Legend has it, that an alien lifeform has brought civilisation to our world, and over the last decades you've been following hint after hint to track this legend down. From all you've been gathering, it seems these aliens can access a 4th dimension in space, and that they have long left this world through a gateway.

It was always your aim to find this gateway and to follow them into their world, and today, all your hard labour has finally paid off. You stand in front of the mythical gateway chamber deep down beneath the highest mountains of the world, and as the stone slabs slide noisily out of your way, you get a first glimpse of a half-dome shaped cavern.

Immediately your gaze is drawn to a strange apparatus in the centre of the cavern. This must be the gateway, no doubt! As you walk towards it, you notice the ceiling of the dome has some inlaid mosaic in deep-black stone, and a bluish shimmering metal, giving the impression of a stary night.

The apparatus in the centre has a rather crude and simple mechanism consisting of three wheels only, and each of the three wheels has 13 positions marked with strange symbols. You immediately notice that the symbols match the 13 symbols on the ceiling. No doubt, that adjusting the appropriated combination will open the gateway, but if you're research has been right, there is only a single point in time every 13 years when the portal can be opened, and this moment is soon to come. So you have a single chance to get the combination right. You also notice, that on top of each wheel another symbol is scratched in, outlined with a simple frame. What could that mean? This all has the touch & feel of a test. It seems the aliens do not let anybody into their dimension.

As you search for clues on the combination, you find a little alcove at the back of the apparatus which also contains a flat stone panel with some inlaid metal pieces, which shimmer silvery in the light. You step closer and watch the panel carefully, as you're convinced it holds the key to the combination...

## Can you find the combination to get the gateway going?

This puzzle is solely contained in the three images below. The aim is to find the correct combination of symbols to activate the gateway, i.e. you need to find for each wheel the correct symbol out of the 13 symbols shown on the 'ceiling'.
Partial answers (and speculations) are welcome and will be commented upon.

The ceiling:

( Full resolution image )

The device:

( Full resolution image )

The panel:

( Full resolution image )

• ...but I'm supposed to be working, BmyGuest... you're not helping. Mar 21, 2016 at 2:31
• Also, is there significance that one of the component shapes (which I've dubbed "zero", and shows up on what I've labelled symbols 2, 3, 4, 5, 7, 9) doesn't appear in the background of the ceiling? Mar 21, 2016 at 4:01
• I started by scaling the panel to a width of 500 pixels.
– Carl
Mar 21, 2016 at 19:24
• @BmyGuest it makes the size of the shapes on the ceiling equal.
– Carl
Mar 21, 2016 at 19:53

After staring at the otherworldly shapes for hours, you slump in despair, still no closer to understanding. Glancing at your watch, you realise you're out of time. Perhaps you're just not worthy of passing this test. Maybe in another thirteen years, you'll have another chance.

"Damn it!", you cry, as you hit the centre dial in sheer frustration. It spins freely for a few moments and comes to rest... Suddenly there's a great rumble and the symbols begin to glow.

The whole room begins trembling, causing dust and fragments of the metallic inlay to fall from the ceiling. The whole place is starting to crumble. The glow from the symbols continues to increase as it starts to consume everything. You squint against the brightness, and realise the portal is opening.

But how?! As the light of the opening portal grows, you frantically look again at the panel on the rear of the apparatus, desperate to comprehend. Perhaps it's the influence of the portal, but this time when you look, understanding floods your mind.

You remember the fragmented shape at the very centre of the ceiling, and recall thinking that it looked like a representation of a cube. And now, seeing the panel again with this higher dimension in mind, you see the unfurled mesh of a three dimensional object, with projected faces matching the ones on the dials and ceiling.

More importantly, you see that the three square faces of the object, when mirrored, match the three symbols above each dial (1, 2 & 3 respectively):

[Ed - here's a more complete visualisation from OP, showing the individual shapes projected onto the actual 3D object]

As the mesh folds and takes its 3D form in your mind's eye, you realise... If you were looking through the object, the far face, would appear mirrored, just as it does above the dials. When that's the case, the projection formed on the closest faces would create another symbol, displayed in the correct orientation in the foreground. Looking at various shapes you see that they do indeed match to the symbols seen on the dials, and on the ceiling:

You look again at the symbols above each dial, and see that what you first took to be borders around each, in fact show a projection of a cube hinting at the three dimensional nature of the puzzle. Looking down at the position of the dials themselves you see the three symbols that appeared opposite on the folded object. The first and last dial were already in the correct place, leaving only the second to be turned, but your sheer dumb luck, into the correct position.

You smile at the great irony of your worthiness and close your eyes, as the portal's brilliance envelopes you...

• +1 for style! A minor thing, though: If you check the panel closely, you'll realize that you see a mesh expanded, and if you "fold it up" (to higher dimensionality ;c)) you will not quite get a cube... but the remaining argumentation is correct. Are you going to amend this solution or should I? Mar 22, 2016 at 13:31
• This image could come in handy... Mar 22, 2016 at 13:34
• @BmyGuest - Ahh, our poor dimwitted protagonist. Still didn't quite get it. ;) I'll update. I wonder if I would have realised if I printed it out and tried physically folding it (drew the line at doing papercraft at work, so did it mentally). BTW, on a personal note, this is a great puzzle! Very difficult, but enough clues buried in the detail to draw you in. Deserves more upvotes/views (pity I can't give a bounty to a question). Mar 23, 2016 at 0:31
• I wish I could pay rep to up vote this again. Very clever! Mar 23, 2016 at 1:38
• Thanks. Seeing your nicely compiled answer in style and knowing it was a good, enjoyable puzzle is more worth than rep. Love the fact that I made you think twice because 2/3 of the solution were already in the image :-) btw, the missing 0-element was a minor clue/restriction as it is not used in the 3 answer symbols. I hope to lure some people into doing maths. 9 symbols, 3x3 grid... Mar 23, 2016 at 8:24