Tense situation

In my Critical Thinking classes, I did a unit on statistics and data, and how you tell if a measurement is worth paying attention to.  One of the first things to consider, I told them, is whether a particular piece of data is accurate or merely precise -- two words that in common parlance are used interchangeably.

In science, though, they don't mean the same thing.  A piece of equipment is said to be precise if it gives you close to the same value every time.  Accuracy is a higher standard; data are accurate if the values are not only close to each other when measured with the same equipment, but agree with data taken independently, using a different device or a different method.

A simple example is that if my bathroom scale tells me every day for a month that my mass is (to within one kilogram either way) 239 kilograms, it's highly precise, but very inaccurate.

This is why scientists always look for independent corroboration of their data.  It's not enough to keep getting the same numbers over and over; you've got to be certain those numbers actually reflect reality.

This all comes up because of an exciting new approach to one of the most vexing scientific questions known -- the rate of expansion of the entire universe.

[Image is in the Public Domain, courtesy of NASA]

A while back, I wrote about some experiments that were allowing physicists to home in on the Hubble constant, a quantity that is a measure of how fast everything in the universe is flying apart.  And initially, the news appeared to be good; from a range of between 50 and 500, physicists had been able to narrow down the value of the Hubble constant to between 65.3 and 75.6.

The problem is, nobody's been able to get closer than that -- and in fact, recent measurements have widened, not narrowed, the gap.

There are two main ways to measure the Hubble constant.  The first is to use information from Type 1A supernovae (whose brightening and eventual dimming curves are connected to their intrinsic brightness) and Cepheid variables (stars whose period of brightness oscillation varies predictably with their luminosity); these properties make them good "standard candles" to determine the distance to other galaxies.  Once you know a star's intrinsic luminosity, you can use that to determine how far away it is -- just as you can estimate your distance to an oncoming motorcycle at night because you know how bright a motorcycle's headlight actually is.  This, coupled with the galaxy's redshift, allows you to figure out how fast the galaxies we see are receding from each other, and thus, how fast space is expanding. 

The other method is to use the cosmic microwave background radiation -- the leftovers from the radiation produced by the Big Bang -- to determine the age of the universe, and therefore, how much bigger it's gotten since then.  The problem with this method is that it relies heavily on the correctness of our current models of the evolution of the universe, some of which have resulted in predictions not matched by the available observations.

Here's the issue: not only does each of the methods -- standard candles/cosmic ladder, and the CMBR method -- each have its difficulties, the measurement of the Hubble constant by these two methods has resulted in two irreconcilably different values.

So the astrophysicists have tried to narrow in from both ends.  Improve the data, and improve the models.  This backfired.  As our measurement ability has become more and more precise, the error bars associated with data collection have shrunk considerably; at the same time, the models have improved dramatically.  You'd think this would result in the two values getting closer and closer together.

Exactly the opposite has happened.

This result, called the Hubble tension, is considered to be one of the most frustrating problems in astrophysics.  And it's not just some fringe-y side quest; this is a fundamental issue with our understanding of the entire universe.

Here's where the new research, out of the Technical University of Münich, comes in.  You probably know about the phenomenon of gravitational lensing, where light traveling through the curved space near a massive object (like a galaxy or a supermassive black hole) gets bent, in much the same fashion as light going through a glass lens.  Sometimes this causes distant bright objects to look like they're stretched, or even multiplied.  For these objects, there is more than one pathway the light can take through space to get here to us, so the image we see is distorted.

Well, we've just detected one of the most remarkable examples of gravitational lensing ever observed; a supernova in a brilliant galaxy whose light split up into five separate paths in order to get here.

Put a different way, we saw the same supernova occur five different times.

Now, here's the kicker: because the paths that each of those beams of light took to get here differ in distance, comparing the timing of arrival of each image could give us the first-ever direct, no-assumptions-required method of measuring the Hubble constant, one with far fewer systematic uncertainties.

"We nicknamed this supernova SN Winny, inspired by its official designation SN 2025wny," said astrophysicist Sherry Suyu, who co-wrote the paper on the discovery.  "It is an extremely rare event that could play a key role in improving our understanding of the cosmos.  The chance of finding a superluminous supernova perfectly aligned with a suitable gravitational lens is lower than one in a million.  We spent six years searching for such an event by compiling a list of promising gravitational lenses, and in August 2025, SN Winny matched exactly with one of them."

In-depth analysis of the timing and positions of the five supernova appearances is currently underway.

Whether this will resolve the Hubble tension, of course, remains to be seen.  The worst-case scenario is that the SN Winny data doesn't agree with either the cosmic ladder value or the CMBR value, or has error bars large enough to overlap with both.  A happier outcome would be a decisive landing in one camp or the other -- although that'd still leave the astrophysicists puzzling over why the losing method doesn't work.

But it's an incredible discovery, and I know I'll be watching the science news to see what comes out of it.  Settling the Hubble tension question would be an amazing coup; having it resolved because of a one-in-a-million observation of a lensed supernova -- well, if you don't find that super cool, I don't even know what to say to you.

****************************************

Opinions, experts, and ignorance

I may have many faults, but one thing I try my damnedest not to do is to spout off on topics about which I am clearly ignorant.

That determination to limit my own pontificating to subjects upon which I have earned some right to pontificate is, unfortunately, not shared by a lot of people.  How many times have you heard someone say, "Well, I'm no expert, but...", followed by some ridiculous claim that appears to have been pulled directly from the person's nether orifice?

Well, if you're no expert, maybe a good strategy would be to keep your damn mouth shut.  Or, better still, to learn something about the topic at hand before you try to make a cogent statement about it.  If I know nothing about a subject, my opinions about it are very nearly worthless -- and personally, I don't have any need to pretend they aren't.

Sadly, "I have a right to my own opinion" seems, for a lot of people, to trump everything and everyone else, including people who have spent their entire lives studying the subject.

Which, unsurprisingly, brings us to Joe Rogan.

