Up, down, round and round

I recall seeing a comic strip a while back making fun of one of the features of Star Trek that doesn't seem ridiculous until you think about it a little.  Have you noticed that whenever two starships are near each other -- whether it's the Enterprise and other Federation ships, or they're being threatened by the Romulans or Klingons or whatnot -- the ships are almost always oriented the same way?  The only time this is not the case is when the showrunner wanted to make it clear that the other ship was disabled and drifting.  Then it was shown at some odd angle relative to the Enterprise.  In the comic strip, it showed what it would look like if all the ships were at random orientations -- how ridiculous it appeared -- but really, isn't that what you'd expect?  In the Star Trek universe, each ship is supposed to come with its own artificial gravity, so within any ship, up is "toward the ceiling" and down is "toward the floor."  It wouldn't need to line up with any other ship's artificial gravity, so except for an occasional coincidence, they should all be at various angles.

In space, there's no preferred direction, no "up" or "down."  You always have to describe position relative to something else -- to the axis of the Earth's rotation, or the plane of the Solar System, or the plane of revolution of the Milky Way.  But even those aren't some kind of universal orientation; as I described in a recent post, the universe is largely isotropic (the same in every direction).  Just like the starships in Star Trek, there shouldn't be any preferred directionality.

Well, that's what we thought.

A new paper this week in the journal Monthly Notices of the Royal Astronomical Society describes a set of data from the James Webb Space Telescope that is absolutely astonishing.  Here's how the authors describe it:

JWST provides a view of the Universe never seen before, and specifically fine details of galaxies in deep space.  JWST Advanced Deep Extragalactic Survey (JADES) is a deep field survey, providing unprecedentedly detailed view of galaxies in the early Universe.  The field is also in relatively close proximity to the Galactic pole.  Analysis of spiral galaxies by their direction of rotation in JADES shows that the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way.  The analysis is done using a computer-aided quantitative method, but the difference is so extreme that it can be noticed and inspected even by the unaided human eye.  These observations are in excellent agreement with deep fields taken at around the same footprint by Hubble Space Telescope and JWST.

This adds a whole new twist (*rimshot*) to the horizon problem and the isotropy of the universe as a whole.  Not only do we have the issue that causally-disconnected regions of the cosmic microwave background radiation, that are too far apart to have ever influenced each other (something I describe more fully in the above-linked post), are way more similar in temperature than you'd expect -- now we have to figure out how causally-disconnected galaxies on opposite sides of the universe could possibly have ended up with correlated rotational axes.

The authors admit it's possible that this measurement is due to something about the Milky Way's own rotation that we're not compensating for in the data, but there's a more out-there explanation that the paper's authors are seriously considering.

"It is not clear what causes this to happen," said study co-author Lior Shamir, of Kansas State University, in an interview with Independent.  "[But] one explanation is that the universe was born rotating.  That explanation agrees with theories such as black hole cosmology, which postulates that the entire universe is the interior of a black hole."

Black holes are defined by three properties -- mass, electric charge, and... angular momentum.  That we're inside a rotating black hole would explain the anomaly JWST just observed.  Since -- at least as far as our current understanding goes -- anything inside a black hole's event horizon is forever inaccessible, perhaps this means that event horizons are boundaries between universes.  As bizarre as that sounds, there is nothing about what we know of the laws of physics and cosmology that rules that out.  Which would mean that...

... black holes are bigger on the inside.

The Doctor tried to tell us.

Of course, the more prosaic explanation -- that the data were somehow influenced by our own motion through space -- has yet to be decisively ruled out.  I can't help but feel, though, that if the authors thought that was likely, they (or their reviewers) would have suggested waiting and re-analyzing before publishing in a prestigious journal like MNRAS.  The greater likelihood is that this is a real signal, and if so, it's mighty odd.

