Recent comments in /f/askscience

Mediocrasleep t1_j9qckpi wrote

Reply to comment by FineLetMeSayIt in How can Doctors tell if one of your kidneys isn't working? by FineLetMeSayIt

If one kidney suddenly fails, the other kidney usually cannot compensate in time, so labs will show abnormalities. Though even with one healthy kidney, some labs are still abnormal.

But yes, a lot of times, the injuried to the kidneys are happening at the same time (hypotension, drug reactions)

Kidneys are more sensitive to damages and are smaller than other organs as well. On average.

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enderxzebulun t1_j9qcacy wrote

Reply to comment by Holgrin in What does it mean for light to be an excitation in the electromagnetic field? by Ethan-Wakefield

>Then, after graduation, I read this book because I thought it would just be good general knowledge: > >https://press.princeton.edu/books/hardcover/9780691135045/physics-and-technology-for-future-presidents

Just ordered this, thanks for the recommendation. FYI: coupon code PUP30 applies a 30% discount.

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FineLetMeSayIt OP t1_j9qbfjw wrote

Reply to comment by lascivious_boasts in How can Doctors tell if one of your kidneys isn't working? by FineLetMeSayIt

Thank you for such a wonderfully detailed response! I guess barring an anomaly on your tests, doctors would never think to look for single sided kidney failure. I don't know enough about kidney diseases, but I thought about this because of a coworker/acquaintance who currently has to undergo dialysis. In laymen's logic, it would seem unlikely BOTH of her kidneys failed at the same time. Which means at some point one kidney was doing the job of two, but nobody noticed.

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fastspinecho t1_j9q9gwm wrote

Reply to What will be the environmental impact of de-orbiting 42,000 Starlink satellites every five years? (Explanation in post) by OvidPerl

They aren't planning to use 42,000 Starlink 2 satellites.

The current plan is to deploy 10K to 30K satellites. They don't think they will actually need 40K.

Furthermore, the majority of their satellites are first generation, which weigh only 250 kg. They are only authorized to launch 7000 Starlink 2s. Starlink 2 satellites are more capable, so every Starlink 2 they launch will reduce the total number needed.

SpaceX launches 10 or so Falcon 9s a month. Each one can carry 60 of the smaller satellites, but only a handful of the Starlink 2. I don't think it's feasible for them to launch an average of 23 Starlink 2 satellites a day, even after switching to their bigger Starship rocket. And what comes down must go up.

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zoicyte t1_j9q8opb wrote

Reply to comment by morningcoffee1 in What will be the environmental impact of de-orbiting 42,000 Starlink satellites every five years? (Explanation in post) by OvidPerl

here's a real answer:

Scientists estimate that about 48.5 tons (44 tonnes or 44,000 kilograms) of meteoritic material falls on the Earth each day.

don't be too worried about the 23 500-lb satellites that will also vaporize alongside the 44 tons of space rocks that already do the exact same thing.

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numatter t1_j9q6jl3 wrote

Reply to comment by Ethan-Wakefield in What does it mean for light to be an excitation in the electromagnetic field? by Ethan-Wakefield

A stationary magnet has a static (fixed) "field" around it. In a perfect vaccuum, it doesnt emit any photons, because theres nothing interacting with it that would cause it to become "excited" and emit EM radiation.

A rotating magnet, regardless of being near a black hole, produces a dynamic (changing) magnetic field, and since those interactions contain information (quanta), we're all familiar with something heating up - which are photons in a spectrum we can't see with the human eye. Given enough time, in theory, the entire mass of the magnet would eventually be irradiated outward as light energy.

Lenz's law provides details on extracting energy from this very thing. You can spin the magnet around an electrically conductive material, like an iron nail. The nail becomes excited by the photons, and electrons start moving around (electricity). Alternatively, you can shake or spin the iron nail around a permanent magnet and produce the same thing via induction.

Your question in regards to a black hole is quite intriguing. Yes, a rotating magnet can act as a broadcast antenna, but its not very efficient to do so because magnets and all ferromagnetic materials have the uncanny ability of picking up and amplifying extra signal "noise" (ingress). What's fascinating to think about, is that a magnet in orbital motion around a black hole would indeed act as a "pickup" in exactly the same way a guitar pickup works. All these frequencies being thrown around together would be picked up and turned into the electrical signal version of the EMFs, then be induced back into the magnet in a Jimi Hendrix-esque feedback loop.

So when you're saying a "magnet" is spinning around a black hole, don't imagine a handheld rectangle magnet. Imagine instead that it's a magnetar... I mean... I can't even fathom the magnetic power of one of these alone, much less being involved in a stellar dance off with the energy source of a black hole. If something like a pulsar/magnetar were to be energetically involved with each other, theoretically you could place the magnetar in an energy jet stream of the black hole, and it would emit a "fucking huge" broadcast signal of their blended frequencies... may I say, "spacetime modulation?" Hmm...

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Mediocrasleep t1_j9q65al wrote

Reply to How can Doctors tell if one of your kidneys isn't working? by FineLetMeSayIt

Short of imagining, we do not know which kidney is failing. We can see the overall renal health. If it declines, it will prompt some imagining studies (ie. US, CT).

Why no duplicate? Every organ consumes energy. Imagine if your trunk of your body was twice as big… you need to increase caloric intake and it would make you less mobile. The disadvantage > advantage

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