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Cake day: July 5th, 2024

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  • Yes, of course, there is financing and everything else. I was getting a bit deeper:

    If you have to spend 100 joules building a power plant, it better give back more than 100 joules during its lifetime - otherwise it was never worth it to build. That isn’t strictly true, there are special purposes, but certainly as a grid-scale energy deployment you would need - at a bare minimum - for each plant to pay for itself in terms of energy investment.

    The dollars follow from that physical reality.

    The first hurdle for fusion to clear is that the reaction outputs more energy than it needs to sustained. This would be a great academic success, and not much more.

    The second hurdle is that it outputs enough energy such that it exceeds the sustainment energy even after accounting for capture losses (e.g. from neutrons, turbine efficiency, etc.) and production efficiencies (lasers need more energy input than they impart to the reaction chamber, magnets need cooling, etc.).

    The third hurdle is that over the lifetime of a plant, it produces enough excess energy to build itself and pay the embodied costs of all maintenance and operations work. If the reaction is technically energy positive, but you need to replace the containment vessel every 48 hours due to neutron embrittlement, then the plant better be productive enough to pay for refining all that extra steel.

    The fourth hurdle is then that it produces more excess energy per unit of invested energy than any other form of power generation - at which point we’d never build solar panels again.

    These final hurdles are in no way guaranteed to be cleared. Artificial fusion needs to be orders of magnitude denser than natural fusion (Stars) to make any sense… a fusion power plant the size of Earth’s moon, with the same power density as the Sun, could only power around 1 million US homes.



  • Economical energy production, sure, not any energy production. There is a reason we no longer burn wood to heat public baths.

    I realize the science marketing of fusion over the past 60 years has been ‘unlimited free energy’, but that isn’t quite accurate.

    Fusion (well, at least protium/deuterium) would be ‘unlimited’ in the sense that the fuel needed is essentially inexhaustible. Tens of thousands of years of worldwide energy demand in the top few inches of the ocean.

    However that ‘free’ part is the killer; fusion is very expensive per unit of energy output. For one, protium/deuterium fusion is incredibly ‘innefficient’, most of the energy is released as high-energy neutrons which generates radioactive waste, damages the containment vessel, and has a low conversion efficiency to electricity. More exotic forms of fusion ameliorate this downside to a degree, but require rarer fuels (hurting the ‘unlimited’ value proposition) and require more extreme conditions to sustain, further increasing the per-unit cost of energy.

    Think of it this way, a fusion plant has an embodied cost of the energy required to make all the stuff that comprises the plant, let’s call that C. It also has an operating cost, in both human effort and energy input, let’s call that O. Lastly it has a lifetime, let’s call that L. Finally, it has an average energy output, let’s call that E.

    For fusion to make economical sense, the following statement must be true:

    (E-O)*L - C > 0.

    In other words, it isn’t sufficient that the reaction returns more energy than it requires to sustainT, it must also return enough excess energy that it ‘pays’ for the humans to maintain the plant, maintanence for the plant, and the initial building of the plant (at a minimum). If the above statement exactly equals zero, then the plant doesn’t actually given any usable energy - it only pays for itself.

    This is hardly the most sophisticated analysis, I encourage you to look more into the economics of fusion if you are interested, but it gets to the heart of the matter. Fusion can be free, unlimited, and economically worthless all at the same time.


  • skibidi@lemmy.worldtoScience Memes@mander.xyzPhD ain't no MD
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    11 months ago

    Completely correct. There is also a (much rather in the US) ScD degree - Doctor of science.

    In the US, it is often identical to a PhD. If your institution offers it, you just check a box at the end of your program on whether you want a PhD or ScD. In Europe, an ScD is a higher degree than a PhD and requires some extra work to obtain.


  • Just jumping in to say that red soils are not very fertile. They are nutrient-poor in the necessary macro-nutrients (nitrogen, potassium, and phosphorus) and have a very poor ability to retain water. They are very rocky - little organic matter content - which limits both water retention and cationic exchange capacity (affecting N+ and K+ bioavailability), and tend to be acidic.

    Cultivation is possible, but it requires large amounts of fertilizers and soil conditioning agents (liming to raise pH and add calcium, addition of organic matter). In effect, recreating an artificial soil that is closer in nutrient availability to the black soils present in the world’s most fertile regions (which today are also heavily fertilized).



  • No, not even close.

    I’ve used Unix systems for years at work, and have dual-booted windows with various flavors of Linux at home for just as long. When I just need something to work, particularly something new or after a stressful day at work, I just use windows.

    Why? Because it will just work. Maybe it won’t work precisely how I want it to, maybe it will send all my data to Bill’s push notifications, but it will run. In the rare case it doesn’t, a quick google will fix it.

    Compare that to Linux, where most things will work most of the time. And when they don’t, you get to hunt through GitHub issues off-the-clock like a peasant, wading through comments from people with entirely different configurations and ‘dunno it works for me’.

    Linux is for tinkerers, and for people who want a Unix shell and can’t afford a Mac, it has a long way to go to be more than that.



  • The war for Arrakis is the classic tale of a small number of colonizers against a larger, motivated, native population. The Harrkonens drastically underestimate the total number of Fremen, and try to fight stand-up battles while the Fremen simply ambush less protected targets. I thought this came across fine in the movie.

    The more problematic undertone come directly from Frank Herbert, who had this theory that military prowess only comes from hardship (that’s why the Sardaukar are so tough - because the prison planet they are trained on is so harsh), and the Fremen are nigh-invincible fighters because Arrakis is so hard to survive on. This is a misconception that repeats across earlier anthropological study (e.g. ancient Sparta) and is closely tied to the ‘Noble Savage’ trope.

    Also, there never was a fight against the ‘resources of the entire empire’, Paul and the Fremen fought and defeated the Harkonnens in months-long (movie) or years-long (book) guerilla campaign aimed at lowering spice production. Eventually the Emperor brought his personal forces planetside to restore order. Detachments from the other houses remained in orbit and were not permitted to make planetfall. This is when the Fremen play their trump card of surprise worm attack.