Physics is about extremes. Even by Newton's time we had figured out the rules governing most things we can see with our eyes, so physicists for the last 200 or so years have been left with the task of investigating things that are either too small, too far away, or too hard to detect with our meagre five senses. The first half of the 20th century was devoted to small things. Thomson discovered electrons, Rutherford discovered atoms, Marie Curie discovered radioactivity, nuclear bombs were made. Bohr's and Schrodinger's atomic models remain largely unchanged today. Nuclear physics was born, space exploration was still a fantasy. It was all about the small guys.
Tides turned when the Cold War started. The space race captured the imagination of big and little kids everywhere. Astronauts became the coolest people on the planet. Men went into space and walked on the moon. Space stations orbited the earth. When we were little, my dad made a set of bookshelves for my brother where the endpieces were shaped like rocketships launching into space. Go figure, my brother grew up to be a space physicist and spends his time launching things into space (although not bookshelves). NASA and its counterparts in Japan (JAXA) and Europe (ESA) have successfully sent probes to every planet, some of their moons, and a handful of meteors, meteorites and dwarf planets. There's still a lot more to be learned about these bodies, but the tides have turned once again.
On July 21, NASA's space shuttle program came to a controlled stop at the end of the Kennedy Space Center's runway. As the Atlantis landed for the last time, the reins of human space flight were turned over to the likes of Richard Branson and friends until the International Space Centre de-orbits in 2020 and humans come back to earth. Since its first manned flight in 1958, NASA has spent $470 billion, at an average of 1.2% of the US annual budget. That's a serious commitment to looking at big, far-away things. The knock-on effects of NASA spending were huge and impossible to quantify, but it unquestionably inspired two generations of scientists, engineers and other dreamers in the US and beyond. NASA really did boldly go where no man had gone before. NASA's most recent mission, the Juno probe's trip to Jupiter, successfully launched last Friday. The Juno probe will take a polar orbit to look at the biggest planet in our solar system, a huge gas planet that resembles the sun except for the obvious lack of fire. An interesting mission, but we are entering the post-astronaut era. The "wow" factor has waned. Although they strapped a couple of smiling Lego people to the probe in an attempt to attract a younger audience, Lego people are simply too big. Our imaginations have moved on.
On the other end of the size spectrum, the Higgs boson and other particles currently being sought by the large Hadron collider (LHC) have attracted an astounding amount of media attention since the accelerator was turned on in September 2008. Even on the subatomic front there has been considerable rivalry between the big guys and the small guys. There’s more than one way to look for subatomic particles. Colliders such as the LHC make atoms move really really fast and then crash them into each other, hoping that not only does the hubcap pop off, but that the seat leather comes off too. These theoretical, subatomic particles should also exist in space, and probes outside the earth’s atmosphere can look at waves from distant objects that would be destroyed by the time they reach the earth. So we should also be able to detect Higgs in space, as Miss Piggy has known from the start. NASA’s FERMI satellite is currently doing just that. The race is on. Even people who traditionally focus on big things are investigating subatomic structure. The coming decades will push the limits of our understanding of all things small. I’d better start building some atomic structure bookshelves.