As far as what it would mean if we found out we are inside a black hole, well -- I'm hardly qualified to weigh in.  It probably wouldn't affect our day-to-day life any.  After all, it's not like we were going to find a way out of the universe anyhow, much as recent events here on Earth have made many of us wish we could.  All I can say is stay alert for further developments, and keep looking up.

Whatever direction that actually is.

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Lost horizon

While our knowledge of the origin of the universe has grown tremendously in the past hundred years, there are still plenty of cosmological mysteries left to solve.

One of the most vexing is called the horizon problem.

It's one of those situations where at first, it seems like "where's the problem?"  Then you look into it a little more, and kind of go, "... oh."  The whole thing has to do with how fast a change can percolate through a system.  Amongst the (many) outcomes of the General Theory of Relativity, we are reasonably certain that the upper bound at which disturbances of any kind can propagate is the speed of light.

So if a change of some sort happens in region A, but it is so far away from region B that there hasn't been enough time for light to travel between the two, it is fundamentally impossible for that change to have any effect at all in region B.  Such regions are said to be causally disconnected.

So far, so good.  The thing is, though, there are plenty of sets of causally disconnected regions in the universe.  If at midnight in the middle of winter you were to aim a very powerful telescope straight up into the sky, the farthest objects you could see are on the order of ten billion light years away.  Do the same six months later, in midsummer, and you'd be looking at objects ten billion light years away in the other direction.  The distance between the two is therefore on the order of twenty billion light years (and this is ignoring the expansion of the universe, which makes the problem even worse).  Since the universe is only something like 13.8 billion years old, there hasn't been enough time for light to travel between the objects you saw in winter and those you saw in summer.

Therefore, they can't affect each other in any way.  Furthermore, they've always been causally disconnected, at least as far back as we have good information.  By our current models, they were already too far apart to communicate three hundred thousand years after the Big Bang, the point at which decoupling occurred and the 2.7 K cosmic microwave background radiation formed. 

Herein lies the problem.  The cosmic microwave background (CMB for short) is very nearly isotropic -- it's the same no matter which direction you look.  There are minor differences in the temperature, thought to be due to quantum fluctuations at the moment of decoupling, but those average out to something very close to uniformity.  It seems like some process homogenized it, a bit like stirring the cream into a cup of coffee.  But how could that happen, if opposite sides of the universe were already causally disconnected from each other at the point when it formed?

A map of the CMB from the Wilkinson Microwave Anisotrophy Probe [Image is in the Public Domain courtesy of NASA]

It's worse still, however, which I just found out about when I watched a video by the awesome physicist and science educator Sabine Hossenfelder a couple of days ago.  Because a 2003 paper found that the CMB isn't isotropic after all.

I'm not talking about the CMB dipole anisotropy -- the fact that one region of the sky has CMB a little warmer than average, and the opposite side of the sky a little cooler than average.  That much we understand pretty well.  The Milky Way Galaxy is itself moving through space, and that creates a blue shift on one side of the sky and a red shift on the other, accounting for the measurably warmer and cooler regions, respectively.

What Hossenfelder tells us about is that there's an anisotropy in the sizes of the warm and cool patches.  It's called the hemispherical power spectrum asymmetry, and simply put, if you sort out the sizes of the patches at different temperatures, you find that one side of the sky is "grainier" than the other.  Like I said, we've known about this since 2003, but there was nothing in any of the models that could account for this difference, so cosmologists kind of ignored the issue in the hopes that better data would make the problem go away.

It didn't.  A recent paper using newly-collected data from the Planck mission found that the hemispherical power spectrum asymmetry is real.

And we haven't the first idea what could have caused it.

In a way, of course, this is tremendously exciting.  A great many scientific discoveries have started with someone looking at something, frowning, and saying, "Okay, hang on a moment."  Here we have something we already didn't understand (CMB isotropy and the horizon problem) gaining an added layer of weirdness (it's not completely isotropic after all, but is anisotropic in a really strange way).  What this shows us is that our current models of the origins of the universe are still incomplete.

