Trading a lower frequency of war for a more devastating consequence has worked thus far, but when people start to act like such consequences are an impossibility they’ll push risk right up to the edge - and someday someone will eventually go over it. Ironically triggering the thing that was supposed to be impossible.

Basically, we're screwed if the world doesn't trend towards peace. And even times of peace will always be liminal, because people are people. So I think we should (1) aiming for positive relations, (2) aiming to minimize the scope and scale of the wars that do inevitably happen, and (3) aim to get setup on other planets.

Perhaps the first planet to nuke/virus itself to death can work as a more visible reminder of the dangers for the others. We always learn best by putting our fingers in the fire (and it's no surprise that games of nuclear chicken are arising only once Hiroshima/Nagasaki fall out of living memory), but this is pretty darn close to it at least.

There is no multi-planetary scenario in which a nuclear war on Earth doesn’t also target the country’s off-world settlements.

Then you'd also need to know a lot like how nukes would even work on Mars. Dramatically lower atmospheric pressure, amongst other things, will mean nukes will function dramatically differently and be substantially less dangerous. You're looking at dramatically reduced shock/blast waves, less of a threat of fallout (since environmental exposure is already lethal), and so on.

It's another great argument for expansion - each colony will have to deal with different situations, which makes various threats - less threatening. For another example, a directed gamma ray burst could be catastrophic on Earth, and is one hypothesis for the Great Ordovician Extinction, but on Mars it would almost entirely harmless.

The capacity to gently land 150 tons on the surface of Mars, is also the capacity to make 150 tons land at, at least, Martian escape velocity — equivalent to an explosion of 411 tons of TNT.

Doesn't matter if it's RFGs instead of nukes, the people are just as dead. And any belligerents during a nuclear war on Earth will have grounds to presume second-strike capability exists on any affiliated off-planet colony, so will be motivated to attack those colonies as part of the nuclear war on Earth.

> For another example, a directed gamma ray burst could be catastrophic on Earth, and is one hypothesis for the Great Ordovician Extinction, but on Mars it would almost entirely harmless.

Are you sure? I thought even exceptionally focussed GRBs were about 0.1°, and that angle corresponds to maximal Earth-Mars separation at just 0.025 light years, at which point I'd be more worried about the gravitational pull of the GRB star removing both Earth and Mars from Sol orbit.

On Mars its effect would be largely inconsequential.

There are a few books on the subject: eg. https://books.google.com.au/books?id=6mGGX6AGBTAC

I'd venture the biggest threat of a GRB not dampened by distance would be the explosive event that caused a sun to release as much energy in a few seconds as our Sun will in its entire 10-billion-year lifetime.

No.

A GRB strong enough to reduce Earth's ozone layer by half, would be about 100 kJ/m^2:

https://ntrs.nasa.gov/api/citations/20050179464/downloads/20...

On Mars, where there's no ozone layer in the first place, and the atmosphere is much thinner, and there's no magnetosphere, IIRC just over half the radiation from a GRB reaches the ground.

Given a human cross-sectional area from above is about 0.25 m^2, that means that a human outside during such an event would get 25 kJ almost entirely absorbed by their body.

A lethal dose for a 100 kg human is about 1 kJ absorbed. And when I say "lethal", 1 kJ absorbed is 99%+ lethal within 2-14 days, even with immediate treatment, and the victim suffers rapid incapacitation due to CNS failure.

You'd need to bury everyone under, IIRC, 2-3 meters of regolith to protect against that. You'd also need your crops underground for the same reason. If you're going to all the trouble to have a farm functioning under several meters of soil, you can also do the same things needed for that, on Earth, far more cheaply.

Furthermore, the nitrogen dioxide levels expected in such an event, would reduce Earth surface sunlight levels by 10-60%. Mars, just by being further from the Sun, gets a reduction of 48-64% (varies over the Martian year) relative to Earth — even when there's no planet-spanning dust storms, which it also gets.

I gave you a citation, that is about GRBs and interaction with the atmosphere. That's where 100 kJ/m^2 comes from. First page, even, it's in the abstract.

Radiation absorbed dose is measured in Grays, which is Joules/kg, and 8-30 J/kg is the lethal range I gave you, easy to find with trivial search but also so well known you shouldn't need to be told about it if you're serious about rad hazards.

