If I take a step back and think back to say a few (or 5) years ago, what LLMs can do is amazing. One has to acknowledge that (or at least, I do). But as a scientist it's been rather interesting to probe the jagged edge and unreliability, including using deep research tools, on any topic I know well.
If I read through the reports and summaries it generates, it seems at first glance correct - the jargon is used correctly, and physical phenomena referred to mostly accurately. But very quickly I realize that, even with the deep research features and citations, it's making a bunch of incorrect inferences that likely arise from certain concepts (words, really) co-occurring in documents but are actually physically not causally linked or otherwise fundamentally connected. In addition to some strange leading sentences and arguments made, this often ends up creating entirely inappropriate topic headings/ sections connecting things that really shouldn't be together.
One small example of course, but this type of error (usually multiple errors) shows up in both Gemini and OpenAI models, and even with some very specific prompts and multiple turns. And keeps happening for topics in the fields I work in in the physical sciences and engineering. I'm not sure one could RL hard enough to correct this sort of thing (and it is not likely worth the time and money), but perhaps my imagination is limited.
I think those in the computer science field see passable results of LLM use with respect to software and papers and start assuming other engineering fields should be easy.
They fail to understand other engineering fields documentation and process are awful. Not that computer science is good because they are even less rigorous.
The difference is other fields don’t log every single change they make into source control and have millions of open source projects to pull from. There aren’t billions of books on engineering to pull from like with language. The information is siloed and those with the keys now know what it’s worth.
Not OP, but here is my observations:
The llm are uniformly dumb and not "understaging" across all spectrum of topics. It is counter-intuitive. By asking llm to simply blab ("write a story about ..") you notice it:
- mixes up pronouns (who is "you" or "he")
- cannot keep track of what is where.
- continuously plugs it's guidance slant ("lets cook dinner, Bob! It is paramount to strive for safety and cooperation while doing it!")
— language style is all over the place, comically so.
— when asked about the text it just generated, is able to give valid critique to itself (i.e. having that "insight" does not help the generation)
Journalists may have shallow understanding of topic, but they do not start referring to a person they write about as "me" halfway through.
This is the model conflating correlation with causation. Perhaps with more data spurious correlations would disappear, but the 'right' way is to make the models learn causal, world models.
Well, and I think the future of LLMs is not just in the pure LLM, but the agentic ones. LLMs with deterministic tools to ferret out specifics. We're only starting here but the results will be far better than what we do today.
Agentic LLM by itself provides value, to be sure, but they could also be part of learning a causal model. That's how humans do it; by interacting with the world.
Most the universities will do the thing asked in order to re-instate their student visa certification. i.e. provide intel needed to deport any students that they believe have opinions that are not in the interest of national security.
Most likely Harvard will try to fight it in court and then give in if they lose. It's not likely we see the future decertification continue into the academic year.
This is the country of free speech zones away from the main event in the early 2000s and sending WWI dissenters to jail in 1914. You’ve long pretended to have freedoms you’ve never actually been given and this is hardly new.
More like those freedoms get violated on occasion in the name of national security, because administrations are largely able to get away with it during certain crisis.
Great question, right to the heart of the matter. First higher learning, somewhere down the line, ordinary people? In my small world, I'm very clear I'm anti-trump on every issue. As an ordinary person, how long before I get on some Stalin type radar? If trump lobbies for and gets a third term, will there be an awakening to how far the abuse will go?
I expect some government AI will soon be trawling through the databases of every social media network and assembling a political profile of every US resident. (They’re already starting to do this for tourists and visitors: https://www.newscientist.com/article/2479045-us-government-i...)
Can they really do this? You're telling me this is real and not one of those "just for show" things that have no real teeth and will eventually get overturned by a judge?
I mean Harvard will fight back in court. The courts are last bastion. Once the executive branch stops following what the courts order the checks and balances are gone.
Lol Rubio told Xinis on national TV he was intentionally stonewalling any information to her, and she took it like a bitch and just kept rolling with keeping most their 'secrets' under seal (despite earlier talking big game of exposing them to sunlight).
The courts aren't even trying, they could order someone into contempt, but they won't.