Rogan has turned this kind of thing into performance art.  He went to the University of Massachusetts for a while, but dropped out because he thought it was "pointless."  His two main accomplishments since then are fighting for (and later being a commentator for) the UFC, and being a stand-up comedian and podcaster.  His show The Joe Rogan Experience is one long litany of pride-in-ignorance.  He's an on-again, off-again antivaxxer, and was one of the principal distributors of misinformation during the first months of the COVID-19 epidemic.  He hates former Canadian Prime Minister Justin Trudeau with a passion, calling him "a fucking dictator" -- but in the next breath admitted he has "zero understanding of Canada's political system."  He called Israel's actions in Gaza "genocide," but ten days later had policy specialist Coleman Hughes as a guest, and when Hughes took Rogan to task about his assessment, Rogan shrugged it off with, "well, you know a lot more about it than I do."

Well, if you have "zero understanding" of something, maybe you shouldn't be talking about it on your radio show, mmmm?  As Neil deGrasse Tyson put it, "If you don't know, then that's where the conversation should stop."

The reason Rogan's name comes up is because (ignorance notwithstanding) he is still way near the front of the pack in media popularity, despite two instances just in the last couple of weeks demonstrating that he apparently spends his spare time doing sit-ups underneath parked cars.

In the first, he went on a long, rambling diatribe about how the 1969 Moon landing was definitely faked.  Probably by director Stanley Kubrick, of 2001: A Space Odyssey fame, because "That guy could fake it one hundred percent."

"People keep secrets," Rogan said.  "This idea that people can’t keep secrets because some people can’t keep secrets—high level military guys keep secrets all the fucking time.  They go to the grave with those secrets."

Oh, and there's no way astronauts could pass through the Van Allen radiation belts alive, he says.  "They never even flew a chicken through those fucking things and had it come back alive."

Well, at least he's right about that much.  NASA has sent exactly zero chickens into space.

So righty-o.  Back to reality.  We've known about the Van Allen belts since 1958, and sent probes up there repeatedly to measure radiation flux, and the astronomers (i.e. the people who actually know what the hell they're talking about) found that with proper shielding, both delicate technology and human beings could safely pass through them.  Me, I'm inclined to trust that over the rantings of a kickboxer-turned-podcaster.

But in the words of the infomercial, "Wait, there's more!"  Rogan also weighed in on cosmology last week -- because of course he did -- and said that in his opinion, Jesus makes more sense than the Big Bang:

People would be incredulous about the resurrection of Jesus Christ, but yet they’re convinced that the entire universe was smaller than the head of a pin.  And for no reason than anybody’s adequately explained to me, that makes sense… instantaneously became everything.  Yeah.  Okay. I can’t buy that.  I’m sticking with Jesus on that one.  Like, Jesus makes more sense.

Now, I'm not going to get into the resurrection of Jesus -- Cf. my earlier comment about my not broadcasting my opinion in domains where I am manifestly unqualified -- but I do know a bit about cosmology, and what is clear from Rogan's statement is that he is apparently incapable even of comprehending the damn Wikipedia page on the Big Bang, wherein he (or anyone else) could have the topic "adequately explained" to them in five minutes or so.  

Or maybe he just can't be bothered.

Or both.

[Image licensed under the Creative Commons Attribution 3.0 Unported license, Steven Crowder, February 2017]

But to return to my earlier point; why does anyone think this man's opinions, on topics where he himself demonstrates (and occasionally admits) complete ignorance, have any relevance?  If I were completely ignorant of geology, I might have the "opinion" that the interior of the Earth was filled with vanilla butter frosting with sprinkles, but that wouldn't affect the science at all -- it would just demonstrate that I was in no position to have my views taken seriously.

So why, why do people still listen to this guy?  Is it because his routine is mildly entertaining?  Is it because he might eventually say something correct, and the listeners are breathlessly waiting for that moment?

Or is it, heaven forfend, that people actually believe him?

I dunno.  It's probably not worth fighting someone who does what he does in the name of "entertainment."  But the news in the last few days has been pretty dismal, and this just kinda pushed me over the edge.

I so want to get back to a world where we trust experts.  Not blindly; experts can be mistaken just like anyone else (in fact, a recent discovery in physics seems to have invalidated some earlier research -- for which the researchers had won the Nobel Prize).  But the fact is that people who are trained in science, and spent their entire lives studying the field, are far less likely to be mistaken within their area of study than us laypersons.  Not only do they know the facts and understand the models, they get how evidence and data work -- and when a particular claim is supported and when it is not.  The current "don't trust the experts" thing, promulgated by loudmouths all the way up to and including Donald Trump, is deeply mystifying to me.

Anyhow, this is likely to earn me hate mail from people who love Joe Rogan.  I'm okay with that.  If you think everything he says makes sense, or that his claims should somehow be on the same plane as actual scientists, you and I don't have much common ground anyhow.  

****************************************

Bounce

Today's post is about a pair of new scientific papers that have the potential to shake up the world of cosmology in a big way, but first, some background.

I'm sure you've all heard of dark energy, the mysterious energy that permeates the entire universe and acts as a repulsive force, propelling everything (including space itself) outward.  The most astonishing thing is that it appears to account for 68% of the matter/energy content of the universe.  (The equally mysterious, but entirely different, dark matter makes up another 27%, and all of the ordinary matter and energy -- the stuff we see and interact with on a daily basis -- only comprises 5%.)

Dark energy was proposed as an explanation for why the expansion of the universe appears to be speeding up.  Back when I took astronomy in college, I remember the professor explaining that the ultimate fate of the universe depended only on one thing -- the total amount of mass it contains.  Over a certain threshold, and its combined gravitational pull would be enough to compress it back into a "Big Crunch;" under that threshold, and it would continue to expand forever, albeit at a continuously slowing rate.  So it was a huge surprise when it was found out that (1) the universe's total mass seemed to be right around the balance point between those two scenarios, and yet (2) the expansion was dramatically speeding up.

