Sciency Words: The Replication Crisis

Hello, friends!  Welcome back to Sciency Words, a special series here on Planet Pailly where we talk about new and interesting scientific terms so we can expand our scientific vocabularies together!  In this week’s episode of Sciency Words, we’re talking about:


There’s a quote that I hate which is frequently misattributed to Albert Einstein: “The definition of insanity is doing the same thing over and over again and expecting different results.”  Why do I hate this quote?  First off, as a matter of historical record, Einstein never said this.  But more importantly, doing the same thing over and over again to see if anything different happens is a surprisingly good definition of science.

Or it least it should be, which brings us to this week’s Sciency Word: the replication crisis.  As this brief introductory article retells it, the replication crisis began with “a series of unhappy events” in 2011.  Certain “questionable research practices” were exposed, along with several cases of outright fraud.  I’m going to focus on just one very noteworthy example: the American Psychological Association published a paper titled “Feeling the Future,” which claimed to show statistically significant evidence that human beings have precognitive powers.

When other researchers tried to replicate the “Feeling the Future” experiments, they failed to find this statistically significant evidence.  However, according to this episode of Veritasium, the American Psychological Association had a policy at the time that they would not publish replication studies, and so they would not publish any of the research debunking the original “Feeling the Future” paper (I do not know if they still have that policy—I would hope that they do not).

The act of repeating experiments to see if anything different happens is a crucial part of how science works.  Or rather how it should work.  But this is not being done often enough, it seems.  And on those rare occasions when replication studies are performed (and published), a shocking number of high profile research turns out to be non-replicable.  This article from sums up just how bad the replication crisis is:

One 2015 attempt to reproduce 100 psychology studies was able to replicate only 39 of them.  A big international effort in 2018 to reproduce prominent studies found that 14 of the 28 replicated, and an attempt to replicate studies from top journals Nature and Science found that 13 of the 21 results looked at could be reproduced.

That same article calls the replication crisis “an ongoing rot in the scientific process.”

But as I’ve been trying to say in several of my recent posts, science is self-correcting.  With the introduction of metascience—the scientific study of science itself—there is some hope that the root causes of the replication crisis can be identified, and perhaps changes can be made to the way the scientific community operates.

Sciency Words: Quantum Entanglement

Hello, friends, and welcome to a special Halloween edition of Sciency Words!  Today, we’re talking about the spookiest of scientific terms.  And that super spooky term is:


Quantum mechanics is the study of the tiniest of tiny things in our universe: things like atoms and quarks and electrons.  And these super tiny things do some pretty weird stuff, if our current mathematical models are to be believed.  Stuff that seems to defy our human notions of common sense.

In the 1930’s, when quantum theory was still brand new, Albert Einstein did not approve of all that common-sense-defying stuff that quantum mechanical models were predicting.  So in 1935, Einstein and two of his colleagues, Boris Podolsky and Nathan Rosen, published a paper that was supposed to prove quantum theory was incorrect, or at least that it was woefully incomplete.

The Einstein-Podolsky-Rosen paper (or E.P.R. paper, as it’s now commonly known) didn’t quite get the job done.  Quantum theory survived the attack.  In response to the E.P.R. paper, Erwin Schrödinger (of Schrödinger’s cat fame) wrote a letter to Einstein.  It was in this letter, from Schrödinger to Einstein, that the word “entanglement” was first used in reference to quantum theory.  Well, actually, Schrödinger used the word Verschränkung, a German word which translates into English as “entanglement.”  (The relevant section of Schrödinger’s letter is quoted in this article from The Stanford Encyclopedia of Philosophy.)

Entanglement refers to the way a pair of quantum particles can interact with each other and then remain “entangled” with each other after their interaction is over.  If you measure the quantum state of one entangled particle, the other will instantaneously change to match.  This implies that entangled particles can somehow exchange information at faster-than-light speeds.  As Schrödinger wrote in his letter, this is not just a weird quirk of quantum theory; it’s the “characteristic trait” that makes quantum mechanics so radically different from classical physics.

