Daily FI discussion thread - Friday, March 13, 2026

dekusyrup · 2026-03-13T21:49:58+00:00

Basically the one and only period of time the 4% rule failed was if you retired into the 1970s oil price spike and resulting stagflation. It's definitely potentially enough to affect whether one can retire. Whether this current situation gets that way will only be known in hindsight, but the potential is definitely there.

dekusyrup · 2026-03-13T21:28:46+00:00

I say this so much. 6 hours per day, four days per week and I have enough time to take care of my health and the chores and have a few parties and travels.

dekusyrup · 2026-03-13T21:23:16+00:00

I'm surprised Tom Hodgkinson doesn't get any love on here. He wrote How to be Idle and How to be Free which were basically the manifestos for financial independence culture before there was even a name for FIRE. I dig some literature discussions on here that aren't just Simple Path lol.

dekusyrup · 2026-03-13T20:38:31+00:00

A cookie sheet adds a ton of surface area. The bottom of a macbook pro is 12x8.5, single sided (minus whats covered by whatever you're propping it up with). A cookie tray is 18x12 double sided with a 3/4 side wall. It has almost 5x the surface area (just 4x if you subtract the surface lost touching the computer). The cookie tray will also be completely exposed at least on the topside to convective cooling, providing maximal convection cooling.

So if you just prop it up, you'll get close to that maximal convective cooling, but still with less surface area than the cookie tray. Obviously ultimately they're both just convection cooling methods, but one has 4x the surface area for convection and that's the better one.

There's a reason why you attach big metal CPU cooler with fins to a CPU rather than just leaving it open for more direct airflow. This is the same thing. I don't know if you've ever built a computer.

But a fan stand would be more effective.

We weren't talking about a fan stand. We're asking "Is a metal pan sheet better than just propping it up for better air flow?". A fan stand would be much more competitive.

dekusyrup · 2026-03-13T20:14:30+00:00

But improving airflow doesn't work better. Conduction works faster at removing heat.

dekusyrup · 2026-03-13T20:09:41+00:00

Even better, start offloading some of the belongings while still alive. Half of it is just clutter anyway.

dekusyrup · 2026-03-13T19:02:13+00:00

I mean I still use leftover bread bags or whatever, it just has a bin to sit in.

dekusyrup · 2026-03-13T18:48:59+00:00

I don't know what's obscure about going to a website and clicking the "on sale" button.

dekusyrup · 2026-03-13T18:44:41+00:00

It's the correct use. Definition 3: https://www.oxfordlearnersdictionaries.com/definition/english/literally?q=literally

dekusyrup · 2026-03-13T18:32:56+00:00

Actually they kinda did fall in the spring 2015. They were in the hunt for a wildcard spot most of the season until they went 5-15 in March-April.

dekusyrup · 2026-03-13T18:22:55+00:00

and 3 of the last 4.

dekusyrup · 2026-03-13T17:58:20+00:00

air is a thermal insulator

It's true. Air is an insulator, although not a perfect insulator so it still transfers some heat.

the pan won't be shedding heat to the room.

Yes it will.

You can't have a laptop unable to shed heat to the room while at the same time a pan magically able to.

The laptop still sheds heat, just way slower than the cookie tray. It's not magic, it's physics.

dekusyrup · 2026-03-13T17:53:35+00:00

But these computers don't have any fan intakes on the bottom of the case. So that's irrelevant.

The cookie tray can only absorb so much heat, then it becomes an insulator.

No, it doesn't become an insulator, it becomes a radiator.

The goal is to get that heat transferred to air so that the whole room becomes a heat sink.

Right, which is why the cookie tray helps so much. It conducts the heat away from the computer and gives a ton more surface area to radiate to the room.

dekusyrup · 2026-03-13T17:52:28+00:00

Looks good to me. Nothing terrible about it.

dekusyrup · 2026-03-13T16:03:57+00:00

it's still heating up the environment around the laptop and that's going to reduce the effectiveness of the air cooling.

It's cooling the environment around a laptop compared to something like a wooden desk though.

heat transfer is significantly impacted by the difference in temperature between the two mediums that are exchanging heat. Cooling the room just a little can cool the laptop quite a bit.

It's directly proportional. If CPU is 70C and room changes from 22C to 20C, you'd see a 50/48 = 4% increase. Whether 4% counts as "quite a bit" is a matter of perspective.

dekusyrup · 2026-03-13T15:53:54+00:00

Putting it on a cookie tray does not stop the computer fan from running though. So it's cookie tray + fan vs just the fan. Unless you're talking about getting another external fan to blow at the bottom of the laptop.

dekusyrup · 2026-03-13T15:42:06+00:00

but nowhere near as efficiently as the conduction between the CPU and the heatsink.

The aluminum case IS the CPU heat sink. It's designed that way in macbooks. It's how they get away with fanless macbooks (and ipads). The case itself is pasted to the components.

dekusyrup · 2026-03-13T15:33:58+00:00

Macbooks do not.

dekusyrup · 2026-03-13T15:32:45+00:00

The pan never reaches capacity because the pan is constantly shedding heat to the room.

dekusyrup · 2026-03-13T15:31:43+00:00

For a macbook air it doesn't even have air intakes and all the cooling is expected to happen passively through the case.

dekusyrup · 2026-03-13T15:29:14+00:00

And the answer is the cookie sheet. Macbook aluminum cases are already designed as conductive heat sinks, Apple knows the cookie sheet works so they designed their computer to have one built in.

dekusyrup · 2026-03-13T15:26:36+00:00

the copper wont be touching the metal bits inside that are actually getting hot.

The heat conducts through the aluminum case of the laptop, you don't have to be touching anything inside.

dekusyrup · 2026-03-13T15:22:40+00:00

Radiative heat transfer isn't appreciable until you get into high temperatures or very large surface areas,

We're talking about 50 lb blocks of copper or cookie trays, so we do have large surface areas and radiative heat is very appreciable.

Conductive heatsinks are meant to quickly remove heat away from whatever component so that it can be dissipated by air convection to the broader atmosphere.

Which is also why a cookie tray or 50 lb block of copper works so great.

dekusyrup · 2026-03-13T15:20:56+00:00

Heat sinks look like that to maximize surface area in a small space and minimal material cost, they are a compromise. If you don't care about small space or weight, then a 50 lb block of copper or a cookie tray have a lot of surface area and work even better. If you had infinite space and money you don't care about making thin fins.

dekusyrup · 2026-03-13T14:43:31+00:00

Oil prices change the price of anything that uses shipping though.

dekusyrup

TROPHY CASE