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Sponges, especially large and thick ones, are extremely porous and have an incredibly high surface area. The more surface area there is, the more space bacteria has to grow - especially because a sponge likely has bits of food debris lodged in it to feed them. This also makes it difficult for detergent to fully penetrate every nook and cranny, and a high bacterial load, combined with the large amount of lipids typically present in food, will very rapidly "use up" all available detergent in the sink.

I wouldn't resort to cooking my sponges though - I don't like the idea of broken-down plastics and petrochemicals from synthetic sponges making it onto my plate. Letting a sponge completely dry out between uses is pretty effective at killing germs, and always make sure you use lots of detergent when washing your dishes. And yeah, regularly switch to a new sponge.

That's true. Most hand-and-body soaps are developed without detergents, and wash away bacteria cells rather than kill them - this is because detergents have the same effect on your skin cells as they do on bacteria, and repeated use for cleaning your body would cause injury over time.

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I'll address your questions one at a time.

First, detergents are close to 100% effective at killing germs, but they can only be applied to exposed surfaces - any bacteria that have infected deeper tissue, or are hidden in nooks and crannies, cannot be reached by detergenty water, so other treatment is needed. Detergents cannot be applied internally - see the next part of my response for why. With that said, regular hand-washing is one of the most effective disease-control measures we have.

Second, detergent absolutely does have this effect on human tissue. Your skin cells in particular have evolved to be quite resilient, but detergent can and does kill them - fortunately your skin is made of many layers of cells, so damage is not immediately evident. Your skin also secretes oils to keep it soft and protected, and these oils use up a good amount of detergent before it can get to the cells themselves.
But wash your hands with strong dish soap many times a day, and after a few days you'll develop irritated, dry, cracking skin, with bleeding sores. This is also why the whole tide-pod thing was so dangerous - your internal tissue has not developed the same resilience as your skin has, and eating high-strength detergents can cause serious damage to your digestive tract.

Third, how can bacteria live on soap? Partly because of the reasons I mentioned in the previous paragraph, most body soaps have been developed to not so much kill bacteria and other cells, as dislodge them and allow them to be washed away. This causes minimal damage to your skin, but still cleans it - the bacteria have been washed off, rather than killed. Furthermore, those soaps and detergents that ARE lethal to cells (like dish soap) are only effective in the presence of water. See my original comment for more info there.

Most engines are. Since liquid fuelrd rocket engines don't overheat, running them at less than top power would mean you are taking extra weight in orbit.

Nice, all this make sense and these answers were pretty close to describing in some detail what I was trying to look more into. Thank you!

I was also naively hoping for an undeniable elegant and satisfying practical demonstration of two different coloured lines kissing and boom, new colour, without fakery. I suppose things like the psychological aspect of colour perception will also get in the way to make it that level of satisfying. I haven't tried the computer graphic idea yet, but I'll give it a shot.

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Very interesting. Thank you for the knowledge once again

Correct. The reason for some people being seronegative for autoimmunity can be due to the variation in epitopes, or the specific parts of an antigen that are recognized by the immune system. If the immune system does not recognize the specific epitopes on a self-antigen, it may not produce antibodies against it, resulting in a negative test result. Additionally, the presence of autoantibodies does not always indicate the presence of an autoimmune disorder. Some individuals may produce autoantibodies as a result of normal immune system function, and they may not develop any clinical symptoms. Therefore, it is often necessary to confirm a diagnosis of an autoimmune disorder through other means, such as a thorough medical history, physical examination, and additional testing.

Isn't that basically the definition of a booger?
Snot-based Jello.

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But it’s so interesting that some go and some stay. Is it because our cells can only hold so much “data”?

Wait 1 more implication then, could that explain the reason for some people being seronegative for autoimmunity?

Antigen-specific antibodies are produced by the immune system in response to the presence of a specific antigen, such as a virus or bacteria. The production of antibodies is a natural process that helps the body to defend itself against infection and disease. Some of the antibodies produced in response to an antigen will remain in the body for a long time, providing ongoing protection against future exposures to the same antigen. Other antibodies may not persist for as long and may be cleared from the body over time. The length of time that an antibody remains in the body can depend on a variety of factors, including the specific characteristics of the antigen and the immune system of the individual.

Are you imagining the system that used L/R and up/down as the two channels being a rectangular groove? If it was still a V-groove, you wouldn't have the problem described in your first paragraph, but I agree that the system that is actually used is better, for the reason described in your second paragraph.

Also antigen-specific antibodies, how come some stay and how come some go?

Light wavelength can be as big as the empire state ( radio) or as small as a Planck 's length (lethal radiation) so there is a big "not impressive" margin.

Still very impressive precision in nanometers but we gave way smaller things (chip manufacturering).

For the past 10 billion years a linear expansion was a pretty decent approximation. The early universe slowed its expansion, which makes the relative reach of the ant even larger (or, equivalently, the early recession speeds were larger).

The Hubble rate is still decreasing. It's expected to approach a constant in the future. I covered that in the second paragraph:

> In the distant future, in a universe completely dominated by dark energy, your statement will be right.

The ant on a rubberband example does not work for the universe. Even if the Hubble constant was constant with time, the universe expands exponentially, not linearly (so the “universe” rubberband length goes 1,2,4,8; not 1,2,3,4). An ant on an exponentially growing rubberband cannot reach everywhere.

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