The cosmic Tilt-O-Whirl

Anybody have any ideas about what this is?

I've shown a bunch of people, and I've gotten answers from an electron micrograph of a sponge to a close-up of a block of ramen to the electric circuit diagram of the Borg Cube.  But the truth is almost as astonishing:

It's a map of the fine structure of the entire known universe.

Most everyone knows that the stars are clustered into galaxies, and that there are huge spaces in between one star and the next, but far bigger ones between one galaxy and the next.  Even the original Star Trek got that right, despite their playing fast and loose with physics every episode.  (Notwithstanding Scotty's continual insistence that you canna change the laws thereof.)  There was an episode called "By Any Other Name" in which some evil aliens hijack the Enterprise so it will bring them back to their home in the Andromeda Galaxy, a trip that will take three hundred years at Warp Factor Ten.  (And it's mentioned that even that is way faster than a Federation starship could ordinarily go.)

So the intergalactic spaces are so huge that they're a bit beyond our imagining.  But if you really want to have your mind blown, consider that the filaments of the above diagram are not streamers of stars but streamers of galaxies.  Billions of them.  On the scale shown above, the Milky Way and the Andromeda Galaxy are so close as to be right on top of each other.

What is kind of fascinating about this diagram -- which, by the way, is courtesy of NASA/JPL -- is not only the filaments, but the spaces in between them.  These "voids" are ridiculously huge.  The best-studied is the Boötes Void, which is centered seven hundred million light years away from us.  It is so big that if the Earth were at the center of it, we wouldn't have had telescopes powerful enough to see the nearest stars until the 1960s, and the skies every night would be a uniform pitch black.

That, my friends, is a whole lot of nothing.

The reason all this comes up is a paper that appeared last week in Monthly Notices of the Royal Astronomical Society about some research out of Cambridge and Oxford Universities into the structure of one of those cosmic filaments, which found that it shows some pretty peculiar properties.  The particular filament studied is "only" about 450 million light years away -- for reference, that's about two hundred times farther than the Andromeda Galaxy -- and contains just shy of three hundred galaxies.

Astronomers can now make amazingly accurate determinations of the rotational speed and direction of galaxies, despite the distances involved and the fact that galaxies are enormous enough that on a human timescale, you can't see the individual stars moving.  They use the Doppler effect -- the fact that if you're looking at a rotating galaxy (especially one that's edge-on), half the stars are moving away from us and half are moving towards us.  This means that the first bunch have their light stretched out (red-shifted) and the others have their light compressed (blue-shifted).  From the light coming from the center, you can tell what the galaxy's overall motion is with respect to us, so voilà -- you have the rotational speed and overall linear velocity.

I mean, it's not as simple as I'm making it sound in practice, but the principle is actually relatively straightforward.

And what they found is that within this filament, the individual galaxies are all rotating in approximately the same plane, and the filament as a whole is rotating -- in the same direction.

"What makes this structure exceptional is not just its size, but the combination of spin alignment and rotational motion," said co-lead author Dr. Lyla Jung, of the University of Oxford, in a press release.  "It’s like the teacups ride at a theme park.  Each galaxy is like a spinning teacup, but the whole platform -- the cosmic filament -- is rotating too.  This dual motion gives us rare insight into how galaxies gain their spin from the larger structures they live in."

It's kind of dizzying to think about, isn't it?  We're on a spinning globe, whirling in orbit around a star; the star, and its attendant planets and other oddments, are sitting in the spiral arm of a galaxy that is itself rotating at a breakneck speed; the entire "Local Group" of galaxies is spinning, too; and the Laniakea Supercluster, to which the Local Group and about a hundred thousand galaxies belongs, is zooming toward an unseen point called the "Great Attractor" about whose nature we haven't the first clue.  Now, we find that in addition to all this, each strand in the spiderweb of galaxy clusters that spans the entire cosmos is itself rotating, and has imparted that rotational direction to the galaxies within it.

I'm getting vertigo just thinking about it.

So think about this the next time you're tempted to say you're "going nowhere fast."  You're definitely going somewhere.  Really quickly.  In fact, the entire universe is kind of like a giant Tilt-O-Whirl.

Hope you don't suffer from motion sickness.

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Reversing the core

I get really frustrated with science news reporting sometimes.

I mean, on the one hand, it's better that laypeople get exposed to science somehow, instead of the usual fare of the mainstream media, which is mostly stories about seriously depressing political stuff and the latest antics of celebrities.  But there's a problem with science reporting, and it's the combination of a lack of depth in understanding by the reporters, and a more deliberate desire to create clickbaity headlines and suck people in.

Take, for example, the perfectly legitimate (although not universally accepted) piece of research that appeared on January 23 in Nature Geoscience, suggesting that the Earth's inner core oscillates in its rotational speed with respect to the rest of the planet -- first going a little faster, then slowing a bit until its rotational rate matches Earth's angular velocity, then slowing further so the rest of the planet for a time outruns the core.  Then it speeds up, and does the whole thing in reverse.  The reason -- again, if it actually happens, which is still a matter of discussion amongst the experts -- is that the speed-up/slowdown occurs because of a combination of friction with the outer core, the effects of the magnetic field, and the pull of gravity from the massive mantle that lies outside it.

[Image licensed under the Creative Commons CharlesC, Earth cutaway, CC BY-SA 3.0]

That's not how this story got reported, though.  I've now seen it several times in different mainstream media, and universally, they claim that what's happening is that the inner core has stopped, and started to spin the other way -- i.e. the inner core is now rotating once a day, but in the opposite direction from the rest of the Earth.

This is flat-out impossible.  Let's start with the fact that the inner core has a mass of about 110,000,000,000,000,000,000,000 kilograms.  A mass that huge, spinning on its axis once a day, has a stupendous amount of angular momentum.  To stop the rotation of that humongous ball of nickel and iron would take an unimaginable amount of torque, and that's not even counting overcoming the drag that would be exerted by the outer core as you tried to make the inner core slow down.  (I could calculate how much, but it's just another huge number and in any case I don't feel like it, so suffice it to say it's "a shitload of torque.")  Then, to accelerate it so it's rotating at its original rate but in the opposite direction would take that much torque again.

Where's the energy coming from to do all that?

Here, the fault partly lies with the scientists; they did use the words "reversing direction" in their press release, but what they meant was "reversing direction with respect to the motion of the rest of the Earth."  I get that relative motion can be confusing to visualize -- but giving people the impression that something has stopped the inner core of the Earth and started it rotating in the opposite direction gives new meaning to "inaccurate reporting."

Worse still, I'm already seeing the woo-woos latch onto this and claim that it's a sign of the apocalypse, that the Evil Scientists™ are somehow doing this deliberately to destroy the Earth, that it's gonna make the magnetic field collapse and trigger a mass extinction, and that it's why the climate has been so bonkers lately.  (Anything but blame our rampant fossil fuel use, apparently.)  Notwithstanding that if you read the actual paper, you'll find that (1) whatever this phenomenon is, it's been going on for ages, (2) it represents a really small shift in the inner core's angular velocity, and (3) it probably won't have any major effects on we ordinary human beings.  After all, (4) the scientists have only recently figured out it's happening, and (5) not all of them believe it is happening.

So let's just all calm down a bit, okay?

In any case, I'd really appreciate it if the people reporting science stories in the mainstream media would actually read the damn papers they're reporting on.  It'd make the job of us skeptics a hell of a lot easier.  Thanks bunches.

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