For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.

  • Time relativity always boggles my brain, I accept the fact but I find crazy that if I strap my twin and his atomic clock to a rocket and send them out to the stratosphere at the speed of light, when they return he’ll be younger than me and his clock will be running behind mine. Crazy

    • It’s even crazier because you don’t need to reach the speed of light. It’ll happen in a smaller degree for any speed. Even in mundane conditions.

      For example, if your twin spent four days in a 300km/h bullet train, for you it would be four days plus a second.

      Usually this difference is negligible, but for satellites (that run at rather high speeds, for a lot of time, and require precision), if you don’t take time dilation into account they misbehave.

      (For anyone wanting to mess with the maths, the formula is Δt’ = Δt / √[1 - v²/c²]. Δt = variation of time for the observer (you), Δt’ = variation of time for the moving entity (your twin), v = the moving entity’s speed, c = speed of light. Just make sure that “v” and “c” use the same units.)

        • Without Einstein, I think that the discovery of time dilation would be delayed by only a few years. There were a lot of people working in theoretical physics already back then; someone else would inevitably dig through Lorentz’ and Poincaré’s papers, connect the dots, and say “waitaminute time might be relative”. From that, time dilation is a consequence.

          In special I wouldn’t doubt that Max Planck would discover it.

          I’m saying that because, in both science and engineering, often you see almost concurrent discoveries or developments of the same thing, because the “spirit of a time” makes people look at that aspect of reality or that challenge and work with it. The discovery of helium and the development of aeroplanes are examples of that.

        • IIRC the orbit of Mercure doesn’t work with Newton Model, and astronomers were predicted the discovery of Vulcain a small planet between Mercure and the Sun. So a new model had to be invented since Vulcain couldn’t be found.

      • Yes I knew about that and I’m glad that doesn’t make it crazier for me, instead it makes it easier to accept. If it were something that happened only after hitting some arbitrary speed value I’d be a lot more mentally damaged

    • The part that I understand in the intellectual sense, because I know or at least used to know how it follows from the math, but which just doesn’t feel like it should be the case, is the whole “relativity of simultaneity” aspect of it. That there isn’t an objectively true order in which events happen in, if the events in question aren’t linked by cause and effect. That is to say, it is possible for one person to see an event A happen before another event B, a second person to see the two happen at exactly the same time, and a third to see event B happen first and then event A, and for all three of them to be equally right. It just feels like, on some level, there ought to be one objectively true order to time, a single valid timeline that all events can be placed in relative to eachother, and for time not to work that way feels so absurd as to not even be able to articulate why the idea feels wrong.

    • From what I understand, you are always travelling at the speed of light through space/time, but when you move at high speeds through space that shifts the proportion of your speed out of the time dimension. And a photon travels only through space, experiencing no time between the time it was emitted and the time it was absorbed. What I just can’t wrap my head around is the concept of travelling at some speed without involving the time dimension at all.