We are in a non-constitutional crazy train territory, which will continue unless the right leaning voters do something about it at mid-terms. We're in the beginning of a very dangerous era.
They're not going to do anything about it. This is what they voted for. They thrive on our fear and anger. This is their revenge for the perceived wrongs of the Obama and Biden administrations.
By that logic, Trump's orders are just words. The Trump administration obeys the courts - they push the envelope way too far, but it is still rule of law.
That's one person. While it's very important, it doesn't at all mean the courts don't exit.
> order from the Supreme Court to return him.
The Supreme Court did not order that.
Edit: If you object to these things, realize you are helping the Trump administration by spreading exaggerated fears about what's happening. They want people to believe they are super-powerful, unstoppable, inevitable; it intimidates people into inaction. Also, without accurate information, people can't make good decisions and act - you are helping a propaganda campaign (unwittingly). And finally, spreading fear is not what good, responsible leaders - or teammates - do.
We have multiple judges beginning contempt proceedings against the administration, so this is open to debate.
And, there's recent action in the budget bill to attempt to defang judges' contempt powers, seemingly in response.
"No court of the United States may use appropriated funds to enforce a contempt citation for failure to comply with an injunction or temporary restraining order if no security was given when the injunction or order was issued"
That is happening, but it's a narrow instance. It doesn't mean there aren't serious issues, but the GGP said, "Checks and balances are just words." Obviously that is not true.
Also, Trump is relying on Congress to pass bills, for example. It's not rule by decree.
Will the people who had to transfer or leave be made whole? Even if a judge overturns this it will take time that the students impacted by this will have to pay, regardless of outcome.
Absolutely they have explicit powers to do this. Harvard is refusing to comply with the requirements of the visa program that allows them to bring student into the country so the administration is removing Harvard from the program.
There is little to no chance of this getting overturned.
Seems most universities don't really care as long as the money keeps flowing. They jumped quickly on the DEI bandwagon and they will quickly hop off too.
Between NIH grant-making being slowed down and this, there is no way to interpret these moves than being an underhanded way of causing university research infrastructure to collapse. Consider also, for example, that one Friday last month there was an announcement that indirect rates being cut to 15% for Dept. of Energy grants.. but only for universities, not companies or national labs!
Just from a steady state picture there is now significantly less funding flowing to America's research institutions and institutes. At some point buildings will be shut down, infrastructure mothballed and a generation of scientists will simply not be trained.
I don't think this is necessarily the right way to go about it, but there are deep issues with the incentives in the current US research system. As someone embedded in it, I would say it's highly dysfunctional and inefficient. Too much scientific fraud (hard and soft) and too many sinecures.
The answer to this problem lies here: “Entsminger pointed out that roughly 80% of the river’s flow is used for agriculture, and most of that for thirsty crops like alfalfa, which is mainly grown for cattle, both in the U.S. and overseas.”
The simple solution would be to raise prices on water such that it disincentivizes growing water hungry crops than alfalfa for example. The west’s water crisis is less about cities than agricultural choices made during the last century, which was wetter than it will be going forward. The obvious answer is to either regulate or incentivize using less water hungry crops more strongly. It would be better if this had started slowly a while ago, allowing the market to adjust and reallocate. Alas, looks like it will have to be an abrupt shift in the near future.
This community seems like its at its best when it expresses humble curiosity and its worst when it shuts the door on learning by oversimplifying deeply complex matters as though nobody else had the sense to look straight at them.
Water rights carry a legacy of centuries of personal and political history and thousands of competing interests. The levers with which to control price and set incentives the way you suggest don’t exist.
There are real problems looming, but there are no “simple solutions” or “obvious answers” being missed.
Whatever comes will involve great compromise and very few will think it was the right solution. I guess maybe you’re just joining that chorus early.
We can start by rolling back the modern entrenchments that have only made it worse. I would be absolutely shocked if this were only a 200 year old problem and there wasn't modern legislation basically gifting free water to special interests.
I'm by no means an expert or a lawyer or someone you should listen to. But this may hint at the complexity. A lot of water rights come from Spanish land grants ~330 years ago. And those were guaranteed by treaty after the Mexican American war. So, the U.S. can do whatever it wants, but treaties are in this weird space below the constitution but above a simple bill through congress to become law.
