# How are quantum superpositions fundamentally different from ambiguous macrostates? **URL:** \ **Category:** Factual Questions\ **Created:** [March 11, 2011, 12:53am UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239 "2011-03-11T00:53:23Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [March 12, 2011, 9:32pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/21 "2011-03-12T21:32:17Z")
> [@](#): > > Moreso because presumably in the lab there are numerous atoms between the emitter, the double slits and the screen behind it. Why doesn’t the quantum probability collapse when the photon hits those objects in its travels? Because everything is composed of quanta and when quanta interact their wavefunctions form a superposition. > [@](#): > > Why does it seem a consciousness causes the collapse and nothing else? This is arguable. Von Neuman held that because everything is composed of quanta, and wavefunction collapse requires something that is not quantum based, then he held that that was human consciousness. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [March 12, 2011, 9:39pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/22 "2011-03-12T21:39:00Z")
> [@Ring](#): > > This is arguable. Von Neuman held that because everything is composed of quanta, and wavefunction collapse requires something that is not quantum based, then he held that that was human consciousness. This doesn’t work for me though since you can have a mechanical device doing the detection and mess the interference pattern up. A consciousness is a step removed. It seems the universe despises any kind of record keeping (e.g. anything that could record the photon going through one or the other slit). As long as we cannot know then the universe feels free to mess with our heads. But how could the universe know that? ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [March 12, 2011, 9:57pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/23 "2011-03-12T21:57:56Z")
> [@Whack-a-Mole](#): > > This doesn’t work for me though since you can have a mechanical device doing the detection and mess the interference pattern up. … And, could you explain how you know that without making an observation? ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [March 13, 2011, 10:40am UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/24 "2011-03-13T10:40:34Z")
But if human consciousness is not ‘made out of quanta’, how could it interact with something that is? The ‘explanation’ that consciousness causes collapse was never anything other than subbing in one mystery for another – we don’t understand how a classical world emerges from the quantum level, and we don’t understand how consciousness emerges from non-conscious processes, so hey, let’s just tape those two together! The problem is that explaining one mystery in terms of another mystery amounts to explaining nothing at all. Thankfully, we’ve since made great progress on both issues (in quantum mechanics mainly through the development of the decoherence picture, which produces the appearance of wave-function collapse while featuring nothing but unitary quantum evolution), so that it no longer seems necessary to wallpaper over our ignorance like that. ---
**Author:** ![Spatial\_Rift\_47](https://avatars.discourse-cdn.com/v4/letter/s/a8b319/32.png) [@Spatial\_Rift\_47](https://boards.straightdope.com/u/Spatial_Rift_47)\ **Post date:** [March 13, 2011, 7:36pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/25 "2011-03-13T19:36:36Z")
The current understanding in quantum mechanics of wavefunction collapse is that consciousness is not a necessary condition. Sufficient, but not necessary. Any physical interaction between a superposition and an external object will collapse the wavefunction. This is what **wbeaty** was talking about with the shadow coin interacting with air and ambient radiation. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [March 13, 2011, 7:52pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/26 "2011-03-13T19:52:50Z")
I’d like to see an actual quantum mechanics equation that has “consciousness” in it somewhere. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [March 13, 2011, 8:18pm UTC](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239/27 "2011-03-13T20:18:10Z")
Well, i \* h-bar \* d(|consciousness\>)/dt = H |consciousness\>. But I suspect that’s not what you were after — and, I suppose, assumes that consciousness is in fact describable in terms of a quantum-mechanical state. (Which I do think is the case, but I realize that there’s plenty of debate about this question.) [Previous page](https://boards.straightdope.com/t/how-are-quantum-superpositions-fundamentally-different-from-ambiguous-macrostates/574239.md?page=1)