So the cosmological constant -- the "fudge factor" Einstein threw in to his equations to generate a static universe, and which he later discarded -- seemed to be real, and positive.  In order to explain this, the cosmologists fell back on what amounts to a placeholder; "dark energy" ("dark" because it doesn't interact with ordinary matter at all, it just makes the space containing it expand).  So dark energy, they said, generates what appears to be a repulsive force.  Further, since the model seems to indicate that the quantity of dark energy is invariant -- however big space gets, there's the same amount of dark energy per cubic meter -- its relative effects (as compared to gravity and electromagnetism, for example) increase over time as the rest of matter and energy thins.  This resulted in the rather nightmarish scenario of our universe eventually ending when the repulsion from dark energy overwhelms every other force, ripping first chunks of matter apart, then molecules, then the atoms themselves.

The "Big Rip."

[Image is in the Public Domain courtesy of NASA]

I've always thought this sounded like a horrible fate, not that I'll be around to witness it.  This is not even a choice between T. S. Eliot's "bang" or "whimper;" it's like some third option that's the cosmological version of being run through a wood chipper.  But as I've observed before, the universe is under no compulsion to be so arranged as to make me happy, so I reluctantly accepted it.

Earlier this year, though, there was a bit of a shocker that may have given us some glimmer of hope that we're not headed to a "Big Rip."  DESI (the Dark Energy Spectroscopic Instrument) found evidence, which was later confirmed by two other observatories, that dark energy appears to be decreasing over time.  And now a pair of papers has come out showing that the decreasing strength of dark energy is consistent with a negative cosmological constant, and that value is exactly what's needed to make it jibe with a seemingly unrelated (and controversial) model from physics -- string theory.

(If you, like me, get lost in the first paragraph of an academic paper on physics, you'll get at least the gist of what's going on here from Sabine Hossenfelder's YouTube video on the topic.  If from there you want to jump to the papers themselves, have fun with that.)

The upshot is that dark energy might not be a cosmological constant at all; if it's changing, it's actually a field, and therefore associated with a particle.  And the particle that seems to align best with the data as we currently understand them is the axion, an ultra-light particle that is also a leading candidate for explaining dark matter!

So if these new papers are right -- and that's yet to be proven -- we may have a threefer going on here.  Weakening dark energy means that the cosmological constant isn't constant, and is actually negative, which bolsters string theory; and it suggests that axions are real, which may account for dark matter.

In science, the best ideas are always like this -- they bring together and explain lots of disparate pieces of evidence at the same time, often linking concepts no one even thought were related.  When Hess, Matthews, and Vine dreamed up plate tectonics in the 1960s, it explained not only why the continents seemed to fit together like puzzle pieces, but the presence and age of the Mid-Atlantic Ridge, the magnetometry readings on either side of it, the weird correspondences in the fossil record, and the configuration of the "Pacific Ring of Fire" (just to name a few).  Here, we have something that might simultaneously account for some of the biggest mysteries in cosmology and astrophysics.

A powerful claim, and like I said, yet to be conclusively supported.  But it does have that "wow, that explains a lot" characteristic that some of the boldest strokes of scientific genius have had.

And, as an added benefit, it seems to point to the effects of dark energy eventually going away entirely, meaning that the universe might well reverse course at some point and then collapse -- and, perhaps, bounce back in another Big Bang.  The cyclic universe idea, first described by the brilliant physicist Roger Penrose.  Which I find to be a much more congenial way for things to end.

So keep your eyes out for more on this topic.  Cosmologists will be working hard to find evidence to support this new contention -- and, of course, evidence that might discredit it.  It may be that it'll come to nothing.  But me?  I'm cheering for the bounce.

A fresh start might be just what this universe needs.

****************************************

Miracles and incredulity

I have a problem with how people use the word miracle.

The dictionary definition is "a surprising and welcome event that is not explicable by natural or scientific laws and is therefore considered to be the work of a divine agency."  So this would undoubtedly qualify:

The Miracle of St. Mark, by Jacopo Tintoretto (ca. 1548) [Image is in the Public Domain]

But other than claims of honest-to-goodness angels appearing and stopping someone from getting murdered, the occurrences people usually call miracles seem to fall into two categories:

1. Events that have a positive outcome where one can imagine all sorts of ways they could have gone very wrong.  An example is when I was driving down my road in the middle of winter, hit a patch of black ice, and spun out -- coming to rest in a five-meter-by-five-meter gravel patch without hitting anything, where other trajectories would have taken me into a creek, an embankment, or oncoming traffic.
2. Events that are big and impressive, and about which we don't understand the exact cause.

It's the second category that attracted the attention of one Michael Grosso, who writes over at the site Consciousness Unbound, in a post this week called "A Trio of Obvious Miracles."  I was intrigued to find out what Grosso thought qualified not only as miracles but as obvious ones, and I was a little let down to find out that they were (1) the Big Bang, (2) the appearance of life, and (3) the evolution of consciousness.

The problem with all three of these is a lack of information.  In the first case, we have a pretty good idea what happened shortly after the Big Bang -- and by "shortly after" I mean "more than 10^-35 seconds after" -- but no real idea what triggered the expansion itself, or what came before it.  (If "before the Big Bang" even has any meaning.  Stephen Hawking said the question was like asking "what is north of the North Pole?"  Roger Penrose, on the other hand, thinks that a cyclic universe is a real possibility, and there may be a way to detect the traces of iterations of previous universes left behind in our current one.  The question is, at present, still being hotly debated by cosmologists.)

As far as Grosso's second example -- the origins of life -- that's more in my wheelhouse.  The difficulty here is that even the biologists can't agree about what makes something "alive."  Freshman biology texts usually have a list of characteristics of life, which include:

• made of one or more cells
• shows high levels of organization
• capable of reproduction
• capable of growth
• has a limited life span
• responds to stimuli
• adapts through natural selection
• has some form of a genetic code
• has a metabolism/use of energy

Not only are there organisms that are clearly alive but break one or more rules (sterile hybrids are incapable of reproducing, bristlecone pines appear to have no upper bound on their life spans), there are others, such as viruses, that have a few of the characteristics (organization, reproduction, limited life span, adaptation, and genetic code) while lacking others (cells, growth, response, and independent metabolism).  We talk about something "killing viruses," but the jury's still out as to whether they were alive in the first place.  (Perhaps "inactivating" them would be more accurate.)  In any case, the search for some ineffable something that differentiates life from non-life, like Henri Bergson's élan vital, have been unsuccessful.