Water rights are generally old, old law and weird and complicated and special for each little town.
Mexican water rights were considered separate from the underlying land rights unless they were explicitly included in the grant. Moreover, Mexican title was required to be registered with the government shortly after annexation. Most of those titles were in turn siezed by various quasi-legal means, which is where cities like Berkeley come from. There are relatively few water rights remaining from Mexican annexation, most of which are held by municipal institutions like LA and only affect relatively small streams. Those of larger areas, like the Sangre de Cristo grant, have been litigated to death in courts over the past couple centuries and most of the entities involved no longer exist.
Water law is a nightmarishly confusing hellscape, but Guadalupe -Hidalgo isn't an important reason why today.
> things haven't reached that level, it's likely the issue isn't super serious (yet)
This isn't some some weird theoretical aside. Congressional power to modify and break treaties was debated by the founders [1].
Treaties are laws, full stop. Congress breaking them has political consequences. But it's not illegal, and it's no different from amending an act a prior Congress passed.
> if it got really really bad 3/4ths of the states can modify the Constitution and over-ride just about anything
You're describing extreme actions relative to a quotidien one. Armed revolution and Constitutional amendments are rare. Congress amending treaties is mundane.
We try to give the other side the courtesy of consultation, but that's (a) far from even common at this point and (b) sometimes impossible. The water rights in question are no different from any other private water rights. The fact that they originated from a treaty a curiosity at best.
What is so complex about eminent domain? Just force the sale of water rights back to the government for a fair price. It will sting a little bit, but sting far less than pretending like only 15% of the water in the western US actually exists.
Politicians are afraid of getting voted out, and frankly many of their constituents prefer to ban this or that symbolic thing in residential usage that scratches their control freak itch.
This is what I would expect to happen. Everyone wants the government to "simply" violate property rights and seize it but is there not a way for the market to sort itself out fairly? Are they forbidden from selling their water rights? Or is the water actually worth more to the farmers than the city residents so that the current situation is actually fine?
> Everyone wants the government to "simply" violate property rights...
It's a lot simpler when you don't believe that water is something private individuals have a right to hoard. Imo, water is a natural resource we all have some minimum access to as humans, regardless of if someone wants to buy it up and sell at a higher price later
It's not really natural though, is it? Regulated by the Hoover dam and supplying people living in deserts. Obviosuly people who choose to live in remote arid places don't automatically have the right to be provided with water by everybody else.
Obviously I'm talking about the transport of the water from where it naturally occurs to where people want to use it, not somehow creating it out of atoms.
Unfortunately the government sold it. Now of course they could buy it back ... That's unacceptable, apparently. Just taking it away, no compensation is what everyone seems to want.
And the price the current water holders want is apparently infinite because they claim the right to all the water that falls in perpetuity. We have removed rights to certain classes of objects before when managing other resources. If I recall correctly land deeds used to assume rights from heaven to hell but then air and mineral rights were carved off for the sake of commerce. We can do so again
This happens in some places already but a major issue is the absence of a distribution network to get water from where it is to where it is needed most. Being able to move the water consumption to where the water is located is one of the major drivers of cattle ranching out west.
I know you’re being earnest and understand the conviction behind what you’re saying, but I can’t help imagining that some of these comments are “false flag” posts by the NRA.
Completely overhauling property rights for half of a continent doesn’t come without major resistance. We’re still recovering from the last that that was done.
It’s just not as simple a problem as we’d all like it to be, and it’s not because this senator is in that rancher’s pocket.
Changing the law ignores the problem. This involves vast amounts of titled property with centuries of history. People respond very poorly to wholesale deprivation of property rights such that the political ramifications cannot be ignored, and the US Constitution puts strict limits on the nature of such deprivations.
This is essentially in the same class of situation as the government deciding to nationalize everyone's private home to solve some Important Problem. There isn't a realistic version of the world where that is a politically viable solution and the costs would be intractably high.
Changing the laws is not something that just happens and solves everything. If we're fixing legal doctrines from westward expansion of the US there is a lot to fix. I'd propose taking back the patchworks of land gifted to the railroads, or at least forcibly consolidate them into contiguous blocks.
