Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

Co-author Jenn Dlugos and I are also doing some extremely ridiculous things over at Drinkstorm Studios, including our award-winning webseries, Magicland.

There are also a full 100 posts right here in the archives, and feel free to drop me a line at with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Physics
What I’ve Learned:

The Doppler Effect: yet another reason to run from screaming children.
“The Doppler Effect: yet another reason to run from screaming children.”

Most science happens in a laboratory or a particle accelerathingy or inside the brain of some bushy-eyebrowed theory geek. The applications don’t make it far into the real world. Like, why do we never see nonhomologous recombination in the newspapers? Or a cartoon starring Schrodinger’s cat?

Which would presumably be a fan of lasagna, but not so much of Mondays. Just based on previous observations of animated feline behavior.

But once in a while, we’re thrown a bone — a science bone — and we get to see what the eggheads are talking about in their fancy journals and proceedings. Like the Doppler effect, which we can observe on a regular basis — or daily, depending on your neighborhood — and also hear about on the local six o’clock news. That’s more public exposure than Jeremy Piven gets.

Although, to be fair: it’s Jeremy Piven. So.

Anyway, the Doppler effect has to do with waves, and the way they change in frequency relative to motion. Sound waves, for instance. Imagine a toddler in a mall throwing a tantrum, and screaming “MOMMY!” at one-second intervals. As toddlers do.

Now, if you’re moving toward the child — maybe you’re “MOMMY”, and you have the binky that will end this meltdown — the sound of those one-per-second screams will reach your ears faster. If you could run fast enough (and please do; we’re trying to shop here, ma’am) in the direction of the kid, you’d notice the frequency of those screams getting closer together. The child’s still shrieking them once a second, but you’re plowing toward them, so you get to the next one faster than, say, some guy just sitting in the food court with breadsticks shoved in his ears.

That change in frequency is the Doppler effect, and it’s a result of relative movement between the source and the receiver of the waves in question. So if you’re sitting still — because “Mommy’s tired”, obviously — but the squirt comes screaming toward you, the effect will be the same. On your ears, anyway. If not necessarily your Xanax prescription.

The Doppler effect works in the receding direction, too. If your relative motion is away from a wave source, the frequency will decrease as you move further away. With sound waves, pitch varies with frequency, which is why sirens — or toddlers — coming toward you sound high-pitched as they approach, then normal as they pass and lower-pitched as they speed past.

But autotuning ambulance noises and screaming tots isn’t the only trick up the Doppler effect’s sleeve. Light is a wave, too — depending on the time of day and which theoretical physicist you’re talking to — and astronomers can use observations of starlight to determine whether those stars are moving toward us or away from us. But rather than changing pitch, light undergoing a Doppler effect shifts color instead. So light sources coming at us skew toward blue wavelengths, or are “blueshifted”, while light from stars streaking away shows a “redshift”.

And what about the Doppler effect horning in on the local news? Well, radar is another type of electromagnetic wave, and works just the same as light and sound. That “Doppler radar” the weatherman gets so excited about determines the speed and direction that storms are moving by measuring the Doppler effect on radar waves bounced around the atmosphere.

There are plenty more examples, but you get the idea. Also, that kid’s not going to cram his own binky in his mouth, apparently, so maybe you could take care of that now, mommy. Mommy. MOMMY!

Image sources: CK-12 (it’s the Doppler coppers!), CinemaBlend (pouty Piven), Ramblin’ Mama (kid, keening), Twilight Language (randy radar reading)

· Write a comment
· Tags: , , , , , , , ,

· Categories: Physics
What I’ve Learned:

Double-slit experiments: where two holes make a 'whaaaat?'
“Double-slit experiments: where two holes make a ‘whaaaat?'”

Have you ever dated someone who wouldn’t make a damned decision? Where should we eat? “I dunno.” Which movie are we watching? “Whichever.” Should we get married and have kids and live happily ever after? “Meh. We’ll decide later.”

Well, that’s what the universe is like. And the double-slit experiment is one of the clearest proofs.

Think about light. Light is kind of an important part of the universe; it’s the whipped cream on the cosmic sundae. Without light, there’d be no suntans or iPads, and we’d all be stubbing our toes in the dark every time we turned around.

So light is kind of a big deal, and physicists have studied it for hundreds of years. Back in the 1600’s, Isaac Newton — he of the fabulous hair and apple-induced concussions — thought that light was made up of tiny little particles, which eventually became known as photons.

And for a hundred-plus years, the universe said, “Yeah, sure, whatever.”

Every time scientists studied light, it behaved like a beam of little particles. Up until the early 1800s, that is, when physicist Thomas Young shone light through a pair of slits in a barrier, and watched the universe get wishy-washy.

Here’s the issue: if light is made up of particles — like a stream of paintballs, say — and you fire a bunch of those at a wall with two holes in it, then you’ll end up with just two spots of paint on the other side, right behind the holes.

Also, you’ll have a very messy wall. Mom is going to be pissed.

But what if light was made up of waves? Imagine water flowing through a dam with two holes. The water would only make it through the gaps — but then it would spread out, with the ripples from each side flopping into each other, creating a network of peaks and troughs called an interference pattern. That’s the pattern Young saw in his double-slit experiment, and he proclaimed that light is composed of waves.

To which the universe replied, “Eh, maybe.”

This is where things get really goofy. First of all, it’s not just light that behaves in this waffly way; double-slit experiments work with electrons, atoms and some molecules — or basically all the stuff our toes and iPads and suntans are made of.

But worse — what happens when you push, for instance, a single electron at a wall with two slits? Why, you get a single spot on the other side, just like the damned thing was a microscopic stupid paintball.

The universe doesn’t know which tie looks better. You decide.

And if you shoot a bunch of electrons at those slits, one by one — do you get two patches of light on the other side, since those individual electrons clearly act like particles? Nope. Eventually you get the very same interference pattern you would if you opened the floodgates up front.

Now the universe is just shrugging at you. And laughing behind your back.

In many ways, double-slit experiments — both physical and thought-experiment variations like those proposed by Richard Feynman — have helped to shape modern ideas about quantum mechanics, and the probabilistic nature of reality those theories suggest.

All of which is to say, if you’re ever stuck on a really important life decision like where to live or which job to take or whether that toe you stubbed in the dark might be broken — don’t ask the universe.

It hasn’t made a damned decision in three hundred years.

Actual Science:
Florida State University / Optical Microscopy PrimerThomas Young’s double-slit experiment
University of Oregon / 21st Century ScienceTwo-slit experiments
PhysicsWorldFeynman’s double-slit experiment gets a makeover
Physics arXiv Blog / MediumPhysicists smash record for wave-particle duality
io9An experiment that might let us control events millions of years ago

Image sources: Physics World (double-slit pattern), SweetJack (splatter wall), GearCrave (“Which tie, universe?”), QuickMeme (unsure Fry [standing in for the universe])

· Write a comment
· Tags: , , , , , , , , , , ,