Ngl I have mixed aqua regia to clean out my pestle and mortar in a lab course once. Shit went from uncleanable to clean really quick. H_2O_2 + conc. HCl is sufficient for most extreme cleaning needs tho.
That makes sense, thanks, since our threshold for co2 is less than 0.5%.
I may have worded my question poorly; I’m more asking why low oxygen is a problem vs low nitrogen. In retrospect, my climate focus may be distracting. It was what made me wonder about this in the first place, but the medical and scuba points are much more relevant. That has little to do with co2 (I think?) and more to do with the relative compounds in our air.
I’m still confused why we hear about oxygen but never nitrogen. Another example: when we look for habitable planets, the focus is ‘oxygen rich atmosphere’, but not ‘nitrogen rich’.
Maybe nitrogen could be replaced with other gases, but we need oxygen in our lungs and bloodstream to survive. So maybe it’s more important for our survival?
So from what I understand, we need a rather precise amount of oxygen plus a large amount of an inert gas – pretty much any inert gas, barring a few that have narcotic effects. So nitrogen isn’t special, except that it’s inert and doesn’t get us high.
But I’m also curious whether the reactive gas in low quantities (oxygen) can also be replaced. I’m not a chemist, and this is fascinating. I’ll keep reading.
I’m not a biologist, doctor, or chemist, but my guess is “no.” We have evolved to use oxygen to create energy within our cells, not some other gas.
I would hazard an additional guess that it’s not a simple matter to just swap out the oxygen molecules for something else. Carbon monoxide binds better and more readily to our cells, yet that mixture would asphyxiate you.
We don’t need a precise amount of oxygen - we can survive in a fairly wide range. Think about living in the mountains vs by the ocean.
Nitrogen gets us absolutely high. Balls to the wall high. It’s why gas narcosis used to be called nitrogen narcosis. Also known as the “rapture of the deep”.
Also, oxygen gets you high. Also, oxygen kills you, but that’s another matter.
As someone else pointed out, nitrogen is non-reactive. Almost any gas would work, as long as it was plentiful enough to maintain the necessary air pressure, and non-reactive. You don’t need nitrogen to live; you just need oxygen. Just, not so much that you get acute oxygen toxicity, which mainly happens with pure oxygen at regular atmospheric pressure for extended periods of time. There are even applications where pure oxygen is administered to people, usually at lower than atmospheric pressure.
Nitrogen is a filler gas. It’s there to take up space and keep the air molecules bouncing around at the appropriate pressure. (Or perhaps it would be more accurate to say our lungs require a certain pressure because this is where we evolved; that pressure happens to be maintained mostly by nitrogen.)
We aren’t exploring other planets in person yet, but if we were, we’d need to filter out all the bad shit in the air, keep the oxygen, and maintain the normal pressure. If we were lucky enough to encounter an atmosphere with oxygen, a non-reactive filler gas, and no toxins, we might be able to just breathe it; or to breathe it after compressing it to the appropriate pressure. Nitrogen wouldn’t need to be there at all.
The confusing thing about the scuba application is that nitrogen isn’t in the mix because you need the nitrogen. It’s there because it reduces the pressure of toxic gases to a threshhold you can survive.
Thank you for your detailed response. That explains things very well. I don’t know a lot about chemistry, but is oxygen specifically required for cell metabolism or could that be replaced with a similarly reactive gas, too?
We’re pretty hyper-specialized to use it, but there are organisms on earth that don’t need it and in fact find oxygen deadly; they are called anaerobic. They still need chemical energy, it’s just not provided by oxygen. (As I was looking this up I discovered there’s even a creature in the animal kingdom that doesn’t breathe oxygen.) Some gases, like carbon monoxide, will actually participate in gas exchange in your lungs and react with your body chemistry, but in a way that rapidly breaks down cell functioning.
So, yes, there are definitely other forms of biochemistry that can process non-oxygenated environments and extract energy from them, just not us, not by a long shot.