Maybe those water rights should be given to the tribes who used to live in the watersheds. Let them set the prices.
Should someone be able to dig a well in their own land? Draw surface water from a river, stream, or creek that passes through it? Grow crops in their own flood plains, estuaries, marshes, ponds, and lakes?
The water we’re talking about doesn’t come through a pipe with a meter, and the people who have access to water have practical influence over the use, routing, safety, and quality of that water even if you try to assert legal control over them.
You and what 1,200 ft deep well? The aquifers are so depleted the land is sinking. It's just gone, and the rain isn't replenishing it fast enough. The water we're talking about is already more deep and less frequent.
Much of the water being discussed is in rivers and streams, which is taken as it passes through the land that uses it. It is only useful if it is in that exact waterway. There is no such thing as a market rate for water in a dry river.
If you turn it into an open market there are all sorts of weird complications. E.g. ranch A is upstream of Ranch B. Under a market system ranch A can use all of the water in the stream and just pay for it. Ranch B now doesn’t get that option since there is no more water in the stream. Rancher B can buy more water, but what good is buying water in a river that doesn’t go through your land.
So then you get to a rights based system. Rancher B has been watering his fields for 100 years, and rancher A comes along and says he wants to water his fields too. That’s fine, he just has to lay claim to whatever rancher B isn’t using.
The rights system would work fine except that nature won’t cooperate. We divided up rights for 100 units of water fair and square, so what do we do when we discover that we can only get 90 units of water.
Do you all take a 10% cut? Does the newest guy take the full cut (how it works now)?
You say it’s not complex, but millions of lives and industries worth trillions all rely on it. The current solution is a known flawed treaty that is almost 100 years old based on legal concepts that are far older. If it was so simple it would have been solved back then.
Lots of problems look like they'd be solved with heavy-handed authoritarianism, but there are costs to that both for individuals getting screwed over and the long term trust in the government to honor its agreements, reducing its strength in making future agreements. Plenty of 3rd world governments have happily seized property rights all over the place and it's not really a recipe for success.
Why not go a step further and just "solve" water shortages around the world by "forcing" some neighboring country that has too much water to sell it to you at the same price as to themselves? They weren't using it anyway, so that's fair, right?
Alfalfa is one of the most water efficient and nutritionally rich crops there is. It is also one of the most drought resistant crops. It is hearty and reliable, unlike corn which is far more wasteful when it comes to water.
> Deep-Rootedness—alfalfa roots are commonly 3-5 feet deep and can extend to 8-15 feet in some soils. Therefore this crop can utilize moisture residing deep in the profile when surface waters become scarce. It shares this property with crops such as orchards, vineyards, and sugarbeets and safflower, unlike crops such as onion, lettuce and corn, where it's easy to lose water past the root zone.
> Alfalfa's deep roots are capable of extracting water from deep in the soil, thus much of the water applied is not wasted. Additionally, deep roots enable the crop to survive periodic droughts.
> Perenniality—The fact that the crop grows for 4-8 years, grows quickly with warm conditions in the spring is a major advantage of alfalfa—it can utilize residual winter rainfall before irrigation is necessary. This is unlike summer-grown annual crops that need to be replanted each year (water use efficacy is low during this time). In many areas, the first cutting of alfalfa of the year requires zero irrigation– supported only by rain and residual soil moisture.
> Very High Yields—Alfalfa is a very high yielding crop, and can grow 365 days a year in warm regions (such as the Imperial Valley of California and southern Arizona). Its biomass yields are very high—we can get up to 12 cuttings per year in those regions, and growers with top management can obtain more than 14 tons/acre dry matter yields. High-yields create higher water use efficiencies.
> High Harvest Index, High Water Use Efficiency—Alfalfa's Water Use Efficiency is not only due to high yields, but because nearly 100% of the above-ground plant material is harvested (known as the harvest index). In most seed-producing and fruiting crops, only a portion of the plant is harvested (typically 30-50% of the total plant biomass).
Yes, market prices on water and beef (incorporating what are now climate externalities) would seem to solve these problems. Why isn't that being considered? Remember when conservatives, neo-liberals, and libertarians supported the market as a solution for everything?
