A matter of scale

In Douglas Adams's brilliant book, The Hitchhiker's Guide to the Galaxy, a pair of alien races, the Vl'Hurg and the G'gugvuntt, spent millennia fighting each other mercilessly until they intercept a message from Earth that they misinterpret as being a threat.  They forthwith decide to set aside their grievances with each other, and team up for an attack on our planet in retaliation:

Eventually of course, after their Galaxy had been decimated over a few thousand years, it was realized that the whole thing had been a ghastly mistake, and so the two opposing battle fleets settled their few remaining differences in order to launch a joint attack on our own Galaxy...

For thousands more years the mighty ships tore across the empty wastes of space and finally dived screaming on to the first planet they came across -- which happened to be the Earth -- where due to a terrible miscalculation of scale the entire battle fleet was accidentally swallowed by a small dog.

I was reminded of the Vl'Hurg and G'gugvuntt while reading the (much more serious) book The View from the Center of the Universe, by physicist Joel Primack and author and polymath Nancy Abrams.  In it, they look at our current understanding of the basics of physics and cosmology, and how it intertwines with metaphysics and philosophy, in search of a new "foundational myth" that will help us to understand our place in the universe.

What brought up Adams's fictional tiny space warriors was one of the most interesting things in the Primack/Abrams book, which is the importance of scale.  There are about sixty orders of magnitude (powers of ten) between the smallest thing we can talk meaningfully about (the Planck length) and the largest (the size of the known universe), and we ourselves fall just about in the middle.  This is no coincidence, the authors say; much smaller life forms are unlikely to have to have the complexity to develop intelligence, and much larger ones would be limited by a variety of physical factors such as the problem that if you increase length in a linear fashion, mass increases as a cube.  (Double the length, the mass goes up by a factor of eight, for example.)  Galileo knew about this, and used it to explain why the shape of the leg bones of mice and elephants are different.  Give an animal the size of an elephant the relative leg diameter of a mouse, and it couldn't support its own weight.  (This is why you shouldn't get scared by all of the bad science fiction movies from the fifties with names like The Cockroach That Ate Newark.  The proportions of an insect wouldn't work if it were a meter long, much less twenty or thirty.)

Pic from the 1954 horror flick Them!

Put simply: scale matters.  Where it gets really interesting, though, is when you look at the fundamental forces of nature.  We don't have a quantum theory of gravity yet, but that hasn't held back technology from using the principles of quantum physics; on the scale of the very small, gravity is insignificant and can be effectively ignored in most circumstances.  Once again, we ourselves are right around the size where gravity starts to get really critical.  Drop an ant off a skyscraper, and it will be none the worse for wear.  A human, though?

And the bigger the object, the more important gravity becomes, and (relatively speaking) the less important the other forces are.  On Earth, mountains can only get so high before the forces of erosion start pulling them down, breaking the cohesive electromagnetic bonds within the rocks and halting further rise.  In environments with lower gravity, though, mountains can get a great deal bigger.  Olympus Mons, the largest volcano on Mars, is almost 22 kilometers high -- 2.5 times taller than Mount Everest.  The larger the object, the more intense the fight against gravity becomes.  The smoothest known objects in the universe are neutron stars, which have such immense gravity their topographic relief over the entire surface is on the order of a tenth of a millimeter.

Going the other direction, the relative magnitudes of the other forces increase.  A human scaled down to the size of a dust speck would be overwhelmed by electromagnetic forces -- for example, static electricity.  Consider how dust clings to your television screen.  These forces become much less important on a larger scale... whatever Gary Larson's The Far Side would have you believe:

Smaller still, and forces like the strong and weak nuclear forces -- the one that allows the particles in atomic nuclei to stick together, and the one that causes some forms of radioactive decay, respectively -- take over.  Trying to use brains that evolved to understand things on our scale (what we term "common sense") simply doesn't work on the scale of the very small or very large.

And a particularly fascinating bit, and something I'd never really considered, is how scale affects the properties of things.  Some properties are emergent; they result from the behavior and interactions of the parts.  A simple example is that water has three common forms, right?  Solid (ice), liquid, and gaseous (water vapor).  Those distinctions become completely meaningless on the scale of individual molecules.  One or two water molecules are not solid, liquid, or gaseous; those terms only acquire meaning on a much larger scale.

