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Within relativity (both special and general), changes of reference frames can change both the notions of space and of time, with one depending on the other as well. As a consequence, it is necessary to treat both concepts in a unified manner. Hence the term spacetime.
2
votes
Derivation of SR formula involving an absolute interval
The spacetime diagrams below might be helpful. …
10
votes
Accepted
Meaning of simultaneity in special relativity
UPDATE (to address the comment by the OP):
A spacetime diagram is useful to clarify the ideas. … Using my "spacetime diagrammer" https://www.desmos.com/calculator/dha8izuxz1 ,
with event $P(x,t)=(0.5,1)$,
Alice (in RED) says that distant event P is simultaneous with tick-1 on her clock... …
1
vote
Intuition as to why a constant four-acceleration must be zero
I'll add vector-signs and hat-signs, but I'll only work in (1+1)-Minkowski spacetime with $(+,-)$-signature.
Can you quote the source (the "tutorial")?
Maybe I am misunderstanding the situation. …
3
votes
Why do we need Minkowski spacetime in special relativity?
So, one important value of the structure of Minkowski spacetime is that it can be used in more general situations than it was initially conceived for. …
2
votes
Accepted
How can it be that Doppler Factor $k=\frac{1}{k}$?
Eq.10 is incorrect.
Observe that:
$$\frac{cT_2}{cT'}=\frac{(1+\beta)cT}{cT'}=\frac{1}{k}\tag{10}$$
implies
$$
\begin{align}
cT
&=\frac{1}{(1+\beta)k}cT'\\
&=\frac{1}{(1+\beta)\sqrt{\frac{1+\beta}{1-\b …
3
votes
Accepted
Minkowski diagram of two frames in rest with respect to each other
Here is a spacetime diagram [drawn on rotated graph paper]
of the back of the stick
showing two reference frames,
one for the back of the stick (through the origin event),
and the other for the front … On a spacetime diagram drawn by another inertial observer who meets [the back of the stick at] event O
and travels with velocity (-3/5)c with respect to the stick, the stick-ends' frames appear as shown …
1
vote
Can space proper-time (SPT) diagrams as used by Lewis Epstein in Relativity Visualized be us...
(update2: So, it seems the length of path in a SPT-diagram
is equal to the spacetime-interval between the endpoint-events
(i.e. the proper-time for the inertial astronaut experiencing the endpoint-events … By constast,
here's my variation of the standard Minkowski spacetime diagram:
https://physics.stackexchange.com/a/507592/148184 (go to the "Clock Effect" section halfway in)
as my answer to What is the …
1
vote
Is the space-part of a four-vector temporally connected to the time-part and vice-versa?
Can we say that it's the time part that's involved in defining the space part and the space part in defining the time part?
A displacement 4-vector has
a time-component that has nothing to do with …
2
votes
Radius Four-Vector in Minkowski Spacetime
You seem to be confusing (or improperly comparing)
the spacetime-displacement 4-vector of an event that is represented in a different frame by an equal-Minkowski-magnitude 4-vector with different spacetime-components … (addendum: These unequal-Euclidean-magnitude spatial-displacement vectors are the spatial-components of
the equal-temporal-Galilean-magnitude spacetime-displacement 4-vectors related by a Galilean-boost …
1
vote
Confusion regarding common definition of proper time?
For that worldline, all observers agree on the readings of the clock on that worldline. )
The Spacetime [square-]interval is like the squared-distance between two points in the plane (taken along a straight … In Minkowski spacetime, the square-interval from chronologically related events A to B is the square of the proper time along the inertial worldline from A to B. …
0
votes
Special Relativity Assumption
For completeness [especially for those without easy access to the reference], it might be good to include the other assumptions.
Each admissible observer presides over a 3-dimensional, right-handed, …
0
votes
Schutz and spacetime diagrams
Note that Galilean physics is all you need to answer this question. If you draw the position-vs-time graph of a plane moving with velocity v, you have a line with slope v. If you reorient the axes so …
1
vote
Hypersurface vs Hyperplane
Yes. A hypersphere is a hypersurface that is not a hyperplane. Hyperspheres and hyperplanes are examples of hypersurfaces.
It's akin to a sphere and a plane being hypersurfaces in three dimensions.
0
votes
Is it possible to derive the time dilation expression directly from the space-time interval?
Write $\Delta s_{OQ}^2=\Delta t_{OQ}^2-\Delta x_{OQ}^2$,
where we interpret the spacetime-displacement $\Delta s_{OQ}$
and $\Delta t_{OQ}$ is the adjacent side and $\Delta x_{OQ}$ is the opposite side. …
2
votes
What are some of the uses of the invariant spacetime interval?
In special relativity, one uses a spacetime diagram, with the underlying Minkowski metric. … The time dilation problem is essentially relating
"the spacetime interval (the elapsed proper time) along a straight worldline segment from event A to event B"
with
"the temporal-component of the spacetime-displacement …