Looks like it's a good time to go into cosmology.  In what other field is there a universe-sized problem waiting to be solved?

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The unbalanced universe

In her brilliant 2011 TED Talk "On Being Wrong," journalist Kathryn Schulz said, "For good and for ill, we generate these incredible stories about the world around us, and then the world turns around and astonishes us."

That astonishment is at the root of scientific discovery.  Many laypeople have the sense that scientists do what they do by patiently adding data bit by bit, assembling a theory from the results of experiment -- less understood is the fact that much of the time, the experiments themselves happened because of something unexpected that the old model couldn't explain.  It's those moments of, "Hey, now, wait a moment..." that have generated some of the most fundamental theories we have -- universal gravitation, relativity (special and general), evolution, genetics, plate tectonics.

Or, as another luminary of the philosophy of science put it -- James Burke, in his brilliant documentary series The Day the Universe Changed -- "The so-called voyage of discovery has, as often as not, made landfall for reasons little to do with the search for knowledge...  As far as one discovery following another along the way as part of some grand plan, what way?  Going where?"

Now, this is not to say that the lazy student's complaint, "why should we learn science, since it could all be proven wrong tomorrow?", has much merit.  The big ideas, like the ones I listed before, have been so extensively tested that it's unlikely they'll change much.  Any refinements will most probably be on the level of details.  Still... those head-scratching moments do occur, and sometimes they result in an overturning of what we thought we understood -- like the observation that was announced this week from NASA's Chandra X-ray Observatory.

[Image courtesy of NASA/Harvard University/Chandra X-ray Observatory]

One of the basic pieces of the Big Bang theory is that it resulted in a universe that is isotropic -- it basically looks the same no matter which direction you're looking.  The idea here is that when the universe began to expand, the fabric of space/time stretched out so much in the first tiny fraction of a second (something called cosmological inflation) that it resulted in a uniform, isotropic universe.

The analogy that's been around a long time to explain this -- I remember my college astronomy teacher using it, back in the early 1980s -- is to picture yourself as a tiny person, standing on one dot of a deflated polka-dotted balloon.  If the balloon is inflated, you see all the other dots moving away from you, regardless of which dot you're standing on; and in every direction, the dot-density is pretty much the same.  "There is no center of the universe," I recall our professor, Dr. Daniel Whitmire, saying.  "Or, perhaps, everywhere is the center.  It means essentially the same thing."

So the idea of isotropy is pretty deeply built into the Big Bang cosmology.  So the observation from Chandra announced this week that the universe seems to be anisotropic was a little startling, to say the least.

"Based on our cluster observations we may have found differences in how fast the universe is expanding depending on which way we looked," said study co-author Gerrit Schellenberger of the Center for Astrophysics of Harvard University.  "This would contradict one of the most basic underlying assumptions we use in cosmology today."

Or, as Konstantinos Migkas of the University of Bonn in Germany, who led the new study, put it, "One of the pillars of cosmology... is that the universe is 'isotropic....'   Our work shows there may be cracks in that pillar."

It's possible that the measurement doesn't mean what it seems to mean.  One possibility the researchers came up with that would be less-than-earthshattering is that some of the distant clusters might be moving together because of the gravitational pull of an unseen massive object or objects, throwing off the data enough to make it look like an anisotropy.  Another possibility -- which in my mind raises more questions than it solves -- is that the hypothesized "dark energy" that makes up three-quarters of the energy density of the universe is unevenly distributed, meaning its repulsive force is greater in some places than in others.  "This would be like if the yeast in the bread isn't evenly mixed, causing it to expand faster in some places than in others," said study co-author Thomas Reiprich, also of the University of Bonn, adding, "It would be remarkable if dark energy were found to have different strengths in different parts of the universe."

Remarkable especially since we still basically have no idea what dark energy is.  Going from there to any kind of cogent explanation of why there's more of it here than there seems to me to be a significant leap.