Of course, we would need a reasonable amount of water available to consumers at below-market rates.
To me charging market price for water seemed obvious and easy till the comments here pointed out what should be obvious: the farmers Steve getting their water from the faucet but from their own wells, creeks etc. So that solution is pretty hard to do on practice.
Other than disgruntled voters, I don't see an obstacle for proper beef prices. In fact I wish we could price in carbon emissions, as I wish that pretty much for every price. I personally hope we'll soon see the day where you have to pay extra at McDonald's to get a beef patty instead of cyber meat.
I think as manufacturing and agriculture have become less labor intensive, a bigger proportion of the cost of things has been energy. So in a way, carbon emissions sort of are being priced into things naturally, and I'd guess the trend is increasing. In some extreme technological utopia, energy would be the only cost of food and products, meaning it's all carbon.
> I think as manufacturing and agriculture have become less labor intensive, a bigger proportion of the cost of things has been energy. So in a way, carbon emissions sort of are being priced into things naturally
But our carbon emissions are not priced into the cost of energy. That's the primary cause of the climate crisis!
> To me charging market price for water seemed obvious and easy till the comments here pointed out what should be obvious: the farmers Steve getting their water from the faucet but from their own wells, creeks etc. So that solution is pretty hard to do on practice.
It doesn't seem that hard to measure it. The large scale would justify the cost.
Some US beef is already produced with private water traded on the free market, at least in the western US. This is already priced into the cost of that beef. The price of water fluctuates every year but as a percentage of cost for beef, it isn't that much.
In places where water is scarce, like the US mountain west, all water is owned by someone. Drilling a well or having surface water does not entitle you to the water ipso facto, the water right has to be legally acquired from either a private owner or the State.
Prime grazing lands do not always come with water rights. Lease or purchase of that land to raise cattle requires acquiring sufficient water rights elsewhere. Since the State often has no additional water grants to allocate for that aquifer or water system, you then have to lease those water rights on the private market from an existing owner. While you could purchase titled water rights, they are rarely for sale since there is a ready market for renting them.
The reason this doesn’t happen is that farmers/farming lobbies have a lot of political power, especially in rural districts and no politician wants to be painted as anti-farming interests.
Unlike cities, farmers go where the water is. I know some HNers think farmers are growing crops in deserts. But that's just laughable. They farm where there is water: rivers, lakes, flood planes, deltas, etc. It is the cities diverting the water from these places.
> They farm where there is water: rivers, lakes, flood planes, deltas, etc. It is the cities diverting the water from these places.
What do you call a place where the lakes, rivers, flood planes, and deltas are dried up? That's right. A desert. If current trends continue that's exactly what you're going to have.
This was unfortunately the norm in his community at the turn of the century. A rather detailed study about the historical context of marriage among women in Ramanujam's community (Tamil Brahmins) is here: http://eprints.lse.ac.uk/46203/1/__lse.ac.uk_storage_LIBRARY...
From what I understand, it was common across many communities throughout India (though in Tamil Nadu, primarily among the Brahmins) for girls to be married before the onset of puberty (with consummation of the marriage only permitted post-menarche.. at least in theory). I do recall seeing a paper once that argued that the age of marriage actually became younger for some complicated reasons under British rule in the early 19th century.. not sure if that's believable.
As you might guess, I'm from the same community, and my great-grandmother was married at the age of 9 or 10. While one could attempt to rationalize and contextualize it, I think that's pointless: it was wrong then, as it is now.
Not analogous. Sons are practically obligated by family (and indirectly by the immediate society) to marry even against their will for keeping the tradition. Also females were considered unfit to get married after a certain (very young) age creating a pressure on girl's family to find a groom as early as possible. People created pseudo scientific and religious basis for enforcing these.
It was a social evil has rightly been banned but slavery was both a social evil and individual maliciousness on part of people who partook in it - and there were a few black folk too in that group who were selling their own people. No society 'mandated' slaverer to sell people as a way of life. There were always other professions if it didn't fit well with their conscience. No one would make your life hell for not actively selling slaves by making you into a social outcast.
