I got nerd-sniped on this, so let's do the math.

Volume of a AAA battery = ~3.85 cm^3

And let's give it a density of the densest elemental metal (Osmium), at 22.6 g/cm^3

Assume the battery stores pure energy (I know, I know). So E = mc^2, which is like 8.99 x 10^16 J / kg

So that battery would hold about 22.6 g/cm^3 * 3.85 cm^3 * 8.99e16 J / kg = 7.8 * 10^ 15 joules = ~2.2 TWh, about a trillion times more than a normal AAA battery.

Doing some LLM-assisted sleuthing, a large cruise ship can use over 80,000 gallons of fuel a day [1]. A bit of searching indicates marine fuels have a density of approx 39 MJ/L (I'm using volumetric density for consistency), so 80,000 gallons * 39 MJ/L = about 1.1 x 10^7 megajoules = 3.2 GWh.

So a 2.2 TWh AAA battery could power that ship for 671 days.

Of course, the practical physics here are nonsense and there are obvious safety considerations associated with your AAA-sized nuclear weapon, but maybe that's what the author was getting at?

[1] https://blog.windstarcruises.com/how-much-fuel-cruise-ship-u...

The last thing humanity needs is a way to store that much energy in the palm of your hand. It would take about five of these impossible batteries to match the energy released during the Tunguska event.

Exactly, I assume this is the kind of thing the author is thinking about. But going this far into the extremes of theoretical physics and calling it "hard, but possible" is somewhat misleading on their part. Commercial fusion power is "hard but possible", and even that's an understatement. Ship-mounted matter-antimatter power or whatever should not be implied to be within the same category.

A small to medium size cruise ship has an engine at around 24'000 HP ≈ 176 MW.

The smallest terminal you can connect to a AAA battery is the same diameter as 00 AWG copper wire.

Provided that the engine has 100% efficiency and can turn 176MW of electricity into torque, to safely run power it needs through that 00 AWG wire, the battery would need to provide a voltage of at least 70 kV.

If an AI has figured out how to turn all of the internal mass of a AAA battery into electrical energy, it's not too much of a stretch to think it's could have also found a room temperature super conducting alternative to copper.

How to protect yourself from spontaneous release of energy in case of cell failure? This problem gets worse with density

Energy density. This would be approximately 10^9 to 10^10 times the capacity of a real cell, would be better than fusion fuel, and almost 1% of the theoretical maximum.

It violates the laws of thermodynamics.

You don't even need to be an expert to poke at why this is extremely implausible.

Think about the materials involved. What material stores all this energy, which one assumes is inert and room-temp? And if it's not inert/room-temp, what material contains the other material?

In each case, how much mass is needed of each - to store, and to contain? Noting also that the more mass you need of the energy-bearing material, the more you will need of the other. Can that mass be compressed into 4 cubic centimeters?

I personally have no idea, but it's sure sounding impossible.

The article starts that section with “As the Big Bang has so loudly illustrated” so I assume the author is imagining a machine that replicates the conditions of the Big Bang. Exactly how that could be constructed and used safely is left as an exercise for an AI.

This is same thing someone in 1926 would say about your cell phone battery

No argument, but my point is that the author's confident pronouncement that we can keep scaling is ridiculous, and your otherwise valid point earns the author net zero credibility.