Block 4 Part 2 complete

I've completed the study of Block 4 Part 2 (Road Transport). It was particularly interesting to read a little about how GPS works

It's beyond the scope of the T175 level 1 module, but it's also interesting (and somewhat bewildering) to note that GPS systems have to take into account effects predicted by the theories of special and general relativity - "time dilation" due to the relative motion of the satellites (they are not geostationary), and time compression due to closer proximity of Earth-bound clocks to a massive object (i.e., the Earth). The combined effect, according to this article published by the Ohio State University is that GPS satellites seem to gain about 38 microseconds per day compared with earth-bound clocks - and if the GPS system didn't account for this, it would have been hopelessly inaccurate within hours.

I don't have even a superficial understanding of special or general relativity (who does?) because every time I read about it, it makes no real sense - so I forget about it within minutes!