I suspect the answer here is yes, and there’ll be a lot more hydrogen and oxygen in the star afterwards… but really I’m posting to see what a proper scientist will say.
Am keen to know if this would pretty much include anything. For example, if I gathered a great enough density of chocolate eclairs in one place, would that become a star?
I believe anything lower from iron will make a star, when enough material added. Of course, one material from iron will give a much smaller lifespan for a star rather than hydrogen only.
I think that an iron ball wouldn’t start a fusion. Might just jump right to a black hole if you added even more iron 🤔
There is a way to find that out. We can use Schwarzschild radius to find the point at which an objects radius crosses the event horizon and thus becomes a black hole; Rs=2GM/c^2^, Rs being the Schwarzschild radius, G being the gravitational constant (6.67xe^-11^), M being the things mass, and c being the speed of light.
Trees grow layers on the outside, just underneath the bark. This is the only part of a tree trunk that is actively growing and is part of the plant’s circulatory system. All the older wood toward the center of the tree is basically only structural support.
There’s a technique called “collaring” used to remove invasive trees, if you cut a shallow, 4 inch tall ring from the bark around eye level, everything above that ring will die, because you’ve severed the circulatory system between the roots and everything above the collar
This is such a great question. I have almost zero knowledge of biology so I can’t offer a meaningful answer. I just want to say this really is a genius question.
Different printers have CMYK primaries with different spectra, so there’s not going to be a generic solution. But in principle, CMY can only create a linear combination of three discrete frequency bands, not a continuous spectrum.
The same will be true of the appearance under monochromatic light: you can only make colors that blend the monochromatic appearance of the primaries. So if none of the three primaries has the desired effect, you can’t create the effect by mixing them.
Studies of gene flow are probably more what you’re looking for, rather than phenotype. I’m 10 minutes from heading out the door so I don’t have time go hunting for links, but if you search for information about haplogroups, molecular clocks, and mitochondrial DNA you’ll be able to find a lot of information about the history of gene flow in humans.
In the newer editions it’s removed. On the older ones there’s no introduction of “impact force”. Maybe it’s just impulse they are talking about. Thanks for taking the time!
I know this is kind of off topic but I wanted to point out that the refrigerant that escapes from air conditioners when they leak or are thrown away, is a bigger contributor to climate change than the electricity they use.
Good point! Freon (CFC-12, with 10800x warming potential of CO2) has thankfully been banned by Montreal Protocol of 1987, and HCFC-22 (5280x) is being phased out. We are using what now, HFC-32 at 2430x? How much refrigerant does an AC contain, about a mole? I’ve been taught that refrigerant should normally never leak throughout the lifetime of the appliance (technicians are even prohibited from “recharging” refrigerant without identifying and fixing the point of the leak first) and that all gas must be recovered after end-of-life, but we can’t be sure that’s really what happens every time.
In that case leaking 1 mole of HFC-32 would be equivalent to… running the 1kW AC for 360 hours?
In my experience with the automotive industry. AC systems leak frequently and it is very common for the leak to be so small that it is not always possible to find the source.
So the majority of the time a fluorescent dye is added to the system and it is recharged with refrigerant to help find the source when it gets low again.
It’s common to have a leak so slow and undetectable that no one notices a system is low on refrigerant until a year later when it is summer again.
Also, auto parts stores sell cans of refrigerant so anybody can just recharge a leaking system, which is often cheaper than actually fixing the leak. So these AC systems are just constantly leaking refrigerant and being recharged.
I wouldn’t be surprised if AC systems in buildings are handled similarly.
Even if a law is made that a failed part must be identified before the system can be recharged, the technician who can’t find a leak is going to just pick a part (randomly or educated guess) to replace if he can’t find the leak.
I won’t comment on the final accuracy, but I will note that this is an extremely roundabout path to your final answer, and some of the intermediate steps are…weird. Most notably, the speculation that every man, woman, and child on the planet might run a 1 kW appliance 24/7/365. This is 7e13 kWh or 70k TWh, about 3x current global energy use (not just electicity) before accounting for efficiency. The equation you cite for radiative forcing, specifically its ln(new/old) term is very non-linear, so you should get a much lower marginal effect from 70k TWh than from 1 kWh.