This is why it's so interesting to try to imagine what things would be like if you (to use Primack's and Abrams's metaphor) turned the zoom lens one way and then the other.  I first ran into this idea in high school, when we watched the mind-blowing short video Powers of Ten, which was filmed in 1968 (then touched up in 1977) but still impresses:

Anyhow, those are my thoughts about the concept of scale.  An explanation of why the Earth doesn't have to worry about either Vl'Hurgs and G'gugvuntts, enormous bugs, or static cling making your child stick to the ceiling.  A relief, really, because there's enough else to lose sleep over.  And given how quickly our common sense fails on unfamiliar scales, it's a good thing we have science to explain what's happening -- not to mention fueling our imaginations about what those scales might be like.

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A lens into the dark sector

I don't really regret the weird, meandering path I took through the educational system -- but I have to admit to a bit of envy when it comes to people who are true experts in their field.

My inveterate dilettantism means I'm reasonably conversant in a lot of areas, but don't really have a deep understanding of anything.  Being a dabbler is neither a bad background to have as a high school teacher nor as a blogger, but it does mean that I often run into topics and think, "Wow, I really wish I could wrap my brain around this."

This happened just yesterday when I happened upon a paper in The European Physical Journal C called, "A Warped Scalar Portal to Fermionic Dark Matter."  My Bachelor of Science diploma in physics should have come with a sticky note appended to it that says, "... yeah, but he pretty much sucked as a physics student."  I struggled in virtually all of my upper-level physics classes, due to a combination of lack of focus and troubles with mathematics that I never figured my way out of.  The result is that I have a degree in physics, but reading an academic paper on the topic loses me after the first couple of paragraphs.

But so much of physics is so incredibly cool that I wish I understood it better.  The paper I took a look at yesterday (it'd be a vast exaggeration to say I "read" it) is a real coup -- if its findings bear out, it stands a good chance of solving two of the most perplexing questions of subatomic physics.

The first is akin to the planetary spacing issue I dealt with here a couple of days ago.  It asks a curious question: why do the fundamental particles have the masses they do?  Photons are massless; neutrinos damn close, but have a very tiny amount of mass; electrons are next (along with their relatives, muons), then protons and neutrons, and on up the scale to very heavy (and short-lived) particles like the "double-charmed xi baryon" which has four times the rest mass of a proton and a half-life so short it hasn't been measured yet, but is probably less than 10 ^-14 seconds (that's a decimal point, followed by thirteen zeros and a one -- better known to us non-physicists as "really, really short").

The other question is one I've looked at here before; the nature of the mysterious "dark matter" that makes up something like a quarter of the known mass of the universe, but thus far has resisted all detection by anything but its mysterious gravitational signature.  We don't know what it's made of, nor how (or if) it interacts with itself or other forms of matter.

I've commented about it that just as the odd constancy of the speed of light in a vacuum regardless of the reference frame of the observer waited around for a genius -- in this case, Einstein -- to explain it, the baffling dark matter is waiting for this century's Einstein to have the requisite insight.

[Image licensed under the Creative Commons Illustris Collaboration, Illustris Dark Matter and Gas, CC BY-SA 4.0]

Well, the waiting may be over.  A trio of physicists at Johannes Gutenberg University Mainz -- Adrian Carmona, Javier Castellano Ruiz, and Matthias Neubert -- have come up with a theoretical framework that, if it bears out, explains both the fundamental particle masses and the nature of dark matter in one fell swoop, by proposing an additional fundamental particle and force that act on matter through a tightly-coiled extra spatial dimension.

A press release at Science Daily describes their research this way:

In a recent paper published in the European Physical Journal C, the researchers found a spectacular resolution to this dilemma.  They discovered that their proposed particle would necessarily mediate a new force between the known elementary particles (our visible universe) and the mysterious dark matter (the dark sector).  Even the abundance of dark matter in the cosmos, as observed in astrophysical experiments, can be explained by their theory.  This offers exciting new ways to search for the constituents of the dark matter -- literally via a detour through the extra dimension -- and obtain clues about the physics at a very early stage in the history of our universe, when the dark matter was produced.

"After years of searching for possible confirmations of our theoretical predictions, we are now confident that the mechanism we have discovered would make the dark matter accessible to forthcoming experiments, because the properties of the new interaction between ordinary matter and dark matter -- which is mediated by our proposed particle -- can be calculated accurately within our theory," said study co-author Matthias Neubert.  "In the end -- so our hope -- the new particle may be discovered first through its interactions with the dark sector."

This, gentle readers, is what is known as "Nobel Prize material."

If, of course, it is confirmed by further research and investigation.  The thing that makes me hopeful is that the theories with the greatest likelihood of success are the ones that explain several problems at once; consider, for example, how the quantum mechanical model simultaneously accounted for the energy levels in hydrogen atoms, the bizarre double-slit experiment, Heisenberg's Uncertainty Principle, and the collapse of the wave function (most famous for being responsible for the Schrödinger's Cat phenomenon).  A really powerful model has enormous breadth, depth, and explanatory power, and this one -- at least from a preliminary look -- seems to have all three.

