General Relativity for Laypeople – A First Primer

'What Is World Line' illustration diagram was cited in Markus Hanke's blog in 2016.

The What Is World Line illustration diagram was cited in Markus Hanke's blog in 2016.

```Subject: General Relativity for Laypeople – A First Primer
Date: Apr 10, 2016
Author: Markus Hanke
Source: http://www.markushanke.net
/general-relativity-for-laypeople-a-first-primer/

what GR is about, without getting lost in mathematics, but also
without succumbing to the “easy way out”, as given by seemingly
simple yet highly misleading visualisations such as the ever so
popular “rubber sheet analogy”. It is to be understood as a plain
the interested lay audience with little or no mathematical
background, so I will sacrifice mathematical rigour for clarity and
understanding; the mathematical side of GR will be presented in a
future article. While the finer details of GR are undeniably hard,
its basic principles are simple, and can be understood by anyone.

Let us first of all recall a few important points from our
discussion of Special Relativity – if you haven’t read the articles
linked to above, I would urge you now to do so:

1.An event is a point in space at an instant in time

2.Space-time is the collection of all events

3.The geometry of space-time is the relationship between events,
i.e. of the relationship between measurements of time and space
taken at different places and times

4.In the absence of gravity, space-time is flat, and is described by
the laws of Special Relativity

5.Time and space have no universal meaning, they are
observer-dependent concepts

...

References :
[1] https://www.herongyang.com/Physics/Spacetime-World-Line-Sun-Earth.jpg
[2] http://pitt.edu/~jdnorton/teaching/HPS_0410/chapters/general_relativity/
...
```