Sciency Words: Blackbody Radiation

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


This is a thing you already know, even if you don’t know that you know it. In fact this may be one of the very first scientific discoveries you made as a child: when things get really hot, they glow. As they get hotter, they glow brighter and change colors from red to orange to yellow to white.

This concept is modeled scientifically using something called a blackbody. Imagine an object that is perfectly black, by which I mean that it reflects absolutely nothing and absorbs 100% of the light that falls upon it. No such object exists in real life (although vantablack paint comes close), but a good scientist knows how to imagine impossible things for the sake of a thought experiment.

Now if you were to observe this hypothetical perfectly black object in all wavelengths of light, you might find that it glows slightly in infrared. This is due to the blackbody’s internal heat. As the temperature goes up, the “shade” of infrared you see will start creeping towards the visible part of the spectrum.

Soon, the blackbody will glow dull red, then orange, then bright yellow. As the temperature continues to climb, green and blue will get into the mix, but when so many colors of light are mixed together you tend to see pure white. If you keep going, you’ll get into ultraviolet light and beyond.

I have to admit that I’m glossing over a lot of details here (click here or here for a little more technical info). The important thing to know is that under ideal conditions, when you’re dealing with a glowing hot substance or a glowing hot object (like a stovetop or the Sun or flowing lava), color serves as a useful gauge for temperature.

In the late 19th and early 20th Centuries, the study of blackbody radiation became a matter of paramount importance to science, in large part due to the demands of the Industrial Revolution. Industrialists really needed a way to measure the temperatures of things like molten iron or steel. Dipping a thermometer into molten metal wasn’t a practical option.

Scientists came up with ways to approximate blackbodies in real life (it’s really clever how they did this). Thing is in these laboratory experiments the light emitted by blackbodies did not behave the way it was supposed to, according to classical physics.

In 1900, physicist Max Planck came up with what must have felt like an inelegant way to model light’s weird behavior. For Planck’s model to work, he had to pretend light is sometimes a particle and sometimes a wave. That didn’t make any sense, but it worked. Then in 1905, Albert Einstein proved that no pretending was required: light really is both a particle and a wave.

And thus began the madness of quantum physics!

Sciency Words: Ylem (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, Y is for:


When George Gamow and Ralph Alpher were developing the Big Bang Theory (the actual theory, not the T.V. show), they needed a term for the bizarre form of matter they predicted would have existed in the early universe. They ended up picking the awkward-sounding word ylem.

In a 1968 interview, Gamow had this to say about the word’s origins: “You can look in the Webster dictionary. This is a word—I think it’s an old Hebrew word, but Aristotle was using it—in Webster dictionary (sic) is says ‘material from which elements were formed.’”

As a word nerd, I’m compelled to make two points of clarification before we can move on. First, I hate when people cite “Webster’s dictionary” as a source. Webster is not a trademarked name (Merriam-Webster is), so anybody can stick “Webster” on a dictionary and make it sound authoritative. Second, ylem does not come from Hebrew; the etymology traces back to the Greek word for matter (this according to my favorite real dictionary, The New American Heritage Dictionary, Fifth Edition).

Okay, word nerd rant over.

Aristotle did have something to say about the “fundamental matter” from which the elements formed. By elements, of course, he meant earth, fire, wind, and water. Aristotle’s term for this was proto-hyle. Over the millennia since Aristotle’s time, the hyle part of proto-hyle changed phonetically (Latin added an m, French dropped the h), and thus ylem entered English as a philosophy term.

Gamow and Alpher then turned it into a scientific term. Regardless of which dictionary they were looking at, for them it meant the primordial matter that existed after the Big Bang but before the chemical elements formed.

In a sense, this isn’t too far from the proto-hyle Aristotle was talking about. Except by elements, Gamow and Alpher meant things like hydrogen and helium, not earth or fire. Also, they could be a whole lot more specific about what ylem actually was: a highly charged plasma of protons, neutrons, and electrons that took roughly 400,000 years to cool off before it could start combining as atoms.

Next time on Sciency Words: A to Z, animals may not be able to talk, but they have other ways to communicate with us.

