The 4th dimension is time
Essentially, any given dimension is the shadow of one above – a 3D object makes a 2D (plane) shadow
A 2D object makes a 1D (line) shadow
And a 1D object makes a 0D (point) shadow
Any given object of a particular number of dimensions is free to “move” inside its dimensions, but it cannot change the one of which it is a shadow
For example – you can move in 3 dimensions, but are bound by the 4th (from your perspective, time is unidirectional)
Likewise, a plane can move in 2 dimensions, but is bound by the 3rd (can only go left/right, up/down – not in/out)
If you could move freely in time, you would be at least a 5th-dimensional being – because your boundary would not be apparently-fixed time, but something else
July 31, 2020 at 08:40AM
via reddit https://www.reddit.com/r/explainlikeimfive/comments/i16q8l/eli5_how_does_the_4th_dimension_work/fzutt4u?utm_source=ifttt