Re: Vanishing ActHi Guys,
Lincoln, I Loved your course, "
The Theory of Everything" and apparently so did many others. A score of 4.7 out of 5 (on 61 reviews) is quite good at The Great Courses. As expected, it was particularly strong on particle theory. I look forward to viewing it again soon.
I'm no fan of ether but those who seek the simplicity of a
Euclidean perspective can easily be accommodated. Minkowski spacetime is considered
hyperbolic, as indicated by the
minus sign in the interval equation (e.g.
d² = r² – t², where
d is an interval,
r is a spatial span [or "radius"],
t is elapsed time and universal speed limit
c = 1 is implicit). The existence of a speed limit implies that space and time are not truly
independent coordinates since, by its own definition, translation through space can not occur
independent of translation through time.
Rearranging the equation however (to
r² = d² + t²), eliminates the minus sign and suggests interval-time coordinates as a Euclidean alternative. I'm not abandoning Minkowski spacetime, merely adding interval-time coordinates for their invaluable perspective. Physics is replete with coordinate systems, each advantageous in a particular situation.
Interval-time coordinates are the
only ones which correctly depict a lightlike interval. By contrast, Minkowski spacetime grossly misrepresents this so badly, that most physicists still exhibit
no grasp of the concept. For example, referring to a lightcone diagram in Minkowski spacetime coordinates, Feynman calls this interval a "separation", when that is anything but the case.
"
Where light goes from a given point is always separated from it by a zero interval,…"
p 99Here's what Rindler says:
"
Minkowski space…Such maps necessarily distort metric relations and one has to learn to compensate for this distortion."
p 90And here's what he means:
Pole Vault: A lightlike interval in a Minkowski diagram and the pole on a flat map similarly distort their actual extents. While the equator is 24,000 miles long, neither the south pole nor a lightlike interval have any length at all, contrary to these common representations.Interval-time coordinates are refreshingly consistent with Taylor & Wheeler's correct expression:
"
…the interval AB between two events can vanish even when the separations Δx, Δy, Δz in space and Δt in time between B and A are individually quite large."
pp 37, 38
Closing In on Reality: Interval-time reveals that, as spatial and temporal separation become equal (regardless of size), interval separation disappears.