You're confusing the importance of avoiding Kessler syndrome in LEO with the difficulty of causing Kessler syndrome. GEO debris can potentially remain there for millions of years before interactions between the gravitational pull of the Sun, Earth, and Moon sufficiently perturb it. LEO debris remains for weeks to months. You have to have many orders of magnitude more debris in LEO to trigger Kessler Syndrome, where the rate of collisions exceeds the rate of debris loss.

The fact that a LEO Kessler Syndrome would also be short is something that exists on top of that.

It's also worth nothing that not only are modern satellites not only vastly better at properly disposing of themselves than they were in the 1970s when Kessler Syndrome was proposed, but they're also vastly better at avoiding debris strikes. All of these factors are multiplicative together.

Immunology, presumably.

The only donor bodies that aren't going to treat the transplant as an act of war are clones or heavily immunosuppressed; and it's probably more plausible to assume that you'll be able to clone a human like a sheep than assume that you'll be making some fundamental breakthroughs in immunology to deal more elegantly with unmatched hosts.

I can see the utility of having spare organs in certain emergencies; but how much life extension would you actually get even if the sort of neurosurgery involved in removing a brain and reattaching it to a new host's spinal cord were viable? Is the theory that the assorted ghastly flavors of neurodegeneration are actually to be blamed on older organs and everything will be fine; or is this just a very expensive way to ensure that you skip the various ways peripheral organs can kill you and are assured to be the spryest patient in the dementia ward?

Lol, I was thinking of this instead ;)

People forget that the primary concerns about Kessler Syndrome were about geosynchronous orbit, which used to be where all the most important satellites went (many of course still go there, but not the megaconstellations). It takes a long, long time for debris to leave GEO. But LEO is a very different beast.

They said it's internal rather than a collision, so probably a failed COPV would be my guess.

Yeah. In particular:

with fragments likely to fall to Earth over the next few weeks

LEO FTW. Kessler Syndrome is primarily a risk if you put too much stuff with too poor of an end-of-life disposal rate in GEO. End-of-life without proper disposal rates have declined exponentially since Kessler Syndrome was first proposed (manufacturers both understand the importance more, and do a better job, of decreasing the rate of failures before deorbit - in the past, sometimes there wasn't even attempts to dispose of a craft at end-of-life). And now we're increasingly putting stuff in LEO, where debris falls out of orbit relatively quickly. It's not impossible in LEO, esp. with higher LEO orbits - but it's much more difficult.

Or to put it another way: fragments can't build up to hit other things if they're gone after just a couple weeks.

And this trend is likely to continue - a lower percentage of premature failures, and decreasing altitudes / reentry times. Concerning ever-decreasing altitudes, we've already been doing this via use of ion engines to provide more reboost (with mission lifespans designed for only several years before running out of propellant, instead of decades like the giant GEO ones), but there's an increasing interest in "sky skimming" satellites that function in a way somewhat reminiscent of a ramjet - instead of krypton or xenon as the propellant for an ion engine, the sparse atmospheric air itself is the propellant, so the craft can in effect fly indefinitely until it fails, wherein it quite rapidly enters the denser atmosphere and burns up.

ED: "But it doesn't work for gravity with linear curvature"

Relativity = gravity is represented by the curvature of spacetime. Curvature is linear, R. The formula treats curvature linearly. As things get closer and curvature spikes, the math just scales at a 1:1 rate

Quadratic gravity = Squares the curvature. Doesn't really change things much when everything is far apart, but heavily changes things when everything is close together.

Pros: prevents infinities and other problems when trying to reconcile quantum theory with relativity ("makes the theory renormalizable"). E.g. you don't want to calculate "if I add up the probabilities of all of these possible routes to some specific event, what are the odds that it happens?" -> "Infinity percent odds". That's... a problem. Renormalization is a trick for electromagnetism that prevents this by letting the infinities cancel out. But it doesn't work with linear curvature - gravitons carry energy, which creates gravity, which carries more energy... it explodes, and renormalization attempts just create new infinities. But it does work with quadratic curvature - it weakens high-energy interactions and allows for convergence.

Cons: Creates "ghosts" (particles with negative energies or negative probabilities, which create their own problems). There's various proposed solutions, but none that's really a "eureka!" moment. Generally along the lines of "they exist but are purely virtual and don't interact", "they exist but they're so massive that they decay before they can interact with the universe", "they don't exist, we're just using the math out of bounds and need a different representation of the same", "If we don't stop at R^2 but also add in R^3, R^4, ... on to infinity, then they go away". Etc.

The theory isn't new, BTW. The idea is from 1918 (just a few years after Einstein's theory of General Relativity was published), and the work that led to the "Pros" above is from 1977.

A bit more about the latter. Beyond organophosphates, the main other alternative is pyrethroids. These are highly toxic to aquatic life, and they're contact poisons to pollinators just landing on the surface (some anti-insect clothing is soaked in pyrethrin for its effect). Also, neonicotinoids are often applied as seed coatings (which are taken up and spread through the plant), which primarily just affect the plant itself. Alternatives are commonly foliar sprays. This means drift to non-target impacts as well, such as in your shelterbelts, private gardens, neighbors' homes, etc. You also have to use far higher total pesticide quantities with foliar sprays instead of systematics, which not only drift, but also wash off, etc. Neonicotinoids can impact floral visitors, with adverse sublethal impacts but e.g. large pyrethroid sprayings can cause massive immediate fatal knockdown events of whole populations of pollinators.

Regrettable substitution is a real thing. We need to factor it in better. And that applies to nanoplastics as well.

