Well, the impact of the large chunk of rock/ice/cryogenic gas could have had enough impact energy that half way around the planet the shock waves met and created the massive volcanic outpouring from a already stressed mantle. This would have done a double whammy, the shock wave and resultant tsunami would wipe out pretty much all ecosystems on half the planet facing the impact point, and the volcano would have dumped massive amounts of cooling aerosols and done a similar thing on the other half.
That only the smaller animals that were either able to adapt, or were long lived and did not have too specialised a diet to eat varieties not the regular fare, and also those that were all mostly ocean living were the survivors points to there being a long period of both low temperature, poor climate and very likely massive changes to local environments.
error bars on the age measurements mean that you could have this with the 2 events compounding each others effects and leading to a long recovery period and massive changes in lifestyle pattern across the globe.
As far as I know memory is not stored as a particular location, or a specific neuron set, but more like a hologram, with the memory being more created by the linkages formed between neurons, and then being kept by being refreshed and with new memories creating additional pathways.
Thus I see that your method, while being able to erase particular memories, will also have a very unwanted side effect of also erasing or modifying the rest of the memories stored in this region, and thus will prove less than ideal in action. The action of thinking of a bad memory can also have some side effects, as association will also cause additional recollections which might be desired, and the erasure will more than likely destroy or modify them as well.
With the number detected recently, it seems that pretty much every star will have a planet or two around it, and systems consisting only of a star and nothing else will be very rare, probably only something that occurs in close binary systems, where the 2 stars rotate around a common centre of gravity that makes any close in orbits unstable, though you will find that there will be planets at a distance where the effect of the 2 masses revolving around each other can approximate to a point source.
About the only stars that will not have planets are those that were supermassive, and which went bang as a supernova, vaporising any close in planets in doing so. Even those will have far placed outer planets that would have survived the cooking, though the gas giants would be much smaller from having the majority of gas boiled off.
Lot of granites do have quite high gold concentrations inside, but are not at all economical to mine because they are so hard, and the energy required to grind them to powder to enable the gold to be extracted is more than the value of the gold. Thus most gold comes from softer dolerites where it is easier to crush them, and we do not really mine seawater even though it has a similar gold content, as concentrating the gold is hard in that case. However a lot of the flakes in rocks are also various forms of mica, which can look like gold and silver flakes.
Just a quick thing on Radon is that it is present in all underground mines, as it is a naturally occurring gas that permeates up from the inside of the planet, and is present in all mining operations, and is also present in natural gas that you pipe into your house, along with being present in almost all rock like granites.
One thing I can add is that a cut in the ocean is not that painful at all, as the sea water is at almost the same osmotic potential as your blood plasma, so does not trigger the pain reaction. however washing with sea water is not a good idea, not from the salt water itself ( sterile saline is a very good wound irrigator, and surgical saline is often used to clean wounds in the ER as it is both sterile and non irritating to the exposed wound) but from the contaminants in it, from heavy metals to pesticides to things like plankton and larval forms of many animals that can infect the wound itself.
Bricks are very individualistic of the supplier, mostly being either defined these days by a standard of some sort, as is the thing here in South africa, and generally the individual brick manufacturers ( here there is the major supplier, Corobrick, successor to the old Coronation Brick works, and another, Ideal Brick) make brick styles that are similar enough to work together in construction, or at least so that you can work one size to another with little effort. The actual size is more dictated by conventions, local builders likings and history ( a century old Coronation brick is remarkably similar in size to a Corobrick one, probably due in a lot of cases to still being made on the same machinery as well, and with the same presses and kiln designs as well) of the sizes they were comfortable with.
The actual size within limits is not too much of a concern, larger bricks and smaller bricks roughly use the same volumes of mortar, as most is in the lines of joins, and the vertical lines tend to even out the volume in the typical house build, as the larger bricks will probably have a thicker mortar line. Most of the cement in a house is used as plaster to make the walls smooth in any case, not in the actual courses, and in the foundations as well. Size is more with how many you can carry at a time, the smaller bricks more, the larger fewer, but the actual laid wall area will be the same per load, and the laying speed similar for both, though a smaller brick is faster to move as it needs less muscle strength to get it in position.
Bricks are always going to be picked up by hand multiple times during laying, so a lighter brick will mean less effort, even if it means more movements. All evens out with enough time and wall area in many cases. Smaller bricks allow more courses of wire reinforcement in a wall though, so it actually is safer and stronger, plus you get finer control of heights, as in most cases the penetrations in a wall, like door frames and window units, are designed for a particular brick spacing so they occupy whole numbers of bricks and you can easily place them during wall raising as you reach the lower parts, and then use half bricks every second row to get the overlap required in the construction, or in a double wall build get the tie between the separate wall units at the penetration you need, instead of having to use either wire ties or separate brick ties.
Even amongst different brick styles there are differences in most dimensions, but they tend to be within a range that is enough to use different families to build up a wall that will be plastered later, or to do things like move windows or doors at a later stage during renovation. you just end up with some thick mortar lines in places to get the fill.
A smaller brick is a brick that is cheaper to manufacture, as you have to fire it for a shorter time to vitrify the clay all the way through ( or at least deep enough into the clay to be usable), as well as having a better packing in the kiln used to fire them, along with less wasted brick after firing. Larger bricks require a much longer fire, as you have a fixed temperature in the kiln, and the brick is slow to vitrify, this is a fixed rate that it progresses into the surface, and the smaller brick has a larger surface to volume ratio.
As bricks tend ( at least these days ) to be delivered palletised, as opposed to the old way of bulk bricks being delivered in a tipper truck, they are fired shorter time, and are thus weaker, which is actually an advantage as there is built in crack stopping and expansion in the brick failing before the mortar joins, stopping any cracks from propagating all the way through the wall.
Century old bricks were fired almost to be fully glass, so they would survive handling, but they then are both very likely to be somewhat distorted, and also the mortar join will be the weak spot. Hard fired brick does have a use as high strength wall, but in a regular house this is not needed with the building code being designed around a massive safety factor on the much weaker brick allowed and the lowest allowed mortar strength. The standard double wall construction method with brick is much stronger than any load the house will ever experience.
Now, if you are building with hollow concrete block you have a much weaker wall, simply due to the block itself being a very weak item, and with not much surface area to act as a mortar joint between them as well, meaning that wall had a much lower load rating despite being a much larger block.
Windows search indexing can do this, simply in it's regular scanning to see any "changed" info in the file system. Annoying when it happens, and can be turned off, as it is only there to make any search in windows you make a few seconds faster, by making a cache of indexed keywords beforehand.