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The Sun's surface mysteriously rotates more slowly than its interior. Now researchers have observed the phenomenon with high resolution and proposed an explanation for the behavior. Using a new technique that tracks waves moving through the outer layers of the Sun, the team confirmed the speed difference and attributed the slowdown to the Sun's outer, 70-km "skin." Their model proposes that photons radiated from this layer extract angular momentum, slowing down the rotation. According to the researchers, such a slowdown should occur in all stars and could have a greater effect on larger stars.
The rotation rate of the Sun's plasma varies with latitude—faster at the equator than at the poles—and with distance from the core. Solar researchers noticed the core-surface speed difference decades ago but do not yet have a widely-accepted explanation.
This rotational anomaly has been implicated in solar flares... so nice to know the cause.
(Score: 3, Interesting) by JoeMerchant on Tuesday February 07 2017, @01:17PM
Something I found mind-bending when I grasped it: according to general relativity, when a photon is emitted at the speed of light - from its frame of reference, it immediately arrives at its destination.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Tuesday February 07 2017, @01:32PM
Topic is radial. Comment is tangential.
(Score: 1, Touché) by Anonymous Coward on Tuesday February 07 2017, @03:10PM
To carry away angular momentum, the photons need to have a tangential component of velocity.
(Score: 2, Informative) by Anonymous Coward on Tuesday February 07 2017, @03:06PM
Which means you didn't completely grasp it: There is no frame of reference for the photon. Indeed, in the limit(!) v→c, the spatial direction of movement and the direction of time coincide. Or said in another way, the photon "frame" lacks a dimension. Also note that due to Lorentz contraction, in the limit v→c the distance to the destination goes to zero; this is consistent as you obviously need zero time to pass a zero distance with the speed of light (which of course doesn't change in the limit v→c).
(Score: 0) by Anonymous Coward on Tuesday February 07 2017, @03:49PM
That makes an incredible amount of sense. I'd never quite understood contraction in the direction of motion. Thanks!
(Score: 0) by Anonymous Coward on Tuesday February 07 2017, @07:35PM
Best SN post ever.
(Score: 2) by bob_super on Tuesday February 07 2017, @09:50PM
It ruins my "cruising the galaxy at warp speed" dreams (or nightmares, depending on the presence of particles in the way).
But it does save on food supplies if you arrive just as you leave.
(Score: 2) by JoeMerchant on Tuesday February 07 2017, @11:45PM
Acceleration to, and deceleration from, the speed of light can be a little rough if you do it in a reasonable amount of time.
🌻🌻 [google.com]
(Score: 2) by wonkey_monkey on Tuesday February 07 2017, @05:59PM
Although all the numbers up to the speed of light certainly point in that direction, apparently it's not de rigueur to say such a thing these days. Instead, photons just don't have frames of reference.
systemd is Roko's Basilisk
(Score: 2) by maxwell demon on Tuesday February 07 2017, @06:46PM
That argument is basically the argument that just because you can divide by an arbitrary small positive number, you should also be able to divide by zero.
Note that this is not just an analogy; if you try to actually describe a frame of reference for the photon, you will need to divide by zero.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by wonkey_monkey on Tuesday February 07 2017, @07:56PM
But describing the proper time, at least, of faster particles involves multiplying by increasingly small numbers, and we know exactly what happens when you multiply by zero.
systemd is Roko's Basilisk