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(Big Think)   I knew the Universe wasn't rotating, but now, I want it to be   (bigthink.com) divider line
    More: Cool, General relativity, Black hole, Big Bang, expansion of the Universe, Kerr metric, black hole, rotating Universe, Universe  
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1230 clicks; posted to STEM » on 01 Jul 2022 at 1:40 PM (6 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



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2022-07-01 11:17:48 AM  
Rotating in relation to what? Nothingness?
 
2022-07-01 11:20:31 AM  
Why do "journalists" always have to use question headlines?
 
2022-07-01 12:14:56 PM  
We all know how this ends up:

Fark user imageView Full Size
 
2022-07-01 12:25:18 PM  

Lambskincoat: Rotating in relation to what? Nothingness?


The center?
 
2022-07-01 1:44:19 PM  
Fark user imageView Full Size
 
2022-07-01 1:47:19 PM  

whidbey: Why do "journalists" always have to use question headlines?


Click here to find out! The answer may shock you!
 
2022-07-01 1:51:51 PM  

Lambskincoat: Rotating in relation to what? Nothingness?


Presumably expanding in a rotational manner.  Not sure how we'd measure it, as presumably the velocity would be sideways so there wouldn't be any redshift.

If I had the math I'd check this.  A whole lot of rotating mass might go a long way for dark energy, and if done in tricky 4D expansion space might have been ignored or difficult to detect.
 
2022-07-01 2:01:37 PM  
Billy Preston - Will It Go Round In Circles
Youtube I_e-RQZVwxg
 
2022-07-01 2:15:35 PM  
Josie and the Pussycats (2001) - Spin Around Scene (10/10) | Movieclips
Youtube a2o2cQ7oNPM
 
2022-07-01 2:26:05 PM  

Lambskincoat: Rotating in relation to what? Nothingness?


Maybe, but for all we know it could be a giant bowl of pudding.
 
2022-07-01 3:08:41 PM  

whidbey: Why do "journalists" always have to use question headlines?


Ethan isn't a journalist
 
2022-07-01 3:15:20 PM  
Owls: Nature's gyroscopes

Rotate Your Owl : animated music video : MrWeebl
Youtube 9hBpF_Zj4OA
 
2022-07-01 3:26:39 PM  

Lambskincoat: Rotating in relation to what? Nothingness?


A major concept in the theory of relativity is that while you can't measure velocity without a reference point to measure it against, rotation *can* be measured in the absence of a reference point.

IE, if I put you in an elevator car under constant acceleration, you can't tell if you're standing still or moving with reference to anything outside that car (IE, are you sitting on the surface of the earth or accelerating through space at the same acceleration as the acceleration due to gravity at the surface of the earth). But if I spin that car, you can measure that without reference to anything outside the vehicle.
 
2022-07-01 3:38:16 PM  

TrevorSmith: Lambskincoat: Rotating in relation to what? Nothingness?

A major concept in the theory of relativity is that while you can't measure velocity without a reference point to measure it against, rotation *can* be measured in the absence of a reference point.

IE, if I put you in an elevator car under constant acceleration, you can't tell if you're standing still or moving with reference to anything outside that car (IE, are you sitting on the surface of the earth or accelerating through space at the same acceleration as the acceleration due to gravity at the surface of the earth). But if I spin that car, you can measure that without reference to anything outside the vehicle.


Now is there a way to measure 4-D coriolis effects?
 
2022-07-01 4:34:44 PM  
Just what is the infinite universe supposed to be rotating in relation to?
 
2022-07-01 4:47:04 PM  

TrevorSmith: But if I spin that car, you can measure that without reference to anything outside the vehicle.


What if you have a planet of, say, Earth mass, rotating, say, once a day? Would the creatures populating it be able to perceive the rotation without any reference to anything outside the planet?
 
2022-07-01 5:32:30 PM  

Lambskincoat: Rotating in relation to what? Nothingness?


Rotating in relation to all the other stuff in the universe.

That is, if we look in one direction for long enough, we could detect transverse motion. If we looked at the other 5 axes for the same amount of time, we should see 4 within the same plane showing the same amount of transverse motion, while objects above and below that plane would show less or no motion.

Observation to date shows everything receding from the Earth, no matter which direction you look, so it's as if we're at the center of the Big Bang. So, how would you choose which direction to observe?

My gut instinct is that Special Relativity precludes being able to detect rotation of the entire universe. An object at the edge of the universe should still show expansion of all its nearest objects (as if it was the center of the Big Bang), and other objects are too far away to obtain a measurement.

Interesting idea, but not likely to be measurable.
 