Einstein was still not happy.  Neither was Schrödinger; however, as I’ve come to understand the story, Schrödinger was able to set his personal feelings about quantum theory aside and continue his research.  Einstein, meanwhile, kept trying to prove quantum theory was wrong until the day he died.

You might even say the idea of quantum entanglement haunted Einstein for the rest of his life.  In 1947, in a letter to another physicist named Max Born, Einstein referred to entanglement as spukhafte Fernwirkung, a phrase which is commonly translated into English as “spooky action at a distance.”  (The relevant section of Einstein’s letter is quoted in this book.)

Thus, quantum entanglement is the spookiest scientific term.

Sciency Words: The Chronological Protection Conjecture

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about all that weird terminology scientists like to use.  Today on Sciency Words, we’re talking about:


English theoretical physicist Stephen Hawking had a lot to say about time travel.  There are plenty of Hawking quotes out there that seem to suggest that time travel is possible, or at least that it’s not totally impossible.  This seems odd to me, because when you read Hawking’s actual research, he is about as anti-time travel as a physicist can get.

As we discussed in last week’s episode of Sciency Words, Einstein’s theory of general relativity would apparently allow time travel to occur.  Relativity permits space-time to twist around itself into something called a “closed timelike curve.”  Hawking could not allow that to stand, and in 1991 he published this paper introducing something he named the “chronological protection conjecture.”

Hawking summarized his conjecture as follows: “The laws of physics do not allow the appearance of closed timelike curves.”  If a closed timelike curve ever did start to form, Hawking goes on to explain, then some other physical law—vacuum polarization, repulsive gravity, quantum effects—would get in the way, causing the closed timelike curve to die before it was ever truly born.

Based on my read of Hawking’s paper, it sounds like a closed timelike curve might (might!) still be possible inside a black hole.  But if you’re a time traveler trapped inside a black hole, you can’t do much to interfere with the course of history, can you?  Thus, regardless of what may or may not be happening inside black holes, the rest of the universe is still safe from time travel paradoxes.

So if Hawking’s physics is so adamantly against closed timelike curves, why did Hawking make so many public statements teasing us with the possibility of time travel?  Well, Hawking was a big fan of science fiction, and he seems to have loved many of the usual Sci-Fi tropes, including time travel.  The laws of physics may not allow for time travel, according to Hawking, but stories about time travel are still fun.  Maybe Hawking didn’t want to take that fun away from us.

Speaking of time travel, are you a fan of time travel adventure stories?  The kinds of stories you might see on Doctor Who or The Twilight Zone?  Then please check out my new book, The Medusa Effect: A Tomorrow News Network Novella, featuring time traveling news reporter Talie Tappler and her cyborg cameraman, Mr. Cognis.

Sciency Words: Closed Timelike Curves

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those weird words scientists like to use.  Today on Sciency Words, we’re talking about:


Austrian-born logician and mathematician Kurt Gödel was one of Albert Einstein’s closest friends.  At Princeton’s Institute for Advanced Study, the two were known to take long walks together, discussing all sorts of strange and wonderful things, no doubt.

As science historian James Gleick tells the story in his book Time Travel: A History, Gödel presented Einstein with a very special gift for Einstein’s 70th birthday.  It was the kind of gift only a person like Einstein would appreciate: a series of mathematical calculations.  Specifically, these were calculations based on Einstein’s own theory of general relativity which showed that yes, time travel is possible.

Gödel’s calculations were officially published in this 1949 paper.  Now I won’t try to explain Gödel’s math because a) I don’t really understand it and b) it’s not really important for the purposes of a Sciency Words post.  What is important for our purposes is that Gödel’s 1949 paper introduced a new concept called “closed timelike curves.”

Well, technically speaking, Gödel used the term “closed time-like lines,” not “closed timelike curves.”  But as Google ngrams shows us, the hyphen quickly dropped out of “time-like,” and by the 1990’s, “curves” beat out “lines.”  So today, closed timelike curves is the most broadly accepted way to say what Gödel was trying to say.  The term is also commonly abbreviated at C.T.C.

