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I was watching the Star Trek reboot again last night, and the scene where the red matter was injected into the centre of Vulcan got me thinking.

Clearly this was having major catastrophic effects as it was pulling the whole planet Vulcan towards it. However, while rocks were falling (and the odd statue), and cracks forming in the crust, the gravity for those on the surface seemed unaffected.

Given that a singularity had been placed at the centre of Vulcan, and the extreme gravity that it would entail (it did suck the whole planet in), why weren't the inhabitants of Vulcan pinned helpless to the surface, especially near where the hole was drilled? (In universe answers only please!)

Below is the disaster unfolding:

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    Because gravity is inversely proportional to the square of the distance, so the red matter was able to collapse the core of the planet, which in turn sucked the rest of the planet. Commented Jan 18, 2017 at 9:16
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    @Gallifreian - I’m not sure that would explain it. The strength of the gravitational force exerted by an object does indeed depend on the inverse square of its distance, but if the micro black hole created by the red matter wasn’t increasing the gravity on the surface, its mass simply couldn’t have been significant relative to Vulcan. And I can’t imagine that its higher density would influence its gravitational effects overmuch (gravity of a spherical black hole, or the Earth itself, acts as if from a point source at the COM).
    – Adamant
    Commented Jan 18, 2017 at 9:20
  • But given the sheer amount of gravity was sufficient to pull apart rock, the surface of the planet couldn't be so far away as to remain completely unaffected by the large gravity at its centre. There seems to be no impact on their ability to move on the planet's surface.
    – Jane S
    Commented Jan 18, 2017 at 9:20
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    Excuse me, but did you want to say Zachary Quinto and Anton Yelchin? Must be autocorrect... Commented Jan 18, 2017 at 9:46
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    Yep, Benedict was the only reason I watched ST:ID. Too bad this scene didn't make to the final cut though. Commented Jan 18, 2017 at 9:50

1 Answer 1

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Surprisingly, a singularity the size of the droplet of red matter seen in the movie would hardly effect the surface gravity of Vulcan (that is, until it collapsed).

According to this answer on the Physics SE, a stellar black hole can be roughly calculated as being 6 * 10^18 kg/m^3. (As an aside, can we seriously get LaTeX enabled here?). The droplet of red matter we see in the movie is likely somewhere around 0.05 mL (based on a "standard" drop according to pharmacists). Putting this all together, we get a black hole of mass 3 * 10^11 kg.

That may seem like a large number, but it's actually not even on a planetary scale. The mass of Earth, for example, is 5.972 * 10^24 kg. I couldn't find data on the mass of Vulcan, but according to Memory Alpha, with a surface gravity of 1.4 g, it is likely more massive than Earth (or at least on the same scale).

Therefore, when the singularity was originally released near Vulcan's core, the inhabitants would have barely felt anything at all. But as the magically stable mini-singularity sucked in matter near the core, the planet would begin to collapse in on itself to fill the void from the core out to the mantle and then to the crust.

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  • Would the singularity become more massive as it sucked in the planet, accelerating the process?
    – DCShannon
    Commented Jan 18, 2017 at 18:42
  • @DCShannon Yes. It will become approximately the mass of Vulcan.
    – DBPriGuy
    Commented Jan 18, 2017 at 19:40
  • Thanks! A well considered answer that addresses my question :)
    – Jane S
    Commented Jan 18, 2017 at 21:08

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