Will, your timeline states that antimatter power plants will be available (and apparently commonplace) in 2180.
A century after the global deployment of fusion, new forms of power production are becoming necessary in order to cope with the ongoing rise in energy demands on Earth and elsewhere. A new generation of power plants is becoming available, capable of harnessing the energy released in matter/antimatter collisions. The reactions involved are 1,000 times more powerful than fission produced in nuclear power plants and 300 times more powerful than nuclear fusion energy.*
Antimatter power plants are a really cool idea, and I've been tying myself in knots trying to figure out how they would work so I can include them in my own timeline. However, I'm can't really seem to figure out how antimatter power will ever be economically practical. The reference doesn't really address that either.
I assume that your timeline has some sort of factory to generate antimatter in kilogram quantities (or at least gram quantities). The problem with that is that to produce x grams of antimatter requires at least the amount of energy in x grams of antimatter. This page on Project Rho implies that this is a law of physics, inherent to antimatter production, not some sort of technical limitation that we can overcome. What I'm trying to say is that any hypothetical antimatter factory would be better off simply using its energy to power industries and whatnot directly, instead of making antimatter. If you want antimatter power plants, you have to "mine" the stuff. (To use an analogy with today's technology, what if we had to synthesize uranium in a particle accelerator? Nuclear power plants would be utterly useless, right?)
I can see two ways around this using the known laws of physics. For one thing antimatter does occur naturally in the Solar System, with Saturn's radiation belt being one of the best sources. But even Saturn produces less than a milligram of antimatter per year! I don't know how much antimatter is already there, but this comment suggests that the Earth's antimatter belt has 160 nanograms of antiprotons and a refill rate of 2 nanograms per year. If we apply this ratio to Saturn, we can assume that there are 20 grams of antimatter in Saturn's radiation belt.
Using the e=mc^2 formula, we get e=0.04*( 3E+8 )^2. (0.04 because 20 grams of antimatter+20 grams of matter = 40 grams or 0.04 kilograms). This comes out to 3.6 petajoules, which is puny. All the antimatter in Saturn's radiation belt could power a single 1-gigawatt power plant for about six weeks. Then we would have to wait for decades to have more antimatter. I suppose that hypothetically, an antimatter source orders of magnitude larger could exist somewhere, but it sure wouldn't be in the Solar System, because we likely would've already noticed.
What these power plants could be doing is, instead of using pure matter-antimatter annihilation (as the timeline claims) is to use antimatter as a catalyst and/or trigger for conventional nuclear/fusion fuel, which might give you more bang for the buck. If this is the case, the timeline should say so.
If Will or anyone else can figure out a solution, I'd love to hear it. The timeline should also be reworded to address this. (I'd personally go with the antimatter catalyst/trigger idea, but it's not my timeline.)