The Forge of God by Greg Bear, 1987

Something I picked up on Deviant Art, not related to this story except by feel.

Not a great book, but not a bad book either. Easy reading, entertaining, and some interesting ideas. The basic idea is how we would react if aliens (extra-terrestrials) showed up on our doorstep. And what if they weren't friendly?
    The story starts off with strange things happening: big rocks mysteriously appear in Death Valley and Australia, near Ayers Rock, and things come out and talk to people. So here's the first problem. This is common scenario in Science Fiction. The aliens have been listening to our radio and television broadcasts for years and from that they have figured out how to communicate with us using our own language. I wonder how feasible this is. Has anyone here on Earth tried to decipher a radio or television signal using only basic knowledge of physics, that is without knowing any of the internal structure of these signals? Of course it might be hard to find someone like that on Earth, but since everything is going digital, it might be interesting to see if any of our new digital whiz kids can decipher a TV signal from 50 years ago. We should be able to still generate such an animal, well, that is if the old analog equipment hasn't all been replaced by new, cheaper digital stuff.
    Even if you could decipher the signal and extract audio and video from it, would you ever be able to make sense of it?  Seems we had a heck of a problem with some ancient written languages until somebody discovered the Rosetta stone. I imagine any number of graduate students have earned their Phd's thinking about this kind of problem.
    I had a couple of minor problems with plot here too. Nobody investigates these big rocks. What are they made of? How did they get here? Is there any supporting structure? How deep do they go? What is the internal structure? Nobody investigates, nobody even asks the questions. That's okay. Big rocks mysteriously appearing in the desert is the least of our problems.
    Strange things continue to happen, but instead of presenting different facets of the same thing, they seem to be completely unrelated, or working at cross-purposes. It gets very confusing until we figure out there is a war going on and what we are seeing is fallout from that conflict. Now here is a good explanation for why none of this makes any sense. You never want to do anything obvious in a war, you want to confuse your enemy as much as possible, so throwing out deceptions and decoys is just part of the game.
    One faction in this war wants to "destroy all humans" (where have we heard that line before? Oh, wait, maybe this book is the originator of that idea). To that end they drop a couple of multi-megaton pellets made of neutronium on opposite sides of the Earth. One is made of regular neutronium, you know, the kind of stuff neutron stars are made of, and the other is made of anti-neutronium, which you would have to special order from the anti-matter galaxy on the other side of the universe. Contrary to what you might except, the anti-neutronium pellet does not immediately turn into energy when it contacts the atmosphere. It kind of starts boiling on the surface. Only so much matter can contact it at any one time, and that contact results in an immediate explosion which serves to push any nearby matter away, until the explosion subsides and then regular matter again comes into contact and the cycle continues. So it's giving off a heck of lot of energy in the form of radiation, but it doesn't all go boom at once.
    Because these pellets are so dense they fall right through surface of the earth and into the core. Regular matter is about as dense as air compared to these pellets, so dirt, rocks and magma are no obstacle at all. They would fall right through the planet and out the other side, except for gravity. Gravity from the Earth attracts them, and they attract each other, so they fall into a decaying orbit around the center of the Earth. The Earth is like air to them so they glide through it easily, but it does exert some drag, much like an air exerts drag on an airplane, so they are slowing down. Eventually they will both come to a stop at the center of the Earth and at that point the pressure of the Earth and their mutual gravitic attraction will cause them to fuse and, because one is matter and the other is anti-matter, detonate. So it's like a time bomb with a fuse measured in days, which means the plot needs to move along pretty quickly now.
    Anyway, that's how you blow up a planet. Meanwhile somebody puts some hyrdrogen bomb making factories at the bottom of the deepest trenches in the ocean and they proceed to electrolyze the ocean to generate hydrogen to make bombs. They release the oxygen which bubbles to the surface. They release so much oxygen that fires start burning out of control. I heard once that if the percentage of oxygen got up above 30% we would start to see spontaneous combustion of ordinary combustible materials. We never really find out who (or what) is behind all these evil deeds, but this bit really sounds superfluous. I mean if you can lay your hands on a multi-megaton blob of neutronium, do you really even need to mess with something as mundane as a hydrogen bomb?
    There is also the bit about spaceships coming up from under water with no explanation of how they got there. I suppose if you could put a big rock down in the middle of the desert without being detected, you could put a little old spaceship under the sea, but if you can do that, why do you  even need a spaceship?
    But like I said, it was easy reading and entertaining, and I haven't even mentioned the spiders from Mars.

P.S. The author reminds us that the solid crust of the earth is very thin, like one percent of the distance to the center. That is like a covering of pasteboard on a twelve inch globe.