gilch

Karma: 2,457

gilch 19 Apr 2024 20:07 UTC
5 points
3
in reply to: ProgramCrafter’s comment on: hydrogen tube transport
Hydrogen can only burn in the presence of oxygen. The pipe does not contain any, and combustion isn’t possible until after they have had time to mix. It’s also not going to explode from the pressure, because it’s the same as the atmosphere. The shaped charge is obviously going to explode, that’s the point, but it will be more directional. That still doesn’t sound safe in an enclosed space. Maybe the vehicle could deploy a gasket seal with airbags or something to reduce the leakage of expensive hydrogen.

gilch 19 Apr 2024 19:59 UTC
3 points
−2
in reply to: bhauth’s comment on: hydrogen tube transport
Condensation is not just possible but would happen by default. You described the tubes as steel lined with aluminum in contact with the ground, if not buried. That’s going to be consistently cool enough for passive condensation.

Getting water out of a long tube shouldn’t be hard with multiple drains, and if there’s any incline, you just need them at the bottom. You can just dump it in the ground. Use a plumbing trap to keep the gasses separated. They’re at equal pressure, so this should work, and the pressure can also be maintained mostly passively with hydrogen bladders exposed to the atmosphere on the outside, although the burned hydrogen will have to be regenerated before they empty completely, but this can be done anywhere on the pipe. Hydrogen can be easily regenerated by electrolysis of water, which doesn’t seem any more expensive than charging the batteries. It might be even cheaper to crack if off of natural gas or to use white hydrogen when available.

Are turbines more expensive than electric motors for similar power? It’s true that conventional piston engines are heavy, but batteries are also heavy, especially the cheaper chemistries.

Alternatively, run electricity through the pipe to power the vehicles so they don’t have to carry any extra weight for power. It’s coated with conductive aluminum already. If half-pipes could be welded with a dielectric material and not cost any more that would work. Or use an internal monorail, but maybe only if you were going to do that already. Or you could suspend a wire. That’s got to be pretty cheap compared to the pipe itself.

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gilch19 Apr 2024 4:16 UTC

6 points

1 comment1 min readLW link

(youtu.be)

gilch 19 Apr 2024 3:29 UTC
3 points
0
on: hydrogen tube transport

A vehicle in a hydrogen-filled tube can’t use air around it for engines

Why not? Your “fuel” tanks could simply carry oxygen to burn the surrounding hydrogen “air” with.

and shouldn’t emit exhaust.

Exhaust would be water vapor, easily removed even passively via condensation and drains. Hydrogen will (of course) have to be replaced to maintain pressure.

gilch 18 Apr 2024 17:18 UTC
4 points
0
on: Reconsider the anti-cavity bacteria if you are Asian
The oral flora contains a diversity of organisms, bacterial, viral, and fungal, including some yeasts. Don’t some of them produce ethanol already? And adhere to the mucous membrane instead of enamel? It wouldn’t surprise me if some even excrete acetaldehyde under some conditions. Is Lumina really such a change?

gilch 18 Apr 2024 16:40 UTC
2 points
0
in reply to: dirk’s comment on: Open Thread Spring 2024
I didn’t say “cavity”; I said, “tooth decay”. No-one is saying remineralization can repair a chipped, cracked, or caved-in tooth. But this dentist does claim that the decay (caries) can be reversed even after it has penetrated the enamel and reached the dentin, although it takes longer (a year instead of months), by treating the underlying bacterial infection and promoting mineralization. It’s not clear to me if the claim is that a small hole can fill in on its own, but a larger one probably won’t although the necessary dental treatment (filling) in that case will be less invasive if the surrounding decay has been arrested.

