> just use hydrogen

At that point, why not package the hydrogen on a carbon chain...oh wait.

A lot of these schemes compare poorly against synthetic jet fuel manufactured from atmospheric carbon.

Likely the issue is cost. We can make liquid H2 pretty cheaply these days. We don't know if synfuel can get close to that price.

Or not bother with air taxis, civilisation won't collapse because some rich arsehole can't get across New York in five minutes.

It also won't collapse because some rich arsehole won't be able to post comments on Hackernews from their smartphone.

Sure, but on another hand we should encourage the rich asshole to spend his money so it could be useful to the rest of the economy.

But does it?

Just because it got a battery, it doesn't mean it actually solves the issue "getting around without taking forever and wasting resources" well. In the long run, it would be better to reduce commutes. And that's something we can do with some policies, on paper. No need to invent human slingshots or anything.

If climate casualties become serious, people might start questioning whether allowing people to be rich and be assholes and not contribute to solving the problem is sustainable...

Universal basic income and massive carbon taxes to pay for it!

It’s about time we tax actual destruction, not a minimum wage earner’s Netflix subscription.

Best way to do it I've ever seen is the automated transactions tax, whereby you replace most taxes with a small percentage taken on every financial transaction (plus a larger one when converting to/from cash to account for the black economy).

It's progressive because poor people will only pay twice (once on their salary/benefits, once when buying stuff), whereas rich people will pay several times when moving money around.

Expect a new class of companies to spring up overnight that are dedicated to bundling transactions to avoid this new tax. For instance, I could make a single transaction to my broker that covered all of my expected expenditures for the month, and that broker would then disburse it to my payees, bundling it with funds from other payers to avoid the tax on the other end.

I am strongly in favor of a tax on all stock market transactions, though—anything to deter HFT, which IMHO has little societal benefit while externalizing a ton of risk.

Wouldn't work. Tax law can tell the difference between an individual transaction and bundled transactions. It's also the only area of law that allows for ex post facto changes to the criminality of acts.

Tax law already handles much more complex schemes. Admittedly nowhere near perfectly, but then this scheme being simple frees up resources for policing, and the tax code being much simpler makes it less easy to exploit.

Why tax the income side when you could just tax the consumption side?

Taxing consumption is regressive; Bill Gates can't eat that many more hamburgers than the average person.

Write everyone a cheque.

Taxing income is quite regressive too: it’s how people with nothing can survive.

Taxing income at a few % as this scheme intends is not regressive.

For simplicity's sake. All transactions are taxed equally, no way to evade it by making false or borderline claims about the nature of exchange, and no resource have to be wasted on optimizing or litigating them.

Hydrogen is denser by weight, but by volume the story is completely different. The tanks need to be large.

What if most of the aircraft was hydrogen tank or bag? Then it could use the hydrogen for some of its lift! We can call it an "airship".

Or compress the hydrogen, but then you have 700 PSI handling issues and the tanks have to be very strong.

> We can call it an "airship".

Yeah, let's make a huge one and call it the Hindenburg! That sounds like a foolproof plan.

Too bad that there hasn't been decades of materials science improvements, including and in particular to handling flammable materials, between some highly propagandized disaster and today.~

(Almost every modern cruise ship is bigger than the Titanic, imagine if people acted like the Titanic was the last word on how big a cruise ship could get.)