There is a fan running and then the actual microwave itself. If you lower the power setting, you can hear the fan stay on consistently but hear the microwave shut off and on. If the power is at 100%, the microwave runs the entire time.
A few microwaves don’t do that because they’re able to continuously run the magnetron at less than full power by using an inverter instead of a transformer.
Your question made me realize I had never thought about this at all so I spent some time searching. If I am understanding this article correctly it essentially boils down to the factors that would cause rotational symmetry at a smaller scale ie spinning sand on a plate apply at the galaxy scale as well.
There’s several factors at play here. An athletic heart is not only more efficient down to the conductance of the cardiac tissue, but it also has a larger stroke volume. With those 120 bpm each beat could be pumping 40cc of blood while in the other heart each beat might only be able to pump 30cc. This is because an athletic heart is able to more fully contract to squeeze out all of the internal volume. Think of the conductance of the heart as a snowy hillside. The first time you take a sled down the hill the snow hasn’t been compacted to make a path. The more often you take your sled down that path, the more compacted it gets and the faster you and your sled will go down the hill the next time. Plus I haven’t even mentioned blood pressure decreasing in an athlete due angiogenesis and dilation of already present veins and arteries.
So to summarize, it’s not just bpm that need to be accounted for here. You also have to consider:
conductance lowering the cardiac impulse threshold
I think it’s probably more than confirmation bias in this case. Twins generally have a lot of shared experiences and environment. It’s not surprising that they would more dialed in to how their sibling thinks/responds.
But quantum entanglement has nothing to do with it.
I think their point was that there isn’t anything humans could do during the night. Stars might give some light, but without a full moon you really can’t do anything at night without lights.
i mean yeah, but even then starlight is basically fuck all. The moon overpowers those, it just makes the sky look pretty. That’s it.
Cloud cover would be primarily lit by moonlit. And even then, moon light is very dim. Just look at early moon light towers used to light up residential areas early in the electrification period.
It’s literally the difference between being in your home, at night, and you can’t see shit. Vs you can just barely make out where things are, and navigate properly.
Also semantic point, light pollution is not “dark” that’s why you can’t see any stars. Ever looked at a highway lit with LEDs recently? They have tons of light pollution that can be seen as what’s referred to as “sky glow” My point here being, when you go outside in a light polluted area at night, it’s literally not dark.
It does, but as more air drops down, the pressure increases. This pressure then starts to push back against the air above it. Which is why we have atmospheric pressure at the surface, but that goes down to pretty much 0 in space.
Even in low earth orbit there are still some particles, which causes satellites and such to slow down, requiring them to fire some thrusters every once in a while.
There’s increasing evidence that it is lack of exposure to some allergens which causes problems. Current advice is to eat peanuts during pregnancy and to introduce peanut butter to baby diets early to reduce the risk of peanut allergy.
So you’re more likely to be reducing the risk. But there’s a lot we don’t properly understand yet, of course.
There had been long-standing advice to avoid foods that can trigger allergies during early childhood. At one point, families were once told to avoid peanut until their child was three years old.
However, evidence over the last 15 years has turned that on its head.
Instead, eating peanut while the immune system is still developing - and learning to recognise friend from foe - can reduce allergic reactions, experts say.
A species of fig (Ficus, family Moraceae) from the Transvaal of South Africa was determined to have roots reaching at least 122 meters - source, google fu
Depends how you’re using “why”. In Russian, they actually have two words for why, one of which implies teleology, and one which doesn’t, and merely requests some explanation for a phenomenon. I wish we had that in English.
In this case, it’s such a general question you can’t do much better, but you could, for example, talk about why oxygen-carrying proteins pretty much always incorporate an ion of something, in a merely cause-and-effect way. (And I actually don’t know the answer to that one)
The answer to the question, “How did this evolve?”, is the same as the answer to a non-teleological “why”. People just need to learn to use “how” because “why” is such a loaded word.
When using “how” in this sense and “why” in the non-teleological sense, they have the exact same meaning (at least to my ear), but then the “how” version isn’t ambiguous.
