It's true my abiding thought after reading the book was what about nuclear weapons. The great powers would absolutely use their nukes if in danger of being overrun, and I think long before that, in a total war.
This does not scale, due to square/cube law (the energy is generated in a volume, but has to leave via surface -> the energy evacuated per surface area has to grow)
It scales, because the surface of the network of tubes that fills the volume also grows with the volume, unlike the external surface that encloses that volume. When the volume is scaled, the tubes (i.e. capillaries) are not scaled in size, but they grow in number per a given fraction of the volume. So the scaled devices are not geometrically similar, thus the law of variation of the area per volume with scaling does not apply.
This is why a brain or a muscle can scale from a mite with a volume of one thousandth of cubic millimeter to a whale.
The scaling is not ideal because the smallest capillaries must be aggregated into vessels of increasing size, so some part of the volume becomes wasted, but still the ratio of area per volume does not decrease linearly, as in the case when the external surface is used for cooling.
The same technique is applied in many engineering domains. For instance, the maximum current for a power transistor depends on the perimeter of the source or emitter, not on the die area. Therefore, if one would scale a power transistor maintaining geometric similarity, the switched power per die area would drop quickly, leading to very high costs for the devices.
Instead of this, a bigger power transistor does not have bigger sources or emitters, but it has more of them, with the same size as in the smallest transistors, which keeps constant the power switched per die area.
Capillaries cannot defeat the divergence theorem: If you have a volume where heat is produced but the temperature does not increase, the heat has to leave via the surface. It is true that the surface area available to diffusion can scale at any rate (eg. Menger sponge), but the heat still has to leave the volume via its boundary. In the case of capillaries, this is by convection which means that the product of coolant temperature differential and flow speed has to scale.
Thanks, this is what I wanted to say, but perhaps I was a bit too terse.
Perhaps a good coolant with a good flow speed can gain you a decent constant factor versus a classical heat sink, but once the third dimension of your chip gets bigger, you will hit a barrier. Just do the math.
But it does, at least to some degree: For the cpu (or brain) you want high density to minimize the latency between components. For the heat sink, you want high surface area, which you can actually do to some degree three-dimensionally, particularly when you have active cooling. Look at a typical heat sink with a fan attached to it -- it has some depth, because that depth allows more heat to be transferred to the air to it by increasing the surface area exposed to the air. Lungs do the same thing, and they do function as part of our cooling system. So if you have a way that the flow of the exchange medium is not limited by the external surface area of your heat exchanger (a fan, a pump, a diaphragm), you can go pretty far.
It doesn't scale forever in the extra dimension but it does at least scale a hell of a lot better than just using the envelope of the volume or using a single flat layer.
There is no contradiction: simple amino acids as a basic building block being coopted by replicating RNA to build more sophisticated structures.
You can conceive other than nuclear-acids based replicant, using the same ubiquitous amino-acids to build a protein life not using RNA/DNA but some other encoding structure.
The question is what is the chemically most likely 'other'?
Also, what could be alternatives for ATP/sugars?
Sugars are just chains of hydrocarbons with alcohol groups, they are probably going to be ubiquitous. ATP is useful because the phosphate groups make a stable bond that nevertheless can be hydrolyzed, releasing a lot of energy.
But the adenosine "backbone" of the ATP is more-or-less arbitrary. Other forms of life can use something different. Or they might use the phosphorus bonds themselves where terrestrial life uses peptide bonds.
Disulfide bonds exhibit similar properties, and terrestrial life also uses them to give additional "rigity" to certain proteins. It's also likely a late addition to the genetic code, cysteine is nestled between two stop codons (it clearly used up the initially reserved block of the address space tagged for future expansion).
And if you look at meteorites, sulfur compounds are _much_ more common. Sulfur chemistry also doesn't require scarce fixed nitrogen that could only be replenished by lightning before nitrogen-fixing enzymes first evolved.
So I don't believe at all that exactly our RNA/amino acids are going to be universal.
I also do not believe that our RNA and complex amino acids are likely to be universal.
On the other hand, the simple amino acids are known to be universal, both from chemical analyses of celestial bodies and from abiotic syntheses in laboratories.
In theory, sugars can be produced abiotically by the polymerization of formaldehyde. However, sugars are not very stable chemically and suitable catalysts for formaldehyde polymerization seem to be rare, because sugars are much less ubiquitous than amino acids in lifeless environments.
The role of phosphorus in biology is determined entirely by the property of the phosphate anions that they can eliminate water and condense into polyphosphates, then the polyphosphates can extract water from other molecules, forcing condensation reactions, which can be used for various purposes, e.g. for building polymers.
The nucleoside parts of ATP and related substances play only the role of a "handle", which can be used to control the location of the polyphosphate parts, so that they will perform their function where intended.
Thus for controlling the polyphosphates other molecules may also be suitable.
Disulfide bonds, which already exist in the pyrite mineral, must have had a crucial role in the origin of life. But their role is very different from that of polyphosphates, because they extract hydrogen, instead of extracting water, so they perform redox reactions, not condensation/hydrolysis reactions.
Thioesters are the sulfur compounds that can play the same role as ATP, by taking part in condensation/hydrolysis reactions.
There is no doubt that all the 5 elements H, C, N, O and S, which happen to be the most abundant electronegative elements in the entire Universe, must be used by any living being, since the origin of life. Whether phosphorus has also been used since the beginning, or it is a later addition, is uncertain, because thioesters could have been used originally for performing all the functions now done with phosphates like ATP.
