Computer folk often use the terms emulation and simulation to mean two different things, which Myers appears to be conflating. In the sense I’m thinking of, simulation means modeling the components of a system at a relatively low level — such as all the transistors and connections in a CPU — whereas emulation means replicating the functional behavior of a system.
(Of course, these terms are used in a lot of other ways, too. SimCity is neither a simulation nor an emulation in the sense I’m using.)
For instance, a circuit simulator modeling a piece of RAM might keep track of the amount of charge in a particular capacitor that represents a particular bit in memory; but an emulator would just keep track of what numerical value was stored in which addressable location. An emulator doesn’t attempt to replicate how the original system works, but rather what it does.
(A non-computational analogy: An artificial heart doesn’t duplicate the muscle cells of a natural heart; it duplicates the function of a heart, namely moving blood around. It’s not necessary to copy the behavior of each individual muscle cell — to say nothing of each molecule in each muscle cell! — in order to duplicate the function of a heart well enough to keep a person alive for years.)
From what I’ve read, folks who expect WBE don’t expect modeling at the molecular level (a simulation of a brain), but rather at some higher functional level (an emulation, hence the term), so much as that some sort of functional components — maybe individual neurons; maybe specific brain regions — can be emulated without simulating them.
In the sense I’m thinking of, simulation means modeling the components of a system at a relatively low level — such as all the transistors and connections in a CPU — whereas emulation means replicating the functional behavior of a system.
The term emulation originates in computer science, where it denotes mimicking the function
of a program or computer hardware by having its low‐level functions simulated by another
program. While a simulation mimics the outward results, an emulation mimics the internal
causal dynamics (at some suitable level of description). The emulation is regarded as
successful if the emulated system produces the same outward behaviour and results as the
original (possibly with a speed difference). This is somewhat softer than a strict mathematical
definition1. [...]
By analogy with a software emulator, we can say that a brain emulator is software (and
possibly dedicated non‐brain hardware) that models the states and functional dynamics of a
brain at a relatively fine‐grained level of detail.
In particular, a mind emulation is a brain emulator that is detailed and correct enough to
produce the phenomenological effects of a mind.
The low-level simulation of equipment or phenomena by artificial means, such as by software modeling. Note that simulation may also allow an abstract high-level model.
Emulation is the process of mimicking the outwardly observable behavior to match an existing target. The internal state of the emulation mechanism does not have to accurately reflect the internal state of the target which it is emulating.
Simulation, on the other hand, involves modeling the underlying state of the target. The end result of a good simulation is that the simulation model will emulate the target which it is simulating.
Fair enough, although multiple people downvoted that comment (it seems to have had some upvotes since to compensate). Even if they downvoted for different reasons though, that’s still at least one counterexample of someone who fits into the category “folks who expect WBE”.
Emulation without simulation would require not only vastly more understanding of the brain and of cell biology than we have now (most of the problems Myers points out would still be there, though not all) but on top of that all the problems you hit when trying to emulate one system on another, plus a whole lot of problems no-one’s ever even conceived because no-one’s ever ported an algorithm (for which we have neither source code nor documentation) from a piece of meat to silicon.
Computer folk often use the terms emulation and simulation to mean two different things, which Myers appears to be conflating. In the sense I’m thinking of, simulation means modeling the components of a system at a relatively low level — such as all the transistors and connections in a CPU — whereas emulation means replicating the functional behavior of a system.
(Of course, these terms are used in a lot of other ways, too. SimCity is neither a simulation nor an emulation in the sense I’m using.)
For instance, a circuit simulator modeling a piece of RAM might keep track of the amount of charge in a particular capacitor that represents a particular bit in memory; but an emulator would just keep track of what numerical value was stored in which addressable location. An emulator doesn’t attempt to replicate how the original system works, but rather what it does.
(A non-computational analogy: An artificial heart doesn’t duplicate the muscle cells of a natural heart; it duplicates the function of a heart, namely moving blood around. It’s not necessary to copy the behavior of each individual muscle cell — to say nothing of each molecule in each muscle cell! — in order to duplicate the function of a heart well enough to keep a person alive for years.)
From what I’ve read, folks who expect WBE don’t expect modeling at the molecular level (a simulation of a brain), but rather at some higher functional level (an emulation, hence the term), so much as that some sort of functional components — maybe individual neurons; maybe specific brain regions — can be emulated without simulating them.
There seems to be conflicting usage about this.
http://www.fhi.ox.ac.uk/__data/assets/pdf_file/0019/3853/brain-emulation-roadmap-report.pdf
https://secure.wikimedia.org/wikipedia/en/wiki/Emulation
On the other hand, the top-voted answer at http://stackoverflow.com/questions/1584617/simulator-or-emulator-what-is-the-difference says that
Well, when I argued on here last week ( http://lesswrong.com/lw/d80/malthusian_copying_mass_death_of_unhappy/6y2r?context=1#6y2r ) that emulation would be more difficult than people imagine, based on my experience of working on software that does that, people downvoted it and argued “no, people aren’t talking about emulation, but about modelling at the molecular level”
Hmm … from my reading of that conversation, one person said that.
Fair enough, although multiple people downvoted that comment (it seems to have had some upvotes since to compensate). Even if they downvoted for different reasons though, that’s still at least one counterexample of someone who fits into the category “folks who expect WBE”.
Emulation without simulation would require not only vastly more understanding of the brain and of cell biology than we have now (most of the problems Myers points out would still be there, though not all) but on top of that all the problems you hit when trying to emulate one system on another, plus a whole lot of problems no-one’s ever even conceived because no-one’s ever ported an algorithm (for which we have neither source code nor documentation) from a piece of meat to silicon.