So, when we say microplastics, we really mainly mean nanoplastics - the stuff made from, say, drinking hot liquids from low-melting-point plastic containers. And yeah, they very much look like a problem. The strongest evidence is for cardiovascular disease. The 2024 NEJM study for example found that for patients with above-threshold levels of nanoplastics in cartoid artery plaque were 4,5x more likely to suffer from a heart attack. Neurologically, they cross the brain-blood barrier (and quite quickly). A 2023 study found that they cause alpha-synuclein to misfold and clump together, a halmark of Parkinsons and various kinds of dementia. broadly, they're associated with oxidative stress, neuroinflammation, protein aggregation, and neurotransmitter alterations. Oxidative stress is due to cells struggling to break down nanoplastics in them. They're also associated with immunotoxicity, inflammatory bowel disease, and reproductive dysfunction, including elevating inflammatory markers, impairing sperm quality, and modulating the tumor microenvironment. With respect to reproduction, they're also associated with epigenetic dysregulation, which can lead to heritable changes.

And here's one of the things that get me - and let me briefly switch to a different topic before looping back. All over, there's a rush to ban polycarbonate due to concerns over a degradation product (bisphenol-A), because it's (very weakly) estrogenic. But typical effective estrogenic activity from typical levels of bisphenol-A are orders of magnitude lower than that of phytoestrogens in food and supplements; bisphenol-A is just too rare to exert much impact. Phytoestrogens have way better PR than bisphenol-A, and people spend money buying products specifically to consume more of them. Some arguments against bisphenol-A focus on what type of estrogenic activity it can promote (more proliferative activity), but that falls apart given that different phytoestrogens span the whole gamut of types of activation. Earlier research arguing for an association with estrogen-linked cancer seems to have fallen apart in more recent studies. It does seem associated with PCOS, but it's hard to describe it as a causal association, because PCOS is associated with all sorts of things, including diet (which could change the exposure rate vs. non-PCOS populations) and significant hormonal changes (which could change the clearance rate of bisphenol-A vs. non-PCOS populations). In short, bisphenol-A from polycarbonate is not without concern, but the concern level seems like it should be much lower than with nanoplastics.

Why bring this up? Because polycarbonate is a low-nanoplastic-emitting material. It is a quite resilient, heat tolerant plastic, and thus - being much further from its glass transition temperature - is not particularly prone to shedding nanoplastics. By contrast, its replacements - polyethylene, polypropylene, polyethylene terephthate, etc - are highly associated with nanoplastic release, particularly with hot liquids. So by banning polycarbonate, we increase our exposure to nanoplastics, which are much better associated with actual harms. And unlike bisphenol-A, which is rapidly eliminated from the body, nanoplastics persist. You can't get rid of them. If some big harm is discovered with bisphenol-A that suddenly makes the risk picture seem much bigger than with nanoplastics, we can then just stop using it, and any further harm is gone. But we can't do that with nanoplastics.

People seriously need to think more about substitution risks when banning products. The EU in particular is bad about not considering it. Like, banning neonicotinoids and causing their replacement by organophosphates, etc isn't exactly some giant win. Whether it's a benefit to pollinators at all is very much up in the air, while it's almost certain that the substitution is more harmful for mammals such as ourselves (neonicotinoids have very low mammalian toxicity, unlike e.g. organophosphates, which are closely related to nerve agents).

There's legitimacy to that. Taking a potentially dangerous drug under the supervision of a doctor who knows how things are supposed to work, what side effects look like, with drugs of consistent purity and dosage, has a lot of advantages over winging it with stuff made up random chinese chemicals and toilet bowl cleaner.

Unless you're talking about cocaine etc. brought to the penthouse by a personal assistant or something. Plenty of ultra-rich celebs have killed themselves that way.

How can it be that? Survival has never been more assured. I wonder if we'd be less depressed if we had to do physical labor for food and fight the neighboring tribe once in a while to punctuate life with more immediacy and urgency.

Mostly just in the bulk, low barriers to entry, and pervasiveness(like a lot of things social media). The case of actors actually goes back a long way; state laws regarding compensation of child actors were spurred by the case of one who was popular in the 1920s and litigated with his parents over where the money wasn't in 1939. That case doesn't provide for takedowns; but it's also the case that filmmakers are normally looking for children to play characters; rather than to do 'candid' intense documentaries of them at home; so the degree of public exposure of private life is presumably deemed to be less; with the main issue being children who were...definitely...getting a solid education while on stage finding that all the money was gone when it became their problem.

Child-blogging, by contrast, seems to reward verisimilitude (if not necessarily truth) and invasiveness, relatively pervasive in-home mining for 'content', so presumably seems better served by removal-focused options; though there has definitely been talk about covering the economic angle in line with child actors.

I don't even know what the deal is with child beauty pageants, or how something you'd assume is a salacious bit of slander about what pedophile cabals are totally doing, somewhere, is actually a thing a slice of parents are into, way, way, into. Apparently that's a third rail to someone, though, as the only jurisdiction I'm aware of with significant restrictions on them is France.

Unless quantum computing becomes cheap and comparatively widely available quite quickly after becoming viable passwords seem like they'll be a manageable problem. Nobody likes rotating them; but it's merely tedious to do and the passwords themselves are of zero interest unless they are still being accepted. If it does go from 'not possible' to 'so cheap we can just go through through in bulk' overnight that could ruin some people's days; but if there's any interval of 'nope, the fancy physics machine in the dilution refrigerator is currently booked by someone with a nation state intelligence budget' you can just rotate older credentials.

Now, if you were hoping that encryption was going to save any secrets that are interesting in and of themselves that got out in encrypted form; then you have a problem. Those can't be readily changed and will just be waiting.