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Cake day: July 3rd, 2023

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  • Seriously. Southern CA alone is 4-5x the population of all of Norway, and that region often has 3-4 taco shops per block when it’s allowed by zoning.

    Edit: the USA has 75,000 Mexican restaurants. That means that there are only 73 people in Norway for every Mexican restaurant in the United States.

    The average restaurant in the USA serves 100 people per day. That means that, on average, US Mexican restaurants serve more people daily than the entire population of Norway.




  • It certainly has the potential to be. Remember most of the costs related to fission are safety measures, plant decommissioning, and waste disposal. If we merely had to operate the reactor without concern for those issues, fission would be incredibly cheap. The fuel costs and basic technical requirements to operate a reactor are trivial in comparison.

    Fusion produced 4x more energy per mass of fuel compared to fission, isn’t at risk of meltdown, and has the potential to produce negligible radioactive byproducts. In addition, it outputs helium which is an important and finite strategic resource.

    Even if the cost of fuel goes up dramatically compared to uranium reactors, it might still outperform nuclear in a big way. However, sourcing He-3 from the moon might be a lot cheaper than you think. My day job is related to space resource utilization. Transporting resources off the surface of the moon could be quite economical once we reach a sufficient level of development.


  • The usual joke is that fusion is always “30 years away”, not 10. The reason is that fusion projects have historically faced an issue where funding is chronically below predictions

    However, this past decade is seeing a number of promising changes that make fusion seem much closer than it ever has. Lawrence Livermore managed to produce net energy gain in a fusion reaction for the first time. Fusion startups are receiving historical levels of VC funding. ITER is expected to produce as much as ten times as much energy as used to start the reaction. The rise of private space infrastructure is making helium-3 mining on the moon more possible than ever before.




  • Search the literature for thermal stratification. There are many contexts where it is used outside of lakes and other large bodies of water, many of which do not consist of three distinct layers. Hell, the paper I cited SPECIFICALLY refers to the temperature gradient in the microwaved glass as “stratification”.

    If you can’t understand the use of a term outside your specific area of expertise then thats honestly a you problem and that’s all I can say on that.

    If the heating methods were as similar as you say, there wouldn’t be hundreds of publications accepted to various journals across the past two decades investigating the problem where microwaves produce a strong temperature gradient between the top and bottom of a body of liquid. It’s a well known process control problem.


  • That’s not really showing temperature stratification which is a more extreme separation of temperature from surface

    I think the definition you are using is far too restrictive, in many contexts temperature stratification simply refers to a situation where you get temperature gradients across a fluid with the warmer fluid gathered near the top of the body. For example, in a factory you will often have “destratification” fans operating because warm air from equipment rising to the ceiling results in a temperature gradient from floor the ceiling.

    It is not a phenomena exclusive to surface heating.

    That’s just showing that the hottest atoms gather to the top, which btw, proves Convection currents.

    Yes. My point was not to establish that convection is magically absent from fluids in microwaves, but to establish that it differs significantly from stovetop heating. Convection currents in stovetop heating create a strong stirring action that produces a substantially uniform temperature. Microwaves do not create the same stirring action and this produce a significant nonuniform temperature gradient.

    The modified glass is just diverting the hotpots to the bottom to make the convection less “unusual”.

    Clearly. They make the heating more akin to a stovetop, which is really the point here.

    They aren’t claiming that convection doesn’t accrue, only that it’s “unusual convection” resulting in less even heating like that of thermal stratification, not literal thermal stratification where the layers have separate convection currents that prevent mixing all together.

    Once again, you are using a definition of thermal stratification that is far too specific. However, arguing over it is really just being pedantic because the core point at issue here is whether or not heating a cup in a microwave or a stovetop produce the same final product. They do not unless you apply some mechanical agitation to mix it up.


  • I’m well aware of temperature stratification. It doesn’t happen in a microwave.

    It empirically does. We can argue about the theory all day but the research says microwaves produce stratified temperature gradients when heating liquids. However, I’d point out that, in atmosphere, when we have localized hot spots the warm air can effectively travel in bubbles without significant mixing for quite some distance. There seems to be a similar phenomena at work when microwaving liquids.

    See the screenshot below.

    I pulled this from “Multiphysics analysis for unusual heat convection in microwave heating liquid” published in 2020 in AIP Advances.

    Relevant excerpts:

    “ Usually, the fluidity of liquids is considered to make the temperature field uniform, when it is heated, because of the heat convection, but there is something different when microwave heating. The temperature of the top is always the highest in the liquid when heated by microwaves.”

    “ The experimental results show that when the modified glass cup with 7 cm metal coating is used to heat water in a microwave oven, the temperature difference between the upper and lower parts of the water is reduced from 7.8 °C to 0.5 °C.”

    “According to the feedback from Midea (microwave appliance makers), when users use the microwave oven to heat liquids such as milk or water, the temperature at the top of the liquid will be significantly higher than the temperature at the bottom.”







  • Forcing kids to bring coats is weird to me

    Maybe it’s different elsewhere, but I was born into a relatively cold+wet climate and moved to San Diego in elementary school. I didn’t bring a coat because it made me hot, I was acclimated to colder weather, and I didn’t want to carry it around.

    They refused to let me go outside for recess for weeks because I didn’t bring a coat and refused to wear one from the lost and found. Finally, one day, they sent me to the principal’s office and called my mom in for a chat to discuss my misbehaving.

    My mom’s response was, “You called me in from work for THIS?! If he’s not cold, he’s not cold! He has warm clothing at home. He’s capable of deciding whether or not he would be more comfortable with a jacket on. Let him go outside and leave me alone”



  • Energy storage of solar is promising to be cheaper than nuclear

    Nuclear powerplants are very, very expensive when you amortize the commissioning and decommissioning costs into the lifetime expenses. There have been repeated attempts to encourage fission adoption over the last 20 years and almost no new plants are being made because the economics just don’t work.



  • The reason fusion is always 30 years away is because that statement is always accompanied with the subtext of 30 years at the current funding rate. Funding consistently decreased for decades as optimism in the tech fades.

    However, this decade will be marked with a number of breakthroughs. Last year we achieved the first net energy gain from fusion ever, there are a number of fairly well funded startups with very promising tech, and ITER will be the closest we have ever gotten to a real working fusion plant with (hopefully) large scale net energy

    Now is precisely the right the time to increase funding to fusion to push us over the hump into usable power production