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metastable
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The subject of the thread summarizes my question: Could the accelerating expansion be explained by a "spinning" universe?
metastable said:Could the accelerating expansion be explained by a "spinning" universe?
If I have a bowl full of jello and suspended coffee beans, and I spin the bowl fast enough, I'd expect the beans to accelerate away from the rotation axis...PeterDonis said:Why would you expect a spinning universe to lead to accelerated expansion?
metastable said:If I have a bowl full of jello and suspended coffee beans, and I spin the bowl fast enough, I'd expect the beans to accelerate away from the rotation axis...
metastable said:I believe it’s thought there is no “preferred rest frame” in the universe... ie if i’m weightless in a closed elevator I can’t tell whether I’m accelerating in a gravitational field or just coasting through empty space.
On the other hand if the elevator is “spinning” I believe I can infer or measure this from inside the elevator without seeing the rest of the universe.
If the universe has no preferred frame of reference, why am I able to observe that the elevator spins while I’m weightless in the closed elevator? What is the elevator spinning relative to?
PeroK said:Spinning would be a particular case of proper acceleration and a particular case of a non geodesic worldline.
metastable said:Would the particles that make up the elevator which are located directly along the free-falling-through-empty space-elevator’s axis of spin also be considered to be in a state of proper acceleration? If not, what are these spinning relative to?
So if the elevator spins at 1000rad/sec, and discharges a single electron into the vacuum, will the electron retain any of the elevator’s classical angular speed or will the electron’s spin be the entirely quantum-mechanical concept of spin? If the emitted electron does retain some or all of the elevator’s 1000rad/sec classical spin, what would this additional spin (above and beyond the intrinsic quantum mechanical spin) be relative to?PeroK said:If we are talking microscopic particles here then a rigid body is not really a contiguous rigid body. The particles will have thermal motions and quantum mechanical properties.
In addition, the axis of rotation would in general be empty space!
Ibix said:That would imply a special axis about which it is spinning, which would seem to lead to anisotropy even if we lie on the axis. The sky is remarkably isotropic on large scales, so I don't think this is plausible.
metastable said:If the universe as a whole were not only spinning, but precessing as well, and both spin rate and precession rate were increasing, can this lead to isotropic accelerating expansion?
Bandersnatch said:By anisotropy @Ibix meant that a spinning thing, be it skater or a universe, looks different along the axis of rotation than perpendicular to it. Whether it also precesses makes no difference in this regard.
PeterDonis said:No. There is no way for any kind of spinning to look the same in all directions.
It will change the axis. But it will never make the universe look isotropic. It just gives you a time-varying anisotropy.metastable said:I guess I'm confused because I thought that adding a second axis of rotation would alter the vectors of the centrifugal forces experienced by particles in a reference frame with both accelerating rotation and accelerating precession...
A "spinning" universe refers to the idea that the universe is rotating or spinning on its axis. This concept is based on the theory of general relativity, which suggests that the universe is not static but constantly expanding and rotating.
According to the theory of general relativity, the rotation of the universe creates a force known as the "frame-dragging effect." This force could potentially contribute to the acceleration of the expansion of the universe by pulling matter and energy outward.
While there have been some observations that suggest the universe may have a slight rotation, there is currently no conclusive evidence to support the idea of a "spinning" universe. This concept is still a topic of debate and further research is needed to fully understand the dynamics of the universe.
Yes, there are other theories and models that attempt to explain the accelerating expansion of the universe, such as dark energy and modified theories of gravity. These explanations do not involve a "spinning" universe and are still being studied and tested.
One way to test the theory of a "spinning" universe is through observations of the cosmic microwave background radiation, which is the remnant heat from the Big Bang. If the universe is rotating, it would leave a distinct pattern in this radiation that can be detected by telescopes and satellites. Other methods include studying the distribution of galaxies and measuring the effects of the frame-dragging force on nearby objects.