Doctor Who - The Impossible Planet. Science Quibble.

[fangrrl_squees]

As I came home in a strangely foul mood, I decided to break out the big guns: fattening food, a bottle of wine, and my brand-spanking-new Doctor Who DVDs. Naturally, given my horrible mood, I found something to grumble at.

So, I'll admit that my grasp on science ain't the best. Nor do I usually expect anything resembling reliable science in my sci-fi but...

If the black hole of "The Impossible Planet" is tearing all sorts of shit apart

(hold on, the really fab scary bit is on. Poor Toby.)

Anyways, as I was saying. If the black hole is apparently *still* hauling in new material and has apparently been on the spot marked X for zillions of years, either it's got an event horizon the size of, oh, about 90% of the 'verse, or said event horizon is expanding. Lots.

WTF?

I don't know much about black holes, but that one in TIP/TSP just ain't working for me. And would it have killed them to suggest a blueshift as all that energy is accelerating into the black hole?

Okay, so maybe I've read a bit more about black holes than I really need to.

Definitely a hint of a Firefly-influence in the soundtrack when the Scarlet System falls into the black hole. *Sighs happily and reaches for the wineglass*

And, on another note entirely, I've just DL'd the LJ talk thingummy and I'm online as fangrrl_squees

Comments

[astrogirl2.livejournal.com]

What really gets me is all the marvelling at how incredibly impossible it is that they're in orbit around a black hole when, um, it's perfectly possible. That and the dead body floating off the planetoid, apparently because it was being "sucked in" by the hole... Black holes are not magical vacuum cleaners! They have gravity that works the same as everything else's gravity, it's just really really huge, if you get close enough. What was really impossible about that planet is that they could live on it without being horribly fried by x-rays from all that crap falling into the hole.

Really, I loved that episode, but I sometimes think that I shouldn't be allowed to watch SF shows that deal with things like black holes. Stupid astrophysics degree... :)

[fangrrl-squees.livejournal.com]

I wasn't going to mention the x-rays, lest I be accused of being *too* picky, but I'm with you. :)

[bovil.livejournal.com]

So maybe I was connecting too many lines, but I took it more not that it was impossible to orbit a black hole, but that the planet should not have been able to maintain the orbit it was maintaining. After all, the research vessel didn't have enough thrust to escape the gravity of the black hole unless it traveled up the "gravity funnel..."

...but we're talking gravity modification. The central premise was there was something countering gravity (something that wasn't a simple application of thrust) allowing the planet to maintain orbit, so by modern physics we're in fantasy land anyway. Whatever was allowing the planet to maintain the impossible orbit I suppose could have also deflected the outbound x-rays around the gravity funnel.

[astrogirl2.livejournal.com]

Yeah, you can explain it that way, and I think you kind of have to to get it to make any kind of sense at all, but there's nothing in the dialog to indicate that, and it seems a little bit of a reach to me that even the Doctor could figure out that they were, say, inside the Roche limit by one glance out the window. And all of the other characters act like it's obvious, too.

Plus, on the "Confidential" for that episode, RTD said that someone told him after they'd shot the episode that it was possible to orbit a black hole, and he was all, "Who knew?" So it really was a genuine mistake.

orbiting a black hole

[(Anonymous)]

Of course it's possible to orbit a black hole. Take the Sun and the Earth - we don't go plummeting into the sun because we're orbiting it.

However... with a collapsed star above ~ 1.4 solar masses space-time is well, massively warped. So, basically as long as you "keep your distance" you're ok.

I personally don't like it when they show material getting "sucked in" to the black hole. Due to the distortions of time it wouldn't be seen that way to an observer, but perhaps I'm nitpicking sci-fi again!

Regarding the persons earlier point about the X-rays - a) it would depend on the amount of matter in the accretion disk or to put it in sci-fi terms "being sucked into the black hole) and b) black holes produce jets.

However so far, we've been unable to conclusively either a) observe a black hole or b) do experiments on one.

It's all just theory (still) which makes it ripe for sci-fi. However the audience now is better educated than it once was in science matters which means that dramatic licence can only take you so far.

Re: orbiting a black hole

[astrogirl2.livejournal.com]

Of course it's possible to orbit a black hole.

I know that. You know that. Russell T. Davies apparently did not know that. :)

- a) it would depend on the amount of matter in the accretion disk

Which, in the episode, was shown to be -- in technical terms -- one whopping hell of a lot of stuff. :)

However so far, we've been unable to conclusively either a) observe a black hole

There's some very good observational evidence for them, though. As theories go, it's a pretty well-supported one.

Re: orbiting a black hole

[fangrrl-squees.livejournal.com]

Which, in the episode, was shown to be -- in technical terms -- one whopping hell of a lot of stuff. :)

I love it when you guys get techie on me.