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Comment by simonh | Hacker News Reader

Well, there's the Marvin Minsky answer. He believed that there is no difference between a possible universe and a real universe. Think of the difference between an algorithm that only exists in theory and running the algorithm on a computer. What do we add to the result by running it? We don't change the result, or grant it any greater validity in a metaphysical sense. The answer was always going to be the same and always will be the same. Minsky thought that our world is simply a possible world, but to suppose it is 'real' or not doesn't change anything and more than doing a calculation makes the result correct. It simply is.

It's similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the 'present' is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.

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> It's similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the 'present' is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.

Labeling something an "illusion" like that seems like a massive cop-out, made by a mapmaker to avoid confronting the fact that their maps don't fully represent the territory. Fossils weren't illusions, and I don't think the present or existence are illusions either.

If a surgeon pokes your brain in the right place, that desk in front of you will disappear. You aren't experiencing reality directly, as per Plato's Cave. Reality seems precisely to be an illusion.

It isn't clear to me what you mean by "illusion". I generally interpret "illusion" to mean that things appear to be contrary to how they are. That is, an illusion is a way in which appearances are contrary to reality. But to say that "reality is an illusion", would then be to say that "reality is a way in which appearances are contrary to reality." . Which, appears to be nonsense.

I suppose if what you mean by "reality" is "perception", and if what you mean by "illusion" is also "perception", then what you mean by "reality" and "illusion" would be the same thing, namely, "perception", but, I don't think that's what you mean?

You choose the word "contrary" but a more accurate word is probably "different". The underlying nature that drives input to our senses is absolutely different from our day to day experience of three dimensional objects with distance. The underlying physical nature appears to be one of non-locality, and properties like shape and color are synthesized by your mind rather than inherent aspects of nature.

But even these models of an objective reality that come from quantum physics are not direct, as you had to build them in your mind through information you received through your senses, so this sense of an objective reality outside of your mind is also an illusion.

Well, what would it look like if the earth went around the sun instead of looking like the sun going around the earth?

They both go around each other.

The desk is still there, as confirmed by outside observers. If you are blind, is everything you touch non-existent?

How do you know about "outside observers" other than through a model you formed in your mind by data received through your senses? "Objective reality" is just another shadow on Plato's wall that can be extinguished.

Nihilism is neat until you realize it makes not testable predictions. So sure, everything could be totally an illusion and your brain is hooked up to a computer somewhere (or it is a computer). That’s a metaphysical claim that’s not falsifiable and doesn’t even make any useful predictions.

That’s not particularly relevant to a discussion about science and the Big Bang. In science we assume that multiple measurements by multiple people of the same phenomena gives us a good idea of the behavior and whether it matches our models. Our models will likely forever be incomplete but throwing our hands up in the air and trying to say “yes, but do we really know that” doesn’t seem helpful.

What if I am a few light-seconds away from the desk, so nobody "there" can confirm it exists "now"?

It’s a pleasing cognitive answer, but doesn’t really fit well with math or physics. Time is an emergent property of the Universe that we can measure and compare with a more platonic mathematical model of time. Also, you could make the argument that Minsky’s argument is just a form of discontinuity.

Greg Egan's earlier book Permutation City is a pretty interesting exploration of this concept in fiction.

Do you have a citation? I never heard of Minsky espousing this view. Could you be confusing him with Moravec? (https://frc.ri.cmu.edu/~hpm/project.archive/general.articles...)

Sure, he explains it here. All his interviews on Closer to Truth are worth watching, but then I'm a fan of the show. I don't know if the idea was original to him.

https://www.youtube.com/watch?v=PUbANEalnzc

Thanks, I'll also watch it later. It initially reminded me of Tegmark's levels of parallel universes (http://arxiv.org/abs/astro-ph/0302131) whose highest is one that assumes mathematical reality is the same as physical reality.

Thanks!

Wow cool thanks, I am reading about block time now. Weird thought, if time is a dimension, and the universe is inflating, could our perception of time advancing simple be a result of inflation in the time dimension?

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