Category: Science

New discoveries, the scientific method, and all matters relating to the scientific study of the physical world

The solar system’s other water worlds

I have mentioned Europa and Enceladus, moons of Jupiter and Saturn, as being among the most intriguing bodies in the solar system, since their liquid oceans create the potential that life could exist or survive there. Now we know that the dwarf planet Ceres, the largest object in the asteroid belt between Mars and Jupiter, also has an extensive reservoir of brine beneath the surface.

Any would be a fascinating target for scientific exporation, though with the crucial caveat that it would require better planetary protection techniques to prevent them from being colonized by organisms from Earth which might take over in any habitable niche and which could even exterminate extraterrestrial life. We now believe that despite efforts to sterilize them spacecraft on the moon and Mars likely harbour viable life forms from Earth. That may not pose much of a risk in a hostile environs with a thin or absent atmosphere and merciless radiation, but it must be among the central concerns for any mission which will visit a body with liquid water.

Advances in medication for HIV prevention and AIDS treatment

Truvada, a brand name for a cocktail of emtricitabine and tenofovir, is a daily oral prophylactic medication which has been found to be highly effective at preventing the uninfected from catching HIV. Now, a new drug is being tested which could provide the same protection in a way that’s more convenient and would be easier for people to use:

Cabotegravir is an integrase inhibitor—meaning that it works by stopping hiv copying its genome into the chromosomes of its host cells, an important stage in its life cycle. Unlike Truvada, which must be taken daily, by mouth, prophylactic cabotegravir is delivered as an injection once every two months.

In combination with the antiretroviral (ARV) drug rilpivirine, cabotegravir may also allow those who are already infected with HIV to be treated with periodic infections rather than multiple daily pills.

Open thread: steel without coal

The most pressing challenge for bringing climate change under control is replacing the world’s energy sources for electricity production, building heating and cooling, and transport. At the same time, humanity needs to learn how to do everything necessary to maintain a technological civilization without fossil fuels. That includes agriculture, as well as the production of crucial raw materials including steel.

This may be one area where hydrogen is a real solution:

[O]ne of the biggest industrial sources of carbon dioxide is not directly energy-related at all.

This is the reduction of iron ore (usually an oxide of iron) to the metal itself by reacting the ore with carbon monoxide made from coke. That produces iron and carbon dioxide. React the ore with hydrogen instead, and the waste product is water. Several firms—including ArcelorMittal, a multinational steelmaker, and a conglomerate of SSAB, a Finnish-Swedish steelmaker, LKAB, a Swedish iron-ore producer, and Vattenfall, an energy company, also Swedish—are examining this possibility.

Climate-safe sources of raw materials are necessary both practically and politically, since people point to the use of fossil fuels in their production as reasons why they cannot be abandoned.

Discrimination by artificial intelligence

I have seen numerous accounts of how — when an artificial intelligence or machine learning system is given a human resource task in the hope it won’t perpetuate human biases — biases in the material used to train the AI lead to it replicating the discrimination. As The Economist recently noted, this can happen even when information on things like the sex and race of applicants isn’t directly provided, since it can be inferred from other features in the data:

Such deficiencies are, at least in theory, straightforward to fix (IBM offered a more representative dataset for anyone to use). Other sources of bias can be trickier to remove. In 2017 Amazon abandoned a recruitment project designed to hunt through CVs to identify suitable candidates when the system was found to be favouring male applicants. The post mortem revealed a circular, self-reinforcing problem. The system had been trained on the CVs of previous successful applicants to the firm. But since the tech workforce is already mostly male, a system trained on historical data will latch onto maleness as a strong predictor of suitability.

Humans can try to forbid such inferences, says Fabrice Ciais, who runs PWC’s machine-learning team in Britain (and Amazon tried to do exactly that). In many cases they are required to: in most rich countries employers cannot hire on the basis of factors such as sex, age or race. But algorithms can outsmart their human masters by using proxy variables to reconstruct the forbidden information, says Mr Ciais. Everything from hobbies to previous jobs to area codes in telephone numbers could contain hints that an applicant is likely to be female, or young, or from an ethnic minority.

In part this is a subset of the black box problem in AI. For example, an AI intended to distinguish dogs from wolves learned to work out which photos had snow in them instead. Since the output from AIs is a set of tuned probabilities, it’s not possible to say what chain of reasoning or source of evidence led them to a conclusion; at the same time, this creates a risk that they will behave in unpredictable and unwanted ways.

Planting trees won’t solve climate change

Back in 2009, I described various ways to try to deliberately engineer the Earth system to reduce the severity of climate change and noted:

The first way to do this is to encourage the growth of biomass. This is relatively easy, but has limited potential. Biomass is like a giant carbon cushion: it can be thick or thin, but it cannot keep growing forever. Increasing the amount of biomass on Earth could draw down the amount of CO2 in the atmosphere a bit, but only if we also manage to cut our greenhouse gas emissions to practically zero.

