Hi
I’ve been studying pharmacy/medical sciences for all my adult life when i stumbled upon “a brief history of time” by stephen hawking
Anyway,for a person who hasn’t studied physics much..how does “spacetime” exist? I mean einstein abandoned the idea of absolute time
But what is spacetime? And how does time exist as a physical dimension? I mean it’s just something we measure as it passes
How does all this exist?
In: 3
Time is “just something we measure as it passes” in the same way that distance is “just something that we measure as we pass it”.
If you want to uniquely identify an event in the universe you need to say where it happened (space) and when it happened (time). You need four values…three spatial dimensions and one time. Without all of that, you can’t tell if two events are the same thing (same time and position) or different things (same time/different positions or same position/different times). Our universe is four-dimensional in the sense that you need (at least) four unique values to specify a unique event.
It turns out that a *lot* of physics gets a lot cleaner, including some things we observe experimentally but couldn’t explain before, if you treat the universe as a four dimensional thing where three dimensions are space-like (we can move freely in either direction along them) and one as time-like (we can only move in one direction along it).
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