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 secondhandscience@gmail.com with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Physics
What I’ve Learned:

Relativity: you can't choose your family, but you can pick your physics.
Relativity: you can’t choose your family, but you can pick your physics.

I’ve learned a little about the theory — actually, theories — of relativity.

(Obviously only “a little”; I’ve never learned a lot about anything.)

Of course, I got a little confused about the word “relativity”. Seeing as how it sounds like “relatives”, I initially thought the physics professor was talking about my family. The parallels are so strong, in fact, it took me three lectures to figure out the problem. Maybe your relatives are different. Judge for yourself:

First, there are two kinds. You’ve got “general” relativity, and then there’s relativity that’s… “special”. Like Aunt Eunice, who leaves her girdle by the table after family dinners. Or cousin Gene, whose clan has watched “A Christmas Story” several thousand too many times.

(Apparently, there’s now a new-ish thing called “doubly special relativity” or “extra-special relativity”. Some physicists must have talked to Nana after her three helpings of rum fruitcake.)

Just as families make no sense, neither do the two names for types of relativity. “General” relativity actually only covers one specific thing: gravity. I thought this meant the gravitation of parents and grandparents around you when you visit for Christmas, asking things like, “You’re not wearing that, are you?” And “When are you going to find a job?” And “Who ate all my damned fruitcake?

I found out later it was a different kind of gravitation, and apparently it doesn’t work the way Isaac Newton or anyone else thought it did. The way Einstein figured gravity led to some pretty oddball predictions about the universe: spacetime must be curved rather than consistent, gravity can slow time and bend light, and black holes could exist that suck up all matter and light nearby.

These were all pretty outlandish notions when they were hypothesized back in the early 20th century. But as we’ve sorted out ways to precisely measure and explore such things, they’ve all turned out to be real. Who’s loopy on fruitcake now, classical physicists?

Of course, that leaves “special” relativity to explain everything else — a common occurrence at my family’s holiday parties. If you want to hear what’s wrong with kids today, where you ought to put your money or how the “gubment” ought to be run, just pull up a chair (and a tall stiff eggnog) and listen to the “special” relatives dish out a dose of “wisdom”.

(Naturally, they know as much about these topics as I know about… well, science. Which is scary. I’m surprised most of them manage to put on their pants in the morning.)

As I’ve mentioned before, special relativity isn’t about such things, though. (Thank goodness.) Instead, it’s a description of how spacetime — the woven-together fabric of time and three-dimensional space — works, and how things we used to believe were fundamental actually change based on perspective. Like an event happening at the same time according to two people, but sometime else to an observer in relative motion. Time slows down and objects seem shorter, the faster they go. And the big one that ties mass and energy and the speed of light (squared) all together: E = mc2.

Physicists glommed onto special relativity soon after Einstein first proposed it in 1905, because it fit with certain experimental observations better than Newton’s old laws — and it was useful in the bizarro, whacked-out, very “special relative” worlds of nuclear physics and quantum mechanics. General relativity took longer, but finding black holes and pulsars and other weird cosmic schmutz it predicted helped to solidify it, too.

So relativity isn’t about relatives, really. But a lot of it is strange, much of it is “special”, and most of it is, like, a hundred years old. So it’s really not that different. And it’s all around us in the form of spacetime and gravitation, so keep an eye out for relativity at your family gatherings over the holidays.

Just watch out for Nana. She’s a mean fruitcake drunk.

Image sources: Science News (relativity clocks), Southern Belle View (the family that Ralphies together…), Daily Mail UK (drunk grandma), Sur Fisika (Einstein v. Newton)

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· Categories: Physics
What I’ve Learned:

Special relativity: out with the aether, in with the aother.
“Special relativity: out with the aether, in with the aother.”

On the heels of the holiday season, you may have recently witnessed instances of “special relativity”. Grandma’s secret-recipe fruitcake pucks. Your uncle’s uncomfortably falsetto rendition of “O Holy Night”. Cousin Lem’s drunken faceplant into a bowl of Christmas bisque.

Happily, that’s not the only sort of special relativity. One hundred and ten years ago, Albert Einstein (with a little help from his friends) developed a theory that explained the behavior of things that travel near the speed of light. Like New York City taxis, or Usain Bolt. Or, you know, light.

This theory was needed because by the late 1800s, scientists had figured out that their plain old regular-speed relativity — based on work by Galileo and Newton, among others — wasn’t always getting the job done. This old school theory, called Newtonian relativity or Galilean invariance, because see the previous sentence, sport, said there is an “absolute space” and an “absolute time”, in which everything happens. And by that time, it also included an “absolute reference frame”, a universally unique point of view from which electromagnetic wave properties like the speed of light could be accurately measured.

Problem was, experiments suggested that if that uniquely-accurate reference frame (known as the “aether”) existed, all measurements made in labs were consistently in agreement with it. In other words, all those labs were stationary with respect to this spatial frame of reference. Which would be super, if we didn’t know that the Earth is constantly swooping around the sun (and the sun around the Milky Way, and the Milky Way hurtling through the universe), so it’s not really “stationary” compared to anything but itself.