But, as I pointed out at the beginning, that's from the point of view of a dilettante.  I'm hardly qualified to assess whether the Carmona et al. paper will withstand scrutiny from the experts or will end up as another in the very long list of ideas that didn't pan out.  So keep your eyes on the news.

It might be that we are about to turn the lights on in the dark sector for the first time ever.

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Science fiction enthusiasts will undoubtedly know the classic 1973 novel by Arthur C. Clarke, Rendezvous with Rama.  In this book, Earth astronomers pick up a rapidly approaching object entering the Solar System, and quickly figure out that it's not a natural object but an alien spacecraft.  They put together a team to fly out to meet it as it zooms past -- and it turns out to be like nothing they've ever experienced.

Clarke was a master at creating alien, but completely consistent and believable, worlds, and here he also creates a mystery -- because just as if we really were to find an alien spacecraft, and had only a limited amount of time to study it as it crosses our path, we'd be left with as many questions as answers.  Rendezvous with Rama reads like a documentary -- in the middle of it, you could easily believe that Clarke was recounting a real rendezvous, not telling a story he'd made up.

In an interesting example of life imitating art, in 2017 astronomers at an observatory in Hawaii discovered an object heading our way fast enough that it has to have originated outside of our Solar System.  Called 'Oumuamua -- Hawaiian for "scout" -- it had an uncanny, if probably only superficial, resemblance to Clarke's Rama.  It is long and cylindrical, left no gas or dust plume (as a comet would), and appeared to be solid rather than a collection of rubble.  The weirdest thing to me was that backtracking its trajectory, it seems to have originated near the star Vega in the constellation Lyra -- the home of the superintelligent race that sent us a message in the fantastic movie Contact.

The strangeness of the object led some to speculate that it was the product of an extraterrestrial intelligence -- although in fairness, a team in 2019 gave their considered opinion that it wasn't, mostly because there was no sign of any kind of internal energy source or radio transmission coming from it.  A noted dissenter, though, is Harvard University Avi Loeb, who has laid out his case for 'Oumuamua's alien technological origin in his new book Extraterrestrial: The First Sign of Intelligent Life Beyond Earth.

His credentials are certainly unimpeachable, but his book is sure to create more controversy surrounding this odd visitor to the Solar System.  I won't say he convinced me -- I still tend to side with the 2019 team's conclusions, if for no other reason Carl Sagan's "Extraordinary Claims Require Extraordinary Evidence" rule-of-thumb -- but he makes a fascinating case for the defense.  If you are interested in astronomy, and especially in the question of whether we're alone in the universe, check out Loeb's book -- and let me know what you think.

[Note: if you purchase this book using the image/link below, part of the proceeds go to support Skeptophilia!]

Rushing toward a paradigm shift

I have a sneaking suspicion that the physicists are on the threshold of a paradigm-breaking discovery.

The weird data have been building up for some time now, observations and measurements that are at odds with our current models of how the universe works.  I say "models (plural)" because one of the most persistent roadblocks in physics is the seeming incompatibility of quantum mechanics and general relativity -- in other words, coming up with a Grand Unified Theory that pulls a consistent explanation of gravity into our conceptual framework for the other three fundamental forces (electromagnetism and the weak and strong nuclear forces).  All attempts to come up with an amalgam have either "led to infinities" (had places in the relevant equations that generate infinite answers, usually an indicator that something is seriously wrong with your model) or have become so impossibly convoluted that even the experts can't agree on the details (such as string theory with its eleven spatial dimensions, something that's always reminded me of Ptolemy's flailing about to save the geocentric model by adding more loops and twists and epicycles so the data would fit).

And still the anomalous data keep rolling in.  Three weeks ago I wrote about a troubling discrepancy that's been discovered in the value of the Hubble Constant, which describes the rate of expansion of the universe -- there are two ways to measure it, which presumably should give the same answer, but don't.

Then last week, physicists at a lab in Hungary announced that they'd found new evidence of "X17," a mysterious particle that could be a carrier for a fifth fundamental force.  The argument is a bit like the observation that led to the discovery of the neutrino back in 1959 -- during beta radioactive decay, the particles emitted seemed to break the laws of conservation of energy and momentum, until that time strictly enforced in all jurisdictions.  Wolfgang Pauli said, basically, "Well, that can't be right," and postulated that an undetected particle was carrying off the "lost" momentum and energy.  It took twenty-eight years to prove, but he was right.