I think the points raised are reasonable and, to my mind, not particularly partisan (though I would argue one party is more responsible for the current chaos by several orders of magnitude than the other one..).
The deeper issue this raises is, I suppose, a constitutional one paired with Long Now Foundation-type questions. How do we design institutions that can't themselves be changed too easily due to majoritarian whims, yet can evolve over decades and centuries as societies change. We certainly shouldn't expect the institutions and norms of today to precisely meet the needs of our descendants decades or centuries from now.
For the here and now though, my observation is this: Americans in general are allergic to learning from what other countries do. But really, as a very large country, we should be studying what smaller countries do and using them as experimental points of data and testing them out here. There are plenty of implementations of better, more responsive governance out there. Nothing's perfect, but saying 'we're number one' and plugging our ears is no solution.
Hi there - I'm the lead author of this paper. Not a big fan of this particular write-up.. it's not a solar panel at all! But happy to answer questions.
Semi-off topic but you should knowledge-able in the area, but would there be any potential in leveraging the permanent temperature differences which occur 10meters below the ocean? Light does not penetrate below 10meters and old water is denser. Thus the ocean, away from land, has a permanent and substantial potential energy difference between these two layers. Is it viable to harvest this difference?
Yes. It's called an OTEC (Ocean thermal energy converter) and it's a very old idea.
They are quite workable. In the simplest form, you have a 2 vacuum chambers at the surface, and a pipe to the bottom of the ocean. You vacuum out your pressure vessel down to around 3psi and let some warm surface water in one end, while pumping cold bottom water into a radiator in the other. At 3psi, the surface water flashes to steam in vessel A, drives a turbine into vessel B, and then condenses back into liquid water on the radiator. This brings the system pressure back down to where you started.
In practice, you'd probably use the surface water to warm a working fluid that is a gas at surface temperature and pressure, and then the system can stay at atmospheric pressure.
The benefit of this system is that it also creates an artificial upwelling of nutrients from the bottom of the ocean, which can be used to grow all sorts of stuff. Was a big hippy fad idea back in the 70's.
Is there a theoretical limit to the device's performance? Something relatable to power like milliwatts/m^2? How does this theoretical limit relate to the devices you've actually built?
Is it possible for a device to be both a solar panel and a radiative thermoelectric generator? How close to a theoretical limit for radiative thermoelectric generation could a device that was also a solar panel become?
Would capturing heat via mass e.g. warming up a block of cement during the day help improve the efficiency of a radiative thermoelectric generator that sits atop the heat source?
Is there a better term for this other than radiative thermoelectric generation?
There was an analysis done on the theoretical (Carnot/ 2nd Law) limits of using Earth's infrared emissions in this way: https://www.pnas.org/content/111/11/3927.abstract (Roughly 4 W/m2 for a system that purely exploited the radiative mismatch between outgoing and incoming long-wavelength radiation from the sky.
The bigger limit in our case is that we're using a thermoelectric generator - and achieving a relatively small temperature difference. We argued in the paper it might be possible with improved engineering and more favorable weather conditions to push performance to 0.5 W/m2.
In general, solar gets you far more power than this method ever will. The only advantage to combining the two might be to provide incremental power at night that improves the overall energy economics of the footprint associated with the solar panel.
And yes, a heat source would improve the power output. This has been the approach of an entire field of research that one might term 'waste heat recovery'. This encompasses everything from industrial sources to the human body or a campfire. The advantage, such as it is, of what we've done is that you don't need a source of heat besides the air itself.
> Is there a theoretical limit to the device's performance?
Yes.
Let the night-time equilibrium temperature be T_C (temperature_cold). Let the heat reservoir temperature be T_H (temperature_hot). The maximum theoretical efficiency is equal to 1 - T_C / T_H. This is from Carnot’s theorem and the 2nd law of thermodynamics.
The wasted energy is radiated off into space. You can calculate this with the Stefan–Boltzmann law. At 10°C we get 4.6 mW/m^2. (Edit: Whoops, bad arithmetic. Ignore these numbers. Do the math yourself.)
If your heat reservoir is 25°C and your cold temperature is 10°C then you have an efficiency of 5.0%. So you would generate 0.24 mW/m^2 at maximum theoretical efficiency.
