Help Me Figure Out What This Book Was Called

When I was younger I read a book. I have no idea what it was called or who wrote it or what the character’s names were. All I can remember is that some kids (middle school or high school) figured out some way to, or found some device which allowed them to, enter a higher dimension. As I recall it was still our universe but there were additional dimensions (or maybe just one extra) on top of the usual three. This sounds crazy because I can’t remember enough about it to explain it correctly.

I do remember that they were able to use this dimension-skip thingy to get past a locked door. The door led to a rooftop at their school, I think. Also, one of the kids had a ketchup packet in his pocket. When he took it into this other dimension and then brought it back, then tried to eat it, it tasted like expensive chocolate instead of ketchup, or something.

I read this book sometime before I turned sixteen. This tells me that it had to have been published before 2000.

Does anyone have any idea what I’m talking about?

I googled for “ketchup chocolate dimension” and this was the second result:

Hey, that wasn’t there the last time I searched… but that was a little while ago and maybe I didn’t use the right keyword combo. Thank you, that is the one!

Isn’t time the fourth dimension?

Damn you, Mithras, I remember this one and you beat me to it. Yes, that has to be “The Boy Who Reversed Himself.” If you Google the title you can see a longer description.

It depends on what you’re trying to do. Graphing your position in relation to time makes more sense in most situations than it does to graph it in relation to temperature, but if you’re a scientist studying how humans react to temperature, they might well use that as their fourth dimension.

(And of course, the first three dimensions don’t necessarily need to be positions in space, either.)

I just got home a short time ago, and found this thread an hour too late to beat Mithras with the answer. I’m right behind Marley, shaking my fist at you with the wailing and the gnashing of the teeth, even!

William Sleator totally fucking rocks! If you can find a copy of House of Stairs, buy it; you won’t regret it. It’s one of his best, and is a story that is, IMO, impossible to forget.

Let me ride on your coattails.

Now help me identify I book from about a decade ago.

In it a woman develops some sort of portal/wormhole of unknown properties. She starts shoving things into it. Some things go through the portal and disappear, others won’t go through. The mystery is why a chocolate bar will go through but a packet of nuts won’t for instance. Eventually she tries to go through, but can’t, yet her boyfriend is able to pass through. Turns out the wormhole mirrors her psyche somehow and only things she loves can pass through.

That’s all I remember. Any ideas?