Relativity

Into the cosmos Roemer gazes,
watching distant planets
making note of different phases,
identifying patterns 
in the celestial movements.

What of the 
eclipsing moons of Jupiter--
unevenly spaced,
a delayed event,
based on our position and their place.

He purposes 
a new hypothesis:
suggesting a finite speed.
That light must travel
between objects,
albeit very quickly.
186,000 miles a second, in fact
but not instantaneous C. 

And to prove that,
Maxwell unifies partial theories 
determining the propagation of light--
electric and magnetic, 
charges and currents.
Fields exerting force
upon those around it.
A sea of perfectly distributed 

peaks and valleys.
Crests and troughs, 

naturally occurring
with different lengths.

Electromagnetism emerges.
Like ripples in a pond 
from the epicenter,
waves all rolling outward
at fixed speeds--
at times visible,
others too small or too large to see.

It is reconciled 
that they must be
transmitting through the ether,
a medium, filling
an otherwise void
and vacuumed space,
for light to be measured--
not relative to a fixed position,
or recording a different pace.

Michelson and Morley come along
confirming with practical experiment
the speed at which light travels
remains consistent. 

As the Earth revolves around the Sun
no matter where in orbit 
the light is measured from,
the ether has no impact

on the final outcome.

Einstein and Poincaré argue
against ether's existence, and
from differing perspectives,
make a disagreeing agreement.
It is unnecessary and irrelevant, but--
was it resolved by physics or 
a mathematical achievement?

Einstein presses forward 

with relativity,
insisting the laws of science 

apply seamlessly
for all observers, and
no matter their own direction, or pace, 
the speed of light
moves at an unchanged rate.
 
A counterintuitive prophecy,
asking us to suspend
our then-held belief.
Time was not absolute, 
nor would it agree
when one observes light
from a different location from me.

He declares explicitly-- 
time and space are dependent,
intertwined fundamentally. 
And what an odd
and difficult conclusion,
indeed!

Consequently, our coordinates
increase to four from three,
and we discover: 
Energy equals Mass 
times the square of Light Speed. 
That the more energy
an object collects kinetically,
the greater its momentum is resisted,
proportionally.

And for a mass to reach
the speed of light
one would require infinite energy-- 
an edge to our own ability!

But this is just Special Relativity,
blending Newtonian,
and Maxwellian theories. 
Leaving a massive hole
in the thought experiment:
what if the sun were to vanish instantly?

Would Earth be cast from orbit,
freed from its gravity?
Or, would it take eight minutes
for its light, and pull,
to disappear completely?

It is here we reach 
the cusp of descent
into even greater matters 
and mysteries,
where space and time curve
around masses, 
in General Relativity.