So in my post from the other week I alluded to the idea that negative mass is absurdly awesome, and that I may talk about it in the future. Well, folks, the future is now. So let's get to talking about negative mass.

First of all, negative mass falls under the category of exotic matter, which is pretty much filled with stuff, that, while not mathematically impossible, is unlikely to exist and has never been observed anywhere in the universe. This does not stop exotic matter from being the most interesting kind of matter (it may actually be part of the reason it is so cool). So, as we know, all matter seems to have mass, a property intrinsic to matter, and, according to the Standard Model, imparted upon the matter via interaction with the Higgs Field (that's what all the Higgs Boson hullabaloo was about a while back—that was the boson which would act as the "force carrier" for the Higgs Field, and give objects mass (and, by extension, gravity))...

If you haven't played any of the Mass Effect games, you really should. However, sometimes the physics of the very wonderfully developed fictitious future galaxy doesn't quite hold up. In this case, the very effect they've named the games after. Now, I'm not going to discuss Element Zero or the idea of manipulating mass (which is the titular Mass Effect), but rather how this manipulation doesn't make possible many of the things they claim it does. But first, let's start with a primer for those of you whop haven't played the games, or didn't pay a whole lot of attention to the sciency stuff in them:

Picture yourself on the surface of the Earth (or in a boat on a river). Now, if you were to toss something up into the air, it would eventually be pulled back down, due to the effects of gravity. Obviously, this force is not indomitable, as we've escaped the Earth's gravitational well many a time (most recently, when we sent something awesome to Mars—because orbit doesn't really count as escaping the Earth's gravity). In fact, if you were to toss something up with enough force, it would fly away forever, never to be seen again. The speed you instantaneously imparted on that object when you threw it is the Earth's escape velocity. Now, let's say we increase the mass of the Earth to that of Jupiter, but keep the size the same (we make the Earth much, much more dense). Now, in the instant before you were liquified by it, you'd notice the gravity has become much, much stronger than it was. This makes perfect sense, as gravity is a property of mass.

Matter. It's basically everything. Anything you can see and touch (except holograms), and some things that you can't see or touch, is matter. There's plain old boring matter, which is all the things you see around you all the time, and is composed of atoms you see on the periodic table. But then there's all that cool weird matter (not necessarily strange or exotic matter, because those are actual, real names of types of matter). Since you're already probably pretty familiar with prosaic matter, having been interacting with it all your life, let's talk about some of the more interesting matter.

Every object* that is above 0 Kelvin (read: everything in the universe) radiates somewhere on the electromagnetic spectrum. Stick with me, and I'll explain why. But first, every object* also absorbs light somewhere along the electromagnetic spectrum. For example, let's take glass. Now, in the visible spectrum (390<λ<700 nm), glass doesn't really absorb, reflect, or emit light (which is why it's transparent). This is due to a quantum mechanics phenomenon called "quantization." Essentially, electrons and the like can only exist in discrete levels of energy, and nowhere in between (like steps on a staircase—you can be on one step or another, but not between them (at least not without falling)). This is odd, and somewhat counter-intuitive because it doesn't appear to occur at the macroscopic level (our daily lives), but it's completely true (as far as we know). When an object absorbs light, it's because that specific wavelength of light is enough to jump an electron...

One thing you should know about space: it's huge. Mind-bogglingly huge. If you were to think of the biggest thing you could possibly imagine, it would still be more than a billion times bigger than that (and don't say you imagined infinity, because you can't. And stop being clever). The problem with just saying "the universe is huge" is that it doesn't really convey the distances involved. We can talk all we want about light-years and parsecs (unit of distance, not time, sorry George Lucas), but it doesn't really mean much. They're just words. And, as wonderfully evolved as language is, a lot of scientific terms fail to covey conceptual content with them, because our brains simply didn't evolve to deal with this sort of stuff. So this Friday, I'm going to try to take a stab at this comprehension.

Let's begin with a journey through time (and space, if you live any distance from Cambridge). The year is 1909, nearly seventy years since the death of John Dalton, the physicist who pioneered atomic theory. It's a little over ten years since Sir Joseph John Thomson (J.J. Thomson—not to be confused with the other J.J. Thomson, who was a philosopher) discovered the electron, and created the "plum pudding" model of an atom. This model stated that atoms were a more or less homogeneous mix of positively-charged and negatively-charged particles (protons and neutrons respectively). Electrons were the negatively-charged ones, because Ben Franklin said so in the eighteenth century (simplification, and possibly slightly farcical). Atoms were more of less the coolest kid in town when it came to physics, but scientists still didn't really know all that much about them—the "plum-pudding" model was mostly a wild guess.