"Why Does E = mc²?" by Brian Cox & Jeff Forshaw

Why Does E=mc2? (And Why Should We Care?) was another recommendation from Dan Satterfield.  I happened to read it after the two Frank Close books, which was serendipitous for me -- learning stuff in the first two seemed to help me ease through this one just fine.  I learned the simple basics of the E=mc2 equation years ago, even though I wasn't taught why it meant what it did, much less the many other implications behind the equation and the research that led to it.

I had a hard time really internalizing "spacetime" as a measuring unit. First, I had to understand the thought experiment about two people watching the faster moving of the two, and considering their own perspectives about who is moving and how quickly.  Next, I had to accept that no one person "standing still" is truly still, given how the Earth moves, inside the Solar System that moves, inside the Milky Way that moves.  Last, that light travels one speed only.  At this point, we're forced to figure out what other aspect has to change in order for the original two-people-moving scenario to add up.

But getting the point of spacetime is key to understanding that Einstein proposition about clocks running slower as they themselves move faster, as best exemplified by the Twins Paradox.  Also, seeing things as measured by spacetime is what makes something like a "warping" of it to shorten travel times theoretically possible.

The most serious sit-up-and-notice moment I had was reaching this point:  "... the earth is doing nothing more than falling in a straight line around the sun.  It is just that the straight line is in a curved spacetime, which manifests itself as a (nearly) circular orbit in space".  I actually had to put the book down at this point and ponder things for several minutes.  I had to put it into my own words for my brain to process it:  "The earth is falling straight at the sun, but since the sun itself is moving, the earth's fall path gets pulled along in the direction that the sun itself is falling (toward the center of the Milky Way).  But if you only consider things from the perspective of the sun being still, the earth's movement seems to be the circular orbit".  I had heard before about the light-bending experiment using an eclipse, but this explanation really made me grasp it.

"Neutrino" by Frank Close

On a recommendation from Dan Satterfield, I picked up "Neutrino" by Frank Close, hoping to get an idea of what a neutrino actually is.  I was not disappointed.

I always enjoy a historical narrative of what leads to a given discovery.  Most of the book is that story as it unfolded for the neutrino particle, from its imagined existence to its discovery to its acceptance.

I never quite understood how a particle could be "predicted" by a theory.  Frank explains early on how a hypothesis under consideration prompted the need for another piece, a new and unknown piece, one that seemed to correctly explain the overall picture if that piece is included.  Thus, it is predicted.  Then came figuring out how to prove it did exist after all.

The amount of effort and time involved in finding the neutrino came across to me as if it was the '60s space program condensed into a much smaller group of  partipants.  I felt a profound level of respect when considering just how perseverant these people were in trying to prove its existence.

Also covered is the evolution of the thinking behind how the sun powers itself, of which the neutrino played a part.  The starts and stops of this process made for some neat historical reading, with names I knew and many that I did not.

Lastly, I never truly understood the point of particle accelerators.  Now I do.

"Antimatter" by Frank Close

As I was looking for Frank Close's "Neutrino", based on a recommendation from Dan Satterfield, I found his other book "Antimatter", so I picked up both.  As Antimatter was published first, I tackled it first.

Seeing a sequence of discoveries, and how one step steers into another step, is something that I enjoy.  Frank's history on the process that discovered the positron fits this liking very well.

He explains how antimatter can be created and contained.  Seeing both aspects further shows why it's not realistic to view antimatter's possibilities as a fuel, much less a weapon.  His key point is that creation and containment require such high energy costs that they are just not feasible to try to use as fuel or weaponry.

Since a single matter + antimatter collision annihilation only creates a tiny amount of energy, you'd need a lot of antimatter to start with.  Therefore, you'd have to contain a lot of it.

A magnetic field can trap charged particles, so it could keep charged antimatter contained.  This requires a strong magnetic field to contain a large amount of these charged antiparticles, thus a high energy cost.

Neutrally charged antihydrogen molecules could mean more antimatter without the strong containment field... but then how do you contain it at all?  It was only the charged aspect of the antiparticles that allowed a magnetic field to trap them in the first place.

So, it takes lots of energy to make antimatter, and more energy to contain it, and you need lots of the (anti)stuff in order to accomplish the use case (fuel, weapons).  It's just not reasonable to think it can be practical.

This book explained all this in very approachable terms and pace.