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Comment by deepnotderp | Hacker News Reader

For anyone interested in this, the Landauer limit now has experimental evidence.

Also, it is now believed that the Margolus-Levitin theorem puts a lower bound on energy even on reversible computations.

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Weird. It's new to me that we didn't have experimental evidence before, but I guess it would have to be pretty subtle equipment.

I wish I knew how to catalog/index my assumption/belief set, so I could scrub it down for unverified sub-assumptions from time-to-time. I'm happy to update them, when they are proven wrong, but I don't know how to do this methodically and as a result, my brain fills up with crap. And then I can't trust my own glib reasoning, and then I have to be methodical for anything I need to think through, and that slows me down. And I hate that.

Your brain is not a computer

And yet both of them start to degrade when I spill alcohol on them.

Perhaps you are unaware that the term "computer" originally referred to a person who performed scientific calculations by hand (using their brain).

https://www.amazon.com/When-Computers-Human-David-Grier/dp/0...

We have no scientific evidence of any process in and brain or mind which isn't computable in the sense of Church/Turing. On the other hand I personally feel that I experience episodes that couldn't be computed, but I struggle to articulate the smallest parts of these. One is the small creative epiphany of writing, the structures of with can be created computationally, but the turns of sense and narrative don't seem to me to be the outcome of functional transformations.

I know that others will hold to the idea that they are and could be, but to me that renders us as zombies, and that isn't satisfactory in the sense that while a zombie that acts like a real person would be evolutionary fit, I see no reason why the zombie should believe it has free will, or could, and yet I do.

The zombie could believe it has free will the same way it holds any other belief - whether it happens to be a delusion is immaterial to whether it's able to hold the belief and there's nothing particularly unique about this particular belief. It's also far from implausible that belief in free will could have some evolutionary utility (or, more likely, be a concomitant of some other property that has evolutionary utility). None of this proves you wrong, of course, I just don't see why we should imbue our common sense intuitions in this one area with such authority when they have failed us in so many others.

There are quite a few things in physics which didn't have direct experimental evidence, while most are convinced because the theoretical results and incomplete evidence are persuasive enough. If this Science article is accurate, there was no direct experimental evidence that proved the majority energy of the Sun comes from the fusion of protons into helium, until the neutrino experiment in 2014.

https://www.sciencemag.org/news/2014/08/underground-experime...

Woah!

"They did a stellar job..."

Well ... yes, yes they did.

Pretty fascinating, if light, overview of what's involved in neutron detection. A case of understanding theoretical models (causal knowledge), materials, purity and processing, conversion processes (neutrino interaction -> light -> photodetector), statistics, and ultimately, a view of what was happenning inside the solar core eight minutes ago, events which won't manifest on the solar surface for another 100,000 years.

> the theoretical results and incomplete evidence are persuasive enough

In the quoted example, "direct evidence" from that paper was not necessary to confirm that the other calculations and models match. The achievement presented in that paper was to measure the specific neutrino flux, but there were many other measurements before that matched the developed models and weren't less convincing.

It's always good to read more than only journalist's interpretation. Here's from the paper itself:

Eve before "solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations."

Only "those from proton–proton fusion have hitherto eluded direct detection."

https://www.nature.com/articles/nature13702

The paper itself stated that the reactions in the Sun were already proved.

The foundations of our knowledge are very quickly based on assumptions/beliefs.

Light is not really understood. It's a wave and a photon, depending on what we need to solve. We incorrectly say light is a "wave", but "wave" is a verb!! I remember thinking this sounded ridiculous when I was in school. You probably did too! We should all go back and redo our assumptions like you say.

The other thing that disappointed me was the explanation of why magnets attract/repel. (Do you remember your feeling about it? Did your innocent child mind reject the explanation?)

Light is well understood but the explanation depends on what level of abstraction you require. There are quantum, classical and naive explanations of light and each are radically different. It's not our understanding that is flawed but rather the assumption that if there's two different explanations of the same physical phenomenon it indicates a lack of knowledge (rather than an abundance of knowledge).

That just moves the problem to "which layer of abstraction should I use". Ex. If I'm developing a new material that interacts with light, should I consider light to have mass, or not? Well if it's a space sail, photos have mass, if it's not a space sail, light has no mass. But I'm not sure if this new material is a space sail....which abstraction should I use?

It's hard to imagine what it would even mean to get experimental evidence against the Landauer limit. You'd have to throw out basic thermodynamics. (It would about the same as getting experimental evidence for a perpetual motion machine; possible, but basically requiring a revolution in fundamental physics.) The disputes over the Landauer limit were conceptual and definitional disputes, not disagreements over well-formed predictions.

On average, you can demonstrate the landauer limit.

https://advances.sciencemag.org/content/2/3/e1501492

Even in those experiments, there are scenarios where energy is recovered during the erasure of the bit. Although the number of experiments is large enough to recover the k_b T ln(2) expected value.

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