Einstein dropped this “aether” concept down the nearest aelevator shaft, and that was just the beginning. He also decided that space and time were two great tastes that taste greater together, and mushed them together into something called “spacetime”. And he said no matter how fast you’re going (or not), the speed of light will always look the same. That let a whole bunch of crazy — but later experimentally verified — cats out of the physics bag. For instance:

Under special relativity, two people moving at different speeds may watch the same event happen, but observe it occurring at different times. And not just because one of them has TiVo, either.

If you watch two clocks — one moving and one sitting still — the moving clock appear to go slower. (And if it’s moving while you’re sitting in your office at ten minutes til five on a Friday afternoon, it’ll appear to go reeeeeeeeally slow.)

Mass and energy are equivalent, as given in Einstein’s famous special relativistic equation, E = mc2. This is obvious to anyone who’s eaten a four-ounce chocolate eclair and felt the kajillion-calorie jolt to their metabolism as the mass is converted to energy… and then seen six pounds of flab appear on their ass as it converts back to mass.

(I don’t know why it gets bigger in the conversion. What am I, some wild-haired German genius math guy?)

Basically, Einstein’s special relativity theory made some predictions crazier than drunk old Cousin Lem on an eggnog bender, but they turned out to be true where Newtonian relativity did not. Either theory will get you through the day for normal stuff — but if you’re zooming around near the speed of light, then you’d damned well better listen to Einstein.

He may not be your relative. But believe me — he’s special.

Actual Science:
LiveScienceWhat is relativity?
American Museum of Natural HistorySpecial relativity
HowStuffWorksHow special relativity works
io9Get pelted every day with particles that confirm special relativity
The Physics ClassroomRelativistic length contraction

Image sources: QuickMeme (it’s all relativity), Telegraph (UK) (blurry Bolt), Food Navigator (food faceplant), London Evening Standard (an eclair and present danger)

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· Categories: Astronomy, Physics
What I’ve Learned:

Gravitational lensing: mirror, mirror in the sky; show me what's behind this guy
“Gravitational lensing: mirror, mirror in the sky; show me what’s behind this guy.”

If you’ve ever sat behind a really tall person at a movie, then you know the infuriating problem of not being able to see something on the other side of a solid object. At the theater, you probably deal with this in the usual ways — hoping the heighty person slouches in their seat, or spontaneously loses six inches of height, or their head explodes like in that Scanners movie.

But astronomy tells us there’s another viable option, known as gravitational lensing. All you have to do is push the movie a few million light years away, and make that big fat head in front of you as dense as a ten-billion star galaxy.

It’s a little complicated. I’ll explain.

One of the (now-famous) predictions of Albert Einstein’s general theory of relativity is that space (really spacetime, but who’s counting?) is curved, and that hugely massive objects with lots of gravitational force will further warp that curving. So if a celestial light source — like, say, a quasar — lies behind an enormous gravitational well such as a galaxy, the light from the quasar would get curved around the galaxy and slingshot out the other side.

It might appear that the light source lies beside the big heavy thing in the way, because the light doesn’t bend all the way back to the middle. And if the source is directly behind the obstacle, the light could take more multiple paths around it — left, right, up, down, south by southwest — and appear more than once on our side. It could even form a full ring of light all around the object in the middle, weirdly indicating that the thing producing the light isn’t anywhere around the obstacle at all, but directly behind it.

I know, right? It’s spooky. Real call is coming from inside the house stuff.

Because Einstein described relativity, and was a generally awesome dude, the light rings caused by gravitational lensing are called “Einstein rings”. There are very few complete rings — caused by a massive energy source directly behind a star or galaxy — but hundreds of partial rings, multiple-image systems and other gravitational lensing events have been observed. One of the most impressive, called Einstein’s Cross — because, again, cool smart guy — consists of four “bent” images of a way-distant quasar curved around a still-way-distant-but-not-as-way-distant galaxy in between.

It’s like having a head in the way, but still seeing the movie in double-stereo-vision. Because astronomy makes everything better.

So what do you need to make gravitational lensing work? First, a source of some kind of energy. Many of the known ones work in visible light, but any kind of electromagnetic energy will do in a pinch. The universe isn’t picky.

The energy source has to be ridiculously strong, though, because you’ll need to see the signal from way far away. Not just from down the block, or from that window in your attic, either. Instead, from billions of light years away. Which is kind of a big deal.

Why so far? Because you then need to find an incredibly massive object to plop between you and the energy source to produce the gravitational lensing. A bowling ball isn’t going to do it. A star might, if it’s in precisely the right orientation. A whole galaxy of stars would be better. Or you could try Nicki Minaj’s ass. It’s big enough to attract most of the pop culture paparazzi into a close orbit, apparently. Maybe it could work; I don’t know.

The point is, you’ll only see gravitational lensing by throwing that hypermassive whatever between you and and the signal. And then you can watch that gravity well bend electromagnetic waves like Beckham, off a straight line and down to your eyes.

So maybe it won’t help you the next time you’re blocked at the movies. But gravitational lensing could show you a star behind another star some day. And really, isn’t that how the movie industry works in the first place?

Image sources: Cosmic Chatter (Einstein ring), Slate (big head at movie theater), Disease Prone (Scanners head), SlamXHype (rocket-powered Minaj)

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