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MODERATORS
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Thank you for your consideration!

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Any recommendations on good introduction books for kids? Any science or engineering book would be good!

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Basically, my question is the title. If a black hole crosses the Roche limit of another black hole, what happens?

For a hypothetical example, let's say you have a two black holes: one at 5 solar masses and one at 300 solar masses. If the smaller black hole crosses the Roche limit of the larger what happens? Does they simply merge? Would the event horizon of one or both black hole's be geometrically distorted in some way or retain their spherical shape?

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L-methylfolate for example.

Are you supposed to pronounce it as dextro/levo or as a letter?

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Context: I am not a fridgy, I work with electronics. I would love to answer my question by tearing open a dozen different aircon units, but I'm sorely lacking in that department.

Question: Are there some optional components or fancier materials that are simply too expensive to use in the lower end aircons; but are used in the higher efficiency expensive units? The range of COP/EER I see advertised is wild, from 2 to 6 or so.

I already vaguely understand that these things help efficiency:

  • Bigger indoor & outdoor coils with more metal in them (working fluids get returned hotter/colder gives better carnot efficiency)
  • Operating compressor at its optimal power level (I believe they have an efficiency vs power curve with a single peak, so it's better to use a bigger compressor if you need more power output)
  • Inverter control instead of on/off control (most situations, but technically some use cases will have them on par)
  • Choice of refrigerant (but that seems to be controlled in my market, I have not seen many options)

Is there anything else they change? Or is that most of the difference?

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An often repeated statement about any extraterrestrial object is: "if it has liquid water it might suport life". On this assumption a lot of space probes, robots and rovers include the sensors and the instruments the search for traces of past life. This has had high priority in many missions to Mars and it will have high priority also in future missions to the satellites of Jupiter.

Now the thought came to my mind that the ability to support life might not be enough. Life on Earth exists in the most inhospitable places, even in lakes that formed below the polar caps. But the theory is that life evolved in the primordial soup, which was a very favourable environment, only later it spread to inhospitable environments.

To repeat myself, what I am saying is that the ability to support life and the ability to support the birth of life might be two different things. How much different is the question. If the answer is that the difference is strong and life needs a cosy environment in order to arise the assumption it had liquid water therefore it might have had life is moot.

So, how strong is the difference? Is just some liquid water in unknown conditions enough to let life arise, even if it might support existing life?

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Just using a silly example, I'm just curious how pouring water like liquid into another water like liquid can create short lived bubbles

Thanks for your input

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I am trying to understand the limitations and weaknesses of a system of complex human social hierarchical display based on reputation and accolades instead of the accumulation of wealth. Academia is one such example of a hierarchy based on reputation.

What are the weaknesses of such a system, such as failures to account for human adaptation and growth? Where are factors that are not in line with meritorious achievement and the scientific process? What changes could be made to improve the social system of a reputation based hierarchy?

This post is heavily abstract and conceptually framed in layperson terms. Feel free to rephrase and infer meaning. I am thinking about a distant science fiction future when accrued wealth is no longer an adequate form of human hierarchical display, and the benefits, frustrations, and failures of such a system.

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There's been a few probes sent over, and the link lists a lot of "got a few pictures before being crushed by pressure" because the surface is so harsh. If we were to land another probe there, assuming we managed to land right next to where the old ones landed, would there be anything left? Or would the pressure and wind have scoured away any trace?

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Most people know that a microwave works by exciting water molecules, but I'm not interested in the dangers of the high voltage/current of a magnetron. I wonder what might be possible with scrap consumer drivers such as a piezo, speaker drivers, or ultrasonic inducers, preferably at a frequency outside of the core human audible spectrum.

  1. Would an induced vibration in an around 60°C, lightly convective environment, likely significantly increase the evaporation rate of water moisture absorbed within the filament of a spool of consumer grade 3d printing filament such as PLA, PETG, PC, TPU, or Aramid?
  2. Would certain frequencies likely alter performance?
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To which degree in your FOV would the plane reach?

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I had chagas as a kid, and it wreaked havoc on my body. One doc pointed out I probably had some organ scarring. That was over ten years ago. So, as the title, do I need to be on my toes as I get older?

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I'm thinking that hanging still doesn't stress the fiber but possibly makes it stiff and brittle while a gentle motion caused a small wear but keeps the textile flexible. Any material science people in the house?

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Is it just a matter of not being worth it? I see cooling towers releasing what appears to be a ton of steam, pretty high up. If that steam were captured at the top and allowed to condense, wouldn't that result in a ton of water with a lot of gravitational potential energy? That water could then be released and used to power water turbines. Maybe I'm overestimating the amount of water being released as steam, or underestimating how much is needed to spin a water turbine to get a meaningful result, but it seems like wasted energy to me.

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They seam to have a flatness of λ/2 - λ/4 and are quite cheap, 10 bucks for a 25mm diameter one (that 1/5 the price of a normal 25mm secondary elliptical mirror)

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Could they reasonably survive? If so, what would be the effects of such an introduction?

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Whether it be social media use or access to pornography, are there valid studies that have looked into this? I feel like I've only seen anecdotes, or "inappropriate for children", but no evidence, studies, or journals to support this claim.

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