You can even solve here for the optimum night-time temperature. Too cold and not enough heat is radiated. Too hot and the efficiency suffers. There is a maximum in the middle (but I am not going to do the math).
There are other interesting calculations I’m sure you can do to figure out maximum and minimum reservoir temperatures, but the challenge here is that you don’t want to harness sunlight to heat up your reservoir—you want to use existing heat that you have lying around.
Apparently, with our atmosphere we can achieve something like 40°C cooling in ideal conditions, and it is claimed that 60°C is possible. Back-of-the-envelope math suggests that you would achieve maximum theoretical power at around ~60°C difference.
With a reservoir temperature of 25°C my estimate is around 40W maximum power (with the correct arithmetic). You can get more power with a hotter reservoir.
Is the radiative cooler really just an aluminum disc painted black? Why this material versus some of the other designs out there (some groups have made these out of wood, others with glass microspheres in polypropylene, etc)
Yes! Most natural materials have a relatively high emissivity at the infrared wavelengths associated with "typical" room / terrestrial temperatures. So in that sense, pretty much any material you might have (except for a highly polished metal that might have low emissivity) is suitable to get some cooling using the radiative cooling effect at night.
The fancier materials work is for two things: 1) selective emission which can allow the radiative cooler to get to a colder temperature than a natural material (many/most of which have relatively uniform emissivity), and 2) high solar reflectance at the same time, which can allow radiative cooling during the day as well.
The OP prompted me to check on Shanhui Fan's group[1], which had done some sub-ambient radiative cooling in sunlight[2], and I stumbled on this recent work:
A dual-mode textile for human body radiative heating and cooling[3]
Unless you go out in the sun. But yes, if you're hot indoors, wearing black clothing can help by radiating more heat. (And white clothing can help in the sun by reflecting more incoming radiation.)
On behalf of all us, thanks for your work. Does the distance between the two surfaces at different temperatures matter? I'm sure this has occurred to you and your team, but the ambient temperature inside of a bedroom, beneath the roof, could provide a greater temperature differential.
Yes that distance matters in so far as getting the heat to the thermoelectric can be a bit more challenging. However I believe this has been investigated before and there are likely ways of doing it at least somewhat well.
Heat doesn't "really" get trapped by greenhouse gases.
The earth is constantly heated by the sun's light (light hits the air, heats the air; it hits the ground, it heats the ground) and it's constantly radiating heat away (the ground emits infrared and cools down). The hotter something is, the faster it emits heat, so based on the amount of incoming heat, the irradiated body hits a temperature where income=outgoing. More greenhouse gases just change the radiation/heat profile of the planet so that the point where income=outgoing ends up at a higher temperature.
You could actively cool the planet in principle, of course; but to do anything noticeable, you'd have to operate on geographical scales. You'd probably be better off building towers to the edge of the atmosphere and putting infrared radiators like this on top of those; otherwise, the your best bet would be to replace a few million square kilometres of a hot region with black paint and make sure there are never any clouds overhead.
> otherwise, the your best bet would be to replace a few million square kilometres of a hot region with black paint and make sure there are never any clouds overhead.
That would be counterproductive since black would absorb more of the sun's energy during the day than it would radiate at night. What you'd need is a way to have a black surface during the night and white during the day. (But barring that, white all the time is better than nothing, because it reflects more of the incoming sunlight. This is why melting of polar ice caps can accelerate climate change.)
One way to understand this cooling effect is that it occurs because at wavelengths where greenhouse gases are not substantially absorptive, heat can effectively escape out (or at least get absorbed and sent back to you at a higher altitude). The actual mechanisms are more complex than I'm describing as the atmosphere's temperature and composition varies with altitude, but the net effect from the perspective of a surface facing the sky is that, if you're at the same temperature as the air around you, you will radiate more heat out than the sky sends back to you.
All that being said, this is not in and of itself a climate change solution in the way you might be imagining. Most surfaces on Earth are effective at radiating heat already, and do so (it's in climate models). The difference here is we're thinking about actively making use of the cooling effect from a device, or building-scale to offset energy uses.
Huh. So this is why cars parked on one side of a street (with no tree cover) will be covered in condensation, while those parked on the other side (which has tree cover) will not?
