rotation. Not sure if it is satisfactory desu.
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>>10383561
But what's the point in actling you dont know which object is rotating (or generally moving, for that matter) if you know 100% which object is actually the one that moves? Let's say you have a remotely controlled car, and you push the button that accelerates the car. Why are you acting now you dont know if the car is moving or the universe around it? You pushed the button, so you know for sure its the car moving.
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>>10379155
>Why is there centrifugal force when the stars are whirling
The stars aren't whirling, YOU are whirling.
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>>10383458
The problem is rotation is not relative. Your description is Newtonian and premised on absolute time and space. If the reverse happened and the stars spun around you then your arms wouldn't pull out, the rotational motion appears to be absolute: as the stars spin around your head any observer would know if either it was the stars rotating (arms stay by side) or if it was you rotating (arms pulled out), which doesn't jive with the relativity principle that says it should be dependent on the observers reference frame.
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>>10383589
>so you know for sure its the car moving.
No you don't. You could be in a reference frame that is moving backwards relative to the car standing still and it would appear the same.
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>>10383595
And there's the problem. We know absolutely who is whirling and who is not, it's not relative.
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>>10383599
For example it's not meaningful to ask "is the Voyager 1 probe moving away from the solar system, or is the solar system moving away from the Voyager 1 probe?" It depends on your reference frame and either description is valid. But not so with rotation which appears to be absolute: one thing is rotating, another is not.
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>>10383599
But you definetely are not, because you know for sure that you accelerated the car, not the universe.
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>>10383645
Not to an observer on the car. The observer on the car can perceive it is standing still and has accelerated you away. The motion is dependent on the observers reference frame and looks the same either way define it. Not so rotation, only the absolutely rotating observer experiences centrifugal force.
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>>10380060
Einstein was an idiot.
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Popsci article on the problem of absolute rotation, Mach's principle, Newton's bucket and GR:
https://www.americanscientist.org/article/the-forgotten-mystery-of-inertia
http://archive.is/vgbTJ
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>>10377896
That's pretty interesting considering that essentially everything in the universe rotates. Maybe understanding rotation is the key to understanding the universe.
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you're just looking at the static firmament
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>>10383868
>the rotation of the universe pushes the stars onto the spinning celestial sphere affixing them by centrifugal force
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>>10380893
Amen. Numbers have an end.
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>>10380893
At last. I truly see.
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>>10379970
It's a change in velocity, nigger. I learned this shit in my freshman year of high school, /sci/ truly is retarded.
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>>10380893
Thank you. I wish good fortune upon you for generations to come.
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>>10380893
I believe! I believe! The sky has parted, and now I see. Numbers do have an end.
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>>10383852
Dude what if quantum spin and the Paulie principle are determined by Machian interactions with the mass of the universe?



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