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This article is about the quantum event. For the ensuing battle, see Black Mesa Incident.
"I never thought I'd see a Resonance Cascade, let alone create one..."
Black Mesa scientist[src]

The Resonance Cascade is a cataclysmic quantum event created after the insertion of Xen crystal sample "GG-3883" into the Anti-Mass Spectrometer at Black Mesa by Gordon Freeman, culminating in the Black Mesa Incident.



Vortigaunt being teleported into Test Lab C-33/a during the Resonance Cascade.

According to notes from Gordon's desk, every object has a set resonance. When excited by specific forms of energy of the correct frequency, it will resonate and the amplitude of the vibrations will grow. If crystals (such as those from the Border World Xen) resonate beyond a certain threshold, it can open dimensional rifts and portals.[1] The Xen crystal sample studied at Black Mesa resonated strongly enough to tear a rift between Xen and Earth.

While appearing to have been a contained event, it did, in fact, have repercussions across the entire planet. The Resonance Cascade was the cause of not only the inter-dimensional rift but also all following events. It later sparked Portal Storms across the Earth and ultimately led to the Seven Hour War and opened the way for the Combine invasion of the planet.

The Resonance Cascade is therefore arguably the single most significant event in the entire Half-Life timeline, as every single event that takes place across the entire series can be traced back to it, as a common root cause.


Half-Life and its expansions

The Resonance Cascade caused an aggressive rift to form between the Xen border world and the Black Mesa complex on Earth in 200-. While at first only basic Xen wildlife, such as Headcrabs and Barnacles seemingly emerged through the rift, other intelligent creatures, such as Vortigaunts, were also sent to the other side by the Nihilanth, leader of the Xen forces.

The phenomenon was self-sustaining and would thus continue until action was taken to terminate it, and Gordon Freeman, being the one who caused it, took upon himself the job of closing it. The rift appeared to have closed on Earth's side after the surviving Black Mesa science team, including Freeman, took steps to re-initialize Black Mesa's satellite-based energy projection network (including replacing a missing satellite by launching an orbital rocket carrying a replacement satellite). However, the remaining scientists from the Lambda Core discovered that, despite their efforts, the portal was being held open from the other side by an unknown entity: the Nihilanth. As a counter-measure, Freeman armed and equipped himself for an expedition, then traveled to Xen via a portal prepared by the science team to neutralize the Nihilanth. His success in the endeavor eliminated the factor that was keeping the portal open, finally closing it on both sides.


List of appearances


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