It was not too long ago that scientists spoke about space and time as two separate things. The contributions of Einstein in the first part of the last century changed that. Increasingly since then, space and time have been referred to by physicists as the ‘space-time continuum’.
Whereas space, prior to this, was considered to have three dimensions, Einstein’s contribution gave rise to a four-dimensional concept that included time1.
This continuum was likened by Einstein and later by others to a sheet of rubber that can expand and contract, curl or lie flat, affected by the displacement of matter in a way that science is still coming to understand.
The nature of space and time or ‘space-time’ is still in a stage of theoretical unfoldment, yet even now, almost a century after Einstein’s revolutionary presentation of the new theory, most people still have difficulty picturing physical reality as four-dimensional, and a five-dimensional reality seems even further away.
As an abstract concept, the ‘space-time continuum’ is more of a mathematical idea than an image – one that does not readily lend itself to easy contemplation, especially when we try to picture ourselves as living within it. For this reason, it is helpful to seek the support of metaphor as we try to do so.
Einstein‘s metaphor for space-time was the ‘rubber sheet’ mentioned above. In trying to locate ourselves within this metaphor, we either have to think of ourselves as part of the rubber sheet itself, or, we can expand the metaphor and think of the rubber sheet as having an inside and an outside with an empty space in between – a layer of space in which we live.