You know about length 'contraction': a moving object
is shortened by the fact of its movement, according to
SR, even though you can't tell it is really moving or
not if it isn't accelerating.

Inertial movement is obviously relative. I see something
moving wrt me, and I see you moving wrt me, so you may
or may not see the thing moving wrt you. You will unless
the object and you are moving at the same speed in the
same direction wrt me.

And what speed you see the object moving at determines
how much shorter the thing is while moving.

So, SR says every object has an infinite number of different
lengths all at the one time: one for every possible velocity
it can be seen moving at.

No mathematician would try solving a set of simultaneous
equations including: v=40; v=-20; v=10000000, but SR implies
a universe in which an infinite number of such equations
will work fine.

So, how to get around such absurdities?

Why it's simple. Just claim the effects are only observations,
not real effects.

People do this right here on the Internet in these newsgroups.

The title of this section is:

The "lasting effects of no effect" absurdity.

Let's list some of the supposed, lasting consequences
of the non-real effects:

A travelling twin comes back younger than his stay at
home brother.

A muon coming to earth from space lasts longer than
one in the laboratory.