I’m just some guy who knows nothing. I love physics, sure, but I don’t actually understand any of it. I’m stuck in pop science. Late at night, thoughts about quantum worlds and extra-dimensional universes start crawling into my head and I can’t sleep. Sometimes I get this urge to go to the negative side of the Kelvin scale and pull off the impossible – like achieving negative volume or something.
Anyway. This evening I consumed some content on relativity. And every single time I think about it, it hits me the same way – if I increase my speed, time itself will start moving “slower” for me!!! Why does this happen? How does it happen? I was talking to Claude about it.
Let’s say I’m on a spaceship. I can see my friend back on Earth through the window. If I start moving really fast, I stay young. My friend gets old. If I keep observing my friend through the window, will I see a timelapse of my friend going from teenager to old age right in front of my eyes?
Claude’s answer was: If I’m moving away from my friend, every photon reflected off my friend will take longer to reach my eyes, because the distance between us keeps increasing (think about it… stars that are light-years away… even farther… you and I just keep drifting apart like that…). So the photon has to travel a longer distance to get to my eyes. Because of this, I will see him in slow-mo, and he won’t seem to age much in my eyes!! On the other hand, if I take the spaceship and head toward my friend, I’ll see a timelapse of my friend aging rapidly.
And in both cases, whatever I see when I look at my friend through the window – my friend sees the exact opposite when looking at me. (Assuming the telescope is aimed right!) So if I see my friend getting old, my friend will see me stuck in my teenage years for a long time. And vice versa.
Got it. That’s the twin paradox.
At this point in the conversation, something clicked.
Worldlines in Spacetime -- Graph 1
Friend at rest traces a vertical worldline; the traveller’s worldline tilts toward the light cone as velocity increases.
In this graph, if I take my friend as stationary, he traces a path parallel to the x-axis. And me, since I’m going fast, my slope is positive.
I couldn’t figure out which axis had which quantity. But something was forming in my head, I could feel it!!!
If I cut out a specific section of the graph (cutting in such a way that I’d need to run scissors parallel to the y-axis twice), the length of my path in that section is longer than my friend’s! (And vice versa – if I’m the stationary one, then my friend becomes the moving one, and then…)
If I treat the length of these cut-out paths as “how much we aged”, would that make any sense? I asked Claude.
His answer: “Yes! You’ve basically just invented spacetime diagrams (Minkowski diagrams) yourself. That’s exactly the right intuition.”
He also said my setup was mostly right. I did make a mistake though – I assumed “longer path = more aging”. In spacetime, a straight line actually represents the longest proper time! That went a bit over my head. I’m not exactly fluent in anything beyond Euclidean geometry.
If I take that 2D graph and make it 3D –
Hand-drawn 3D intuition sketch
An attempt at imagining the 2D spacetime intuition as a 3D projection.
I wrote all of this because I’m genuinely happy. Whether figuring out the idea of Minkowski diagrams on my own actually counts for anything, I don’t know. And there was still a flaw in my idea on top of that.
But maybe I’m on the right track. Maybe the right intuitions are showing up. “Maybe” being the key word here. There’s a long way to go!
Just thinking about it makes me really happy. I read somewhere that people like sharing their joy with others. I want to share mine with whoever’s reading this. So here we are.
Wrapping up for now.
It’s currently 3:43 AM.
‘Late Night Intuition’ May 26, 2026 2:53 AM