With the final example, consciousness, we're on even shakier ground.  Once again starting with the dictionary definition -- "an awareness of one's internal and/or external environment, allowing for introspection, imagination, and volition" -- it remains to be seen whether we're unique in having consciousness, or if it (like intelligence) exists on a spectrum.  I'd argue that my dogs are conscious, but are insects?  How about earthworms?  How about amoebas?  All of them have some awareness of their external world, as evidenced by their moving toward pleasant stimuli and away from unpleasant ones; but I doubt very much if amoebas think about it.  So is our much more complex experience of consciousness simply due to our large and highly-interconnected brains, which would suggest that consciousness arises from a purely physical substratum?  If so, would it be possible to emulate it in a machine?  Some people are arguing, from a Turing-esque "if you can't tell the difference, there is no difference" stance, that large language models such as ChatGPT are already showing signs of consciousness.  While I find that a little doubtful -- although admittedly, I'm no expert on the topic -- it seems like we're in the same boat with consciousness as we are with life; it's hard to argue about something when we can't even agree on what the definition is, especially when the characteristic in question seems not to exist on a binary, you've-got-it-or-you-don't basis.

In any case, the whole thing seems to boil down to an argument from incredulity -- "I can't explain this, so it must be a miracle."  Grosso writes:

I grant the astonishing character of the miraculous, and the rarity.  But in the parapsychological definition, the term refers to phenomena that are extraphysical; cannot be physically explained. But what is causing these deviations from physical reality?...  Of course, we generally don’t kneel in awe at the miraculous sunrise or shudder with wonder as we wolf a burger down our gullet.  We are in fact swamped by what in fact are obvious miracles, the whole of nature and life in its wild multiplicity.  But thanks to habit and routine our imagination of the marvelous is deadened.

Honestly, I'm not even all that convinced about the rarity of miracles.  He's picked three things that -- so far as we know -- only happened once, and from that deduced that they're miraculous.  I did a post here a couple of years ago about Littlewood's Law of Miracles (named after British mathematician John Edensor Littlewood), which uses some admittedly rather silly mathematical logic to demonstrate that we should, on average, expect a miracle to occur every other month or so.  So I'm not sure that our perception of something as unlikely (and therefore miraculous) means much. 

The thing is, we can't really deduce anything from a lack of information.  Myself, I'm more comfortable relying on science to elucidate what's going on; like the astronomer Pierre-Simon Laplace famously said to Napoleon when the latter asked why Laplace's book on celestial mechanics made no mention of God, "Je n'avais pas besoin de cette hypothèse-là" ("I have no need of that hypothesis.").  If you're claiming something is a miracle, you're saying it's outside the capacity of science to explain, and that seems to me to be very premature.

My stance is that in all three cases he cited, science hasn't explained them yet.  And that little word at the end is doing a lot of heavy lifting.

****************************************

The cracked mirror

Why is there something rather than nothing?

It's the Mother of All Existential Questions, and has been batted around for as long as there've been philosophers there to ask it.  Some attribute the universe's something-ness to God, or some other uncreated Creator; predictably, this doesn't satisfy everyone, and others have looked for a more scientific explanation of why a universe filled with stuff somehow took precedence over one that was completely empty.

Probably the most thought-provoking scientific answer to the "something versus nothing" debate I came across in Jim Holt's intriguing book Why Does the World Exist?, in which he interviews dozens of scientists, philosophers, and deep thinkers about how they explain the plenitude of our own universe.  You've probably run across the Heisenberg Uncertainty Principle -- the bizarre, but extensively tested, rule that in the quantum realm there are pairs of measurable quantities called canonically conjugate variables that cannot be measured to a high degree of precision at the same time.  The best-known pair of canonically conjugate variables is position and momentum; the more accurately you know a particle's position, the less you can even theoretically know about its momentum, and vice-versa.  And this is not just a problem with our measuring devices -- that balance between exactitude and fuzziness is built into the fabric of the universe.

A less widely-known pair that exists in the same relationship is energy and time duration.  If you know the energy content of a region of space to an extremely high degree of accuracy, the time during which that energy measurement can apply is correspondingly extremely short.

The question Holt asks is: what would happen if you had a universe with nothing in it -- no matter, no energy, no fields, nothing?

Well, that would mean that you know its energy content exactly (zero), and the time duration over which that zero-energy state applies (infinitely long).  And according to Heisenberg, those two things can't be true at the same time.

The upshot: nothingness is unstable.  It's like a ball balanced at the top of a steep hill; a tiny nudge is all it takes to change its state.  If there had been a moment when the universe was completely Without Form And Void (to borrow a phrase), the Uncertainty Principle predicts that the emptiness would very quickly decay into a more stable state -- i.e., one filled with stuff.

There's another layer to this question, however, which has to do not with why there's something rather than nothing, but why the "something" includes matter at all.  I'm sure you know that for every subatomic particle, there is an antimatter version; one whose properties such as charge and spin are equal and opposite.  And every Star Trek fan knows that if matter and antimatter come into contact with each other, they mutually annihilate, with all of that mass turned into energy according to Einstein's famous mass/energy equation.

[Image licensed under the Creative Commons Dirk Hünniger, Joel Holdsworth, ElectronPositronAnnihilation, CC BY-SA 3.0]

[Nota bene: don't be thrown off by the fact that the arrows on the electrons and positrons appear to indicate one is moving toward, and the other away from, their collision point.  On a Feynman diagram -- of which the above is an example -- the horizontal axis is time, not position.  Matter and antimatter have all of their properties reversed, including motion through time; an electron moving forward through time is equivalent to a positron moving backward through time.  Thus the seemingly odd orientation of the arrows.]