You get from J/kg to J by accounting for mass, and from kJ/m^2 to J by accounting for cross sectional area. Hence 25 kJ actual, and 1 kJ lethal limit.

You can look up radiation mean-free-path shielding constants if you want, but I'm not walking you through what is foundation-level knowledge in this domain. Me, I got that knowledge by having an interest in atomic rockets and fusors back at university, it's not hard to find.

If you can't apply the inverse square law to get Martian sunglight relative to Earth's, or if you don't know about its missing ozone layer or missing magnetosphere, you have no business even thinking about a Mars colony.

At this point, why expect an AI based answer to miss citations when they've got a big friendly button saying "search" right there in the web UI?

In a world with colonies, those colonies become nuclear targets. You may not even have to expend a juke—just ram a ship into it.

My point is that the same logistics that would sustain a Martian colony make striking it easier. Mars isn’t a solution to war on Earth. It’s a long-term insurance policy against planet-wrecking accidents, whether natural or human.

As for viruses, it’s like someone millennia ago arguing that humans expanding to more continents reduces the risk of disease. Yes, for a bit. But the same factors that enable that expansion make global pandemics possible.

It is much easier to build a long term viable bunker without rocketing the construction materials. If we are to take the extraordinarily optimistic goal of $100kg at face value the price of building anything substantial on Mars is prohibitive. To have a truly independent colony it would require a substantial number of factories.

Getting people on Mars will be inspiring and humanity's greatest achievement to date. That it also serves as a 'backup' for humanity, is something that provides a motivation get it done ASAP in times like those that we live in, but is in many ways also largely incidental.

So the idea of a backup is not that we just go live on Mars, but rather that we have a significant number of people on Mars (and elsewhere ideally) that can return to Earth in such a scenario, help restore order, find/rescue survivors, and generally get society going again. It's simply the planetary equivalent of being able to send in aid to an area after a catastrophic force majeure.

So does Earth.

The downsides of Mars:

• Colder than Antartica • Drier than Sahara • Lower air pressure than top of Mount Everest • Soil perchlorate concentrations on par with a Superfund cleanup site • Atmosphere contains negligible oxygen, nitrogen; you need the former, plants need the latter, you need the plants • No ozone layer (not that you're ever going to be outside, what with the air being unbreathable in two distinct ways) • No magnetosphere (so CMEs are dangerous rather than being pretty light shows) • We don't even know yet if the lower gravity is important

I say this as one of the people who finds Mars inspiring, and would even consider being a Martian colonist: The technical capacity to make Earth as uninhabitable as Mars already is, would also threaten Mars.

Nukes? Mars colonies are much more vulnerable. Engineered viruses? If they existed, private companies could already ship them to Mars — etc.

If your goal is a backup for repopulating after a disaster, we can already do hermetically sealed metal boxes isolated from the outside world for long durations at a time, where at least one such box of people is always secreted away in an unknown location at any given moment: nuclear submarines.

It's because Pakistan has nukes. Nukes essentially make wars unwinnable. This [1] describes the effect of a tiny 0.15Mt nuke going off in NYC. The largest nuke ever detonated was 50+Mt, so more than 300x the yield of what's described there.

And that's one nuke. Pakistan is believed to have hundreds of nukes, and nuclear weapons are also designed such that a single missile will have multiple warheads that will splinter off not only increasing the destruction but also making any sort of missile defense even less viable.

[1] - https://www.atomicarchive.com/science/scenarios/newyork/inde...

There is no world in which Pakistan could nuke America. I agree on the effect—nukes gave Islamabad cover it wouldn’t have had without them. But the mechanism isn’t military strategic, but something deeper.

Nukes are also the ultimate defensive weapon. Any forces, ships, etc deployed on or near their territory would be toast. One of the many reasons that naval forces are largely obsolete. Aircraft carriers are sitting ducks worth tens of billions of dollars. Pakistan's known nuclear capable missiles have a range of 2750km which means even long distance aerial bombardment is not an answer.

I’m less worried about WW3 starting in anger than I am about it starting by oopsie/craziness/terrorism.