A simpler approach is to calculate the CO2 required for your 1 kWh AC, i.e.: 1kWh * 3600 kJ/kWh / 0.6 efficiency / 890 kJ/mol = 6.7 mol CO2. Current atmospheric CO2 is 75 Pmol. From that, I get radiative forcing of ln((7.4e16 + 6.7)/7.4e16)/ln(2)3.7 * 4pi*(6.4e6^2). Numpy won’t tell me what ln(74000000000000006.7/74000000000000000). It will tell me the forcing from 10 kWh is ~2.5W, or the same 0.25W/kWh you got. I guess ln is not that nonlinear in the 1+1e-16 to 1+1e-4 range, after all.
0.25W/kWh seems improbably high. 1 kWh is about 0.1 W running 24/365. At 60% efficiency, that’s burning 0.2W of natural gas and implies that the radiative forcing from CO2 is much greater than the energy to produce the CO2 in the first place. I get that the energy source for heating is different from the energy source for electricity, but it feels wrong, even without the 1000 year persistence. I don’t know where the radiative forcing equation came from nor its constraints, so I’m suspicious of its application in this context. There’s a lot of obscenely large numbers interacting with obscenely small numbers, and I don’t know enough to say whether those numbers are accurate enough for the results to be reasonable. Then there’s the question of converting the energy input to temperature change.
Numpy won’t tell me what ln(74000000000000006.7/74000000000000000).
Ran into exactly this problem for individual calculation 😆. Which is also why I multiplied by 8 billion and divided in the end - make the calculator behave. ln is linear enough around 1±epsilon to allow this.
implies that the radiative forcing from CO2 is much greater than the energy to produce the CO2 in the first place
That’s what I wanted to find out and it does appear to look exactly that way. Makes sense in retrospect since the radiative forcing is separate from the energy content of CO2 itself, same way as a greenhouse gets hot for no energy expended on its own.
Numpy won’t tell me what ln(74000000000000006.7/74000000000000000). Ran into exactly this problem for individual calculation
Trouble is that 74000000000000006.7/74000000000000000 ~ 1.000 000 000 000 000 1 and double-float precision is 0.000 000 000 000 000 2. Needs a 96 or 128 bit float. The whole topic of estimating one’s personal contribution to global phenomena is loaded with computer precision risks, which is part of what makes me skeptical of the final result, without looking far more closely than my interest motivates. Like calculating the sea level rise from spitting in the ocean - I believe it happens, but I’m not sure I believe any numerical result.
Your skepticism is excessively cautious 😁. You can work around precision limits perfectly fine as long as you are aware they exist there. Multiplying your epsilon and then dividing later is a legitimate strategy, since every function is linear on a small enough scale! You can even declare that ln(1+x) ~= x and skip the logarithm calculation entirely. Using some random full precision calculator I get:
<span style="color:#323232;">ln(1+x) ~= x
</span><span style="color:#323232;">6.7/74e15 = 9.0540540...e-17
</span>
You are worried about differences in the final answer of less than 1 part in a million! I try to do my example calculations in 3 significant figures, so that’s not even a blip in the intermediate roundoffs.
Your oversimplifying. No offense, but your calculation is a bit of a spherical cow in vacuum.
I am not gonna do the math, but the concept is simple: to cool a small amount of air you must heat a larger amount of air somewhere else. A/C is basically a heater overall, that consumes more “fuel” (whatever is your fuel) than normal, winter heating per identical volume of heated air.
That is why they say it is not great. Regarding the calculations, all co2 based calculations are not really accurate. It depends on the energy source, on the efficiency of energy production, on location of production, of supply chain… CO2 measures for a given product are extreme, inaccurate approximations not really meaningful on large scales. I won’t worry too much. I’d use A/C only when needed, with target temperature between 25 and 28, and you’ve done your part
The nuclear pulse propulsion ship from the novel Footfall.
The technology to produce a spaceship powered by exploding nuclear bombs is fairly basic. It needs to be heavy, and it needs to have massive springs to damper the shock, and thats about it.
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