Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Pecos_Bill on 04/05/2014 03:11:37
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I am holding off dull times by classifying galaxies on "galaxy zoo"
Some spiral galaxies appear to spin counter clockwise and some clockwise. When I find one I tag it clockwise or anticlockwise.
Are some of them in looking class land with Alice and the red queen?
Is some cosmological Maxwell's demon at work?
Are they distributed equally in the observable universe or is there some anisotrophy?
Is galactic spin a cosmological coin flip?
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Clockwise vs Counterclockwise is just a matter of perspective. Look at a galaxy from above and it will appear to be rotating one direction. Look at it from below, and it will appear to be rotating the opposite direction.
Viewed from Earth, we can see other galaxies from either above, below, or to the edge (most would be at different angles than a perfect straight above/below). I'm not sure flipping a coin would explain it, but perhaps take a ball, paint the top half blue, the bottom half red, then roll it until it stops rolling, then observe which half/angle is facing towards you.
The Milky Way has a number of satellite galaxies. I'm not sure if their rotation would be affected by the Milky Way. I would almost expect those with a prograde orbit around the Milky Way to have a retrograde rotation, but don't have that data.
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With respect, I don't see it.
The Right hand rule would hold whether you were behind or in front of the hand.
I imagine a clockface behiind me constrained in 2 dimensions the hands moving clockwise. Now I move it before me without flipping it over and I see it from the back -- the hands are still going clockwise. Even if you flip it - it still has edither dextro or levo rotation doesn't it? In any case, are the galaxies tumbling? How could they remain planar if that were so?
Surely chirality is invariant throughout the universe. D-tyrosamine is still d-tyrosamine whether it is behind me or in front of me.
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I see a problem with the "Clock in front/clock behind" analogy: When you look at the clock behind you, the observer has to turn around, which reverses the apparent clockwise/counterclockwise direction. Galaxy Zoo (http://en.wikipedia.org/wiki/Galaxy_zoo#Discoveries) is only looking at galaxies "in front" of the telescope, so what happens "behind" the telescope doesn't really affect the outcome.
Perhaps a better clock analogy would be to take a clock in front of you, and spin it a random amount on X, Y & Z axes, then look at it and see if it is now rotating more clockwise or counterclockwise? (...or edge-on, in which case you can't tell the direction without doing something more sophisticated like measuring the red shift on the approaching/receding sides).
I imagine that a galaxy is like a giant gyroscope, which will continue spinning on the same axis unless affected by an external force. Such a force may occur if two galaxies collide, for example (or at least approach very closely).
One of the early discoveries of Galaxy Zoo was that there seemed to be a bias of clockwise vs counterclockwise spins, so they started randomly flipping the image before presenting it to the human volunteers for assessment. This removed this early orientation bias, and this is now thought to be a psychological artifact.
It is still possible that a number of galaxies which formed close together might take on an overall angular momentum that might have been present in the original gas/dust cloud.
However, if the distribution of globular clusters in our galaxy is any guide, our galaxy formed from the accretion of many smaller galaxies, with random initial axis of angular momentum, resulting in a galaxy today whose rotation axis bears little resemblance to the initial orientation.
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Thank you for your reply.
I haven't tallied, but it seems to me the sample I am running of about 1100 so far is pretty evenly distributed with clockwise vs. anticlockwise.
I am going to run a sample of 100 or so and see how it falls out.
There is something in Socrates about how we are all seeing reality as shadows on a cave wall instead of the bona fide real deal. Isn't t the truth!
I will come back in a skosh and let you know how it turns out.
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If you had a transparent clock, then looking at it from the back side, it would appear to run backwards.
Perhaps an easier way to look at it. Take your bicycle. Push it forward. Look at the wheel. When looking at the wheels from the right side, the forward moving wheels will appear to turn clockwise. On the other hand, looking from the left side, they will appear to turn counterclockwise. On cars, the wheel spindle nuts are often designed to rotate in the direction to tighten when driving forward, so the right is standard clockwise threads, the left uses left hand counterclockwise threads.
The gyroscope is an interesting question. Would the spin of the galaxy prevent it from rotating around the opposite axis? There would be at least a fair amount of axis stability, although gravitational interactions with neighboring galaxies may affect the rotation axis.
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the right [wheel] is standard clockwise threads, the left uses left hand counterclockwise threads
I hadn't noticed that - but then I haven't changed several wheels at once!
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the right [wheel] is standard clockwise threads, the left uses left hand counterclockwise threads
I hadn't noticed that - but then I haven't changed several wheels at once!
I meant the spindle nuts for the wheel bearings. Not the lug nuts.
However, some vehicles in the past did in fact use left handed lug nuts which are a pain if not expected.
"Knock-Offs" may also use left-handed threads, but may be on opposite sides of the car.
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Clockwise vs Counterclockwise is just a matter of perspective. Look at a galaxy from above and it will appear to be rotating one direction. Look at it from below, and it will appear to be rotating the opposite direction.
