Review: Why Does E=mc^2? (And Why Should We Care?)

July 31, 2009

When I got my copy of Why Does E=mc² through the post, I was surprised how small it was. How the hell can you describe the foundations of the universe, explain the physics behind warped space-time, delve into wormholes and expect to come out the other side with an understanding of what Einstein's famous E=mc² means in a book half an inch thick? Surely the study of relativity requires a textbook the thickness of a tree trunk accompanied by a series of lectures taught by a grumpy professor wielding a stick of chalk!

Actually, as Brian Cox and Jeff Forshaw proves in this wonderful 264 page exploration of physics, Einstein's equation describes an elegant and succinct view of our universe, a view that is captured excellently in the text. In fact (and I haven't said this for a long time while reading a physics book), Cox and Forshaw's effort turned into something of a page turner.

Although people are generally adverse to seeing equations in popular science books, the authors realized that to give enough depth to describing how things work, equations are inevitable. I don't think it's a problem, and although the authors apologize for the math (polite lot, us physicists), they do provide hints for when you can skip ahead a couple of paragraphs. However, in those 'optional' paragraphs there's step-by-step, easy to follow micro-physics lessons that I enjoyed reading (and realized I'd forgotten a lot of my university relativity lectures). Some of it will be tough for non-scientist readers, but it's worth 'suffering' a few small equations as they tie together really nicely for Cox and Forshaw to explain their next big "wow" moment.

As you might have guessed, I enjoyed this book a lot, but the best bits were some of the real-world relativity applications they highlight. One example is a nice test of Einstein's theory the authors pick up on when describing experiments at Brookhaven National Laboratory in 1990.

Basically, space and time start to act a little strange for particles traveling at relativistic speeds, and for the lowly muon -- with a measly lifespan of 2.2 microseconds -- this is quite literally a life-saver (or life extender). If muons are accelerated at 99.94% of the speed of light around a 14-meter-diameter accelerator ring, one would expect these particles to complete only 15 laps before dying. But this isn't true.

In reality, they managed more like 400 laps, which means their lifetime is extended by a factor of 29 to just over 60 microseconds. This is experimental fact. --Cox & Forshaw, Why Does E=mc²?

Also, in the speeding muon's frame of reference, something very interesting happens to the way it experiences distance. To the muon, the diameter of the accelerator shrinks, allowing it to cover those 400 laps without breaking any laws of physics.

From this example alone, a huge wealth of physics has been explored and each point is singled out and expanded for Cox and Forshaw to explain further. "Welcome to the world of physics!" they exclaim, and I must admit, I was pretty excited about it myself. It's the enthusiasm for physics in Why Does E=mc²? that is key, reinvigorating relativity and presenting it in a modern and entertaining light.

But it doesn't stop at explaining speeding subatomic particles. The authors ask some basic questions and subsequently reveal the complexity of the structure of the universe. What is energy? (Not that New Age 'energy' nonsense.) What is spacetime? What is mass? (You just knew the Higgs Boson was coming, didn't you?) What powers the stars? All are fundamental questions with a common theme; E=mc².

All in all, this was a great read. Some portions might seem a bit too detailed if you already have a degree in physics, but I read all of it and even the advanced concepts wove neatly into the conversational tone of the book.

By the time you reach the last page, you realize just how beautifully complex, yet elegant, our universe really is. And it is all down to a simple equation that can be summed up like this:

"...energy and mass are interchangeable much like dollars and euros are interchangeable, and that the speed of light squared is the exchange rate."

What an awesome way of describing it...

You can find a copy of Why Does E=mc² (and why should we care?) by Brian Cox and Jeff Forshaw (published by Da Capo Press) on Amazon.com, and I'm pretty sure it will be flooding book stores imminently.

Scientist Accelerates Radio Waves Faster than Light...

July 01, 2009

...using this "gadget." What's that all about? Actually, I don't know.

What would happen if I walked into a physics conference and shouted, "I've discovered a phenomenon that travels faster than light!"?

1. I get laughed at.
2. I get thrown out.
3. I get ignored.
4. I get thrown in science jail for breaking the laws of physics.*

There might have been the chance that I'd made a huge discovery (perhaps I'd discovered the tachyon?), but I think I would have proven my statement before I made such a huge proclamation.

So yesterday, there was a buzz about a scientist, from Los Alamos National Laboratory, who managed to force the "phenomenon" of radio waves faster than the speed of light. Instantly, the physicist inside me nearly exploded with excitement. Sure, I've read papers that study quantum entanglement, where two particles will instantaneously change quantum states, thereby 'communicating' faster then light. I've also been neck deep in warp drives and wormholes recently, two other possible loopholes around Einstein's general relativity. But the "phenomenon" of radio waves? Wow...

*Thank you Lori for that little insight.