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All Disk Galaxies Rotate Once Every Billion Years (astronomy.com)
According to a new study published in The Monthly Notices of the Royal Astronomical Society, astronomers discovered that all disk galaxies rotate about once every billion years, no matter their size or mass. Astronomy Magazine reports: To carry out the study, the researchers measured the radial velocities of neutral hydrogen in the outer disks of a plethora of galaxies -- ranging from small dwarf irregulars to massive spirals. These galaxies differed in both size and rotational velocity by up to a factor of 30. With these radial velocity measurements, the researchers were able to calculate the rotational period of their sample galaxies, which led them to conclude that the outer rims of all disk galaxies take roughly a billion years to complete one rotation. However, the researchers note that further research is required to confirm the clock-like spin rate is a universal trait of disk galaxies and not just a result of selection bias. Based on theoretical models, the researchers also expected to find only sparse populations of young stars and interstellar gas on the outskirts of these galaxies. But instead, they discovered a significant population of much older stars mingling with the young stars and gas.
That's interesting.
OK, but why? It seems counter-intuitive that dense galaxies and sparse galaxies, big galaxies and small galaxies, would all rotate at roughly the same speed. The astronomy.com article is light on details and the Royal Astronomical Society's abstract is somewhat incomprehensible to a layman like myself.
Can someone explain?
TFS oversimplifies things a bit. The finding is that the outer edge of these galaxies rotates at about the same rate for all of them. That's not entirely surprising: the more massive the galaxy, the faster the rotation at any given distance, but also the more distant the outer rim. It also implies a similar ration of dark matter to familiar matter across these galaxies - which again isn't shocking, but is interesting if the ration has to be very similar. If it's confirmed they really do line up this closely that's probably big news for those modelling galaxy formation.
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Think about what they are saying for a moment ...
No matter how big the black hole is, no matter how much matter is in the galaxy, no matter how much dark matter might exist, no matter when the black hole formed, and regardless of the unique histories we observe each of these galaxies to have had ...
... they all rotate at the same rate.
Here's the thought you did not have, but should have:
If each of these galaxies is connected with one another through the jets we sometimes see coming out of them, then one reasonable way to explain this very strange observation is if it is the jets that are driving all of the galaxies, rather than the reverse.
Like many others, this observation can be called a vindication for the idea that electricity in space -- the jets -- actually does things of importance at the cosmological scales.
But, also notice that you did not recognize this on your own. It took somebody else tracking the controversy to see it and inform you. When the world convinces itself that it does not need to track "settled science" claims, there is no doubt that things are going to fall through the cracks.
Okay, so the larger the galaxy, the faster it must spin to complete a rotation in the same time as a smaller galaxy. The more mass a galaxy has means more for dark matter to gravitationally interact with it.. could it be repelling it somehow in order to accelerate it? Or attracting it?
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When bringing up the simulation a single rotation rate variable was used as a temporary hack. It was mean to be replaced with a per-galaxy value before release, but it slipped through.
Whenever I find the same outcomes produced with different variables I tend to suspect my observation method.
Quantum theory expresses the concept that every particle, every wave, every speck of anything is potentially everywhere in space and time, and all but one of these potentials cancel each other out. Perhaps, through some strange calamity, all of these galaxies are simply the same potential galaxy in different places within space and time because some of the potentials were destroyed, thus allowing the other potentials they should cancel out to be observable from other potentials.
Or, perhaps, I need another hit.
It is an EXCEEDINGLY strange coincidence if this proves to be true. To strange to be coincidence, frankly. There has to be some cosmic cause, and I'd bet dollars to donuts (Mmmmm donuts) that there's something involving quantum mechanics or quantum physics that causes this.
i mean really,
#define kGALAXY_ROT_SPD 1000000000
?
Well, I am sure you can find a spot or a metric where the numbers fit, like the researchers here did, but galaxies are not rigid and thus does not have a constant rotations per billion year for every part of it.
"... researchers measured the radial velocities ..." ..."
"... they discovered a significant population of much older stars
The simulation only served to create a hypothesis which was disproved. You know, by science. That thing that you apparently don't know very well.
And here I though the rotation of our own galaxy had a period more on the order of a quarter billion years. Has this assumption changed? Or is the Milky Way (a barred spiral) not considered a disk galaxy?
Or is that just the rotation rate out where we are (an unfashionable district of the western spiral arm), and the rim takes longer?
In addition to selection bias, as the summary noted, there is also the matter of sample size, compared to the entire universe. The margin of error would have to be very large.
Also, can one really estimate motion in terms of billion-year cycles from studies conducted over, at most, a few years?
Obviously the Intergalactic Police are making sure they do not travel faster than the posted galactic speed limit.
That planetary systems are just like atoms and molecules and rotation speeds and energy transfers are happening the same way, even though we haven't connected the dots yet.
Obviously this would require a lot of observations and math I have neither time, mathematical skill, nor interest in, but it makes for an interesting thought experiment, especially when you add in the concept of multiverses and each existing inside of some form of matter inside of another universe, such that they are all interconnected and existing inside of each other.
It all has to do with Gravity, once we figure that out then the rest will fall into place.
Does the universe rotate around the point where the Big Bang happened?
That existence is pretty much what I am expecting some scientist to figure out a long time from now, get supremely depressed, and end it all taking his secrets with him.
So we tell time?
Well no, the Universe tells time, you do practically nothing.
What does he use it for? Wouldn't he always know what time it is?
Mostly just as an accessory, he likes how it looks. I mean you have an iPhone don't you?
Oh my God.
Exactly.
Galaxies are indeed not rigid disks, but the remarkable thing is that your garden-variety spiral galaxy behaves much more like a rigid disk than your angular-momentum-conserving bathtub drain. These rotation rates, by the way, are measured using the Doppler shift observed in spectrographic observations of those galaxies.
It is hypothesized that the "halo" of a spiral galaxy must either contain considerable unobserved "dark matter" or Newton's laws of acceleration and gravitation need a correction term. Most astrophysicists base their work on the Dark Matter explanation, but there are holdouts for MOND (Modified Newtonian Dynamics). So yes, the outer portions of a spiral galaxy have nearly the same rate of angular rotation as in the inner parts, and physical theory needs to account for this conundrum.
"But instead, they discovered a significant population of much older stars mingling with the young stars and gas."
Sounds like an Oscars after-party.
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