I suppose that's possibly handy, the problem is these "repairable" phones are usually specced pretty low, making them unattractive to enthusiasts who would actually be likely to do any repairs. Replacing the battery isn't something normally done within the 3-year or so life of a phone, anyway. I'd frankly be much more interested in a phone that's easy to install alternative software on.

So, a swappable battery is now considered "repairable"? We're rapidly devolving.

https://www.thejakartapost.com/life/2020/03/11/the-eternal-enigma-of-leonardo-da-vincis-mona-lisa.html

There's actually about 10 or 12, of differing levels of similarity. Some are very close, some not so much.

Everybody interested in this topic needs to read John Rechy's The Sexual Outlaw.

Tell it to the Hindenburg.

They don't exist in any meaningful quantity.

I suspect you're leaving the conversation because you can't prove me wrong. Here's what I suggest: go buy yourself a tank of hydrogen, hook it up to your car and get it to run, and then devise a method to refill this quickly and conveniently. Do this, and then come back here and continue the discussion about the practicality of hydrogen as a combustion fuel.

But before you go to all that trouble, let me give you just a little fyi. You see, unlike you, I've actually worked with this shit in the past doing plastic brushing. I've actually handled hydrogen. The stuff is violently explosive, extremely flammable and completely odorless and colorless. It also burns with no visible flame. Leaks are about impossible to detect. A standard size 300 steel compressed gas tank is about 5 ft tall and about 10 inches in diameter and weighs about 132 lb. At 300 bar (4500 PSI) this tank will hold maybe a kilogram of hydrogen. A kilogram of hydrogen is equal to about a gallon of gasoline in pure energy. So you can start to get some kind of idea just how much hydrogen you would actually need to drive your car even a short distance assuming you could devise a system to deliver it... Which I'm assuming wouldn't be too difficult because it would be similar to the natural gas delivery systems which are in fairly wide use in the trucking industry right now, and which have been around for decades. I actually had a van years ago with a dual-fuel CNG conversion. Total pain in the ass. Huge tank hanging underneath gave a range of maybe 120 miles. Only one place in town to fill it, 20 miles away. Took it all off and threw it away. So there you go. There's your Dunning-Kruger epic.

Let me tell you why this doesn't make sense, either economically or environmentally. Nearly all of these "green" ideas are just robbing Pete to pay Paul. Carbon-neutral is a pipe dream. Humans haven't been carbon-neutral since they learned how to use fire. Nearly all of human technological development has been based around one fact: that we live on a planet where there's enough oxygen to support combustion non-explosively, and where there's substantial amounts of heavy metals available on the surface. This has made it possible to develop literally every single technological artifact you take for granted, from the zipper in your pants, to the hinges in your eyeglasses, to the tiny screws that hold your iPhone together, to the massive turbine shafts in the generators that provide your power, to the shiny stainless steel Elon Musk uses on his yet-to-fly-anywhere Starship. And it all requires heat, most of which derives from combusting carbon and oxygen at some stage. This is reality, and ignoring it just ignores the point.

The reality is that there probably isn't enough lithium available to power a fully electrified planet in any realistic near-term scenario, we haven't hit that wall yet, but will soon. This will cause prices to spike and possibly upend a developing market. Hydrogen and fuel cells are even more un-leverageable. Cracking hydrogen either requires vast amounts of electricity, which we don't have available (and most of what is available creates carbon dioxide), or you can crack it from natural gas, which actually creates more carbon dioxide than simply burning the natural gas, and natural gas has a much better energy density to start with.