Sciency Words: WIMPs (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, W is for:


Approximately 85% of the matter in the universe is invisible; or if it’s not invisible, then it’s doing a really good job hiding from our telescopes. We call this invisible and/or well-hidden matter “dark matter.” We know about its existence only because of its gravitational effects, and also because of its childish taunting.

Scientists love acronyms, especially clever acronyms. There are many possible explanations for the dark matter phenomenon. One of them is a hypothetical subatomic particle called a WIMP: a Weakly Interacting Massive Particle.

Under the current standard model of particle physics, the universe is governed by four fundamental forces: gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Click here to learn everything you could possibly need to know about these forces.

If WIMPs exist, they interact with some of the fundamental forces, but not others.

  • Gravity: yes.
  • Electromagnetism: no.
  • Weak nuclear force: maybe yes.
  • Strong nuclear force: probably no.

Light is a result of electromagnetism. Since WIMPs don’t interact with the electromagnetic force, that would explain why we can’t see them.

But invisible particles like WIMPs aren’t the only possible answers to the huge question mark of dark matter. What about matter that’s visible but well hidden? Massive Astrophysical Compact Halo Objects (or MACHOs) are massive but faint objects in space, such as brown dwarfs, rogue planets, or black holes—the kinds of objects that would have a lot of gravity but would be difficult to spot with a telescope.

I have to imagine someone worked really hard to come up with MACHO as an acronym, so it would match well with WIMP. While there are other hypotheses out there, somehow the WIMPs vs. MACHOs debate seems to get the most attention. Which hypothesis does the best job explaining the dark matter mystery?

At this point, to the best of my knowledge as of this writing, physicists still cannot prove or disprove the existence of WIMPs. However, a recent astronomical survey seems to have ruled the MACHOs out of consideration. There simply cannot be enough black holes, brown dwarfs, and other stuff out there to account for 85% of the matter in the universe.

So the WIMPs haven’t won (at least not yet), but the MACHOs definitely lost. Big time. The MACHOs are losers. Big, fat losers. Hey, that’s not me saying that; it’s just what the science acronyms are telling us.

Next time on Sciency Words: A to Z, another reason to get mad at the I.A.U.

Sciency Words: Quantum (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, Q is for:


Quantum physics is the study of atoms and subatomic particles, and it get’s pretty weird. It’s almost as though all these quantum particles are playing a joke on us.

However, the quantum world isn’t completely loony. It’s not a place where anything goes. There are rules to how quantum particles behave; it’s just that these rules fly in the face of what we humans would call common sense.

But for our purposes here on Sciency Words, we won’t get into all those common-sense-defying rules. We’re more interested in the word quantum itself. How did this poor, innocent word get itself entangled with such a weird, wacky branch of science?

The story begins with Einstein (as so many things do). In one of his 1905 “Miracle Year” papers, Einstein needed a word to describe a particle of light. Einstein was arguing that light isn’t a continuous wave, as had previously been thought, but is actually made up of tiny particles (we now know light is both a particle and a wave at the same time, but I said we wouldn’t get into that common-sense-defying stuff).

Einstein chose the word quantum (plural: quanta) for his light particles. It’s a word closely associated to words like quantity or quantifiable. Basically, a quantum is something you can count. Specifically, it’s something you have to count in whole numbers, because you’re dealing with discrete units of a substance that cannot be divided into smaller units of the same substance.

Einstein’s light quanta would later be renamed photons, but the usage of quantum/quanta to describe other indivisible units at the atomic and subatomic level would continue.

Ultimately, this whole field of study would be dubbed quantum mechanics thanks to two papers published in 1925, the first by Max Born and Pascual Jordan, and the second by Max Born, Pascual Jordan, and Werner Heisenberg. At that time, all this quantum stuff was already pretty strange, and it would just keep getting stranger going forward.

And yet even today, modern quantum physics has stayed somewhat true to the root meaning of the word quantum, because it still deals with a lot of whole numbers. I should mention, of course, that there are plenty of non-whole numbers involved, such as Planck’s constant, and then there’s the whole matter of fermions and their non-integer spins (someone will yell at me in the comments if I don’t acknowledge that stuff).