Or, perhaps, none of those is correct, and the anisotropy was built-in at the moment of the Big Bang by some process we haven't even dreamed of.

Whatever it turns out to be, this seems to me to be one of those "wait a moment..." discoveries that could potentially lead to a major revision of what we thought we knew.  What's certain is that it demonstrates how far we have to go in science -- and despite our progress, to paraphrase Kathryn Schulz, the universe will time after time turn around and astonish us.

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This week's Skeptophilia book recommendation of the week is brand new -- only published three weeks ago.  Neil Shubin, who became famous for his wonderful book on human evolution Your Inner Fish, has a fantastic new book out -- Some Assembly Required: Decoding Four Billion Years of Life, from Ancient Fossils to DNA.

Shubin's lucid prose makes for fascinating reading, as he takes you down the four-billion-year path from the first simple cells to the biodiversity of the modern Earth, wrapping in not only what we've discovered from the fossil record but the most recent innovations in DNA analysis that demonstrate our common ancestry with every other life form on the planet.  It's a wonderful survey of our current state of knowledge of evolutionary science, and will engage both scientist and layperson alike.  Get Shubin's latest -- and fasten your seatbelts for a wild ride through time.

Paradoxes within paradoxes

Sometimes the simplest, most innocuous-seeming questions can lead toward mind-blowingly profound answers.

I remember distinctly running into one of these when I was in -- I think -- 8th grade science class.  It was certainly pre-high-school; whether it was from Mrs. Guerin at Paul Breaux Junior High School, or another of my teachers, is a memory that has been lost in the sands of time and middle-aged forgetfulness.

What I have never forgotten is the sudden, pulled-up-short response I had to what has been nicknamed Olbers' Paradox, named after 18th century German astronomer Heinrich Wilhelm Matthias Olbers, who first thought to ask the question -- if the universe is infinite, as it certainly seems to be, why isn't the night sky uniformly and dazzlingly bright?

I mean, think about it.  If the universe really is infinite, then no matter what direction you look, your line of sight is bound to intersect with a star eventually.  So there should be light coming from every direction at once, and the night sky shouldn't be dark.  Why isn't it?

The first thought was that there was something absorptive in the way -- cosmic dust, microscopic or submicroscopic debris left behind by stars and blown outward by stellar wind.  The problem is, there doesn't seem to be enough of it; the average density of cosmic dust in interstellar space is less than a millionth of a gram per cubic meter.

When the answer was discovered, it was nothing short of mind-boggling.  It turns out Olbers' paradox isn't a paradox at all, because there is light coming at us from all directions, and the night sky is uniformly bright -- it's just that it's shining in a region of the spectrum our eyes can't detect.  It's called the three-degree cosmic microwave background radiation, and it appears to be pretty well isotropic (at equal intensities no matter where you look).  It's one of the most persuasive arguments for the Big Bang model, and in fact what scientists have theorized about the conditions in the early universe added to what we know about the phenomenon of red-shifting (the stretching of wavelengths of light if the space in between the source and the detector is expanding) gives a number that is precisely what we see -- light peaking at a wavelength of around one millimeter (putting it in the microwave region of the spectrum) coming from all directions.

[Image licensed under the Creative Commons Original: Drbogdan Vector: Yinweichen, History of the Universe, CC BY-SA 3.0]

So, okay.  Olbers' paradox isn't a paradox, and its explanation led to powerful support for the Big Bang model.  But in science, one thing leads to another, and the resolution of Olbers' paradox led to another paradox -- the horizon problem.

The horizon problem hinges on Einstein's discovery that nothing, including information, can travel faster than the speed of light.  So if two objects are separated by a distance so great that there hasn't been time for light to travel from one to the other, then they are causally disconnected -- they can't have had any contact with each other, ever.

The problem is, we know lots of such pairs of objects.  There are quasars that are ten billion light years away -- and other quasars ten billion light years away in the opposite direction.  Therefore, those quasars are twenty billion light years from each other, so light hasn't had time to travel from one to the other in the 13.8 billion years since they were created.