In short, a closed timelike curve is a path through space and time that circles back to its own beginning.  As I understand it, it would take a stupendous amount of force to twist space-time around itself in this way.  You’d need the extreme gravitational force of a black hole—or perhaps something even more extreme than that—in order to make a closed timelike curve happen.

But it could happen.  As Gödel demonstrated in 1949, general relativity would allow a closed timelike curve to exist, or at least relativity does not forbid such things from existing.

So time travel is possible.  It may not be anywhere near practical, but it is at least possible.

Speaking of time travel, are you a fan of time travel adventure stories?  The kinds of stories you might see on Doctor Who or The Twilight Zone?  Then please check out my new book, The Medusa Effect: A Tomorrow News Network Novella, featuring time traveling news reporter Talie Tappler and her cyborg cameraman, Mr. Cognis.

Inverted Space (Tomorrow News Network: A to Z)

Hello, friends, and welcome back to the A to Z Challenge.  For this year’s challenge, I’ve been telling you more about the universe of Tomorrow News Network, my upcoming Sci-Fi Adventure series.  In today’s post, I is for:


On ancient Earth, there were three great revolutions in physics.  First came Isaac Newton and his laws of classical mechanics.  Then came Albert Einstein with his theories of special and general relativity.  And lastly, near the end of the 21st Century, Dr. Harold Strickland published his theory of inverted space.

In the simplest possible terms, inverted space is a place where the laws of physics are reversed.  It’s a universe of anti-physics, if you will.  Dr. Strickland believed that in order for our universe to exist as it does with the laws of physics that it has, then an equal and opposite universe must also exist to create balance.

One might expect such a radical and bold theory to spark debate and controversy among the scientific community.  It did not.  Few took any notice of Strickland’s work at the time.  It wasn’t until many years after Strickland’s death that he received the recognition and credit he deserved.  What changed?  The discovery of faster-than-light technology.

You see in our universe, nothing can travel faster than the speed of light; in inverted space, nothing can travel slower than light.  Of course, jumping into inverted space is dangerous.  The laws of physics are reversed, after all.  The attractive forces that hold atoms and molecules together become repulsive forces.  Molecular and atomic decoherence can occur within seconds!

But a quick jump in and out of inverted space is relatively safe, and a sequence of quick, carefully calculated “inversions” can allow a spacecraft to cross the vast distances of the galaxy.

It’s also worth noting that in inverted space, time runs backwards instead of forwards.  This troubled Dr. Strickland, yet it was an unavoidable consequence of his math.  If you were to jump through inverted space and then jump back to your starting location, would you not arrive before you departed?  Would this not violate causality and create a time travel paradox?

As it turned out, nature has its own ways of preventing paradoxes, even if Dr. Strickland couldn’t find them in his math.  When you push two magnets together, either positive to positive or negative to negative, the magnets resist.  They repel each other, and the harder you try to push them together, the harder they push back.

Something similar occurs in inverted space.  If you jump through inverted space and then attempt to jump back to your original location, your spacecraft will be deflected off course.  Your past and present selves seem to repel each other, like magnets, and so this is known as the chronomagnetic effect.

Nothing in the theory of inverted space predicted this chronomagnetic effect would exist, and nothing about the theory of inverted space can help explain why it occurs.  So while inversion theory is more advanced than relativity theory or classical mechanics, it still does not provide a complete picture of how the universe works.

For a complete picture of how the universe works, you’d have to learn about chronotheory, the science of time travel.  And next time on Tomorrow News Network: A to Z, we’ll talk about the people who use chronotheory to bring you tomorrow’s news today.

Sciency Words: Time’s Arrow

Hello, friends, and welcome back to Sciency Words!  Each week, we take a closer look at the definition and etymology of a science or science-related term.  Today’s Sciency Word is:


Which way is time going?  Prior to the 1890’s, no one would have asked such a silly question.  Time is time.  Everything about time is self-evident.  Why would anyone question it?