But whole numbers and whole number ratios still play an extremely important—some might even say weirdly important—role in quantum physics, because you can’t have half an electron or half a photon or half a quark. You’re dealing with particles you must count in whole numbers, because they cannot be divided into anything smaller.

Next time on Sciency Words: A to Z, what do you do when a word means the opposite of what it’s supposed to mean?

Sciency Words: Negatron (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, N is for:


In 1896, J.J. Thomson discovered the electron: a subatomic particle with a negative electric charge. Then in 1932, Carl Anderson discovered a new kind of electron. It was exactly the same as the old one, except it had a positive charge.

Anderson decided to name this new kind of electron a positron, and he wanted to retroactively rename the old one a negatron.

When matter and antimatter particles like these get into arguments, they always end the same way: the particles annihilate each other. Which is why it’s so important for nuclear physicists to keep matter and antimatter apart.

Anyway, under Carl Anderson’s naming scheme, we’d still get to use the word electron, but electron would be sort of like a genus name, with positron and negatron being two species of electron. That’s a nifty way to think about matter/antimatter pairs, if you ask me. Too bad the idea didn’t stick.

Or so I thought….

To my surprise, I was able to find negatron in a dictionary—a standard dictionary, not even a special dictionary of science. To my further surprise, spell-check recognizes negatron as a word. According to Google ngrams, the word is still in use, and when I did a search on Google Scholar, I found a ton of papers—recent papers—using the term in relation to nuclear physics.

So that subatomic particle pictured above—whether it likes it or not, it really is a negatron.

Next time on Sciency Words: A to Z, it’s dangerous to name a concept before you fully understand it.

Sciency Words: Gravity (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, G is for:


We’ve all heard the story about how Isaac Newton discovered gravity.

But Newton’s discovery was not just that objects fall to the ground. Other people had noticed this before.

Newton’s real breakthrough was realizing that the same force which causes apples to fall also holds the Moon in its orbit around the Earth. Previously, it had been assumed that earthly physics here on the ground must be different from the celestial physics of the Moon, the planets, and the stars.

This is why Newton called his discovery the law of universal gravitation: because he believed his law must apply no matter where you are in the universe. Of course Newton didn’t know the planet Mercury was “breaking the law,” so to speak, nor did he know about black holes.

But I don’t want to get into Einstein and general relativity. Not today, at least. For today’s post, I just want to focus on the word gravity itself. Where did that word come from?

I used to think it was really cool how a scientific term like gravity had spread out and acquired additional shades of meaning in the English language. Think of a phrase like “the gravity of the situation,” where gravity means something like importance or seriousness.

But I’ve since learned that it actually happened the other way around. English originally borrowed gravity from French, and the word can be traced back to Latin. It originally meant something like dignified or serious. It could also mean weighty, in the sense of either metaphorical or literal weightiness.

But the idea of defining gravity as a physical force permeating the universe, causing objects to be attracted toward one another—that’s apparently an invention of Newton and his contemporaries. So now I think it’s really cool how science can take a word we already had and give it a whole new meaning.

Next time on Sciency Words: A to Z Challenge, we’ll talk about humans. Oh no, wait… that’s not my pick for the letter H. I have a much more interesting H-word to talk about; but humans will be involved.

The EM Drive: Is It for Real?

This weekend, I read the recently published paper on NASA’s “impossible” EM drive. Or rather, I read about the “closed radio-frequency resonant cavity” designed and tested by Eagleworks Laboratories (which is part of NASA).

Basically, this closed radio-frequency thing is a box with radio waves bouncing around inside it. Because of the box’s unusual shape, the radio waves end up pushing more on one side of the box than the other, which generates thrust. Supposedly. Even though that violates conservation of momentum.

This post is a review of the paper itself, and nothing more, because I’ve found that responsible scientists and quack scientists often reveal themselves in the way they write their papers. And whatever else might be going on with this physics-defying new engine design, the paper does not appear to be quack science.