If I say to myself, “How did this evolve?”, the question feels good. It feels clear, and my mind leaps into thinking about the function of the mineral in the body and the chain of evolutionary steps that could have caused it.
If I say to myself “Why did this evolve?”, I just can’t get the teleology sense of the word out of my head. If someone didn’t want a teleological answer, why did they say “why” when “how” is clearly better? So I assume they mean why.
I feel like even if I answered their question, the next one would be, “Yeah, but why?” Making me feel like I wasted my time explaining the “how”.
That’s might be an option too, I guess, but in some situations it’s a different question. If I make a mistake and you ask “how”, you might just get more details. If you ask “why” I might respond with “I was tired”, which doesn’t really imply teleology. As I understand it почему would be more specific to cause rather than just means, but then again my Russian is pretty basic. The word “how” would be как, and it even works as an intensifier the same way.
Animals whose biology that used the metals reproduced more successfully is the explanation. It could longer lives, better reproductive outcomes, or a ton of other reasons but it all comes down to reproduction.
Well, genes, if we want to get really technical. Otherwise you can find counterexamples where genes are detrimental to the organism, but manage to spread anyway do to some quirk.
Generally they don’t impact the reproduction rate enough.
Let’s take reproductive cycles as an example of there being no single benefit or negative. Some species reproduce in mass quantities and that works for them, while others are slower. The fast one having genes that slow reproduction would probably die out because their adaptation of mass reproduction is what keeps them around. A slower reproducing species won’t necessarily benefit from higher rates as they might overpopulate their range. So what looks like a detriment could just be a thing that neither benefits nor is a detriment depending on the complex context of the species and where they live.
And sometimes detriment are offset by other benefits, like sickle cell anemia having some terrible outcomes but it also protects against malaria so in the context of somewhere with a high rate of malaria it is beneficial to survive to a reproductive age, which would explain it sticking around.
Ah, so you haven’t heard about this thing. It’s not really lucky 10,000 territory, but it’s still cool.
There are situations, where in sexually reproducing organisms, an unambiguously bad gene can spread through the population, just by ensuring it’s more likely to appear in the next generation. As long as it’s not so bad it kills the species off, you’re still likely to observe it a lot in a future population. We’ve actually harnessed this idea technologically, with genetically modified mosquitoes that crash their local population by skewing all offspring malewards.
That is one example of ‘not detrimental enough to impact reproduction’ which I meant in the context of a population and not an individual, but I guess that my wording wasn’t clear enough.
Theoretical biologist here. I’m going to push back on that just a bit. I think that you might have mentioned Selfish Gene, too. That was not the best book even at the time of publication (most biologists had a number of problems with it oversimplifying in a way that’s probably similar to what anthropologists think about Guns Germs and Steel). It also has been getting worse the more we learn.
Evolution acts on the phenotype, not the genotype. It affects the gene makeup of the population through differential reproduction rates. “Fitness” can be measured as a value relative to the rest of the population specifically by using the number of offspring. So what I’m saying here is that all factors that affect phenotype, whether genes or other factors, affect evolution.
So, of course genes are important. But you have epigenetic factors, too. link here You also have extensive non-coding regions that regulate transcription. You have rna editing. And so on.
If you’re interested, I would highly recommend a book called How Life Works by Phillip Ball. It was just published in November and is an outstanding summary of how much our understanding of life has evolved (heh) in the last 20 years or so.
Well, you would know a lot better. And thanks for the reading recommendation.
What are your thoughts on viruses as a form of life? Asking what natural selection is in exact terms is pretty closely related to asking what life is, since life is probably some subset of things that can do natural selection.
Personally, I do think of viruses as a form of life, and although it’s not universally held by any means, I think there’s a growing consensus around the idea.
That’s probably as minimalistic as I would go, though. I mean, you can make a similar argument to some extent about prions, but prions are too close to being “just chemistry” for me.