But then in 1895, H.G. Wells introduced the concept of time travel to the readers of adventure fiction.  And then in 1915, Albert Einstein started treating time as a variable, rather than a constant, as part of his general theory of relativity.  In his book Time Travel: A History, science historian James Gleick explains:

Millennia had gone by without scientists needing special shorthand like “time’s arrow” to state the obvious—the great thing about time is that it goes on.  Now, however, it was no longer obvious.  Physicists were writing laws of nature in a way that made time directionless, a mere change of sign separating +t from –t.

British astronomer Sir Arthur Eddington gets credit for introducing the “arrow of time” as a conceptual metaphor.  Eddington’s arrow points from the past toward the future.  Unless it doesn’t.  Depending on what sort of physics problem you’re trying to solve (or what sort of Sci-Fi story you’re trying to tell), it may be more convenient to imagine time’s arrow pointing from the future toward the past.

In 1927, in a series of lectures at the University of Edinburgh, and then later in a book titled The Nature of the Physical World, Eddington made three key points about time’s arrow, which I’ll paraphrase as:

  1. Gosh, time’s arrow sure does seem real to us humans.
  2. And common sense reasoning insists that time’s arrow must always point in the same direction.
  3. But when you do the math, you’ll find that none of the laws of physics actually require time’s arrow to exist, except one.

That one exception is the second law of thermodynamics, which tells us that the entropy of a closed thermodynamic system will inevitably increase with the passage of time.  So time’s arrow must always point in the direction of increasing entropy.

Of course a lot of people remain skeptical about time travel.  The Time Machine by H.G. Wells is a fine piece of fiction.  As for general relativity, treating time as a variable (rather than a constant) might help make the math work, but that doesn’t necessarily mean variable time is a real phenomenon.

Still, thanks in larger part to Arthur Eddington and his arrow metaphors, the question “which way is time going?” no longer sounds like total nonsense.

Next time on Planet Pailly: have we discovered a second planet orbiting Proxima Centauri?

Origin Stories: Who Invented Time Travel?

Welcome to Origin Stories, a monthly series here on Planet Pailly where we take a look at the origins of popular Sci-Fi concepts.  Today on Origin Stories, we’re looking at the origins of:


If I ever have a time machine—a real, working time machine—the first thing I’d do is go back in time and meet the person who invented time travel.  We do know who that person was.  His name was H.G. Wells, and he was the author of the classic science fiction novella The Time Machine.

Wells got the inspiration for The Time Machine from an unlikely source.  As science historian James Gleick explains in his book Time Travel: A History:

At some point [Wells] sees a printed advertisement for a contraption called Hacker’s Home Bicycle: a stationary stand with rubber wheels to let a person pedal for exercise without going anywhere.  Anywhere through space, that is.  The wheels go round and time goes by.

Of course there had been time travel-like stories before.  Remember the ghosts of Christmas Past, Present, and Future.  Remember the story of Rip Van Winkle, who found himself suddenly in the future after a really long nap.  Or remember Mark Twain’s A Connecticut Yankee in King Authur’s Court, in which a man from Connecticut gets bonked on the head and wakes up to find himself in the distant past.

But H.G. Wells was the first to take the idea of time travel semi-seriously.  He was the first to try to dress up the idea with scientific and technological jargon.  And in my opinion, no other author has handled time travel so clearly and concisely as Wells did.

The protagonist of The Time Machine, a man of science referred to only as “the Time Traveler,” first explains to a group of friends that we exist in a world of not three dimensions but four.  Everything that exists in this universe has the qualities of “Length, Breadth, Thickness, and—Duration.”  The Time Traveler’s friends then raise all the objections Wells’ readers might have had, and the Time Traveler explains all those objections away in exchanges like this:

“But,” said the Medical Man, staring hard at a coal in the fire, “if Time is really only a fourth dimension of Space, why is it, and why has it always been, regarded as something different?  And why cannot we move in Time as we move about in the other dimensions of Space?”