More relevant to our discussion, note in the above diagram, the photon produced by the electron/positron pair annihilation (the wavy line labeled γ) is also capable of producing another electron/positron pair; the reaction works both ways.  Matter and antimatter can collide and produce energy; the photons' energy can be converted back to matter and antimatter.

But here's where it gets interesting.  Because of charge and spin conservation, the matter and antimatter should always be produced in exactly equal amounts.  So if the universe did begin with an unstable state of nothingness decaying into a rapidly-expanding cloud of matter, antimatter, and energy, why hasn't all of the matter and antimatter mutually annihilated by now?

Why isn't the universe -- if not nothing, simply space filled only with photons?

One possible answer was that perhaps some of what we see when we look out into space is antimatter; that there are antimatter worlds and galaxies.  Since antimatter's chemical properties are identical to matter's, we wouldn't be able to tell if a star was made of antimatter by its spectroscopic signature.  The only way to tell would be to go there, at which point you and your spaceship (and a corresponding chunk of the antimatter planet) would explode in a burst of gamma rays, which would be a hell of a way to confirm a discovery.

But there's a pretty good argument that everything we see is matter, not antimatter.  Suppose some galaxy was made entirely of antimatter.  Well, between that galaxy and the next (matter) galaxy would be a region where the antimatter and matter blown away from their respective sources would come into contact.  We'd see what amounts to a glowing wall between the two, where the mutual annihilation of the material would release gamma rays and x rays.  This has never been observed; the inference is that all of the astronomical objects we're seeing are made of ordinary matter.

I'm pretty sure the two would not connected by a weird, foggy celestial bridge, either.

So at the creation of the universe, there must have been a slight excess of matter particles produced, so when all the mutual annihilation was done, some matter was left over.  That leftover matter is everything we see around us.  But why?  None of the current models suggest a reason why there should have been an imbalance, even a small one.

Well -- just possibly -- until now.  A press release from CERN a couple of weeks ago found that there is an asymmetry between matter and antimatter, something called a charge-parity violation, that indicates our previous understanding that matter and antimatter are perfect reversals might have to be revised.  And it's possible this slight crack in the mirror might explain why just after the Big Bang, matter prevailed over antimatter.

“The more systems in which we observe CP violations and the more precise the measurements are, the more opportunities we have to test the Standard Model and to look for physics beyond it,” said Vincenzo Vagnoni, spokesperson for the Large Hadron Collider.  “The first ever observation of CP violation in a baryon decay paves the way for further theoretical and experimental investigations of the nature of CP violation, potentially offering new constraints for physics beyond the Standard Model.”

So that's our mind-blowing excursion into the quantum realm for today. A slight asymmetry in the world of the extremely small that may have far-reaching consequences for everything there is.  And -- perhaps -- explain the deepest question of them all; why the universe as we see it exists.

****************************************

The man who listened to the sky

Arno Allan Penzias was born on the 26th of April, 1933, in Munich, Germany.  It was a fractious time for Germany, and downright dangerous for anyone of Jewish descent, which Penzias was; his grandparents had come from Poland and were prominent members of the Reichenbachstrasse Synagogue.  Fortunately for the family, his parents saw which way the wind was blowing and evacuated Arno and his brother Gunther to Britain as part of the Kindertransport Rescue Operation.  Their father and mother, Karl and Justine (Eisenreich) Penzias, were also able to get out before the borders closed, eventually making their way (as so many Jewish refugees did) to New York City, where they settled in the Garment District.

The younger Penzias had shown a fascination and aptitude for science at a young age, so his choice of a major was never really in doubt.  He went to City College of New York, graduating with a degree in physics in 1954 and ranking near the top of his class.  For a time after graduating he worked as a radar officer in the U. S. Army Signal Corps, but the pull of research drew him back into academia.  In 1962, he earned a Ph.D. in microwave physics from Columbia University, studying with the inventor of the maser, Charles Townes.

Penzias then got a job with Bell Labs in Holmdel, New Jersey, where he worked on developing receivers for the (then) brand-new field of microwave astronomy.  He teamed up with Robert Wilson, an American astronomer, to develop a six-meter-diameter horn reflector antenna with a seven-centimeter ultra-noise receiver, at that point by far the most sensitive microwave detector in the world.

And while using that antenna in 1964, he and Wilson discovered something extremely odd.

At a wavelength of 7.35 centimeters, corresponding to a temperature of around three degrees Kelvin, there was a strong microwave signal -- coming from everywhere.  It seemed to be absolutely uniform in intensity, and was present in the input no matter which direction they aimed the antenna.  It was so perplexing that Penzias and Wilson thought it was an artifact of some purely terrestrial cause -- at first, they thought it might be from pigeon poo on the antenna.  Even after ruling out whatever they could think of (and cleaning up after the pigeons), the signal was still there, a monotonous hiss coming from every spot in the sky.

Before publishing their findings, they started looking for possible explanations, and they found a profound one.  Almost twenty years earlier, physicists Ralph Alpher, Robert Herman, and Robert Dicke had predicted the presence of cosmic microwave background radiation, the relic left behind by the Big Bang.  If the Big Bang model was correct, the unimaginably intense electromagnetic radiation generated by the beginning of the universe would have, in the 13.8-odd billion years since, been "stretched out" by the expansion of the fabric of spacetime, increasing its wavelength and dropping into the microwave region of the spectrum.  Alpher, Herman, and Dicke had predicted that the relic radiation should be under twenty centimeters in wavelength, and should be isotropic -- coming from everywhere in space at a uniform intensity.

That's just what Penzias and Wilson had observed.

In July of 1965, they published their results in the Astrophysical Journal, and suddenly Penzias and Wilson found themselves famous.

Penzias and Wilson at the Holmdel Horn Antenna in June of 1962 [Image is in the Public Domain courtesy of NASA]

At the time, there were two competing theories in cosmology -- the Big Bang model and the Steady-State model.  The latter theorized that the universe was expanding (that much had been undeniable since the discovery of red shift and Hubble's Law) but that as space expanded, matter was continuously being created, so the universe had no fixed start point.  Steady-State was championed by some big names in cosmological research -- Hermann Bondi, Thomas Gold, and Fred Hoyle amongst them -- and trying to figure out a way to discern which was correct had become something of a battle royale in astronomical circles.

