Resonant Cavity Thrusters

EmDrive. Q drive. Cannae drive. All of these are a class of devices known as resonant cavity thrusters, and for the past few years they’ve been popping up in the media from time to time.

What’s the big idea?

Take an ordinary household magnetron (you’ll find one in every microwave oven). Use it to pump microwave radiation into a resonant chamber of a certain shape (a metal box that’s wide at one end and narrow at the other.)

Turn it on and voilà: even though nothing is emitted from the system, you’ll detect a very small anomalous force pushing the chamber.

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A Slice of Pi

A quick story belatedly written for Pi Day 2015.

Although man has long known that the world is larger than he can imagine, it is only recently that scientists have begun to hypothesize that the entirety of our universe is but a small subset of an unfathomable existence. A group known as the CC: Underground, an eclectic assortment of cosmologists, philosophers, and computer scientists, has for several decades believed that our reality is merely a simulation in some indescribable computer.

A splinter faction within the CC: Underground further believes that, through focused investigation and experimentation, we could gain control of the computer simulation that is our reality, and signal whoever is running the simulation. It is to this group that I belong.

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5 Misconceptions about the Moon

The Moon holds a special place in our imaginations — and why not? Along with the Sun and the five classical planets, the Moon is one of the few celestial objects whose apparent motion in the night sky can be seen.

You can even see its disk with the naked eye — and unlike the blinding white-hot disk of the Sun or the barely-discernible-to-human-vision disks of Jupiter or Venus, what a disk is the Moon! Throughout history, we’ve stared at the shadows and highlights of the lunar surface and envisioned everything from a man to a magic rabbit.

In case you’re wondering, that’s Mercury, not the Moon.

It’s not surprising, therefore, that we’ve built up some misconceptions about the Moon. Here are the five misconceptions about the Moon that I find to be the most prevalent, most fun, most frustrating, or just the most annoying.
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Last Physicist’s Waltz

An entry for Flash! Friday – vol. 2-29. The prompt for the week was “patience”.

I’ve heard it said the English slow waltz is the most beautiful to behold. Dancers in constant motion, pairing, twirling to the music. They swirl across the dance floor like snowflakes in a winter breeze.

Thorium-232 has the slowest of waltzes. Invisibly, infinitesimally, its nuclei dance to the rhythm of the weak nuclear force. With a half-life of fourteen billion years, the nuclei step out their slow, patient Geiger rhythm.

Impatient men failed to see the natural beauty of the slow waltz of atoms. Impatient men upped the tempo, changed the dance, taught Thorium-232 to tango. Nuclei whipped into a frenzy, gyrating helter-skelter across the landscape.

I’ve heard it said the English slow waltz is the most beautiful to behold. In the aftermath of the last dance, the nuclear beat goes on. The snow falls furiously now. There’s no one left but the atoms, and me; all dressed up to enjoy the dance in quiet solitude.

Faster than Slower than Light

In the last article on Tachyon Rocketry, it appears that even a rocket propelled by tachyons is limited by the lightspeed barrier.

The problem is that our bodies (and our starship) are made of electrons, quarks, and other particles with real, non-zero mass. In the context of faster-than-light tachyons, such particles are known as bradyons or tardyons, and are always constrained to travel slower than light.

What if we got rid of the starship altogether? Instead of traveling the galaxy the slow way, what if we could just transmit ourselves to our destination? Sort of like Star Trek’s transporter technology?

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Tachyon Rocketry

In my last article, I fiddled with an interstellar spaceship propelled by a photon rocket. The maximum speed (more correctly, delta-v) of a rocket depends on the exhaust velocity of its propellant. Since we know of nothing that travels faster than light, photons seem to be the best possible propellant.

But what if our propellant traveled faster than light? Particles that travel faster than light are generally called tachyons, and if they exist, they have some very strange and inconvenient properties. (In fact, FTL Pizza recently closed its Tachyonic Anti-Telephone Booth because kids kept making prank calls to Albert Einstein.)

As the saying goes, “relativity, causality, and FTL: pick any two”…
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Photon Rockets for Interstellar Travel

Say you want to build an interstellar rocket. Cool beans. What’s the best way to go about it? Well, to get the highest possible delta-v, you want the highest possible exhaust velocity for your rocket propellant.

So what’s the fastest thing in the universe? Unless you’re living in a universe with FTL, that would be light, which travels at about 300,000,000 meters per second. We’ll use a jet of photons (otherwise known as a beam of light) to propel our starship.

The problem? Photons are the fastest things in the universe, but the thrust-to-power ratio of a photon rocket is pretty low. How low? In the words of the Atomic Rocket engine list, “three hundred freaking megawatts” for every Newton of force.

In other words, the maximum output of a typical nuclear power plant would (given a 100% efficient photon rocket) just barely be able to levitate a measly paper clip against Earth’s gravity.

Well darn.
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