Less Wrong is a community blog devoted to refining the art of human rationality. Please visit our About page for more information.

David_Gerard comments on PZ Myers on the Infeasibility of Whole Brain Emulation - Less Wrong Discussion

11 Post author: peter_hurford 14 July 2012 06:13PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (58)

You are viewing a single comment's thread.

Comment author: David_Gerard 14 July 2012 09:51:36PM 14 points [-]

I did like the test problem in the comments:

Take a preserved cell phone, slice it into very thin slices, scan the slices, and build a computer simulation of the entire phone.

Question: what is the name, number, and avatar of the third entry in the address book?

Now, how would you approach that one? Assume a known model of phone.

Comment author: ciphergoth 16 July 2012 08:17:30AM 4 points [-]

Looks like flash memory stores information using varying levels of charge; that would be quite painful to read out with a destructive scan. Happily that's unlikely to be the case with the brain's long-term storage, since AIUI it doesn't contain any sufficiently good insulators.

Comment author: siodine 16 July 2012 05:57:46PM *  3 points [-]

Freeze the volatile memory - - this preserves its state (you can retrieve passwords from shutdown laptops this way. an upside down can of computer cleaner will work). Slice it up, scan it (this assumes it wasn't significantly damaged while slicing; some damage is acceptable because what was there can be inferred -- this is a method in data recovery. also, you wouldn't slice it up tbh. probably the same with a brain.). With the scan you should be able to build a 3d representation of the memory with pixels (more information than just rgba). Now, you use some kind of pattern recognition to map patterns of pixels to physical representations (eg. take a Quake map and look for pixel patterns that match a jump pad).

Now, if you understood how the memory and cellphone software works, you could just get the state into a binary form acceptable for a cell phone emulator. But, because we don't understand how it works, we'll need to simulate reality to a sufficient level. I.e., we need an empty emulated universe with physical laws that correspond to our own, so that we can interpret pixels into their physical correspondents. So, when we pattern match a bunch of pixels into a memory cell with a certain state, we can then drop that interpretation into the emulated world.

For the emulated world to be sufficient for emulating the cell phone, I don't think you would need atoms or electrons (or anything below that level). You could probably emulate the components at the level of electricity, silicon, wire, gold, ect, because we can explain and predict the phenomena a phone produces at that level without going further. E.g., we just need to know what an electric current does, not what its electrons are doing to turn on an emulated light bulb.

(This was my internal monologue as I went through this problem. It's not researched, and is intended to be taken more as bar talk than anything very serious.)

Comment author: timtyler 14 July 2012 10:03:42PM 4 points [-]

Now, how would you approach that one?

Step 1 is to construct a superintelligent machine...

Comment author: [deleted] 14 July 2012 10:50:44PM *  2 points [-]

That seems feasible if you knew both the model and the operating system, and had a scan showing very precise relative temperatures. You could then match the state of the simulated phone to a long but finite list of the possible states of the phone given the operating system. But I'm not a doctor.

Comment author: Lachann 15 July 2012 12:49:55AM 2 points [-]

It's possible to directly read the state of transistors in the phone's memory via scanning capacitance microscopy (http://www.multiprobe.com/technology/technologyassets/S05_1_direct_measurements_of_charge_in_floating_gate.pdf), so you can reconstruct the actual contents of the memory. Probably the greater challenge would be figuring out how to cut the phone into slices without damaging the memory.

Comment author: jsteinhardt 16 July 2012 06:21:00AM 1 point [-]

Assume there are 20 apps on the phone, and each app can be in 5 states. Then this list is already 5^20 (or about 10^14) entries long. This doesn't include stored memory, as the address book would entail (number of possible names for the first entry of the address book is already something like 26^20 as a conservative estimate).

Comment author: jsalvatier 17 July 2012 04:38:38PM 0 points [-]