I am not claiming to have tested this myself. This is hearsay. But the protocol is cheap to try and the mechanism of action seems scientifically plausible given my background knowledge.

gilch 17 Apr 2024 21:33 UTC
4 points
0
on: Open Thread Spring 2024
PSA: Tooth decay might be reversible! The recent discussion around the Lumina anti-cavity prophylaxis reminded me of a certain dentist’s YouTube channel I’d stumbled upon recently, claiming that tooth decay can be arrested and reversed using widely available over-the-counter dental care products. I remember my dentist from years back telling me that if regular brushing and flossing doesn’t work, and the decay is progressing, then the only treatment option is a filling. I wish I’d known about alternatives back then, because I definitely would have tried that first. Remineralization wouldn’t have helped in the case when I broke a tooth, but I maybe could have avoided all my other fillings. I am very suspicious of random health claims on the Internet, but this one seemed reasonably safe and cheap to try, even if it ultimately doesn’t work.

gilch 16 Apr 2024 16:56 UTC
2 points
0
in reply to: Ligeia’s comment on: The Story of “I Have Been A Good Bing”
Have you tried using a VPN?

gilch 13 Apr 2024 16:59 UTC
2 points
0
in reply to: TAG’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
Yes, agreed (and I endorse the clarification), hence my question about dualism. (If consciousness is not a result of computation, then what is it?)

gilch 12 Apr 2024 22:21 UTC
5 points
0
in reply to: Mart_Korz’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
The Church-Turing thesis gives us the “substrate independence principle”. We could be living in a simulation. In principle, AI could be conscious. In principle, minds could be uploaded. Even granting that there’s such a thing as the superfluous corpuscles, the Universe still has to be computing the wave function.

Then the people made out of “pilot” waves instead of pilot waves and corpuscles would still be just as conscious as AIs or sims or ems could (in principle) be, and they would far outnumber the corpuscle folk. How do you know you’re not one of them? Is this an attachment to dualism, or do you have some other reason? Why do the corpuscles even need to exist?

gilch 12 Apr 2024 0:18 UTC
10 points
0
in reply to: lukehmiles’s comment on: Any evidence or reason to expect a multiverse / Everett branches?

Uncharitable punchline is “if you take pilot wave but keep track of every possible position that any particle could have been (and ignore where they actually were in the actual experiment) then you get many worlds.” Seems like a dumb thing to do to me.

Except I don’t know how you explain quantum computers without tracking that? If you stop tracking, isn’t that just Copenhagen? The “branches” have to exist and interfere with each other and then be “unobserved” to merge them back together.

What does the Elitzur–Vaidman bomb tester look like in Pilot Wave? It makes sense in Many Worlds: you just have to blow up some of them.

gilch 11 Apr 2024 23:56 UTC
2 points
0
in reply to: RHollerith’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
Didn’t Carroll already do that? Is something still missing?

gilch 11 Apr 2024 23:54 UTC
4 points
2
in reply to: Adele Lopez’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
You mean, “Now simply delete the superfluous corpuscles.” We need to keep the waves.

gilch 11 Apr 2024 18:59 UTC
3 points
0
in reply to: habryka’s comment on: The Story of “I Have Been A Good Bing”
Cherry-picking FTW. I wonder if Udio would be any easier than Suno, due to reportedly higher quality and backwards extension, although it wouldn’t have been available at the time.

gilch 11 Apr 2024 2:58 UTC
2 points
0
in reply to: TAG’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
We should not expect any bases not containing conscious observers to be observed, but that’s not the same as saying they’re not equally valid bases. See Everett and Structure, esp. section 7.

gilch 10 Apr 2024 20:52 UTC
2 points
0
in reply to: titotal’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
OK, what exactly is wrong with Sean Carroll’s derivation?

gilch 10 Apr 2024 19:38 UTC
3 points
0
in reply to: lukehmiles’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
I don’t know where you heard that, but the short answer is that no-one knows. There are models of space that curve back in on themselves, and thus have finite extent, even without any kind of hard boundary. But astronomical observations thus far indicate that spacetime is pretty flat, or we’d have seen distortions of scale in the distance. What we know to available observational precision, last I heard indicates that even if the universe does curve in on itself, it must be so slight that the total Universe is at least thousands of times larger (in volume) than the observable part, which is still nowhere near big enough for Tegmark Level I, but that’s a lower bound and it may well be infinite. (There are more complicated models that have topological weirdness that might allow for a finite extent with no boundary and no curvature in observable dimensions that might be smaller.)