Okay, so what?  They can't talk to each other.  But it runs deeper than that.  When the aforementioned cosmic microwave background radiation formed, on the order of 300,000 years after the Big Bang, those objects were already causally disconnected.  And the process that produced the radiation is thought to have been essentially random (it's called decoupling, and it occurred when the average temperature of the universe decreased enough to free photons from the plasma and send them streaming across space).

The key here is the word average.  Just as a microwaved cup of coffee could have an average temperature of 80 C but have spots that are cooler and spots that are hotter, the fact that the average temperature of the universe had cooled sufficiently to release photons doesn't mean it happened everywhere simultaneously, leaving everything at exactly the same temperature.  In fact, the great likelihood is that it wouldn't.  And since at that point there were already causally disconnected regions of space, there is no possible way they could interact in such a way as to smooth out the temperature distribution -- sort of like what happens when you stir a cup of coffee.

And yet one of the most striking things about the cosmic microwave background radiation is that it is very nearly isotropic.  The horizon problem points out how astronomically unlikely that is (pun intended) if our current understanding is correct.

One possible explanation is called cosmic inflation -- that a spectacularly huge expansion, in the first fraction of a second after the Big Bang, smoothed out any irregularities so much that everywhere did pretty much decouple at the same time.    The problem is, we still don't know if inflation happened, although work by Alan Guth (M.I.T.), Andrei Linde (Stanford), and Paul Steinhardt (Princeton) has certainly added a great deal to its credibility.

So as is so often the case with science, solving one question just led to several other, bigger questions.  But that's what's cool about it.  If you're interested in the way the universe works, you'll never run out of things to learn -- and ways to blow your mind.

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This week's Skeptophilia book recommendation is one of personal significance to me -- Michael Pollan's latest book, How to Change Your Mind.  Pollan's phenomenal writing in tours de force like The Omnivore's Dilemma and The Botany of Desire shines through here, where he takes on a controversial topic -- the use of psychedelic drugs to treat depression and anxiety.

Hallucinogens like DMT, LSD, ketamine, and psilocybin have long been classified as schedule-1 drugs -- chemicals which are off limits even for research except by a rigorous and time-consuming approval process that seldom results in a thumbs-up.  As a result, most researchers in mood disorders haven't even considered them, looking instead at more conventional antidepressants and anxiolytics.  It's only recently that there's been renewed interest, when it was found that one administration of drugs like ketamine, under controlled conditions, was enough to alleviate intractable depression, not just for hours or days but for months.

Pollan looks at the subject from all angles -- the history of psychedelics and why they've been taboo for so long, the psychopharmacology of the substances themselves, and the people whose lives have been changed by them.  It's a fascinating read -- and I hope it generates a sea change in our attitudes toward chemicals that could help literally millions of people deal with disorders that can rob their lives of pleasure, satisfaction, and motivation.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Condensation and inflation

Online Critical Thinking course -- free for a short time!

This week, we're launching a course called Introduction to Critical Thinking through Udemy!  It includes about forty short video lectures, problem sets, and other resources to challenge your brain, totaling about an hour and a half.  The link for purchasing the course is here, but we're offering it free to the first hundred to sign up!  (The free promotion is available only here.)  We'd love it if you'd review the course for us, and pass it on to anyone you know who might be interested!

Thanks!

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I still recall my astonishment when one of my physics professors in college said, "We understand the physics of the universe fairly well back to about one-trillionth of a second after the Big Bang.  Before that, though, things are a little dicey."

To me, that sounded like having a pretty good handle on things, but that first one-trillionth of a second was pretty spectacular.  There were some extraordinary things going on very early along in that tiny time span -- from about 10⁻³⁶ to sometime between 10⁻³³ and 10⁻³² seconds after the initial singularity.  For those of you who are not mathematical types, this is the time between:

0.000000000000000000000000000000000001 seconds, and

0.0000000000000000000000000000001 seconds following the Big Bang.