Fuel cells aren't an answer to any large-scale need, they're extremely expensive, require significant amounts of precious metals that are already in high demand for other industrial processes, and don't work well in cold weather, requiring additional outside energy sources to keep them heated. And here you seem to be suggesting the solution is to build a vast fleet of rockets to haul infrastructure to the asteroid belt looking for more platinum and iridium, when the fact is launching rockets is one of the most polluting and carbon-unfriendly things we do. One launch produces more pollution and carbon dioxide than a thousand jet flights or a million car trips. It's absurd. It reminds me of the articles I used to read in old Popular Science magazines, about how we could have nuclear-powered cars by the 1980's, as the technology was "perfectly feasible". They weren't wrong, the technology was perfectly feasible, just completely impractical. We've had miniature nuclear reactors for 60 years. But they were expensive then and they're more expensive now. And nobody wants a nuclear reactor in their garage. Mining asteroids isn't infeasible, just impractical. Hydrogen fusion isn't infeasible, just impractical. My shitty old Nissan isn't carbon-neutral, but it's way more carbon neutral than building a new EV, or cracking hydrogen which costs six times as much as gasoline, or launching rockets to the asteroid belt looking for platinum, which may or may not be there.

Now, if you'll excuse me, my car is warmed up and I'm going to be driving down to a non-carbon neutral restaurant to have a non-carbon neutral sandwich.

You have no clue how markets work. As soon as there's demand, the price will increase, not go down...in the same way the price of electricity is increasing even as more and more wind and solar comes online. "Make it at scale"...how? By cracking it from hydrocarbon? This is not only not green, it creates more carbon than just burning the natural gas. This is the only "at scale" method that currently exists. Increasing the scale doesn't decrease the refining cost, because the energy cost doesn't change. It takes around 33kwh per kilogram using electrolysis. A kilogram of hydrogen is like a gallon of gas. Hydrogen is currently around 5-6 times the cost of gasoline here in the US, without even beginning to delve into the difficulties of storing, transporting, and figuring out how to actually get it into a car. It's a red herring.

Hydrogen requires much more energy to extract from water than you get from it...which makes it inefficient by definition. There is no infrastructure to power huge cracking operations. The vast majority of hydrogen is currently extracted from methane, which emits more carbon than just burning the methane. Solar/wind infrastructure is going to be needed for the general use grid. Hydrogen requires massively thick tanks and huge compressors to compress it. It's extremely explosive and burns with no flame. It's far more dangerous to handle and store than liquid fuels like gas or diesel.

You're not totally wrong, but I bet most every technology you depend on in your day to day life was developed and marketed in the USA originally.

Only in your imagination. There's no infrastructure to support large electric vehicles, and no economic incentive to buy them. Like a lot of people, you see one article about some prototype somebody built, and you assume a million cash-strapped construction companies running on narrow margins are suddenly borrowing billions of dollars to buy fleets of vehicles that don't exist that have no support infrastructure.

And they dropped it as pointless, since there's no hydrogen infrastructure, and hydrogen is cracked from hydrocarbons. Hydrogen has poor energy density, it's way cheaper and more efficient to just burn the hydrocarbon.

The price will not drop. It will increase.

Where are these fuel cells? They don't exist.

Who's "projecting" this? I don't believe you can pack enough hydrogen into an airliner to equal the range available from jet fuel...not to mention the tanks would be massively heavy.

There isn't enough platinum and iridium in the world to make any significant number of fuel cells.

99% of hydrogen is cracked from hydrocarbons. Hydrogen is not green.

His tribe will be hunting you though.

When I was a kid I had nightmares that little people like this lived under my bed and inside the wall.

The nuclear engine concept was abandoned because the weight of the engine was massive, and because of the social and political implications of what would happen if there was a launch accident or a crash.

That's just weird. Dogs are usually triggered by the odor of reptiles and will instinctively try to bite it or run away.

Oxygen supports combustion. Most other gases don't. You can't combust hydrogen without oxygen, it's already the simplest element. Helium is an inert gas like nitrogen. For life to take place chemical reactions need to take place.

These things are not trivial to calculate at universe-spanning distances where relativistic effects and universe expansion become factors. Doing some simple math and ignoring these factors, at it's current velocity based on measured red shift, the Saraswati supercluster would be about 280,000 light years farther away in a million years, and 280 million light years in a billion years, although that later figure would be off by an increasingly large factor. The Andromeda galaxy is moving towards our galaxy at a much lower velocity, so in a million years it would be around 1000 light years closer, and in a billion years about a million light years closer.

FYI I am not a professional astronomer or cosmologist.