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Quantum Capacitance: Overcharge it anyway.

Remote Detonation: Kill a Barnacle with a Satchel.

Unified Coupling Theorum: Help the Barnacle and Headcrab find true love. [0/10]

Permeable Infrastructure: Use the alternative path in the Office Complex.

I'm having trouble with these four in Black Mesa: Source. I have already completed all the other achievements, but these have stumped me.

What exactly is a Barnacle? Do they mean Headcrabs? I'm very confused.

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Hi, Retrosaur. Asking about every single achievement is a bit much for a single question. As such, I'm reverting to your earlier revision, which listed only 4. Even that's pushing it a bit, though; you might have better luck asking 4 distinct questions, talking about what you've tried already, etc, if you're hoping to get the best answer. – Raven Dreamer Oct 11 '12 at 2:52
Barnacles are the alien monsters that you see attached to the ceiling with a long slender grey "tongue" stretching down nearly to the floor, which they use to reel in their prey (or you). I haven't gotten the achievement but I suspect you need to get headcrabs to walk or jump into the barnacle's "tongue". – Dan C Oct 11 '12 at 3:20
up vote 3 down vote accepted

Quantum Capacitance

Hold the secondary fire button of the Tau Cannon weapon (right-click, by default). The weapon will then overcharge if you hold it for some time (you will know this as your health and shield will take a hit).

Remote Detonation

This is a barnacle

enter image description here

And here is a satchel charge:
enter image description here

Kill one of the former, with the latter.

Unified Coupling Theorum

Lead a headcrab to a barnacle's tentacles and have the barnacle eat/kill the headcrab.

Permeable Infrastructure

There's an alternate route through the vents in the Office Complex chapter. You need to go through that route to get this achievement. See this Youtube video on how to find that route:

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