Not really a recent thing, but the idea that supposedly if you travel faster than light, then you begin going back in time. But that doesn't make sense to me. I guess the math has to work out somehow, but it seems to me that if light has a speed, then - ignoring the logistical issues related to having the power to travel ftl - travelling faster than light would simply be that, faster than light. Or to put it another way, if it takes 8 minutes for light from the sun to reach earth, then an object travelling 2c should take 4 minutes to travel the same distance, not negative 4 minutes or however that'd work out.

The only conclusion I can come to regarding how that works out logically, is that relativity sets the time light travels to "0" regardless of time taken, because that's the only way I could see a negative value making logical sense. However it seems like that'd have its own issues, plus it implies that light instantly reaches its destination. Yet we know light has a speed and takes time to get places. It just... doesn't make any logical sense. Yet I guess the math must work out otherwise scientists would have blown so many holes in relativity that it wouldn't be used anymore.

inb4 "but causality..."

The speed of causality is inferred from the speed of light and the speed at which fields propagate in a vacuum. Causality, or the idea that cause must be observable before effect, is a human concept. Observing effect before cause doesn't break causality, it only appears to do so because we're seemingly limited to the speed of light. The reason why causality is said to have a speed (the speed of light in a vacuum) is because, with the exception of quantum tunneling, we've never observed anything that moves faster than light, so it's a seemingly safe assumption to say that cause and effect play out at a speed no greater than light in a vacuum. Or to put it another way, the speed of light dictates causality, not the other way around. If something is found to be faster than light (like particles tunneling through objects), then causality must shift with it.

Adding a bunch of quarters together gets a third.

Admittedly a bit of an oversimplification. It's from a YT video: a chocolate bar costs £1 but four wrappers gets you a free bar. How many bars can you get for £1000?

So you buy 1000 bars which gets you 1000 wrappers. Turn those in for 250 bars. With those (actually 248) you get 62 bars. Add the 2 from before and turn in 64 wrappers for 16 bars. And again for 4, then 1. It's a sequence of quarters and the solution is 1,333.