Both nitrogen and phosphorus are affected by similar availability problems. While nitrogen is too volatile and most of it would always have been stored in dinitrogen gas, which is inert, instead of being stored in easy to use ammonia or hydrogen cyanide molecules (while hydrogen cyanide and carbon monoxide are now toxic for most living beings, it is likely that they both are very important for the appearance of life), for phosphorus the problem is that most of it is stored in insoluble phosphate minerals. This must have been alleviated around the origin of life by the fact that the early oceans were much more acidic than today, so much more phosphate ions would have remained dissolved in sea water, than today.
Unlike for phosphorus, there is no substitute for nitrogen in biology. The role of nitrogen in organic molecules is the same as the role of dopants in semiconductor devices. When nitrogen substitutes carbon in an organic molecule, that position in the molecule becomes positively charged, instead of being electrically neutral. These electric charges play very important roles in many chemical reactions.
The poor availability of nitrogen must have been the main constraint in the growth of the early forms of life, until the development of the nitrogenase catalysts that allow the use of dinitrogen from the atmosphere.
Similarly, it is likely that the earliest forms of life used carbon from carbon monoxide, whose lower availability limited growth until the development of a catalyst that reduces carbon dioxide to formic acid, which allowed the use of the more abundant carbon dioxide. Both catalysts, which are used to capture carbon dioxide and dinitrogen, appear to have used in their earliest variants molybdenum, or possibly the related tungsten. While molybdenum seems to be a later addition to the set of chemical elements used for life, iron, cobalt and nickel are all necessary for the appearance of life as catalysts, while potassium is also necessary since the beginning for maintaining the electrical neutrality of a water solution without producing solid precipitates that would cause death.
The abilities to use directly carbon dioxide and dinitrogen, which are the main constituents of most planetary atmospheres, and which were also the main constituents of the early atmosphere of the Earth, must have greatly expanded the environments suitable for life, which previously must have been restricted to small neighborhoods of hydrothermal vents or sources of volcanic gases.
- cells appear very soon after the hadean Earth
- meteorites contain life building blocks
These suggest that the life chemistry evolved in the proto solar cloud (and exploring the conditions in there would yield how that happened) and the life on Earth evolved from the already complex stuff that fell on it after the hadean phase.
Theoretically yes, but honestly I doubt it. Simple hydrocarbons are too stable, water molecules disassociate naturally (that's what pH means!). Water is also polar and can dissolve significant quantities of polar compounds. Ethane is non-polar.
But crucially, the speed of chemical reactions goes down by 2-3 times for every 10C. Ethane liquefies at -160C so most chemical reactions would be around 100000 times slower than at 0C. And many chemical reactions would not work at all because of the high activation energy.
It's possible that low-temperature life might utilize some highly unstable (at room temperature) compounds. But there are few low-energy pathways that can be used to _synthesize_ these compounds in the first place in nature.
Around 38% of new cars sales in Finland in 2025 were EVs [1], so they apparently have figured out how to make them work. PHEVs were another 20%. Gas cars were around 39%, and diesel cars were about 4%.
EVs work in cold weather, just the range is reduced.
If it is a second car in the family, used for short range commuting ... or if your lifestyle does not involve frequent long-distance trips, EV is perfectly suitable even in Finland.
In those countries most people own a house so they can plug in every night.
Where I live it's all apartments (without parking because they were built before cars existed) and there's maybe one charging station on the street per 300 spaces or so. A few more in parking garages but you pay hundreds a month to access those.
I don't think an EV will work here until every space has a charger.
Sounds like you might live in a sensible place where you probably don’t need a car at all. That’s the ideal! Unfortunately, much of, e.g., the U.S. (outside of ~4 cities), “cities” are built around individual car ownership. There, where a car is pretty much necessary, and you likely already have a dedicated spot to store it, it often makes sense to choose an EV version.
Forcing Iran to obtain a nuclear weapon, load up on missiles and drones and then use them to attack Gulf neighbors, destabilize Lebanon, Syria, or Iraq, or fund terrorists as recognized by both the United States and European Union (Hamas, Hezbollah, Houthis).
Forcing North Korea to murder and starve its citizens and deprive them of medicine, food, and access to education and more. Nor is it forcing North Korea to go send Korean soldiers to die for Putin's war in Ukraine.
Speaking of - the US isn't forcing Russia to invade and murder Ukrainians.
The US didn't force Maduro to come to power and create a humanitarian crises in Venezuela resulting in 1/3rd of the population fleeing as refugees, nor did the US force their economy to be mismanaged for the enrichment of Maduro and his cronies.
The US isn't forcing China to threaten Taiwan.
There are plenty of other things. But without the US, China invades Taiwan, Ukraine falls (don't forget, it was the English and Americans who were flying in weapons and other equipment round-the-clock while Europe was having meetings to decide what to meet about), Iran obtains a nuclear weapon and seizes the Strait permanently or at least kicks off a nuclear arms race in the Gulf, and thugs like Maduro continue to kill and impoverish people throughout South America.
It is actually. Iran can see that their only viable path to stability is nuclear deterrence. This attack makes it more obvious.
>North Korea to murder and starve its citizens and deprive them of medicine, food, and access to education and more
No murder and starvation are US domestic policies.
>The US didn't force Maduro to come to power and create a humanitarian crises in Venezuela resulting in 1/3rd of the population fleeing as refugees, nor did the US force their economy to be mismanaged for the enrichment of Maduro and his cronies.
How far down into non sequitur are you at this point.
Unless your interceptor system is unobtainium laser system with unobtainium cooling system, backed-up by unobtainium power source, you are going to run out of interceptor missiles (or even Phalanx bullets) way sooner than 'million missile attempts'.
Quite possibly 100-200 Shaheds + half a dozen proper anti-ship missiles will cause you to turn tail.
there are so many options from coil guns, to lasers, to jammers, to non-nuclear EMP's, ... that don't involve the caricature of a million dollar missile intercepting it.
Would Russia/China/US not use their nukes if in risk of being overrun by conventional forces of another superpower?
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