The Time Traveler smiled.  “Are you sure we can move freely in Space?  Right and left we can go, backward and forward freely enough, and men always have done so.  I admit we move freely in two dimensions.  But how about up and down?  Gravitation limits us there.”

“Not exactly,” said the Medical Man.  “There are balloons.”

“But before the balloons, save for spasmodic jumping and the inequalities of the surface, man had no freedom of vertical movement.”

In other words, we can only move freely in the third dimension thanks to technology—hot air balloons, airplanes, rockets….  Therefore technology may also give us the power to move freely through the fourth dimension of time.

Of course H.G. Wells didn’t actually believe in time travel.  As James Gleick goes on to say, all Wells was trying to do was “gin up a plausible-sounding plot device for a piece of fantastic storytelling.”  But as it would turn out a decade or so later, Wells was not too far off from the truth.  Physicists like Albert Einstein and Hermann Minkowski were soon treating time as variable, rather than a constant.  No, Einstein and Minkowski didn’t build any bicycle-like contraptions in their basements, but the notion of time as the fourth dimension—that soon became serious science.

Time travel has always been my favorite subgenre of science fiction.  It has been ever since my Dad first introduced me to Doctor Who.  I realize time travel isn’t everyone’s cup of tea, but personally I enjoy the kinds of brain-twisting puzzles that a good time travel adventure presents.  It’s the reason I still love Doctor Who, and it’s the reason time travel features so prominently in my own writing.

So if I ever have my own time machine, the first thing I’d do is go back in time to meet H.G. Wells.  I think I owe Mr. Wells a thank you.  

Sciency Words: Gravity Waves vs. Gravitational Waves

A few years back, I made a bit of a fool of myself in front of a professional physicist from LIGO.  You see, I kind of have a reputation, both online and in real life.  I’m the Sciency Words guy.  I’m the guy who knows stuff about scientific terminology.

So it’s pretty embarrassing when I get my scientific terms mixed up!  For today’s episode of Sciency Words, I’d like to share with you the two terms I got confused about so that the next time you meet a physicist from LIGO, you won’t make my mistake.


Gravity waves have to do with fluid dynamics: the movement of liquids and gases.  As an example, imagine an air mass being blown up and over a mountain range. Once over the mountains, that air mass will start to fall downwards again due to the force of gravity.

But of course air masses don’t sink straight down like lead weights.  Air has a lot of buoyancy, so that air mass will bob up and down for a while until it settles into a stable equilibrium.  This bobbing up and down motion will produce ripples in the atmosphere, and those ripples are called gravity waves.

Gravity waves have been observed both in Earth’s atmosphere and Earth’s oceans.  They’ve been observed on other planets as well.  Basically any time part of a liquid or gaseous medium is forced upwards, you can expect gravity to pull it back down again, producing gravity waves.


Gravitational waves have to do with Einstein’s theory of general relativity.  As an example, imagine two black holes spinning rapidly around each other. Even if you’re watching this from a safe distance, you might notice the combined gravitational attraction of those black holes grows stronger and weaker in a regular, oscillating pattern.

Well, actually you probably won’t notice that.  Even in the most extreme circumstances, those oscillations in gravity are barely detectable.  But they do happen.  The LIGO Project confirmed that in 2015 (the news wasn’t announced until 2016).

French theoretical physicist Henri Poincaré gets credit for coining the term gravitational waves (ondes gravifiques in French).  He first wrote about them in 1905, around the same time Einstein was formulating his theory of special relativity.  I’m not sure who coined the term gravity wave, but English mathematician George Biddle Airy was the first to mathematically describe gravity waves in 1841.

My mistake was asking a physicist who studies gravitational waves for LIGO a question about gravity waves in the atmosphere of Titan.  I mean, it’s an understandable mistake, getting these two terms confused—unless you’ve been introduced as an expert on scientific terminology!!!  Then it’s super embarrassing!!!