But now Penzias and Wilson had made an accidental discovery, coupled it with a pair of (at the time) obscure papers making predictions about the temperature and wavelength of background radiation, and in one fell swoop blew the Steady-State model out of the water.

In 1978 Penzias and Wilson were awarded the Nobel Prize for research that changed the way we see the universe.

Since then, the cosmic microwave background radiation has been studied in phenomenal detail, and we've learned a great deal more about it -- starting with the fact that it isn't perfectly isotropic.  There are tiny but significant irregularities in the temperature of the radiation, something that has yet to be fully explained.  But the majority of the implications of the discovery have stood firm for nearly seventy years; 13.8 billion years ago, spacetime started to expand, and everything we see around us -- all the matter and energy in the universe -- condensed out of that colossally powerful event.  And coming from everywhere in the sky, like a ghostly afterimage of an explosion, is the radiation left behind, stretched out so much that it is outside of the range of human vision, and can only be detected by a telescope tuned to the microwave region of the spectrum.

On Monday, the 22nd of January, 2024, Arno Penzias died at the venerable age of ninety.  The world has lost a brilliant and innovative thinker whose contributions to science are so profound they're hard even to estimate.  The boy who escaped Nazi Germany with his family in the nick of time grew up to be a man who listened to the sky, and in doing so forever altered our understanding of how the universe began.

****************************************

The greatest wall

Sometimes simple words can be the hardest to define accurately.

For example, in physics, what do we mean by the word structure?  The easiest way to conceptualize it is that it's a material object for which whatever force is holding it together outcompetes any other forces that might be involved.  For example, a brick could be considered a structure, because the chemical bonds in the fired clay are stronger than the forces trying to pull it apart.  The sand on a beach, however, doesn't form a single structure, because the forces between the sand grains aren't strong enough to hold them together against the power of the wind and water.

Simple enough, it'd seem, but once you get out into space, it gets a little more difficult.

In astronomy, a structure is something that is bound together by gravity so that on some scale, it acts as a single unit.  The Solar System is a cosmic structure; within it, the gravitational pull of the Sun overwhelms all other forces.  The Milky Way is a cosmic structure by the same definition.  But how big can you get and still call it a single structure?  The question gives astronomers fits, because (to abide by the definition) you have to show that the pieces of the structure are bound together in such a way that the mutual gravitational attraction is higher than the other forces they experience -- and given that a lot of these things are very far away, any such determination is bound to rest on some fairly thin ice.

The largest generally accepted cosmic structure is the Hercules-Corona Borealis Great Wall, a galactic filament that (from our perspective) is in the night sky in the Northern Hemisphere in spring and early summer.  It's ten billion light years in length -- making it a little over a tenth as long as the entire observable universe!

[Image licensed under the Creative Commons Pablo Carlos Budassi, Hercules-CoronaBorealisGreatWall, CC BY-SA 4.0]

In the above image, each one of the tiny dots of light is an entire galaxy containing billions of stars; the brighter blobs are galaxy clusters, each made up of millions of galaxies.

And the whole thing is bound together by gravity.

What's kind of overwhelming about this is that because there are these enormous cosmic structures, there are also gaps between them, called supervoids.  One of the largest is the Boötes Void.  This thing is 330 million light years across, and contains almost no matter at all; any given cubic meter of space inside the void might have a couple of hydrogen atoms, and that's about it.  To put it in perspective; if the Earth was sitting in the center of the Boötes Void, there wouldn't be a single star visible.  It wouldn't have been until the 1960s that we'd have had telescopes powerful enough to detect the nearest stars.

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

What's coolest about all this is where these structures (and the spaces between them) came from.  On the order of 10^-32 seconds (that's 0.00000000000000000000000000000001 seconds) after the Big Bang, the bizarre phenomenon of cosmic inflation had not only blown the universe up by an amount that beggars belief (estimates are that in that first fraction of a second, it expanded from the size of a proton to about the size of a galaxy), it also smoothed out any lumpy bits (what the cosmologists call anisotropies).  This is why the universe today is pretty smooth and homogeneous -- if you look out into space, you see on average the same number of galaxies no matter which way you look.

But there are some pretty damn big anisotropies, like the Hercules-Corona Borealis Great Wall and the Boötes Void.  So where did those come from?

The current model is that as inflation ended, an interaction between regular matter and dark matter triggered a shock wave through the plasma blob that at that point was the entire universe.  This shock wave -- a ripple, a pressure wave much like a sound wave propagating through the air -- pushed some bits of the regular matter closer together and pulled some bits apart, turning what had been a homogeneous plasma into a web of filaments, sheets... and voids.

These baryon acoustic oscillations, that occurred so soon after the Big Bang it's hard to even wrap my brain around a number that small, are why we now have cosmic structures millions, or billions, of light years across.

So that's our mindblowing science for today.  Gravitationally-linked structures that span one-tenth of the size of the observable universe, and spaces in between containing damn near nothing at all, all because of a ripple that passed through the universe when it was way under one second old.

If that doesn't make you realize that all of our trials and tribulations here on Earth are insignificant, nothing will.

****************************************

Here are the answers to the puzzles from yesterday's post.  If you haven't finished thinking about them on your own, scroll no further!

1.  The census taker puzzle

The first clue is that the product of the daughters' ages is equal to 36.  There are eight possible trios of numbers that multiply to 36: (1, 1, 36), (1, 2, 18), (1, 3, 12), (1, 4, 9), (1, 6, 6), (2, 2, 9), (2, 3, 6), and (3, 3, 4).  Clue #2 is that the ages sum to equal the house number across the street, so the next step is to figure out what the house number could be.  Respectively: 38, 21, 16, 14, 13, 13, 11, and 10.