Here, it's the behavior another radioactive substance, beryllium-8, which emits light at the "wrong" angle to account for all of the energy involved (again, breaking the law of conservation of energy).  Conservation could be re-established if there was an undetected particle being emitted with a mass of 17 MeV (about 33 times the rest mass of an electron).  Even considering the neutrino, this seemed a little bit ad hoc -- "we need a particle, so we'll invent one to make our data fit" -- until measurements from an excited helium nucleus generated anomalous results that could be explained by a fifth force carried by a particle with exactly the same mass.

Hmm.  Curiouser and curiouser.

If that's not enough, just this week a paper appeared in Nature Astronomy about that elusive and mysterious substance "dark matter" that, despite defying every effort to detect it, outweighs the ordinary matter you and I are made of by a factor of five.  Its gravitational signature is everywhere, and appears to be most of what's responsible for holding galaxies together -- without it, the Milky Way and other rotating galaxies would fly apart.

But what is it?  No one knows.  There are guesses, but once again, those guesses have come up empty-handed with respect to any kind of experimental verification.  (And that's not even considering the even-weirder dark energy, which outweighs dark matter by a factor of two, and is thus the most common stuff in the universe, comprising 68% of what's out there -- even though we have not the slightest clue what it might be.)

The paper, by a team led by astrophysicist Qi Guo of the Chinese Academy of Sciences, is called, "Further Evidence for a Population of Dark-Matter-Deficient Dwarf Galaxies," and describes no less than nineteen different galaxies that have significantly less dark matter than conventional explanations (such as they are) would need to explain (1) how they formed, and (2) what's holding them together.  Lead author Guo, for her part, is baffled, and although the data seem solid, she admits to being at a bit of a loss.  "We are not sure why and how these galaxies form," she said, in a press release in Science News.

Elliptical galaxy Abell S740 [Image is in the Public Domain, courtesy of NASA]

So the anomalous observations keep piling up, and thus far, no one has been able to explain them, much less reconcile them with all the others.  I'm reminded of what Thomas Kuhn wrote, in his seminal book The Structure of Scientific Revolutions: "Scientific revolutions are inaugurated by a growing sense... that an existing paradigm has ceased to function adequately in the exploration of an aspect of nature to which that paradigm itself had previously led the way."

It must be both nerve-wracking and exhilarating to be a physicist right now.  Nerve-wracking because suddenly finding out that your previous model, the one you were taught to understand and cherish during your training, is inadequate -- well, the response is frequently to do what Irish science historian, writer, and filmmaker James Burke calls "scrambling about to stop the rug from being pulled out from under years of happy status-quo."  On the one hand, you can understand that, apart from any emotional attachment one might have to an accepted model; it is an accepted model because it worked perfectly well for a while, accounting for all the evidence we had.  And there are countless examples when a model was challenged by what appeared to be contradictory data, and it turned out the data were mismeasurements, misinterpretations, or outright fabrications.

Which is why Pauli was so sure that the neutrino existed -- the law of conservation of energy, he reasoned, was so well-supported that it just couldn't be wrong.

But now -- well, as I said, that data keep piling up.  Whatever's going on here, they aren't all mismeasurements.  It remains to be seen what revision of our understanding will sweep away all the oddities and internal contradictions and make sense of what the physicists are seeing, but I have no doubt we'll find it at some point.

And there's the exhilarating part of it.  What a time to be in research physics -- when the race is on to pull together and explain an increasingly huge body of anomalous stuff, and revise our understanding of the universe in a fundamental way.  It's the kind of climate in which Nobel Prizes are won.

Being an observer is exciting enough; I can't imagine what it might be like to be inside it all.

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Long-time readers of Skeptophilia have probably read enough of my rants about creationism and the other flavors of evolution-denial that they're sick unto death of the subject, but if you're up for one more excursion into this, I have a book that is a must-read.

British evolutionary biologist Richard Dawkins has made a name for himself both as an outspoken atheist and as a champion for the evolutionary model, and it is in this latter capacity that he wrote the brilliant The Greatest Show on Earth.  Here, he presents the evidence for evolution in lucid prose easily accessible to the layperson, and one by one demolishes the "arguments" (if you can dignify them by that name) that you find in places like the infamous Answers in Genesis.

If you're someone who wants more ammunition for your own defense of the topic, or you want to find out why the scientists believe all that stuff about natural selection, or you're a creationist yourself and (to your credit) want to find out what the other side is saying, this book is about the best introduction to the logic of the evolutionary model I've ever read.  My focus in biology was evolution and population genetics, so you'd think all this stuff would be old hat to me, but I found something new to savor on virtually every page.  I cannot recommend this book highly enough!

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]