The far-left star in Orion’s belt, which Kirk cites as the home of a future author, is Alnitak, also known as Zeta Orionis.
There’s some disagreement about how far away from us this star is, but it’s somewhere in the region 1000 light years. That’s a year away at warp 10, although as we’ve already learned, distance is pretty flexible in Star Trek.
The star we call Alnitak is really a system of at least three stars. The main one is a blue supergiant somewhere between 14 and 30 times the mass of our Sun (depending on how far away it really is), and it has a companion of about half that mass orbiting pretty closely, at about the orbit of Saturn. There’s then a third star - around the same size as the smaller one in the main double system - orbiting about 75 times further away.
Because these stars are so hot (more massive stars = hotter), the habitable zone is pretty far away - around 300 times further from the main star than Earth is from the Sun, or 10 times further out than Neptune. We don’t currently know of any planets in this system, but if one exists it hasn’t had much time to cool down, let alone evolve life: the larger and hotter a star is, the shorter its life, and these stars are only around 7 million years old. For comparison, we think it took around a billion years for life to arise on Earth, so we wouldn’t expect to see anything in this system. So this author wouldn’t be a species that originated on that planet, but maybe there’s a colony there on a still-cooling planet, for… reasons? Maybe his parents study planet formation and he grew up in a scientific research outpost? I’m going with that.
Edith Keeler drops a massive hint early in City on the Edge of Forever that she’s going to turn out to be important to the future by being able to predict it.
She starts by saying that “soon, man is going to be able to harness incredible energies, maybe even the atom.” This is pretty prescient for 1930, considering the neutron would not be discovered until 1932 and the first nuclear fission reaction (splitting the atom) would not occur until 1934.
The basic theory behind extracting energy from the atom was already in existence, though; it comes from Einstein’s famous equation E = mc2, published in 1905, which states that mass and energy are equivalent. The mass, m, in an atom is tiny, but the speed of light, c, is large, so you get a lot of energy from a small amount of mass.
Keeler goes on to say that this nuclear power will one day be used in spaceships. There have indeed been nuclear powered space missions, including Voyager andNew Horizons, which were heading too far from the Sun to get sufficient power from solar panels. And if we’re ever to manage interstellar travel, nuclear fusion is one of the suggestions of how that might be done.
Her further predictions that nuclear power will be used to find ways to feed the hungry and cure diseases have also, alas, not come to pass.
Incidentally, the world’s first nuclear powered aircraft carrier was launched in 1960, just a few years before this episode was written. It was called the USS Enterprise.
City on the Edge of Forever opens with the Enterprise in orbit around something that’s setting off the fireworks in the navigation console in front of poor Sulu. Spock is unperturbed, though, because he’s chasing Science: specifically, something he calls “ripples in time.”
Now, obviously, we know these time ripples are caused by the Guardian of Forever. But it’s pretty cool that we’ve actually observed an effect like this recently from Earth: we call them ‘gravitational waves’.
Gravitational waves are a consequence of Einstein’s theory of General Relativity, which says that massive objects (by which I mean anything that has mass) distort the space around them. When dense objects like neutron stars or black holes orbit each other, these distortions radiate outwards as gravitational waves, which are essentially ripples in spacetime. Although Einstein suggested this around a hundred years ago, they were only detected for the first time by LIGO in September 2015.
When the gravitational field changes, so does the speed of time. So technically, your head - which is further from the Earth’s center of gravity - is aging faster than your feet (although the difference is tiny - something like a few billionths of a second over an average lifespan). Hence, those gravitational waves also contained “ripples in time,” albeit very, very tiny ones, because they came from far away.
So ripples in time are real! Does that mean the LIGO detection was not a pair of merging black holes as has been assumed, but actually the Guardian of Forever? I vote yes.