2022-07-01 5:41:21 PM  

TrevorSmith: Lambskincoat: Rotating in relation to what? Nothingness?

A major concept in the theory of relativity is that while you can't measure velocity without a reference point to measure it against, rotation *can* be measured in the absence of a reference point.

IE, if I put you in an elevator car under constant acceleration, you can't tell if you're standing still or moving with reference to anything outside that car (IE, are you sitting on the surface of the earth or accelerating through space at the same acceleration as the acceleration due to gravity at the surface of the earth). But if I spin that car, you can measure that without reference to anything outside the vehicle.


To add, a pendulum suspended from the ceiling of elevator car would swing in a pattern, not just back and forth.

You can use the pendulum method to determine your latitude on Earth. At the North Pole, you would see it precessing (if I have my concepts right), making a full rotation every day. At the Equator, there's no precession; the pendulum stays in the same plane.
 
2022-07-01 5:51:35 PM  

Unsung_Hero: Just what is the infinite universe supposed to be rotating in relation to?


The other ones surrounding it.
 
2022-07-01 5:53:45 PM  

PartTimeBuddha: TrevorSmith: But if I spin that car, you can measure that without reference to anything outside the vehicle.

What if you have a planet of, say, Earth mass, rotating, say, once a day? Would the creatures populating it be able to perceive the rotation without any reference to anything outside the planet?


Yes.
upload.wikimedia.orgView Full Size
 
2022-07-01 7:14:37 PM  
Fark user imageView Full Size
 
2022-07-01 7:18:01 PM  
When we look out at the Universe, we can see objects in all directions, spanning tens of billions of light-years

this is where I stopt reading.png
i.pinimg.comView Full Size
 
2022-07-01 7:41:01 PM  

Be polite walk on the right: When we look out at the Universe, we can see objects in all directions, spanning tens of billions of light-years

this is where I stopt reading.png
[i.pinimg.com image 498x368]


Possibly true, if you're measuring co-moving distance.  That can go up to 45 billion light years.
 
2022-07-01 8:32:55 PM  
mir-s3-cdn-cf.behance.netView Full Size
 
2022-07-01 10:38:19 PM  

TrevorSmith: Lambskincoat: Rotating in relation to what? Nothingness?

A major concept in the theory of relativity is that while you can't measure velocity without a reference point to measure it against, rotation *can* be measured in the absence of a reference point.

IE, if I put you in an elevator car under constant acceleration, you can't tell if you're standing still or moving with reference to anything outside that car (IE, are you sitting on the surface of the earth or accelerating through space at the same acceleration as the acceleration due to gravity at the surface of the earth). But if I spin that car, you can measure that without reference to anything outside the vehicle.


You can measure changes in rotation, just as you can changes in acceleration.  How does one measure rotation when the entire system including the detector is all rotating at the same rate over time? Would universal rotation change during the Cosmic Inflationary period when Space was expanding super-luminally?
 
2022-07-01 10:44:07 PM  

yet_another_wumpus: Lambskincoat: Rotating in relation to what? Nothingness?

Presumably expanding in a rotational manner.  Not sure how we'd measure it, as presumably the velocity would be sideways so there wouldn't be any redshift.

If I had the math I'd check this.  A whole lot of rotating mass might go a long way for dark energy, and if done in tricky 4D expansion space might have been ignored or difficult to detect.


I say it's wobbling. Or maybe juttering up and down. Prove me wrong.
 
2022-07-02 5:14:06 AM  

AdrienVeidt: TrevorSmith: Lambskincoat: Rotating in relation to what? Nothingness?

A major concept in the theory of relativity is that while you can't measure velocity without a reference point to measure it against, rotation *can* be measured in the absence of a reference point.

IE, if I put you in an elevator car under constant acceleration, you can't tell if you're standing still or moving with reference to anything outside that car (IE, are you sitting on the surface of the earth or accelerating through space at the same acceleration as the acceleration due to gravity at the surface of the earth). But if I spin that car, you can measure that without reference to anything outside the vehicle.

You can measure changes in rotation, just as you can changes in acceleration.  How does one measure rotation when the entire system including the detector is all rotating at the same rate over time? Would universal rotation change during the Cosmic Inflationary period when Space was expanding super-luminally?


Wouldnt it be safer to just assume the universe has its own rotation since every object inside it is rotating, no matter the size of the object??
 
2022-07-02 8:24:27 AM  

AdrienVeidt: You can measure changes in rotation,


You can measure *rotation* even if it's at a constant rate.
 
2022-07-02 10:10:57 AM  
 
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