Viruses on the other hand cooperate and compete in complex ecosystems, which in my opinion magnifies the complexity of a virus as an element of a complex adaptive system. They don’t have a metabolism as such (which is why so many don’t consider them living), but their ability to conduct theft of resources of more complex and obviously living systems makes me push them to group of living things.
One of the nearest things about biology is that there’s always an exception to the rules and examples, and the simplifications we make when teaching bio 101 are really best learned as rules of thumb. Things like what a “gene” really is, the operation of selection, and even what constitutes a “species” can lead to some really interesting discussions.
A few fields are a bit like that. I remember my chemistry teacher in high school saying something similar.
As mostly a math person, it kind of bugs me. There definitely is one set of rules that a field obeys, and while it’s usually necessary to simplify I’d really like to know how not to. Sure, water is mostly incompressible, but it’s not exactly so, and that’s how sound works and can translate to other mediums. And then once you get down to small scales, high energies or low pressures you start seeing the individual water molecules being relevant and doing all kinds of different things. Those factors were always there, even if they weren’t relevant.
Sorry, maybe that’s a bit of a rant, but all that to say I’m sure you can find a consensus on these questions eventually.
We learned 9.82 m/^2. But in the classes I have as an engineering student we use 10 m/s^2. And I wish I was kidding when I say it’s because it easier to do the math in your head. Well obviously for safety critical stuff we use the current value for wherever the math problem is located at
Going to guess civil. I work on space systems and we don’t have one number. We have the g0 value, which is standard gravity out to some precision, but gravity matters enough we don’t even use point mass gravity, we use one of the nonspherical earth gravity models. It matters because orbits.
Interesting that I learned 32.2 ft/s, but only 9.8 m/s - one less significant figure, but only a factor of two in precision (32.2 vs 32 = .6%; 9.81 vs 9.8 is only 0.1%). Here's the fun part - as a practicing engineer for three decades, both in aerospace and in industry, it's exceedingly rare that precision of 0.1% will lead to a better result. Now, people doing physics and high-accuracy detection based on physical parameters really do use that kind of precision and it matters. But for almost every physical object and mechanism in ordinary life, refining to better than 1% is almost always wasted effort.
Being off by 10/9.81x is usually less than the amount that non-modeled conditions will affect the design of a component. Thermal changes, bolt tensions, humidity, temperature, material imperfections, and input variance all conspire to invalidate my careful calculations. Finding the answer to 4 decimal places is nice, but being about to get an answer within 5% or so in your head, quickly, and on site where a solution is needed quickly makes you look like a genius.
I gotta say, that explanations sounds way better than shrugging and saying “close enough”. But then again our teachers usually say “fanden være med det” meaning “devil be with that” actually meaning “Fu*k it” when it comes to those small deviations
I believe there have been multiple sci-fi stories written about such concepts. It would go to assume that any civilization still around in 10^43 years from now will have no choice but to live around black holes while harnessing their rotational energy. My current favorite series, Xeelee Sequence by Stephen Baxter, explores some possible endings of life in the long-term life cycle of the universe. There is also the final book of the Three Body Problem, which if I remember correctly, shows civilizations in pocket universes around black holes.
There is a YouTube video you may want to watch by Isaac Arthur. It mentions the possibility of combining black holes to elongate their life, and I won’t spoil the final answer for you. But like always, entropy prevails.
Dick Tracy’s communicator watch actually seems pretty shitty by today’s standards. His didn’t have a high def LCD screen in it.
Star Trek’s PADD also seems obsolete by real world standards. Those were just e-readers. A tablet is an entire computer, and a smartphone is an even smaller, pocket size computer. There are even phones and devices that connect to phones that do tricorder like scanning of vital signs, the atmosphere, even analyzing the elements that make up an object through spectrographic analysis. Meaning we have the ability to combine the ship computer, a PADD and a tricorder into one device.
Well, the Tricorder had very advanced scanning capabilities. We can’t diagnose and cure cancer with a handheld device yet, but I did get some viral and bacterial tests done in a manner of moments by some desktop lab equipment the other week, so we’re definitely getting there.
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