|Space-time, philosophy: space time is a three-dimensional space with time as a fourth dimension. The fact that time is interpreted as a dimension distinguishes the space-time from multi-dimensional mathematical spaces, in which time plays no role and which are therefore structured differently. In particular, the space-time has no measure which can equally be used for spatial distances as well as for time measurements. See also relativity theory, four-dimensionalism, world lines.|
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Space-Time/Relativity Theory/Feynman: One could say that a given "depth" is a "mixture" of all depths and widths.
If it were impossible for us to ever move, we would always see the "true" width.
Could we not consider the Lorentz transformation in the same way? We also have a mix of positions and time here.
A difference between a room measurement and a time measurement produces a new room measurement.
In other words: time is mixed into the measurement of a man's space as observed by the other.
Ontology/Feynman: The "reality" of an object is a little bigger (roughly and intuitively spoken) than its "width" and "depth", because they depend on how we look at it.
Relativity theory: our brain has never had any experiences with speed close to c so that we could not integrate any experience, of the type that time and space are of the same kind.
It is as if we could always stand in a position and not turn in the other direction. If we could, we would see a little of the other man's time. We would "look back" a little.
Space-Time/Feynman: In a world where space and time are "mixed" (this is actually our world, seen close to speed of light), objects are more like a kind of "blob", viewed from different perspectives when we move at different speeds.
Def Event/Feynman: a point (x, y, z, t) in space-time.
Even light, since it moves, would be represented as a curved line.
It should be expected that a new, rotated pair of axes would have to be used here. (?).
But this is false because Eq. (17.1) is in fact not exactly the same mathematical transformation as Eq. (17.2). (Difference of signs, sin and cos are not exact equations of the algebraic expressions).
Nevertheless, both expressions are very similar.
Geometry/Relativity Theory/Feynman: Because of this change in sign, it is not possible to imagine space-time as a real, normal geometry.
Coordinate system: a moving man must use a new set of axes which are evenly inclined to the light beam. ((s) The right angle of the axes is reduced).
Vom Wesen physikalischer Gesetze München 1993
Vorlesungen über Physik I München 2001