Now that Prime Minister Trudeau has pledged to plant 2 billion trees as a climate solution (using expected pipeline revenue, to try to justify Canada’s continuing fossil fuel expansion) it’s worth having a post specifically on the limited ability of tree-planting to combat the problem.

A recent Slate article notes:

The notion that any significant percent of the carbon humanity spews can be sucked up by planted trees is a pipe dream. But it got rocket boosters in July, when Zurich’s Crowther Lab published a paper, in Science, proclaiming that planting a trillion trees could store “25 percent of the current atmospheric carbon pool.” That assertion is ridiculous, because planting a trillion trees, one-third of all trees currently on earth, is impossible. Even a start would require the destruction of grasslands (prairies, rangelands, and savannas) that reflect rather than absorb solar heat and that, with current climate conditions, are better carbon sinks than natural forests, let alone plantations. Also, unlike trees, grasslands store most of their carbon underground, so it’s not released when they burn.

The Crowther paper horrified climate scientists and ecologists, 46 of whom wrote a rebuttal, explaining that planting trees in the wrong places would exacerbate global warming, create fire hazards, and devastate wildlife. They rebuked the authors for “suggesting grasslands and savannas as potential sites for restoration using trees” and for overestimating by a factor of 5 “potential for new trees to capture carbon.”

Counter-intuitively, growing trees in order to burn them could actually be more of a climate solution, provided we develop the carbon capture and storage technology and infrastructure needed to bury the resulting CO2.

The coronavirus pandemic

I’ve avoided posting about the SARD-CoV-2 virus and COVID-19 outbreak, largely because anything I say is redundant when the news is largely comprised of saturation coverage.

Two stories did stand out today though:

I saw this yesterday: Coronavirus could push half a billion people into poverty, Oxfam warns

Still, despite all the claims that this will be transformational and alter life forever, I am skeptical. We tend to engage in hyperbolic discounting, assuming that what’s happening right now is the most important thing in history. At the same time, we have a tendency toward historical myopia, forgetting things soon after they are over or even losing interest before they have ended. I’m not saying there won’t be echoes and cultural callbacks to the pandemic — especially if we do end up physically distancing from one another for another six months or more — but I do suspect that we’ll ultimately weave the memories of this pandemic into what we take to be normal, along with mad cow disease, SARS, AIDS, H1N1, Ebola, and all the other biological risks which have troubled us and altered our lives in recent decades.

For my part, I have been in social isolation since mid-March: probably the longest I have ever gone without intentionally meeting someone.

Robots in agriculture

The Economist recently printed an article describing experimentation in the use of robots for agriculture, which included some interesting claims about potential environmental benefits:

The company will offer its robots as a service. Tom will live in a kennel on the farm, where it will download data for the farmer and recharge. Dick and Harry will be delivered to farms as and when they are needed, much as farmers already bring in contractors. This business model, reckons Mr Scott-Robinson, will demonstrate to farmers that the cost of using agribots will be competitive with other weed-control measures and provide additional benefits, such as being chemical-free.

…

When chemicals are required on crops, both tractor-towed systems and agribots could apply microdoses to the individual plants that require them, rather than spraying an entire field. Some trials have suggested microdosing could reduce the amount of herbicide being sprayed on a crop by 90% or more. basf, a German chemical giant, is working with Bosch, a German engineering firm, on a spraying system that identifies plants and then applies herbicides in just such a targeted way.

That’s certainly attractive compared to indiscriminate spraying of whole fields, though there will surely be downsides to such automation as well. Few people work in agriculture in rich societies already, but such technologies could affect the relationship between capital and labour nonetheless, and much more so in places where farming is less automated already.

Government and law enforcement back doors

One computer security concern is that various insiders — including hardware and software manufacturers, and governments which may compel them to comply — will build back doors into their products to allow the security to be compromised.

Doing this is a terrible idea. A back door put in for government surveillance or police use is also vulnerable to use for any purpose by anyone who discovers it. There’s no way to create strong encryption and security against everyone except the government, so building in back doors means deliberately spreading insecure systems throughout your society. When you deliberately design your systems to be vulnerable to one attacker (however well-motivated and regulated) you inevitably create an attack vector for an unauthorized person. You also face vulnerability if the mechanism of the backdoor is reverse engineered by unregulated agents, like criminal groups or foreign governments. With the degree of espionage focused in high-tech industry, it’s hard to imagine that any government could keep their back door strictly for their own use when well-resourced and determined opponents would also achieve many objectives through access.

The latest high-profile example of such a back door is the revelation that Swiss cryptography firm Crypto AG was secretly owned by the CIA. There have been numerous recent news stories, but the same information was reported in 1995. The National Security Archive has some further context.

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