Forbidden Planet

It was dark yesterday morning. Very dark. Unable to sleep, I was out of bed at 05:00 and, well, it is pretty dark at that time of the morning. I wasted some time on the computer and then headed upstairs to the kitchen at 07:00. Something was wrong. It should have been light outside, but it was not. I then realized they set the clocks back on Sunday. Only ... I didn't remember doing that and if the clocks had been set back an hour, the mornings would get brighter, not darker. Not only that, but I had taken my car for servicing the previous morning at 06:30 and it was reasonably light outside. I took a closer look outside and confirmed it was indeed night time dark. I double checked the clocks and they all agreed. The clouds were heavy and low and blocking out a substantial amount of light. I called Sofia in Montreal and she confirmed that it was very dark there as well. Even around 09:00, it was still a near dawn dark, though grey instead of red and gold. Image nabbed from here . It...

I heard there was a 40% chance of rain this morning and a 60% chance of rain this afternoon. Does this mean there is a 100% chance of rain some time today? Assuming rain in the morning and rain in the afternoon are completely independent events* (they are not). We calculate the probability of rain in the morning AND the afternoon to be 0.4 * 0.6 = 0.24 (or 24%). We calculate the probability of rain in the morning AND no rain in the afternoon to be 0.4 * 0.4 = 0.16 (or 16%). We calculate the probability of no rain in the morning AND rain in the afternoon to be 0.6 * 0.6 = 0.36 (or 36%) Adding up all the probabilities of some combination of rain and not rain we get 24% + 16% + 36% = 76% chance of rain today. Alternatively, it tends to be more commonly calculated as the (1 - probability of no rain**), which is 1.0 - 0.6 * 0.4 = 1.0 – 0.24 = 0.76 = 76% chance of rain. * Independent events are events whose outcome (result) has no relationship to previous outcomes (results). For example, to...