This era is called the "inflationary period," a term that was coined by Alan Guth (then at Cornell) and Andrei Linde of Stanford, way back in 1979, who were investigating the question of why there are no magnetic monopoles (magnetic particles with only a north or south pole, but not both) and stumbled upon a phenomenon called a false vacuum that accounted for the known properties of matter and the universe.  The problem was, the mathematics of the false vacuum required a period extremely early on in the universe's history when it underwent exponential expansion.  If you thought the time duration of inflation defied the imagination, the size expansion is worse -- in that minuscule fraction of a second, the universe increased in volume by a factor of 10⁷⁸ -- one followed by 78 zeroes.

(Regular readers of Skeptophilia may remember that a while back, I wrote about a rather hysterical article that was making the rounds, speculating about the likelihood of our false vacuum state being superseded by a true vacuum -- which would rapidly destroy the entire universe.  The general conclusion of the physicists is that the risk of this is close enough to zero that you shouldn't be losing any sleep over it.)

[Image licensed under the Creative Commons Original: Drbogdan Vector: Yinweichen, History of the Universe, CC BY-SA 3.0]

As crazy as this sounds, it's been borne up by the evidence.  The vast majority of the research done on this topic is far beyond me even considering my B.S. in physics, but suffice it to say that most physicists accept inflation as a reality.  It accounts for a number of interesting phenomena, including isotropy -- that the universe looks homogeneous no matter what direction you look, which begs an explanation unless you think that the Earth is located in the dead center of the universe, a possibility that is even less than our risk of being destroyed by a true vacuum.  So it may sound hard to believe, but apparently, this enormous expansion in an unimaginably tiny fraction of a second actually happened.

Just last week there was another piece of evidence added to all of this, wherein scientists at the University of Maryland created a peculiar form of matter called a Bose-Einstein condensate that exhibited the properties of cosmic inflation, albeit (and fortunately) on a much smaller scale.  Emily Conover, over at Science News, describes the experiment as follows:

Shaped into a tiny, rapidly expanding ring, the condensate grew from about 23 micrometers in diameter to about four times that size in just 15 milliseconds.  The behavior of that widening condensate re-created some of the physics of inflation, a brief period just after the Big Bang during which the universe rapidly ballooned in size (SN Online: 12/11/13) before settling into a more moderate expansion rate. 

In physics, seemingly unrelated systems can have similarities under the hood. Scientists have previously used Bose-Einstein condensates to simulate other mysteries of the cosmos, such as black holes (SN: 11/15/14, p. 14).  And the comparison between Bose-Einstein condensates and inflation is particularly apt: A hypothetical substance called the inflaton field is thought to drive the universe’s extreme expansion, and particles associated with that field, known as inflatons, all take on the same quantum state, just as atoms do in the condensate.

Another point in favor of this research having recreated on some level the early expansion of the universe is that sound waves sent through the condensate increased in wavelength -- just as light has been red-shifted by the expansion of the space it's traveling through.

I'd be lying if I said I understood last week's paper on anything but the most rudimentary level, but it still gives me a sense of wonder that we can peer into the distant past -- into a time that lasted almost no time at all -- and use that information to draw conclusions about why the universe has the properties it does.   The progress we've made in expanding scientific understanding, in just the last twenty years, is mind-boggling.

All of which makes me wonder what the next twenty years will bring.  I'm hoping it's a warp drive, but that might be a forlorn hope, given that the General Theory of Relativity is strictly enforced in most jurisdictions.

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This week's featured book is a wonderful analysis of all that's wrong with media -- Jamie Whyte's Crimes Against Logic: Exposing the Bogus Arguments of Politicians, Priests, Journalists, and Other Serial Offenders.  A quick and easy read, it'll get you looking at the nightly news through a different lens!