The key here is that when the census taker looks at the house number across the street, he still can't figure it out.  So it can't be (1, 4, 9), for example -- because if it was, as soon as he saw that the house number was 14, he'd know that was the only possible answer.  The fact that even after seeing the house number, he still doesn't know the answer, means it has to be one of the two trios of numbers that sums to the same thing -- 13.  So it either has to be (1, 6, 6) or (2, 2, 9).

Then, clue #3 is that the man's oldest daughter has red hair.  In the first possibility, there is no oldest daughter -- the oldest children are twins.  So his daughters have to be a nine-year-old and a pair of two-year-old twins.

2.  The St. Ives riddle

The answer is one.  "As I was going to St. Ives..." -- it doesn't say a thing about where the other people he met were going, if anywhere.

3.  The bear

It's a white bear.  The only place on Earth you could walk a mile south, a mile east, and a mile north and end up back where you started is if your starting place was the North Pole.

4.  A curious sequence

The pattern is that it's the names of the single digit numbers in English, in alphabetical order.  So the next one in the sequence is 3.

5.  Classifying the letters

The letters are classified by their symmetry.  (The capital letters only, of course.)  Group 1 is symmetrical around a vertical line, Group 2 around a horizontal line, Group 3 is around either a horizontal or a vertical line, Group 4 has no line symmetry but is symmetrical through a 180-degree rotation around their central point, and Group 5 are asymmetrical.

6.  The light bulb puzzle

Turn on switch one, and leave it on.  Turn on switch two for ten minutes, then turn it off.  Leave switch three off.  Go up to the tenth floor.  The bulb operated by switch one will be on; the one operated by switch two will be dark, but hot; and the one operated by switch three will be dark and cold.

****************************************

The conservation conundrum

A major underpinning of our understanding of physics has to do with symmetry and conservation laws.

Both have to do with order, balance, and the concept that you can't get something for nothing.  A lot of the most basic research in theoretical physics is driven by the assumption that despite the seeming complexity and chaos in the universe, at its heart is a deep simplicity, harmony, and beauty. 

The mathematical expression of this concept reaches its pinnacle in the laws of conservation.

You undoubtedly ran into conservation laws in your high school science classes.  The law of the conservation of matter and energy (you can move matter and energy around and change its form, but the total amount stays the same).  Conservation of charge (the total charge present at the beginning of a reaction is equal to the total charge present at the end; this one is one of the fundamental rules governing chemistry).  Conservation of momentum, conservation of spin, conservation of parity.

All of these are fairly well understood, and physicists use them constantly to make predictions about how interactions in the real world will occur.  Add to them the mathematical models of quantum physics, and you have what might well be the single most precise system ever devised by human minds.  The predictions of this system match the actual experimental measurements to a staggering accuracy of ten decimal places.  (This is analogous to your taking a tape measure to figure out the length of a two-by-four, and your answer being correct to the nearest billionth of a meter.)

So far, so good.  But there's only one problem with this.

Symmetry and conservation laws provide no explanation of how there's something instead of nothing.

We know that photons (zero charge, zero mass) can produce pairs of particles -- one matter, one antimatter, which (by definition) have opposite charges.  These particles usually crash back together and mutually annihilate within a fraction of a second, resulting in a photon with the same energy as the original one had, as per the relevant conservation laws.  Immediately after the Big Bang, the universe (such as it was) was filled with extremely high energy photons, so this pair production was going at a furious rate, with such a roiling sea of particles flying about that some of them survived being annihilated.  This, it's thought, is the origin of the matter we see around us, the matter we and everything else are made of.

But what we know about symmetry and conservation suggests that there should have been exactly equal amounts of matter and antimatter created, so very quickly, there shouldn't have been anything left but photons.  Instead, we see an imbalance -- an asymmetry -- favoring matter.  Fortunately for us, of course.

So there was some matter left over after everything calmed down.  But why?

One possibility is that when we look out at the distant stars and galaxies, some of them are actually antimatter.  On the surface, it seems like there'd be no way to tell; except for the fact that every particle that makes it up would have the opposite properties (i.e. protons would have a negative charge, electrons a positive charge, and so on), antimatter would have identical properties to matter.  (In fact, experimentally-produced antihydrogen was shown in 2016 to have the same energy levels, and therefore exactly the same spectrum, as ordinary hydrogen.)  From a distance, therefore, it should look exactly like matter does.

So could there be antimatter planets, stars, and galaxies out there?  Maybe even with Evil Major Don West With A Beard?

The answer is almost certainly no.  The reason is that if there was a galaxy out there made of antimatter, then between it and the nearest ordinary matter galaxy, there'd be a boundary where the antimatter thrown off by the antimatter galaxy would be constantly running into the matter thrown off by the ordinary galaxy.  So we'd see a sheet dividing the two, radiating x-rays and gamma rays, where the matter and antimatter were colliding and mutually annihilating.  Nothing of the sort has ever been observed, so the conclusion is that what we see out in space, out to the farthest quasars, is all made of matter.

This, though, leaves us with the conundrum of how this happened.  What generated the asymmetry between matter and antimatter during the Big Bang?

One possibility, physicists thought, could be that the particles of matter themselves are asymmetrical.  If the shape or charge distribution of (say) an electron has a slight asymmetry, this would point to there being a hitherto-unknown asymmetry in the laws of physics that might favor matter over antimatter.  This conjecture is, in fact, why the topic comes up today; a paper last week in Science described an experiment at the University of Colorado - Boulder to measure an electron's dipole moment, the offset of charges within an electron.  Lots of molecules have a nonzero dipole moment; it's water's high dipole moment that results in water molecules having a positive end and a negative end, so they stick together like little magnets.  A lot of water's odd properties come from the fact that it's highly polar, including why it hurts like a sonofabitch when you do a belly flop off a diving board -- you're using your body to break simultaneously all of those linked molecules.

What the team did was to create a strong magnetic field around an extremely pure collection of hafnium fluoride molecules.  If electrons did have a nonzero dipole moment -- i.e., they were slightly egg-shaped -- the magnetic field would cause them to pivot so they were aligned with the field, and the resulting torque on the molecules would be measurable.

They found that to the limit of their considerable measuring ability, electrons are perfectly spherical and have an exactly zero dipole moment.

