I'm 99% sure the hardening part was a joke

Thank you, sir.

I am still not sure if the joke was bad or if everyone takes everything too seriously nowadays.

I guess it was simply too close to reality. That's why I didn't register that as humor. Text also doesn't carry tone of voice well, which makes confusion more likely

Usually the rule is that the personal item must fit under the seat in front of you, the carry-on may be a bit larger.

I have boarded with a wheeled carry-on + wheeled personal item (a backpack with wheels) in the past, but every time the gate agent tested the personal item for size.

I'm sure that's technically true -- but as long as your personal item doesn't have wheels they seem completely unconcerned with the size. I frequently travel with a duffel bag carry-on that goes in the overhead. On most flights they let me waltz onto the plane with it and a backpack long after they start forcing everyone to gate check their rollerboards.

They could also just say "only one carry-on can go in the overhead bin."

The specific rule is that a personal item must be able to fit under the seat in front of you, in that space, without any sort of extension into the aisle.

At most gates, I've seen the little boxes that are used to size test carry on luggage to also have a section to size test personal items.

My experience is that it barely fits a large backpack with some books, snacks, and at least one 15 inch laptop.

Carry on luggage can be much, much larger.

> I frequently travel with a duffel bag carry-on that goes in the overhead

Yes, that is one carry on luggage item, and one personal item.

>They could also just say "only one carry-on can go in the overhead bin."

No because you are not afforded two carry on luggage items. One item has to be small enough to fit under the seat in front of you.

Depends, if you are turning that electricity into heat using a heat-pump you might win on most situations (maybe lose if the weather is really cold outside, unless you add geothermal loops, but then its a lot more expensive to make)

No it wouldn't depend. Electricity generation and electricity transfer has losses. Gas transfer has loss only if there is a leak.

Heat pumps have a COP value of around 4 to 5 (10 to 15C outdoor) and 3 (0C outdoor). The seasonal COP (or SCOP) measures the efficiency over a whole season, and that typically sits around 3 to 4. That means that for 1kWh of electricity a heat pump delivers 3 to 4kWh of heat to the house.

Burning gas to heat a home means "1kWh" of gas, delivers ~1kWh of heat.

Modern gas power plants are about 55 to 60% efficient, so "1kWh" of gas becomes ~0.57kWh of electricity, which after transport losses (-6%) arrives at the home as 0.52kWh, which gets turned into 1.5 to 2.0kWh of heat.

=> It's almost two times as efficient to turn gas into electricity and use heat pumps in the home

But a gas burning furnace can have 100% efficiency, that is trash compared to what I get from a heat pump considering a gas power-plant (60%) * national grid efficiency (90%) * heat-pump 500% efficiency where I am (combined efficiency around 270%, or 2.7 times the gas furnace).

The only gas-based solution to get close would be using a gas generator at home (30%) to power the 500% heat-pump, and routing the 70% of waste heat inside (to get a combined 220% efficiency).

But that heavily depends on the heat-pump efficiency, which will depend on your ambient heat and instalation.

The ceiling is not 100% efficient, when you have a heat pump.

Also, the US residential gas infrastructure leaks ~1% of the gas it moves. That sounds like nothing, until you account for how unburnt ch4 is ~80 times worse than co2 on a timescale of 20 years.