P.S.: As it so happens, I got the chance to meet up with that same LIGO physicist once again this week.  She was giving a presentation at Princeton University.  Don’t worry.  I didn’t embarrass myself too much this time.  I’ll tell you more in Monday’s post!

Sciency Words: The Anomalous Precession of the Perihelion of Mercury

If you’re anything like me, you’ve probably looked at planetary orbits and asked yourself: why does Mercury’s perihelion precess so anomalously? That simple, straightforward question is the subject of this week’s edition of Sciency Words.

Sciency Words is a special series here on Planet Pailly where we take a look at a new and interesting scientific term so we can all expand our scientific vocabularies together. Today’s term is:


I know, it’s a bit of a mouthful, but trust me… this anomalous precession thing is pretty cool.

Gravity According to Newton

Back in the 17th Century, Isaac Newton found a mathematical way to describe gravity, and his mathematical description worked for everything from falling apples to the orbits of all the planets. Well, all the planets except Mercury.

Mercury’s perihelion (the point where Mercury is as close to the Sun as it gets) moves.  That in and of itself isn’t so strange, but the perihelion moves a tiny bit faster than it should according to Newton.
Mercury’s perihelion (the point where Mercury is as close to the Sun as it gets) moves. That in and of itself isn’t so strange, but the perihelion moves a tiny bit faster than it should according to Newton.

The mystery of Mercury’s orbit (or the “anomalous precession of the perihelion of Mercury,” to use the technical lingo) baffled scientists for centuries. That is until Albert Einstein came along.

Gravity According to Einstein

Einstein’s theory of general relativity postulates that space and time are not separate entities but two aspects of what physicists now call space-time. General relativity predicts that the force of gravity causes space-time to bend or warp.

Needless to say, the Sun has a lot of gravity. Turns out that the warping of space-time around the Sun precisely explains Mercury’s weird orbit. In fact, every planet experiences some degree of this anomalous perihelion thing. It’s just that, because Mercury is so much closer to the Sun, the warping effect is significantly more noticeable.

Fe12 Time Warp

This is perhaps the planet Mercury’s greatest contribution to science. The anomalous precession of Mercury’s perihelion provided one of the earliest proofs that general relativity—and all the wibbly-wobbly, timey-wimey stuff that comes with it—is not just science fiction.

Fe12 Albert and Isaac


The 200-Year-Old Mystery of Mercury’s Orbit—Solved! from io9.

The Mysterious Orbit of Mercury from The Great Courses.

Accounting for General Relativity at Mercury from The Planetary Society.

Artsy Science: Einstein and the Secret of the Imagination

Artsy ScienceToday’s post is the first in a collection of posts on the artistic side of science.  Through both art and science, we humans try to make sense of the world around us, and the two fields have a lot more in common than you might expect.

* * *

For this initial post in Artsy Science, I want to share some quotes from one of the 20th Century’s most famous musicians: Albert Einstein.  You may not have known that Einstein was a dedicated violinist.  He never traveled anywhere without his most beloved instrument.  He also played the piano, and there are many apocryphal stories about him solving complex mathematical puzzles while practicing his music.  To Einstein, art and science were merely two separate branches of the same tree.

Here is what Einstein had to say about art and science:

  • Music does not influence research work, but both are nourished by the same sort of longing, and they complement each other in the release they offer.
  • I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
  • The most beautiful experience we can experience is the mysterious. It is the source of all true art and science.

Most of Einstein’s discoveries were not made in a lab but in his own mind.  After reading about vexing mysteries uncovered by other scientists, Einstein would sit back and try to picture these mysterious phenomena from new perspectives, and then later attempt to describe in scientific terms what he had imagined.  Einstein called these “thought experiments.”

In an age when our society has become rigidly fact oriented, often intolerant of daydreamers, free spirits, and other such time wasters, we should remember Albert Einstein’s work and what it reveals about the power of the human imagination.  And maybe we should all take a few moments to pause, close our eyes, and engage in a few “thought experiments” of our own.

P.S.: If your thought experiments lead you to any important discoveries, please share them in the comments below!