"I don’t think Guinness tracks this, but if they did, we’d have a new world record," said Tanya Roussy, who led the study.  "The new measurement is so precise that, if an electron were the size of Earth, any asymmetry in its shape would have to be on a scale smaller than an atom."

That's what I call accuracy.

On the other hand, it means we're back to the drawing board with respect to why there's something instead of nothing, which as a scientific question, is kind of a big deal.  At the moment, there don't seem to be any other particularly good candidates out there for an explanation, which is an uncomfortable position to be in.  Either there's something major we're missing in the laws of physics -- which, as I said, otherwise give stunningly accurate predictions of real-world experimental results -- or we're left with the even less satisfying answer of "it just happened that way."

But that's the wonderful thing about science, isn't it?  Scientists never write the last word on a subject and assume nothing will ever change thereafter.  There will always be new information, new perspectives, and new models, refining what we know and gradually aligning better and better with this weird, chaotic universe we live in.

So I'm not writing off the physicists yet.  They have a damn good track record of solving what appear to be intractable problems -- my guess is that sooner or later, they'll figure out the answer to this one.

****************************************

The next phase

When I put on water for tea, something peculiar happens.

Of course, it happens for everyone, but a lot of people probably don't think about it.  For a while, the water quietly heats.  It undergoes convection -- the water in contact with the element at the bottom of the pot heats up, and since warmer water is less dense, it rises and displaces the cooler layers above.  So there's a bit of turbulence, but that's it.

Then, suddenly, a bit of the water at the bottom hits 100 C and vaporizes, forming bubbles.  Those bubbles rapidly rise, dispersing heat throughout the pot.  Very quickly afterward, the entire pot of water is at what cooks call "a rolling boil."

This quick shift from liquid to gas is called a phase transition.  The most interesting thing about phase transitions is that when they occur, what had been a smooth and gradual change in physical properties (like the density of the water in the teapot) undergoes an enormous, abrupt shift -- consider the difference in density between liquid water and water vapor.

The reason this comes up is that some physicists in Denmark and Sweden have proposed a phase transition mechanism to account for the evolution of the (very) early universe -- and that proposal may solve one of the most vexing questions in astrophysics today.

A little background.

As no doubt all of you know, the universe is expanding.  This fact, discovered through the work of astronomer Edwin Hubble and others, was based upon the observation that light from distant galaxies was significantly red-shifted, indicating that they were moving away from us.  More to the point, the farther away the galaxies were, the faster they are moving.  This suggested that some very long time in the past, all the matter and energy in the universe was compressed into a very small space.

Figuring out how long ago that was -- i.e., the age of the universe -- depends on knowing how fast that expansion is taking place.  This number is called the Hubble constant.

[Image licensed under the Creative Commons Munacas, Big-bang-universo-8--644x362, CC BY-SA 4.0]

This brings up an issue with any kind of scientific measurement, and that's the difference between precision and accuracy.  While we use those words pretty much interchangeably in common speech, to a scientist they aren't the same thing at all.  Precision in an instrument means that every time you use it to measure something, it gives you the same answer.  Accuracy, on the other hand, means that the value you get from one instrument agrees with the value you get from using some other method for measuring the same thing.  So if my car's odometer tells me, every time I drive to my nearby village for groceries, that the store is exactly eight hundred kilometers from my house, the odometer is highly precise -- but extremely inaccurate.

The problem with the Hubble constant is that there are two ways of measuring it.  One is using the aforementioned red shift; the other is using the cosmic microwave background radiation.  Those two methods, each taken independently, are extremely precise; they always give you the same answer.

But... the two answers don't agree.  (If you want a more detailed explanation of the problem, I wrote a piece on the disagreement over the value of the Hubble constant a couple of years ago.)

Hundreds of measurements and re-analyses have failed to reconcile the two, and the best minds of theoretical physics have been unable to figure out why. 

Perhaps... until now.

Martin Sloth and Florian Niedermann, of the University of Southern Denmark and the Nordic Institute for Theoretical Physics, respectively, just published a paper in Physics Letters B that proposes a new model for the early universe which makes the two different measurements agree perfectly -- a rate of 72 kilometers per second per megaparsec.  Their proposal, called New Dark Energy, suggests that very quickly after the Big Bang, the energy of the universe underwent an abrupt phase transition, a bit like the water in my teapot suddenly boiling.  At this point, these "bubbles" of rapidly dissipating energy drove apart the embryonic universe.

"If we trust the observations and calculations, we must accept that our current model of the universe cannot explain the data, and then we must improve the model," Sloth said.  "Not by discarding it and its success so far, but by elaborating on it and making it more detailed so that it can explain the new and better data.  It appears that a phase transition in the dark energy is the missing element in the current Standard Model to explain the differing measurements of the universe's expansion rate.  It could have lasted anything from an insanely short time -- perhaps just the time it takes two particles to collide -- to 300,000 years.  We don't know, but that is something we are working to find out...  If we assume that these methods are reliable -- and we think they are -- then maybe the methods are not the problem.  Maybe we need to look at the starting point, the basis, that we apply the methods to.  Maybe this basis is wrong."

It's this kind of paradigm shift in understanding -- itself a sort of phase transition -- that triggers great leaps forward in science.  To be fair, some of them fizzle.  Most of them, honestly.  But sometimes, there are visionary scientists who take previously unexplained knowledge and turn our view of the universe on its head, and those are the ones who revolutionize science.  Think of how Galileo and Copernicus (heliocentrism), Kepler (planetary motion), Darwin (biological evolution), Mendel (genetics), Einstein (relativity), de Broglie and Schrödinger (quantum physics), Watson, Crick, and Franklin (DNA), and Matthews and Vine (plate tectonics) changed our world.

Will Sloth and Niedermann join that list?  Way too early to know.  But just the fact that one shift in the fundamental assumptions about the early universe reconciled measurements that heretofore had stumped the best theoretical physicists is a hopeful sign.

Time will tell if this turns out to be the next phase in cosmology.

****************************************