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While we're here, can someone explain how a "dream within a dream" works in Inception ? Presumably someone has to "fall asleep" inside their (or someone else's) dream and go into a dream state again on another level so to speak. The only way I can see the brain implementing that is to dream of its own state so completely that it can run itself as a virtual machine, and fall asleep inside that VM. I haven't read the code, but I doubt the C implementation includes a VM that can run inside itself, Smalltalk-style.

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> While we're here, can someone explain how a "dream within a dream" works in Inception ?

Exactly like that. It happens in real-life and no doubt that's where they based it from. It happened to me a couple of times already, the deepest I got was 4 levels.

Real-life sleeping > level 1: sleeping > Level 2: sleeping > Level 3: sleeping > level 4: awake

Usually, it was very bad. A form of nightmare. You slowly get aware of it, even to the point that your brain tells you that you are awake. Then when something happens that you want to wake up (for example, you died, or you suddenly got aware you're sleeping), you will indeed wake up, up to the next level.

Once again, your brain will tell you that you are finally awake.

The first experience I had of this was when I was barely a teenager. It was a nightmare within a nightmare within a nightmare within a nightmare. When I got fully aware I was sleeping, that's when I fought, waking up, then waking up, then waking up, then finally waking up to the real world.

Problem was, I was no longer sure if it was the real world I woke up to. To this day, I sometimes think I am still sleeping.

Just like the other ending in Inception. Hence I love that movie. I can relate.

> To this day, I sometimes think I am still sleeping.

This is a well-known problem in the lucid dreaming community. There are some surprisingly easy ways to check. I find the simplest is to count my fingers out loud. If there are definitely five on each hand, then I'm awake. If there's any problem coming up with a count, then I'm asleep, no matter how much it seems like I'm awake.

Unless that's just a feature of the deeper dream levels, not this one...

(I also have dreams where I wake up over and over and over, only to realize that shit, I'm still dreaming. It's surprisingly disconcerting, there's a kind of physical sense of losing my mind involved.)

Honestly you could just lack the awareness to notice. That's not a slight against you, acute awareness in the dream state is not an innate ability and must be practiced frequently in order to be successful with it.

In any dream state, you can test the rules of the world around you and see that your brain doesn't quite build the world to completeness. Light switches will not work, text will morph and shift either in front of your eyes or when you look away and turn back, the people around you will spontaneously morph into others, you can breathe through your nose when it's plugged, etc.

What happened to you is referred to as a false awakening. Testing the reality of your situation by checking clocks, breathing through your nose, counting your fingers, etc. will all quickly put you into a more lucid and aware state. From there you either continue or, more commonly, you wake up.

> Testing the reality of your situation by checking clocks, breathing through your nose, counting your fingers, etc. will all quickly put you into a more lucid and aware state.

I haven't thought of that. What became my anchor for the past few years have been my schedule or being aware of it.

But there were rare cases when in my dream state, the reality is happening in the dream and that totally puts me off greatly. A good example is when I'm dreaming I woke up, went to work, and got home.

When I woke up, I didn't know until I arrived at the office and learned no day has passed yet.

Ooh, interesting. I learned to lucid dream in my late teens or early 20s and I've enjoyed it most of the time (except those times when I'm losing control).

It's true, if you're too much into lucid dreaming, there are times when you can't tell if you've woken up. Parts of the dream spill overs in the waking world.

Does pulling your hands in opposite directions work for you?

It worked for me once and I got really excited. Too excited and woke up :(. Never happened again (not that I've been trying).

one time i tried this and each of my fingertips turned into little hands with the same dexterity of my hands. needless to say i believe i was asleep.

Once after I spent the whole day writing a parser in Haskell I had a dream in which I was falling asleep under a tree, but such that first my torso fell asleep, then my arms/legs, then my head, fingers, toes, etc. Cracked me up.

I used to get those as well as a kid. The technique, nightmare-within-nightmare was a trope of 80s horror movies and that's where we got it (incepted?) I believe :)

On the movie, I think the really interesting part was not the recursive dreaming but rather how our ideas- that we think are novel - are not actually ours. After watching it, me and my wife started observing it on each other. Me or she would come up with something and the other would point out some conversation in the recent past that seeded it. Fun and a bit scary.

True. In the creative writing world, there is this notion that we are all pulling the ideas from our stories in some alternate space where ideas freely flow.

And when we notice how our original idea (and we're sure it's the first) is too similar to another who beat us to publication, yet both parties are sure no one copied anyone... well, it gives credence to the idea that there is an alternate space out there... or maybe we can access each other's ideas on some quantum level.

Speaking of quantum level, it might even be possible altogether.

I had that happen once. In this dream, I was in a 'fake' world that had some kind of trick or flaw to it. When I found the trick, that world disappeared and I found myself in another world with a different trick. This went on all night, I think there were at least four of these worlds before I actually woke up. It messed with my head for a while.

“There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened.”

— Douglas Adams, The Restaurant at the End of the Universe

Ooh, interesting, very interesting! (And scary)

Another movie with the same theme is Waking Life. I also found it a lot more thought-provoking than Inception.

http://www.imdb.com/title/tt0243017/

Thanks, I'll watch it!

That sounds horrifying.

Yep. And the nightmare, of all things, is Dracula and vampires. I'm aware of Dracula, but vampires, didn't even know that term then (early to mid 90s).

when the first dream "forks" and the new dream narrative starts, are you aware that this new dream is "inside" the host dream ?

Nope. Usually when I first become aware of the dream world, I am already levels deep. The only time I became aware of those levels is when I start to wake up and I ended up still being in a dream totally different from the level I woke up from.

I've been trying to figure out how to know I am levels deep but to no avail.

It is like falling asleep in a Docker container. You don't know what is outside of the container and you don't know where you are because kubernetes doesn't tell you. Everything is abstracted.

This is pretty neat overview though: http://www.inception-explained.com/

Inception as a set of commands to start and stop docker containers within docker containers, and programs within those containers. As a bonus, the last command should be trying to determine if the top level is a docker container, and segfault.

Time moves faster in a dream than it does in the real world.

Code running in a container runs slower than in the outside world ;-)

It's a plot device that is left unexplained.

Nolan tends to write really, really, really soft scifi.

His trick is to have characters who sound SUPER sure of what they're doing. Winking at the camera, looking determined, talking total bullshit but it doesn't matter. You want to believe it makes sense because it all feels so cool!

For me it was even more distressing that this is somehow a thing you can do, but you can only go 3 levels then something completely different happens. Why 3? Why not 15? For something like this to be the case, it would require the brain physically designed to perform these functions.

Yep it's dreaming within a dream exactly. I've had it happen to three levels deep (assuming this world is real). Woke up then woke up again, then woke up a third time and now I'm in this world.

User-mode Linux was capable of self-hosting. There's always that.

UML inside UML doesn't work for me:

  $ linux
  Locating the bottom of the address space ... do_syscall_stub : ret = -1, offset = 1052680, data = 18ca9008
  do_syscall_stub: syscall 192 failed, return value = 0xffffffff, expected return value = 0x1000
      syscall parameters: 0x1000 0x1000 0x7 0x11 0x3 0x2449
  Failed to flush page for address 0x1000
  Killed

I was fairly certain I had done it before. I did some Googling to sanity-check myself and found, "UML can be compiled to run within UML" [1]. I don't seem to recall any unusual compiling options to make it work, but then that was a long time ago, as was that document, I suspect (although it has no dates). Maybe it's broken...

[1] http://user-mode-linux.sourceforge.net/old/UserModeLinux-HOW...

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