Viewed from Earth, we can see other galaxies from either above, below, or to the edge (most would be at different angles than a perfect straight above/below). I'm not sure flipping a coin would explain it, but perhaps take a ball, paint the top half blue, the bottom half red, then roll it until it stops rolling, then observe which half/angle is facing towards you.
The Milky Way has a number of satellite galaxies. I'm not sure if their rotation would be affected by the Milky Way. I would almost expect those with a prograde orbit around the Milky Way to have a retrograde rotation, but don't have that data.
This idea of perspective is what I don't understand after reading previous discussions on this topic. Shouldn't it be true that an "up" or "down" regardless of perspective could be determined if a galaxy has an observable, overreaching magnetic field beyond the many magnetic fields that make up a galaxy?
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The magnoflux spin effect will cause the spiral galaxies to shape up if they and magnetised by a common magnetic hub at the centre of the galaxy AKA super massive black hole.
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With respect, I don't see it.
The Right hand rule would hold whether you were behind or in front of the hand.
The right hand rule does not apply to the sense of rotation of a galaxy. The right hand rule only applies to scenarios in which two other vectors are already established and to which the third needs to have a particular direction selected out of the two choices. It does not apply to the rotation of a body. Using it as you did is like saying that the Earth is rotating clockwise. That's neither correct nor incorrect since you can just as easily have chosen a coordinate system in which it rotating counter clockwise. For example, the magnetic field encircling a current carrying wire has a direction which is determined by the direction of the current flow. One then needs the right hand rule in order to determine the direction of the magnetic field.
I imagine a clockface behiind me constrained in 2 dimensions the hands moving clockwise. Now I move it before me without flipping it over and I see it from the back -- the hands are still going clockwise. Even if you flip it - it still has edither dextro or levo rotation doesn't it? In any case, are the galaxies tumbling? How could they remain planar if that were so?
If that's the same way in which you view the rotation of galaxies then the same idea holds. There simply is no unique direction in which all galaxies rotated. If you wish to assign a particular direction to the direction of rotation, e.g. to have the same direction as the angular momentum, then the direction of angular momentum of all galaxies is random.
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If that's the same way in which you view the rotation of galaxies then the same idea holds. There simply is no unique direction in which all galaxies rotated. If you wish to assign a particular direction to the direction of rotation, e.g. to have the same direction as the angular momentum, then the direction of angular momentum of all galaxies is random.
Every particle has spin. Composite particles like atoms have a spin based on their components. When atoms get together to form a molecule, that molecule has an inherent spin that is a composite of the spins of the constituent atoms. So, I think it's possible that the rotation of stars and galaxies might be a remnant of or an evolved state derived from the inherent spins of the particles that make it up.
Do you think my premise for that argument is off base, or do you think there might be something to it?
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If that's the same way in which you view the rotation of galaxies then the same idea holds. There simply is no unique direction in which all galaxies rotated. If you wish to assign a particular direction to the direction of rotation, e.g. to have the same direction as the angular momentum, then the direction of angular momentum of all galaxies is random.
Every particle has spin. Composite particles like atoms have a spin based on their components. When atoms get together to form a molecule, that molecule has an inherent spin that is a composite of the spins of the constituent atoms. So, I think it's possible that the rotation of stars and galaxies might be a remnant of or an evolved state derived from the inherent spins of the particles that make it up.
Do you think my premise for that argument is off base, or do you think there might be something to it?
Yes, particles have "spin," but that has little (if anything) to do with actual spinning or rotating. It's just the word we use for a quantum mechanical parameter. As you put particles with spin together, those spins interact, usually such that they cancel each other out. For instance, electrons can be spin up or spin down, and they tend to pair up such that a molecule with an even number of electrons usually has a net spin of 0 (based on electron contribution). We call these molecules diamagnetic. There are some compounds that have an odd number of electrons or favor unpaired electrons, even if they could theoretically pair up. These molecules are paramagnetic. Paramagnetic species usually pair up with each other in the absence of other magnetic fields, such that their spins cancel out (antiferromagnetic), but they can also form additive conglomerates (ferromagnetic--this is usually what we call "magnetic" colloquially)
Protons and neutrons also typically add up such that their spins cancel out (essentially the same mechanisms as with electrons.) For instance, 12C is a spin 0 nucleus because the 6 protons and 6 neutrons perfectly cancel out. 13C can't do this because it has an odd number of nucleons, and therefore has a net spin of 1/2 (and is NMR active) 14N (with 7 protons and 7 neutrons) is unusual in that the spins align and form a spin 1 nucleus.
Overall, I think it is highly unlikely that the "spin" of subatomic particles has any substantial effect on the spin of galaxies. In the absence of a magnetic field, there is no reason spin up would be favored over spin down, or vice versa. Angular momentum is conserved, so one could, in principle, impart angular momentum of a whole galaxy by flipping the spins of its constituent particles (by some unknown mechanism), but aligning so many particles would be very much disfavored entropically...