When I was around twelve or thirteen, I remember my mom cooking something in the kitchen.  It was some kind of roast in a big glass pan. She added some water to the pan so the meat wouldn't dry out. KABOOM. The glass exploded.

Why? The scientific explanation is that glass expands and contracts with temperature change. Unlike metal which is relatively soft and flexible, glass is brittle (that's why it shatters). If you change the temperature too quickly the glass breaks. That's what happened to the pan with the roast. System shock.

Interestingly, this effect frequently occurs in nature--not just the kitchen. Evolution for example, relies on a specie's ability to acclimate to change. Anything too abrupt (asteroid) and it could mean extinction. Even our own bodies have instinctive coping methods for shock.  E.g. if your core temperature drops too low or you encounter extreme amounts of pain you subconsciously enter "shock". That's why when you jam your finger in a door it feels numb, not that I know from experience or anything.

Fearing rapid change is natural. It's something I struggle with all the time. If things start moving too fast, I no longer feel "in control" and begin to fear potential system shock--that is, so much change that I metaphorically explode. I used to make the dentist use one tool at a time because I got nervous if things started whizzing and prying all at once. They loved taking so much time to accommodate my fear.

To overcome system shock it's best to adapt a "metal philosophy" rather than glass. If you're able to expand with the heat, bend with change, etc. then you'll be less likely to shatter. It's easier said than done but simply being aware of this phenomenon helps me when fear arises. I play out the worst case scenario in my mind which usually isn't as bad as it initially seems. From there I just try to breathe and remind myself that it will be OK.

For the record, my mother is a wonderful cook.