  • Experimental methods and equipment are documented in meticulous detail, and sections are included describing “force measurements procedures” and “force measurement uncertainty.”
  • The researchers appear to be presenting all of their data, or at least they don’t appear to be deliberately hiding anything. They also make a point of explaining the data analysis techniques they used.
  • There’s a lengthy section on potential sources of experimental error. The paper explains how each possible error was corrected, or it tells us why the researchers believe the error is not statistically significant. The important thing is that these possible experimental errors are acknowledged to the reader.

Now I’m not a scientist or an engineer, so I can’t personally evaluate the data being presented here. But the fact that the Eagleworks team share so much information and go into such extensive technical detail is a good sign (even though it makes for rather dull reading).

It means they’re not asking us to just take their word for it. Anyone with the necessary knowledge, resources, and technical skills could evaluate the data for themselves or attempt to recreate the experiment in order to independently verify the test results. And that’s how science is supposed to be done.

That does not necessarily mean the EM drive works. A paper like this should be seen as the opening of a conversation. The Eagleworks team discovered something. Something that seems to violate conservation of momentum, or perhaps undermines the Copenhagen interpretation of quantum mechanics.

Follow up papers will continue the conversation, most likely by investigating those possible sources of error the Eagleworks team mentioned, or by trying to find sources of error the Eagleworks team may have overlooked. And my guess is that the conversation will end at that point.

But if it turns out the EM drive really does work, if the test results can’t be explained away by an experimental error, then the conversation will move on to trying to figure out what’s wrong with our current understanding of the laws of physics.

Regardless of how this plays out, it’s always good to see real scientific discourse in action.

Sciency Words: Gravity Waves vs. Gravitational Waves

Sciency Words MATH

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today, we’re looking at two terms that have almost nothing to do with each other:




What happens when you combine a 29 solar mass black hole with a 36 solar mass back hole?

Fb08 Black Hole

In this not-so-hypothetical scenario, 29 solar masses plus 36 solar masses equals 62 solar masses. The remaining 3 solar masses are converted into energy in the form of gravity waves. I mean gravitational waves.

I’ve been making this mistake a lot lately, ever since LIGO announced that it had detected gravitational waves for the first time. It’s just easier to say gravity waves. It’s two syllables shorter. Unfortunately, gravity waves and gravitational waves are completely different concepts.

What are Gravitational Waves?

Gravitational waves are part of relativistic physics. According to Einstein’s general theory of relativity, gravity bends space-time. Among other things, this bending causes everything from spaceships to planets to even light itself to follow curved trajectories in the presence of a gravitational field.

Extremely massive objects moving rapidly together, such as a pair of co-orbiting neutron stars or, in the case of the recent LIGO discovery, a pair of merging black holes, bend space one way then the other so violently that they produce a rippling effect in the fabric of space-time. We call these ripples gravitational waves.

What are Gravity Waves?

Gravity waves are part of a different field of physics called fluid dynamics. A few years ago, gravity waves were observed in the atmosphere of Venus, most likely due to air masses rising over mountainous terrain and falling down the other side. After these air masses return to their original altitude (return to a “state of equilibrium,” to use the technical lingo), they tend to bob up and down a bit, producing characteristic ripples in the atmosphere around them. We call these ripples gravity waves (specifically, they’re atmospheric gravity waves).

While this phenomenon has been observed on Venus and Titan, it is best understood here on Earth. Gravity waves are known to appear in Earth’s atmosphere, in lakes and oceans, at the interface between the atmosphere and the ocean… basically anywhere you find a fluid or fluid-like medium. Whenever a fluid returns to a state of equilibrium, either due to gravity or buoyancy, you can expect to see gravity waves.

One Wave is Not Like the Other…

Of course if you’re having a casual conversation about the LIGO experiment (who doesn’t have casual conversations about experiments in relativistic physics?) and you mistakenly say gravity wave instead of gravitational wave, I doubt anyone will be confused. Nine times out of ten, context will make it clear which kind of wave you meant. Just so long as somewhere in the back of your mind, you know there is a difference.