Proof
that an orbit around a massive body takes the shape of a conic section.
This is a bit dry, I'm afraid, and is unrelated to relativity,
but none the less I found it really cool to finally work out the
details of this one. | Newtonian Orbit Shapes |

Might it be possible to use quantum
entanglement
to communicate faster than light? This frivolous little tale
considers one possible consequence. | The CCentipede |

No relativity website is complete without a
derivation of the Lorentz transforms! So, here's mine. | Lorentz Transforms |

The Twins, moving linearly,
neglecting acceleration. This is the classic special
relativity
"paradox". What makes my treatment different from the 500
other
discussions you can find on the web or in textbooks? I don't
compute gamma, I don't use a Lorentz transform anywhere in it. | The Linear Twins |

The Twins, moving linearly ... *not*
neglecting acceleration. The traveler accelerates at 1g for the first
half of the trip and decelerates at 1g for the second half of the
trip. Treated from Earth's PoV, from the MCRF of the traveler,
and from the porthole view. I don't know how educational this
one
is but it's certainly entertaining. What hair! | The Accelerating Twins |

What
does an astronaut see, looking through a
telescope at a distance planet, when a spaceship first starts to
accelerate toward that planet? Not what I expected, that's
for
sure. | Porthole
View, Looking Forward |

An orbiting clock,
neglecting
gravitational effects (i.e., a clock moving in a circle).
Everybody knows this one, so what's the point? Well, I do it
from
the clock's point of view, too. | The Revolving Clock |

The Twins again, but now they're going in
circles: Counter-orbiting space ships. Each time
they pass
each other, A observes B's clock is running slow, yet somehow it never
really falls behind. So, it must catch up again. *But
when?* | The Revolving Twins |

When time runs *backwards:
*A
spaceship orbits around a distant planet. How fast is time
passing on Earth, as viewed from the MCRF
of the spaceship? The
answer is strange, indeed! | The
Revolving Astronaut |

The Sagnac effect is often claimed to be
difficult to explain, requiring very messy mathematics.
Sometimes
it's said to admit no explanation with special relativity.
Actually it's a rather simple effect, and no math more advanced than a
Lorentz transform is needed. | The
Sagnac Effect |

It's well known that the gas around some
supernovas appears to be moving away from the star faster than **C**.
It's just a trick of the light, but working out the details is a little
messy. | Superluminal Shells |

Space is weird just outside the event horizon
of
a black hole. In Schwarzschild coordinates things seem to
"stick"
just before they get to the horizon. This is a somewhat naive
discussion of that behavior. | Sticky Black Holes |

A few items having to do with magnetism, including derivation of the field of a dipole. | Magnetism |