Recent comments in /f/askscience

XtremeGoose t1_j6b37o7 wrote

Reply to comment by Yaver_Mbizi in In the absence of cosmic radiation, would an object placed in space eventually cool to absolute zero? by IHatrMakingUsernames

That's because temperature as it's classically defined has a coordinate asymptote (at 0K). The fix used in quantum thermodynamics is to talk about thermodynamic beta which is the inverse of temperature, where heat flows from a low thermodynamic beta to a higher. That fixes the coordinate issue and you can cross easily from the classically to the quantum.

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Glasnerven t1_j6aykjk wrote

Reply to comment by Ausoge in What does it actually mean to “burn fat” during exercise? by orange-robin

> One thing I find really cool about weight loss is how the mass actually leaves the body. I don't remember the exact process, but ultimately it is mostly excreted via your lungs - all that carbon and oxygen is breathed out as carbon dioxide.

If my memory serves me correctly, when you want to know how many calories a person is burning--and to measure it accurately, instead of just estimating by their level of activity--you do it by measuring how much carbon dioxide they produce. Metabolism is combustion.

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Ungrammaticus t1_j6aviwy wrote

Reply to comment by kibi_zero in Why can an adult’s GI tract expel C. botulinum spores while an infant can’t? by curiousnboredd

Only if you wreck your gut flora enough that you’re also at a high risk of dying from diarrhoea-induced dehydration, or other opportunistic infections. It would have to be very, very bad.

In addition to that, there is the stomach-acid which acts a barrier.

If you’re worried about the effects of antibiotics on your gut biota, you can take probiotics during the course.

But don’t be worried about eating honey, any more than you’d be worried about wearing boots that are too heavy to swim in while it’s raining.

If your doc martens are a drowning risk just because there’s rain, several other very noticeable things have gone exceptionally wrong.

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the-mad-prophet t1_j6avh6l wrote

Reply to can gemstones be melted into a gradient? by Acceptable_Shift_247

Someone already answered really well regarding if the can be melted together. I have a possible idea for an alternative though. While it would not be amethyst and sapphire, there are natural ‘colour change’ gemstones that show a different colour depending on the lighting they are under (incandescent, fluorescent etc.)

A great example is alexandrite which is brain-numbingly expensive. But there is also natural colour-change spinel that changes between purple and blue (for your amethyst and sapphire colours). Spinel isn’t well known, is relatively cheap and has a similar hardness of sapphire, making it really good for everyday wear. It’s often found alongside sapphire in nature.

While alexandrite is typically greed and red, synthetic lab-grown alexandrites can be a blue and purple colour. I’ve seen the blue purple with flame-fusion synthetics (nothing to do with fusing gemstones together). Hydrothermals are much nicer but from memory are closer to green red. Synthetics are a great inexpensive option.

Source: worked in gemstone import industry for many years. I’m biased, but I’d recommend going through a registered jeweller if you want to go the natural gemstone route as buying stones online isn’t always going to get you what you asked for or the quality that you should be getting for your money. I know because I inevitably see these stones when customers bring them in and ask me what they’re worth.

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ArmoredHeart t1_j6auphx wrote

Reply to comment by CrustalTrudger in can gemstones be melted into a gradient? by Acceptable_Shift_247

Would you happen to be knowledgeable about the mechanics of the mineral solids? I was wondering how structurally sound a ring cast or carved from a single mineral (let’s say a quartz) would be.

I only ever did a bachelor’s in Geo and do some jeweling and gem-dealing, so I have an educated guess that it wouldn’t be, due to cleavage planes making it brittle. I’m contrasting it with its chemical twin, glass, which is successfully formed into a variety of shapes—I imagine this because of its vitreous crystal form giving it more flex than minerals with actual geometric crystal forms. I was fairly confident at first, then started considering how fast cooling can mean only tiny crystals get to form, so maybe that would be sound compared to carving a ring out of a gem-quality sample.

I also recalled that jade minerals have been carved by humans for ages without casting or modern tools, so now I’m doubting my guess, or wondering if less-than-gem-quality materials would work better.

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Dbeka_X t1_j6atw1b wrote

Reply to comment by copiouscoper in Has a new animal species evolved since mankind’s existence? by coding_ac

It is only flimsy if used incompletely: Two organisms belong to two different species if they do not reproduce - the keyword would be „reproductive community“. This can be due to genetical /anatomical differences or (!) because they don’t share the same ecological niche.

This definition does not apply to organisms that reproduce non-sexually.

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