I don’t know if it makes any meaningful difference if the Universe is infinite vs “sufficiently large”. As soon as it’s big enough to have all physically realizable initial conditions and histories, why does it matter if they happen once or a googol or infinity times? Maybe there are some counterintuitive anthropic arguments involving Boltzmann Brains. Those seem to pop up in cosmology sometimes.

gilch 10 Apr 2024 18:56 UTC
7 points
0
in reply to: lukehmiles’s comment on: Any evidence or reason to expect a multiverse / Everett branches?
Well, slightly better than wild speculation. We observe broken symmetries in particle physics. This suggests that the corresponding unbroken symmetries existed in the past and could have been broken differently, which would correspond to different (apparent) laws of physics, meaning particles we call “fundamental” might have different properties in different regions of the Cosmos, although this is thought to be far outside our observable universe.

The currently accepted version of the Big Bang theory describes a universe undergoing phase shifts, particularly around the inflationary epoch. This wouldn’t necessarily have happened everywhere at once. In the Eternal Inflation model, in a brief moment near the beginning of the observable universe, space used to be expanding far faster than it is now, but (due to chance) a nucleus of what we’d call “normal” spacetime with a lower energy level occurred and spread as the surrounding higher-energy state collapsed, ending the epoch.

However, the expansion of the inflating state is so rapid, that this collapse wave could never catch up to all of it, meaning the higher-energy state still exists and the wave of collapse to normal spacetime is ongoing far away. Due to chance, we can expect many other lower-energy nucleation events to have occurred (and to continue to occur) inside the inflating region, forming bubbles of different (apparent) physics, some probably corresponding to our own, but most probably not, due to the symmetries breaking in different directions.

Each of these bubbles is effectively an isolated universe, and the collection of all of them constitutes the Tegmark Level II Multiverse.

gilch 9 Apr 2024 19:22 UTC
7 points
0
on: Any evidence or reason to expect a multiverse / Everett branches?
Getting rid of Many Worlds doesn’t get rid of the Multiverse. They pop up in many different ways in cosmology. Max Tegmark elaborated four levels., the simplest of which (Level I) ends up looking like a multiverse if the ordinary universe is sufficiently large.

In the field of astronomy, there’s the concept of a cosmological horizon. There are several kinds of these depending on exactly how they’re defined. That’s why they use the term “observable universe”. Whatever process kicked off the Big Bang obviously created a lot more of it than we can see, and the horizon is expanding over time as light has more time to get to us. What we can see is not all there is.

Our current understanding of physics implies the Bekenstein bound: for any finite region of space, there is a finite amount of information it can contain. Interestingly, this measure increases with surface area, not volume. (If you pack too much mass/energy in a finite volume, you get an event horizon, and if you try to pack in more, it gets bigger.) Therefore, the current cosmological horizon also contains a finite amount of information, and there are a finite number of possible initial conditions for the part of the Universe we can observe, which must eventually repeat if the Cosmos has a larger number of regions than that number, by the pigeonhole principle. We also expect this to be randomized, so any starting condition will be repeated (and many times) if the Cosmos is sufficiently large. Tegmark estimated that there must be a copy of our volume, including a copy of you about $10^{10^{115}}$ meters away, and this also implies the existence of every physically realizable variation of you, which ends up looking like branching timelines.

gilch 9 Apr 2024 18:44 UTC
3 points
0
on: Any evidence or reason to expect a multiverse / Everett branches?
Pilot Wave is just Many Worlds in disguise:
Are Many Worlds & Pilot Wave THE SAME Theory? (youtube.com)

gilch

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