I don't think it will reduce the need for energy storage. If it does, it might be in some marginal cases and by a small amount. This is because the power generated using this approach is quite a bit less than what you can get from solar. So for any conventional uses, PV+storage will always be the winner. I think the real advantage for this might be for low-power, long-duration applications where battery cycles can be a challenge. The other big scenario is polar climates, where there's low solar insolation for several months.
> I think the real advantage for this might be for low-power, long-duration applications where battery cycles can be a challenge
Correct me if I'm wrong but I guess it wouldn't make much sense to use something like that on a LEO small satellite right? But sounds pretty cool and handy to have such a setup on something larger like a lunar base right?
Following the Tolkien reference, migrants trying to cross the border are like Sauron’s army? Orcs? I’m not sure this world needs more ways of dehumanizing the desperate people and refugees seeking better lives.
Anduril aka "flame of the west" is Aragorn's sword. He uses it to fight orcs, but also to fight "Southrons" and "Easterlings", men under the influence of Sauron. (Make of that what you will)
Notably, Aragorn is able to defeat the latter two groups using his sword at the Battle of Minas Tirith, thus repelling them from "The West". I suppose Luckey thinks of his system as a way to repel evil people like the Southrons?
This is more likely Thiel's idea (Luckey's backer on both Anduril and Oculus) than it is Luckey's.
Thiel's companies Palantir Technologies, Valar Ventures, Mithril Capital, Lembas LLC, Rivendell LLC, and Arda Capital are all named after Lord of the Rings.
I was a huge fan of LotR as a kid. Then I started to notice Tolkien's attitudes about race, class, and sex seeping into it, and it lost a lot of its appeal. If Thiel's into it, that's the final nail in the coffin. This quote from John Rogers seems apropos.
“There are two novels that can change a bookish fourteen-year old’s life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs."
Of course there should immigration regulations, but because that's the comment you chose to make at this moment in this context, people are probably assuming that you believe the talking points about there being some big huge problem with illegal immigration in America, that somehow necessitates things like building a giant border wall and enabling ICE, etc. That would be eminently downvote-worthy, but of course you didn't say any of that. It's sort of like someone making a "both sides" comment after Charlottesville, it's hard to make a comment like that without it sounding like a dog whistle for some really bad people.
Illegal immigration is a big problem that directly affects citizens, unlike the foreign interventionism in the Middle East. Do you really think 12.5+ million illegal immigrants isn't a big deal? The system isn't adequate if that many can get in.
I am downvoting this because of the descendants of the illegal ANGLO immigrants who came to Texas in the early 19th century profit and cheer the criminalization of those doing the same thing.
No it’s not. America was not at war with Mexico during 1812-1836. Tens of thousands of gringos came and illegally squatted on land as well as raped and killed numerous Tejano families for their land. You should brush up on your history.
The United States of America had open immigration for the first 100 years or so. Not open citizenship, mind you, but open immigration. It wasn't until after the Civil War that SCOTUS forced the federal government to implement an immigration policy. Until then, this was the land of the free, and the home of the brave.
While no one should ever be dehumanized they should be reported accurately. Criminals (one who has broken the law) Illegal immigrate, Economic migrant.
I'm not sure how this issue plays out in the US but in Europe most of the media refuse to acknowledge this fact when reporting stories like this.
If I read through the reports and summaries it generates, it seems at first glance correct - the jargon is used correctly, and physical phenomena referred to mostly accurately. But very quickly I realize that, even with the deep research features and citations, it's making a bunch of incorrect inferences that likely arise from certain concepts (words, really) co-occurring in documents but are actually physically not causally linked or otherwise fundamentally connected. In addition to some strange leading sentences and arguments made, this often ends up creating entirely inappropriate topic headings/ sections connecting things that really shouldn't be together.
One small example of course, but this type of error (usually multiple errors) shows up in both Gemini and OpenAI models, and even with some very specific prompts and multiple turns. And keeps happening for topics in the fields I work in in the physical sciences and engineering. I'm not sure one could RL hard enough to correct this sort of thing (and it is not likely worth the time and money), but perhaps my imagination is limited.
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