Critiquing "writing"

So in the course of my life, I have the opportunity to critique other people's stories. Some are great, good characters, interesting plot, well-written dialog.

Then there are...the others.

Let me start off by clarifying that I don't claim to be an awesome writer (decent, maybe). However, if I write about a subject, I do at least basic research into the subject, and claim at least some proficiency. In other words, if you're going to write a science fiction story, know at least your basic science.

The following examples are all from one story sort of based around an artificial star that a ship is launching.

"[The artificial star] would heat up to more then ten thousand degrees Fahrenheit. It would then accelerate, moving away from the ship at ten kilometers a second."

1. That's the temperature of our sun (well, the sun's actually 11,000 degrees F, close enough). Wouldn't it be smart to move it away from your spaceship BEFORE it heated up?

2. You speak of acceleration, then give us a velocity. Minor detail, but again, it's a science fiction story. Your audience will expect accuracy.

"[The artificial star] pulled in mass from the area around it"

I'm guessing he wants to use "matter" instead of "mass." In other words, it would gain mass by collecting matter. Again, it's a science fiction story--keep your science-y words accurate. And where is this matter coming from? It's space...matter is in short supply. Fortunately, near the end of the story, he thinks to mention that there's a nearby asteroid belt. Oh, great, matter to collect! But...how is the star attracting this matter before it has mass? No mass, no gravitational pull. Sort of a chicken and egg dilemma.

"[The artificial star] pulled in mass from the area around it, becoming it's own gravitational singularity"

We'll ignore the "it's," since we're critiquing the science. In this case, I'm assuming he just heard the phrase "gravitational singularity," thought it sounded cool, didn't know exactly what it meant, and decided to put it in anyway. I won't claim any expert astrophysics knowledge...but I do know how to use Wikipedia. Among other definitions, a "gravitational singularity" is a black hole, or at least the center of one. Since the whole point of this star was to send light back to Earth to communicate a message, a black hole would kind of defeat the purpose. (Or maybe not, it would still send back "light," just not on any human-visible wavelengths, but I don't think that's what he had in mind.)

Later, an alien satellite cuts their ship in half with a laser beam! A few more issues crop up.

"Suddenly a beam of light cut through space, streaming past them. It began to sweep around, looking a bit like the beam of a flashlight searching through the darkness"

Think of a night, where there's no smog or dust in the air, but there's a low cloud cover. Now shine the light on the clouds. You can see the light on the clouds, if you look directly at the spotlight bulb you can see the light there as well...but you can't see the beam itself.

Why not? You need photons from the light hitting your eyes to see it. And if there's nothing in the air (or nothing in the deep of space) to scatter/reflect those photons, they aren't going to reach your eyes. I'm not positive, since a laser might carry particles of whatever created it along, but I don't think you can see a laser beam "sweeping" through space. That's why when you see them at laser shows, they put fog into the air first.

I could go on about what it takes for a laser to "instantaneously" cut through a spaceship, and how you wouldn't see tendrils of melted metal at the edges because they didn't have time to heat up and space is very cold anyway, and how you better have a heck of a good computer to calculate the trajectory to shoot an artificial star from your "tumbling" half-a-spaceship at a moving alien satellite, and how it wouldn't matter anyway because the alien satellite would just move...but it's late and Child's gone to bed.

Now, with all that said, I can take as well as give. If any notices mistakes in what I've said, or wishes to clarify or outright contradict what I've said, then go right ahead. Like I said, I'm not a physicist, astro or otherwise, so everything I said was simply "from my understanding" and a little from Wikipedia. I'd be more than happy to be clarified on any points.