In a nutshell, Edelstein claims that when a ship travelling at near the speed of light comes into contact with free-floating Hydrogen atoms in space, the relative velocities of the ship and the Hydrogen would turn it into a lethal blast of radiation, killing the crew. Edelstein used the crew of the Starship Enterprise as an example saying "Well, they're all dead."
I'm not going to argue the physics with a physicist, but when he starts talking smack about Star Trek he's on my turf. There are several reasons why interstellar Hydrogen (and anything else that happens to be floating around in space) presents little to no threat to the crew of the Enterprise.
Reason 1: Navigation Deflector.
In the Star Trek universe, Starship designers have anticipated the problem of floating interstellar debris: be it asteroids, dust or molecular Hydrogen. As a solution, every Starship is fitted with a vital piece of equipment: the Navigational Deflector (also occasionally called the "Asteroid Beam"). Its function is to project a high particle-density stream of radiation out ahead of the ship so as to bump any small obstacles out of the way.
You'll recognise the Navigational Deflector as the large, glowing (usually) blue thingy in the front of the ship:
|Glowing Blue Thingy|
Larger obstacles present a challenge for the Navigational Deflector, and must be navigated around. Hydrogen is not a problem.
Reason 2: Bussard Collectors
Encountering Hydrogen in space is, for a Starship, actually a very good thing. Reason being that Starships are powered by Hydrogen. For this reason, Starship designers have equipped most Starships with devices called Bussard Collectors, or Ramscoops. The second name being more descriptive as to their function.
These are the glowing red (usually) thingies at the front end of each Warp nacelle:
|Glowing Red Thingy|
These devices project a strong magnetic field out ahead of the ship, capturing free-floating Hydrogen (having been ionised by the Navigational Deflector) and funneling it into a collector. From there it gets processed and eventually ends up in the ship's fuel tanks, ready to be annihilated with some antimatter.
Reason 3: Warp Drive
This is a tricky one. Although Warp Drive allows people in the Star Trek universe to travel at velocities far in excess of the speed of light, they're not really travelling faster than light. Because, well, that would be impossible.
Instead, the Warp Drive uses incredibly powerful artificial gravity and electromagnetic fields to curve (or warp) space-time, thus effectively reducing the distance between them and their destination. The ship then travels at nice, comfortable, sub-light speeds through the newly warped space. As soon as the ship has passed through a particular region of space, it snaps back to its normal dimensions.
You may have wondered why the image of the ship stretches out as we see it go to Warp... well, that's why. It's not really stretching, it's just travelling through a region of warped space-time.
|Not Really Stretching.|
Even if the Navigational Deflector and Bussard Collectors were to go offline, that free-floating Hydrogen wouldn't pose much of a threat to a ship travelling at an actual speed (relative to the space around it) of a few thousand kilometers per hour. Friction? Yes. Lethal blast of radiation? Hardly.
So don't worry. Despite inflammatory headlines on MSNBC, Captain Kirk and the gang are quite safe on the Bridge of the Enterprise. They have more to worry about from Klingons and Romulans than free-floating Hydrogen.
If you're interested in learning more about the physics and technology of the Star Trek universe, I recommend The Physics of Star Trek - Lawrence Krauss and Star Trek: Science Logs - Andre Bormanis.